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Imaging of the Lungs and Pleura

Pulmonary, or chest, imaging includes imaging of the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy and surrounding structures in the thorax. Imaging of the chest represents a substantial portion of the imaging tests that are routinely performed. Common imaging methods include X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests, CT, MRI, and ultrasonography (US). Each imaging method has advantages and disadvantages. Radiology exams, once completed, are read and interpreted by board-certified, fellowship-trained radiologists; however, most physicians Physicians Individuals licensed to practice medicine. Clinician–Patient Relationship should know the basics of how to interpret these images.

Last updated: Mar 14, 2022

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Introduction

Before interpreting any image, the physician should take certain preparatory steps. The same systematic approach should be followed every time.

  • Confirm name, date, and time on all images.
  • Obtain records of patient’s medical history and physical examination.
  • Confirm appropriate exam and technique for desired pathology.
  • Compare any available images of the same area obtained with the same method.
  • Determine orientation Orientation Awareness of oneself in relation to time, place and person. Psychiatric Assessment of image:
    • Right or left marker on X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests
    • In the United States, standard exam views place a marker (dot) to patient’s right.
    • For CT/MRI: On axial Axial Computed Tomography (CT) view, the image is sliced and viewed from inferior to superior (as if looking from the patient’s feet up).

Chest X-ray

Indication

Medical indications:

  • Emergency care:
    • Shortness of breath Shortness of breath Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
    • Chest pain Chest Pain Chest pain is one of the most common and challenging complaints that may present in an inpatient and outpatient setting. The differential diagnosis of chest pain is large and includes cardiac, gastrointestinal, pulmonary, musculoskeletal, and psychiatric etiologies. Chest Pain
    • Chest trauma
  • Routine care:
    • Signs and symptoms of pulmonary infection
    • Hemoptysis Hemoptysis Hemoptysis is defined as the expectoration of blood originating in the lower respiratory tract. Hemoptysis is a consequence of another disease process and can be classified as either life threatening or non-life threatening. Hemoptysis can result in significant morbidity and mortality due to both drowning (reduced gas exchange as the lungs fill with blood) and hemorrhagic shock. Hemoptysis 
    • Suspected mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast
    • History of ingested/inhaled foreign object
  • Monitoring:
    • Progression of pulmonary disease Pulmonary disease Diseases involving the respiratory system. Blastomyces/Blastomycosis
    • Tuberculosis Tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis screening Screening Preoperative Care

Nonmedical indications:

  • Verification of correct placement of IVs, lines, and tubes 
  • Postoperative

Advantages:

  • Low cost 
  • Low radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma dose 
  • Ubiquitous availability
  • Fast

Disadvantages:

  • Poor resolution of soft tissue Soft Tissue Soft Tissue Abscess
  • Exposure Exposure ABCDE Assessment to ionizing radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma
  • Patient must hold still for image.

Exam technique

Positioning:

  • Rotation Rotation Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. X-rays:
    • There should be no rotation Rotation Motion of an object in which either one or more points on a line are fixed. It is also the motion of a particle about a fixed point. X-rays.
    • Spinous processes midway between medial ends of clavicles
  • Visualization:
    • Lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy should be fully visible from apexes, above clavicles, to bases Bases Usually a hydroxide of lithium, sodium, potassium, rubidium or cesium, but also the carbonates of these metals, ammonia, and the amines. Acid-Base Balance.
    • Performed during inspiration Inspiration Ventilation: Mechanics of Breathing: 7–10 posterior ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy visualized above diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy
    • No superimposition of chin Chin The anatomical frontal portion of the mandible, also known as the mentum, that contains the line of fusion of the two separate halves of the mandible (symphysis menti). This line of fusion divides inferiorly to enclose a triangular area called the mental protuberance. On each side, inferior to the second premolar tooth, is the mental foramen for the passage of blood vessels and a nerve. Melasma over neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess or arms over peripheral chest

Positioning for specific views:

  • Posteroanterior (PA):
    • Board is against anterior chest.
    • X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests beams posterior to anterior direction through patient
  • Anteroposterior (AP):
    • Board is against back.
    • X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests beams anterior to posterior direction through patient
  • Lateral (from side):
    • Patient is upright.
    • Board is against left or right (L or R) side.
  • Lateral decubitus (from side laying down): 
    • Patient is supine.
    • Board is against side.
    • Patient is usually left side down on table.

Penetration Penetration X-rays:

Penetration Penetration X-rays is the degree to which radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma has passed through body, resulting in a darker or lighter image.

  • Good penetration Penetration X-rays:
    • Ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy are only faintly visible behind the heart. 
    • Vascular markings are clear but not prominent. 
  • Underpenetration: Film appears whiter and features are less apparent.
  • Overpenetration: Film appears darker and features are less apparent.

Interpretation and evaluation

Systematic approach:

  • Inside-out approach (central to peripheral):
    • Heart → mediastinum Mediastinum The mediastinum is the thoracic area between the 2 pleural cavities. The mediastinum contains vital structures of the circulatory, respiratory, digestive, and nervous systems including the heart and esophagus, and major thoracic vessels. Mediastinum and Great Vessels: Anatomy and hilum Hilum Lungs: Anatomy lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy/lung borders → chest wall Chest wall The chest wall consists of skin, fat, muscles, bones, and cartilage. The bony structure of the chest wall is composed of the ribs, sternum, and thoracic vertebrae. The chest wall serves as armor for the vital intrathoracic organs and provides the stability necessary for the movement of the shoulders and arms. Chest Wall: Anatomy → abdomen
    • Once an abnormality is noted, use the pattern approach to come up with differential diagnoses.
  • ABCDEFGHI approach:

Different views are used to evaluate different portions of the chest:

  • AP and PA:
    • Lung fields
    • Mediastinum Mediastinum The mediastinum is the thoracic area between the 2 pleural cavities. The mediastinum contains vital structures of the circulatory, respiratory, digestive, and nervous systems including the heart and esophagus, and major thoracic vessels. Mediastinum and Great Vessels: Anatomy 
    • Blood vessels
    • Pleural cavity Pleural cavity Paired but separate cavity within the thoracic cavity. It consists of the space between the parietal and visceral pleura and normally contains a capillary layer of serous fluid that lubricates the pleural surfaces. Pleura: Anatomy
  • Lateral:
    • Retrosternal space
    • Retrocardiac space 
  • Lateral decubitus: layering of fluid/air (e.g., pneumothoraxes, pleural effusions)

Normal findings

AP/PA view:

  • Heart and mediastinum Mediastinum The mediastinum is the thoracic area between the 2 pleural cavities. The mediastinum contains vital structures of the circulatory, respiratory, digestive, and nervous systems including the heart and esophagus, and major thoracic vessels. Mediastinum and Great Vessels: Anatomy:
    • Trachea Trachea The trachea is a tubular structure that forms part of the lower respiratory tract. The trachea is continuous superiorly with the larynx and inferiorly becomes the bronchial tree within the lungs. The trachea consists of a support frame of semicircular, or C-shaped, rings made out of hyaline cartilage and reinforced by collagenous connective tissue. Trachea: Anatomy midline
    • Shadow of superior vena cava Superior vena cava The venous trunk which returns blood from the head, neck, upper extremities and chest. Mediastinum and Great Vessels: Anatomy (SVC) immediately to right of mediastinum Mediastinum The mediastinum is the thoracic area between the 2 pleural cavities. The mediastinum contains vital structures of the circulatory, respiratory, digestive, and nervous systems including the heart and esophagus, and major thoracic vessels. Mediastinum and Great Vessels: Anatomy
    • Right and left hila
    • Right (right atrium) and left (left ventricle) heart borders are clearly visible.
    • Portions of ascending and descending aorta Descending aorta Mediastinum and Great Vessels: Anatomy are visible.
  • Lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy
    • Right and left upper lobes should be visible and clear.
    • Right and left lower lobes should be visible and clear.
    • Note: Right middle lobe is not well visualized from the PA or AP views, as it overlaps portions of upper and lower lobes.
    • Costophrenic and cardiophrenic angle should be sharp and visible.
    • Carina should be midline and faintly visible.
  • Bones:
    • Clavicles are visible and intact.
    • Scapula
    • Spinous processes midline, aligned with trachea Trachea The trachea is a tubular structure that forms part of the lower respiratory tract. The trachea is continuous superiorly with the larynx and inferiorly becomes the bronchial tree within the lungs. The trachea consists of a support frame of semicircular, or C-shaped, rings made out of hyaline cartilage and reinforced by collagenous connective tissue. Trachea: Anatomy
  • Organs:
    • Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy visible under right hemidiaphragm should be uniform with no free air.
    • Stomach Stomach The stomach is a muscular sac in the upper left portion of the abdomen that plays a critical role in digestion. The stomach develops from the foregut and connects the esophagus with the duodenum. Structurally, the stomach is C-shaped and forms a greater and lesser curvature and is divided grossly into regions: the cardia, fundus, body, and pylorus. Stomach: Anatomy and colon Colon The large intestines constitute the last portion of the digestive system. The large intestine consists of the cecum, appendix, colon (with ascending, transverse, descending, and sigmoid segments), rectum, and anal canal. The primary function of the colon is to remove water and compact the stool prior to expulsion from the body via the rectum and anal canal. Colon, Cecum, and Appendix: Anatomy visible with air in lumen under left hemidiaphragm. 

Lateral view:

  • Heart and mediastinum Mediastinum The mediastinum is the thoracic area between the 2 pleural cavities. The mediastinum contains vital structures of the circulatory, respiratory, digestive, and nervous systems including the heart and esophagus, and major thoracic vessels. Mediastinum and Great Vessels: Anatomy:
  • Lung:
    • Viewed from the right, all 3 lobes of right lung should be visible, and from the left, only 2.
    • Posterior costophrenic angle should be sharp.
  • Bones: Thoracic spine Spine The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy has regular Regular Insulin curve.

Pathologic findings

  • A: airway Airway ABCDE Assessment/airspace
    • Airway Airway ABCDE Assessment:
      • Deviated trachea Trachea The trachea is a tubular structure that forms part of the lower respiratory tract. The trachea is continuous superiorly with the larynx and inferiorly becomes the bronchial tree within the lungs. The trachea consists of a support frame of semicircular, or C-shaped, rings made out of hyaline cartilage and reinforced by collagenous connective tissue. Trachea: Anatomy
      • Asymmetric or evidently deformed bronchial tree Bronchial tree The collective term “bronchial tree” refers to the bronchi and all of their subsequent branches. The bronchi are the airways of the lower respiratory tract. At the level of the 3rd or 4th thoracic vertebra, the trachea bifurcates into the left and right main bronchi. Both of these bronchi continue to divide into secondary or lobar bronchi that bifurcate further and further. Bronchial Tree: Anatomy
    • Airspace:
      • Areas of increased density ( mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast, atelectasis Atelectasis Atelectasis is the partial or complete collapse of a part of the lung. Atelectasis is almost always a secondary phenomenon from conditions causing bronchial obstruction, external compression, surfactant deficiency, or scarring. Atelectasis, infection, foreign object, etc ETC The electron transport chain (ETC) sends electrons through a series of proteins, which generate an electrochemical proton gradient that produces energy in the form of adenosine triphosphate (ATP). Electron Transport Chain (ETC).)
      • Areas of decreased density ( pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax, hemothorax Hemothorax A hemothorax is a collection of blood in the pleural cavity. Hemothorax most commonly occurs due to damage to the intercostal arteries or from a lung laceration following chest trauma. Hemothorax can also occur as a complication of disease, or hemothorax may be spontaneous or iatrogenic. Hemothorax)
  • B: bones and soft tissue Soft Tissue Soft Tissue Abscess
    • Bones:
      • Fractures
      • Dislocation of ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy, clavicles, or shoulders
      • Spinal abnormalities
  • C: cardiac Cardiac Total Anomalous Pulmonary Venous Return (TAPVR) 
    • Enlarged heart (normal-sized heart is roughly ½ the width of chest), suggesting cardiac failure Cardiac failure Congestive heart failure refers to the inability of the heart to supply the body with normal cardiac output to meet metabolic needs. Echocardiography can confirm the diagnosis and give information about the ejection fraction. Congestive Heart Failure
    • Blurring of cardiac Cardiac Total Anomalous Pulmonary Venous Return (TAPVR) silhouette suggests something ( mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast, infection, fluid) in front of it.
    • Oddly shaped heart suggests congenital Congenital Chorioretinitis abnormalities:
      • Boot-shaped: tetralogy of Fallot Tetralogy of Fallot Tetralogy of Fallot is the most common cyanotic congenital heart disease. The disease is the confluence of 4 pathologic cardiac features: overriding aorta, ventricular septal defect, right ventricular outflow obstruction, and right ventricular hypertrophy. Tetralogy of Fallot
      • Snowman-shaped: total anomalous pulmonary venous return
      • Globular heart: pericardial effusion Pericardial effusion Fluid accumulation within the pericardium. Serous effusions are associated with pericardial diseases. Hemopericardium is associated with trauma. Lipid-containing effusion (chylopericardium) results from leakage of thoracic duct. Severe cases can lead to cardiac tamponade. Pericardial Effusion and Cardiac Tamponade
  • D: diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy
    • Asymmetric:
    • Incomplete:
      • Diaphragmatic hernia Hernia Protrusion of tissue, structure, or part of an organ through the bone, muscular tissue, or the membrane by which it is normally contained. Hernia may involve tissues such as the abdominal wall or the respiratory diaphragm. Hernias may be internal, external, congenital, or acquired. Abdominal Hernias
  • E: effusions (pleural)
    • White area at base of lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy
    • White area pushing against parenchyma on sides of lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy
  • F: fields, fissures, and foreign objects
    • Distortion Distortion Defense Mechanisms of normal anatomy landmarks may suggest mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast.
    • Radiopaque Radiopaque An object of high density that blocks X-rays (looks white) X-rays foreign bodies
    • Radiolucent Radiolucent An object of low density that is permeable to X-rays (looks black) X-rays foreign bodies are detectable by the collapse of lung parenchyma beyond them
  • G: great vessels, gastric bubble
    • Gastric bubble:
      • Should be present on left side under diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy
      • Absence points to GI pathology.
  • H: hilum Hilum Lungs: Anatomy
    • Calcifications
    • Malformation of blood vessels
    • Masses
  • I: general impression
    • Is there anything abnormal not explained by the patient’s pathologic condition?

Computed Tomography

Indication

Medical indications:

  • Follow-up of suspicious chest X-ray Chest X-ray X-ray visualization of the chest and organs of the thoracic cavity. It is not restricted to visualization of the lungs. Pulmonary Function Tests imaging:
    • Mediastinal widening
    • Suspected pulmonary mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast
    • Atypical pneumonia Atypical pneumonia Mycoplasma
    • ARDS ARDS Acute respiratory distress syndrome is characterized by the sudden onset of hypoxemia and bilateral pulmonary edema without cardiac failure. Sepsis is the most common cause of ARDS. The underlying mechanism and histologic correlate is diffuse alveolar damage (DAD). Acute Respiratory Distress Syndrome (ARDS)
    • Concern for intravascular pathology
  • Malignancy Malignancy Hemothorax:
  • Major trauma:
    • Evaluation of neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess and thoracic spine Spine The human spine, or vertebral column, is the most important anatomical and functional axis of the human body. It consists of 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae and is limited cranially by the skull and caudally by the sacrum. Vertebral Column: Anatomy
    • Concern for subtle pathology not seen on X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests

Advantages:

  • Excellent anatomical detail resolution 
  • Structures can be seen in 3 dimensions.
  • Often gold standard for pulmonary examination Pulmonary examination The pulmonary examination is a portion of the physical examination involving the assessment of the lungs and airways by a healthcare worker to evaluate for signs of disease or illness. The examination includes inspection, auscultation, percussion, and palpation. Pulmonary Examination

Disadvantages:

  • Involves high radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma dose
  • Not ubiquitously available
  • Patient must hold still for exam.
  • Expensive to perform

Exam technique

Ct scan device

Photograph of CT scanner:
The motorized table Motorized Table Computed Tomography (CT) moves the patient through the scanner, which contains the X-ray tube X-Ray Tube X-rays and detectors.

Image: “UPMCEast CTscan” by daveynin. License: CC BY 2.0

Standard CT scanning Standard CT scanning Imaging of the Liver and Biliary Tract:

  • Patient lies supine on table. 
  • Table is moved in CT scanner, which rotates around patient.
  • Patient is instructed to hold breath and remain still for scan (seconds).
  • Exams can be done with or without IV or oral contrast.
  • Timing of IV contrast dye can help direct radiologic inquiry for certain areas of lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy:
    • CT angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery: Pulmonary blood vessels are visible.
    • CT with IV contrast: for aortic enhancement (e.g., dissection protocols) or for organ enhancement (e.g., preferred in trauma to detect active bleeding)

Special forms:

  • High-resolution CT of chest:
    • Does not use contrast
    • Perform 3-dimensional (3D) reconstructions for additional imaging method and assistance in CT-guided surgeries
  • CT pulmonary angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery:
    • Used to obtain details of pulmonary arterial system
  • CT angiography Angiography Radiography of blood vessels after injection of a contrast medium. Cardiac Surgery or aortography:
    • Used to obtain details of arterial system
    • Requires a rapid infusion of contrast dye

Interpretation and evaluation

  • Interpretation should follow systematic and reproducible pattern.
  • Select appropriate window view for tissue evaluated:
    • Lung
    • Bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types
    • Mediastinal
  • Review patient’s history/examination.
  • Compare to available recent imaging of area of interest.
  • Orient image:
  • Identify landmark anatomical structures.
  • Observe for “continuity” of structures while scrolling through image slices.

Normal findings

  • Pulmonary tissue:
    • Uniformly dark gray tending toward black
    • Minor and major fissures of the right lobe and major fissure Fissure A crack or split that extends into the dermis Generalized and Localized Rashes of left lobe visible
  • Airways:
    • Larynx Larynx The larynx, also commonly called the voice box, is a cylindrical space located in the neck at the level of the C3-C6 vertebrae. The major structures forming the framework of the larynx are the thyroid cartilage, cricoid cartilage, and epiglottis. The larynx serves to produce sound (phonation), conducts air to the trachea, and prevents large molecules from reaching the lungs. Larynx: Anatomy, trachea Trachea The trachea is a tubular structure that forms part of the lower respiratory tract. The trachea is continuous superiorly with the larynx and inferiorly becomes the bronchial tree within the lungs. The trachea consists of a support frame of semicircular, or C-shaped, rings made out of hyaline cartilage and reinforced by collagenous connective tissue. Trachea: Anatomy, and bronchi Bronchi The larger air passages of the lungs arising from the terminal bifurcation of the trachea. They include the largest two primary bronchi which branch out into secondary bronchi, and tertiary bronchi which extend into bronchioles and pulmonary alveoli. Bronchial Tree: Anatomy are visible as black air-filled spaces.
    • Smaller 
  • Heart:
    • All 4 chambers visible 
    • Pericardium Pericardium A conical fibroserous sac surrounding the heart and the roots of the great vessels (aorta; venae cavae; pulmonary artery). Pericardium consists of two sacs: the outer fibrous pericardium and the inner serous pericardium. The latter consists of an outer parietal layer facing the fibrous pericardium, and an inner visceral layer (epicardium) resting next to the heart, and a pericardial cavity between these two layers. Heart: Anatomy should not be distinguishable in healthy individuals.
  • Blood vessels:
  • Bony structures:
    • Ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy, vertebrae, clavicles, scapulae, and humeri should be visible and lightest in color (most dense structures).
  • Abdominal structures:
    • Diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy should be visible dividing lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy from viscera.
    • Liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy should be visible, uniformly colored, with the exception of vasculature, under right hemidiaphragm.
    • Gastric bubble, bowel visible under left hemidiaphragm.

Pathologic findings

  • Pulmonary parenchyma:
    • Opacity:
      • Suggests consolidation Consolidation Pulmonary Function Tests/infection
      • Usually also visible on X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests 
      • CT allows for better anatomical localization (e.g., lobar, diffuse, dependent) and qualification (e.g., patchy, loculated).
    • Loss of lung volume ( atelectasis Atelectasis Atelectasis is the partial or complete collapse of a part of the lung. Atelectasis is almost always a secondary phenomenon from conditions causing bronchial obstruction, external compression, surfactant deficiency, or scarring. Atelectasis):
    • Hyperinflation:
      • Destruction of tissue distal to terminal bronchiole
      • Most commonly seen in emphysema Emphysema Enlargement of air spaces distal to the terminal bronchioles where gas-exchange normally takes place. This is usually due to destruction of the alveolar wall. Pulmonary emphysema can be classified by the location and distribution of the lesions. Chronic Obstructive Pulmonary Disease (COPD)
      • CT is more sensitive than X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests for diagnosis and allows for better qualification of disease.
    • Nodules and malignancies:
      • Nodules < 1 cm in diameter are not reliably evaluated by radiography.
      • CT allows for detailed evaluation and follow-up monitoring.
      • Calcifications, location, and size all help distinguish benign Benign Fibroadenoma lesions from more worrisome pathology.
  • Pulmonary interstitium:
    • Multiple etiologies, including viral infection and chemotherapy Chemotherapy Osteosarcoma
    • Reticular, nodular, or reticulonodular pattern
    • CT allows for better characterization of pattern than X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests.
  • Pleura Pleura The pleura is a serous membrane that lines the walls of the thoracic cavity and the surface of the lungs. This structure of mesodermal origin covers both lungs, the mediastinum, the thoracic surface of the diaphragm, and the inner part of the thoracic cage. The pleura is divided into a visceral pleura and parietal pleura. Pleura: Anatomy and pericardium Pericardium A conical fibroserous sac surrounding the heart and the roots of the great vessels (aorta; venae cavae; pulmonary artery). Pericardium consists of two sacs: the outer fibrous pericardium and the inner serous pericardium. The latter consists of an outer parietal layer facing the fibrous pericardium, and an inner visceral layer (epicardium) resting next to the heart, and a pericardial cavity between these two layers. Heart: Anatomy:
    • CT allows for detailed qualification and provides landmarks for treatment.
    • Free air between membranes appears dark.
    • Fluid in membrane will appear different shades depending on etiology.
  • Great vessels:
    • Aortic dissection Aortic dissection Aortic dissection occurs due to shearing stress from pulsatile pressure causing a tear in the tunica intima of the aortic wall. This tear allows blood to flow into the media, creating a “false lumen.” Aortic dissection is most commonly caused by uncontrolled hypertension. Aortic Dissection and aneurysm Aneurysm An aneurysm is a bulging, weakened area of a blood vessel that causes an abnormal widening of its diameter > 1.5 times the size of the native vessel. Aneurysms occur more often in arteries than in veins and are at risk of dissection and rupture, which can be life-threatening. Thoracic Aortic Aneurysms:
      • Contrast CT is method of choice.
      • Double lumen is visible on image.
    • Pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism:
      • Contrast CT is method of choice.
      • Filling defect is visible on image.

Magnetic Resonance Imaging

Indication

Medical indications:

  • Detailed evaluation of soft tissue Soft Tissue Soft Tissue Abscess organ structures:
    • Thymus Thymus A single, unpaired primary lymphoid organ situated in the mediastinum, extending superiorly into the neck to the lower edge of the thyroid gland and inferiorly to the fourth costal cartilage. It is necessary for normal development of immunologic function early in life. By puberty, it begins to involute and much of the tissue is replaced by fat. Lymphatic Drainage System: Anatomy 
    • Myocardium Myocardium The muscle tissue of the heart. It is composed of striated, involuntary muscle cells connected to form the contractile pump to generate blood flow. Heart: Anatomy 
  • Vascular disease:
  • Evaluation of chest wall Chest wall The chest wall consists of skin, fat, muscles, bones, and cartilage. The bony structure of the chest wall is composed of the ribs, sternum, and thoracic vertebrae. The chest wall serves as armor for the vital intrathoracic organs and provides the stability necessary for the movement of the shoulders and arms. Chest Wall: Anatomy:
    • Infection
    • Tumor Tumor Inflammation
    • Disease extending into or from pleura Pleura The pleura is a serous membrane that lines the walls of the thoracic cavity and the surface of the lungs. This structure of mesodermal origin covers both lungs, the mediastinum, the thoracic surface of the diaphragm, and the inner part of the thoracic cage. The pleura is divided into a visceral pleura and parietal pleura. Pleura: Anatomy
  • Evaluation of paraspinal masses:
    • Superior to CT because spinal bone Bone Bone is a compact type of hardened connective tissue composed of bone cells, membranes, an extracellular mineralized matrix, and central bone marrow. The 2 primary types of bone are compact and spongy. Bones: Structure and Types can create CT artifact

Advantages:

  • Provides higher level of imaging and detail of internal organs, bones, soft tissue Soft Tissue Soft Tissue Abscess, and blood vessels than chest X-ray Chest X-ray X-ray visualization of the chest and organs of the thoracic cavity. It is not restricted to visualization of the lungs. Pulmonary Function Tests or CT
  • Can be used for evaluation of pregnant patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship
  • Used as adjunct to previous test

Disadvantages:

  • ↑↑↑ Cost
  • Takes much longer to perform than chest X-ray Chest X-ray X-ray visualization of the chest and organs of the thoracic cavity. It is not restricted to visualization of the lungs. Pulmonary Function Tests or even CT
  • Not suitable for all patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship:
    • Implants (particularly metal ones) distort image.
    • Requires patient to be in loud, enclosed space.
    • Patient must stay still to allow for adequate images.

Exam technique

Positioning:

  • Supine on table
  • Table is advanced into scanner.
  • Patient is instructed to remain still for scan.
  • MRI scanner rotates around patient.

MRA MRA Imaging of the Heart and Great Vessels:

  • To examine blood vessels
  • Exams can be done with or without IV contrast.
  • Advancements have allowed medicine to create both 2D and 3D image reconstructions.

Views:

  • T1-weighted scans: Tissues with high fat content (e.g., white matter White Matter The region of central nervous system that appears lighter in color than the other type, gray matter. It mainly consists of myelinated nerve fibers and contains few neuronal cell bodies or dendrites. Brown-Séquard Syndrome) appear bright/white and compartments filled with water (CSF) appear dark/black.
  • T2-weighted scans: Compartments filled with water (CSF) appear bright/white and tissues with high fat content (e.g., white matter White Matter The region of central nervous system that appears lighter in color than the other type, gray matter. It mainly consists of myelinated nerve fibers and contains few neuronal cell bodies or dendrites. Brown-Séquard Syndrome) appear dark/black.
  • Images oriented in 3D slices: 

Interpretation and evaluation

  • Interpretation should follow a systematic and reproducible pattern.
  • Review patient’s history/examination.
  • Compare to available recent imaging of the area of interest.
  • Orient image.
  • Identify landmark anatomical structures.
  • Observe for “continuity” of structures while scrolling through image slices.

Normal findings

  • Thymus Thymus A single, unpaired primary lymphoid organ situated in the mediastinum, extending superiorly into the neck to the lower edge of the thyroid gland and inferiorly to the fourth costal cartilage. It is necessary for normal development of immunologic function early in life. By puberty, it begins to involute and much of the tissue is replaced by fat. Lymphatic Drainage System: Anatomy:
    • Size:
      • Largest in ages 12–19 years, then involutes
      • Round soft tissue Soft Tissue Soft Tissue Abscess masses 7 mm MM Multiple myeloma (MM) is a malignant condition of plasma cells (activated B lymphocytes) primarily seen in the elderly. Monoclonal proliferation of plasma cells results in cytokine-driven osteoclastic activity and excessive secretion of IgG antibodies. Multiple Myeloma after age 19
    • Shape:
  • Myocardium Myocardium The muscle tissue of the heart. It is composed of striated, involuntary muscle cells connected to form the contractile pump to generate blood flow. Heart: Anatomy:
    • Statistically normal parameters:
      • Muscle thickness
      • Ventricular size
      • End diastolic volume
  • Detailed anatomy of soft tissue Soft Tissue Soft Tissue Abscess structures:
    • Spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord: Anatomy
    • Pulmonary parenchyma
    • Diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy
    • Top of liver Liver The liver is the largest gland in the human body. The liver is found in the superior right quadrant of the abdomen and weighs approximately 1.5 kilograms. Its main functions are detoxification, metabolism, nutrient storage (e.g., iron and vitamins), synthesis of coagulation factors, formation of bile, filtration, and storage of blood. Liver: Anatomy
    • Vasculature

Pathologic findings

  • Thymus Thymus A single, unpaired primary lymphoid organ situated in the mediastinum, extending superiorly into the neck to the lower edge of the thyroid gland and inferiorly to the fourth costal cartilage. It is necessary for normal development of immunologic function early in life. By puberty, it begins to involute and much of the tissue is replaced by fat. Lymphatic Drainage System: Anatomy:
  • Myocardium Myocardium The muscle tissue of the heart. It is composed of striated, involuntary muscle cells connected to form the contractile pump to generate blood flow. Heart: Anatomy:
    • Changes in size, shape, or thickness:
      • Myocarditis Myocarditis Myocarditis is an inflammatory disease of the myocardium, which may occur alone or in association with a systemic process. There are numerous etiologies of myocarditis, but all lead to inflammation and myocyte injury, most often leading to signs and symptoms of heart failure. Myocarditis
      • Cardiac Cardiac Total Anomalous Pulmonary Venous Return (TAPVR) sarcoidosis Sarcoidosis Sarcoidosis is a multisystem inflammatory disease that causes noncaseating granulomas. The exact etiology is unknown. Sarcoidosis usually affects the lungs and thoracic lymph nodes, but it can also affect almost every system in the body, including the skin, heart, and eyes, most commonly. Sarcoidosis
      • Takotsubo cardiomyopathy Takotsubo Cardiomyopathy Takotsubo cardiomyopathy (also known as stress cardiomyopathy, or “broken heart syndrome”) is a type of non-ischemic cardiomyopathy in which there is transient regional systolic dysfunction of the left ventricle. Patients present with symptoms of acute coronary syndrome, including chest pressure and shortness of breath. Takotsubo Cardiomyopathy
      • MI MI MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction with nonobstructed coronary arteries Arteries Arteries are tubular collections of cells that transport oxygenated blood and nutrients from the heart to the tissues of the body. The blood passes through the arteries in order of decreasing luminal diameter, starting in the largest artery (the aorta) and ending in the small arterioles. Arteries are classified into 3 types: large elastic arteries, medium muscular arteries, and small arteries and arterioles. Arteries: Histology (MINOCA)
      • Cardiomyopathies Cardiomyopathies A group of diseases in which the dominant feature is the involvement of the cardiac muscle itself. Cardiomyopathies are classified according to their predominant pathophysiological features (dilated cardiomyopathy; hypertrophic cardiomyopathy; restrictive cardiomyopathy) or their etiological/pathological factors (cardiomyopathy, alcoholic; endocardial fibroelastosis). Cardiomyopathy: Overview and Types
  • Blood vessels:
    • Double-lumen sign:
      • Aortic dissection Aortic dissection Aortic dissection occurs due to shearing stress from pulsatile pressure causing a tear in the tunica intima of the aortic wall. This tear allows blood to flow into the media, creating a “false lumen.” Aortic dissection is most commonly caused by uncontrolled hypertension. Aortic Dissection
    • Change in pulmonary vein Pulmonary Vein Total Anomalous Pulmonary Venous Return (TAPVR) diameter:
      • Pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension (PH) or pulmonary arterial hypertension (PAH) is characterized by elevated pulmonary arterial pressure, which can lead to chronic progressive right heart failure. Pulmonary hypertension is grouped into 5 categories based on etiology, which include primary PAH, and PH due to cardiac disease, lung or hypoxic disease, chronic thromboembolic disease, and multifactorial or unclear etiologies. Pulmonary Hypertension

Mnemonic

MRI T2 = H20 is white

Ultrasonography

Indication

Medical indications:

  • Imaging of areas filled with fluid:
    • Ascites Ascites Ascites is the pathologic accumulation of fluid within the peritoneal cavity that occurs due to an osmotic and/or hydrostatic pressure imbalance secondary to portal hypertension (cirrhosis, heart failure) or non-portal hypertension (hypoalbuminemia, malignancy, infection). Ascites
    • Edema Edema Edema is a condition in which excess serous fluid accumulates in the body cavity or interstitial space of connective tissues. Edema is a symptom observed in several medical conditions. It can be categorized into 2 types, namely, peripheral (in the extremities) and internal (in an organ or body cavity). Edema
  • Imaging when radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma is contraindicated:
  • Specific settings include:
    • Trauma
    • Suspected infection of the lung parenchyma and pleura Pleura The pleura is a serous membrane that lines the walls of the thoracic cavity and the surface of the lungs. This structure of mesodermal origin covers both lungs, the mediastinum, the thoracic surface of the diaphragm, and the inner part of the thoracic cage. The pleura is divided into a visceral pleura and parietal pleura. Pleura: Anatomy
    • Evaluation of cardiac Cardiac Total Anomalous Pulmonary Venous Return (TAPVR) anatomy and function
    • Procedural

Advantages:

  • Can be performed at the bedside
  • Fast to perform
  • Low cost
  • No exposure Exposure ABCDE Assessment to ionizing radiation Radiation Emission or propagation of acoustic waves (sound), electromagnetic energy waves (such as light; radio waves; gamma rays; or x-rays), or a stream of subatomic particles (such as electrons; neutrons; protons; or alpha particles). Osteosarcoma
  • Works well for imaging soft tissue Soft Tissue Soft Tissue Abscess

Disadvantages:

  • Quality Quality Activities and programs intended to assure or improve the quality of care in either a defined medical setting or a program. The concept includes the assessment or evaluation of the quality of care; identification of problems or shortcomings in the delivery of care; designing activities to overcome these deficiencies; and follow-up monitoring to ensure effectiveness of corrective steps. Quality Measurement and Improvement depends on the experience of the user.
  • Image resolution can vary.

Exam technique

  • Transthoracic:
    • Probe Probe A device placed on the patient’s body to visualize a target Ultrasound (Sonography) is placed on external chest wall Chest wall The chest wall consists of skin, fat, muscles, bones, and cartilage. The bony structure of the chest wall is composed of the ribs, sternum, and thoracic vertebrae. The chest wall serves as armor for the vital intrathoracic organs and provides the stability necessary for the movement of the shoulders and arms. Chest Wall: Anatomy over area of interest.
    • Ultrasound beam is oriented to desired anatomy.
  • Transesophageal:
    • Probe Probe A device placed on the patient’s body to visualize a target Ultrasound (Sonography) is placed in patient’s esophagus Esophagus The esophagus is a muscular tube-shaped organ of around 25 centimeters in length that connects the pharynx to the stomach. The organ extends from approximately the 6th cervical vertebra to the 11th thoracic vertebra and can be divided grossly into 3 parts: the cervical part, the thoracic part, and the abdominal part. Esophagus: Anatomy.
    • Allows for closer imaging of mediastinal structures 
  • Imaging planes:
  • Types of images:
  • Image definition or sharpness of image generated can be characterized in terms of:
    • Axial Axial Computed Tomography (CT) definition: 
      • Differentiation of 2 objects close to each other, parallel to beam
      • Determines depth of ultrasound beam; quality Quality Activities and programs intended to assure or improve the quality of care in either a defined medical setting or a program. The concept includes the assessment or evaluation of the quality of care; identification of problems or shortcomings in the delivery of care; designing activities to overcome these deficiencies; and follow-up monitoring to ensure effectiveness of corrective steps. Quality Measurement and Improvement impacted by beam penetration Penetration X-rays
    • Lateral definition Lateral definition Differentiation of 2 objects on a plane perpendicular to the beam Ultrasound (Sonography)
      • Differentiation of 2 objects on plane perpendicular to beam
      • Determines ability of probe Probe A device placed on the patient’s body to visualize a target Ultrasound (Sonography) to distinguish structures perpendicular to beam
      • Primarily determined by beam width

Interpretation and evaluation

  • Interpretation of ultrasounds is challenging even for trained practitioners.
  • Should follow systematic and reproducible pattern
  • Review patient’s history/examination.
  • Compare to available recent imaging of area of interest.
  • Fluid appears dark on ultrasound.
  • Doppler Doppler Ultrasonography applying the doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. Ultrasound (Sonography) functionality can be used to determine flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure of blood.

Normal findings

  • Lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy:
    • Ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy appear white.
    • Pleura Pleura The pleura is a serous membrane that lines the walls of the thoracic cavity and the surface of the lungs. This structure of mesodermal origin covers both lungs, the mediastinum, the thoracic surface of the diaphragm, and the inner part of the thoracic cage. The pleura is divided into a visceral pleura and parietal pleura. Pleura: Anatomy (located just deep to ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy) is dark.
    • Multiple reflections of pleura Pleura The pleura is a serous membrane that lines the walls of the thoracic cavity and the surface of the lungs. This structure of mesodermal origin covers both lungs, the mediastinum, the thoracic surface of the diaphragm, and the inner part of the thoracic cage. The pleura is divided into a visceral pleura and parietal pleura. Pleura: Anatomy are seen as equally spaced horizontal lines (A-lines)
    • Lung sliding seen as patient breathes.
  • Heart:
    • Anatomy:
      • Myocardium Myocardium The muscle tissue of the heart. It is composed of striated, involuntary muscle cells connected to form the contractile pump to generate blood flow. Heart: Anatomy
      • Valves
      • Chambers
    • Function:
      • Wall movement is coordinated.
      • Systolic and diastolic function appropriate
      • Flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure through chambers and coronaries unimpeded
Normal lung ultrasound

Normal lung ultrasound:
(A): The pleural lines (arrows): The A-lines, or horizontal lines arising from the pleural line, are separated by regular Regular Insulin intervals that are equal to the distance between the skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions and the pleural line.
(B): M-mode M-Mode Imaging of the Heart and Great Vessels shows the pleural line. Under the pleural line is the seashore sign (sandy pattern) due to the lung dynamics and pleural sliding. The horizontal lines are A-lines, separated by regular Regular Insulin intervals (arrows).

Image: “Normal lung ultrasound” by Department of Critical Care, University Medical Center Groningen, University of Groningen, Hanzeplein 1, Groningen, 9700 RB RB Chlamydia, The Netherlands. License: CC BY 2.0

Pathologic findings

  • Lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy:
    • Pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion:
    • Pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax:
      • Absent lung sliding
      • Absent lung pulse
  • Heart:
    • Anatomy:
      • Congenital Congenital Chorioretinitis abnormalities
      • Cardiac Cardiac Total Anomalous Pulmonary Venous Return (TAPVR) remodeling after MI MI MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction
      • Cardiomyopathy Cardiomyopathy Cardiomyopathy refers to a group of myocardial diseases associated with structural changes of the heart muscles (myocardium) and impaired systolic and/or diastolic function in the absence of other heart disorders (coronary artery disease, hypertension, valvular disease, and congenital heart disease). Cardiomyopathy: Overview and Types
    • Function:
      • Systolic or diastolic insufficiency
    • Flow Flow Blood flows through the heart, arteries, capillaries, and veins in a closed, continuous circuit. Flow is the movement of volume per unit of time. Flow is affected by the pressure gradient and the resistance fluid encounters between 2 points. Vascular resistance is the opposition to flow, which is caused primarily by blood friction against vessel walls. Vascular Resistance, Flow, and Mean Arterial Pressure:
  • Procedural

Clinical Correlation

Pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia

  • Can be seen on X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests, CT, or MRI
  • Consolidation Consolidation Pulmonary Function Tests (unilateral or bilateral):
    • Lobar pattern
    • Ground-glass pattern
    • Reticular or reticulonodular pattern
  • +/– Air bronchograms, blunted costophrenic angle
  • +/– Cavitation: round radiolucency Radiolucency Chondrosarcoma surrounded by opacification
  • +/– Abscess Abscess Accumulation of purulent material in tissues, organs, or circumscribed spaces, usually associated with signs of infection. Chronic Granulomatous Disease formation: air-fluid level

Malignancy Malignancy Hemothorax

  • Mass Mass Three-dimensional lesion that occupies a space within the breast Imaging of the Breast in lung tissue on chest radiology
  • Can be seen on X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests, CT, or MRI
  • Number:
  • Size: 
  • Spiculated margins are usual.
  • +/– Cavitation, calcifications, effusion, atelectasis Atelectasis Atelectasis is the partial or complete collapse of a part of the lung. Atelectasis is almost always a secondary phenomenon from conditions causing bronchial obstruction, external compression, surfactant deficiency, or scarring. Atelectasis, and hilar lymphadenopathy Lymphadenopathy Lymphadenopathy is lymph node enlargement (> 1 cm) and is benign and self-limited in most patients. Etiologies include malignancy, infection, and autoimmune disorders, as well as iatrogenic causes such as the use of certain medications. Generalized lymphadenopathy often indicates underlying systemic disease. Lymphadenopathy

Pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax

  • CT and MRI are more sensitive than X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests.
  • Visceral pleural white line: absence of lung markings peripheral to it
  • Deep sulcus sign Deep Sulcus Sign Pneumothorax: inferiorly displaced, lucent costophrenic angle 
  • Simple pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax: no mediastinal shift
  • Tension pneumothorax Tension Pneumothorax Pneumothorax:
    • Mediastinal shift away from lucency
    • Compressed contralateral lung

Emphysema Emphysema Enlargement of air spaces distal to the terminal bronchioles where gas-exchange normally takes place. This is usually due to destruction of the alveolar wall. Pulmonary emphysema can be classified by the location and distribution of the lesions. Chronic Obstructive Pulmonary Disease (COPD)

  • Seen on chest X-ray Chest X-ray X-ray visualization of the chest and organs of the thoracic cavity. It is not restricted to visualization of the lungs. Pulmonary Function Tests, CT, and MRI
  • Hyperinflated lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy:
    • Flattened diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy
    • Hyperlucency 
    • ↑ AP diameter of chest
    • Widely spaced ribs Ribs A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage. Together, they form a protective cage around the internal thoracic organs. Chest Wall: Anatomy
    • Narrow mediastinum Mediastinum The mediastinum is the thoracic area between the 2 pleural cavities. The mediastinum contains vital structures of the circulatory, respiratory, digestive, and nervous systems including the heart and esophagus, and major thoracic vessels. Mediastinum and Great Vessels: Anatomy
  • +/– Bullae Bullae Erythema Multiforme

Pleural effusion Pleural Effusion Pleural effusion refers to the accumulation of fluid between the layers of the parietal and visceral pleura. Common causes of this condition include infection, malignancy, autoimmune disorders, or volume overload. Clinical manifestations include chest pain, cough, and dyspnea. Pleural Effusion

  • Seen on chest X-ray Chest X-ray X-ray visualization of the chest and organs of the thoracic cavity. It is not restricted to visualization of the lungs. Pulmonary Function Tests, CT, MRI, and ultrasonography (US)
  • Fluid above diaphragm Diaphragm The diaphragm is a large, dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. The diaphragm consists of muscle fibers and a large central tendon, which is divided into right and left parts. As the primary muscle of inspiration, the diaphragm contributes 75% of the total inspiratory muscle force. Diaphragm: Anatomy:
    • Appears black on US
    • White (hypodense) on CT and X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests
    • On T2 MRI, water appears bright.
    • On T1 MRI, water appears dark.
  • Supine, upright, and decubitus projections can be used for X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests.
  • On upright X-ray X-ray Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release radiant energy. X-ray wavelengths range from 1 pm to 10 nm. Hard x-rays are the higher energy, shorter wavelength x-rays. Soft x-rays or grenz rays are less energetic and longer in wavelength. The short wavelength end of the x-ray spectrum overlaps the gamma rays wavelength range. The distinction between gamma rays and x-rays is based on their radiation source. Pulmonary Function Tests:
    • Blunted costophrenic angle
    • Meniscus sign
  • Complete hemithorax opacification can occur +/– mediastinal shifting to other side
  • Sinusoid Sinusoid Sinusoid, or discontinuous, capillaries allow larger proteins and full cells to pass through larger gaps. Capillaries: Histology sign on US: Lung moves within pleural fluid, seen on real-time examination.

Pulmonary edema Pulmonary edema Pulmonary edema is a condition caused by excess fluid within the lung parenchyma and alveoli as a consequence of a disease process. Based on etiology, pulmonary edema is classified as cardiogenic or noncardiogenic. Patients may present with progressive dyspnea, orthopnea, cough, or respiratory failure. Pulmonary Edema

  • Seen on chest X-ray Chest X-ray X-ray visualization of the chest and organs of the thoracic cavity. It is not restricted to visualization of the lungs. Pulmonary Function Tests, CT, and MRI
  • Interstitial/parenchymal fluid in lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy
  • Consolidation Consolidation Pulmonary Function Tests on imaging, usually bilateral
  • +/– Air bronchograms, prominent lung vascularity, enlarged heart, Kerley A and B lines, and pleural effusions
  • Classic bat-wing appearance from cephalization of pulmonary vasculature and fluid buildup

Atelectasis Atelectasis Atelectasis is the partial or complete collapse of a part of the lung. Atelectasis is almost always a secondary phenomenon from conditions causing bronchial obstruction, external compression, surfactant deficiency, or scarring. Atelectasis

References

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