Pediatric Chest Abnormalities

Radiography

Indication

• Medical indications:
  • Emergency care:
    • Trauma with concern for chest injury
    • Concern for foreign body aspiration Foreign body aspiration Foreign body aspiration can lead to choking and death by obstructing airflow at the larynx or trachea. Foreign bodies may also become lodged deeper in the bronchi; this may not affect breathing but can cause infection or erosion of bronchial walls. Foreign Body Aspiration
    • Acute severe respiratory compromise
  • Routine care:
    • Screening Screening Preoperative Care for individuals with low APGAR scores at birth
    • Confirming line/ tube placement Tube placement Surgical procedure involving the creation of an opening (stoma) into the chest cavity for drainage; used in the treatment of pleural effusion; pneumothorax; hemothorax; and empyema. Thoracic Surgery
  • Monitoring:
    • Known pneumothoraces and evaluation for progression or regression Regression Corneal Abrasions, Erosion, and Ulcers
    • Heart size in known congenital Congenital Chorioretinitis heart disease (usually in combination with echocardiography Echocardiography Ultrasonic recording of the size, motion, and composition of the heart and surrounding tissues. The standard approach is transthoracic. Tricuspid Valve Atresia (TVA))
• 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 
  • Widespread availability
  • Fast
• Disadvantages:
  • Involves 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 
  • Individual must hold still during imaging
  • Image 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 and interpretation are technician and physician dependent.

Exam technique

• Positioning:
  • Upright, supine, and/or decubitus positioning (dependent on the suspected pathology and clinical indication)
  • The technician optimizes individual positioning relative to the 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 source and detector.
  • Timing of images during the inspiratory phase of the respiratory cycle is generally preferred.
• Visualization:
  • Vertebral bodies: slightly visible through the 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
  • 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 (less suggest hypoinflation, more suggest hyperinflation Hyperinflation Imaging of the Lungs and Pleura) 
  • Interstitial markings: present without oversaturation
  • Removal of jewelry, brassiere, or other high density materials is necessary.
• Other: Lead shielding is no longer recommended (recent developments demonstrate shielding leads to increased dosing delivered to the individual).

Interpretation/evaluation

Systematic approach: 

• “Outside-in” approach (peripheral to central):
  • Look at soft tissues for gas or high-density foreign bodies.
  • Review bones (e.g., clavicles, vertebral bodies, scapula, humerus Humerus Bone in humans and primates extending from the shoulder joint to the elbow joint. Arm: Anatomy).
  • Trace tracheal airway Airway ABCDE Assessment into right and left mainstem 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.
  • Evaluate the heart size and cardiac contour.
  • Follow aorta Aorta The main trunk of the systemic arteries. Mediastinum and Great Vessels: Anatomy/pulmonary vasculature (evaluate left- vs. right-sided arch).
  • Evaluate mediastinal width (neonates have a large 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 for given mediastinal volume).
  • Review the bilateral lung fields (individually and comparatively).

Normal findings

Anteroposterior (AP) view:

• Organs:
  • Heart size: variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables and dependent on the individual’s age, occupying a larger percentage of the chest volume as a neonate Neonate An infant during the first 28 days after birth. Physical Examination of the Newborn and gradually decreasing over time, but not occupying a space wider than ½ the 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
  • 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: inflated and bilaterally symmetric
  • 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: visible as a neonate Neonate An infant during the first 28 days after birth. Physical Examination of the Newborn and gradually decreases in size with age
  • Aorta Aorta The main trunk of the systemic arteries. Mediastinum and Great Vessels: Anatomy: left side of the 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 an appropriate size for the individual’s age
• Lung 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:
  • Clear with minimal lung markings
  • Sharp costophrenic angles
• Bones:
  • Pedicles: present and bilaterally symmetric
  • Spinous processes: midline
  • Clavicles and acromioclavicular joints: without fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures or joint widening/craniocaudal offset
  • 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: without fracture Fracture A fracture is a disruption of the cortex of any bone and periosteum and is commonly due to mechanical stress after an injury or accident. Open fractures due to trauma can be a medical emergency. Fractures are frequently associated with automobile accidents, workplace injuries, and trauma. Overview of Bone Fractures and no evidence of inferior notching (would be seen with coarctation of the aorta Coarctation of the aorta Coarctation of the aorta is a narrowing of the aorta between the aortic arch and the iliac bifurcation commonly around the point of insertion of the ductus arteriosus. Coarctation of the aorta is typically congenital and the clinical presentation depends on the age of the patient. Coarctation of the Aorta)

Transient tachypnea Tachypnea Increased respiratory rate. Pulmonary Examination of the newborn Newborn An infant during the first 28 days after birth. Physical Examination of the Newborn

• Etiology:
  • Affects newborns (term or late preterm) shortly after delivery
  • The most common cause of respiratory distress in term neonates
  • Delayed resorption of fluid in the fetal lung
  • Results in fluid accumulation in the lymphatics and vascular bed 
  • Often seen with cesarean delivery due to a lack of the “thoracic squeeze”, which expels pulmonary fluid and normally occurs during vaginal delivery
• Presentation:
  • Early onset (within hours of birth): nasal flaring and tachypnea Tachypnea Increased respiratory rate. Pulmonary Examination (sometimes with retractions or expiratory grunting Grunting Physical Examination of the Newborn)
  • Mild cyanosis Cyanosis A bluish or purplish discoloration of the skin and mucous membranes due to an increase in the amount of deoxygenated hemoglobin in the blood or a structural defect in the hemoglobin molecule. Pulmonary Examination relieved by minimal oxygen

Meconium Meconium The thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the intestinal glands; bile pigments; fatty acids; amniotic fluid; and intrauterine debris. It constitutes the first stools passed by a newborn. Prenatal and Postnatal Physiology of the Neonate aspiration syndrome

• Occurs most frequently in term or postterm infants
• Occurs either in utero or, more often, with the 1st breath
• Thick and particulate meconium Meconium The thick green-to-black mucilaginous material found in the intestines of a full-term fetus. It consists of secretions of the intestinal glands; bile pigments; fatty acids; amniotic fluid; and intrauterine debris. It constitutes the first stools passed by a newborn. Prenatal and Postnatal Physiology of the Neonate is aspirated into 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, resulting in:
  • Small airway obstruction Airway obstruction Airway obstruction is a partial or complete blockage of the airways that impedes airflow. An airway obstruction can be classified as upper, central, or lower depending on location. Lower airway obstruction (LAO) is usually a manifestation of chronic disease, such as asthma or chronic obstructive pulmonary disease (COPD). Airway Obstruction and consequent respiratory distress within the 1st hour of birth
  • Partial obstruction of some airways may lead to 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 or pneumomediastinum Pneumomediastinum Mediastinitis
  • Can cause chemical pneumonitis Pneumonitis Human Herpesvirus 6 and 7 and result in severe respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure
• Radiograph findings:
  • 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
  • Flattening of the 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
  • Perihilar opacities
  • Patchy areas of consolidation Consolidation Pulmonary Function Tests

Hyaline membrane disease Hyaline membrane disease Respiratory distress syndrome (RDS), also known as hyaline membrane disease, is caused by the lack of adequate pulmonary surfactant production in an immature lung. The syndrome is most commonly seen in preterm infants. Neonatal Respiratory Distress Syndrome

• Also known as neonatal respiratory distress syndrome Neonatal Respiratory Distress Syndrome Respiratory distress syndrome (RDS), also known as hyaline membrane disease, is caused by the lack of adequate pulmonary surfactant production in an immature lung. The syndrome is most commonly seen in preterm infants. Neonatal Respiratory Distress Syndrome
• Secondary to an inability of the pneumocytes to produce surfactant Surfactant Substances and drugs that lower the surface tension of the mucoid layer lining the pulmonary alveoli. Acute Respiratory Distress Syndrome (ARDS):
  • Surfactant Surfactant Substances and drugs that lower the surface tension of the mucoid layer lining the pulmonary alveoli. Acute Respiratory Distress Syndrome (ARDS) plays a major role in surface tension Surface tension The force acting on the surface of a liquid, tending to minimize the area of the surface. Acute Respiratory Distress Syndrome (ARDS) reduction.
  • Deficiency leads to alveolar collapse.
• Radiograph findings:
  • Low lung volumes
  • Diffuse reticulogranular pattern (ground-glass appearance)
  • Air bronchograms Air Bronchograms Imaging of the Lungs and Pleura: outline of air-filled large airways against opaque 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

Epiglottitis Epiglottitis Epiglottitis (or “supraglottitis”) is an inflammation of the epiglottis and adjacent supraglottic structures. The majority of cases are caused by bacterial infection. Symptoms are rapid in onset and severe. Epiglottitis

• 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 and swelling Swelling Inflammation of the epiglottis Epiglottis A thin leaf-shaped cartilage that is covered with laryngeal mucosa and situated posterior to the root of the tongue and hyoid bone. During swallowing, the epiglottis folds back over the larynx inlet thus prevents foods from entering the airway. Larynx: Anatomy cause upper airway obstruction Airway obstruction Airway obstruction is a partial or complete blockage of the airways that impedes airflow. An airway obstruction can be classified as upper, central, or lower depending on location. Lower airway obstruction (LAO) is usually a manifestation of chronic disease, such as asthma or chronic obstructive pulmonary disease (COPD). Airway Obstruction.
• Etiology:
  • Haemophilus Haemophilus Haemophilus is a genus of Gram-negative coccobacilli, all of whose strains require at least 1 of 2 factors for growth (factor V [NAD] and factor X [heme]); therefore, it is most often isolated on chocolate agar, which can supply both factors. The pathogenic species are H. influenzae and H. ducreyi. Haemophilus influenzae (most common cause)
  • H. parainfluenzae
  • Streptococcus Streptococcus Streptococcus is one of the two medically important genera of gram-positive cocci, the other being Staphylococcus. Streptococci are identified as different species on blood agar on the basis of their hemolytic pattern and sensitivity to optochin and bacitracin. There are many pathogenic species of streptococci, including S. pyogenes, S. agalactiae, S. pneumoniae, and the viridans streptococci. Streptococcus pneumoniae
  • Group A streptococcus Group A Streptococcus A species of gram-positive, coccoid bacteria isolated from skin lesions, blood, inflammatory exudates, and the upper respiratory tract of humans. It is a group a hemolytic Streptococcus that can cause scarlet fever and rheumatic fever. Postinfectious Glomerulonephritis
• Radiographic findings:
  • The characteristic radiographic findings are only visible on lateral radiograph.
  • Thumbprint sign: a swollen and enlarged epiglottis Epiglottis A thin leaf-shaped cartilage that is covered with laryngeal mucosa and situated posterior to the root of the tongue and hyoid bone. During swallowing, the epiglottis folds back over the larynx inlet thus prevents foods from entering the airway. Larynx: Anatomy with a dilated hypopharynx

Croup Croup Croup, also known as laryngotracheobronchitis, is a disease most commonly caused by a viral infection that leads to severe inflammation of the upper airway. It usually presents in children < 5 years of age. Patients develop a hoarse, "seal-like" barking cough and inspiratory stridor. Croup

• Also known as laryngotracheobronchitis Laryngotracheobronchitis Croup, also known as laryngotracheobronchitis, is a disease most commonly caused by a viral infection that leads to severe inflammation of the upper airway. It usually presents in children < 5 years of age. Patients develop a hoarse, "seal-like" barking cough and inspiratory stridor. Croup
• Defined as an inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the 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 and 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, which may extend to the 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
• Mostly caused by a viral infection (e.g., parainfluenza virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology)
• Radiograph findings:
  • Lateral neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess radiograph: narrowing of the subglottic 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 distension of the hypopharynx
  • Frontal radiograph: inverted “V” appearance (steeple sign)

Foreign body aspiration Foreign body aspiration Foreign body aspiration can lead to choking and death by obstructing airflow at the larynx or trachea. Foreign bodies may also become lodged deeper in the bronchi; this may not affect breathing but can cause infection or erosion of bronchial walls. Foreign Body Aspiration

• Most commonly occurs in children from 6 months to 3 years of age:
  • Due to the tendency for children to place small objects in the mouth and nose Nose The nose is the human body’s primary organ of smell and functions as part of the upper respiratory system. The nose may be best known for inhaling oxygen and exhaling carbon dioxide, but it also contributes to other important functions, such as tasting. The anatomy of the nose can be divided into the external nose and the nasal cavity. Nose and Nasal Cavity: Anatomy
  • Choking history may be provided.
  • Individuals may present with cough.
• Aspirated foreign bodies often lodge in a bronchus, which functions as a 1-way valve and only permits air to enter the affected side:
  • Leads to asymmetric lung volumes
  • May cause 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
• Most foreign bodies settle in the right mainstem bronchus due to the anatomy:
  • Wider diameter
  • More vertical
• Radiograph findings:
  • Inspiratory chest radiograph: may be initially normal
  • Obtain expiratory and inspiratory films.
  • Bilateral decubitus views: Obtain in children who cannot cooperate.
  • Because of gravity, the lung in the lower position should decompress: The side of the abnormality is identified if the lung remains persistently hyperinflated and does not decompress.
  • Unless made of metal or other dense material, the aspirated foreign body Foreign Body Foreign Body Aspiration is often not visible and may be radiolucent Radiolucent An object of low density that is permeable to X-rays (looks black) X-rays.
  • Repeat or delayed radiographs may show asymmetric lung volumes.

Computed Tomography

Indications

• Medical indications:
  • Follow-up of suspicious radiographic/sonographic findings:
    • Concern for vascular pathology (e.g., double/right aortic arch Aortic arch Mediastinum and Great Vessels: Anatomy, vascular sling, malignant right coronary artery Coronary Artery Truncus Arteriosus)
    • Cardiomediastinal contour deformities
    • Segmental hyper/hypolucency in the lung
    • Concern for 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 
  • Malignancy Malignancy Hemothorax:
    • Evaluation and initial staging Staging Methods which attempt to express in replicable terms the extent of the neoplasm in the patient. Grading, Staging, and Metastasis studies 
    • Surveillance Surveillance Developmental Milestones and Normal Growth for recurrence of disease
    • Venous thrombosis Thrombosis Formation and development of a thrombus or blood clot in the blood vessel. Epidemic Typhus secondary to tumors
  • Major trauma:
    • Evaluation of lung parenchyma
    • Evaluation for cardiomediastinal hemorrhage +/- active extravasation on delayed images
    • Concern for subtle pathology not seen on ultrasound/radiograph
• Advantages:
  • Excellent anatomical detail resolution 
  • Structures can be seen in 3 dimensions
• Disadvantages:
  • Involves high dose of 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
  • Individual must hold still for the exam
  • Expensive to perform

Exam technique

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

• Individual lies supine on a table. 
• The table is moved into a CT scanner, which rotates around the individual.
• The individual is instructed to hold breath and remain still for the scan (young individuals may be unable to comply and require sedation).
• Exams can be done with or without IV or oral contrast.
• Timing of IV contrast dye can help direct radiology inquiry of certain areas of pathology: CT with IV contrast can be completed in pulmonary artery Pulmonary artery The short wide vessel arising from the conus arteriosus of the right ventricle and conveying unaerated blood to the lungs. Lungs: Anatomy, angiographic, or routine contrast timing.

Interpretation and evaluation

• Interpretation should follow a systematic and reproducible pattern.
• Review the individual’s history and examination.
• Soft tissue Soft Tissue Soft Tissue Abscess, lung, and 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 windows are utilized depending on pathophysiological process suspected.
• Compare to available recent imaging of the interested area.
• Orient image:
  • Axial Axial Computed Tomography (CT) images are seen as if looking up from the indivdual’s feet.
  • Acquire sagittal Sagittal Computed Tomography (CT) and coronal Coronal Computed Tomography (CT) planes.
• Identify landmark anatomical structures.
• Observe for “continuity” of parenchyma while scrolling through image slices.

Normal findings

Normal chest CT (findings may be dependent on the individual’s age):

• A 4-chamber heart with the ventricles larger than the atria, and the left side of the heart larger than the right side
• An aorta Aorta The main trunk of the systemic arteries. Mediastinum and Great Vessels: Anatomy arising from the left ventricle, coursing to the leftward side of the 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: 3-vessel arch (i.e., brachiocephalic artery, left common carotid artery Common carotid artery The two principal arteries supplying the structures of the head and neck. They ascend in the neck, one on each side, and at the level of the upper border of the thyroid cartilage, each divides into two branches, the external and internal carotid arteries. Carotid Arterial System: Anatomy, and left subclavian artery)
• The pulmonary trunk Pulmonary Trunk Truncus Arteriosus arises from the right ventricle with a left and right main pulmonary artery Pulmonary artery The short wide vessel arising from the conus arteriosus of the right ventricle and conveying unaerated blood to the lungs. Lungs: Anatomy and segmental/subsegmental branches.
• The left main coronary artery Coronary Artery Truncus Arteriosus arises from the left coronary cusp; the right coronary artery Coronary Artery Truncus Arteriosus arises from the right coronary cusp.
• 3 lobes of the right lung (i.e., right upper, right middle, and right lower); 2 lobes of the left lung (i.e., left upper and left lower)
• The 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 travels inferiorly and branches into the right and left mainstem 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 (the right mainstem is more vertical and slightly wider (important for aspiration risk)).
• The right mainstem becomes the right upper lobe bronchus and right intermediate bronchus (further branching to the right middle and lower lobe 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).
• The left mainstem bronchus becomes the left upper and lower lobe 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.
• The 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 (located in the anterior 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) can be visualized most prominently as a neonate Neonate An infant during the first 28 days after birth. Physical Examination of the Newborn and regresses with age.
• The 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 courses inferiorly in the posterior 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 to the level of the 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 and then becomes the 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.
• 12 thoracic vertebrae Thoracic vertebrae A group of twelve vertebrae connected to the ribs that support the upper trunk region. Vertebral Column: Anatomy with bilateral paired 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

Cystic Cystic Fibrocystic Change fibrosis Fibrosis Any pathological condition where fibrous connective tissue invades any organ, usually as a consequence of inflammation or other injury. Bronchiolitis Obliterans

Multiple CT correlated findings:

• Bronchiectasis Bronchiectasis Bronchiectasis is a chronic disease of the airways that results from permanent bronchial distortion. This results from a continuous cycle of inflammation, bronchial damage and dilation, impaired clearance of secretions, and recurrent infections. Bronchiectasis
• Mucous plugging
• Pneumothoraces
• Recurrent infection 
• Mosaic attenuation of the lung parenchyma (suggestive of air trapping)

Vascular sling/ring

A specific type of vascular anomaly involving partial or complete entrapment of the 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 or 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 by a vessel:

• 270 degree entrapment of the 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 by the left pulmonary artery Pulmonary artery The short wide vessel arising from the conus arteriosus of the right ventricle and conveying unaerated blood to the lungs. Lungs: Anatomy in a pulmonary sling
• Double aortic arch Double Aortic Arch Vascular Rings produces complete entrapment with narrowing of the 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/or aorta Aorta The main trunk of the systemic arteries. Mediastinum and Great Vessels: Anatomy.
• Posterior indentation of the 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 may be seen in cases of aberrant right subclavian artery Aberrant Right Subclavian Artery Imaging of the Intestines.

Congenital Congenital Chorioretinitis 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

• One of the most common noncardiac-related chest abnormalities found in the neonate Neonate An infant during the first 28 days after birth. Physical Examination of the Newborn
• 2 subtypes:
  • Bochdalek: most common, usually found in the posterolateral left chest
  • Morgagni: less common, usually found in the anterior chest
• Diaphragmatic defect will be seen on chest CT with abdominal components located in the chest
• Frequently associated with severe 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 of the ipsilateral lung ( aplasia Aplasia Cranial Nerve Palsies or hypoplasia Hypoplasia Hypoplastic Left Heart Syndrome (HLHS) of the ipsilateral lung is also possible)