Computed Tomography (CT)

Computed tomography (CT) is one of the most commonly used imaging methods because it is widely available, fast, and reliable. CT scans deploy X-rays X-rays X-rays are high-energy particles of electromagnetic radiation used in the medical field for the generation of anatomical images. X-rays are projected through the body of a patient and onto a film, and this technique is called conventional or projectional radiography. X-rays to obtain cross-sectional images of the body. A CT scanner consists of a tube that rotates around the patient and emits an X-ray beam and a detector that uses specialized software to receive and convert the beam to an image. The ability to create multiple views (axial, sagittal, coronal) and use contrast (intravenous, oral, rectal) allows for enhanced diagnostic yield. Patients are exposed to radiation, and special consideration should be given to patients with a history of iodine allergy, renal disease, or thyroid disease or patients who are pregnant.

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Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

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Terminology and Technology

General component

  • Rotating X-ray tube: 
    • Spins around the patient
    • High-energy electrodes Electrodes Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum. Normal Electrocardiogram (ECG) in the tube emit radiation beams. 
    • Radiation passes through the patient’s body.
  • Radiation detectors: 
    • On the opposite side of the patient’s body from the X-ray tube
    • Absorbs and measures the remaining radiation (in the form of varying density) after it has passed through tissues
    • Computer software detects the tomography generated by the detector and reconstructs an image.
  • Motorized table: advances the patient through the scanner
Ct device components

CT scan components:
Arrangement of the X-ray tube and detectors in the CT scanner

Image by Lecturio.

Types of CT scanners

Helical (“spiral”):

  • Most common due to its speed
  • As the patient is moved through the CT, the rotating beam and X-ray detector spin. This creates a helical path.
  • Results in a 3-dimensional data set
  • Minimizes errors due to patient movement or breathing

Sequential (step-and-shoot):

  • Was the conventional method before helical CT
  • The patient is moved through the CT with short pauses to capture images at each position.
  • Results in an ↑ radiation dose
  • Used for high-resolution scanning 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 and 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 and for coronary CT angiography
Helical vs sequential ct

Differences between sequential and helical CT scanners:
Sequential CT takes discrete imaging slices as the patient moves through the scanner, whereas the continuous movement of the helical CT results in a spiral path.

Image by Lecturio.

Image processing

Digital images are created with a matrix of voxels (3-dimensional pixels), which are measured in Hounsfield units (HU).

  • An index used to universally quantify the radiodensity of imaged findings on CT
  • Based on the amount of radiation that a material absorbs:
    • Dense material will appear bright.
    • Less dense material will appear dark.
  • The index is constructed on assigned values to water (0 HU) and air (–1000 HU).

Postprocessing can be used to accentuate tissues of different densities.

  • Lung window
  • 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. Structure of Bones window
  • Soft tissue window

Images can also be produced in different viewing planes.

  • Axial (looking from the feet up to the head)
  • Sagittal (looking from the side)
  • Coronal (looking from the front)
Table: Density of different material images on CT
Substance Hounsfield units (HU)
Air –1000 The darkest (most hypodense)












The brightest (most hyperdense)
Fat –100 to –50
Water 0
Soft tissue 20–300
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. Structure of Bones 250‒700
This table shows the density of different materials that would be imaged on CT. As you can see, materials with a higher density than water will have a positive value (and are brighter), while negative values are assigned to those with lower densities (and are darker).
Ct image planes

CT image viewing planes:
The slices through this model demonstrate how axial, coronal, and sagittal images correlate with the patient’s anatomy.

Image by Lecturio.

Contrast enhancement

Contrast

Contrast agents may be used to enhance visualization of targeted tissues.

  • Oral:
    • Used for defining the bowel on abdominal and pelvic CT scans
    • Agents: 
      • Barium sulfate (most common)
      • Isovue (an iodine-based solution)
      • Gastrografin (water-soluble, used to evaluate for bowel perforation)
    • Does not affect the kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys
  • IV:
    • Used for enhancement and differentiation of vascular structures and solid organs
    • Agent: iodinated, low ionic, low osmolar solution
    • X-rays X-rays X-rays are high-energy particles of electromagnetic radiation used in the medical field for the generation of anatomical images. X-rays are projected through the body of a patient and onto a film, and this technique is called conventional or projectional radiography. X-rays are absorbed by the contrast → ↑ attenuation
      • Contrast becomes more dilute as it moves from the 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 → tissues → veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins
      • Image appearance changes over time. 
    • Enhancement is based on:
      • The amount of blood 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
      • Timing of the image after contrast administration
    • Excreted by kidneys Kidneys The kidneys are a pair of bean-shaped organs located retroperitoneally against the posterior wall of the abdomen on either side of the spine. As part of the urinary tract, the kidneys are responsible for blood filtration and excretion of water-soluble waste in the urine. Kidneys (should be used judiciously in acute or chronic renal failure)
  • Rectal:
    • Used for suspected penetrating colonic injury
    • Agents: 
      • Isovue
      • Gastrografin
    • Given as an enema

Phases

Multiphase CT can identify structures at various intervals after IV contrast administration.

  • Noncontrast phase: prior to contrast injection
  • Vascular (arterial) or bolus phase:
    • 15–20 seconds after injection
    • Contrast diffuses into the vasculature.
    • Opacifies the aorta and its branches
    • Allows differentiation of renal cortex and medulla
  • Redistribution (venous) phase:
    • 1–3 minutes after injection
    • Contrast diffuses from intravascular to extravascular compartment.
    • Opacifies the inferior vena cava Inferior vena cava The venous trunk which receives blood from the lower extremities and from the pelvic and abdominal organs. Mediastinum and Great Vessels, large veins Veins Veins are tubular collections of cells, which transport deoxygenated blood and waste from the capillary beds back to the heart. Veins are classified into 3 types: small veins/venules, medium veins, and large veins. Each type contains 3 primary layers: tunica intima, tunica media, and tunica adventitia. Veins, and solid organ parenchyma
  • Equilibrium (delayed) phase:
    • 6–10 minutes after injection
    • Contrast reaches dynamic equilibrium in the intravascular and extravascular compartments.
    • Opacifies the renal collecting system, ureters, and urinary bladder
Hepatic alveolar echinococcosis imaging

Axial multiphase CT images of the abdomen:
a: Unenhanced image shows an infiltrative tumor-like hepatic mass.
b: Postcontrast arterial phase shows a nonenhancing, hypoattenuating lesion.
c: Postcontrast portal-venous phase shows a faint enhancement of fibroinflammatory components surrounding the parasitic pseudocyst.

Image: “Hepatic alveolar echinococcosis Echinococcosis Echinococcosis is a parasitic disease caused by Echinococcus tapeworms. Infection most often occurs from the ingestion of Echinococcus eggs in food or water contaminated with dog feces. Signs and symptoms are caused by hydatid cyst development in visceral organs and depend on the species. Echinococcus/Echinococcosis imaging” by Wenya Liu et al. License: CC BY 4.0

Interpretation

The best approach is a systematic approach.

  • Check the patient’s demographics and name and the date.
  • Note the reason for the study.
  • Determine the part of the body that was imaged.
  • Look for prior imaging to allow for comparison.
  • Determine the image viewing plane and orientation.
  • Use multiple window levels and scroll through multiple times to ensure that all sections are covered. 
  • Viewing windows can be changed to optimize imaging of the desired organ system.
  • Evaluate one organ at a time.

Indications

Head CT

Noncontrast:

  • Severe head trauma Head trauma Head trauma occurs when external forces are directed to the skull and brain structures, resulting in damage to the skull, brain, and intracranial structures. Head injuries can be classified as open (penetrating) or closed (blunt), and primary (from the initial trauma) or secondary (indirect brain injury), and range from mild to severe and life-threatening. Head Trauma
  • Stroke
  • Intracranial bleeding (appears hyperdense when acute)

Contrast:

  • Enhances neoplasms and infections
  • The angiographic phase is used to look for: 
    • Large-vessel occlusion
    • Arteriovenous malformation
    • 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. Extremity and Visceral Aneurysms

Chest CT

  • Lung parenchymal diseases:
    • Interstitial lung disease
    • Pneumonia
    • Lung cavitations
    • Abscess
    • Lung cancer Lung cancer Lung cancer is the malignant transformation of lung tissue and the leading cause of cancer-related deaths. The majority of cases are associated with long-term smoking. The disease is generally classified histologically as either small cell lung cancer or non-small cell lung cancer. Symptoms include cough, dyspnea, weight loss, and chest discomfort. Lung Cancer
  • Chest trauma:
    • Rib fractures
    • Pulmonary contusion
    • Diaphragmatic rupture
    • Laceration of the aorta or great vessels
  • Pleural disease:
    • Loculated effusions
    • Empyema
    • 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
  • Mediastinal pathology:
    • Cardiac tumors
    • Pericardial effusion Pericardial effusion Pericardial effusion is the accumulation of excess fluid in the pericardial space around the heart. The pericardium does not easily expand; thus, rapid fluid accumulation leads to increased pressure around the heart. The increase in pressure restricts cardiac filling, resulting in decreased cardiac output and cardiac tamponade. Pericardial Effusion and Cardiac Tamponade
    • Pneumomediastinum
  • Vascular disease:
    • 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
    • Aortic aneurysm or dissection

Abdominal and pelvic CT

Evaluation for abdominal and pelvic pathology:

  • Blunt or penetrating abdominal injury Penetrating abdominal injury Penetrating abdominal injuries are created by an object puncturing the abdominal wall. Injuries can be high velocity, like gunshot wounds, or low velocity, like stab wounds. Different structures can be injured, including the duodenum, spleen, liver, kidneys, and pelvic organs. Penetrating Abdominal Injury
  • Appendicitis Appendicitis Appendicitis is the acute inflammation of the vermiform appendix and the most common abdominal surgical emergency globally. The condition has a lifetime risk of 8%. Characteristic features include periumbilical abdominal pain that migrates to the right lower quadrant, fever, anorexia, nausea, and vomiting. Appendicitis
  • Diverticulitis
  • Pancreatitis
  • Intra-abdominal infections
  • Renal, ureteral, and bladder calculi 
  • Pneumoperitoneum
  • Bowel obstruction
  • Aortic aneurysm and dissection
  • Retroperitoneal hemorrhage

Evaluation of visceral malignancies:

  • Characterization of abdominal and pelvic masses
  • Staging Staging Cancer is the 2nd leading cause of death in the US after cardiovascular disease. Many malignancies are treatable or curable, but some may recur. Thus, all malignancies must be assigned a grade and stage in order to guide management and determine prognosis. Grading, Staging, and Metastasis evaluation of known malignancy
  • Monitoring with treatment
Ct scan of middle abdomen showing a subcapsular hepatic hematoma

CT scan of the middle abdomen showing a subcapsular hepatic hematoma on the surface of the right lobe of the liver (hypodense area indicated by the arrows) with a source of active bleeding (circle)

Image: “CT scan of middle abdomen showing a subcapsular hepatic hematoma” by From the Department of General Surgery, C.S. General and Emergency Surgery, Azienda Ospedaliera – IRCCS Arcispedale Santa Maria Nuova, Reggio Emilia, Italy. License: CC BY 4.0

Special Considerations and Contradictions

Radiation exposure

Like other imaging methods, CT scans expose patients to radiation.

  • Ionizing radiation is additive.
  • Number of scans should be limited whenever possible.
  • Radiation dose:
    • Chest and abdominal CT: 10 mSv
    • Pelvic CT: 7 mSv
    • Head CT: 2 mSv
  • In context:
    • Chest X-ray: 0.013 mSv
    • Low risk of fetal malformation: < 50 mSv
    • Substantial fetal damage: > 500 mSv
  • Effects of radiation:
    • Molecular damage
    • Free radical formation
    • Disruption of cellular metabolic function
    • Cell death Cell death Injurious stimuli trigger the process of cellular adaptation, whereby cells respond to withstand the harmful changes in their environment. Overwhelmed adaptive mechanisms lead to cell injury. Mild stimuli produce reversible injury. If the stimulus is severe or persistent, injury becomes irreversible. Apoptosis is programmed cell death, a mechanism with both physiologic and pathologic effects. Cell Injury and Death after a certain threshold
    • Carcinogenic risk increases with exposure.

Contraindications

  • Allergic reactions to contrast agents:
    • May manifest as hives Hives Urticaria is raised, well-circumscribed areas (wheals) of edema (swelling) and erythema (redness) involving the dermis and epidermis with associated pruritus (itch). Urticaria is not a single disease but rather is a reaction pattern representing cutaneous mast cell degranulation. Urticaria (Hives) or anaphylaxis
    • Patients can be premedicated with steroids and antihistamines Antihistamines Antihistamines are drugs that target histamine receptors, particularly H1 and H2 receptors. H1 antagonists are competitive and reversible inhibitors of H1 receptors. First-generation antihistamines cross the blood-brain barrier and can cause sedation. Antihistamines if a contrast CT is necessary.
  • Pregnancy Pregnancy Pregnancy is the time period between fertilization of an oocyte and delivery of a fetus approximately 9 months later. The 1st sign of pregnancy is typically a missed menstrual period, after which, pregnancy should be confirmed clinically based on a positive β-HCG test (typically a qualitative urine test) and pelvic ultrasound. Pregnancy: Diagnosis, Maternal Physiology, and Routine Care: Iodinated contrast can cross the placenta Placenta The placenta consists of a fetal side and a maternal side, and it provides a vascular communication between the mother and the fetus. This communication allows the mother to provide nutrients to the fetus and allows for removal of waste products from fetal blood. Placenta, Umbilical Cord, and Amniotic Cavity.
  • Thyroid disease: 
    • Iodinated contrast will reduce uptake of radioactive iodine → treatment is less effective
    • Hyperthyroidism Hyperthyroidism Thyrotoxicosis refers to the classic physiologic manifestations of excess thyroid hormones and is not synonymous with hyperthyroidism, which is caused by sustained overproduction and release of T3 and/or T4. Graves' disease is the most common cause of primary hyperthyroidism, followed by toxic multinodular goiter and toxic adenoma. Thyrotoxicosis and Hyperthyroidism patients may develop thyroid storm from contrast.
  • Chronic or acutely worsening renal disease: Iodinated contrast can cause acute tubular necrosis.

Other Imaging Methods

Comparison of imaging methods

Table: Comparison of imaging methods
Radiography CT Ultrasound MRI
Mechanism of acquisition Ionizing radiation Ionizing radiation Acoustic energy Ferromagnetic pulses
Relative cost Inexpensive Expensive Inexpensive Very expensive
Portable Yes No Yes No
Length of exam Seconds < 1 minute Seconds Approximately 1 hour
Contrast No May be needed May be needed May be needed

Imaging method options by system

  • Imaging of the CNS (brain, 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, and vertebral column Vertebral column 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): 
    • Radiography is often used to evaluate for fractures of the vertebral column Vertebral column 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
    • CT is a good choice for head trauma Head trauma Head trauma occurs when external forces are directed to the skull and brain structures, resulting in damage to the skull, brain, and intracranial structures. Head injuries can be classified as open (penetrating) or closed (blunt), and primary (from the initial trauma) or secondary (indirect brain injury), and range from mild to severe and life-threatening. Head Trauma and to exclude intracranial hemorrhage. 
    • MRI provides more detailed images of the brain and 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, allowing identification of infarction, tumors, disc herniation, and demyelinating disease.
  • Pulmonary radiology Pulmonary Radiology Pulmonary, or chest, imaging includes imaging of the lungs 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, CT, MRI, and ultrasonography (US). Pulmonary Radiology and imaging 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
    • Radiography is the preferred initial imaging study for viewing lung pathology. 
    • CT scan provides more detailed views of the lung parenchyma, mediastinal structures, and vasculature. 
    • MRI is not often used, but may be employed for evaluating malignancies and cardiac disease. 
    • Ultrasonography can be used for a rapid bedside trauma assessment and for guiding procedures (thoracentesis).
  • Breast imaging Breast Imaging Female breasts, made of glandular, adipose, and connective tissue, are hormone-sensitive organs that undergo changes along with the menstrual cycle and during pregnancy. Breasts may be affected by various diseases, in which different imaging methods are important to arrive at the correct diagnosis and management. Mammography is used for breast cancer screening and diagnostic evaluation of various breast-related symptoms. Breast Imaging
    • Mammography is often the initial choice for breast cancer screening Breast cancer screening Breast cancer is the most common cancer in women and the 2nd-leading cause of cancer-related deaths in women in the United States. Early detection and improved pathology-specific treatments have resulted in a decrease in death rates. Breast Cancer Screening
    • MRI may be used to further evaluate and stage breast cancer Breast cancer Breast cancer is a disease characterized by malignant transformation of the epithelial cells of the breast. Breast cancer is the most common form of cancer and 2nd most common cause of cancer-related death among women. Breast Cancer
    • Ultrasonography is helpful for evaluating lymph nodes and to guide biopsy.
  • Imaging of the abdomen and renal imaging Renal imaging The renal system is composed of 2 kidneys, 2 ureters, a bladder, and a urethra. Varying conditions such as infections, cysts, solid masses, ischemia, and mechanical obstruction can affect the renal system. Evaluation of diseases rely on imaging methods such as radiography, ultrasonography, CT, and MRI. Some of these are also used to guide tissue sampling (e.g., renal biopsy). Renal Imaging
    • Radiography is often used to evaluate for kidney stones, bowel obstruction, and pneumoperitoneum. In addition, barium may be used to assess swallowing and bowel function. 
    • CT and MRI provide more detailed assessments of the abdominal viscera and vasculature. 
    • Nuclear medicine can be used to assess gallbladder Gallbladder The gallbladder is a pear-shaped sac, located directly beneath the liver, that sits on top of the superior part of the duodenum. The primary functions of the gallbladder include concentrating and storing up to 50 mL of bile. Gallbladder and Biliary Tract function and gastric emptying and for GI bleeding.
  • Imaging of the uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Posterior Abdominal Wall and ovaries Ovaries Ovaries are the paired gonads of the female reproductive system that contain haploid gametes known as oocytes. The ovaries are located intraperitoneally in the pelvis, just posterior to the broad ligament, and are connected to the pelvic sidewall and to the uterus by ligaments. These organs function to secrete hormones (estrogen and progesterone) and to produce the female germ cells (oocytes). Ovaries
    • Ultrasonography is the most commonly used method to evaluate the ovaries Ovaries Ovaries are the paired gonads of the female reproductive system that contain haploid gametes known as oocytes. The ovaries are located intraperitoneally in the pelvis, just posterior to the broad ligament, and are connected to the pelvic sidewall and to the uterus by ligaments. These organs function to secrete hormones (estrogen and progesterone) and to produce the female germ cells (oocytes). Ovaries and uterus Uterus The uterus, cervix, and fallopian tubes are part of the internal female reproductive system. The uterus has a thick wall made of smooth muscle (the myometrium) and an inner mucosal layer (the endometrium). The most inferior portion of the uterus is the cervix, which connects the uterine cavity to the vagina. Posterior Abdominal Wall, including assessing pregnancies and the causes of abnormal uterine bleeding Abnormal Uterine Bleeding Abnormal uterine bleeding is the medical term for abnormalities in the frequency, volume, duration, and regularity of the menstrual cycle. Abnormal uterine bleeding is classified using the acronym PALM-COEIN, with PALM representing the structural causes and COEIN indicating the non-structural causes. Abnormal Uterine Bleeding
    • CT and MRI provide more detailed views and are often useful in assessing cysts, malignancies, and benign masses.
  • Imaging of the musculoskeletal system: 
    • Radiography is often used to exclude fractures. 
    • CT is more sensitive to bone pathology, including osteomyelitis Osteomyelitis Osteomyelitis is an infection of the bone that results from the spread of microorganisms from the blood (hematogenous), nearby infected tissue, or open wounds (non-hematogenous). Infections are most commonly caused by Staphylococcus aureus. Osteomyelitis
    • MRI is preferred for a soft tissue evaluation, such as assessing for malignancy and myositis. 
    • 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. Structure of Bones scanning can be useful in finding occult fractures, osteomyelitis Osteomyelitis Osteomyelitis is an infection of the bone that results from the spread of microorganisms from the blood (hematogenous), nearby infected tissue, or open wounds (non-hematogenous). Infections are most commonly caused by Staphylococcus aureus. Osteomyelitis, and metabolic bone disease.

References

  1. Kocak, M. (2019). Computed tomography. MSD Manual Professional Version. Retrieved December 2, 2020, from https://www.msdmanuals.com/professional/special-subjects/principles-of-radiologic-imaging/computed-tomography
  2. Stark, P. (2020). Principles of computed tomography of the chest. In Finlay, G. (Ed.), UpToDate. Retrieved December 2, 2020, from https://www.uptodate.com/contents/principles-of-computed-tomography-of-the-chest
  3. Rawson, J. V., Pelletier, A. L. (2013). When to order a contrast-enhanced CT. American Family Physician 88(5):312–316.
  4. Knipe, H., and Nadrljanksi, M.M. (2019). Computed tomography. Radiopedia. Retrieved December 2, 2020, from https://radiopaedia.org/articles/computed-tomography
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