Rectal contrast can be used in patients with a suspected penetrating colonic injury.2 Rectal contrast does not always reach the cecum, so the small bowel and appendix can remain unopacified. Contrast-enhanced CT demonstrates air (arrows) and edema in the scrotum, surrounding the right testicle (a). Your email address will not be published. 1 0 obj Reinert CP, Pfannenberg C, Dittmann H, Gckel B, la Fougre C, Nikolaou K, Hoefert S. J Clin Med. Become a Gold Supporter and see no third-party ads. The most common contrast agents used with CT imaging are barium- and iodine-based. The choice of contrast agent depends on route of administration, desired tissue differentiation, and suspected diagnosis. Below is an overview of the following CTA studies and their indications: Regardless of the pathology youre looking for, contrast isnt right for everyone. 9. High-resolution CT, which is used to evaluate diffuse lung disease, does not use IV contrast.17 Noncontrast imaging of the abdomen is routinely done to screen for renal stones in patients with flank pain.18 Common clinical scenarios in which noncontrast-enhanced CT is appropriate are summarized in Table 4,19 and common clinical scenarios in which contrast enhancement is recommended are summarized in Table 5.19 Indications for selection of imaging studies for specific clinical scenarios can be searched using the American College of Radiology Appropriateness Criteria at http://www.acr.org/ac.19. 1. CT Exams Contrast vs Non-Contrast Guide These suggestions are general guidelines that apply to the use of contrast for CT exams provided at Oregon Imaging Centers. Muscular fascia lies deep to the subcutaneous layer. no financial relationships to ineligible companies to disclose. Normally the subcutaneous tissue is hypoechoic with few hyperechoic strands (representing connective tissue). Kim KT, Kim YJ, Won Lee J, Kim YJ, Park SW, Lim MK, et al.. Can necrotizing infectious fasciitis be differentiated from nonnecrotizing infectious fasciitis with MR imaging? CT is helpful in guiding surgical debridement and drainage by evaluating the extent of soft tissue and osseous involvement, identifying the potential infectious source and identifying potential complications including vascular rupture or tissue necrosis.1, 2,13,22 MAGNETIC RESONANCE IMAGING Uncomplicated cellulitis is usually treated conservatively with antibiotics and locally supportive measures. Compared to plain radiography, ultrasound, CT and MR provide higher sensitivity and specificity for the diagnosis of necrotizing fasciitis. Epidemiology Risk factors trauma foreign bodies ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. Please enable it to take advantage of the complete set of features! <>stream 9. 2 0 obj T2 weighted images with fat saturation demonstrates extensive high signal within the intermuscular septa surrounding the gastrocnemius and soleus muscle bellies suggestive of subfascial fluid (white arrows). Fasciae of the Musculoskeletal System: MRI Findings in Trauma, Infection and Neoplastic Diseases. Here is a summary of the indications for non-contrasted CT: Contrast helps enhance certain body structures. Axial CT with contrast enhancement obtained subsequently (B and C) shows that this abnormality corresponds to right hilar lymphadenopathy partially encasing the right pulmonary artery (arrows). Metformin should be held for 48 hours after the administration of IV contrast, and resumed only after serum creatinine returns to baseline levels, according to the U.S. Food and Drug Administration. Patients with peripheral vascular disease or diabetes mellitusare particularly susceptible to cellulitis since minor injuries to the skin or cracked skin in the feet or toes can serve as a point of entry for infection. Infect Dis Clin North Am. This absorption and scattering in turn results in higher CT attenuation values, or enhancement on CT images. Most centers use nonionic contrast agents (which are generally low osmolality) for IV contrast studies.5 The rate of major reactions (e.g., anaphylaxis, death) is the same for ionic and nonionic IV contrast agentsan estimated one in 170,000 administrationsbut nonionic contrast has a lower rate of minor reactions.6 Approximately 5% to 12% of patients who receive high-osmolality contrast have adverse reactions, most of which are mild or moderate.7 Use of low-osmolality contrast has been associated with a reduction in adverse effects. Epub 2017 Mar 30. Despite its limitations, radiographs can be more sensitive than physical exam for the detection of soft-tissue gas, with radiographic findings present before clinical crepitus is detected.17 Radiographs can also be helpful in identifying other causes of infection including the presence of a foreign body or underlying fracture.3, 13, The role of ultrasound is limited in the work-up of necrotizing fasciitis given that the lack of resolution of deeper structures.8 The presence of soft-tissue gas can be more apparent on ultrasound compared to radiographs.17, 18 Findings include an echogenic layer of gas above the deep fascia with posterior dirty acoustic shadowing (Figure 4).19 Other nonspecific findings include hyperechogenicity of the overlying fat, with cobblestone appearance indicating subcutaneous edema, but these findings can also be seen in cellulitis or anasarca.8, 19 Color Doppler evaluation may not reveal hypervascularity.8 Specific signs that are helpful to differentiate necrotizing fasciitis from cellulitis include irregularity of the fascia, abnormal fluid collection along fascial planes, and diffuse fascia thickening when compared to the contralateral unaffected side.8. Cellulitis. Cellulitis | Radiology Reference Article | Radiopaedia.org If the infection spreads to deeper tissues, complications can occur, such as soft-tissue abscess,necrotizing fasciitis,infectious myositis, and/or osteomyelitis. Clinical presentations include skin erythema without a well-defined border, increased skin temperature, swelling of the affected area, and regional lymphadenopathy and lymphangitis. sharing sensitive information, make sure youre on a federal 2019;10(1):47. The concentration of barium used for fluoroscopy is more than 20 times that of the typical oral contrast suspension for CT. For example, the barium concentration from an upper gastrointestinal series or an enema will produce an artifact on abdominal CT because it is significantly more concentrated than bowel contrast agents used for CT. Barium enemas are also given after abdominal CT to allow time for the less-dense barium to leave the colon. Intrathecal iodinated contrast is given during myelography to evaluate spinal or basal cisternal disease and cerebrospinal fluid leaks.11 Plain radiography of the spine is then obtained under fluoroscopic guidance. thickening of skin and superficial fascia, diffuse subcutaneous linear/reticular or ill-defined hyperintensity tending to collect at the hypodermis, contrast enhancement differentiates cellulitis from stasis oedema, areas of necrotising cellulitis do not enhance, degree of enhancement depends on the post contrast delay. Kirchgesner T, Tamigneaux C, Acid S et al. Fundic gland polyps: Should my patient stop taking PPIs? A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, organs, and blood vessels. We do not capture any email address. Cellulitis. the contents by NLM or the National Institutes of Health. Disclaimer. 2009;16(4):267-76. One study showed similar increases in serum creatinine levels between inpatient populations who received IV iodinated contrast and those who did not.16, Noncontrast-enhanced CT is used in patients with head trauma and acute stroke. Other contrast media, such as those used for magnetic resonance imaging or barium enemas, do not contain iodine.
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