In general, oral contrast is used for most abdominal and pelvic CT scans unless there is no suspicion of bowel pathology (e.g., noncontrast CT to detect kidney stones) or when administration. Imaging of Musculoskeletal Soft-Tissue Infections in Clinical Practice: A Comprehensive Updated Review. Specific imaging features exist that help identify the numerous forms of infection in the bones and soft tissues, and CT is invaluable for detecting deep complications of cellulitis and pinpointing the anatomic compartment that is involved by an infection. of 20 consecutive patients with necrotizing fasciitis, CT revealed fascial thickening and fat stranding in 80%, soft tissue gas in 55%, and abscesses in 35%.22, 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, MRI is the gold-standard for soft-tissue infections as it provides excellent soft-tissue contrast resolution with a sensitivity of 93% for the diagnosis for necrotizing fasciitis.1, 24 Essential sequences include T1 weighted imaging to assess anatomy, and T2 fat saturated or short tauinversion-recovery sequences to look for fascial thickening and edema.3, 25 Post gadolinium sequences are helpful to delineate the extent of infection, identify abscesses and areas of necrosis, but may not be feasible in patients with acute renal failure, which is common in this patient population.3, 26, Deep fascial thickening and subfascial fluid accumulation can be seen as high signal on fluid sensitive sequences (Figures 8 and 9).21 The deep intramuscular fascia is usually protected in the setting of cellulitis, but is involved in necrotizing fasciitis.1 Fascial thickening begins in the superficial fascia and extends along the deep intermuscular fascia, not just in areas contiguous to the deep peripheral fascia.1, 18 Hyperintensity and thickness of the fascia greater than or equal to 3 mm on fat saturated T2 weighted or short tauinversion-recovery images with involvement of three or more compartments is a sensitive finding to suggest necrotizing fasciitis.3, 8,13,25,27 The absence of T2 hyperintensity within the deep fascia can essentially exclude a diagnosis necrotizing fasciitis.3, 18,21. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. 2009;39(10):957-71. Preparation: Please have only a clear liquid diet for 4 hours prior to exam. 2. Careers, Unable to load your collection due to an error. 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. A person viewing it online may make one printout of the material and may use that printout only for his or her personal, non-commercial reference. Emerg Radiol. All Rights Reserved. Before What is the rationale for the laboratory workup for suspected pheochromocytomas and paragangliomas? Fasciae of the Musculoskeletal System: MRI Findings in Trauma, Infection and Neoplastic Diseases. No mutagenic or teratogenic effects have been shown with nonionic, low-osmolality contrast in animal studies. Given that metformin is excreted through the kidneys, IV contrast may impair metformin clearance from the body putting the patient at risk for metabolic acidosis. This site needs JavaScript to work properly. Cellulitis treatment usually includes a prescription oral antibiotic. 8. Pitfalls of CT for deep neck abscess imaging assessment: a T2 weighted image with fat saturation of the left thigh demonstrates a large area of myonecrosis within the proximal rectus femoris muscle, with extensive muscular, fascial, and subcutaneous enhancement and edema, with crescentic fascial fluid collections, predominantly around the rectus femoris and sartorius, suggestive of necrotizing fasciitis. Cellulitis (rare plural: cellulitides) is an acute infection of the dermis and subcutaneous tissues without deep fascial or muscular involvement. CT area of interest without IV contrast Usually Appropriate Varies Variant 7: Suspected soft tissue infection. 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. It is important to tell the technician and your doctor if you have had a previous allergic reaction to iodinated contrast. Inflammatory cellulitis is frequently confused with infectious cellulitis. Imaging of Musculoskeletal Soft Tissue Infections. endobj Possible reactions are listed in Table 1.7 If a patient has had a previous minor reaction to an IV iodinated contrast agent, precontrast administration of oral or IV corticosteroids and diphenhydramine (Benadryl) may decrease their risk (Table 27 ). Cross-sectional imaging findings include asymmetric thickening of the fascia, soft-tissue air, blurring of fascial planes, inflammatory fat stranding, reactive lymphadenopathy, and nonenhancement of the muscular fascia. endobj Unauthorized use of these marks is strictly prohibited. 8. Epub 2017 Mar 30. Within three days of starting an antibiotic, let your health care provider know whether the infection is responding to treatment. Contrast materials are generally safe; however, as with any pharmaceutical, there is the potential for adverse reactions. The most common contrast agents used with CT imaging are barium- and iodine-based. Some centers use oral contrast to evaluate for appendicitis; some do not use bowel contrast,3 and others use rectal contrast to avoid the delay associated with oral administration.4, Iodine-based intravenous (IV) contrast agents are used for opacification of vascular structures and solid abdominal and pelvic organs. DOI: https://doi.org/10.3949/ccjm.83a.15037, Computed tomography: revolutionizing the practice of medicine for 40 years, ACR-SCBT-MR-SPR practice parameter for the performance of thoracic computed tomography (CT), Screening for lung cancer: US Preventive Services Task Force recommendation statement, Solitary pulmonary nodules: dynamic enhanced multi-detector row CT study and comparison with vascular endothelial growth factor and microvessel density, High-pitch ECG-synchronized pulmonary CT angiography versus standard CT pulmonary angiography: a prospective randomized study, Intravenous contrast medium administration and scan timing at CT: considerations and approaches, Emergency imaging assessment of acute, nontraumatic conditions of the head and neck, Iodinated contrast media and their adverse reactions, ACR Committee on Drugs and Contrast Media, ACR Manual on Contrast Media. Water-soluble, iodine-based contrast agents can also be given orally. The specific agent and route of administration are based on clinical indications and patient factors. Detailed protocols for premedication and management of contrast adverse reactions are beyond the scope of this review and the reader is advised to refer to dedicated manuals.10. At the time the article was last revised David Carroll had Citation, DOI, disclosures and article data. PDF CT Ordering Guidelines - Baystate Health Diffuse high signal can also be seen in the muscle and subcutaneous fat.13 If subcutaneous edema is not the predominant feature, one should consider necrotizing fasciitis rather than cellulitis.1, 13 A summary of spectrum of findings for necrotizing fasciitis is summarized in Figure 10 and Table 2. Preparation: Please have only a clear liquid diet for 4 hours prior to exam. 2021;50(12):2319-47. Kirchgesner T, Tamigneaux C, Acid S et al. The site is secure. In patients with normal renal function, repeat measurement of serum creatinine is not recommended after outpatient administration of IV contrast agents.7. Even in osseous infection, CT and MRI can give better anatomic delineation of the extent of infection. 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. Soft-tissue gas is seen at the lateral aspect of the left knee along the fascial planes on the radiograph. Although many radiology departments screen for shellfish allergy, there is no cross-reactivity between shellfish and iodinated contrast. An official website of the United States government. MRI Nomenclature for Musculoskeletal Infection. Mediastinitis may likewise be iatrogenic or may spread from the oropharynx. In C, the transplanted lung is notable for areas of air trapping in the right upper lobe on expiratory images (blue arrow), which is associated with central airway narrowing. Bethesda, MD 20894, Web Policies www.acr.org/~/media/ACR/Documents/PGTS/guidelines/CT_Thoracic.pdf, www.acr.org/~/media/37D84428BF1D4E1B9A3A2918DA9E27A3.pdf, EVALUATION OF PULMONARY PARENCHYMAL DISEASE, EVALUATION OF STERNAL AND MEDIASTINAL INFECTIONS, Cleveland Clinic Center for Continuing Education. Even in osseous infection, CT and MRI can give better anatomic delineation of the extent of infection. If a diagnosis of orbital cellulitis is made, the patient needs to be immediately assessed monitored for signs of compartment syndrome and optic neuropathy which would warrant an . The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score: a tool for distinguishing necrotizing fasciitis from other soft tissue infections. myriad of non-infective erythematous rashes, Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. In particular, the evaluation of soft tissue infections, including cellulitus, myositis, fasciitis, abscess, and septic arthritis are often best evaluated by MRI or CT due to their excellent anatomic resolution and soft tissue contrast. Fascial thickening and involvement of multiple compartments is a sensitive finding on MRI. Turecki M, Taljanovic M, Stubbs A et al. Large volume of gas seen within the scrotum wall and scrotum sac on the scout image (curved black arrow), consistent with Fourniers gangrene. and transmitted securely. Rahmouni A, Chosidow O, Mathieu D et al. Check for errors and try again. Unable to process the form. References. Orbital cellulitis is an infectious process affecting the muscles and fat within the orbit, posterior or deep to the orbital septum, not involving the globe. Thank you for your interest in spreading the word on Cleveland Clinic Journal of Medicine. Ultrasound is usually the first investigation to evaluate a clinical suspicion of cellulitis. We are grateful for the editorial assistance of Megan M. Griffiths, scientific writer for the Imaging Institute, Cleveland Clinic. Contrast is not used in patients with head, extremity or spine trauma. Of the 26 orbits assessed by both CT and rMRI, three were positive for retroseptal orbital cellulitis by CT and were correctly diagnosed by rMRI as . Almost always, CTs should be ordered with or without contrast, not both. Shortness of breath Abdomen andPelvis Without IV contrast 1. Cross-sectional imaging findings include asymmetric thickening of fascia, soft tissue air, blurring of fascial planes, inflammatory fat stranding, reactive lymphadenopathy, and nonenhancement of muscular fascia. The location and extent of the inflammatory process was accurately demonstrated with axial CT scans in all cases. Contrast may also be avoided when the suspected pathology is likely to be visible on noncontrast-enhanced CT. A history should be obtained to determine if the reaction was mild (which typically requires observation but not treatment), moderate (which requires prompt treatment), or severe (which requires rapid intervention and, often, hospitalization). In uncomplicated cellulitis, CT demonstrates skin thickening, septation of the subcutaneous fat, and thickening of the underlying superficial fascia. CT with contrast can help to depict infection of the chest wall or mediastinum and in some instances can also delineate the route of spread.7, Contrast media used in CT contain iodine, which causes increased absorption and scattering of radiation in body tissues and blood. CT and MR imaging of orbital inflammation - PMC - National Center for Yen ZS, Wang HP, Ma HM, Chen SC, Chen WJ. A baseline serum creatinine level should be obtained up to one month before administration of intravenous contrast agents in patients with suspected renal insufficiency. If the infection spreads to deeper tissues, soft-tissue abscess, infectious myositis, necrotizing fasciitis, and osteomyelitis can all be detected with CT. MRI is sensitive for distinguishing cellulitis alone from necrotizing fasciitis and infectious myositis and for showing subcutaneous fluid collections and abscesses. Many practices have their own protocols for IV dye administration in patients using metformin so nurse practitioners must familiarize themselves with these policies. It results in pain, erythema, oedema, and warmth. Department of Radiology Department of Radiology Outpatients requiring oral contrast for a CT scan require a prescription for Readi-Cat 2, 2 bottles of 450ml, take as directed. N.p. There is no direct interaction between metformin and IV radiologic contrast agents. The .gov means its official. The U.S. Food and Drug Administration advises that metformin should be withheld at the time of IV contrast administration and for 48 hours afterward, and resumed only after reevaluation of renal status (i.e., return to baseline serum creatinine level).13. Schmid M, Kossmann T, Duewell S. Differentiation of Necrotizing Fasciitis and Cellulitis Using MR Imaging. Fortunately, orbital fat provides intrinsic background contrast, and most orbital pathologies can be easily visualised without infusion of a contrast medium. Special consideration should be given to geriatric patients, in whom cellulitis of the lower extremities is more likely to develop into thrombophlebitis. A 47-year-old male with necrotizing fasciitis of the left thigh. Bakleh M, Wold LE, Mandrekar JN, Harmsen WS, Dimashkieh HH, Baddour LM. Symptoms typically disappear a few . Unable to process the form. Diffuse thickening of the superficial fascia, which can be seen in the early phase of necrotizing fasciitis (c). BMJ. Reinert CP, Pfannenberg C, Dittmann H, Gckel B, la Fougre C, Nikolaou K, Hoefert S. J Clin Med. In the false-positive group, cellulitis was the most . Peri-orbital and orbital cellulitis - BMJ Best Practice Lactic acidosis has never been documented in patients with normal renal function who are receiving metformin. Muscular fascia lies deep to the subcutaneous layer. The diagnostic algorithm for lung cancer screening is evolving. In particular, the evaluation of soft tissue infections, including cellulitus, myositis, fasciitis, abscess, and septic arthritis are often best evaluated by MRI or CT due to their excellent anatomic resolution and soft tissue contrast. Contrast enhancement of the fascia can be variable depending on the stage of necrosis.1, 13,25 Enhancement of the affected fascia is thought to represent extravasated contrast from increased capillary permeability.
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