Iodinated contrast should be avoided for two months before administration of iodine 131. 7. 9. 3. Possible contraindications for using intravenous contrast agents during computed tomography include a history of reactions to contrast agents, pregnancy, radioactive iodine treatment for thyroid disease, metformin use, and chronic or acutely worsening renal disease. 8600 Rockville Pike 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. Careers, Unable to load your collection due to an error. No mutagenic or teratogenic effects have been shown with nonionic, low-osmolality contrast in animal studies. 2021 Feb 1;94(1118):20200648. doi: 10.1259/bjr.20200648. In the false-positive group, cellulitis was the most . 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. Required fields are marked *. 2020;368:m710. 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 ). A 35-year-old male with necrotizing fasciitis of the right calf. During the injection you may feel flushed and get a metallic taste in your mouth. 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. Almost always, CTs should be ordered with or without contrast, not both. Infect Dis Clin North Am. Careers. Kidney/ureteral stones With IV contrast 1. Emerg Radiol. Check for errors and try again. Copyright 2016 The Cleveland Clinic Foundation. 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. 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). A 64-year-old male with Fourniers gangrene with perforated diverticulitis. 2009;39(10):957-71. Adams, James, and Erik D. Barton. The choice of contrast agent depends on route of administration, desired tissue differentiation, and suspected diagnosis. 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. If the infection spreads to deeper tissues, soft-tissue abscess, infectious myositis, necrotising fasciitis, and osteomyelitis can all be detected with CT. MRI is sensitive for distinguishing cellulitis alone from necrotising fasciitis and infectious myositis and for showing subcutaneous fluid collections and abscesses. Skeletal Radiol. 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. Thank you for your interest in spreading the word on Cleveland Clinic Journal of Medicine. Contrast-enhanced CT demonstrates crescentic subfascial fluid (arrow) with fluid also seen superficial to the fascia (arrow head) and between muscle planes (a). One of these questions that came up frequently related to CT scans was Do I need contrast?. Mitchell C, Dolan N, Drsteler K. Management of Dependent Use of Illicit Opioids. Yes neuro CTa HeaD Circle of Willis CTA Head with and without contrast Note: MRA Brain without contrast is preferred. However, IV radiologic contrast may cause transient alteration in renal function, which could impair metformin clearance, leading to a higher risk of metabolic acidosis. Hydration can decrease these risks. This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. It results in pain, erythema, edema, and warmth. 07/16 RH /MF myriad of non-infective erythematous rashes, Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Inflammatory cellulitis is frequently confused with infectious cellulitis. government site. Alaia E, Chhabra A, Simpfendorfer C et al. It is usually due to underlying bacterial sinusitis. 2022 Mar 5;87:e141-e162. Cellulitis can affect any region of the body, and commonly affects a lower limb. 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. Accessibility 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. The extent of enhancement depends on the amount and rate of contrast material administered, as well as on patient factors (eg, tissue vascularity, permeability, interstitial space) and the energy (tube voltage) of the incident x-rays.8. government site. If youre a nurse practitioner who struggles with the same question, check out the following guide to contrast and CT scans. Contrast: A plain ct looks for stones. 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. Peri-orbital cellulitis is of concern in children because it may be secondary to occult underlying bacterial sinusitis or, rarely, due . 2 0 obj Emerg Radiol. A 45-year-old male with necrotizing fasciitis of the right thigh. Oral contrast agents are barium- or iodine-based and are used for bowel opacification. 2007 Nov-Dec;27(6):1723-36. doi: 10.1148/rg.276075033. Cellulitis can affect any region of the body, and commonly affects a lower limb. 4 0 obj Bakleh M, Wold LE, Mandrekar JN, Harmsen WS, Dimashkieh HH, Baddour LM. The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score: a tool for distinguishing necrotizing fasciitis from other soft tissue infections. There are several contrast agents that may be used in performing CT scans. Contrast-related nephrotoxicity has been reported,11 although this has been challenged more recently.12 Suspected risk factors for this complication include advanced age, cardiovascular disease, treatment with chemotherapy, elevated serum creatinine level, dehydration, diabetes, use of nonsteroidal anti-inflammatory medications, myeloma,13 renal disease, and kidney transplant. In the emergency setting, CT of the neck is often performed to investigate symptoms of acute infection or inflammation or symptoms of aerodigestive tract compromise referable to the neck. 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. 1998;170(3):615-20. The most common are baruim and iodine based. Musculoskeletal infection: role of CT in the emergency department. Iodinated contrast crosses the human placenta. sonographic hallmarks of cellulitis include abnormal echogenicity and increased thickness of the dermis with indistinct "haziness" and increased echogenicity of the subcutaneous tissue, it is often helpful to compare the area in question to the (presumably normal)contralateral side, progressive accumulation of edema in the subcutaneous tissue appears as branching, anechoic striations which impart a lobulated ("cobble-stone" appearance), presence of thickened and abnormally echogenic overlying skin will favor cellulitis over edema, linear anechoic bands of fluid deep to the subcutaneous layer favor lymphedema, ultrasound is more sensitive than MRI for the detection of a retained foreign body as the causative agent, especially if small and wooden 4,5. Compared to plain radiography, ultrasound, CT and MR provide higher sensitivity and specificity for the diagnosis of necrotizing fasciitis. 3. FOIA Different imaging modalities require different concentrations of contrast for optimal detection of pathology. However, patients with a documented anaphylactic reaction to any medication are at higher risk of a reaction to iodinated contrast.9,10, Many centers screen outpatients with suspected renal insufficiency by measuring serum creatinine one month before administration of contrast agents. Miller TT, Randolph DA, Staron RB, Feldman F, Cushin S. Fat-suppressed MRI of musculoskeletal infection: fast T2-weighted techniques versus gadolinium-enhanced T1-weighted images, Necrotizing fasciitis: unreliable MRI findings in the preoperative diagnosis, Differentiation of necrotizing fasciitis and cellulitis using MR imaging. dobrien Sagittal CT reformation demonstrates linear fluid collection (arrow) deep to the rectus femoris muscle (b). In patients with elevated creatinine, withholding IV dye may be necessary. CT is used to accurately differentiate between superficial cellulitis and deep cellulitis. Radiol Clin North Am. In patients with normal renal function, repeat measurement of serum creatinine is not recommended after outpatient administration of IV contrast agents.7. The site is secure. There is no direct interaction between metformin and IV radiologic contrast agents. Oral contrast can be administered through a nasogastric tube to minimize the risk of aspiration. When the neoplasm has CT attenuation similar to that of adjacent structures (lymph nodes in the hilum, masses in the mediasti-num or chest wall), IV contrast can improve identification of the lesion and delineation of its margins and the relationship with adjacent structures (eg, vascular structures) (Figure 1). The American College of Radiology proposes a three-tiered risk assessment for patients receiving metformin in whom IV contrast is to be administered (Table 3).7 Many institutions have their own protocols for metformin administration with IV contrast, so physicians should be aware of the standard of care in their community. Working in the emergency department as a nurse practitioner, I order CT scans in my evaluation of patients every day. Enter multiple addresses on separate lines or separate them with commas. . A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, organs, and blood vessels. 2022 Nov 25;10(12):2329. doi: 10.3390/microorganisms10122329. MRI Nomenclature for Musculoskeletal Infection. Patients with a mild allergy may be pre-medicated with an antihistamine or steroids before imaging. 2020;368:m710. 6. Maximum-intensity projection images reconstructed in the axial (A) and coronal (B) planes show bilateral arteriovenous malformations with corresponding feeding arteries (white arrows) and draining veins (black arrows). CT without contrast in a patient with a history of interstitial lung disease and right lung transplant shows the patent but partially narrowed anastomotic site of the right bronchus (A) (red arrow). Soft-tissue gas is a specific finding on all modalities, but is not present in all patients with necrotizing fasciitis. Fundic gland polyps: Should my patient stop taking PPIs? Magn Reson Imaging Clin N Am. The purpose of this article is to review the imaging findings of necrotizing fasciitis as seen on radiograph, ultrasound, CT, and MRI, and to recognize the early findings in this potentially fatal disease. In a 79-year-old patient with chronic thromboembolic pulmonary hypertension, CT angiography of the pulmonary artery (A) shows weblike (red arrow) and partially calcified filling defects (yellow arrow), as well as diffuse mild mosaic attenuation of lung parenchyma (B). In cases of suspected arteriovenous malformation, a protocol similar to that used for suspected pulmonary embolus is used (Figure 3), although in some instances, the imaging features of arteriovenous malformation may be detectable without IV contrast. In patients with normal renal function, repeat measurement of serum creatinine is not recommended after outpatient administration of intravenous contrast agents. Other contrast media, such as those used for magnetic resonance imaging or barium enemas, do not contain iodine. It is injected through an intravenous line during the examination. The CT and MRI findings in the spectrum of musculoskeletal infections are discussed and contrasted, and pitfalls in their evaluation of musculoskeletal infection are described. What is the rationale for the laboratory workup for suspected pheochromocytomas and paragangliomas? All Rights Reserved. The specific agent and route of administration are based on clinical indications and patient factors. Unauthorized use of these marks is strictly prohibited. CT without contrast in a patient with a history of interstitial lung disease and right lung trans-plant shows the patent but partially narrowed anastomotic site of the right bronchus (A) (red arrow). While the plain film and nuclear medicine bone scan are still the traditional imaging modalities used in the evaluation of musculoskeletal infection, the cross-sectional imaging modalities, computed tomography (CT) and magnetic resonance imaging (MRI), have become critical in the delineation of many types of musculoskeletal infection.

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