ct with or without contrast for cellulitis

IV dye may cause a temporary alteration in kidney function. 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. This question is for testing whether or not you are a human visitor and to prevent automated spam submissions. In pleural effusion, CT assessment for the presence, location, and extent of the effusion does not require contrast. No mutagenic or teratogenic effects have been shown with nonionic, low-osmolality contrast in animal studies. My answer is based on the current radiologic practices and terminology employed in the U.S. 1. Your email address will not be published. This is commonly ordered for diagnosis of: 1. A 47-year-old male with necrotizing fasciitis of the left thigh. % 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. In certain situations, however, a contrast medium is essential. 1998 Aug;6(3):537-59. For the assessment of vascular disease, CT in most cases requires IV contrast to delineate the vessel lumen. Sinus radiographs, which were also obtained, were not helpful in diagnosis or management. In a patient with colon cancer undergoing a workup for metastases, axial CT without contrast (A) shows prominence of the right hilar region (arrow). Radiographics. When I was newer to my role, I had a lot of questions about diagnostic imaging, when it was indicated, and what test to order. dobrien Mediastinitis may likewise be iatrogenic or may spread from the oropharynx. One of these questions that came up frequently related to CT scans was Do I need contrast?. Computed tomography (CT) plays an important role in the diagnosis and treatment of many clinical conditions1 involving the chest wall, mediastinum, pleura, pulmonary arteries, and lung parenchyma. Additionally, systemic features such as fevers and rigors may also be present. Assessment of interstitial lung disease does not require use of IV contrast; rather, a tailored protocol with thinner slices and non-contiguous expiratory images can be used to evaluate for air-trapping and dynamic airway compromise (Figure 4). Sagittal CT reformation demonstrates linear fluid collection (arrow) deep to the rectus femoris muscle (b). 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. HHS Vulnerability Disclosure, Help Hayeri MR, Ziai P, Shehata ML, Teytelboym OM, Huang BK. , Acuterecurrent rhinosinusitis Copyright 2023 The Cleveland Clinic Foundation. 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 . No circumscribed collection, or signs of bulbar or intraconal involvement (note the preservation of the normal intraorbital fat density). endstream Additionally, systemic features such as fevers and rigors may also be present. 4 0 obj Alaia E, Chhabra A, Simpfendorfer C et al. . Cellulitis treatment usually includes a prescription oral antibiotic. 2009;39(10):957-71. Cross-sectional schematic diagram through the right thigh demonstrating the various findings of necrotizing fasciitis. In cases where the plain film and nuclear medicine bone scan findings are complicated due to previous surgery, trauma, or underlying illness, the anatomic resolution and soft tissue contrast provided by MRI and CT are often necessary to determine if underlying infection exists. Diagnosing Pediatric Orbital Cellulitis: CT or rMRI? 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. Clinical findings suggestive of necrotizing fasciitis vs cellulitis.7, There have been association with intravenous drug use as well as chronic conditions including diabetes mellitus, immunosuppression, obesity, and peripheral vascular disease.3, 8 A history of recent surgery (within the past 90 days) at the affected site has been shown to be a strong predictor for necrotizing fasciitis.7, Infection typically begins in the superficial fascial planes, then rapidly progress into the deep fascial layers, which causes necrosis secondary to microvascular occlusion.1 The rate of spread of infection is directly proportional to the thickness of the subcutaneous layers, with fastest spread seen in the lower extremities due to the lack of fibrous boundaries between subcutaneous tissue and fascia.2, 9, Necrotizing fasciitis is a clinical diagnosis since imaging findings can be nonspecific or unremarkable early in the course of the disease.1 The majority of cases are initially misdiagnosed, causing delay in diagnosis.10 Imaging appearances of necrotizing fasciitis can also overlap with other conditions, including nonnecrotizing fasciitis, dermatomyositis, graft vs host disease, or ischemic myonecrosis.1 The main utility of imaging is to determine the extent of the soft-tissue infection as well as to guide surgical planning.1, 8 If the patient is presenting with shock, imaging should not delay the initiation of treatment.1 Definitive diagnosis is based on surgical exploration and biopsy and aggressive surgical fasciotomy of necrotic tissue is required to prevent the spread of infection.7, Early findings of necrotizing fasciitis on radiography can appear similar to cellulitis including soft-tissue opacity and thickening.1113 The classical findings of dissecting gas along fascial planes in the absence of trauma is a specific sign, but is only seen in 24.855.0% of patients, and may not be seen until late in the disease (Figures 1 and 2).1, 10,12 Necrotizing fasciitis commonly affects the lower extremities, with involvement of the perineum or scrotum, classically known as Fourniers gangrene (Figure 3).3, 14,15 Soft-tissue gas is typically caused by gas-forming anaerobic infections, although this may not be present in diabetic patients.16 As such, the absence of soft-tissue emphysema does not exclude a diagnosis of necrotizing fasciitis.1. Accessibility Negative studies or nonspecific findings in the context of high clinical suspicion for necrotizing fasciitis, should be treated promptly as this is a clinical diagnosis. The most common are baruim and iodine based. CT Scans: When Do You Need Contrast? | ThriveAP Alaia E, Chhabra A, Simpfendorfer C et al. Here is a summary of the indications for non-contrasted CT: Contrast helps enhance certain body structures. [18F]Fluoride Positron-Emission Tomography (PET) and [18F]FDG PET for Assessment of Osteomyelitis of the Jaw in Comparison to Computed Tomography (CT) and Magnetic Resonance Imaging (MRI): A Prospective PET/CT and PET/MRI Pilot Study. In patients with elevated creatinine, withholding IV dye may be necessary. Patients with a mild allergy may be pre-medicated with an antihistamine or steroids before imaging. Evaluation of chronic obstructive pulmonary disease also does not require IV contrast. Skeletal Radiol. Iodinated contrast agents can cause reversible acute renal failure. Recent studies suggest that a combination of hydration, sodium bicarbonate, N-acetylcysteine, and decreased contrast volume may reduce this risk in high-risk populations.14,15, The question of whether this risk has been overstated has been raised in the medical literature. Muscular fascia lies deep to the subcutaneous layer. The most common contrast agents used with CT imaging are barium- and iodine-based. Clinical presentations include skin erythema without a well-defined border, increased skin temperature, swelling of the affected area, and regional lymphadenopathy and lymphangitis. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. CT is used to accurately differentiate between superficial cellulitis and deep cellulitis. Initial radiographs show soft tissue gas (without puncture wound) or are normal with high clinical suspicion of necrotizing fasciitis. 2001;176(5):1155-9. Barium suspension from fluoroscopy or CT will not produce an artifact on abdominal magnetic resonance imaging. the contents by NLM or the National Institutes of Health. 2001 Mar;39(2):277-303. doi: 10.1016/s0033-8389(05)70278-5. Disclaimer. Enter multiple addresses on separate lines or separate them with commas. x]6}W&VqeYjc=ZZgvmH]"2EV"KL D~x9n_O=~on~{,Je|Sn*nqis7^xgi| RUSpEzs_^c?nRW%74|q)PB#g3F|k9/tp8.r#5zv+t3/z,$f S$Uz`X, Suspected Osteomyelitis, Septic Arthritis, or Soft Tissue Infection (Excluding Spine and Diabetic Foot). 9. Many types of contrast agents can be used in computed tomography: oral, intravenous, rectal, and intrathecal. IV contrast may be used to visualize vasculature as well as the internal organs of the abdomen and pelvis. Rahmouni A, Chosidow O, Mathieu D et al. Careers. CT scanning is often the first imaging modality that is used because of its ease and availability at most medical institutions. Disease processes that involve calcifications may benefit from noncontrast-enhanced images because contrast may mask the appearance of calcifications. Since the epidermis is not involved, cellulitis is not transmitted by person-to-person contact. Weaver JS, Omar IM, Mar WA, Klauser AS, Winegar BA, Mlady GW, McCurdy WE, Taljanovic MS. Pol J Radiol. This absorption and scattering in turn results in higher CT attenuation values, or enhancement on CT images. 2020;368:m710. PDF CT Exams Contrast vs Non-Contrast Guide - Oregon Imaging Check for errors and try again. Contrast enhancement is also used to evaluate superior vena cava syndrome. All rights reserved. 5. Turecki M, Taljanovic M, Stubbs A et al. CT Head or brain with and without contrast Note: MRI Brain with/without contrast is preferred. 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. 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. Speak with a Radiologist: 541-284-4016 Scout film (a) and contrast-enhanced CT (b) shows intramuscular pockets of gas (arrows) in the left lateral thigh. endobj Unable to load your collection due to an error, Unable to load your delegates due to an error. 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. <> {"url":"/signup-modal-props.json?lang=us"}, Radswiki T, Carroll D, Knipe H, et al. FOIA Before Radiology. The specific agent and route of administration are based on clinical indications and patient factors. 07/16 RH /MF MRI Nomenclature for Musculoskeletal Infection. Before 2007 Nov-Dec;27(6):1723-36. doi: 10.1148/rg.276075033. The diagnostic algorithm for lung cancer screening is evolving. 1 0 obj 7 0 obj A 35-year-old male with necrotizing fasciitis of the right calf. 2021;50(12):2319-47. 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. Federal government websites often end in .gov or .mil. This risk is significantly increased in patients with chronic renal disease, diabetes, heart failure, and anemia. Would you like email updates of new search results? If youre a nurse practitioner who struggles with the same question, check out the following guide to contrast and CT scans. In uncomplicated cellulitis, CT demonstrates skin thickening, septation of the subcutaneous fat, and thickening of the underlying superficial fascia. Cellulitis | Radiology Reference Article | Radiopaedia.org 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. 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. . Suspected Osteomyelitis, Septic Arthritis, or Soft Tissue - ACR 2015;2015:587857. doi: 10.1155/2015/587857. 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). The site is secure.

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