sharing sensitive information, make sure youre on a federal Infect Dis Clin North Am. Saad A, Kho J, Almeer G, Azzopardi C, Botchu R. Br J Radiol. It is injected through an intravenous line during the examination. Contrast enhancement of the pulmonary arteries is key, as embolic disease is identified as abnormal filling defects within the pulmonary arteries (Figure 2). 1994;192(2):493-6. 4. In pleural effusion, CT assessment for the presence, location, and extent of the effusion does not require contrast. 3 0 obj As with barium agents, they must be diluted for CT compared with the concentrations used in fluoroscopy. Oral contrast can be administered through a nasogastric tube to minimize the risk of aspiration. myriad of non-infective erythematous rashes, Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. 2019;10(1):47. An official website of the United States government. Typically, CT focusing on vascular disease (e.g., aneurysm, dissection) or renal or pancreatic pathology may include noncontrast-enhanced images to identify calcifications.20 Contrast-enhanced studies would be performed on the same day, in the same setting. Next imaging study. 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 would delay a diagnosis in the trauma setting. Infection, inflammation, and edema of the lung parenchyma are usually well depicted on CT without contrast enhancement. Cellulitis occurs after disruption of the skin and invasion of the subcutaneous tissues by microorganisms that may be skin flora, such as beta-hemolytic streptococci (most often),Staphylococcus aureus(including methycillin-resistant), or other bacteria 9. Above this, there is a narrow, relatively hyperechoic epidermal-dermal layer. Evaluation of chronic obstructive pulmonary disease also does not require IV contrast. When does chest CT require contrast enhancement? 3. No circumscribed collection, or signs of bulbar or intraconal involvement (note the preservation of the normal intraorbital fat density). (ABRS) may develop orbital, intracranial, and vascular complications including orbital cellulitis, subperiosteal , abscess, intracranial abscess, cerebritis, cavernous sinus thrombosis and aneurysm. Case 1: orbital and periorbital cellulitis, see full revision history and disclosures. At the time the article was created The Radswiki had no recorded disclosures. Marked preseptal edema and discrete contrast enhancement in the area of the affected left upper eyelid. Potential Harms of Computed Tomography: The Role of Informed Consent. The soft-tissue air deep to the fascia is seen as multiple echogenic foci (arrows) on ultrasound study (b). 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. Normally the subcutaneous tissue is hypoechoic with few hyperechoic strands (representing connective tissue). and transmitted securely. 2020;368:m710. Fluid tracking along deep and intermuscular fascia, which can be seen in advanced cases (d). 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. Contrast-enhanced CT demonstrates a horse-shoe shaped perirectal air collection (arrows), extending into the subcutaneous tissues of the ischiorectal fossa and medial gluteal region (b). Please enable it to take advantage of the complete set of features! % endobj Iodinated contrast crosses the human placenta. A 53-year-old male with necrotizing fasciitis of the left knee. 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. Unable to load your collection due to an error, Unable to load your delegates due to an error. Other CT findings include increase soft-tissue attenuation, subcutaneous edema and inflammatory fat stranding, which can also be seen in cellulitis.2,2123 In a study by Wysoki et al. 2nd ed. A paranasal sinus pathology is . Scout film (a) and contrast-enhanced CT (b) shows intramuscular pockets of gas (arrows) in the left lateral thigh. 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. 2022 Mar 5;87:e141-e162. Working in the emergency department as a nurse practitioner, I order CT scans in my evaluation of patients every day. A 55-year-old male with necrotizing Fasciitis of the left thigh. Ultrasound is usually the first investigation to evaluate a clinical suspicion of cellulitis. 2. Compared to plain radiography, ultrasound, CT and MR provide higher sensitivity and specificity for the diagnosis of necrotizing fasciitis. N.p. N/A No CT WRIST LEFT WO CONTRAST (IMG3906) CT WRIST RIGHT WO CONTRAST(IMG3909) CT HAND LEFT WO CONTRAST (IMG3794) CT HAND RIGHT WO CONTRAST (IMG3797) 73200 The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score: a tool for distinguishing necrotizing fasciitis from other soft tissue infections. In patients with normal renal function, repeat measurement of serum creatinine is not recommended after outpatient administration of IV contrast agents.7. 8. Copyright 2023 The Cleveland Clinic Foundation. doi: 10.5114/pjr.2022.113825. Cellulitis. Sagittal CT reformation demonstrates linear fluid collection (arrow) deep to the rectus femoris muscle (b). Epidemiology Risk factors trauma foreign bodies All Rights Reserved. If youre ever stuck when it comes to the correct diagnostic imaging method for your patient, pick up the phone and call the radiologist or imaging facility with whom you work. Swartz M. Clinical Practice. Cellulitis can affect any region of the body, and commonly affects a lower limb. 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 Lactic acidosis has never been documented in patients with normal renal function who are receiving metformin. 1998;170(3):615-20. All rights reserved. Unauthorized use of these marks is strictly prohibited. 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. Check for errors and try again. In patients with normal renal function, repeat measurement of serum creatinine is not recommended after outpatient administration of intravenous contrast agents. 2022 Nov 25;10(12):2329. doi: 10.3390/microorganisms10122329. MRI Nomenclature for Musculoskeletal Infection. It results in pain, erythema, oedema, and warmth. no financial relationships to ineligible companies to disclose. endobj 2021;50(12):2319-47. 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). An official website of the United States government. Mediastinitis may likewise be iatrogenic or may spread from the oropharynx. 7. Cellulitis. 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. Contrast is not used in patients with head, extremity or spine trauma. Case 1: orbital and periorbital cellulitis, see full revision history and disclosures. AJR Am J Roentgenol. Order "WRIST" if only carpal area. Abdominal and/or pelvic pain-acute or chronic 2. Extensive streaky soft-tissue gas is seen extending along the fascial planes of the right thigh on radiograph. 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 <> Paz Maya S, Dualde Beltrn D, Lemercier P, Leiva-Salinas C. Necrotizing fasciitis: an urgent diagnosis. Kidney/ureteral stones With IV contrast 1. PMC At the time the article was last revised David Carroll had In certain situations, however, a contrast medium is essential. Above this, there is a narrow, relatively hyperechoic epidermal-dermal layer. Dr. Amy Levine answered. Reference article, Radiopaedia.org (Accessed on 01 May 2023) https://doi.org/10.53347/rID-15554. Uncomplicated cellulitis is usually treated conservatively with antibiotics and locally supportive measures. At our institution, the CT protocol includes concomitant injections in the upper-extremity veins, with imaging timed for venous phase enhancement (pulmonary venogram). A 39-year-old male with necrotizing fasciitis of the right ankle. Cellulitis. official website and that any information you provide is encrypted Cellulitis treatment usually includes a prescription oral antibiotic. Disease processes that involve calcifications may benefit from noncontrast-enhanced images because contrast may mask the appearance of calcifications. What is the rationale for the laboratory workup for suspected pheochromocytomas and paragangliomas? 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. The parapharyngeal space was the most commonly involved space. Cellulitis can affect any region of the body, and commonly affects a lower limb. 1998;170(3):615-20. CT LUMBAR SPINE W CONTRAST (IMG214) 72126 72129 72132 EXTREMITIES Fracture, Abnormal pathology. On MRI, the signal on T2-WI is variable depending on the etiology. Summary of imaging findings of necrotizing fasciitis. Contrast enhancement is also used to evaluate superior vena cava syndrome. 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. Peri-orbital cellulitis is of concern in children because it may be secondary to occult underlying bacterial sinusitis or, rarely, due . At the time the article was last revised David Carroll had This material may not otherwise be downloaded, copied, printed, stored, transmitted or reproduced in any medium, whether now known or later invented, except as authorized in writing by the AAFP. 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. Radiographics. 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. Yu J & Habib P. MR Imaging of Urgent Inflammatory and Infectious Conditions Affecting the Soft Tissues of the Musculoskeletal System. Ultrasound is usually the first investigation to evaluate a clinical suspicion of cellulitis. The PPV was 91.3% when more than one deep neck space was involved but only 50.0% in patients with isolated retropharyngeal abscesses. the contents by NLM or the National Institutes of Health. CT head without IV contrast Usually Not Appropriate . government site. Adams, James, and Erik D. Barton. Imaging of Musculoskeletal Soft-Tissue Infections in Clinical Practice: A Comprehensive Updated Review. %PDF-1.7 Cellulitis occurs after disruption of the skin and invasion of the subcutaneous tissues by microorganisms that may be skin flora, such as beta-haemolytic streptococci (most often),Staphylococcus aureus(including methycillin-resistant), or other bacteria 9. 5. Crit Rev Diagn Imaging. 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). 2004;350(9):904-12. Contrast can cause acute renal failure. Altogether findings are in line with preseptal cellulitis, with no signs of deeper . 30 0 obj MeSH 2019;10(1):47. National Library of Medicine E-mail: Received 2018 Jan 20; Revised 2018 Mar 2; Accepted 2018 Mar 8. 3 ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. This absorption and scattering in turn results in higher CT attenuation values, or enhancement on CT images. N Engl J Med. Although many radiology departments screen for shellfish allergy, there is no cross-reactivity between shellfish and iodinated contrast. Federal government websites often end in .gov or .mil. Copyright 2013 by the American Academy of Family Physicians. 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. However, contrast enhancement is used to evaluate suspected or known exudative effusions and empyema.6 It also aids the evaluation of metastatic or primary malignancy of the pleura, particularly in cases of occult disease, as enhancement and thickening of the pleura are of diagnostic interest. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI]>>/MediaBox[0 0 612 792]/Contents 30 0 R/Group<>/Tabs/S/StructParents 0>> Accessibility Cellulitis(rare plural: cellulitides) is an acute infection of the dermis and subcutaneous tissues without deep fascial or muscular involvement. 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. 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. The https:// ensures that you are connecting to the CT area of interest without IV contrast Usually Appropriate Varies Variant 7: Suspected soft tissue infection. Other contrast media, such as those used for magnetic resonance imaging or barium enemas, do not contain iodine. Cellulitis (rare plural: cellulitides) is an acute infection of the dermis and subcutaneous tissues without deep fascial or muscular involvement. BMJ. Copyright 2016 The Cleveland Clinic Foundation. 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. <>stream MR Imaging in Acute Infectious Cellulitis. Skin findings, pain out of proportion, and signs of systemic shock should alert the clinician to the possibility of necrotizing fasciitis. We do not capture any email address. Since the epidermis is not involved, cellulitis is not transmitted by person-to-person contact. If the infection spreads to deeper tissues, complications can occur, such as soft-tissue abscess,necrotising fasciitis,infectious myositis, and/or osteomyelitis. That said, it is seldom required for diagnosing cellulitis and is therefore usually ordered for suspected complications or to rule out alternative diagnoses in cases of an atypical presentation. Struk DW, Munk PL, Lee MJ, Ho SG, Worsley DF. 9. Malghem J, Lecouvet FE, Omoumi P, Maldague BE, Vande Berg BC. Skeletal Radiol. It is important to tell the technician and your doctor if you have had a previous allergic reaction to iodinated contrast. The site is secure. Creatinine cutoffs vary among institutions, but generally range between 1.5 and 2 mg per dL (132.6 to 176.8 mol per L) before alternative imaging strategies are considered.7 An increasing creatinine level that is still within normal limits is also concerning, and alternative imaging strategies should be considered. What are the treatment options for myasthenia gravis if first-line agents fail? This site needs JavaScript to work properly. Schmid M, Kossmann T, Duewell S. Differentiation of Necrotizing Fasciitis and Cellulitis Using MR Imaging. 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. Copyright 2023 American Academy of Family Physicians. Fugitt JB, Puckett ML, Quigley MM, Kerr SM. Special consideration should be given to geriatric patients, in whom cellulitis of the lower extremities is more likely to develop into thrombophlebitis. Clear communication between the physician and radiologist is essential for obtaining the most appropriate study at the lowest cost and risk to the patient. Interstitial lung disease 2. endobj Large volume of gas seen within the scrotum wall and scrotum sac on the scout image (curved black arrow), consistent with Fourniers gangrene. Fundic gland polyps: Should my patient stop taking PPIs? CT is commonly used to diagnose, stage, and plan treatment for lung cancer, other primary neoplastic processes involving the chest, and metastatic disease.2 The need for contrast varies on a case-by-case basis, and the benefits of contrast should be weighed against the potential risks in each patient. 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. Because there is a risk of aspiration-induced pulmonary edema with concentrated iodine-based contrast agents, patients must be carefully selected. 2020;368:m710. 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. Diagnosis of necrotizing soft tissue infections by computed tomography.

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