endobj A 39-year-old male with necrotizing fasciitis of the right ankle. Accessibility A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, organs, and blood vessels. Postoperative sternal wound infections are not uncommon and range from cellulitis to frank osteomyelitis. 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. Fortunately, orbital fat provides intrinsic background contrast, and most orbital pathologies can be easily visualised without infusion of a contrast medium. Since the epidermis is not involved, cellulitis is not transmitted by person-to-person contact. Oral contrast is generally used for visualization of the abdomen and/or pelvis when there is suspicion of bowel pathology. Although classically a clinical diagnosis, imaging is a powerful adjunct to facilitate early diagnosis in equivocal cases. Address correspondence to: Dr David K Tso. CT is used to accurately differentiate between superficial cellulitis and deep cellulitis. Clipboard, Search History, and several other advanced features are temporarily unavailable. 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. When does chest CT require contrast enhancement? Next imaging study. 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. The diagnostic algorithm for lung cancer screening is evolving. 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 edema, areas of necrotizing cellulitis do not enhance, degree of enhancement depends on the post contrast delay. It is important to tell the technician and your doctor if you have had a previous allergic reaction to iodinated contrast. Because there is a risk of aspiration-induced pulmonary edema with concentrated iodine-based contrast agents, patients must be carefully selected. Lactic acidosis has never been documented in patients with normal renal function who are receiving metformin. BMJ. Cellulitis can affect any region of the body, and commonly affects a lower limb. Most healthcare facilities have protocols dictating the cutoff at which IV dye may be administered in patients with impaired renal function. CT and MR imaging of orbital inflammation | SpringerLink In the false-positive group, cellulitis was the most . There is no direct interaction between metformin and IV radiologic contrast agents. 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. No circumscribed collection, or signs of bulbar or intraconal involvement (note the preservation of the normal intraorbital fat density). Interstitial lung disease 2. Epub 2015 Apr 29. 2009;16(4):267-76. CT Orbit With and Without Contrast | East River Medical Imaging Insights Imaging. The .gov means its official. With respect to employing CT as an imaging modality, first one should be aware of the different ty. The type of contrast agent and route of administration can increase the diagnostic yield of the study ordered. myriad of non-infective erythematous rashes, ADVERTISEMENT: Supporters see fewer/no ads, Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. 3. PMC 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. Speak with a Radiologist: 541-284-4016 Iodinated contrast agents can cause reversible acute renal failure. 8600 Rockville Pike As with barium agents, they must be diluted for CT compared with the concentrations used in fluoroscopy. In pleural effusion, CT assessment for the presence, location, and extent of the effusion does not require contrast. A 64-year-old male with Fourniers gangrene with perforated diverticulitis. Normally the subcutaneous tissue is hypoechoic with few hyperechoic strands (representing connective tissue). without access to clinical information or CT results. During the injection you may feel flushed and get a metallic taste in your mouth. 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. Emerg Radiol. Abdominal and/or pelvic pain-acute or chronic 2. 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. This absorption and scattering in turn results in higher CT attenuation values, or enhancement on CT images. Above this, there is a narrow, relatively hyperechoic epidermal-dermal layer. myriad of non-infective erythematous rashes, Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. <>stream Ultrasonographic screening of clinically-suspected necrotizing fasciitis. Inflammatory cellulitis is frequently confused with infectious cellulitis. Jamal K, Mandel L, Jamal L, Gilani S. 'Out of hours' adult CT head interpretation by senior emergency department staff following an intensive teaching session: a prospective blinded pilot study of 405 patients. The US Preventive Services Task Force currently recommends low-dose CT without contrast, along with appropriate patient counseling, for patients with a history of smoking and an age range as detailed in the Task Force statement. 2009;39(10):957-71. A 55-year-old male with necrotizing Fasciitis of the left thigh. E-mail: Received 2018 Jan 20; Revised 2018 Mar 2; Accepted 2018 Mar 8. 4. On MRI, the signal on T2-WI is variable depending on the etiology. Interpretation of Computed Tomography Imaging of the Eye and - LWW Cellulitis | Radiology Reference Article | Radiopaedia.org Iodinated contrast should be avoided for two months before administration of iodine 131. Kidney/ureteral stones With IV contrast 1. What is the rationale for the laboratory workup for suspected pheochromocytomas and paragangliomas? 3. Crit Rev Diagn Imaging. Skeletal Radiol. Ultrasound is usually the first investigation to evaluate a clinical suspicion of cellulitis. Water-soluble, iodine-based contrast agents can also be given orally. 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). Peri-orbital and orbital cellulitis - BMJ Best Practice . government site. The overall PPV for the prediction of deep neck abscess with contrast-enhanced CT was 79.6%. American College of Radiology ACR Appropriateness Criteria Sinonasal 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. The https:// ensures that you are connecting to the The information provided is for educational purposes only. <>/ExtGState<>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI]>>/MediaBox[0 0 612 792]/Contents 30 0 R/Group<>/Tabs/S/StructParents 0>> N Engl J Med. CT of the Neck: Image Analysis and Reporting in the - RadioGraphics Additionally, systemic features such as fevers and rigors may also be present. Contrast-enhanced CT demonstrates air (arrows) and edema in the scrotum, surrounding the right testicle (a). Alaia E, Chhabra A, Simpfendorfer C et al. 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. Fascial thickening and involvement of multiple compartments is a sensitive finding on MRI. Above this, there is a narrow, relatively hyperechoic epidermal-dermal layer. Summary of imaging findings of necrotizing fasciitis. Alaia E, Chhabra A, Simpfendorfer C et al. Horton L, Jacobson J, Powell A, Fessell D, Hayes C. Sonography and Radiography of Soft-Tissue Foreign Bodies. Malghem J, Lecouvet FE, Omoumi P, Maldague BE, Vande Berg BC. 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). Bethesda, MD 20894, Web Policies Skeletal Radiol. 3 2. 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. 30 0 obj Premedication with antihistamines and corticosteroids is recommended in patients with a history of mild to moderate reactions to intravenous contrast agents. In Vivo MicroCT Monitoring of Osteomyelitis in a Rat Model. The parapharyngeal space was the most commonly involved space. Compared to plain radiography, ultrasound, CT and MR provide higher sensitivity and specificity for the diagnosis of necrotizing fasciitis. Muscular fascia lies deep to the subcutaneous layer. 1998;170(3):615-20. Clear communication between the physician and radiologist is essential for obtaining the most appropriate study at the lowest cost and risk to the patient. Order "HAND" if entire wrist and hand. FOIA endstream 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.
