Iodinated contrast media (ICM) is one of the most frequently administered pharmaceuticals. In Canada, over 5.4 million computed tomography (CT) examinations were performed in 2019, of which 50% were contrast enhanced. Acute kidney injury (AKI) occurring after ICM administration was historically considered a common iatrogenic complication which was managed by screening patients, prophylactic strategies, and follow up evaluation of renal function. The Canadian Association of Radiologists (CAR) initially published guidelines on the prevention of contrast induced nephropathy in 2007, with an update in 2012. However, new developments in the field have led to the availability of safer contrast agents and changes in clinical practice, prompting a complete revision of the earlier recommendations. This revised guidance document was developed by a multidisciplinary CAR Working Group of radiologists and nephrologists, and summarizes changes in practice related to contrast administration, screening, and risk stratification since the last guideline. It reviews the scientific evidence for contrast associated AKI and provides consensus-based recommendations for its prevention and management in the Canadian healthcare context. This article is a joint publication in the Canadian Association of Radiologists Journal and Canadian Journal of Kidney Health and Disease, intended to inform both communities of practice.

Acute mesenteric ischemia is a life-threatening condition with a high mortality rate and is challenging to diagnose because patient symptoms and laboratory test results are often nonspecific. Acute mesenteric ischemia (AMI) is a life-threatening condition with a high mortality rate. The diagnosis of AMI is challenging because patient symptoms and laboratory test results are often nonspe...

Contrast media, including iodinated contrast media and gadolinium-based contrast agents, are commonly administered pharmaceuticals with excellent safety profiles. However, a minority of the population may experience a hypersensitivity reaction following intravenous administration. Hypersensitivity reactions can be immediate or delayed, and range from mild, such as urticaria, to severe, including anaphylaxis. There is emerging evidence that longstanding pretreatment protocols, such as diphenhydramine and corticosteroids, are ineffective and have the potential for side effects and other harms. Moreover, the evidence for efficacy on which this practice is based is weak and outdated. A joint collaborative working group of representatives from the Canadian Association of Radiologists and the Canadian Society of Allergy and Clinical Immunology was assembled to inform medical professionals and hospital policies regarding hypersensitivity reactions to contrast media. The objectives of the working group were to provide an overview of the epidemiology, physiology, risk factors, and types of hypersensitivity reactions; to synthesize the evidence for pretreatment strategies that minimize the risk of a breakthrough reaction for both iodinated contrast media and gadolinium-based contrast agents; to review the allergy investigations used to evaluate patients with a history of severe hypersensitivity reaction; and to provide an overview of existing guidelines. Following appraisal of the evidence, the working group established recommendations based on consensus in this practice guidance.

OBJECTIVE. The purpose of this article is to review how fat is detected on imaging and to discuss the differential diagnosis of fat-containing liver lesions. CONCLUSION. Fat is a highly useful feature in characterizing liver lesions on imaging. Although a variety of liver lesions can show fat on cross-sectional imaging, the presence of fat usually indicates that the lesion is of hepatocellular origin. Less commonly, nonhepatocellular fatty lesions may be distinguished by ancillary clinical and imaging features.

Background The independent contribution of each Liver Imaging Reporting and Data System (LI-RADS) CT or MRI ancillary feature (AF) has not been established. Purpose To evaluate the association of LI-RADS AFs with hepatocellular carcinoma (HCC) and malignancy while adjusting for LI-RADS major features through an individual participant data (IPD) meta-analysis. Materials and Methods Medline, Embase, Cochrane Central Register of Controlled Trials, and Scopus were searched from January 2014 to January 2022 for studies evaluating the diagnostic accuracy of CT and MRI for HCC using LI-RADS version 2014, 2017, or 2018. Using a one-step approach, IPD across studies were pooled. Adjusted odds ratios (ORs) and 95% CIs were derived from multivariable logistic regression models of each AF combined with major features except threshold growth (excluded because of infrequent reporting). Liver observation clustering was addressed at the study and participant levels through random intercepts. Risk of bias was assessed using a composite reference standard and Quality Assessment of Diagnostic Accuracy Studies 2. Results Twenty studies comprising 3091 observations (2456 adult participants; mean age, 59 years ± 11 [SD]; 1849 [75.3%] men) were included. In total, 89% (eight of nine) of AFs favoring malignancy were associated with malignancy and/or HCC, 80% (four of five) of AFs favoring HCC were associated with HCC, and 57% (four of seven) of AFs favoring benignity were negatively associated with HCC and/or malignancy. Nonenhancing capsule (OR = 3.50 [95% CI: 1.53, 8.01]) had the strongest association with HCC. Diffusion restriction (OR = 14.45 [95% CI: 9.82, 21.27]) and mild-moderate T2 hyperintensity (OR = 10.18 [95% CI: 7.17, 14.44]) had the strongest association with malignancy. The strongest negative associations with HCC were parallels blood pool enhancement (OR = 0.07 [95% CI: 0.01, 0.49]) and marked T2 hyperintensity (OR = 0.18 [95% CI: 0.07, 0.45]). Seventeen studies (85%) had a high risk of bias. Conclusion Most LI-RADS AFs were independently associated with HCC, malignancy, or benignity as intended when adjusting for major features. © RSNA, 2024 Supplemental material is available for this article. See also the editorial by Crivellaro in this issue.