Tyler J. Fraum

Gadolinium-based contrast agents: A comprehensive risk assessment

Gadolinium‐based contrast agents (GBCAs) have been used in magnetic resonance imaging (MRI) since the 1980s and are now administered in up to 35% of all MRI examinations. While GBCAs were initially felt to carry minimal risk, the subsequent identification of GBCAs as the key etiologic factor in the development of nephrogenic systemic fibrosis (NSF) has raised concerns about the broader health impacts of gadolinium exposure. Clinicians, radiologists, and patients should be aware of the most up‐to‐date data pertaining to the risks of GBCA administration. Specific issues covered in this review article include immediate adverse reactions; pregnancy and lactation; and gadolinium deposition and toxicity, with a special focus on NSF. Practice recommendations based on the presented data, as well as current professional society guidelines, are provided for each section.

Differentiation of Hepatocellular Carcinoma from Other Hepatic Malignancies in Patients at Risk: Diagnostic Performance of the Liver Imaging Reporting and Data System Version 2014

Purpose To evaluate the diagnostic performance and interrater reliability of the Liver Imaging Reporting and Data System (LI-RADS) version 2014 in differentiating hepatocellular carcinoma (HCC) from non-HCC malignancy in a population of patients at risk for HCC. Materials and Methods This retrospective HIPAA-compliant institutional review board-approved study was exempt from informed consent. A total of 178 pathology-proven malignant liver masses were identified in 178 patients at risk for HCC but without established extrahepatic malignancy from August 2012 through August 2015. Two readers blinded to pathology findings and clinical follow-up data independently evaluated a liver protocol magnetic resonance or computed tomography study for each lesion and assigned LI-RADS categories, scoring all major and most ancillary features. Statistical analyses included the independent samples t test, x2 test, Fisher exact test, and Cohen k. Results This study included 136 HCCs and 42 non-HCC malignancies. Specificity and positive predictive value of an HCC imaging diagnosis (LR-5 or LR-5V) were 69.0% and 90.5%, respectively, for reader 1 (R1) and 88.3% and 95.5%, respectively, for reader 2 (R2). Tumor in vein was a common finding in patients with non-HCC malignancies (R1, 10 of 42 [23.8%]; R2, five of 42 [11.9%]). Exclusion of the LR-5V pathway improved specificity and positive predictive value for HCC to 83.3% and 92.9%, respectively, for R1 (six fewer false-positive findings) and 92.3% and 96.4%, respectively, for R2 (one fewer false-positive finding). Among masses with arterial phase hyperenhancement, the rim pattern was more common among non-HCC malignancies than among HCCs for both readers (R1: 24 of 36 [66.7%] vs 13 of 124, [10.5%], P < .001; R2: 27 of 35 [77.1%] vs 21 of 123 [17.1%], P < .001) (k = 0.76). Exclusion of rim arterial phase hyperenhancement as a means of satisfying LR-5 criteria also improved specificity and positive predictive value for HCC (R1, two fewer false-positive findings). Conclusion Modification of the algorithmic role of tumor in vein and rim arterial phase hyperenhancement improves the diagnostic performance of LI-RADS version 2014 in differentiating HCC from non-HCC malignancy.

Beyond Histologic Staging: Emerging Imaging Strategies in Colorectal Cancer with Special Focus on Magnetic Resonance Imaging.

Imaging plays an increasingly important role in the staging and management of colorectal cancer. In recent years, magnetic resonance imaging (MRI) has supplanted transrectal ultrasound as the preferred modality for the locoregional staging of rectal cancer. Furthermore, the advent of both diffusion-weighted imaging and hepatobiliary contrast agents has significantly enhanced the ability of MRI to detect colorectal liver metastases. In clinical practice, MRI routinely provides prognostic information, helps to guide surgical strategy, and determines the need for neoadjuvant therapies related to both the primary tumor and metastatic disease. Expanding on these roles for MRI, positron emission tomography (PET)/MRI is the newest clinical hybrid imaging modality and combines the metabolic information of PET with the high soft tissue contrast of MRI. The addition of PET/MRI to the clinical staging armamentarium has the potential to provide comprehensive state-of-the-art colorectal cancer staging in a single examination.

PET/MRI for Gastrointestinal Imaging: Current Clinical Status and Future Prospects

Positron emission tomography (PET)/computed tomography (CT) with 2-deoxy-2-[18F]fluoro-d-glucose (FDG) has become the standard of care for the initial staging and subsequent treatment response assessment for numerous gastrointestinal malignancies. However, it is often supplemented by magnetic resonance imaging (MRI) for local tumor staging. Hybrid PET/MRI scanners, which acquire PET data and MRI data simultaneously, have the potential to provide accurate whole-body staging in a single examination. Furthermore, to address certain limitations of FDG, many new PET tracers have been developed to probe distinctive aspects of tumor biology.

Mucinous Small Bowel Adenocarcinoma Mimicking Change to Internal Penetrating Phenotype in Well-controlled Crohn’s Disease

improvement project (ACQUIP). Alcohol use disorders identification test. Arch Intern Med. 1998;158:1789–95. 4. Sterling RK, Lissen E, Clumeck N, et al. Development of a simple noninvasive index to predict significant fibrosis in patients with HIV/HCV coinfection. Hepatol. 2006;43:1317–25. 5. Åberg F, Helenius-Hietala J, Puukka P, et al. Interaction between alcohol consumption and metabolic syndrome in predicting severe liver disease in the general population. Hepatol. 2018;67:2141–9.

CAPTURE: Consistently Acquired Projections for Tuned and Robust Estimation: A Self-Navigated Respiratory Motion Correction Approach

Objectives In this study, we present a fully automated and robust self-navigated approach to obtain 4-dimensional (4-D) motion-resolved images during free breathing. Materials and Methods The proposed method, Consistently Acquired Projections for Tuned and Robust Estimation (CAPTURE), is a variant of the stack-of-stars gradient-echo sequence. A 1-D navigator was consistently acquired at a fixed azimuthal angle for all stacks of spokes to reduce nonphysiological signal contamination due to system imperfections. The resulting projections were then “tuned” using complex phase rotation to adapt to scan-to-scan variations, followed by the detection of the respiratory curve. Four-dimensional motion-corrected and uncorrected images were then reconstructed via respiratory and temporal binning, respectively. This Health Insurance Portability and Accountability Act–compliant study was performed with Institutional Review Board approval. A phantom experiment was performed using a custom-made deformable motion phantom with an adjustable frequency and amplitude. For in vivo experiments, 10 healthy participants and 12 liver tumor patients provided informed consent and were imaged with the CAPTURE sequence. Two radiologists, blinded to which images were motion-corrected and which were not, independently reviewed the images and scored the image quality using a 5-point Likert scale. Results In the respiratory motion phantom experiment, CAPTURE reversed the effects of motion blurring and restored edge sharpness from 36% to 78% of that observed in the images from the static scan. Despite large intra- and intersubject variability in respiration patterns, CAPTURE successfully detected the respiratory motion signal in all participants and significantly improved the image quality according to the subjective radiological assessments of 2 raters (P < 0.05 for both raters) with a 1 to 2-point improvement in the median Likert scores across the whole set of participants. Small lesions (<1 cm in size) which might otherwise be missed on uncorrected images because of motion blurring were more clearly depicted on the CAPTURE images. Conclusions CAPTURE provides a robust and fully automated solution for obtaining 4-D motion-resolved images in a free-breathing setting. With its unique tuning feature, CAPTURE can adapt to large intersubject and interscan variations. CAPTURE also enables better lesion delineation because of improved image sharpness, thereby increasing the visibility of small lesions.

Epidemiology of Hepatic Steatosis at a Tertiary Care Center: An MRI-based Analysis

RATIONALE AND OBJECTIVES Little is known about the frequency and risk factors of hepatic steatosis in the tertiary care setting. Such knowledge is essential to clinicians making decisions about testing for this condition. Thus, our aim was to describe the epidemiology of hepatic steatosis, as captured by magnetic resonance imaging (MRI), at a tertiary care center. MATERIALS AND METHODS A near-consecutive cohort of 1006 adult patients underwent standard-of-care liver MRIs. Images were retrospectively processed to derive proton density fat fraction (PDFF) maps. Data from three spatially distinct regions of interest (ROIs) were aggregated to derive overall hepatic PDFF values. Demographic, anthropometric, clinical, and laboratory variables were included in a multivariate analysis to determine predictors of hepatic steatosis grades (based on established PDFF cutoffs). Hepatic steatosis grades derived from single vs aggregated ROIs were compared. RESULTS Hepatic steatosis was observed in 25% of patients (19% grade 1; 3% grade 2; 3% grade 3). Controlling for all other variables, the odds of hepatic steatosis increased by 7%-9% (P <.001) for each whole point increase in body mass index (BMI), whereas elevated serum bilirubin was associated with lower odds of hepatic steatosis (P = .002). Race, diabetes mellitus, dyslipidemia, and metabolic syndrome were not independently predictive of hepatic steatosis when controlling for other variables (eg, BMI). Employing single ROIs (rather than three aggregated ROIs) resulted in incorrect steatosis grading in up to 8.0% of patients. CONCLUSION Many adult patients undergoing liver MRI at a tertiary care center have hepatic steatosis, with larger BMIs as the only independent predictor of higher grades. This information can be used by clinicians at such centers to make evidence-based decisions about when to test for hepatic steatosis in their patients.