Clear cell, papillary, and chromophobe RCCs demonstrate different patterns of enhancement on two-time point clinical dynamic contrast-enhanced MR images, allowing their differentiation with high sensitivity and specificity.

Magnetic resonance (MR) imaging is useful in the characterization of renal masses. The MR imaging manifestations and pathologic diagnoses of 82 renal masses were reviewed and correlated. The MR imaging appearance of clear cell type renal cell carcinoma varies depending on the presence of cystic components, hemorrhage, and necrosis. Papillary renal cell carcinomas appear as well-encapsulated masses with homogeneous low signal intensity on T2-weighted images and homogeneous low-level enhancement after the intravenous administration of contrast material, or as cystic hemorrhagic masses with peripheral enhancing papillary projections. Transitional cell carcinoma may be seen as an irregular, enhancing filling defect in the pelvicaliceal system or ureter. Lymphomatous masses are usually hypointense relative to the renal cortex on T2-weighted images and enhance minimally on delayed gadolinium-enhanced images. Bulk fat is a distinguishing feature of angiomyolipoma. Oncocytoma has a variable and nonspecific appearance at MR imaging. MR imaging findings may allow the characterization of various renal masses and can provide valuable information for their clinical management.

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Intraoperative ultrasonography (US) of the pancreas is a versatile technique that provides excellent spatial and contrast resolution and real-time imaging capabilities, making it useful for diagnostic imaging as well as for guidance of laparoscopic and open operative procedures. Intraoperative US may be used for applications such as staging and localizing tumors; performing regional metastatic surveys; documenting arterial and venous patency; identifying endocrine tumors; distinguishing pancreatitis from a neoplasm; and guiding biopsy, duct cannulation, and drainage of abscesses or cysts. The scanning approach and technique vary according to the application, with many different equipment and transducer options and sterilization methods available. With increasing clinical demands for intraoperative US, it is essential that radiologists be familiar with its uses and technique. In addition, to properly perform intraoperative US and accurately interpret the images, knowledge of normal and variant pancreatic and vascular anatomy and relevant landmarks is needed. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.307105051/-/DC1.

Purpose:To assess the value of arterial spin-labeling (ASL) perfusion magnetic resonance (MR) imaging in the characterization of solid renal masses by using histopathologic findings as the standard of reference. Materials and Methods:This prospective study was compliant with HIPAA and approved by the institutional review board. Informed consent was obtained from all patients before imaging. Fortytwo consecutive patients suspected of having renal masses underwent ASL MR imaging before their routine 1.5-T clinical MR examination. Mean and peak tumor perfusion levels were obtained by one radiologist, who was blinded to the final histologic diagnosis, by using region of interest analysis. Perfusion values were correlated with histopathologic findings by using analysis of variance. A linear correlation model was used to evaluate the relationship between tumor size and perfusion in clear cell renal cell carcinoma (RCC). P , .05 was considered indicative of a statistically significant difference. Results:Histopathologic findings were available in 34 patients (28 men, six women; mean age 6 standard deviation, 60.4 years 6 11.7). The mean perfusion of papillary RCC (27.0 mL/min/100 g 6 15.1) was lower than that of clear cell RCC (171.6 mL/min/100 g 6 61.2, P = .001), chromophobe RCC (152.9 mL/min/100 g 6 80.7, P = .04), unclassified RCC (208.0 mL/min/100 g 6 41.1, P = .001), and oncocytoma (373.9 mL/min/100 g 6 99.2, P , .001). The mean and peak perfusion levels of oncocytoma (373.9 mL/ min/100 g 6 99.2 and 512.3 mL/min/100 g 6 146.0, respectively) were higher than those of papillary RCC (27.0 mL/min/100 g 6 15.1 and 78.2 mL/min/100 g 6 39.7, P , .001 for both), chromophobe RCC (152.9 mL/min/100 g 6 80.7 and 260.9 mL/min/100 g 6 61.9; P , .001 and P = .02, respectively), and unclassified RCC (208.0 mL/ min/100 g 6 41.1 and 273.3 mL/min/100 g 6 83.4; P = .01 and P = .03, respectively). The mean tumor perfusion of oncocytoma was higher than that of clear cell RCC (P , .001). Conclusion:ASL MR imaging enables distinction among different histopathologic diagnoses in renal masses on the basis of their perfusion level. Oncocytomas demonstrate higher perfusion levels than RCCs, and papillary RCCs exhibit lower perfusion levels than other RCC subtypes.q RSNA, 2012

Ultrasound is the most widely used imaging tool for hepatocellular carcinoma (HCC) screening and surveillance. Until now, this method has lacked standardized guidelines for interpretation, reporting, and management recommendations [1-5]. To address this need, the American College of Radiology (ACR) has developed the Ultrasound Liver Imaging Reporting and Data System (US LI-RADS) algorithm. The proposed algorithm has two components: detection scores and visualization scores. The detection score guides management and has three categories: US-1 Negative, US-2 Subthreshold, and US-3 Positive. The visualization score informs the expected sensitivity of the ultrasound examination and also has three categories: Visualization A: No or minimal limitations; Visualization B: Moderate limitations; and Visualization C: Severe limitations. Standardization in ultrasound utilization, reporting, and management in high-risk individuals has the capacity to improve communication with patients and referring physicians, unify screening and surveillance algorithms, impact outcomes, and supply quantitative data for future research.

Rationale and Objectives Renal perfusion measurements using non-invasive Arterial Spin Labeled (ASL) Magnetic Resonance Imaging (MRI) techniques are gaining interest. Currently, focus has been on perfusion in the context of renal transplant. Our objectives were to explore the use of ASL in patients with renal cancer, and to evaluate three-dimensional (3D) fast spin echo (FSE) acquisition, a robust volumetric imaging method for abdominal applications. We evaluate 3D ASL perfusion MRI in the kidneys compared to two-dimensional (2D) ASL in patients and healthy subjects. Materials and Methods Isotropic resolution (2.6×2.6×2.8 mm3) 3D ASL using segmented FSE was compared to 2D single-shot FSE. ASL used pseudo-continuous labeling, suppression of background signal, and synchronized breathing. Quantitative perfusion values and signal-to-noise-ratio (SNR) were compared between 3D and 2D ASL in four healthy volunteers and semi-quantitative assessments were made by four radiologists in four patients with known renal masses (primary renal cell carcinoma). Results Renal cortex perfusion in healthy subjects was 284 ± 21 mL/100g/min, with test-retest repeatability of 8.8 %. No significant differences were found between the quantitative perfusion value or SNR in volunteers between 3D and 2D ASL, or in 3D ASL with synchronized or free breathing. In patients, semi-quantitative assessment by radiologists showed no significant difference in image quality between 2D and 3D ASL. In one case, 2D ASL missed a high perfusion focus in a mass that was seen by 3D ASL. Conclusions 3D ASL renal perfusion imaging provides isotropic-resolution images, with comparable quantitative perfusion values and image SNR in similar imaging time to single-slice 2D ASL.