Arterial Spin Labeled Perfusion MRI for the Evaluation of Response to Tyrosine Kinase Inhibition Therapy in Metastatic Renal Cell Carcinoma.

Background Tumor perfusion may inform therapeutic response and resistance in metastatic renal cell carcinoma (RCC) treated with antiangiogenic therapy. Purpose To determine if arterial spin labeled (ASL) MRI perfusion changes are associated with tumor response and disease progression in metastatic RCC treated with vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors (TKIs). Materials and Methods In this prospective study (ClinicalTrials.gov identifier: NCT00749320), metastatic RCC perfusion was measured with ASL MRI before and during sunitinib or pazopanib therapy between October 2008 and March 2014. Objective response rate (ORR) and progression-free survival (PFS) were calculated. Perfusion was compared between responders and nonresponders at baseline, at week 2, after cycle 2 (12 weeks), after cycle 4 (24 weeks), and at disease progression and compared with the ORR by using the Wilcoxon rank sum test and with PFS by using the log-rank test. Results Seventeen participants received sunitinib (mean age, 59 years ± 7.0 [standard deviation]; 11 men); 11 participants received pazopanib (mean age, 63 years ± 6.6; eight men). Responders had higher baseline tumor perfusion than nonresponders (mean, 404 mL/100 g/min ± 213 vs 199 mL/100 g/min ± 136; P = .02). Perfusion decreased from baseline to week 2 (-53 mL/100 g/min ± 31; P < .001), after cycle 2 (-65 mL/100 g/min ± 25; P < .001), and after cycle 4 (-79 mL/100 g/min ± 15; P = .008). Interval reduction in perfusion at those three time points was not associated with ORR (P = .63, .29, and .27, respectively) or PFS (P = .28, .27, and .32). Perfusion increased from cycle 4 to disease progression (51% ± 11; P < .001). Conclusion Arterial spin labeled perfusion MRI may assist in identifying responders to vascular endothelial growth factor receptor tyrosine kinase inhibitors and may help detect early evidence of disease progression in patients with metastatic renal cell carcinoma. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Goh and De Vita in this issue.

The utility of magnetic resonance imaging for noninvasive evaluation of diabetic nephropathy.

BACKGROUND: Noninvasive quantitative measurement of fibrosis in chronic kidney disease (CKD) would be desirable diagnostically and therapeutically but standard radiologic imaging is too variable for clinical usage. By applying a vibratory force, tissue shear wave stiffness can be measured by magnetic resonance elastography (MRE) that may correlate with progression of kidney fibrosis. Since decreased kidney perfusion decreases tissue turgor and stiffness, we combined newly available three-dimensional MRE shear stiffness measurements with MR arterial spin labeling (ASL) kidney blood flow rates to evaluate fibrosis in diabetic nephropathy. METHODS: Thirty individuals with diabetes and Stage 0-5 CKD and 13 control individuals without CKD underwent noncontrast MRE with concurrent ASL blood flow measurements. RESULTS: MRE cortical shear stiffness at 90 Hz was decreased significantly below controls in all CKD stages of diabetic nephropathy. Likewise, ASL blood flow decreased progressively from 480 ± 136 mL/min/100 g of cortical tissue in controls to 302 ± 95, 229 ± 7 and 152 ± 32 mL/min/100 g in Stages 3, 4 and 5 CKD, respectively. A magnetic resonance imaging (MRI) surrogate for the measured glomerular filtration fraction [surrogate filtration fraction = estimated glomerular filtration rate (eGFR)/ASL] decreased progressively from 0.21 ± 0.07 in controls to 0.16 ± 0.04 in Stage 3 and 0.10 ± 0.02 in Stage 4-5 CKD. CONCLUSIONS: In this pilot study, MRI with ASL blood flow rates can noninvasively measure decreasing kidney cortical tissue perfusion and, with eGFR, a decreasing surrogate filtration fraction in worsening diabetic nephropathy that appears to correlate with increasing fibrosis. Differing from the liver, MRE shear stiffness surprisingly decreases with worsening CKD, likely related to decreased tissue turgor from lower blood flow rates.

The Incidental Splenic Mass at CT: Does It Need Further Work-up? An Observational Study.

Purpose To evaluate whether an incidentally noted splenic mass at abdominal computed tomography (CT) requires further imaging work-up. Materials and Methods In this institutional review board-approved HIPAA-compliant retrospective study, a search of a CT database was performed for patients with splenic masses at CT examinations of the abdomen and chest from 2002 to 2008. Patients were divided into three groups: group 1, patients with a history of malignancy; group 2, patients with symptoms such as weight loss, fever, or pain related to the left upper quadrant and epigastrium; and group 3, patients with incidental findings. Patients' CT scans, follow-up examinations, and electronic medical records were reviewed. Final diagnoses of the causes of the masses were confirmed with imaging follow-up (83.9%), clinical follow-up (13.7%), and pathologic examination (2.4%). Results This study included 379 patients, 214 (56.5%) women and 165 (43.5%) men, with a mean age ± standard deviation of 59.3 years ± 15.3 (range, 21-97 years). There were 145 (38.3%) patients in the malignancy group, 29 (7.6%) patients in the symptomatic group, and 205 (54.1%) patients in the incidental group. The incidence of malignant splenic masses was 49 of 145 (33.8%) in the malignancy group, eight of 29 (27.6%) in the symptomatic group, and two of 205 (1.0%) in the incidental group (P < .0001). The incidental group consisted of new diagnoses of lymphoma in one (50%) patient and metastases from ovarian carcinoma in one (50%) patient. Malignant splenic masses in the incidental group were not indeterminate, because synchronous tumors in other organs were diagnostic of malignancy. Conclusion In an incidental splenic mass, the likelihood of malignancy is very low (1.0%). Therefore, follow-up of incidental splenic masses may not be indicated. © RSNA, 2018.

US LI-RADS: ultrasound liver imaging reporting and data system for screening and surveillance of hepatocellular carcinoma.

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.

Utility of transabdominal ultrasound for surveillance of known pancreatic cystic lesions: prospective evaluation with MRI as reference standard.

OBJECTIVES: To prospectively assess the utility of transabdominal ultrasound in surveillance of known pancreatic cystic lesions (PCL) using same day MRI as reference standard. METHODS: In an IRB-approved study with written informed consent, patients with known PCL underwent pancreas US on same day as surveillance MRI. US was performed blinded to same date MRI results. Transverse (TR), antero-posterior (AP), cranio-caudal (CC), and longest any plane diameter, were measured for each PCL at US and MRI. Visualization was correlated with patient (weight, abdominal diameter, thickness of abdominal fat, sex) and cyst (location, size, internal complexity) factors. RESULTS: 252 PCLs evaluated in 57 subjects (39 females; mean age 67 (range 39-86) yrs). Mean maximum PCL diameter 8.5 (range 2-92) mm. US identified 100% (5/5) of cysts ≥3 cm; 92% (12/13) ≥2 and <3 cm; 78% (43/55) ≥1 and <2 cm; 35% (27/78) ≥5 mm and <1 cm; and 16% (16/101) <5 mm. US visualization correlated with PCL location (<0.0001), size (p < 0.0001), patient gender (p = 0.005), participation of attending radiologist (p = 0.03); inversely with patient weight (p = 0.012) and AP abdominal diameter (p = 0.01). CONCLUSION: Many PCLs are visualized and accurately measured at follow-up with transabdominal ultrasound. Visualization correlates with lesion size, location, patient sex, weight, and abdominal diameter.

Effect of Stereotactic Body Radiotherapy on the Growth Kinetics and Enhancement Pattern of Primary Renal Tumors.

OBJECTIVE: The objective of our study was to assess the growth rate and enhancement of renal masses before and after treatment with stereotactic body radiotherapy (SBRT). MATERIALS AND METHODS: This retrospective study included all patients with renal masses who underwent SBRT during a 5-year period. Orthogonal measurements of renal masses were obtained on pre- and posttreatment CT or MRI. Pre- and posttreatment growth rates were compared for renal mass diameter and volume using the t test. Pre- and posttreatment tumor enhancement values were compared for tumors that underwent multiphasic contrast-enhanced MRI. RESULTS: Forty patients underwent SBRT for the treatment of 41 renal tumors: clear cell renal cell carcinomas (RCCs) (n = 16), papillary RCCs (n = 6), oncocytic neoplasms (n = 8), unclassified RCCs (n = 2), urothelial carcinoma (n = 1), and no pathologic diagnosis (n = 8). The mean maximum tumor diameter before treatment was 3.9 cm (range, 1.6-8.3 cm). Three hundred thirty-eight pre- and posttreatment imaging studies were analyzed: 214 MRI studies and 124 CT studies. The mean pre- and posttreatment lengths of observation were 416 days (range, 2-1800 days) and 561 days (83-1366 days), respectively. The mean pretreatment tumor growth rate of 0.68 cm/y decreased to -0.37 cm/y post treatment (p < 0.0001), and the mean tumor volume growth rate of 21.2 cm(3)/y before treatment decreased to -5.35 cm(3)/y after treatment (p = 0.002). Local control-defined as less than 5 mm of growth-was achieved in 38 of 41 (92.7%) tumors. The Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 showed progression in one tumor (2.4%), stability in 31 tumors (75.6%), partial response in eight tumors (19.5%), and complete response in one tumor (2.4%). No statistically significant change in tumor enhancement was shown (mean follow-up, 142 days; range, 7-581 days). CONCLUSION: Renal tumors treated with SBRT show statistically significant reductions in growth rate and tumor size after treatment but do not show statistically significant differences in enhancement in the initial (mean, 142 days) posttreatment period.

Volumetric Arterial Spin-labeled Perfusion Imaging of the Kidneys with a Three-dimensional Fast Spin Echo Acquisition.

RATIONALE AND OBJECTIVES: Renal perfusion measurements using noninvasive arterial spin-labeled (ASL) magnetic resonance imaging 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 magnetic resonance imaging 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 mm(3)) 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 semiquantitative 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/100 g/min, with test-retest repeatability of 8.8%. No significant differences were found between the quantitative perfusion value and SNR in volunteers between 3D ASL and 2D ASL, or in 3D ASL with synchronized or free breathing. In patients, semiquantitative assessment by radiologists showed no significant difference in image quality between 2D ASL 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.

Pemberton's sign: explained nearly 70 years later.

CONTEXT: Pemberton's sign is used to evaluate venous obstruction in patients with goiters. The sign is positive when bilateral arm elevation causes facial plethora. It has been attributed to a "cork effect" resulting from the thyroid obstructing the thoracic inlet, thereby increasing pressure on the venous system. According to some, the "cork effect" is caused by the thyroid descending into the thoracic inlet during arm elevation. According to others, the obstruction is due to elevation of the thoracic inlet against the thyroid. OBJECTIVE: We studied a 36-year-old man with a positive Pemberton's sign secondary to a goiter extending to the substernal region. DESIGN AND INTERVENTION: Clinical, biochemical, and radiological assessments were done. Magnetic resonance angiography of the neck was performed while the patient's arms were elevated and at his sides. After the imaging studies were completed, the patient underwent thyroidectomy. RESULTS: Magnetic resonance angiography demonstrated that there was no craniocaudal movement of the goiter relative to the thoracic inlet. However, the lateral aspect of the clavicle moved medially and inferiorly, obstructing the right external jugular vein and subclavian vein confluence. CONCLUSIONS: In the present case, we demonstrated that when eliciting Pemberton's sign, facial plethora and venous engorgement were due to the clavicles moving and compressing venous vasculature against the enlarged thyroid and not to a "cork effect." Rather, the clavicular motion observed during arm elevation could be compared to the movement of a "nutcracker" compressing major venous structures within a narrowed thoracic inlet against a relatively fixed and enlarged thyroid.

Imaging of liver transplant and its complications.

The role of diagnostic imaging in liver transplantation is reviewed with a focus on assessing for postoperative complications after adult orthotopic transplant. The normal postoperative appearance after liver transplant and imaging appearances of both vascular and nonvascular complications are discussed. The key role of Doppler ultrasound as the first-line imaging modality is highlighted.

Pancreatic surgery: a multidisciplinary assessment of the value of intraoperative US.

PURPOSE: To assess the value of intraoperative ultrasonography (US) for different types of pancreatic surgery. MATERIALS AND METHODS: An institutional review board-approved, HIPAA-compliant retrospective review with waiver of informed consent was performed to evaluate all cases of pancreatic surgery with intraoperative US or laparoscopic US that occurred at a single institution during a 10-year period. Surgical notes, radiologic images, and clinical data for each surgical procedure and subsequent clinical course were reviewed by pancreatic surgeons and radiologists. Presumptive diagnosis, type of surgical procedure performed, and final pathologic data were recorded. A relative value score was established by consensus and assigned to each case with a grade of 0-3, which indicated the value of the intraoperative or laparoscopic US. The type of operation and pathologic data were compared in each of the value score groups. Categoric variables were compared by using either χ(2) or Fisher exact test. RESULTS: One hundred ninety-three intraoperative or laparoscopic US procedures were performed in 189 patients. Of the patients, there were 102 men and 87 women. The mean age was 57.8 years (range, 18-86 years). Intraoperative or laparoscopic US value scores were as follows: value score 0, 3.6%; value score 1, 11.9%; value score 2, 31.1%; and value score 3, 53.4%. The most common contribution that resulted in a high score (value score 3) was facilitation of technical performance of the surgery (n = 60). High value score was significantly associated with performance of pancreatitis-related surgery (P < .001). The surgical indication that most commonly resulted in a low value score of 0 or 1 was staging of pancreatic cancers. All cases that received a score of 0 occurred in the laparoscopic adenocarcinoma surgical setting (staging or pancreatic biopsy). CONCLUSION: Intraoperative or laparoscopic US can be a valuable procedure in multiple types of surgical procedures that involve the pancreas and shows clear patterns of value in the different types of surgery.

Need for intraoperative ultrasound and surgical recommendation for partial nephrectomy: correlation with tumor imaging features and urologist practice patterns.

PURPOSE: This study aimed to evaluate the need for intraoperative ultrasound (IOUS) and recommendation for surgical approach in the resection of renal tumors through a survey of practicing urologists, with correlation to tumor imaging features and urologist practice pattern. MATERIALS AND METHODS: An institutional review board-approved retrospective review, compliant with the Health Insurance Portability and Accountability Act, of 44 renal tumors that underwent laparoscopic partial nephrectomy at the study institution was performed. The numeric component of the RENAL nephrometry score (radius [diameter], % exophytic, nearness [to collecting system/renal sinus], location) was calculated for each case using preoperative computed tomography/magnetic resonance imaging. Five anonymized images of each tumor were presented to 4 academic urologists with varying practice patterns. Reviewers independently scored each case for its need for IOUS, for recommendation of a surgical technique, and for the difficulty of the proposed surgery. RESULTS: The RENAL scores were as follows: RENAL 1 (low complexity, score 4-6; n = 19); RENAL 2 (moderate complexity, score 7-9; n = 23); RENAL 3 (high complexity, score 10-12; n = 2). The only RENAL score component significantly influencing need for IOUS was percentage exophytic (P = 0.00002). There was an inverse relationship between normalized and averaged need for IOUS and percentage exophytic (P < 0.0001). The predominant influence for recommendation of surgical method was the reviewer him/herself, with each reviewer's recommendations closely matching his/her practice pattern. Size and percentage exophytic represented the only tumor features significantly (P = 0.03) influencing surgical recommendation. CONCLUSIONS: There was a significant difference in the perceived need for IOUS and surgical recommendation when 4 academic urologists reviewed a series of renal masses requiring resection. Percentage exophytic correlated inversely with need for IOUS. Urologist's practice pattern and tumor size and percentage exophytic were most predictive of surgical recommendation.

Intraoperative ultrasonography of the pancreas.

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.

Magnetic resonance imaging of renal masses.

The increasing frequency of incidentally detected renal masses supports the need for accurate imaging characterization to avoid unnecessary surgery/interventional procedures. Furthermore, the need for accurate presurgical diagnosis of specific histologic subtypes of renal malignancies is increasingly important as advances in understanding of tumor biology direct targeted courses of therapy. Magnetic resonance imaging is uniquely suited for the evaluation of renal masses because of its ability to provide excellent soft-tissue contrast and demonstration of enhancement, as well as its multiplanar capabilities. Although the spectrum of masses that may occur in the kidneys is broad, specific imaging features may assist in their accurate diagnosis. Examples of the imaging appearance of common and uncommon renal masses are provided along with a protocol for comprehensive magnetic resonance examination of the kidneys.

Renal cell carcinoma: dynamic contrast-enhanced MR imaging for differentiation of tumor subtypes--correlation with pathologic findings.

PURPOSE: To retrospectively evaluate whether the enhancement patterns of pathologically proved clear cell, papillary, and chromophobe renal cell carcinomas (RCCs) measured on clinical dynamic contrast agent-enhanced magnetic resonance (MR) images permit accurate diagnosis of RCC subtype. MATERIALS AND METHODS: This study was Institutional Review Board approved and HIPAA compliant; informed consent was waived. One hundred twelve patients (76 men, 36 women; age range, 25-88 years; mean age, 58.1 years) underwent MR imaging of 113 renal masses (mean diameter, 5.4 cm) with pathologic diagnoses of clear cell (n = 75), papillary (n = 28), or chromophobe (n = 10) RCC. A 1.5-T clinical MR protocol was used before and after (corticomedullary and nephrographic phases) intravenous administration of contrast agent. Region-of-interest measurements within tumor and uninvolved renal cortex were used to calculate percentage signal intensity change and tumor-to-cortex enhancement index. Subtype groups were compared by using linear mixed-effects models. Receiver operating characteristic (ROC) curve analysis was performed for the comparison of clear cell and papillary RCCs. RESULTS: On both the corticomedullary and nephrographic phase images, clear cell RCCs showed greater signal intensity change (205.6% and 247.1%, respectively) than did papillary RCCs (32.1% and 96.6%, respectively) (P < .001). Chromophobe RCCs showed intermediate change (109.9% and 192.5%, respectively). The tumor-to-cortex enhancement indexes at corticomedullary and nephrographic phases were largest for clear cell RCCs (1.4 and 1.2, respectively), smallest for papillary RCCs (0.2 and 0.4, respectively), and intermediate for chromophobe RCCs (0.6 and 0.8, respectively). Signal intensity changes on corticomedullary phase images were the most effective parameter for distinguishing clear cell and papillary RCC (area under ROC curve, 0.99); a threshold value of 84% permitted distinction with 93% sensitivity and 96% specificity. CONCLUSION: 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.

Current techniques in imaging of fistula in ano: three-dimensional endoanal ultrasound and magnetic resonance imaging.

Perianal fistula is an abnormal communication between the anal canal and perianal skin. The majority of perianal fistulous disease results from either cryptoglandular inflammation or Crohn's disease. These groups differ in pathophysiology, prognosis, and strategies for imaging and treatment. Endoanal ultrasound and magnetic resonance imaging represent current imaging strategies for evaluating perianal fistulas and may be used alone or in combination. The use of three-dimensional technique and peroxide fistulography optimize the ultrasound evaluation of perianal fistula. The use of multiple imaging planes and sequences including fat suppression and contrast enhancement optimize the magnetic resonance imaging protocol. Examples of the imaging appearance of perianal fistulas and a proposed flowchart for imaging modality selection are provided.

Comparison of Dynamic Expiratory CT With Bronchoscopy for Diagnosing Airway Malacia: A Pilot Evaluation.

OBJECTIVE: To assess the accuracy of dynamic expiratory CT for detecting airway malacia using bronchoscopy as the diagnostic "gold standard." MATERIALS AND METHODS: A computerized hospital information system was used to retrospectively identify all patients with bronchoscopically proven airway malacia referred for CT airway imaging at our institution during a 19-month period. CT was performed within 1 week of bronchoscopy. All patients were scanned with a standard protocol, including end-inspiratory and dynamic expiratory volumetric imaging, using an eight-detector multislice helical CT scanner. For both CT and bronchoscopy, malacia was defined as >/= 50% expiratory reduction of the airway lumen. CT and bronchoscopic findings were subsequently jointly reviewed by the radiologist and bronchoscopist for concordance. RESULTS: Twenty-nine patients (12 men and 17 women; mean age, 60 years; range, 36 to 79 years) comprised the study cohort. CT correctly diagnosed malacia in 28 of 29 patients (97%). The most common presenting symptoms were dyspnea in 20 patients (69%), severe or persistent cough in 16 patients (55%), and recurrent infection in 7 patients (24%). The estimated radiation dose (expressed as dose-length product) for the dual-phase study is 508 mGy-cm, which is comparable to a routine chest CT. CONCLUSION: Dynamic expiratory CT is a highly sensitive method for detecting airway malacia and has the potential to serve as an effective, noninvasive test for diagnosing this condition.