Kristina Ringe

Does Obesity Influence the Prognosis of Metastatic Renal Cell Carcinoma in Patients Treated with Vascular Endothelial Growth Factor–Targeted Therapy?

BACKGROUND Obesity increases the risk for renal cell carcinoma (RCC). However, it has only recently been identified as an independent positive prognostic factor for localized RCC. OBJECTIVE To determine whether obesity influences long-term prognosis in metastatic RCC patients receiving vascular endothelial growth factor-targeted therapy. DESIGN, SETTING, AND PARTICIPANTS In 116 patients with metastatic RCC who received antiangiogenic agents (sunitinib, sorafenib, axitinib, bevacizumab) in 2005-2010, we evaluated whether body mass index (BMI), a body surface area (BSA) above the European average, the visceral fat area (VFA), or s.c. fat area (SFA) were of predictive relevance. MEASUREMENTS BMI was categorized based on current World Health Organization definitions. BSA was stratified according to the European average for men (1.98 m(2)) and women (1.74 m(2)). VFA and SFA were dichotomized using the median of the observed distribution as the cutoff. The primary endpoints of this study were time to progression and overall survival time. RESULTS AND LIMITATIONS The whole population had median progression-free and overall survival times of 8.3 months and 20.5 months, respectively. In contrast to BMI and BSA, higher than average VFA and SFA levels were significant predictors of longer progression-free and overall survival times. The major limitations of this study are its retrospective design and its heterogeneous patient population. CONCLUSION This is the first study to identify high VFA and SFA levels as positive predictive biomarkers for patients who receive first-line antiangiogenic agents for metastatic RCC.

Hepatobiliary transit times of gadoxetate disodium (Primovist®) for protocol optimization of comprehensive MR imaging of the biliary system—What is normal?

OBJECTIVE The purpose of this study was to determine transit times for excretion of Gd-EOB-DTPA into different segments of the hepatobiliary system in patients with normal liver function. METHODS This retrospective study was IRB approved with a waiver of consent granted. 61 patients (39 female, 22 male, mean age 52.5 years) with normal liver and renal function who underwent contrast enhanced hepatic MRI after injection of 10 mL Gd-EOB-DTPA at 1.5T and 3T were included. Two readers evaluated all delayed images (3-20 min post contrast) for the presence of contrast agent in the intrahepatic bile ducts (IBD), the common bile duct (CBD), the gallbladder and the duodenum. A two-tailed, unpaired Students t-test with p<0.05 deemed significant was used to determine whether transit times were affected by patient gender, age or body mass index. RESULTS 20 min after contrast initiation, Gd-EOB-DTPA could be detected in the IBD and the CBD in all patients (100%); gallbladder reflux was visible in 53 (86.9%), duodenal excretion in 40 patients (65.5%), respectively. Mean transit times for contrast appearance in the various segments were as follows: IBD 12 min 13s; CBD 12 min 27 s; gallbladder 13 min 32s. Transit times were not significantly affected by patient gender, age or BMI. CONCLUSION Within 20 min post contrast initiation, Gd-EOB-DTPA can be expected in the IBD and the CBD in patients with normal liver function. However, functional information about the sphincter Oddi complex can be ascertained only in about two thirds of these patients within this timeframe.

Gadoxetate Disodium–Enhanced Hepatic MRI: Dose-Dependent Contrast Dynamics of Hepatic Parenchyma and Portal Vein

OBJECTIVE The purpose of this study was to investigate the relative enhancement characteristics of the hepatic parenchyma and portal vein during gadoxetate disodium-enhanced abdominal MRI and to assess whether contrast between the portal vein and the hepatic parenchyma can be improved with higher doses of gadoxetate disodium. MATERIALS AND METHODS A total of 102 patients (61 women, 41 men) underwent gadoxetate disodium-enhanced abdominal MRI. They received a weight-independent dose of 10 mL of gadoxetate disodium, corresponding to a dose spectrum of 0.02-0.06 mmol/kg body weight. The patients were assigned to one of three dose groups: recommended dose (0.02-0.03 mmol/kg), intermediate dose (0.03-0.045 mmol/kg), or high dose (0.045-0.06 mmol/kg). The signal-to-noise ratios for the portal vein, liver, and the portal vein-to-liver contrast-to-noise ratio were calculated for three consecutive arterial phases, one portal venous phase, and four delayed imaging phases. RESULTS The delayed phase images of the liver showed statistically significant dose dependency and greater enhancement in the intermediate- and high-dose groups (p < 0.01). Analogously, the portal vein also exhibited greater enhancement in the two higher-dose groups, but the difference was not statistically significant (p > 0.05). Regarding portal vein-to-liver contrast, all three groups had a dose-independent fast parallel increase from baseline toward maximum contrast followed by a steady decline in contrast with no statistically significant differences between dose groups (p > 0.05). CONCLUSION Portal vein-to-liver contrast during gadoxetate disodium-enhanced hepatic MRI cannot be improved within a dose spectrum of 0.025-0.06 mmol/kg body weight.

Respiratory-triggered Three-dimensional T2-weighted MR Cholangiography after Injection of Gadoxetate Disodium: Is It Still Reliable?

PURPOSE To test the null hypothesis that there is no quantitative or qualitative difference between respiratory-triggered three-dimensional (3D) T2-weighted magnetic resonance (MR) cholangiography performed before or after administration of gadoxetate disodium. MATERIALS AND METHODS For this retrospective HIPAA-compliant dual-center study, institutional review board approval was obtained, and a waiver of informed consent was granted. Between July and December 2008, 60 patients (age range, 18-82 years) who were referred for liver MR imaging with gadoxetate disodium underwent respiratory-triggered 3D MR cholangiography before and immediately after completion of portal venous phase contrast material-enhanced T1-weighted MR imaging. Quantitative signal-to-noise ratio (SNR) measurements were obtained in the extrahepatic biliary tract in both MR cholangiographic data sets in each patient. Qualitative assessment was performed by four readers with a four-point scale to assess the depiction of extra- and intrahepatic ducts up to the third order. Statistical analysis consisted of a one-sided Wilcoxon signed rank test, with a P value of less than .05 indicating a significant difference. RESULTS There was a significant decrease in mean SNR in the MR cholangiographic data set after injection of gadoxetate disodium. SNR was 96 + or - 50 [standard deviation] and 78 + or - 47 before and after contrast media administration, respectively (P < .0001). For all readers, qualitative differences were most obvious in the depiction of the common bile duct and second- and third-order biliary branches, with the precontrast MR cholangiographic data sets being preferred (P < .0001). Precontrast data sets were also significantly preferred in the assessment of the right and left hepatic ducts by all readers. CONCLUSION Gadoxetate disodium adversely affects respiratory-triggered 3D MR cholangiography, both qualitatively and quantitatively. We recommend that such a sequence be performed before injection of gadoxetate disodium.

Radiological diagnosis in cholangiocarcinoma: Application of computed tomography, magnetic resonance imaging, and positron emission tomography.

The purpose of radiological imaging in patients with suspected or known cholangiocarcinoma (CCA) is tumour detection, lesion characterization and assessment of resectability. Different imaging modalities are implemented complementary in the diagnostic work-up. Non-invasive imaging should be performed prior to invasive biliary procedures in order to avoid false positive results. For assessment of intraparenchymal tumour extension and evaluation of biliary and vascular invasion, MRI including MRCP and CT are the primarily used imaging modalities. The role of PET remains controversial with few studies showing benefit with the detection of unexpected metastatic spread, the differentiation between benign and malignant biliary strictures, and for discriminating post therapeutic changes and recurrent CCA.

Contrast enhanced liver MRI in patients with primary sclerosing cholangitis: inverse appearance of focal confluent fibrosis on delayed phase MR images with hepatocyte specific versus extracellular gadolinium based contrast agents.

RATIONALE AND OBJECTIVES To assess the enhancement pattern of focal confluent fibrosis (FCF) on contrast-enhanced hepatic magnetic resonance imaging (MRI) using hepatocyte-specific (Gd-EOB-DTPA) and extracellular (ECA) gadolinium-based contrast agents in patients with primary sclerosing cholangitis (PSC). MATERIALS AND METHODS After institutional review board approval, 10 patients with PSC (6 male, 4 female; 33-61 years) with 13 FCF were included in this retrospective study. All patients had a Gd-EOB-DTPA-enhanced liver MRI exam, and a comparison ECA-enhanced MRI. On each T1-weighted dynamic dataset, the signal intensity (SI) of FCF and the surrounding liver as well as the paraspinal muscle (M) were measured. In the Gd-EOB-DTPA group, hepatocyte phase images were also included. SI FCF/SI M, SI liver/SI M, and [(SI liver - SI FCF)/SI liver] were compared between the different contrast agents for each dynamic phase using the paired Students t-test. RESULTS There was no significant difference in SI FCF/SI M in all imaging phases. SI liver/SI M was significantly higher for the Gd-EOB-DTPA group in the delayed phase (P < .001), whereas there was no significant difference in all other imaging phases. In the Gd-EOB-DTPA group, mean [(SI liver - SI FCF)/SI liver] were as follows (values for ECA group in parentheses): unenhanced phase: 0.26 (0.26); arterial phase: 0.01 (-0.31); portal venous phase (PVP): -0.05 (-0.26); delayed phase (DP): 0.14 (-0.54); and hepatocyte phase: 0.26. Differences were significant for the DP (P < .001). CONCLUSIONS On delayed phase MR images the FCF-to-liver contrast is reversed with the lesions appearing hyperintense on ECA enhanced images and hypointense on Gd-EOB-DTPA-enhanced images.

Experimental Evaluation of the Heat Sink Effect in Hepatic Microwave Ablation

Purpose To demonstrate and quantify the heat sink effect in hepatic microwave ablation (MWA) in a standardized ex vivo model, and to analyze the influence of vessel distance and blood flow on lesion volume and shape. Materials and Methods 108 ex vivo MWA procedures were performed in freshly harvested pig livers. Antennas were inserted parallel to non-perfused and perfused (700,1400 ml/min) glass tubes (diameter 5mm) at different distances (10, 15, 20mm). Ablation zones (radius, area) were analyzed and compared (Kruskal-Wallis Test, Dunn’s multiple comparison Test). Temperature changes adjacent to the tubes were measured throughout the ablation cycle. Results Maximum temperature decreased significantly with increasing flow and distance (p<0.05). Compared to non-perfused tubes, ablation zones were significantly deformed by perfused tubes within 15mm distance to the antenna (p<0.05). At a flow rate of 700ml/min ablation zone radius was reduced to 37.2% and 80.1% at 10 and 15mm tube distance, respectively; ablation zone area was reduced to 50.5% and 89.7%, respectively. Conclusion Significant changes of ablation zones were demonstrated in a pig liver model. Considerable heat sink effect was observed within a diameter of 15mm around simulated vessels, dependent on flow rate. This has to be taken into account when ablating liver lesions close to vessels.

Recommendations on the use of magnetic resonance imaging in PSC‐A position statement from the International PSC Study Group

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disorder characterized by inflammation and fibrosis of the intra‐ and/or extrahepatic bile ducts. Magnetic resonance imaging (MRI) is a noninvasive imaging modality that can be used to diagnose PSC and detect disease related complications. Quantitative MRI technologies also have the potential to provide valuable prognostic information. Despite the potential of this imaging technology, the clinical application of MRI in the care of PSC patients and imaging standards vary across institutions. Moreover, a unified position statement about the role of MRI in the care of PSC patients, quality imaging standards, and its potential as a research tool is lacking. Conclusion: Members of the International PSC Study Group and radiologists from North America and Europe have compiled the following position statement to provide guidance regarding the application of MRI in the care of PSC patients, minimum imaging standards, and future areas of research. (Hepatology 2017;66:1675–1688).

Does overweight influence the prognosis of renal cell carcinoma? Results of a multicenter study.

To assess the impact of overweight on prognosis of renal cell carcinoma patients.

Effectiveness of a three-dimensional dual gradient echo two-point Dixon technique for the characterization of adrenal lesions at 3 Tesla

AbstractObjectiveTo compare the sensitivity, specificity, and diagnostic accuracy of fat-only datasets reconstructed using a two-point Dixon technique, with corresponding opposed-phase (OP) and in-phase (IP) datasets for characterization of adrenal lesions at 3 Tesla (T).MethodsFifty-nine patients (21 male, 38 female) with 66 adrenal lesions (49 adenomas, 17 nonadenomas) underwent 3D dual gradient-echo 3-T adrenal MR imaging with reconstruction of OP/IP and fat/water datasets. Sensitivity, specificity, and diagnostic accuracy were compared between OP/IP datasets, using the signal intensity index (SII), and fat/water datasets, using the fat fraction and fat ratio. Four radiologists qualitatively assessed OP/IP and fat-only datasets for reader confidence in lesion characterization and image quality.ResultsThere were significant differences between adenomas and nonadenomas with regard to mean SII, fat fraction, and fat ratio (P < 0.001). There was no significant difference in mean diagnostic accuracy among different evaluation methods using OP/IP and fat/water datasets. Mean readers’ scores for lesion characterization were significantly higher for adenomas than for nonadenomas using OP/IP and fat-only datasets. There was no significant difference between the two datasets regarding mean readers’ scores for image quality.ConclusionFat-only images can readily differentiate adrenal adenomas from nonadenomas, with diagnostic accuracy comparable to OP/IP images. Key Points • Incidental adrenal lesions are commonly encountered in radiology practice • MR has been used to identify lesions giving cause for concern. • 3T MR provides excellent demonstration of the effects of fat within structures • Fat-only 3T MR images can readily differentiate adrenal adenomas from nonadenomas