Assessment of colorectal liver metastases using MRI and CT: impact of observer experience on diagnostic performance and inter-observer reproducibility with histopathological correlation.

INTRODUCTION: To compare the diagnostic performance and inter-observer reproducibility of CT and MRI in detecting colorectal liver metastases (CRLM) of observers with different levels of experience. MATERIALS AND METHODS: Data from 51 CT and 54 MRI examinations of 105 patients with CRLM were analysed. Intraoperative and histopathological findings served as the reference standard. Analyses were performed by four observers with varying levels of experience regarding imaging of CRLM (reviewers A, B, C and D with respectively >20, >5, <1 and 0 years of experience). Per-segment sensitivity, specificity, Cohen's kappa (κ) for diagnosed segments and Intra-class Correlation Coefficients (ICC) for reported number of lesions were calculated. RESULTS: CT sensitivity and specificity was for reviewer A 89.71%/94.41%, B 78.50%/88.37%, C 63.55%/85.58%, D 84.11%/78.60% and regarding MRI A 90.40%/95.43%, B 74.40%/90.04%, C 60.00%/85.89% and D 65.60%/75.90%. The overall inter-observer agreement was higher for CT (κ=0.43, p<0.001; ICC=0.75, p<0.001) than MRI (κ=0.38, p<0.001; ICC=0.65, p<0.001). The experienced reviewers A and B achieved better agreement for MRI (κ=0.54, p<0.001; ICC=0.77, p<0.001) than CT (κ=0.52, p<0.00; ICC=0.76, p<0.001) unlike the less experienced C and D (MRI κ=0.38, ICC=0.63 and CT κ=0.41, ICC=0.74, respectively, p<0.001). CONCLUSIONS: The proficiency in detection of CRLM is significantly influenced by observer experience, although CT interpretation is less affected than MRI analysis.

1.5-T magnetic resonance-guided transgluteal biopsies of the prostate in patients with clinically suspected prostate cancer: technique and feasibility.

OBJECTIVES: The aim of this study was to examine the feasibility and safety of magnetic resonance-guided prostate biopsy (MRGBx) with a transgluteal approach in patients with cancer suspicious prostatic lesions. MATERIALS AND METHODS: This study was approved by the ethical committee. A total of 25 men with clinically suspected prostate cancer with increased prostate-specific antigen levels and at least 1 previous negative transrectal ultrasound-guided prostatic biopsy (TRUSBx) underwent diagnostic magnetic resonance (MR) imaging of the prostate. Cancer suspicious regions (CSR) were identified, and MRGBx with a transgluteal approach in a large closed-bore 1.5-T MR system was manually performed in coaxial technique, using transversal fat-suppressed T2-weighted true fast imaging with steady-state free precession sequences. Success rate, biopsy findings, side effects, procedure time, number of acquisitions for the repositioning of the needle guide, and length of the biopsy channel were documented. Follow-up was performed 24 months after the procedure. RESULTS: In diagnostic MR imaging of the prostate, a total of 40 CSRs were detected in 25 patients. All MRGBx procedures were technically successful and all CSRs were biopsied. The mean number of core biopsies per CSR was 3.3 ± 1.5 (range, 1-7). Histopathological analysis revealed adenocarcinoma in 35% (14/40), acute or chronic prostatitis in 30% (12/40), adenofibromyomatous changes in 22.5% (9/40), and no identifiable pathology in 17.5% (7/40) of CSRs, with a pathological overlap for chronic prostatitis and adenofibromyomatous changes in 1 patient with biopsies in 2 CSRs. No missed prostate cancer after MR-guided biopsy in clinical follow-up was detected. Mean procedure time was 31 ± 7 minutes (range, 21-46 minutes). Side effects were hematuria (n = 7), hematospermia (n = 3), combined hematuria/hematospermia (n = 2), and infection (n=1). CONCLUSION: Magnetic resonance-guided prostate biopsy of the prostate gland with a transgluteal approach is feasible, safe, and a promising technique for histological clarification of cancer suspicious lesions in patients with increased prostate-specific antigen levels after negative TRUSBx. Magnetic resonance-guided prostate biopsy offers a reasonable alternative to repeated TRUSBx for histological clarification of prostate cancer.

MR-compatible assistance system for biopsy in a high-field-strength system: initial results in patients with suspicious prostate lesions.

PURPOSE: To examine the feasibility and safety of magnetic resonance (MR)-guided biopsy by using a transgluteal approach in patients with suspicious prostate lesions by using an MR-compatible robotic system and a 1.5-T MR system. MATERIALS AND METHODS: The study was approved by the institutional review board of University Frankfurt, and informed consent was obtained from each patient. A total of 20 patients (age range, 57.8-71.9 years; mean age, 65.1 years) underwent biopsy in a closed-bore high-field-strength MR system. Biopsy was performed with an MR-compatible pneumatically driven robotic system. T1-weighted gradient-echo fast low-angle shot and T2-weighted true fast imaging with steady-state precession sequences were used to plan and guide the intervention with a transgluteal access on the external planning computer of the assistance system. The system calculated the trajectory and then moved the guiding arm to the insertion point. The cannula was advanced manually, and biopsies were performed with the coaxial technique by using a 15-gauge pencil tip needle. Intervention time, complications, and biopsy findings were documented. RESULTS: The MR-compatible robotic system did not interfere with image quality, nor did MR imaging cause dysfunction of the robot. In one patient, the interventionist caused a fail-safe system shutdown. This was due to inadvertent displacement of the guiding arm during cannula insertion. This problem was solved by increasing the displacement threshold. Accurate coaxial cannula biopsy could be performed in all subsequent patients. Sufficient histopathologic assessment was performed in 19 patients. Insufficient material was retrieved in the patient who experienced fail-safe system shutdown. The median intervention time was 39 minutes (23-65 minutes). No procedure-related complications were observed. CONCLUSION: Preliminary results indicate that MR-guided robot-assisted biopsy is feasible and can be performed safely with highly accurate cannula placement.

Assessment of liver fibrosis and steatosis in PBC with FibroScan, MRI, MR-spectroscopy, and serum markers.

BACKGROUND: In recent years noninvasive methods have been evaluated for the assessment of liver fibrosis predominantly in patients with viral hepatitis. In this study, transient elastography (FibroScan), magnetic resonance imaging (MRI), magnetic resonance (MR)-spectroscopy, and serum markers were compared in patients with primary biliary cirrhosis (PBC) for the assessment of liver fibrosis and steatosis. METHODS: Forty-five patients with PBC and histologic assessment of liver fibrosis received transient elastography and examinations for serum markers of fibrosis and steatosis. In addition, 41 out of 45 patients received contrast-enhanced MRI and 38 out of 45 patients received proton MR-spectroscopy. RESULTS: The adjusted accuracy (area under the receiver operating characteristic) for the diagnosis of histologic-stage > or = II for FibroScan, MRI-contrast enhancement and Forns index was 80%, 83%, and 69%, and for the diagnosis of liver cirrhosis 95%, 91%, and 94%, respectively. No correlation of histologic-stage was observed for FibroTest and AST to platelet ratio index. Histologic steatosis significantly correlated with body mass index (r=0.46), the SteatoTest (r=0.39), homeostasis model assessment of insulin resistance (r=0.46), and MR-spectroscopy (r=-0.76). The accuracy for the diagnosis of histologic steatosis was best with MR-spectroscopy (88%). CONCLUSIONS: Contrast-enhanced MRI and FibroScan can be used with comparable results for the assessment of liver fibrosis in patients with PBC and seem to supplement each other. MR-spectroscopy represents the best method for highly accurate noninvasive measurement of liver steatosis.