Bias, Repeatability and Reproducibility of Liver T1 Mapping With Variable Flip Angles.

BACKGROUND: Three-dimensional variable flip angle (VFA) methods are commonly used for T1 mapping of the liver, but there is no data on the accuracy, repeatability, and reproducibility of this technique in this organ in a multivendor setting. PURPOSE: To measure bias, repeatability, and reproducibility of VFA T1 mapping in the liver. STUDY TYPE: Prospective observational. POPULATION: Eight healthy volunteers, four women, with no known liver disease. FIELD STRENGTH/SEQUENCE: 1.5-T and 3.0-T; three-dimensional steady-state spoiled gradient echo with VFAs; Look-Locker. ASSESSMENT: Traveling volunteers were scanned twice each (30 minutes to 3 months apart) on six MRI scanners from three vendors (GE Healthcare, Philips Medical Systems, and Siemens Healthineers) at two field strengths. The maximum period between the first and last scans among all volunteers was 9 months. Volunteers were instructed to abstain from alcohol intake for at least 72 hours prior to each scan and avoid high cholesterol foods on the day of the scan. STATISTICAL TESTS: Repeated measures ANOVA, Student t-test, Levene's test of variances, and 95% significance level. The percent error relative to literature liver T1 in healthy volunteers was used to assess bias. The relative error (RE) due to intrascanner and interscanner variation in T1 measurements was used to assess repeatability and reproducibility. RESULTS: The 95% confidence interval (CI) on the mean bias and mean repeatability RE of VFA T1 in the healthy liver was 34 ± 6% and 10 ± 3%, respectively. The 95% CI on the mean reproducibility RE at 1.5 T and 3.0 T was 29 ± 7% and 25 ± 4%, respectively. DATA CONCLUSION: Bias, repeatability, and reproducibility of VFA T1 mapping in the liver in a multivendor setting are similar to those reported for breast, prostate, and brain. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 1.

Modeling the benefits and harms of surveillance for hepatocellular carcinoma: Information to support informed choices.

Surveillance by ultrasonography for hepatocellular carcinoma (HCC) for individuals with cirrhosis is recommended. There is debate regarding the effectiveness of surveillance in reducing mortality, and there is little information on the harms available to patients considering surveillance. The aim of this study was to provide estimates of both the benefit and harms of surveillance. A Markov model was built to simulate outcomes of individuals aged 50 years with well-compensated cirrhosis entering surveillance. Following identification of a focal lesion by ultrasound surveillance, further investigations were defined by the European Association for the Study of the Liver/European Organization for Research and Treatment of Cancer recall policy. Benefit and harm outcomes are expressed per 1,000 patients over 5 years. For every 1,000 patients in surveillance over 5 years, there are 13 fewer deaths (95% confidence interval [CI], 12-14) compared with no surveillance, equating to a number needed to screen to prevent one death from HCC of 77. In comparison, many more individuals experienced harm through surveillance. For every 1,000 patients, 150 (95% CI, 146-154) had one or more false-positive tests equating to a number needed to harm from surveillance of 7. As a consequence of a false-positive test, 65 individuals required at least one additional unnecessary computed tomography scan or magnetic resonance imaging and 39 required an unnecessary liver biopsy according to the recall policy. Surveillance benefits were sensitive to the incidence of HCC and the mortality benefit achieved by treatment. Harms were sensitive to the rates of false-positive testing and the frequency of liver biopsy. CONCLUSION: There is a balance between the small absolute mortality benefit to surveillance for HCC and the numerically more frequent harms resulting from false-positive testing. Implementation of the recently revised American Association for the Study of Liver Diseases recommendations is predicted to reduce harms from unnecessary liver biopsy. (Hepatology 2017;66:1546-1555).

Role of quantification of hepatic steatosis and future remnant volume in predicting hepatic dysfunction and complications after liver resection for colorectal metastases: a pilot study.

OBJECTIVES: Accurate prediction of safe remnant liver volume to minimize complications following liver resection remains challenging. The aim of this study was to assess whether quantification of steatosis improved the predictive value of preoperative volumetric analysis. METHODS: Thirty patients undergoing planned right or extended right hemi-hepatectomy for colorectal metastases were recruited prospectively. Magnetic resonance imaging was used to assess the level of hepatic steatosis and future remnant liver volume. These data were correlated with data on postoperative hepatic insufficiency, complications and hospital stay. Correlations of remnant percentage, remnant mass to patient mass and remnant mass to body surface area with and without steatosis measurements were assessed. RESULTS: In 10 of the 30 patients the planned liver resection was altered. Moderate-severe postoperative hepatic dysfunction was seen in 17 patients. Complications arose in 14 patients. The median level of steatosis was 3.8% (range: 1.2-17.6%), but was higher in patients (n= 10) who received preoperative chemotherapy (P= 0.124), in whom the median level was 4.8% (range: 1.5-17.6%). The strongest correlation was that of remnant liver mass to patient mass (r= 0.77, P < 0.001). However, the addition of steatosis quantification did not improve this correlation (r= 0.76, P < 0.001). CONCLUSIONS: This is the first study to combine volumetric with steatosis quantifications. No significant benefit was seen in this small pilot. However, these techniques may be useful in operative planning, particularly in patients receiving preoperative chemotherapy.

Large hepatocellular carcinoma: time to stop preoperative biopsy.

BACKGROUND: In Western countries, hepatocellular carcinoma (HCC) often presents at a large size, which is seen as a contraindication to transplantation and often resection. Although diagnosis by imaging and alpha-fetoprotein is usually straightforward, nonspecialist units continue to use biopsy to prove the diagnosis before transfer for specialist surgical opinion. We have looked at the impact of this on our practice. STUDY DESIGN: We retrospectively analyzed all large HCCs resected in our unit during the last 12 years. Survival data were calculated according to size and univariate and multivariate analyses were carried out to determine impact of preoperative, operative, and histologic factors affecting outcomes. RESULTS: We identified 85 large HCCs (> 3 cm) and classified 42 as giant (> 10 cm). Overall survival at 1, 3, and 5 years was 76%, 54%, and 51%. Size did not influence survival, although more complex surgical techniques were required for giant tumors. Predictors of poorer disease-free survival were positive resection margin (p < 0.001), multiple tumors (p = 0.003), macroscopic vascular invasion (p = 0.015), and preoperative lesion biopsy (p = 0.027). CONCLUSIONS: Our data shows excellent outcomes after resection for large HCC. This supports the management of such patients in large-volume units that are fully equipped and experienced in the management of these patients. Preoperative biopsy should be avoided, as this unnecessary maneuver appears to have worsened our longterm results.

Liver metastases in candidates for hepatic resection: comparison of helical CT and gadolinium- and SPIO-enhanced MR imaging.

PURPOSE: To prospectively compare accuracy of dynamic contrast material-enhanced thin-section multi-detector row helical computed tomography (CT), high-spatial-resolution three-dimensional (3D) dynamic gadolinium-enhanced magnetic resonance (MR) imaging, and superparamagnetic iron oxide (SPIO)-enhanced MR imaging with optimized gradient-echo (GRE) sequence for depiction of hepatic lesions; surgery and histologic analysis were the reference standard. MATERIALS AND METHODS: Local ethics committee approval was granted, and written informed consent was obtained. Fifty-eight patients (45 men, 13 women; age range, 47-82 years) with hepatic metastases were imaged with multi-detector row CT (3.2-mm section thickness), 3D dynamic gadolinium-enhanced MR imaging (2.5-mm effective section thickness), and SPIO-enhanced MR by using an optimized T2-weighted GRE sequence. Images were reviewed independently by two blinded observers who identified and localized lesions with a four-point confidence scale. Accuracy of each technique was measured with alternative free-response receiver operating characteristic analysis. Results were correlated with findings at surgery with intraoperative ultrasonography or histopathologic examination. Statistical differences among techniques for each observer were measured. RESULTS: Accuracy values for each observer for all metastases (n = 215) and 1.0-cm or smaller metastases (n = 80), respectively, follow: For CT, those for reader 1 were 0.82 and 0.65; for reader 2, 0.81 and 0.68. For gadolinium-enhanced MR imaging, those for reader 1 were 0.92 and 0.79; for reader 2, 0.90 and 0.76. For SPIO-enhanced MR imaging, those for reader 1 were 0.92 and 0.83; for reader 2, 0.92 and 0.81. For all metastases for both observers, there was no significant difference between MR techniques, but both were significantly more accurate than CT (P < .01). For metastases 1.0 cm or smaller and one observer, there was no significant difference between MR techniques, but both were more accurate than CT (P < .01); for the other observer, SPIO-enhanced MR imaging was more accurate than gadolinium-enhanced MR imaging (P < .05) and CT (P < .02), but there was no significant difference between gadolinium-enhanced MR imaging and CT (P = .2). CONCLUSION: Accuracy for gadolinium-enhanced MR imaging and SPIO-enhanced MR imaging was similar. Both techniques were significantly more accurate than CT.

Preoperative vascular imaging in pediatric liver transplantation.

BACKGROUND/PURPOSE: There is a considerable variation in the use of vascular imaging techniques in the preoperative assessment of children scheduled for liver transplantation. Duplex Doppler ultrasound scan (US), magnetic resonance angiography (MRA), and conventional angiography are used to varying extents. The authors compared the results of preoperative vascular imaging studies with operative findings to determine their accuracy and usefulness. METHODS: Results of preoperative vascular imaging in 37 consecutive children undergoing cadaveric liver transplantation were compared with operative findings. Those undergoing relatively elective transplantations were investigated by US and MRA (group 1), whereas those requiring urgent transplants were assessed only by US (group 2). RESULTS: The median age of the cohort (15 boys; 22 girls) was 4 years (19 days to 16 years) and the median weight was 17 kg (2.9 to 82 kg). In group 1 (n = 26), 20 children had a normal-caliber, patent portal vein at transplant and 6 had a narrow but patent portal vein requiring venous reconstruction in 4. The sensitivity and specificity of MRA in the detection of an abnormally narrow portal vein were 100% (6/6) and 95% (19/20), respectively. If reversed or absent flow in the portal vein on US was taken as an indication of a potentially abnormal vein, the sensitivity and specificity of Doppler US were 83% (5/6) and 95% (19/20), respectively. Magnetic resonance angiography revealed arterial anomalies in 4 children but failed to detect small accessory hepatic arteries in 5. The single patient with an aberrant vena cava was identified by MRA. In group 2 (n = 11), venous findings at operation and on US were concordant in 10 (91%) cases; one infant with reversed flow in the portal vein on US had a thrombosed vein at surgery. Magnetic resonance angiography was useful in 2 patient groups: those with reversed flow on Doppler US or suspected portal vein thrombosis in whom an abnormal portal vein was present in 86% (6/7) and infants with the biliary atresia splenic malformation syndrome who had multiple venous and arterial anomalies. CONCLUSIONS: A detailed Doppler examination of the hepatic vasculature by an experienced sonographer/radiologist provides sufficient vascular imaging for most children scheduled for cadaveric liver transplantation. Routine MRA is recommended in children with the biliary atresia splenic malformation syndrome and in those with abnormal duplex Doppler US findings. Although there are limited data in this study, MRA is also valuable in children with Budd-Chiari syndrome, liver tumors, or a previous portosystemic shunt.

Bile duct strictures after hepatobiliary surgery: assessment with MR cholangiography.

PURPOSE: To establish the accuracy of magnetic resonance (MR) cholangiography for diagnosis of postsurgical bile duct strictures. MATERIALS AND METHODS: Sixty-seven patients suspected of having bile duct strictures after liver transplantation (n = 54), cholecystectomy (n = 8), hepatic resection (n = 4), or pancreaticoduodenectomy (n = 1) underwent MR cholangiography. Thick-slab single-shot fast spin-echo (repetition time msec/echo time msec, 4,500/940) imaging was performed in the coronal through sagittal planes with rotation in 10 degrees increments, and contiguous thin-section images were obtained in the transverse and the optimal coronal oblique planes by using half-Fourier rapid acquisition with relaxation enhancement (1,900/96). Three blinded observers independently reviewed the MR images and recorded diagnostic features including presence of biliary stricture by using a five-point confidence scale. Receiver operating characteristic analysis was used to measure the accuracy of MR cholangiography. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. Final diagnosis was established at surgery (n = 29) and direct cholangiography (23 of 29) or at direct cholangiography, liver biopsy, and/or serial liver function tests (n = 38). RESULTS: Thirty-three of 67 patients had strictures confirmed with the reference standard. MR cholangiography enabled correct diagnosis and depicted the site of strictures in all cases. Findings of stricture at MR cholangiography were false-positive in five patients with moderate duct dilatation and caliber change at the level of the anastomosis. Mean accuracy, sensitivity, specificity, PPV, and NPV were 94%, 97%, 74%, 86%, and 96%, respectively. CONCLUSION: MR cholangiography is as sensitive as direct cholangiography for the assessment of bile duct strictures after hepatobiliary surgery but may lead to overestimation of the importance of duct dilatation and caliber change.

Colorectal hepatic metastases: detection with SPIO-enhanced breath-hold MR imaging--comparison of optimized sequences.

PURPOSE: To compare the accuracy of four breath-hold magnetic resonance (MR) imaging sequences to establish the most effective superparamagnetic iron oxide (SPIO)-enhanced sequence for detection of colorectal hepatic metastases. MATERIALS AND METHODS: Thirty-one patients with colorectal hepatic metastases underwent T1-weighted gradient-echo (GRE) and T2-weighted fast spin-echo (FSE) MR imaging before and after SPIO enhancement. Four sequences were optimized for lesion detection: T2-weighted FSE, multiecho data image combination (MEDIC), T2-weighted GRE with an 11-msec echo time (TE), and T2-weighted GRE with a 15-msec TE. Images were reviewed independently by three blinded observers. The accuracy of each sequence was measured by using alternative free-response receiver operating characteristic analysis. All results were correlated with findings at surgery, intraoperative ultrasonography, or histopathologic examination. Differences between the mean results of the three observers were measured by using the Student t test. RESULTS: Postcontrast T2-weighted GRE sequences were the most accurate and were significantly superior to postcontrast T2-weighted FSE and unenhanced sequences alone (P <.05). For all lesions that were malignant or smaller than 1 cm, respectively, mean accuracies of postcontrast sequences were 0.082 and 0.64 for T2-weighted FSE, 0.90 and 0.78 for MEDIC, 0.92 and 0.80 for GRE with an 11-msec TE, 0.93 and 0.82 for GRE with a 15-msec TE, and 0.81 and 0.62 for unenhanced sequences. CONCLUSION: Optimized SPIO-enhanced T2-weighted GRE combined with unenhanced T2-weighted FSE MR sequences were the most sensitive. Breath-hold FSE postcontrast sequences offer no improvement in sensitivity compared with unenhanced sequences alone.

Hepatocellular carcinoma in cirrhotic livers: double-contrast thin-section MR imaging with pathologic correlation of explanted tissue.

OBJECTIVE: The aim of our study was to determine the sensitivity of double-contrast MR imaging in the detection of hepatocellular carcinomas in patients with a cirrhotic liver. SUBJECTS AND METHODS: Thirty-one patients underwent double-contrast MR imaging and subsequent liver transplantation. Breath-hold T1- and T2-weighted MR images were obtained before and after administration of superparamagnetic iron oxide, and three-dimensional T1-weighted gradient-recalled echo MR images were obtained 10, 40, and 120 sec after a bolus injection of gadolinium. Hypervascular lesions that failed to take up superparamagnetic iron oxide were regarded as showing typical characteristics of hepatocellular carcinoma; lesions that had only one of these two characteristics (either hypervascularity or failure to take up superparamagnetic iron oxide) were regarded as highly suspicious for hepatocellular carcinoma. Radiology reports were correlated with pathology reports for the explanted livers. RESULTS: Thirty-two hepatocellular carcinomas were found in 14 of the 31 patients. Combining the number of MR imaging reports citing lesions that were "typical of hepatocellular carcinoma" with the number of those citing lesions that were "highly suspicious," we found that for 25 of 32 lesions, an accurate MR imaging diagnosis of hepatocellular carcinoma was made (overall sensitivity, 78%). These lesions included 10 of the 11 lesions that were larger than 20 mm (sensitivity, 91%), 12 of the 13 lesions that were 11-20 mm (sensitivity, 92%), and three of the eight lesions that were 10 mm or less (sensitivity, 38%). Nineteen (76%) of 25 lesions had characteristics considered typical of hepatocellular carcinoma; the remaining six lesions either failed to take up superparamagnetic iron oxide and were hypovascular or were hypervascular but showed some uptake of superparamagnetic iron oxide. CONCLUSION: In patients with a cirrhotic liver, double-contrast MR imaging is highly sensitive in the diagnosis of hepatocellular carcinomas of 10 mm or larger, but success in the identification of tumors smaller than 10 mm is still limited.