MR Prediction of Liver Function and Pathology Using Gd-EOB-DTPA: Effect of Liver Volume Consideration.

PURPOSE: To evaluate whether the diagnostic performance of Gd-EOB-DTPA-enhanced MRI in evaluating liver function and pathology is improved by considering liver volume (LV). METHODS: This retrospective study included 104 patients who underwent Gd-EOB-DTPA-enhanced MRI before liver surgery. For each patient, using the precontrast and hepatobiliary phase images, we calculated the increase rate of the liver-to-spleen signal intensity ratio (LSR), that is, the "ΔLSR," and the increase rate of the liver-to-muscle signal intensity ratio (LMR), that is, the "ΔLMR." ΔLSR × LV and ΔLMR × LV were also calculated. The correlation of each MR parameter with liver function data or liver pathology was assessed. The correlation coefficients were compared between ΔLSR (ΔLMR) and ΔLSR (ΔLMR) × LV. RESULTS: The correlation coefficient between ΔLSR (ΔLMR) × LV and cholinesterase was significantly higher than that between ΔLSR (ΔLMR) and cholinesterase. The correlation coefficient between ΔLSR (ΔLMR) × LV and the degree of fibrosis or necroinflammatory activity was significantly lower than that between ΔLSR (ΔLMR) and the degree of fibrosis or necroinflammatory activity. CONCLUSION: The inclusion of liver volume may improve Gd-EOB-DTPA-based predictions of liver function, but not in predictions of liver pathology.

Three-dimensional T2-weighted imaging for liver MRI: clinical values of tissue-specific variable refocusing flip-angle turbo spin echo imaging.

PURPOSE: To assess the clinical utility of tissue-specific variable refocusing flip-angle (VRFA) turbo-spin echo imaging for three-dimensional T2-weighted imaging (3D-T2WI) of the liver. MATERIALS AND METHODS: Fifty-nine patients were scanned with three types of fat-suppressed T2WI for the comparison: two-dimensional single-shot turbo spin echo T2WI (ssT2WI), 3D-T2WI with tissue-specific VRFA (VISTA-TSV), and 3D-T2WI with low-constant VRFA (VISTA). Qualitatively, artifacts in the left and right lobes of the liver and black-blood effects in the liver were compared using the Wilcoxon signed-rank test with the Bonferroni correction. The detection and correct characterization rates of liver lesions were compared using McNemar's test. RESULTS: VISTA-TSV showed reduced artifacts in the left and right lobes of the liver compared with VISTA (P < 0.017). The artifacts shown by VISTA-TSV were equivalent to those shown by ssT2WI. The black-blood effects of VISTA-TSV and VISTA were better than that of ssT2WI (P < 0.017). VISTA-TSV showed the best detection and correct characterization rate of liver lesions among the three imaging techniques (P < 0.05). CONCLUSION: 3D-T2WI with tissue-specific VRFA can reduce artifacts of the liver, sufficiently suppress the signal in blood vessels, and has a potential to improve the detection and correct characterization rates of liver lesions.

Apparent diffusion coefficient characteristics of various adrenal tumors.

PURPOSE: Using pathologically proven tumors and 3 methods of apparent diffusion coefficient (ADC) measurement, we examined the potential of diffusion-weighted imaging (DWI) to differentiate adrenal tumors. METHODS: We evaluated adrenal tumors of 52 patients who underwent magnetic resonance (MR) examination including DWI and adrenal resection or biopsy between July 2006 and August 2011. Tumors included 25 cortical adenomas, 14 pheochromocytomas, 6 adrenal metastases, and seven others. We defined the tumor's "solid" region as an enhancing area on contrast-enhanced MR or computed tomography (CT) and measured the ADC of the tumor's "entire" and "solid" regions within a region of interest (ROI) placed on an ADC map ("entire" and "solid" ADCs). We obtained a "minimum" ADC by placing an ROI in an area showing the lowest ADC within the "solid" region. We also calculated the ratio of "non-solid" area to "entire" tumor and compared the average "entire," "solid," and "minimum" ADCs and the ratio of "non-solid" area to "entire" tumor between benign and malignant groups. RESULTS: The average "entire" ADC was significantly higher for the benign (1.35 ± 0.38 × 10(-3) mm2/s) than malignant group (1.01 ± 0.17 × 10(-3) mm2/s), and the average "solid" and "minimum" ADC and the ratio of "non-solid" area to "entire" tumor did not differ significantly between the benign and malignant groups. CONCLUSION: The higher "entire" ADC value of the benign group, which might be obtained incidentally, can be considered dependent on the condition of necrosis, hemorrhage, and degeneration. ADC measurement of a tumor's "solid" region was not useful for differentiating pathologically proven adrenal tumors.