PET/CT-Based Absorbed Dose Maps in 90Y Selective Internal Radiation Therapy Correlate with Spatial Changes in Liver Function Derived from Dynamic MRI.

Functional liver parenchyma can be damaged from treatment of liver malignancies with 90Y selective internal radiation therapy (SIRT). Evaluating functional parenchymal changes and developing an absorbed dose (AD)-toxicity model can assist the clinical management of patients receiving SIRT. We aimed to determine whether there is a correlation between 90Y PET AD voxel maps and spatial changes in the nontumoral liver (NTL) function derived from dynamic gadoxetic acid-enhanced MRI before and after SIRT. Methods: Dynamic gadoxetic acid-enhanced MRI scans were acquired before and after treatment for 11 patients undergoing 90Y SIRT. Gadoxetic acid uptake rate (k1) maps that directly quantify spatial liver parenchymal function were generated from MRI data. Voxel-based AD maps, derived from the 90Y PET/CT scans, were binned according to AD. Pre- and post-SIRT k1 maps were coregistered to the AD map. Absolute and percentage k1 loss in each bin was calculated as a measure of loss of liver function, and Spearman correlation coefficients between k1 loss and AD were evaluated for each patient. Average k1 loss over the patients was fit to a 3-parameter logistic function based on AD. Patients were further stratified into subgroups based on lesion type, baseline albumin-bilirubin scores and alanine transaminase levels, dose-volume effect, and number of SIRT treatments. Results: Significant positive correlations (ρ = 0.53-0.99, P < 0.001) between both absolute and percentage k1 loss and AD were observed in most patients (8/11). The average k1 loss over 9 patients also exhibited a significant strong correlation with AD (ρ ≥ 0.92, P < 0.001). The average percentage k1 loss of patients across AD bins was 28%, with a logistic function model demonstrating about a 25% k1 loss at about 100 Gy. Analysis between patient subgroups demonstrated that k1 loss was greater among patients with hepatocellular carcinoma, higher alanine transaminase levels, larger fractional volumes of NTL receiving an AD of 70 Gy or more, and sequential SIRT treatments. Conclusion: Novel application of multimodality imaging demonstrated a correlation between 90Y SIRT AD and spatial functional liver parenchymal degradation, indicating that a higher AD is associated with a larger loss of local hepatocyte function. With the developed response models, PET-derived AD maps can potentially be used prospectively to identify localized damage in liver and to enhance treatment strategies.

Prediction of Mortality and Hepatic Encephalopathy after Transjugular Intrahepatic Portosystemic Shunt Placement: Baseline and Longitudinal Body Composition Measurement.

PURPOSE: To investigate effects of baseline and early longitudinal body composition changes on mortality and hepatic encephalopathy (HE) after transjugular intrahepatic portosystemic shunt (TIPS). MATERIALS AND METHODS: This is a case-control study with analysis of a TIPS registry (1995-2020) including data from patients with cirrhosis with computed tomography (CT) scans obtained within 1 month before and 3 months after TIPS. Core muscle area (CMA), macroscopic subcutaneous adipose tissue (mSAT), macroscopic visceral adipose tissue (mVAT) area, and muscle adiposity index (MAI) on CT were obtained. Multipredictor Cox proportional hazards models were used to assess the effect of body composition variables on mortality or HE. RESULTS: In total, 280 patients (158 men; median age, 57.0 years; median Model for End-stage Liver Disease-sodium [MELD-Na] score, 14.0) were included. Thirty-four patients had post-TIPS imaging. Median baseline CMA was 68.3 cm2 (interquartile range, 57.7-83.5 cm2). Patients with higher baseline CMA had decreased risks of mortality (hazard ratio [HR]: 0.82; P = .04) and HE (HR: 0.82; P = .009). It improved prediction of mortality over MELD-Na and post-TIPS right atrial pressure alone (confidence interval = 0.729). An increase in CMA (HR: 0.60; P = .043) and mSAT (HR: 0.86; P = .022) or decrease in MAI (HR: 1.50; P = .049) from before to after TIPS was associated with a decreased risk of mortality. An increase in mSAT was associated with an increased risk of HE (HR: 1.11; P = .04). CONCLUSIONS: CMA on CT scan 1 month before TIPS placement predicts mortality and HE in patients with cirrhosis. Changes in body composition on CT measured 3 months after TIPS placement independently predict mortality and HE.