Effect of stereotactic body radiotherapy on regional metabolic liver function investigated in patients by dynamic [18F]FDGal PET/CT

Purpose Stereotactic body radiotherapy (SBRT) is increasingly used for treatment of liver tumors but the effect on metabolic liver function in surrounding tissue is largely unknown. Using 2-deoxy-2-[18F]fluoro-d-galactose ([18F]FDGal) positron emission tomography (PET)/computed tomography (CT), we aimed to determine a dose–response relationship between radiation dose and metabolic liver function as well as recovery. Procedures. One male subject with intrahepatic cholangiocarcinoma and five subjects (1 female, 4 male) with liver metastases from colorectal cancer (mCRC) underwent [18F]FDGal PET/CT before SBRT and after 1 and 3 months. The dose response was calculated using the data after 1 month and the relative recovery was evaluated after 3 months. All patients had normal liver function at time of inclusion. Results A linear dose–response relationship for the individual liver voxel dose was seen until approximately 30 Gy. By fitting a polynomial curve to data, a mean TD50 of 18 Gy was determined with a 95% CI from 12 to 26 Gy. After 3 months, a substantial recovery was observed except in tissue receiving more than 25 Gy. Conclusions [18F]FDGal PET/CT makes it possible to determine a dose–response relationship between radiation dose and metabolic liver function, here with a TD50 of 18 Gy (95% CI 12–26 Gy). Moreover, the method makes it possible to estimate metabolic recovery in liver tissue.

Prognostic Value of Metabolic Liver Function Tests: a Study on 711 Cirrhotic Patients

Background & Aims: The prognosis of cirrhotic patients is usually assessed by Child-Pugh and MELD scores. Metabolic liver function tests such as aminopyrine breath test (ABT) and indocyanine green clearance (IGC) have been shown to reveal hepatocellular dysfunction. The aim of this retrospective study was to compare the prognostic value of the MELD score, Child-Pugh score, ABT and IGC in a large cohort of cirrhotic patients. Methods: Between January 1996 and June 2008, 711 cirrhotic patients were included and the primary endpoint was survival without LT. The ROC curves with c-statistics, correlation coefficient and survival were calculated. Results: Metabolic function tests and scores were strongly correlated. At the time of evaluation, 111 patients had died and 520 had received a transplant. Prognostic ability (estimated by the AUROC curve) to predict survival without LT at 6 months was 0.662, 0.691, 0.738 and 0.715 for ABT, IGC, Child-Pugh score and MELD score, respectively. Similarly, at 1 year, AUROC was 0.738 for Child-Pugh score, 0.716 for MELD score, 0.693 for IGC clearance and 0.651 for ABT. Conclusions: Our results strongly confirm that IGC and ABT have a high prognostic value in cirrhotic patients, similar to Child-Pugh and MELD scores. They could be developed to routinely evaluate the prognosis of patients in addition to clinical and biochemical data. Key words: – – – – – – . Abbreviations: ABT: Aminopyrine Breath Test; AUROC: area under the receiver operating characteristics curve; CP score: Child-Pugh score; DRI: deceased donor risk index; IGC: Indocyanine Green Clearance; LT: Liver transplantation; MELD: Model for End stage Liver Disease.