The Role of (18)F-FLT PET/CT in Assessing Early Response to Transarterial Radioembolization and Chemoembolization in Patients with Primary and Metastatic Liver Tumors

OBJECTIVES: Metastases and primary malignancies are common in the liver. Local ablative applications such as transarterial chemoembolization (TACE), and transarterial radioembolization (TARE) provide minimally invasive and safe treatment in unresectable liver tumors. Early detection of response to treatment prevents unnecessary toxicity and cost in non-responder patients and provides an earlier use of other options that may be effective. This study aimed to identify the role of (18)F-fluorothymidine (FLT) positron emission tomography/computed tomography (PET/CT) in the assessment of early response to TACE and TARE treatments in patients with unresectable primary and metastatic liver tumors METHODS: This single-center study included 63 patients who underwent (18)F-FLT PET/CT for response evaluation after TACE and TARE. After excluding 20 patients whose data were missing 43 TARE-receiving patients were analyzed. The compatibility of change in semi-quantitative values obtained from the (18)F-FLT PET/CT images with the treatment responses detected in (18)F-fluorodeoxyglucose PET/CT, CT, and MR images and survival was evaluated. RESULTS: There was no correlation between early metabolic, morphological response, and (18)F-FLT uptake pattern, and change in standardized uptake values (SUV) which were ΔSUV(max), ΔSUV(mean), ΔSUV(peak)., ΔSUV(mean), Δ SUV(peak) values. There was no significant correlation between (18)F-FLT uptake pattern, ΔSUV(max), ΔSUV(mean), ΔSUV(peak), and overall survival, progression-free survival (PFS) for the target lobe PFS for the whole-body. The survival distributions for the patients with >30% change in Δ SUV(max) and ΔSUV(peak) values were statistically significantly longer than the patients with <30% change (p<0.009 and p<0.024, respectively). CONCLUSION: There was significant longer PFS for target liver lobe in patients with more than 30% decrease in (18)F-FLT SUV(max) and SUV(peak) of the liver lesion in primary and metastatic unresectable liver tumors undergoing TARE.