Abstract
ObjectivePrevious studies have shown that increased cardiac uptake of 18F-fluorodeoxyglucose (FDG) on positron emission tomography (PET) may be an indicator of myocardial injury after radiotherapy (RT). The primary objective of this study was to quantify cardiac subvolume dosimetry and 18F-FDG uptake on oncologic PET using a 17-segment model of the left ventricle (LV) and to identify dose limits related to changes in cardiac 18F-FDG uptake after RT.MethodsTwenty-four esophageal cancer (EC) patients who underwent consecutive oncologic 18F-FDG PET/CT scans at baseline and post-RT were enrolled in this study. The radiation dose and the 18F-FDG uptake were quantitatively analyzed based on a 17-segment model. The 18F-FDG uptake and doses to the basal, middle and apical regions, and the changes in the 18F-FDG uptake for different dose ranges were analyzed.ResultsA heterogeneous dose distribution was observed, and the basal region received a higher median mean dose (18.36 Gy) than the middle and apical regions (5.30 and 2.21 Gy, respectively). Segments 1, 2, 3, and 4 received the highest doses, all of which were greater than 10 Gy. Three patterns were observed for the myocardial 18F-FDG uptake in relation to the radiation dose before and after RT: an increase (5 patients), a decrease (13 patients), and no change (6 patients). In a pairing analysis, the 18F-FDG uptake after RT decreased by 28.93 and 12.12% in the low-dose segments (0–10 Gy and 10–20 Gy, respectively) and increased by 7.24% in the high-dose segments (20–30 Gy).ConclusionThe RT dose varies substantially within LV segments in patients receiving thoracic EC RT. Increased 18F-FDG uptake in the myocardium after RT was observed for doses above 20 Gy.
Highlights
Esophageal cancer (EC) is the 8th most common cancer and has the 6th highest cancer mortality rate worldwide [1]
Between January 2016 and December 2018, 24 patients with middle thoracic EC who underwent positron emission computed tomography (PET) scans at baseline and post-RT were retrospectively enrolled in this study
The results of the present study show a heterogeneous dose to the left ventricle (LV) for EC patients
Summary
Esophageal cancer (EC) is the 8th most common cancer and has the 6th highest cancer mortality rate worldwide [1]. Radiotherapy (RT) has become a primary treatment modality for patients with EC because of its effectiveness and relative safety. The heart lies near the middle esophagus and is inevitably irradiated during RT for middlestage EC patients. Advances in RT equipment and techniques have prolonged patient survival, delayed latent effects of radiation are currently being encountered in clinical practice [2, 3]. Previous studies have reported that cardiac toxicity may even diminish the survival gains obtained from anticancer therapy [4, 5]. Early observation of changes in cardiac function is extremely important for monitoring and evaluating the occurrence and development of radiation-induced heart disease (RIHD)
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