Radiation-Induced Cardiomyopathy Incidentally Detected on Oncology 18F-Fluorodeoxyglucose Positron Emission Tomography

Nuclear medicine imaging methods of early radiation-induced cardiotoxicity: a ten-year systematic review

Introduction

Radiotherapy has significantly improved cancer survival rates, but it also comes with certain unavoidable complications. Breast and thoracic irradiation, for instance, can unintentionally expose the heart to radiation, leading to damage at the cellular level within the myocardial structures. Detecting and monitoring radiation-induced heart disease early on is crucial, and several radionuclide imaging techniques have shown promise in this regard.

Method

In this 10-year review, we aimed to identify nuclear medicine imaging modalities that can effectively detect early cardiotoxicity following radiation therapy. Through a systematic search on PubMed, we selected nineteen relevant studies based on predefined criteria.

Results

The data suggest that incidental irradiation of the heart during breast or thoracic radiotherapy can cause early metabolic and perfusion changes. Nuclear imaging plays a prominent role in detecting these subclinical effects, which could potentially serve as predictors of late cardiac complications.

Discussion

However, further studies with larger populations, longer follow-up periods, and specific heart dosimetric data are needed to better understand the relationship between early detection of cardiac abnormalities and radiation-induced heart disease.

Cardiac metabolic changes on 18 F-positron emission tomography after thoracic radiotherapy predict for overall survival in esophageal cancer patients

PURPOSE

Heart doses have been shown to be predictive of cardiac toxicity and overall survival (OS) for esophageal cancer patients. There is potential for functional imaging to provide valuable cardiac information. The purpose of this study was to evaluate the cardiac metabolic dose-response using 18 F-deoxyglucose (FDG)-PET and to assess whether standard uptake value (SUV) changes in the heart were predictive of OS.

METHODS

Fifty-one patients with esophageal cancer treated with radiation who underwent pre- and post-treatment FDG-PET scans were retrospectively evaluated. Pre- and post-treatment PET-scans were rigidly registered to the planning CT for each patient. Pre-treatment to post-treatment absolute mean SUV (SUVmean) changes in the heart were calculated to assess dose-response. A dose-response curve was generated by binning each voxel in the heart into 10 Gy dose-bins and analyzing the SUVmean changes in each dose-bin. Multivariate cox proportional hazard models were used to assess whether pre-to-post treatment cardiac SUVmean changes predicted for OS.

RESULTS

The cardiac dose-response curve demonstrated a trend of increasing cardiac SUV changes as a function of dose with an average increase of 0.044 SUV for every 10 Gy dose bin. In multivariate analysis, disease stage and SUVmean change in the heart were predictive (p < 0.05) for OS.

CONCLUSIONS

Changes in pre- to post-treatment cardiac SUV were predictive of OS with patients having a higher pre- to post-treatment cardiac SUV change surviving longer.

Evaluating Positron Emission Tomography-Based Functional Imaging Changes in the Heart After Chemo-Radiation for Patients With Lung Cancer

PURPOSE

Studies have noted a link between radiation dose to the heart and overall survival (OS) for patients with lung cancer treated with chemoradiation. The purpose of this study was to characterize pre- to posttreatment cardiac metabolic changes using fluorodeoxyglucose/positron emission tomography (FDG-PET) images and to evaluate whether changes in cardiac metabolism predict for OS.

METHODS AND MATERIALS

Thirty-nine patients enrolled in a functional avoidance prospective study who had undergone pre- and postchemoradiation FDG-PET imaging were evaluated. For each patient, the pretreatment and posttreatment PET/CTs were rigidly registered to the planning CT, dose, and structure set. PET-based metabolic dose-response was assessed by comparing pretreatment to posttreatment mean standardized uptake values (SUVmean) in the heart as a function of dose-bin. OS analysis was performed by comparing SUVmean changes for patients who were alive or had died at last follow-up and by using a multivariate model to assess whether pre- to posttreatment SUVmean changes were a predictor of OS.

RESULTS

The dose-response curve revealed increasing changes in SUV as a function of cardiac dose with an average SUVmean increase of 1.7% per 10 Gy. Patients were followed for a median of 437 days (range, 201-1131 days). SUVmean change was significantly predictive of OS on multivariate analysis with a hazard ratio of 0.541 (95% confidence intervals, 0.312-0.937). Patients alive at follow-up had an average increase of 17.2% in cardiac SUVmean while patients that died had an average decrease in SUVmean decrease of 13.5% (P = .048).

CONCLUSIONS

Our data demonstrated that posttreatment SUV changes in the heart were significant indicators of dose-response and predictors of OS. The present work is hypothesis generating and must be validated in an independent cohort. If validated, our data show the potential for cardiac metabolic changes to be an early predictor for clinical outcomes.