Pitfalls and Misinterpretations of Cardiac Findings on PET/CT Imaging: A Careful Look at the Heart in Oncology Patients

Prediction of cardiac events following concurrent chemoradiation therapy for non-small-cell lung cancer using FDG PET

OBJECTIVE

No imaging biomarkers are available for the prediction of cardiac events following concurrent chemoradiation therapy (CCRT) for non-small-cell lung cancer (NSCLC). We evaluated whether F-18 fluorodeoxyglucose positron emission tomography (FDG PET) early after CCRT, in addition to cardiac dosimetry, could predict late cardiac events in NSCLC.

METHODS

We retrospectively enrolled 133 consecutive patients with locally advanced, unresectable stage III NSCLC, who underwent FDG PET early after CCRT and survived at least 6 months. The primary endpoint was cardiac event ≥ grade 2 according to the Common Terminology Criteria for Adverse Events (version 5.0). Myocardial FDG uptake was measured and its association with the risk of cardiac events was evaluated.

RESULTS

FDG PET was performed after a median interval of 11 days of completing CCRT. Overall, 42 (32%) patients experienced cardiac events during a median follow-up of 45 months. The mean heart dose, maximum left ventricular (LV) standardized uptake value (SUV), changes in maximum and mean LV SUV, right ventricular uptake, tumor stage, white blood cell count, and diabetes were associated with cardiac events in univariable analysis. In multivariable analysis, maximum LV SUV (cutoff > 12.84; hazard ratio [95% confidence interval] = 2.140 [1.140-4.016]; p = 0.018) was an independent predictor of cardiac events along with the mean heart dose (> 11.1 Gy; 3.646 [1.792-7.417]; p < 0.001) and tumor stage (IIIB; 1.986 [1.056-3.734]; p = 0.033). It remained predictive of cardiac events in those with higher mean heart dose but not in those with lower mean heart dose.

CONCLUSIONS

Early FDG PET after CCRT for NSCLC could aid in predicting late cardiac events, especially in patients with higher mean heart dose.

Series of myocardial FDG uptake requiring considerations of myocardial abnormalities in FDG-PET/CT

Distinct from cardiac PET performed with preparation to control physiological FDG uptake in the myocardium, standard FDG-PET/CT performed with 4-6 h of fasting will show variation in myocardial FDG uptake. For this reason, important signs of myocardial and pericardial abnormality revealed by myocardial FDG uptake tend to be overlooked. However, recognition of possible underlying disease will support further patient management to avoid complications due to the disease. This review demonstrates the mechanism of FDG uptake in the myocardium, discusses the factors affecting uptake, and provides notable image findings that may suggest underlying disease.

Association between FDG uptake in the right ventricular myocardium and cancer therapy-induced cardiotoxicity

BACKGROUND

The aim of this study was to investigate changes in myocardial uptake evaluated by oncologic 18F-fluorodeoxyglucose (FDG) PET/CT scans and to determine the relationship between myocardial FDG uptake and cancer therapy-induced cardiotoxicity in breast cancer patients who underwent anthracycline or trastuzumab.

METHODS

We reviewed 121 consecutive patients who underwent oncologic FDG PET/CT and echocardiography at baseline and post-therapy with anthracyclines or trastuzumab for breast cancer. Grade in LV wall, uptake pattern in LV wall, and the presence of RV wall uptake were assessed by visual analysis, and the mean SUV in the LV and RV walls and the change of SUV (ΔSUV) between baseline and post-therapy PET/CT were measured by quantitative analysis. Multiple logistic regression analyses were performed to evaluate the association between PET parameters and cardiotoxicity.

RESULTS

Fifteen patients (12%) showed cardiotoxicity after therapy. The cardiotoxic group tended to show more diffuse LV uptake, higher SUV, and ΔSUV of RV wall than the non-cardiotoxic group following therapy with anthracyclines or trastuzumab. Logistic regression analysis showed that the presence of RV wall uptake, SUV of RV wall (> 1.8), and ΔSUV of RV wall (> 0.4) were significantly associated with cardiotoxicity after controlling for age, radiotherapy, and treatment.

CONCLUSIONS

The presence of RV wall uptake and the increase of SUV of RV wall on post-therapy PET/CT were associated with cardiotoxicity in breast cancer patients who underwent anthracycline or trastuzumab. Oncologic FDG PET/CT scans can provide information regarding cancer therapy-induced cardiotoxicity as well as tumor response.

Multimodality Imaging Assessment of Fabry Disease

Fabry disease is a lysosomal storage disease with a variety of cardiac manifestations. Although not specific for a diagnosis of Fabry disease, certain cardiac imaging findings may be highly suggestive of the diagnosis of Fabry disease in previously undiagnosed patients or cardiac involvement for patients with a known diagnosis of Fabry disease. In this review, we explore the current applications of multimodality cardiac imaging in the diagnosis and monitoring of patients with Fabry disease. Additionally, data regarding tissue characterization by cardiac magnetic resonance imaging and novel nuclear imaging techniques and their role in evaluating phenotype development is discussed.

The impact of infection and inflammation in oncologic 18F-FDG PET/CT imaging

Sites of infection and inflammation can be misleading in oncology PET/CT imaging because these areas commonly show ¹⁸F-FDG activity. Caution in the interpretation must be taken to avoid the misdiagnosis of malignancy. Utilization of both CT findings as well as patient history can help differentiate benign infectious and inflammatory processes from malignancy, although occasionally additional work-up may be required. This article discusses the mechanism of ¹⁸F-FDG uptake in infection and inflammation with illustrative examples.