Diagnosis of cardiac sarcoidosis using glucose metabolic rate from four-dimensional F-FDG PET/CT.

OBJECTIVE

F-Fludeoxyglucose (FDG) PET/CT is an effective tool for detecting active cardiac sarcoidosis (CS), but often has difficulty distinguishing CS lesions from physiological myocardial accumulation. We investigated the potential of the glucose metabolic rate (MR, mg/min/100mL) from four-dimensional FDG PET/CT in distinguishing between CS and physiological accumulation. Additionally, we compared CS delineation between MR and standardized uptake value (SUV).

METHODS

A total of 192 individuals with CS or suspected CS who underwent four-dimensional FDG PET/CT after 18 h fasting was enrolled. Ultimately, 45 individuals with CS and 14 patients with physiological accumulation, with SUV ≥ 2.7 accumulation in the left ventricular myocardium, were analyzed. The SUV, MR, and the ratio of MR to SUV (MR/SUV) were calculated for each lesion with SUV ≥ 2.7 using data acquired between 30 and 50 min on four-dimensional FDG PET/CT. In the CS group, lesion-to-normal myocardium contrast ratios on MR and SUV images were compared.

RESULTS

A total of 127 lesions from 45 individuals with CS and 43 physiological accumulations from 14 individuals were analyzed. The SUV, MR and MR/SUV for CS lesions were significantly lower than those for physiological accumulations (SUV, 4.26±1.35 vs. 6.06±3.28; MR, 1.91 ± 1.02 vs. 3.78 ± 2.11; MR/SUV, 0.43 ± 0.14 vs. 0.63 ± 0.14; p < 0.0001). Receiver operating characteristic analysis revealed that the ability to discriminate CS lesions from physiological accumulations yielded areas under the curves of 0.656, 0.808, and 0.849; sensitivities of 68, 76, and 73%; and specificities of 61, 72, and 84%, for SUV 4.525, MR 2.41, and MR/SUV 0.518. In the CS group, the contrast ratio of lesions was significantly greater on MR images than on SUV images (6.36 ± 6.17 vs. 2.54 ± 1.03, p < 0.0001).

CONCLUSIONS

MR from four-dimensional FDG PET/CT is a useful quantitative measure to distinguish CS lesions from physiological accumulation and enables better visualization of CS lesion contrast than SUV.