Comparative study of 18F-FDG coincidence imaging and 67Ga imaging in sarcoidosis

Objective: To compare 18F-fluorodeoxyglucose (FDG) coincidence imaging and 67Ga imaging in diagnosis and therapeutic monitoring in sarcoidosis. Methods: Seventeen patients underwent 18F-FDG coincidence imaging, among them 11 cases received 67Ga imaging in addition. The uptakes of the tracer in the mediastinal and pulmonary hilar lymphnodes were judged by visual method with the uptakes in the lymphnodes surpassing markedly that in the surrounding lung tissue to be regarded as positive. Results: Eleven sarcoidosis patients without receiving any therapy had positive 18F-FDG coincidence images, among them 7 cases received 67Ga imaging in addition and obtained similar images as with 18F-FDG. The radiocounts of the background on the 18F-FDG images was lower yet with a better image quality when compared with 67Ga images. The X-ray films showed that the lesions were absorbed with negative 18F-FDG images in 3 cases after treatment, among them 2 cases with negative 67Ga images as well. Two cases with positive results from these 2 modalities received treatment and the subsequent X-ray examination demonstrated that the lesions were absorbed and the images from these 2 modalities changed to negative, too. Three cases with clinically diagnosed sarcoidosis got positive 18F-FDG images, among them 2 cases also received 67Ga imaging and had positive results, too; the image quality showed that the 18F-FDG was better than 67Ga. The X-ray film showed that the pulmonary hilar lymphnodes shrank in 1 patient after treatment but the images of these 2 modalities remained positive. Conclusion: The study shows that 18F-FDG is superior to 67Ga in the diagnosis and therapeutic monitoring of sarcoidosis