Evaluation of pleural lesions after pleurodesis with OK-432 by fluorodeoxyglucose-positron emission tomography/CT

Objective This study aimed to determine changes in FDG-PET/CT after pleurodesis with OK-432 and to investigate differences in the changes between non-malignant and malignant lesions. Methods Study participants were 17 patients with a history of malignant chest disease who underwent FDG-PET/CT after pleurodesis using OK-432 and in whom pleural lesions were determined to be non-malignant ( n = 8) or malignant ( n = 9). FDG uptake (SUV max ) was counted on all pleural lesions. CT findings (CT attenuation, shape) of pleural lesions with increased FDG uptake were evaluated. Results The number of patients with increased FDG uptake in the pleura differed significantly between the non-malignant group (3/8) and malignant group (9/9) ( p < 0.01) The mean SUV max of non-malignant lesions with increased FDG uptake was 2.3 ± 0.7 vs. 6.2 ± 2.2 in malignant lesions, for a significant difference ( p < 0.01). The mean CT attenuation of lesions was 36 ± 11 HU in the non-malignant group and 34 ± 14 HU in the malignant group, a difference that was not significant ( p = 0.91). There was a significant difference in nodular and linear shapes between non-malignant and malignant lesions ( p < 0.01). All non-malignant lesions were linear. Conclusions Positive FDG uptake was shown in non-malignant pleural lesions as well as in malignant pleural lesions after pleurodesis using OK-432. Combined analysis of FDG accumulation and CT morphology is helpful to distinguish between benign and malignant lesions.