Malignant pleural effusion (MPE) characterized with 11C-Methionine PET/CT before and after talc pleurodesis: interim evaluation of a prospective clinical trial

Background

Malignant pleural effusion (MPE) is one the most frequent signs of mesothelioma presentation. 18F-FDG PET/CT has proved to be useful in detecting pleural lesions, although unreliable results have been reported in patients receiving talc pleurodesis due to induced inflammatory reaction. In this study we aimed to define the role of 11C-methionine PET/CT in the characterization of MPE before and after talc pleurodesis.

Methods

From September 2014 to February 2016 30 consecutive patients referred to our Institution for MPE were prospectively enrolled. Patients were evaluated at baseline and after pleurodesis with two consecutive PET investigations: 11C-methionine (experimental) and 18F-FDG (standard). Semi-quantitative PET parameters were defined for both examinations: i.e. SUVmax, SUVmean, metabolic tumor volume (MTV) and metabolic tumor burden (MTB = MTVxSUVmean), and statistically compared to pathological findings at videothoracoscopy.

Results

The interim analysis was completed in 15 patients (M:F = 13:2; mean age 73 years) affected by malignant mesothelioma (12 epithelioid, 3 non-epithelioid). All tumors showed increased uptake of 11C-methionine at baseline: median SUVmax, SUVmean, MTV and MTB were 4.7 (range 3-10.1), 2.8 (range 1.5-4.6), 19.5 (range 0.9-464.3) and 45.2 (range 2-2052.2), respectively. MTV and MTB were significantly higher in non-epithelioid tumors compared to other histotype (p = 0.022 and 0.03, respectively). For 11C-methionine PET the median percentage of variation before and after talc pleurodesis was 12.8 for SUVmax (%ΔSUV) and 29.9 for MTB (%ΔMTB). Compared to 18F-FDG, the percentage of variation for MTB resulted significantly lower for 11C-methionine (p 

Conclusions

11C-methionine PET/CT appears able to characterise malignant pleural effusion. This preliminary analyses shows that it might be less influenced by inflammatory reaction related to talc pleurodesis compared to 18F-FDG.

Clinical trial identification

NCT02519049

Legal entity responsible for the study

IRCCS Istituto Clinico Humanitas - Humanitas Mirasole SPA

Funding

IRCCS Istituto Clinico Humanitas - Humanitas Mirasole SPA

Disclosure

All authors have declared no conflicts of interest.