BERKELEY, CA (UroToday.com) - In this meta-analysis, we evaluated the diagnostic value of choline PET/CT, SPECT, MRI, and BS for detecting bone metastases from prostate cancer. The following were some additional evaluations on study design, trial limitation or other concepts not fully expressed in the abstract.
Choline, as an essential component of the phospholipids, is part of the cell membrane and the increase in cell proliferation as well as the activity of the enzyme choline kinase in prostate cancer cells is associated with an increase in choline as an indispensable component.[1] With regard to “choline,” we included both 11C-choline analogues and 18F-choline analogues, which might be a conflicting inclusion criterion. From a technical point of view, the synthesis process and imaging protocol were really different, while in fact there was no significant difference from a clinical point of view. The sensitivity and specificity of these two tracers were similar. The most remarkable difference between 11C-choline and 18F-choline is the difference in their half-lives (20 min for 11C-choline vs. 110 min for 18F- choline). In addition, urinary excretion of 18F-choline is comparatively higher than that of 11C-choline. Advantages and limitations of 18F-FDG and choline PET tracers are summarized in the table.[2]
In total, 16 articles consisting of 27 studies were included in the analysis. It is necessary to analyze data both on a per patient basis and on a per lesion basis. However, due to limited information and small sample size, we could not perform subgroup analysis for PET/CT, SPECT, and MRI -- as well as not evaluate the publication bias. In addition, there was no accepted gold standard, which may be a universal drawback to all studies for detecting bone metastases from various tumors with different modalities. In this study we had to use “comprehensive diagnosis of other imaging techniques, or clinical and imaging follow-up for at least 6 months” as the suboptimal reference standard, while histopathological or surgery results could not be obtained for ethical reasons. As a result, for per patient, both sensitivity and specificity of MRI and BS were more highly heterogeneous compared to those of choline PET/CT. I2 index of choline PET/CT was 0.0 % for sensitivity, 2.8 % for specificity, of which sensitivity and specificity values were found to be homogeneous. However, for per lesion, both sensitivity and specificity value for choline PET/CT, bone SPECT, and BS were highly heterogeneous.
This present meta-analysis showed that MRI was found to be better than choline PET/CT and BS on a per patient basis, though choline PET/CT had the highest specificity. On a per lesion analysis, choline PET/CT with the highest DOR and Q* was better than bone SPECT and BS for detecting bone metastases from prostate cancer. However, due to the huge heterogeneity, higher-quality studies and more included articles with a large sample size are required for more available research in the future.
References:
- Richter JA, Rodríguez M, Rioja J, et al. Dual tracer 11C-choline and FDG-PET in the diagnosis of biochemical prostate cancer relapse after radical treatment. Mol Imaging Biol. 2010;12:210–7.
- Evangelista L, Guttilla A, Zattoni F, Muzzio PC, Zattoni F. Utility of choline positron emission tomography/computed tomography for lymph node involvement identification in intermediate- to high-risk prostate cancer: a systematic literature review and meta-analysis. Eur Urol. 2013 Jun;63:1040-8.
Written by:
Guoua Shen and Zhiyun Jia as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
Department of Nuclear Medicine, West China Hospital of Sichuan University, No. 37 Guo Xue Xiang, Chengdu, Sichuan, 610041, People’s Republic of China