Utility of Amino Acid PET in the Differential Diagnosis of Recurrent Brain Metastases and Treatment-Related Changes: A Meta-analysis

Amino acid PET is an established method to assist differential diagno-sis of therapy-related changes versus recurrence in gliomas. How-ever, its diagnostic value in brain metastases is yet to be determined. The goal of this study was to summarize evidence on the diagnostic utility of amino acid PET in recurrent brain metastases. Methods: The medical databases MEDLINE, EMBASE , the Cochrane Library were screened for English-language studies with at least 10 patients who had undergone first-line treatment including radiotherapy , in whom a final diagnosis had been determined by histologic examina-tion or imaging and clinical follow-up. Pooled estimates with 95% CIs were calculated. Heterogeneity was assessed using I2 statistics. Results: Following the above criteria, 12 studies with the tracers methyl-[11C]-methionine (n = 6), O-(2-[18F]fluoroethyl)-L-tyrosine (n = 3), methyl-[11C]-methionine and O-(2-[18F]fluoroethyl)-L-tyrosine (n = 1), and 6-[18F]fluoro-L-dopa (n = 2), with a total of 547 lesions in 397 patients, were included. Pooled sensitivity and specificity were 82% (95% CI, 76-86) and 84% (95% CI, 79-88), respectively. Pooled positive and negative predictive values were 84% (95% CI, 77-90) and 83% (95% CI, 77-88), respectively. Positive and negative likelihood ratios, and diagnostic odds ratio were 3.8 (95% CI 3.0-4.8), 0.3 (95% CI 0.2-0.3), and 16.7 (95% CI 10.8-25.9), respectively. Heterogeneity was overall low. Conclusion: The present meta-analysis indicates a good accuracy of amino acid PET in the differential diagnosis of recurrent brain metastases. In particular, specificity of 84% suggests that amino acid PET may reduce the number of invasive procedures and overtreat-ment in patients with treatment-related changes. This study provides class IIa evidence on the utility of amino acid PET in the differential diag-nosis of recurrent brain metastases.

Automated summary

This study aimed to summarize the diagnostic utility of amino acid PET in recurrent brain metastases. The analysis of 12 studies with a total of 547 lesions in 397 patients showed that amino acid PET had good accuracy in the differential diagnosis of recurrent brain metastases, with a specificity of 84%, suggesting it can reduce the need for invasive procedures and overtreatment.