The review answered a clear question. Inclusion criteria were defined. The literature search was limited and restriction of the review to published studies in English raised the possibility of language and publication biases. Details of the review process were not reported and so it was not possible to determine whether appropriate steps were taken to minimise bias and errors. Study quality was not formally assessed and so the risk of bias in the included studies was unclear. Very few details on the included studies were reported, which made it difficult to determine the generalisability of the review findings. The methods used to pool data appeared appropriate, although it appeared that the authors did not use the most statistically robust bivariate model and heterogeneity was not fully investigated. It may also have been helpful to have pooled data separately for PET and PET/CT.
The authors' conclusions were supported by the data, but should be interpreted with caution due to the small heterogeneous studies of unclear quality included in the review and the possibility of missing studies.