Repeated amino acid PET imaging for longitudinal monitoring of brain tumors

Purpose Amino acid PET is a useful complement to MRI in a number of clinical settings for the evaluation of brain tumors. However, amino acid PET is rarely used repeatedly over the course of the disease. We reviewed the existing literature on the use of repeated amino acid PET imaging for monitoring primary or secondary brain tumors. Methods A comprehensive literature search of articles describing the use of longitudinal amino acid PET imaging of brain tumors was performed on PubMed/MEDLINE using multiple search terms. Additional literature was retrieved from the reference lists of identified studies or based on the authors' personal knowledge and experience. Results With regard to primary tumors, two main clinical settings were identified in whom the performance of repeated amino acid PET imaging was most commonly assessed. These include the detection of malignant progression of patients with grade II or III glioma characterized according to older WHO classifications, and the early response assessment of various treatment options in glioma patients. For patients with brain metastases, only a few studies were identified using longitudinal amino acid PET for the diagnosis of post-treatment changes after stereotactic radiosurgery. The analyzed studies reported that longitudinal amino acid PET imaging frequently anticipate or even outperform the diagnostic performance provided by conventional MRI in these settings. Conclusions The available literature suggests that conventional MRI should be accompanied by longitudinal amino acid PET monitoring in these clinical settings. Nevertheless, more reliable evidence derived from larger, prospective multicenter studies is warranted.