The Accuracy of Quantitative Lutetium-177 Single Photon Emission Computed Tomography Imaging and the Role for Partial-Volume Corrections in Clinical Practice: A Systematic Review

BackgroundAccurate quantification of lutetium-177 (177Lu) radioactivity in SPECT/CT imaging is essential for a further development of 177Lu-based peptide receptor radionuclide therapy (PRRT) for neuroendocrine tumours and metastatic prostate cancer. PurposeThis review provides an overview on the accuracy of quantitative 177Lu SPECT/CT imaging, identifies methods for an improved accuracy when imaging small volumes subject to partial-volume effects (PVEs), and assesses the role for partial-volume corrections (PVCs) in clinical practice. MethodsA systematic review was conducted according to PRISMA guidelines. MEDLINE, EMBASE, and Web of Science databases were searched with no language restrictions. Original studies explicitly reporting on the accuracy of 177Lu activity quantifications in physical SPECT/CT measurements were included. ResultsThe literature search identified 616 records, of which 46 studies were included for analysis. Percentage errors of quantifications were found to constitute a large range (-102% to 285%). The recovery of 177Lu activity from small volumes is inherently limited by PVEs. The application of PVCs has led to improvements in the accuracy and precision of quantifications on small volumes in phantom imaging. ConclusionThe accuracy of 177Lu activity quantifications in SPECT/CT imaging is subject to large variability and will be degraded by PVEs when imaging small volumes. The data suggests that the implementation of standardised procedures and PVCs may lead to an improved accuracy and precision of quantitative 177Lu SPECT/CT imaging in clinical practice, thereby allowing the further development of 177Lu-based PRRT.