Positron Range Corrections and Denoising Techniques for Gallium-68 PET Imaging: A Literature Review

Gallium-68 (Ga-68) is characterized by relatively high positron energy compared to Fluorine-18 (F-18), causing substantial image quality degradation. Furthermore, the presence of statistical noise can further degrade image quality. The aim of this literature review is to identify the recently developed positron range correction techniques for Ga-68, as well as noise reduction methods to enhance the image quality of low count Ga-68 PET imaging. The search engines PubMed and Scopus were employed, and we limited our research to published results from January 2010 until 1 August 2022. Positron range correction was achieved by using either deblurring or deep learning approaches. The proposed techniques improved the image quality and, in some cases, achieved an image quality comparable to F-18 PET. However, none of these techniques was validated in clinical studies. PET denoising for Ga-68-labeled radiotracers was reported using either reconstruction-based techniques or deep learning approaches. It was demonstrated that both approaches can substantially enhance the image quality by reducing the noise levels of low count Ga-68 PET imaging. The combination of Ga-68-specific positron range correction techniques and image denoising approaches may enable the application of low-count, high-quality Ga-68 PET imaging in a clinical setting.