Improved [68Ga]Ga-PSMA-11 image qualities reconstructed by total variation regularized expectation maximization on total-body PET/CT

Lianghua Li; Ruohua Chen; Jun Wen; Xuefei Yang; Debin Hu; Hongyan Sun; Qi Ge; Yee Ling Ng; Yun Zhou; Liangrong Wan; Yumei Chen; Weijun Wei; Jianjun Liu

doi:10.21037/qims-22-1341

Improved [⁶⁸Ga]Ga-PSMA-11 image qualities reconstructed by total variation regularized expectation maximization on total-body PET/CT

Quant Imaging Med Surg. 2023 Aug 1;13(8):5230-5241. doi: 10.21037/qims-22-1341. Epub 2023 Jul 11.

Authors

Lianghua Li^#¹, Ruohua Chen^#¹, Jun Wen¹, Xuefei Yang², Debin Hu², Hongyan Sun², Qi Ge², Yee Ling Ng², Yun Zhou², Liangrong Wan¹, Yumei Chen¹, Weijun Wei¹, Jianjun Liu¹

Affiliations

¹ Department of Nuclear Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
² Central Research Institute, United Imaging Healthcare Group Co., Ltd, Shanghai, China.

^# Contributed equally.

Abstract

Background: Total variation regularized expectation maximization (TVREM) reconstruction algorithm on the image quality of gallium (⁶⁸GA) prostate-specific membrane antigen-11 ([⁶⁸Ga]Ga-PSMA-11) total-body positron emission tomography/computed tomography (PET/CT).

Methods: Images of a phantom with small hot sphere inserts and the total-body PET/CT scans of 51 prostate cancer patients undergoing [⁶⁸Ga]Ga-PSMA-11 were reconstructed using TVREM with 5 different penalization factors between 0.09 and 0.45 and for 20-, 40-, 60-, 120-, and 300-second acquisition, respectively. As a comparison, the same data were also reconstructed using the ordered subset expectation maximization (OSEM) with 3 iterations, 20 subsets, and 300 second acquisition. The contrast recovery coefficients (CRC) and background variability (BV) of the phantom, the tumor-to-background ratios (TBR), the contrast recovery (CR) ratio, the image noise of the liver, and maximum standard uptake value (SUV_max) of the lesions were calculated to evaluate the image quality. The clinical performance of the images was evaluated by 2 radiologists with a 5-point scale (1-poor, 5-excellent).

Results: The TVREM reconstructions groups fwith 120 second acquisition and the penalization of 0.27 to 0.45 showed the best performance in terms of CR, TBR, image noise, and the gain of SUV_max compared to that obtained in the OSEM 300 second group. Even the image noise of the TVREM 120 second group with a penalization factor of 0.27 and 0.36 was comparable to the OSEM 300 second group; the lesions' SUV_max increased by 28% whereas the image noise decreased by 5% and 14%, respectively. The TVREM 120 second group with a penalization factor of 0.36 (5.00±0.00) had the highest qualitative score that equaled OSEM and TVREM for the 300 second (P>0.05) group.

Conclusions: Our study has shown the potential of the TVREM reconstruction algorithm with optimized penalization factors to achieve comparable [⁶⁸Ga]Ga-PSMA-11 total-body PET/CT image quality with a shorter acquisition time, compared with the conventional OSEM reconstruction algorithm.

Keywords: Image quality; prostate-specific membrane antigen; reconstruction algorithm; total-body positron emission tomography/computed tomography (PET/CT); uEXPLORER.