Impact of Region-of-Interest Delineation on Stability and Reproducibility of Liver SNR Measurements in 68 Ga-PSMA PET/CT

Masoomeh Fooladi; Sahar Rezaei; Farahnaz Aghahosseini; Yalda Salehi; Nima Kasraie; Peyman Sheikhzadeh

doi:10.1055/s-0043-1768446

Impact of Region-of-Interest Delineation on Stability and Reproducibility of Liver SNR Measurements in ⁶⁸ Ga-PSMA PET/CT

World J Nucl Med. 2023 May 16;22(2):124-129. doi: 10.1055/s-0043-1768446. eCollection 2023 Jun.

Authors

Masoomeh Fooladi¹, Sahar Rezaei^{2

3}, Farahnaz Aghahosseini⁴, Yalda Salehi⁴, Nima Kasraie⁵, Peyman Sheikhzadeh^{1

4}

Affiliations

¹ Department of Medical Physics and Biomedical Engineering, Tehran University of Medical Sciences, Tehran, Iran.
² Department of Radiology, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
³ Clinical Research Development Unit, Imam Reza General Hospital, Tabriz University of Medical Sciences, Tabriz, Iran.
⁴ Department of Nuclear Medicine, Imam Khomeini Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran.
⁵ Department of Radiology, UT Southwestern Medical Center, Dallas, Texas, United States.

Abstract

Objective This study aims to assess the impact of various regions of interest (ROIs) and volumes of interest (VOIs) delineations on the reproducibility of liver signal-to-noise-ratio (SNRliver) measurements, as well as to find the most reproducible way to estimate it in gallium-68 positron emission tomography ( ⁶⁸ Ga-PET) imaging. We also investigated the SNRliver-weight relationship for these ROIs and VOIs delineations. Methods A cohort of 40 patients (40 males; mean weight: 76.5 kg [58-115 kg]) with prostate cancer were included. ⁶⁸ Ga-PET/CT imaging (mean injected activity: 91.4 MBq [51.2 MBq to 134.1 MBq] was performed on a 5-ring bismuth germanium oxide-based Discovery IQ PET/CT using ordered subset expectation maximization image reconstruction algorithm. Afterward, circular ROIs and spherical VOIs with two different diameters of 30 and 40 mm were drawn on the right lobe of the livers. The performance of the various defined regions was evaluated by the average standardized uptake value (SUV _mean ), standard deviation (SD) of the SUV (SUV _SD ), SNR _liver , and SD of the SNR _liver metrics. Results There were no significant differences in SUV _mean among the various ROIs and VOIs ( p > 0.05). On the other hand, the lower SUV _SD was obtained by spherical VOI with diameter of 30 mm. The largest SNR _liver was obtained by ROI (30 mm). The SD of SNR _liver with ROI (30 mm) was also the largest, while the lowest SD of SNR _liver was observed for VOI (40 mm). There is a higher correlation coefficient between the patient-dependent parameter of weight and the image quality parameter of SNRliver for both VOI (30 mm) and VOI (40 mm) compared to the ROIs. Conclusion Our results indicate that SNR _liver measurements are affected by the size and shape of the respective ROIs and VOIs. The spherical VOI with a 40 mm diameter leads to more stable and reproducible SNR measurement in the liver.

Keywords: 68 Ga-PET; image quality; quality control; region of interest; signal-to-noise ratio.

The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution License, permitting unrestricted use, distribution, and reproduction so long as the original work is properly cited. ( https://creativecommons.org/licenses/by/4.0/ ).

Grants and funding

Funding This work was supported under grant number 55707, Tehran University of Medical Sciences.