Pilot study comparing dominant intraprostatic lesion volume using Ga-68 prostate-specific membrane antigen PET-computed tomography and multiparametric MRI
Related Experiment Video
Updated: Dec 8, 2025
A Cognitive Fusion-guided Prostate Biopsy Using Multiparametric Magnetic Resonance Imaging and Transrectal Ultrasound
Published on: March 21, 2025
Ajay Sasidharan1, Vedang Murthy1, Aravintho Natarajan2
1Departments of Radiation Oncology.
Purpose:
The standard imaging used for delineation of dominant intraprostatic lesion (DIL) is multiparametric MRI (mpMRI). The use of biologic imaging such as Ga-68 prostate-specific membrane antigen (PSMA) PET-computed tomography (PET-CT) for this purpose is being explored in view of increased sensitivity of this modality and the associated ease of delineation.
Materials And Methods:
The primary objective of the study was to compare the autogenerated volumes of the DIL in Ga-68 PSMA PET-CT with the standard volume delineated in mpMRI. Twenty patients with biopsy-proven untreated prostatic adenocarcinoma were included. Multiple percentages of the maximum standardized uptake value (%SUVmax) were used to autogenerate DIL volumes in Ga-68 PSMA PET-CT and these volumes were numerically matched with the consensus DIL volume in mpMRI. PSMA tumor volume (PSMA-TV) and total lesion PSMA (TL-PSMA) were also calculated for each lesion.
Results:
Median volume of DIL in mpMRI was 4 cm (interquartile range, IQR = 2.5-7.6 cm). The IQR for interobserver variability was 0.5-2.5 cm. Median SUVmax of the DIL was 14.1 (IQR = 10.2-22.3). Median %SUVmax corresponding to mpMRI volume was 41% of SUVmax (IQR = 34-55%). There was a strong negative correlation between MRI volume and %SUVmax (r = -0.829, P < 0.001). There was a significant correlation between TL-PSMA and prostate-specific antigen (r = 0.609, P = 0.004).
Conclusions:
The median DIL volume was 4 cm and median %SUVmax corresponding to MR volume of DIL was 41%. A strong inverse relationship is found between mpMRI-defined DIL volume and the %SUVmax which generates similar volume in Ga-68 PSMA PET-CT. TL-PSMA could be a quantitative biomarker for tumor load and prognosis.
Insights
Gallium-68 prostate-specific membrane antigen (PSMA) PET-CT shows promise for delineating dominant intraprostatic lesions (DILs). A strong inverse relationship exists between multiparametric MRI (mpMRI) volume and %SUVmax, suggesting PSMA PET-CT can provide comparable DIL volume estimations. Total lesion PSMA (TL-PSMA) may serve as a prognostic biomarker.
Area of Science:
- Nuclear medicine imaging
- Radiopharmaceuticals
- Prostate cancer diagnostics
Background:
- Multiparametric MRI (mpMRI) is the standard for delineating dominant intraprostatic lesions (DILs).
- Gallium-68 prostate-specific membrane antigen (PSMA) PET-CT is being explored for DIL delineation due to its high sensitivity and ease of use.
Purpose of the Study:
- To compare autogenerated DIL volumes from Ga-68 PSMA PET-CT with standard mpMRI-delineated volumes.
- To evaluate the correlation between imaging metrics and clinical parameters.
Main Methods:
- Twenty patients with biopsy-proven prostate adenocarcinoma were included.
- DIL volumes were autogenerated in Ga-68 PSMA PET-CT using various %SUVmax thresholds.
- Volumes were compared to consensus DIL volumes from mpMRI.
- PSMA tumor volume (PSMA-TV) and total lesion PSMA (TL-PSMA) were calculated.
Main Results:
- Median DIL volume in mpMRI was 4 cm³.
- Median %SUVmax corresponding to mpMRI volume was 41%.
- A strong negative correlation (r = -0.829, P < 0.001) was observed between mpMRI volume and %SUVmax.
- A significant correlation (r = 0.609, P = 0.004) was found between TL-PSMA and prostate-specific antigen.
Conclusions:
- A strong inverse relationship exists between mpMRI-defined DIL volume and the %SUVmax that yields similar volumes on Ga-68 PSMA PET-CT.
- TL-PSMA may function as a quantitative biomarker for tumor burden and prognosis.
