Bagheri Hamed, Mahdavi Seied Rabi, Geramifar Parham, Neshasteh-Riz Ali, Sajadi-Rad Masoumeh, Dadgar Habibollah, Arabi Hossein, Zaidi Habib
Radiation Biology Research Center, Iran University of Medical Sciences (IUMS), Tehran, Iran.
Department of Medical Physics, Radiation Biology Research Center, Iran University of Medical Sciences (IUMS), Tehran, Iran.
Adv Radiat Oncol. 2025 Jun 9;10(8):101821. doi: 10.1016/j.adro.2025.101821. eCollection 2025 Aug.
Magnetic resonance imaging (MRI) with multiparametric assessment is a cornerstone in radiation therapy planning for primary prostate cancer (PCa), offering the potential for focal dose escalation to dominant intraprostatic lesions to enhance PCa management. The prostate-specific membrane antigen (PSMA), which is frequently overexpressed in PCa, has led to the development of Ga-labeled PSMA inhibitors for positron emission tomography (PET)/computed tomography (CT), showing promising results in PCa detection. This study aimed to conduct a comparative analysis of Ga-PSMA PET/CT and multiparametric MRI (mpMRI) in delineating the gross tumor volume (GTV) in PCa.
A retrospective analysis was performed on 25 PCa patients who underwent Ga-PSMA PET/CT and mpMRI at 2 distinct centers. The GTVs were delineated on MRI (GTV-MRI) by 2 nuclear medicine physicians and 1 radiation oncologist independently, while the GTVs based on PET/CT (GTV-PET) were outlined by 2 nuclear medicine physicians. The laterality (left, right, and bilateral) prostate lobes on mpMRI and PET/CT was assessed. To account for registration uncertainties, both GTV-PET and GTV-MRI were expanded isotropically by 5 mm to form the planning target volume (PTV), and the overlap between specific PTVs and their corresponding GTVs was quantified.
The average ± SD GTV-MRI and GTV-PET were 5.468 ± 11.6 cm³ and 11.136 ± 14.3 cm³, respectively, with the GTV-PET being significantly larger than the GTV-MRI ( = .003). GTV-MRI exhibited an intersection with GTV-PET of 3.5 ± 6.0 cm³. The PTV derived from PSMA PET/CT encompassed 62% ± 27% of the GTV-MRI, with 44.4% of patients having the PTV covering 100% of the GTV-MRI. Conversely, the PTV based on GTV-MRI covered 50% ± 31% (mean ± SD) of the GTV-PET.
Ga-PSMA PET/CT and mpMRI demonstrated consistent outcomes in 47% of patients (40%-54% of lesions). Notably, the GTV-PET was larger than the GTV-MRI, indicating a potential role for Ga-PSMA PET/CT in radiation therapy planning for targeted radiation delivery to PCa.
多参数评估的磁共振成像（MRI）是原发性前列腺癌（PCa）放射治疗计划的基石，为对前列腺内主要病灶进行局部剂量递增以加强PCa管理提供了可能。前列腺特异性膜抗原（PSMA）在PCa中常过度表达，促使了用于正电子发射断层扫描（PET）/计算机断层扫描（CT）的镓标记PSMA抑制剂的研发，在PCa检测中显示出有前景的结果。本研究旨在对镓标记PSMA PET/CT和多参数MRI（mpMRI）在勾画PCa大体肿瘤体积（GTV）方面进行对比分析。
对25例在2个不同中心接受镓标记PSMA PET/CT和mpMRI检查的PCa患者进行回顾性分析。2名核医学医师和1名放射肿瘤学家独立在MRI上勾画GTV（GTV-MRI），而2名核医学医师勾画基于PET/CT的GTV（GTV-PET）。评估mpMRI和PET/CT上前列腺叶的侧别（左、右和双侧）。为考虑配准不确定性，GTV-PET和GTV-MRI均各向同性地扩大5 mm以形成计划靶体积（PTV），并对特定PTV与其相应GTV之间的重叠进行量化。
GTV-MRI的平均±标准差为5.468±11.6 cm³，GTV-PET为11.136±14.3 cm³，GTV-PET显著大于GTV-MRI（P = 0.003）。GTV-MRI与GTV-PET的交集为3.5±6.0 cm³。源自PSMA PET/CT的PTV包含GTV-MRI的62%±27%，44.4%的患者其PTV覆盖GTV-MRI的100%。相反，基于GTV-MRI的PTV覆盖GTV-PET的50%±31%（平均±标准差）。
镓标记PSMA PET/CT和mpMRI在47%的患者（40%-至54%的病灶）中显示出一致的结果。值得注意的是，GTV-PET大于GTV-MRI，表明镓标记PSMA PET/CT在PCa靶向放射治疗计划中可能发挥作用。
