Integrated ¹⁸F-PSMA-1007 PET/MR Combined With Diffusion-Relaxation Correlation Spectrum Imaging for Preoperative Prediction of Postoperative Adverse Pathology and High ISUP Grade in Prostate Cancer

This single-center retrospective observational study investigates the preoperative risk-stratification value of integrated ¹⁸F-PSMA-1007 PET/MR combined with diffusion-relaxation correlation spectrum imaging (DR-CSI) in patients with histologically confirmed prostate cancer who subsequently underwent radical prostatectomy.

Eligible patients underwent both preoperative ¹⁸F-PSMA-1007 PET/CT and integrated PET/MR, including conventional magnetic resonance imaging and DR-CSI. Quantitative PET parameters, conventional MRI parameters, PI-RADS assessment, and DR-CSI-derived microstructural parameters are evaluated together with available preoperative clinical information. Postoperative whole-gland pathological findings serve as the reference standard.

The study compares the predictive performance of different preoperative information strategies, including clinical variables, PET/CT imaging, PET/MR imaging, and PET/MR supplemented with DR-CSI. Particular attention is given to whether DR-CSI provides complementary microstructural information beyond conventional PET/MR and whether the integrated imaging model can approach the predictive performance of a clinical model for high postoperative ISUP grade.

Model performance is assessed using internally validated prediction methods with repeated nested cross-validation and out-of-fold predictions. Discrimination, prediction error, calibration, and decision-curve characteristics are evaluated. Because this is an exploratory single-center study without external validation, comparisons between imaging strategies are interpreted as internal exploratory evidence rather than definitive proof of clinical superiority or equivalence.

Primary outcomes

• Postoperative adverse pathology and its definition [At radical prostatectomy, within approximately 1 month after preoperative imaging]: Postoperative adverse pathology was defined as the presence of at least one of the following findings on radical prostatectomy histopathology: extraprostatic extension (EPE), seminal vesicle invasion (SVI), or positive surgical margin (PSM). Patients without any of these findings were classified as adverse pathology-negative. Lymph node involvement was not included in the composite endpoint because nodal pathological assessment was not uniformly available.

Secondary outcomes

• Postoperative ISUP Grade ≥4 [Within approximately 1 month after preoperative imaging, based on histopathological assessment of the radical prostatectomy specimen.]: Postoperative ISUP grade was determined from the histopathological assessment of the radical prostatectomy specimen according to the International Society of Urological Pathology (ISUP) Grade Group system. Patients with postoperative ISUP Grade Group 4 or 5 were classified as having high-grade disease (ISUP ≥4), whereas those with Grade Group 1-3 were classified as ISUP <4.

Sex: Male, ages: 18 Years to any

Inclusion Criteria:

* Adult patients aged >30 years.
* Newly diagnosed, biopsy-confirmed prostate cancer with planned radical prostatectomy.
* Underwent both 18F-PSMA-1007 PET/MRI and PET/CT examinations.
* Availability of pathological results from our institution or another hospital obtained within 3 months of the imaging examination.

Exclusion Criteria:

* Previous surgical treatment or hormonal therapy for prostate cancer.
* Diagnosis of another malignancy within the preceding 1 year or ongoing treatment for another malignancy.