Multi-parameter spectral computed tomography for the prognosis evaluation of prostate cancer bone metastasis: a retrospective study.

Background: Prostate cancer (PCa) is one of the most prevalent malignancies in men, and the skeleton is a common site of distant metastasis. Bone metastases can lead to skeletal-related events, reduced quality of life, and increased mortality. Accurate imaging evaluation during post-treatment follow-up is crucial for timely intervention and optimal patient management. Dual-energy computed tomography (DECT) multi-parameter imaging has shown potential in characterizing bone lesions, whereas whole-body bone scintigraphy (WBS) remains widely applied in clinical practice. This study was designed to compare the diagnostic performance of DECT and WBS in detecting prostate cancer bone metastases (PCa-BMs) during post-treatment follow-up. Methods: PCa-BM is a common manifestation of advanced disease and has a substantial impact on patient prognosis. This retrospective study, conducted between November 2020 and October 2023, enrolled consecutive patients with confirmed PCa-BM to compare the diagnostic performance of DECT and WBS during post-treatment follow-up. DECT images were independently evaluated by two blinded radiologists, each specializing in genitourinary imaging and possessing three years of experience. In instances of disagreement, consensus was achieved through arbitration by a senior radiologist with 15 years of experience. The WBS images were independently interpreted by a nuclear medicine physician with 15 years of experience in nuclear medicine imaging, with the evaluation conducted separately from the DECT team. The Pearson Chi-squared test was employed to compare DECT multiparametric data with WBS results. The diagnostic performance of DECT multiparametric images, both independently and in conjunction with prostate-specific antigen (PSA) levels, was compared against clinical diagnosis. Key metrics assessed comprised accuracy, specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV). Receiver operating characteristic (ROC) curve analysis was performed using statistical software. Results: Data from a total of 46 patients with PCa-BM, comprising 206 metastatic vertebrae, were analyzed. Clinical assessment identified 29 patients (132 lesions) with an effective therapeutic response and 17 patients (74 lesions) with disease progression. DECT analysis demonstrated a significant correlation between venous-phase hydroxyapatite (HAP)-water values and uptake on WBS (P=0.019). In contrast, other keV (kiloelectron volt)-based computed tomography (CT) values and water-HAP parameters did not show significant associations (P>0.05). Compared to clinical diagnosis, DECT parameters from varying keV and water-HAP images exhibited limited diagnostic performance, with area under the curve (AUC) values ranging from 0.425 to 0.568, and with generally low sensitivity, specificity, PPV, and NPV. Notably, integrating DECT parameters with serum PSA levels significantly improved diagnostic sensitivity (up to 93.94%), PPV (up to 71.60%), NPV (up to 74.19%), and AUC (ranging from 0.584 to 0.635), although specificity remained low (24.32-35.14%). Conclusions: DECT-derived water-HAP images demonstrate potential value in evaluating PCa-BM during post-treatment follow-up, particularly when integrated with serum PSA measurements.