The results of this study show that physicians 1 and 2 have high inter- and intra-observer consistency, which is consistent with previous research results [10, 11]. This finding confirms that both physicians strictly followed the delineation process, effectively avoiding potential selection bias and errors due to software operation, measurement techniques, and diagnostic experience, providing a solid foundation for the reliability of subsequent studies. The high consistency results emphasize the repeatability of our method, which is crucial for reducing variability in medical practice and improving diagnostic accuracy. In addition, this high degree of consistency also indicates the universality of our nomogram model across physicians, providing the possibility for its widespread application in different clinical settings.
Through univariate analysis, feature selection by LASSO regression, and univariate and multivariate Logistic regression analysis, this study successfully identified ADC_CoeffOfVar and ADC_entropy as key parameters for predicting CSPCa. The nomogram model constructed based on these parameters showed excellent diagnostic performance in both the training set (AUC = 0.844) and the internal validation set (AUC = 0.765), confirming its effectiveness in differentiating CSPCa from non-CSPCa. The high diagnostic efficacy of this model makes it a powerful tool for personalized screening of CSPCa, helping to avoid unnecessary biopsies and overtreatment for patients with non-CSPCa.
In clinical practice, prostate biopsy not only may lead to complications such as bleeding but also may result in repeated biopsies due to inaccurate targeting, increasing the physical and economic burden on patients [12]. Therefore, reducing unnecessary biopsies is highly attractive to both patients and clinicians. The nomogram model developed in this study provides an intuitive and concise method for assessing the necessity of biopsy, which is particularly important for the majority of patients who lack medical background knowledge.
DWI, as a commonly used functional imaging sequence for diagnosing prostate cancer, is based on the Brownian motion and diffusion attenuation of water molecules, reflecting microstructural changes in living tissues. The ADC map, calculated from two DWI images with different b values, provides richer pathophysiological information, showing higher reliability and stability [13]. Numerous studies [14–16] have confirmed that features extracted from ADC images have high accuracy in predicting PCa. For example, a study by Shaish et al. [17] showed that the accuracy of ADC image features in predicting PCa was as high as 97.39%. Although the accuracy of predicting CSPCa in this study was 77.8%, slightly lower than the aforementioned study, considering that this study only focused on CSPCa and included some patients with clinically insignificant prostate cancer with a Gleason score of 3 + 3, this difference is explainable.
With the rapid development of computer technology and artificial intelligence, radiomics has shown great potential and value in the diagnosis, differential diagnosis, treatment, and prognosis assessment of PCa. Many studies at home and abroad have developed various models for predicting CSPCa, including radiomics models, clinical parameter models, PI-RADS v2.1 models, and their combined models, all with high AUC values (all over 0.8). For example, Lu et al. [18] established models for predicting PCa and CSPCa by combining PSA and its derived indicators with PI-RADS v2, with AUC values of 0.889 and 0.925, respectively. Li et al. [19] combined radiomics features with PI-RADS v2.1, obtaining AUC values of 0.989 for the training set and 0.931 for the validation set. Xu et al. [20] showed that the radiomics model was superior to the clinical parameter model in diagnostic efficacy (AUC = 0.92 vs. 0.73, P < 0.05). Woznicki et al. [21] found that the combined model of radiomics, PI-RADS, and clinical parameters was more effective in diagnosing CSPCa and CIPCa than the PI-RADS model alone (AUC = 0.844 vs 0.688). Zhang et al. [22] developed a combined model of radiomics features and ADC values, which also showed high AUC values in distinguishing CSPCa from CIPCa (training set, internal validation set, and external validation set AUC values were 0.95, 0.93, and 0.84, respectively). The results of this study show that the AUC values of the nomogram model constructed with features extracted from ADC images were 0.844 for the training set and 0.765 for the internal validation set, higher than the AUC value of the standalone clinical parameter model, and similar to the AUC of other combined models, indicating that the diagnostic efficacy of the nomogram model constructed with ADC histogram features is high, with good discrimination ability for CSPCa, and can be used in the decision-making of prostate biopsy. For example, a 60-year-old male patient with PSA above the normal range (> 4ng/mL) was diagnosed with suspected prostate cancer by a doctor, who recommended a prostate biopsy. Before the biopsy, a prostate MRI examination was performed, and features were extracted from the ADC histogram. Assuming case 1: the prostate ADC_CoeffOfVar is 900×10 − 3 mm2/s; ADC_entropy is 4000×10 − 3 mm2/s, the risk of diagnosing CSPCa is 70%, and the patient may choose a prostate biopsy; assuming case 2: the prostate ADC_CoeffOfVar is 400×10 − 3 mm2/s, ADC_entropy is 2000×10 − 3 mm2/s, the risk of diagnosing CSPCa is less than 5%, and monitoring treatment may be chosen. Therefore, this nomogram model can compare the image and ADC value differences between two patients with similar clinical characteristics and biopsy/monitoring outcomes, thereby stratifying the risks for two clinically indistinguishable patients.
Limitations
This study is a single-center, retrospective study with a relatively small sample size and lacks external validation. Multi-center data validation is needed in the future; the lesions were not anatomically divided (transition zone, peripheral zone), and whether there are differences in lesions from different divisions needs to be verified; ROI delineation is based on manual operation, which may introduce bias, and semi-automatic or automatic ROI delineation may be used to verify the results in the future; part of the pathology in this study comes from prostate biopsies, which may not be consistent with the final surgical pathology results.