Artificial intelligence for prostate cancer detection and risk stratification using transrectal ultrasound: a narrative review
Review Article

Artificial intelligence for prostate cancer detection and risk stratification using transrectal ultrasound: a narrative review

Qiong Zhang# ORCID logo, Chenyun Zhou#, Yang Chen ORCID logo, Yan Luo ORCID logo

Department of Medical Ultrasound, West China Hospital, Sichuan University, Chengdu, China

Contributions: (I) Conception and design: All authors; (II) Administrative support: None; (III) Provision of study materials or patients: None; (IV) Collection and assembly of data: All authors; (V) Data analysis and interpretation: None; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.

#These authors contributed equally to this work.

Correspondence to: Yan Luo, MD. Department of Medical Ultrasound, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu 610041, China. Email: yanluo@scu.edu.cn.

Background and Objective: Prostate cancer (PCa) management and outcomes are dependent on risk stratification. Indolent disease is often managed with active surveillance, whereas clinically significant PCa (CSPCa) necessitates prompt intervention due to its aggressive potential. Although transrectal ultrasound (TRUS) is central to diagnosis and biopsy guidance, its limited resolution and high interobserver variability complicate accurate risk assessment. Artificial intelligence (AI) offers a promising solution to these limitations. This review evaluates the current landscape of TRUS-based AI models for three critical objectives: PCa detection, CSPCa identification, and risk stratification.

Methods: We systematically searched the PubMed and Web of Science databases for peer-reviewed, original English-language articles published from 1999 to 2026.

Key Content and Findings: TRUS-based AI models have advanced significantly, achieving area under the curve (AUC) values of 0.78–0.96 for PCa detection and 0.85–0.90 for CSPCa identification, particularly when leveraging three-dimensional (3D) architectures or multiparametric fusion (e.g., elastography or contrast enhancement). Performance is robust for binary risk stratification (e.g., low-intermediate vs. high-risk). However, a critical gap remains: no existing AI model has successfully predicted the full spectrum of the five-tier International Society of Urological Pathology (ISUP) Grade Group (GG) stratification using TRUS imaging alone. Key barriers to clinical translation include challenges in precise lesion localization, the complexity of annotating risk-stratified labels, and the predominance of single-center retrospective datasets.

Conclusions: TRUS-based AI demonstrates high accuracy for PCa detection and CSPCa identification, particularly with 3D architectures or multiparametric fusion. However, the inability to predict the full five-tier ISUP GG stratification represents a major unmet need. Future research should prioritize standardized multicenter data collection and advanced algorithms to address localization challenges and enable precise risk stratification, thereby facilitating clinical translation.

Keywords: Prostate cancer (PCa); clinically significant prostate cancer (CSPCa); prostate cancer risk stratification; artificial intelligence (AI); transrectal ultrasound (TRUS)


Submitted Oct 29, 2025. Accepted for publication Jan 20, 2026. Published online Feb 11, 2026.

doi: 10.21037/gs-2025-aw-504


Introduction

Prostate cancer (PCa) remains a leading cause of cancer morbidity and mortality globally (1,2). Unlike many other malignant tumors that progress rapidly, early-stage clinically insignificant PCa (CISPCa) is characterized by low risk and slow progression, and is managed primarily with active surveillance rather than immediate treatment. In contrast, intermediate-to-advanced clinically significant PCa (CSPCa) carries a high risk of progression and a poor prognosis, requiring aggressive intervention (3-5). Therefore, clinical practice prioritizes identifying CSPCa and accurately stratifying PCa risk. Pathological assessment based on the Gleason score (GS) remains the gold standard for diagnosing PCa and guiding risk stratification (6). Clinically, a GS of ≥3+3 confirms PCa (6), with subsequent stratification into CSPCa (GS >3+3) and CISPCa (GS ≤3+3) based on pathological features.

PCa risk stratification relies on two primary frameworks:

  • The D’Amico risk stratification, adopted by the European Association of Urology (EAU), stratifies PCa into three categories: low-risk (GS ≤6), intermediate-risk (GS =7), and high-risk (GS ≥8) (7,8) (hereafter referred to as the “three-tier risk stratification”).
  • The Grade Group (GG) system proposed by the International Society of Urological Pathology (ISUP) (6), which refines risk stratification into five tiers: GG1 (GS 3+3), GG2 (GS 3+4), GG3 (GS 4+3), GG4 (GS 8), and GG5 (GS 9 or 10) (hereafter referred to as the “five-tier risk stratification”).

For this review, PCa was further subdivided into subgroups based on these two systems:

  • Based on the three-tier risk stratification, five subgroups were defined: low-risk (GS ≤6), intermediate-risk (GS =7), high-risk (GS ≥8), low-to-intermediate risk (GS ≤7), and intermediate-to-high risk (GS ≥7).
  • Based on the five-tier risk stratification, 11 subgroups were defined: low-risk (GG1), low-to-intermediate risk (GG2), intermediate-risk (GG3), intermediate-to-high risk (GG4), high-risk (GG5), below-intermediate risk (GG1–2), intermediate-risk and below (GG1–3), below-high risk (GG1–4), above-low risk (GG2–5), intermediate-risk and above (GG3–5), and above-intermediate risk (GG4–5).

Currently, multiparametric magnetic resonance imaging (mpMRI) serves as the reference standard for PCa detection and local staging (9). However, its widespread adoption is hindered by high costs and limited accessibility. In contrast, transrectal ultrasound (TRUS) remains the most prevalent imaging modality due to its cost-effectiveness, real-time capabilities, and integral role in biopsy guidance (3,10,11). Notwithstanding these advantages, its limited resolution and high interobserver variability impede accurate risk assessment. Integrating artificial intelligence (AI) into TRUS workflows, therefore, presents a critical opportunity to enhance diagnostic precision, offering a viable alternative to resource-intensive mpMRI and addressing an unmet need in urological practice.

To our knowledge, existing research on TRUS-based AI has primarily focused on PCa detection and diagnosis (12-15). While several studies have explored the utility of AI for CSPCa identification via TRUS, reporting area under the curve (AUC) values of 0.85–0.89 (16), its application in risk stratification remains inadequately explored. Notably, only one study has investigated AI-based prediction of three-tier risk stratification, achieving a diagnostic accuracy of 0.830 (7), and comprehensive research on AI-driven differentiation across all five ISUP GG tiers is currently lacking. This review summarizes the current status and recent advances in TRUS-based AI models for PCa diagnosis, CSPCa identification, and risk stratification. We present this article in accordance with the Narrative Review reporting checklist (available at https://gs.amegroups.com/article/view/10.21037/gs-2025-aw-504/rc).


Methods

We systematically searched the PubMed and Web of Science databases for original research articles published from 1999 to 2026, focusing on AI applications in ultrasound for PCa detection. Only peer-reviewed, English-language studies were included. The detailed search strategy, including keywords and MeSH terms, is outlined in Table 1.

Table 1

Search strategy summary

Items Specification
Date of search Initial search: January 24, 2025; final update: January 9, 2026
Databases and other sources searched PubMed, Web of Science
Search terms used A combination of “artificial intelligence”, “prostate cancer”, “clinically significant prostate cancer”, “prostate cancer risk stratification”, “transrectal ultrasound”, “Micro-ultrasound”, “Shear wave elastography”, “Computer-aided diagnosis”, or “Radiomics”
Timeframe 1999–2026
Inclusion and exclusion criteria Inclusion criteria: (I) Original research articles published in English. (II) Studies investigating or evaluating the application of ultrasound-based AI for the detection or diagnosis of PCa
Exclusion criteria: (I) Review articles, editorials, and commentaries. (II) Conference abstracts or proceedings
Selection process The authors conducted the selection independently. Each article was evaluated regarding its value and relevance to the review

AI, artificial intelligence; PCa, prostate cancer.


Discussion

Table 2 summarizes a subgroup analysis of AI-based ultrasound modalities for PCa, comparing the key technical features of distinct TRUS-based models. TRUS, centered on two/three-dimensional (2D/3D) deep learning, offers accessible data (AUC: 0.78–0.96) (16,21,22,27), broad compatibility with standard equipment, and high clinical utility; however, 2D models are vulnerable to image artifacts, whereas 3D models demand substantial computing power, necessitating lightweight optimization and small-sample expansion strategies. Temporal enhanced ultrasound (TeUS) captures dynamic features via recurrent neural networks (RNNs) or unsupervised deep neural networks, achieving an AUC >0.8 for high-grade PCa (14); yet, its reliance on specialized equipment, time-consuming sequence processing, and limited sample sizes (<160 cases) (12,14,29) hinders scalability, posing challenges for multi-center validation and real-time implementation. Contrast-enhanced ultrasound (CEUS) utilizes 3D convolutional neural networks (CNNs) or multi-modal fusion to localize lesions (specificity: 82–91.45%), which is particularly applicable to MRI-negative patients (30), but is constrained by the high cost of targeted contrast agents and operational complexity. Multiparametric ultrasound (mpUS) integrates B-mode, shear wave elastography (SWE), and CEUS, demonstrating an AUC of 0.90 for PCa with GS >3+4 (31), though it suffers from cumbersome data acquisition and significant multi-modal noise. Finally, micro-ultrasound identifies small lesions via high resolution and self-supervised learning (AUC, 91%) (36), but its utility is limited by high equipment costs, restricted availability, and insufficient clinical validation data.

Table 2

Subgroup analysis of AI-based prostate cancer detection by ultrasound modality

Ultrasound modality Publication year Research team Core methodology Data scale (patients/images/videos) Key performance metrics Core innovations
TRUS 1999 Ronco et al. (17) backpropagation ANN + 17 variables (clinical + 14 TRUS) 442 patients PPV 81.82%; NPV 96.95% Pioneered ANN for TRUS-based PCa diagnosis; outperformed logistic regression
2008 Han et al. (18) Multiresolution autocorrelation + clinical features + SVM 51 patients (51 TRUS images) Texture features: sensitivity 92–96%, specificity 90–90.5%; texture + clinical features: sensitivity 92–96%, specificity 91.9–95.9% Clinical feature integration; robust texture feature proposal
2010 Glotsos et al. (19) Texture features + 2-level decision tree + multi-classifier 165 patients (165 TRUS images) Normal 89.5%; infectious 79.6%; cancer 82.7% First 3-class discrimination; multi-classifier enhancement
2020 Huang et al. (20) Optical density + LBP/GMRF texture feature fusion + SVM 48 patients (342 TRUS images) Accuracy 70.93%; sensitivity 70%; specificity 71.74% Texture feature fusion; noise reduction preprocessing
2021 Liu et al. (21) S-Mask R-CNN + Inception-v3 562 TRUS images Segmentation Dice 0.87; classification AUC 0.918; F1 0.65–0.83 Segmentation-classification integration; pixel-level prostate localization
2022 Hassan et al. (15) Pre-trained CNNs + ML classifier fusion + LIME XAI 1,151 participants (611,119 US/MRI images) US accuracy 97%; MRI fusion accuracy 88% Fusion-boosted MRI accuracy; XAI interpretability
2022 Akatsuka et al. (22) Xception + SVM + integrated data (ultrasound + clinical indicators) 691 patients (2,676 images) High-grade PCa: AUC 0.835; systematic biopsy subset AUC 0.831 Quantitative image selection; integrated data boosts high-grade PCa triage accuracy
2022 Lu et al. (7) Automatic region-based Gleason grading network (RLOD + GNet) 525 TRUS images (GS <7:80; GS =7:160; GS >7:285) Grading precision 0.830; RLOD Dice 0.815 End-to-end Gleason grading from TRUS; CFPN enhances small lesion detection
2023 Sun et al. (16) 2D/3D CNN (P-Net) + TRUS videos 832 patients (multi-institutional)/832 videos 3D P-Net: AUC 0.85–0.89; unnecessary biopsy rate 25.8% Standardized video acquisition; self-supervised learning reduced labeled data demand
2023 Lu et al. (23) SDABL (self-supervised dual attention + contrastive learning) 184 patients (1,195 TRUS images) Accuracy 80.46%; malignant F1 82.67% Dual attention; no negative pairs; low annotation dependency
2023 Lorusso et al. (24) ANN A/C-TRUS (AI neural network) + TRUS image analysis 64 patients (384 prostate sectors) Overall accuracy 78%; CSPCa sensitivity 69%; high-grade PCa NPV 91% No inter-observer variability; low-cost; universal TRUS compatibility
2024 Li et al. (25) FPN model (ResNet50 + biopsy needle tract images + original TRUS images) 142 patients (1,696 TRUS images) AUC 0.934; sensitivity 82.9%; specificity 96.6% Needle tract-image fusion; no ROI subjectivity; outperforms radiologists
2025 Lu et al. (26) DAML network (SDMS + LIAS + PARL) + KNN classifier 184 patients (1,195 TRUS images) Malignant F1 0.888; benign F1 0.852 Multiple metric learning strategies; low augmentation dependency
2025 Lou et al. (27) I3D 3D deep learning + TRUS video clips (multicenter validation) 815 patients (TRUS video clips) AUC 0.86–0.91; sensitivity 81–91%; specificity 82–85% Spatiotemporal feature capture; outperforms conventional methods; MRI-negative detection
2025 Rusu et al. (28) ProCUSNet (nnUNet-based 3D segmentation) + B-mode TRUS images 2,986 patients (3,449 3D TRUS volumes) Clinically significant cancer sensitivity 0.78–0.86 Large-scale B-mode TRUS AI; MRI-comparable; ultrasound-only targeting
TeUS 2018 Azizi et al. (12) Deep RNN (LSTM/GRU) + TeUS 157 patients (255 biopsy cores) AUC 0.96; sensitivity 0.76; specificity 0.98; accuracy 0.93 Temporal TeUS modeling; outperforms spectral analysis; adequacy of short sequences
2019 Sedghi et al. (14) Unsupervised deep neural network mapping + TeUS 157 patients (255 biopsy cores) High-grade PCa: AUC >0.8 Unsupervised TeUS learning; unlabeled data utilization; probability color maps
2022 Javadi et al. (29) Iterative noisy label refinement + TeUS + biopsy location fusion 90 patients (353 biopsy cores) AUC 0.73; sensitivity 80%; specificity 63%; accuracy 69% Noisy label handling; iterative cleaning; location integration
CEUS 2019 Feng et al. (30) 3D-CNN + targeted/non-targeted CEUS (anti-PSMA agent) 20 xenografts (47,578 CEUS tensor samples) Targeted CEUS: specificity 91.45%; accuracy 90.18% Targeted CEUS application; spatiotemporal feature extraction; superior to traditional methods
mpUS 2020 Wildeboer et al. (31) Random forest + multiparametric US (B-mode + SWE + CEUS) 48 patients Gleason >3+4: AUC 0.90; PCa: AUC 0.75 Multimodal + radiomics fusion; zonal segmentation; superior to single modalities
2023 Zhang et al. (32) ANN + multimodal TRUS (2D-US + TRTE + CEUS) + PSA 301 patients ANN model: AUC 0.855; sensitivity 80%; specificity 88.6% Multimodal ultrasound-PSA integration
2023 Jager et al. (33) ML + 3D multiparametric TRUS (3D B-mode + 3D SWE + 4D CEUS) 715 patients (prospective multicenter) AUC for CSPCa (ISUP GG ≥2) 3D multiparametric integration; histopathology ground truth; prospective design
2024 Wu et al. (34) 3D ResNet-50 + B-mode/SWE + fusion + orthogonal regularization 512 patients (512 TRUS videos) AUC 0.84; F1 0.86; accuracy 0.79 Bimodal adaptive fusion; redundancy reduction; CAM-guided biopsy
2024 Wu et al. (35) 3D ResNet-50 + B-mode/SWE + few-shot segmentation + prototype correction 512 patients (512 TRUS videos) AUC 0.86; F1 0.87; accuracy 0.81 Multi-task fusion; limited mask adaptation; biopsy guidance
Micro-Ultrasound 2023 Wilson et al. (36) Self-supervised learning (VICReg) + micro-ultrasound data + supervised fine-tuning 391 patients (1,028 biopsy cores) AUC 91%, outperforms supervised learning Pioneering SSL application; labeled data scarcity solution; cross-center generalization
2025 Harmanani et al. (37) TRUSWorthy: SSL (VICReg) + Transformer-based MIL + RUSBoost + deep ensemble 693 patients (6,607 biopsy cores) AUC 79.9%; balanced accuracy 71.5% 4-challenge integrated solution; uncertainty calibration; cross-center robustness

AI, artificial intelligence; ANN, artificial neural network; AUC, area under the receiver operating characteristic curve; CAM, class activation mapping; CEUS, contrast-enhanced ultrasound; CFPN, connected feature pyramid network; CNN, convolutional neural network; CSPCa, clinically significant prostate cancer; Dice, dice similarity coefficient; FPN, feature pyramid network; GG, Grade Group; GMRF, Gaussian Markov random field; GRU, gated recurrent unit; GS, Gleason score; ISUP, International Society of Urological Pathology; KNN, K-nearest neighbor; LBP, local binary pattern; LIME, local interpretable model-agnostic explanations; LSTM, long short-term memory; MIL, multiple instance learning; ML, machine learning; mpUS, multiparametric ultrasound; MRI, magnetic resonance imaging; NPV, negative predictive value; PCa, prostate cancer; PPV, positive predictive value; PSA, prostate-specific antigen; PSMA, prostate-specific membrane antigen; RLOD, region labeling object detection; RNN, recurrent neural network; ROI, region of interest; SDABL, self-supervised dual-head attentional bootstrap learning network; SSL, self-supervised learning; SVM, support vector machine; SWE, shear-wave elastography; TeUS, temporal enhanced ultrasound; TRTE, transrectal tissue elasticity; TRUS, transrectal ultrasound; US, ultrasound.

Notably, few systematic reviews synthesize TRUS-based AI models for PCa detection, CSPCa identification, and PCa risk stratification. The current research status in this field is summarized below:

Current status of AI-based PCa diagnosis using TRUS images

In 2019, Feng et al. conducted an experiment using 20 mice implanted with human PCa xenografts. They acquired CEUS videos of the tumor lesions and constructed a 3D CNN model for PCa detection, leveraging sequential CEUS frames (30). Specifically, the model performed 3D convolutional operations to uniformly extract spatial and temporal features from sequential CEUS frames, enabling automated PCa detection in ultrasound image sequences. Notably, this study attempted to integrate CEUS with a prostate-specific membrane antigen (PSMA)-targeted contrast agent for automated PCa detection and compared this approach with non-targeted blank agents. Results showed that the targeted deep learning model improved PCa detection sensitivity by >10% compared with non-targeted agents. For targeted CEUS images, the model achieved a specificity of >91% and accuracy of 90%.

In 2020, Huang et al. used biopsy results as the reference standard to collect longitudinal prostate images acquired before and during biopsy (48 patients, 342 pairs of images) (20). Based on the positional correspondence of the biopsy needle between pre- and intra-biopsy images, researchers manually annotated needle positions from intra-biopsy images onto pre-biopsy images. Rectangular image strips in pre-biopsy images—corresponding to biopsy needle positions—were designated as regions of interest (ROIs). Texture features were extracted from preprocessed ROIs, linearly combined, and input into a support vector machine (SVM) classifier for PCa classification. This approach achieved a diagnostic accuracy of 70.93%, sensitivity of 70.00%, and specificity of 71.74% (20). Due to the small sample size, the authors did not explore the model’s ability to distinguish between three-tier or five-tier PCa risk categories.

In 2021, Liu et al. similarly used biopsy results as the reference standard to collect 702 cross-sectional TRUS prostate images (21). First, three specialists with >5 years of clinical experience delineated prostate tissue boundaries to establish image labels. A deep learning model combining S-Mask region-based convolutional neural network (R-CNN) and Inception-v3 was developed for auxiliary PCa diagnosis. The modified S-Mask R-CNN enabled accurate segmentation of prostate ultrasound images and generation of candidate regions, with an ROI alignment algorithm for pixel-level feature localization. Convolutional networks generated binary masks to segment prostate tissue from the background, and the Inception-v3 network was used for lesion detection. Experimental results showed this method achieved an 80% accuracy for PCa detection.

In 2022, Hassan et al. proposed a novel automated classification algorithm for PCa detection from TRUS and MRI images by fusing multiple deep learning approaches (15). Custom layers were added to pre-trained models (MobileNetV2, InceptionResNetV2, ResNet50V2, ResNet101V2, ResNet152V2, Xception, VGG16, VGG19, and InceptionV3), which were applied to MRI and TRUS datasets from The Cancer Imaging Archive (611,119 images). The best-performing model achieved 97% accuracy on TRUS test data and 80% on MRI test data. To improve MRI performance, the top model was used as a feature extractor and combined with shallow machine learning algorithms (SVM, gradient boosting, and random forest) to develop a fused model. This fusion strategy significantly enhanced PCa detection, increasing MRI accuracy from 80% to 88%.

In 2024, Li et al. collected 1,696 pairs of pre- and intra-biopsy oblique-section TRUS grayscale images from 142 patients. Using biopsy results as the reference standard, they trained a ResNet50 model with three input modalities: original images (Whole model), biopsy needle tract images (Needle model), and combined images [feature pyramid networks (FPN)] (25). For the Needle model, all images underwent bilinear interpolation followed by symmetric normalization (a widely used medical image registration algorithm). The resulting deformation field was interpolated onto intra-biopsy images to generate registered images. In the test set, the FPN achieved an AUC of 0.934, specificity of 0.966, and sensitivity of 0.829—significantly outperforming the Whole model (AUC =0.908, specificity =0.938, sensitivity =0.754) and Needle model (AUC =0.905, specificity =0.918, sensitivity =0.764) (P<0.05) (25). However, the small sample size (1,696 2D TRUS images from 142 patients) precluded exploration of the model’s ability to stratify PCa into three-tier or five-tier risk groups.

Current status of AI-based CSPCa diagnosis using TRUS images

In 2023, Sun et al. prospectively evaluated pre-biopsy cross-sectional TRUS videos from 832 patients across four centers to develop an AI model for CSPCa identification (16). Using prostate biopsy or radical prostatectomy pathology as the reference standard, they constructed 2D and 3D P-Net CNN models using a training dataset (559 patients, with only intra-prostate contour images included). Models were tested on internal (140 patients) and external (133 patients) validation datasets. For CSPCa prediction, the 3D P-Net achieved an AUC of 0.89 [95% confidence interval (CI): 0.83–0.95] in internal testing and 0.85 (95% CI: 0.78–0.93) in external validation, whereas the 2D P-Net yielded AUCs of 0.86 (95% CI: 0.80–0.93) and 0.79 (95% CI: 0.71–0.87), respectively (16). Similar to prior studies, the authors did not investigate the models’ performance in three-tier or five-tier PCa risk stratification.

In 2023, Zhang et al. explored the value of a machine learning model integrating multimodal TRUS (grayscale, real-time elastography, CEUS) and prostate-specific antigen (PSA)-related parameters (total serum PSA, free PSA, free-to-total PSA ratio) for CSPCa diagnosis (32). Pathological results from 301 biopsy patients (218 CSPCa, 83 CISPCa) served as the gold standard. Six machine learning models were compared: artificial neural network (ANN), logistic regression, SVM, decision tree, random forest, and k-nearest neighbor. The ANN model performed best, achieving a sensitivity of 80%, specificity of 88.6%, and AUC of 0.855 (32).

In 2024, Wu et al. collected cross-sectional TRUS videos from 512 biopsy patients (346 CSPCa, 166 CISPCa), all of whom underwent SWE (34). A CSPCa identification model was developed using these multimodal data: two 3D ResNet-50 models extracted features from TRUS grayscale hypoechoic regions and SWE abnormally stiff regions, respectively. An adaptive spatial fusion module aggregated features from the two modalities, with orthogonal regularization to reduce feature redundancy and enhance weight orthogonality. The model achieved a favorable AUC of 0.84 for CSPCa identification.

In 2024, Takeda et al. collected multimodal data from 151 ultrasound-guided biopsy patients, including PSA results, TRUS images, and MRI sequences [T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and apparent diffusion coefficient (ADC) maps] (38). A pre-trained Xception CNN (39) was evaluated for CSPCa prediction in the full cohort (n=151) and a subset with PSA ≤20 ng/mL (n=122). AUC values for CSPCa prediction in the full cohort were as follows: (I) PSA testing: 0.649 (95% CI: 0.467–0.832); (II) TRUS images: 0.715 (95% CI: 0.551–0.878); (III) T2WI: 0.738 (95% CI: 0.581–0.895); (IV) DWI: 0.582 (95% CI: 0.396–0.767); (V) ADC maps: 0.690 (95% CI: 0.519–0.861); (VI) multimodal data: 0.878 (95% CI: 0.772–0.984). For the PSA ≤20 ng/mL subset, AUC values were: (I) PSA testing: 0.574 (95% CI: 0.330–0.819); (II) TRUS images: 0.708 (95% CI: 0.508–0.908); (III) T2WI: 0.803 (95% CI: 0.629–0.976); (IV) DWI: 0.564 (95% CI: 0.341–0.787); (V) ADC maps: 0.662 (95% CI: 0.449–0.874); (VI) multimodal data: 0.862 (95% CI: 0.723–1.000).

Current status of AI-based three-tier PCa risk stratification using TRUS images

The EAU adopts the D’Amico risk stratification, stratifying PCa into low-risk (GS ≤6), intermediate-risk (GS =7), and high-risk (GS ≥8) (7,8). Based on this system, PCa can be further subdivided into five subgroups: low-risk (GS ≤6), intermediate-risk (GS =7), high-risk (GS ≥8), low-to-intermediate risk (GS ≤7), and intermediate-to-high risk (GS ≥7).

AI-based prediction of low-to-intermediate-risk (GS ≤7) vs. high-risk (GS ≥8) PCa

In 2022, Akatsuka et al. tested three pre-trained deep CNN models (Xception, InceptionV3, VGG16) and selected Xception for its superior performance in ultrasound image classification (22). A total of 2,676 cross-sectional TRUS images from 691 patients were divided into training and test sets based on ultrasound evaluation date. Two deep learning analyses were performed with different labeling strategies: first, distinguishing PCa (GS ≥6) from non-PCa (AUC =0.693); second, distinguishing high-risk (GS ≥8) from low-to-intermediate-risk (GS ≤7) PCa (AUC =0.723) (22). Integrating TRUS images with clinical data (age, PSA levels) into the Xception model substantially improved high-risk PCa prediction (AUC =0.835) (22). Research in this domain remains limited, and these findings require validation across different ultrasound devices and observer cohorts.

AI-based prediction of low-risk (GS ≤6), intermediate-risk (GS =7), and high-risk (GS ≥8) PCa

In 2022, Lu et al. collected 525 cross-sectional TRUS images of biopsy-confirmed PCa, integrating biopsy needle tract information, biopsy results, and MRI findings (7). PCa lesions were manually delineated to label ROIs, and a deep learning-based Automatic Region-based Gleason Grading network was proposed to differentiate low-, intermediate-, and high-risk PCa. The network first identified PCa lesions via a region-marked object detection network, followed by Gleason grading of marked regions. The model achieved an accuracy of 0.830 for three-tier risk stratification. However, the authors did not investigate the model’s utility for five-tier GG stratification or its performance using TRUS alone (without integrating MRI or biopsy data).

Current status of AI-based five-tier PCa risk stratification using TRUS images

With the growing demand for refined risk stratification, the ISUP classified PCa into five GGs (five-tier risk stratification) (6): GG1 (GS 3+3), GG2 (GS 3+4), GG3 (GS 4+3), GG4 (GS 8), and GG5 (GS 9 or 10). Based on this system, PCa can be subdivided into 11 subgroups as outlined in the Introduction section.

AI-based prediction of below-intermediate-risk (GG1–2) vs. intermediate-risk and above (GG3–5) PCa

In 2023, Lorusso et al. retrospectively analyzed cross-sectional TRUS images from 64 patients, using post-radical prostatectomy whole-mount pathology as the reference standard (24). A computer-aided ANN analysis model was proposed, and suspicious lesions identified by the model were compared with pathological cancer foci. For detecting intermediate-risk and above PCa (GG3–5), the model achieved a sensitivity of 69%, specificity of 77%, negative predictive value of 88%, positive predictive value of 50%, and accuracy of 75%. Tumor volume did not affect the model’s diagnostic performance (24).

In 2020, Wildeboer et al. collected TRUS grayscale images, SWE data, and CEUS data from 50 biopsy-confirmed PCa patients, using radical prostatectomy pathology as the reference standard (31). A random forest classifier was developed based on multimodal TRUS, involving four steps: prostate segmentation [via a deep learning-based algorithm (40)], data registration, feature extraction, and multiparametric classification. Hemodynamic features from CEUS videos were extracted and converted to 2D to match SWE and grayscale image dimensions. Radiomic features (pixel values, lesion capsule spiculation, perfusion/elasticity asymmetry) were extracted from hemodynamic maps, SWE, and grayscale images, then combined via random forest. The classifier achieved an AUC of 0.75 for PCa diagnosis and 0.90 for predicting intermediate-risk and above PCa (GG3–5) (31).

AI-based prediction of below-high-risk (GG1–4) vs. high-risk (GG5) PCa

To date, no literature has reported AI-based TRUS models for binary classification of below-high-risk (GG1–4) vs. high-risk (GG5) PCa.

AI-based prediction of all five GG tiers (GG1–GG5) PCa

To date, no studies have reported AI-based TRUS models for five-class PCa classification into GG1 (low-risk), GG2 (low-to-intermediate-risk), GG3 (intermediate-risk), GG4 (intermediate-to-high-risk), and GG5 (high-risk) groups.


Conclusions

Overall, TRUS-based AI for PCa risk stratification (three-tier and five-tier) remains underdeveloped, with a paucity of relevant studies. Key challenges are summarized as follows: (I) Unclear PCa lesion localization in some TRUS images hinders accurate annotation for model training. (II) Assigning risk stratification labels to TRUS lesions requires specialized clinical and pathological expertise, increasing dataset annotation difficulty. (III) Insufficient data for specific risk groups and imbalanced group distribution are common, leading to model overfitting, poor generalization, and limited utility for refined stratification (e.g., five-tier). (IV) Most studies rely on single-center retrospective data, and their generalizability requires validation in multi-center prospective cohorts.

Future advancements in TRUS equipment, novel technologies, high-quality dataset accumulation, AI algorithm optimization, multimodal data integration, and multi-institutional collaboration are expected to enable TRUS-based AI to accurately predict and diagnose PCa, CSPCa, and both three-tier (EAU) and five-tier (ISUP) risk stratification in real time. Such progress will provide reliable evidence for treatment decision-making, improving the efficiency of PCa diagnosis and management.


Acknowledgments

None.


Footnote

Reporting Checklist: The authors have completed the Narrative Review reporting checklist. Available at https://gs.amegroups.com/article/view/10.21037/gs-2025-aw-504/rc

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-2025-aw-504/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-2025-aw-504/coif). The authors have no conflicts of interest to declare.

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Cite this article as: Zhang Q, Zhou C, Chen Y, Luo Y. Artificial intelligence for prostate cancer detection and risk stratification using transrectal ultrasound: a narrative review. Gland Surg 2026;15(2):52. doi: 10.21037/gs-2025-aw-504

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