The Micro-ultrasound Guided Prostate Biopsy in Detection of Prostate Cancer: A Systematic Review and Meta-Analysis

A Propensity Score-matched Comparison of Micro-ultrasound-guided Transrectal and Magnetic Resonance Imaging/Transrectal Ultrasound Fusion-guided Transperineal Prostate Biopsies for Detection of Clinically Significant Prostate Cancer

Background and objective

High-resolution micro-ultrasound (microUS) is an advanced imaging tool. Our objective was to determine whether systematic microUS use for transrectal biopsy (TRBx) improves the detection rate for clinically significant prostate cancer (csPCa) in comparison to transperineal biopsy (TPBx) performed with magnetic resonance imaging (MRI)/conventional transrectal ultrasound (TRUS) fusion software.

Methods

We retrospectively analyzed data for men who underwent prostate biopsies, including those on active surveillance (AS). TRBx was performed under microUS guidance, while MRI/TRUS fusion was consistently used to guide TPBx. Patients were matched according to propensity score matching (PSM). The primary endpoint was comparison of the csPCa detection rate with the two approaches. Secondary endpoints included predictors of csPCa (International Society of Urological Pathology grade group ≥2, assessed via multivariable logistic regression) and complication rates.

Key findings and limitations

Overall, 1423 patients were enrolled. After applying PSM we identified an analytical cohort of 1094 men, 582 in the TRBx group and 512 in the TPBx group. There was no significant difference in the csPCa detection rate between the TRBx (45%) and TPBx (51%) groups (p = 0.07). Complications occurred in nine of 1094 patients (1%). On adjusted multivariable analysis, TPBx had a similar csPCa detection rate to TRBx (adjusted odds ratio [aOR] 1.26;p = 0.09). Predictors of csPCa detection were a positive family history (aOR 1.68; 95% confidence interval [CI] 1.20-2.35; p = 0.002); age (aOR 1.04, 95% CI 1.02-1.06; p < 0.001); positive digital rectal examination (aOR 2.35, 95% CI 1.70-3.25; p < 0.001); prostate-specific antigen density ≥0.15 ng/ml/cm3 (aOR 3.23, 95% CI 2.47-4.23; p < 0.001); and a Prostate Imaging-Reporting and Data System score ≥3 (aOR 2.46; 95% CI 1.83-3.32; p < 0.001). Limitations include the retrospective nature of the study, the risk of underestimating the complication rate, and the heterogeneity of biopsy indications.

Conclusions and clinical implications

TRBx using microUS alone showed a comparable csPCa detection rate to TPBx guided by MRI/TRUS fusion software. Given the better visualization and real-time detection of suspicious zones with microUS, the potential for improvement in the csPCa detection rate with greater integration of microUS in the TPBx setting warrants further investigation.

Patient summary

We compared the ability of two different prostate biopsy approaches to detect clinically significant prostate cancer. We found that transrectal biopsy guided by micro-ultrasound had similar detection rates to transperineal biopsy guided by a combination of magnetic resonance imaging and conventional ultrasound. More research is needed to confirm the potential of micro-ultrasound for transperineal biopsy.

Microultrasound in the detection of the index lesion in prostate cancer

INTRODUCTION AND OBJECTIVE

The natural progression of prostate cancer is primarily driven by an index lesion (IL). Studies have shown that different metastases within the same patient arise from a single precursor cell. Therefore, our aim is to assess the effectiveness of transrectal microultrasound (MUS) in comparison to multiparametric magnetic resonance imaging (mpMRI) for detecting the IL in prostate cancer. We used quarter-mount pathological results as the reference standard for this evaluation.

MATERIALS AND METHODS

Three hundred and sixty-three patients who underwent Robot-Assisted Radical Prostatectomy (RARP) from June 2021 to August 2022 were included. All received mpMRI and MUS before RARP. MUS was performed by experienced operators blinded to mpMRI and biopsy results. The IL in the radical prostatectomy specimen was defined as the lesion with extraprostatic extension, the highest Grade Group (GG), or the largest tumor volume if the GG was the same. The correlation between imaging and final pathology findings was performed. A descriptive statistical analysis is presented.

RESULTS

The patients' prostates were analyzed in 12 regions (anterior/posterior, right/left, apex/mid/base). A total of 4308 regions were identified. Of these, 935 were involved by the ILs. Compared with final pathology, MUS demonstrated a sensitivity, specificity, PPV, and NPV of 68.7%, 96.3%, 80.8%, and 93.1%, respectively, while mpMRI showed a sensitivity, specificity, PPV, and NPV of 68.6%, 97.2%, 86.1%, and 92.5%, respectively, for the detection of the IL. Most of the lesions missed by MUS were located in the anterior zone (62%).

CONCLUSION

MUS exhibits a diagnostic performance similar to mpMRI when it comes to detecting the IL in prostate cancer. MUS is a cost-effective option, offers real-time evaluation, and has no delay in the acquisition process.

Prostate Cancer Diagnosis with Micro-ultrasound: What We Know now and New Horizons

Prostate cancer (PCa) is the most common non-cutaneous cancer diagnosed in males. Multiparametric Magnetic Resonance Imaging (mpMRI) with targeted biopsy can detect PCa and is currently the recommended initial test in men at risk for PCa. Micro-Ultrasound (MicroUS) is a novel high-resolution 29-MHz ultrasound with ∼three times greater resolution of conventional transrectal ultrasound (TRUS) resolution. Preliminary data suggest improved accuracy of ultrasound for targeted prostate biopsy. A growing body of evidence has become available supporting MicroUS as a potentially time and cost saving modality for PCa detection, with early results suggesting comparable accuracy to mpMRI. Additionally, microUS allows real-time visualization for accurate targeted biopsy. It is not yet clear whether MicroUS should be used on its own or in combination with mpMRI for prostate cancer detection. The ongoing OPTIMUM randomized controlled trial will help to establish the role of MicroUS in the diagnostic algorithm for the detection of clinically significant (cs)-PCa. Early data also indicate this imaging modality may have a role in local staging (eg, extracapsular extension prediction) and active surveillance of PCa. MicroUS has also the potential to add value to biparametric (bp) MRI, and may represent a promising tool for guidance of focal therapy in the near future.

The diagnostic accuracy of micro-ultrasound for prostate cancer diagnosis: a review

PURPOSE

Micro-UltraSound (microUS) is a new imaging modality capable of identifying and targeting suspicious areas, which might further increase the diagnostic yield of prostate biopsy (PBx). Aim of this review is to provide insights into the usefulness of microUS for the sub-stratification of prostate cancer (PCa), clinically significant PCa (i.e., any Gleason score ≥ 7 PCa; csPCa) along with non-organ-confined disease in patients undergoing PBx.

METHODS

A PubMed literature search was performed using keywords: prostate cancer diagnosis, prostate cancer diagnosis surveillance, systematic biopsy, target biopsy, micro-ultrasound, and prostate risk identification using micro-ultrasound.

RESULTS

MicroUS could significantly improve multiparametric magnetic resonance imaging (mpMRI) findings by adding valuable anatomical and pathological information provided by real-time examination. Furthermore, microUS target biopsy could replace systematic biopsy in clinical practice by reducing the detection of clinically insignificant (ciPCa) and increasing that of csPCa. Finally, microUS may be useful in predicting the presence of non-organ confined PCa before radical prostatectomy and it could also be an effective add-on tool for patient monitoring within the active surveillance program.

CONCLUSION

MicroUS may represent an attractive step forward for the management of csPCa as a complementary or alternative tool to mpMRI. Nevertheless, further longitudinal studies are warranted, and the strength of the evidence is still suboptimal to provide clear recommendations for daily clinical practice.

Robotically controlled three-dimensional micro-ultrasound for prostate biopsy guidance

PURPOSE

Prostate imaging to guide biopsy remains unsatisfactory, with current solutions suffering from high complexity and poor accuracy and reliability. One novel entrant into this field is micro-ultrasound (microUS), which uses a high-frequency imaging probe to achieve very high spatial resolution, and achieves prostate cancer detection rates equivalent to multiparametric magnetic resonance imaging (mpMRI). However, the ExactVu transrectal microUS probe has a unique geometry that makes it challenging to acquire controlled, repeatable three-dimensional (3D) transrectal ultrasound (TRUS) volumes. We describe the design, fabrication, and validation of a 3D acquisition system that allows for the accurate use of the ExactVu microUS device for volumetric prostate imaging.

METHODS

The design uses a motorized, computer-controlled brachytherapy stepper to rotate the ExactVu transducer about its axis. We perform geometric validation using a phantom with known dimensions and compare performance with magnetic resonance imaging (MRI) using a commercial quality assurance anthropomorphic prostate phantom.

RESULTS

Our geometric validation shows accuracy of 1 mm or less in all three directions, and images of an anthropomorphic phantom qualitatively match those acquired using MRI and show good agreement quantitatively.

CONCLUSION

We describe the first system to acquire robotically controlled 3D microUS images using the ExactVu microUS system. The reconstructed 3D microUS images are accurate, which will allow for future applications of the ExactVu microUS system in prostate specimen and in vivo imaging.

Micro-Ultrasound: Current Role in Prostate Cancer Diagnosis and Future Possibilities

Prostate Cancer (PCa) is the second most common cancer in men. Population screening using prostate specific antigen (PSA) blood test and digital rectal exam (DRE) is recommended by the NCCN, EAU and other prominent clinical guidelines. While MRI is the recommended initial test in men at risk for PCa, micro-Ultrasound (MicroUS) is a novel high resolution ultrasound technology that has shown promise in PCa detection. This article provides a narrative review of the studies to date which have been conducted to evaluate the functionality and efficacy of MicroUS within the patient care pathway for prostate cancer. A total of 13 relevant publications comparing detection of csPCa between MicroUS and mpMRI were selected. An amount of 4 publications referring to use of MicroUS for other indications were found. Each publication was evaluated for risk of bias and applicability using the Quality Assessment of Diagnostic Accuracy (QUADAS-2) tool. The studies reviewed conclude that MicroUS detection rates for clinically significant prostate cancer diagnosis are comparable to the detection rates of mpMRI guided biopsy procedures. While the existing literature indicates that MicroUS should replace conventional TRUS for prostate imaging and biopsy, it is not yet clear whether MicroUS should be used on its own or in conjunction with mpMRI for augmenting prostate cancer detection. The ongoing OPTIMUM trial will provide evidence on how best to utilize this new technology. Early data also suggest this flexible new imaging modality has a place in local staging and active surveillance of prostate cancer as well as in bladder cancer staging.

Micro-Ultrasound in the Diagnosis and Staging of Prostate and Bladder Cancer: A Comprehensive Review

Background and Objectives: Multiparametric magnetic resonance imaging (mpMRI) of the prostate and prostate-specific membrane antigen positron emission tomography (PSMA PET) are some examples of how the advancement of imaging techniques have revolutionized the diagnosis, staging, and consequently management of patients with prostate cancer (PCa). Although with less striking results, novel radiological modalities have also been proposed for bladder cancer (BCa) in recent years. Micro-ultrasound (MUS) is an imaging examination characterized by high real-time spatial resolution, recently introduced in the urological field. This article aimed to describe the current evidence regarding the application of MUS for the diagnosis and staging of PCa and BCa. Materials and Methods: We designed a narrative review. A comprehensive search in the MEDLINE, Scopus, and Cochrane Library databases was performed. Articles in English-language and published until July 2022 were deemed eligible. Retrospective and prospective primary clinical studies, as well as meta-analyses, were included. Results: MUS-guided prostate biopsy showed high sensitivity (0.91, 95% CI, 0.79-0.97) in the diagnosis of clinically significant PCa (csPCa). It was associated with a higher detection rate of csPCa than a systematic biopsy (1.18, 95% CI 0.83-1.68). No significant difference was found between MUS and mpMRI-guided biopsy in the total detection of PCa (p = 0.89) and in the detection of Grade Groups ≥ 2 (p = 0.92). The use of MUS to distinguish between non-muscle-invasive and muscle-invasive BCa was described, highlighting an up-staging with MUS only in a minority of cases (28.6%). Conclusions: Promising findings have emerged regarding the feasibility and accuracy of MUS in the diagnosis and staging of PCa and BCa. However, the available evidence is limited and should be considered preliminary.

Alternatives for MRI in Prostate Cancer Diagnostics-Review of Current Ultrasound-Based Techniques

The purpose of this review is to present the current role of ultrasound-based techniques in the diagnostic pathway of prostate cancer (PCa). With overdiagnosis and overtreatment of a clinically insignificant PCa over the past years, multiparametric magnetic resonance imaging (mpMRI) started to be recommended for every patient suspected of PCa before performing a biopsy. It enabled targeted sampling of the suspicious prostate regions, improving the accuracy of the traditional systematic biopsy. However, mpMRI is associated with high costs, relatively low availability, long and separate procedure, or exposure to the contrast agent. The novel ultrasound modalities, such as shear wave elastography (SWE), contrast-enhanced ultrasound (CEUS), or high frequency micro-ultrasound (MicroUS), may be capable of maintaining the performance of mpMRI without its limitations. Moreover, the real-time lesion visualization during biopsy would significantly simplify the diagnostic process. Another value of these new techniques is the ability to enhance the performance of mpMRI by creating the image fusion of multiple modalities. Such models might be further analyzed by artificial intelligence to mark the regions of interest for investigators and help to decide about the biopsy indications. The dynamic development and promising results of new ultrasound-based techniques should encourage researchers to thoroughly study their utilization in prostate imaging.