Is multiparametric MRI always needed in biopsy-naïve patients with abnormal digital rectal examination? A single-institutional experience combining clinical and micro-ultrasonography-based factors to optimize prostate cancer detection.

PURPOSE: To assess the diagnostic performance of microultrasound-targeted biopsy (microUSTBx) and systematic biopsy (SBx) in detecting clinically significant prostate cancer (csPCa) among men with abnormal digital rectal examination (DRE) and suspicious lesions at multiparametric magnetic resonance imaging (mpMRI), and to compare the diagnostic performance of this approach with a mpMRI-guided targeted biopsy (MTBx) plus SBx-based strategy. METHODS: Biopsy-naïve men with suspicious lesions at mpMRI and abnormal DRE were prospectively evaluated between October 2017 and January 2023. csPCa detection rate by microUSTBx plus SBx and MTBx plus SBx was assessed and then compared by McNemar's test. The added value of prostate-specific antigen density (PSAd) was also evaluated. RESULTS: Overall, 182 biopsy naïve men were included. MicroUSTBx plus SBx achieved comparable detection rate to MTBx plus SBx in diagnosis of ciPCa and csPCa (ciPCa: 9.3% [17/182] vs 10% [19/182]; csPCa: 63% [114/182] vs 62% [113/182]). MicroUSTBx outperformed MTBx (ciPCa: 5.5% [10/182] vs 6.0% [11/182]; csPCa: 57% [103/182] vs 54% [99/182]). Using microUSTBx plus SBx would have avoided 68/182 (37%) unnecessary mpMRI, while missing only 2/116 (1.7%) csPCa. The decision curve analysis of suspicious microUS plus PSAd ≥ 0.15 ng/ml showed higher net benefit in the ability to identify true positives and reduce the number of unnecessary prostate biopsy in this subcategory of patients. CONCLUSIONS: The combination of microUSTBx and SBx showed equal diagnostic performance to an mpMRI-based approach in biopsy-naïve patients with an abnormal DRE. The combination of this approach with PSAd maximize the diagnostic accuracy while lowering the need for unnecessary biopsies.

Diagnostic performance of microUltrasound at MRI-guided confirmatory biopsy in patients under active surveillance for low-risk prostate cancer.

BACKGROUND: Active surveillance (AS) represents a standard of care of low-risk prostate cancer (PCa). However, the identification and monitoring of AS candidates remains challenging. Microultrasound (microUS) is a novel high-resolution imaging modality for transrectal ultrasonography (TRUS). We explored the impact of microUS TRUS and targeted biopsies in mpMRI-guided confirmatory biopsies. METHODS: Between October 2017 and September 2021, we prospectively enrolled 100 patients scheduled for MRI-guided confirmatory biopsy at 1 year from diagnosis of ISUP 1 PCa. TRUS was performed using the ExactVu microUS system; PRI-MUS protocol was applied to identify suspicious lesions (i.e., PRIMUS score ≥ 3). All patients received targeted biopsies of any identified microUS and mpMRI lesions and complementary systematic biopsies. The proportion of patients upgraded to clinically significant PCa (defined as ISUP ≥ 2 cancer; csPCa) at confirmatory biopsies was determined, and the diagnostic performance of microUS and mpMRI were compared. RESULTS: Ninety-two patients had a suspicious MRI lesion classified PI-RADS 3, 4, and 5 in respectively 28, 16, and 18 patients. MicroUS identified 82 patients with suspicious lesions, classified as PRI-MUS 3, 4, and 5 in respectively 20, 50, and 12 patients, while 18 individuals had no lesions. Thirty-four patients were upgraded to ISUP ≥ 2 cancer and excluded from AS. MicroUS and mpMRI showed a sensitivity of 94.1% and 100%, and an NPV of 88.9% and 100%, respectively, in detecting ISUP ≥ 2 patients. A microUS-mandated protocol would have avoided confirmatory biopsies in 18 patients with no PRI-MUS ≥ 3 lesions at the cost of missing four upgraded patients. CONCLUSIONS: MicroUS and mpMRI represent valuable imaging modalities showing high sensitivity and NPV in detecting csPCa, thus allowing their use for event-triggered confirmatory biopsies in AS patients. MicroUS offers an alternative imaging modality to mpMRI for the identification and real-time targeting of suspicious lesions in AS patients.

Diagnostic accuracy of multiparametric MRI- and microultrasound-targeted biopsy in biopsy-naïve patients with a PI-RADS 5 lesion: a single-institutional study.

PURPOSE: To evaluate the diagnostic accuracy of multiparametric magnetic resonance imaging (MRI)- and microultrasound (microUS)-guided targeted biopsy (TBx) in detecting prostate cancer (PCa) and clinically significant (cs) PCa among men with Prostate Imaging Reporting and Data System (PI-RADS 5) lesions and to compare this combined TBx (CTBx) strategy with CTBx plus systemic biopsy (SBx). METHODS: One hundred and thirty-six biopsy-naïve patients with PI-RADS 5 lesion at multiparametric MRI undergoing CTBx plus SBx were retrospectively evaluated. Analysis of diagnostic performance of microUS-TBx, MRI-TBx, CTBx, SBx and combined CTBx plus SBx was performed. Cost (downgrade, upgrade and biopsy core) to effectiveness (detection rate) was compared. RESULTS: CTBx achieved a comparable detection rate to CTBx plus SBx in diagnosis of PCa and csPCa (PCa: 78.7% [107/136] vs 79.4% [108/136]; csPCa: 67.6% [92/136] vs 67.6% [92/136]; p > 0.05) and outperformed SBx (PCa: 58.8% [80/136]; csPCa: 47.8% [65/136]; p < 0.001). Using CTB would have avoided 41.1% (56/136) unnecessary SBx, without missing any csPCa. The rate of any upgrading or csPCa upgrading was significantly higher by SBx than by CTBx [33/65 (50.8%) vs 17/65 (26.1%) and 20/65 (30.8%) vs 4/65 (6.15%), respectively, p < 0.05]. Considering csPCa detection rate, microUS showed high sensitivity and positive predictive value (94.6%, 87.9%, respectively), with lower specificity and negative predictive value (25.0% and 44.4%, respectively). At multivariable logistic regression models, positive microUS was identified as an independent predictor of csPCa (p = 0.024). CONCLUSIONS: A combined microUS/MRI-TBx approach could be the ideal imaging tool for characterizing primary disease in PI-RADS five patients, allowing SBx to be avoided.

Assessing cancer risk in the anterior part of the prostate using micro-ultrasound: validation of a novel distinct protocol.

PURPOSE: To develop and validate a micro-ultrasound risk score that predicts the likelihood of significant prostate cancer in the anterior zone. METHODS: Patients were enrolled from three expert institutions familiar with micro-ultrasound. The study was conducted in two phases. First, the PRI-MUS anterior score was developed by assessing selected prostate videos from patients who subsequently underwent radical prostatectomy. Second, seven urology readers with varying levels of experience in micro-ultrasound examination evaluated prostate loops according to the PRI-MUS anterior score. Each reader watched the videos and recorded the likelihood of the presence of significant cancer in the anterior part of the prostate in a three-point scale. The coherence among the readers was calculated using the Fleiss kappa and the Cronbach alpha. RESULTS: A total of 102 selected prostate scans were used to develop the risk assessment for anterior zone cancer in the prostate. The score comprised three categories: likely, equivocal, and unlikely. The median (IQR) sensitivity, specificity, positive predictive value, and negative predictive value for the seven readers were 72% (68-84), 68% (64-84), 75% (72-81), and 73% (71-80), respectively. The mean SD ROC AUC was 0.75 ± 2%, while the Fleiss kappa and the Cronbach alpha were 0.179 and 0.56, respectively. CONCLUSION: Micro-ultrasound can detect cancerous lesions in the anterior part of the prostate. When combined with the PRI-MUS protocol to assess the peripheral part, it enables an assessment of the entire prostate gland. Pending external validation, the PRI-MUS anterior score developed in this study might be implemented in clinical practice.

Micro-ultrasound-guided biopsies versus systematic biopsies in the detection of prostate cancer: a systematic review and meta-analysis.

PURPOSE: The diagnosis of prostate cancer (PCa) still relies on the performance of both targeted (TB) and systematic biopsies (SB). Micro-ultrasound (mUS)-guided biopsies demonstrated a high sensitivity in detecting clinically significant prostate cancer (csPCa), which could be comparable to that of magnetic resonance imaging (MRI)-TB, but their added value has not been compared to SB yet. METHODS: We conducted a systematic review and meta-analysis, based on Medline, EMBASE, Scopus, and Web of Science, in accordance with PRISMA guidelines, to compare mUS-guided biopsies to SB. RESULTS: Based on the literature search of 2957 articles, 15 met the inclusion criteria (2967 patients). Most patients underwent mUS-guided biopsies, followed by MRI-TB and SB. Respectively 5 (n = 670) and 4 (n = 467) studies, providing raw data on SB, were included in a random-effect meta-analysis of the detection rate of csPCa, i.e. Gleason Grade Group (GGG) ≥ 2 or non-csPCa (GGG = 1). Overall, PCa was detected in 56-71% of men, with 31.3-49% having csPCa and 17-25.4% having non-csPCa. Regarding csPCa, mUS-guided biopsies identified 196 and SB 169 cases (Detection Ratio (DR): 1.18, 95% CI 0.83-1.68, I2 = 69%), favoring mUS-guided biopsies; regarding non-csPCa, mUS-guided biopsies identified 62 and SB 115 cases (DR: 0.55, 95% CI 0.41-0.73, I2 = 0%), also favoring mUS-guided biopsies by decreasing unnecessary diagnosis. CONCLUSION: Micro-ultrasound-guided biopsies compared favorably with SB for the detection of csPCa and detected fewer non-csPCa than SB. Prospective trials are awaited to confirm the interest of adding mUS-guided biopsies to MRI-TB to optimize csPCa detection without increasing overdiagnosis of non-csPCa.

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.

Use of high-resolution micro-ultrasound to predict extraprostatic extension of prostate cancer prior to surgery: a prospective single-institutional study.

PURPOSE: We aim to evaluate the accuracy of micro-ultrasound (microUS) in predicting extraprostatic extension (EPE) of Prostate Cancer (PCa) prior to surgery. METHODS: Patients with biopsy-proven PCa scheduled for robot-assisted radical prostatectomy (RARP) were prospectively recruited. The following MRI-derived microUS features were evaluated: capsular bulging, visible breach of the prostate capsule (visible extracapsular extension; ECE), presence of hypoechoic halo, and obliteration of the vesicle-prostatic angle. The ability of each feature to predict EPE was determined. RESULTS: Overall, data from 140 patients were examined. All predictors were associated with non-organ-confined disease (p < 0.001). Final pathology showed that 79 patients (56.4%) had a pT2 disease and 61 (43.3%) ≥ pT3. Rate of non-organ-confined disease increased from 44% in those individuals with only 1 predictor (OR 7.71) to 92.3% in those where 4 predictors (OR 72.00) were simultaneously observed. The multivariate logistic regression model including clinical parameters showed an area under the curve (AUC) of 82.3% as compared to an AUC of 87.6% for the model including both clinical and microUS parameters. Presence of ECE at microUS predicted EPE with a sensitivity of 72.1% and a specificity of 88%, a negative predictive value of 80.5% and positive predictive value of 83.0%, with an AUC of 80.4%. CONCLUSIONS: MicroUS can accurately predict EPE at the final pathology report in patients scheduled for RARP.

New imaging modalities to consider for men with prostate cancer on active surveillance.

PURPOSE: To discuss the potential utility of newer imaging modalities including micro-ultrasound and PSMA-PET for the detection of clinically significant prostate cancer, technologies that may gain roles as adjuncts to multiparametric magnetic resonance imaging (mpMRI) in the active surveillance (AS) setting. METHODS: Narrative review of two new imaging modalities used for primary prostate cancer through April 2021. A targeted search was performed to identify current relevant literature on the role of new imaging modalities for primary prostate cancer using search terms "micro-ultrasound," "molecular imaging," "prostate cancer," "active surveillance," "multiparametric MRI," "PI-RADS," "PRI-MUS," and "detection rate." In addition, references of included articles were screened for further relevant publications. RESULTS: Micro-ultrasound (micro-US) and prostate-specific membrane antigen-positron emission tomography (PSMA-PET) are increasing in their use and applicability to prostate cancer imaging. Micro-US is used for cancer detection and may identify higher grade cancers more accurately than conventional ultrasound, despite technical hurdles in its initial launch. PSMA-PET is highly sensitive and specific for high-grade and metastatic prostate cancer, though costly and not easily available. Though data are sparse, it may have an emerging role in cancer diagnosis in select localized cases, and in some men considering (or currently on) AS who have indications of more aggressive disease. CONCLUSION: There are very limited data on micro-US and PSMA-PET in AS patients. However, given the ability of these modalities to identify high-grade cancer, their judicious use in AS patients may be of utility in the future.

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.

The benefit of adopting Microultrasound in the prostate cancer imaging pathway: A lesion-by-lesion analysis: Biopsies prostatiques guidée par micro-échographie, quel bénéfice ? Une analyse lésion par lésion.

INTRODUCTION: - Microultrasound (MicroUS) is a novel imaging modality relying on a high-frequency transducer which confers a three-fold improvement in spatial resolution as compared with conventional transrectal ultrasound. We evaluated the diagnostic value of MRI-MicroUS fusion biopsy and determined the additional benefit of employing MicroUS. METHODS: - Retrospective analysis of consecutive treatment-naïve men undergoing MRI-MicroUS fusion biopsy between May 2018 and March 2019. Pre-biopsy MRI was systematically reviewed in a dedicated meeting where suspicious lesions PIRADS ≥ 3 were registered and uploaded in the ExactVu MicroUS device. MRI and MicroUS lesions were individually marked in a PIRADS v2 scheme. The biopsy protocol included MRI-MicroUS fusion and MicroUS targeted biopsies; systematic biopsies were performed at clinician's discretion. The diagnostic value was evaluated in terms of detection rate of clinically significant prostate cancer, defined as Gleason pattern ≥ 4 at histology. RESULTS: - In all, 148 patients with a median age of 69 years (IQR 63-74) and median PSA density of 0.16 ng/ml/cc (0.10-0.23) were included. Clinically significant cancer was detected in 42.5% (63/148) patients. MRI detected 89 lesions in the peripheral zone; 73% (65/89) were visible on MicroUS. Clinically significant cancer was detected in 46.1% (30/65) MRI and MicroUS visible lesions, and in 4.2% (1/24) lesions only visible on mpMRI. MicroUS additionally identified 35 suspicious lesions non-visible on MRI of which clinically significant cancer was present in 25.7% (9/35). CONCLUSION: - Adding MicroUS to the conventional pathway seems to increase the detection rate of clinically significant disease in unselected men undergoing biopsy. © 2022 Elsevier Masson SAS. All rights reserved.

WITHDRAWN: The benefit of adopting Microultrasound in the prostate cancer imaging pathway : A lesion-by-lesion analysis

INTRODUCTION: Microultrasound (MicroUS) is a novel imaging modality relying on a high-frequency transducer which confers a three-fold improvement in spatial resolution as compared with conventional transrectal ultrasound. We evaluated the diagnostic value of MRI-MicroUS fusion biopsy and determined the additional benefit of employing MicroUS. METHODS: Retrospective analysis of consecutive treatment-naïve men undergoing MRI-MicroUS fusion biopsy between May 2018 and March 2019. Pre-biopsy MRI was systematically reviewed in a dedicated meeting where suspicious lesions PIRADS≥3 were registered and uploaded in the ExactVu MicroUS device. MRI and MicroUS lesions were individually marked in a PIRADS v2 scheme. The biopsy protocol included MRI-MicroUS fusion and MicroUS targeted biopsies; systematic biopsies were performed at clinician's discretion. The diagnostic value was evaluated in terms of detection rate of clinically significant prostate cancer, defined as Gleason pattern≥4 at histology. RESULTS: In all, 148 patients with a median age of 69 years (IQR 63-74) and median PSA density of 0.16ng/ml/cc (0.10-0.23) were included. Clinically significant cancer was detected in 42.5% (63/148) patients. MRI detected 89 lesions in the peripheral zone; 73% (65/89) were visible on MicroUS. Clinically significant cancer was detected in 46.1% (30/65) MRI and MicroUS visible lesions, and in 4.2% (1/24) lesions only visible on mpMRI. MicroUS additionally identified 35 suspicious lesions non-visible on MRI of which clinically significant cancer was present in 25.7% (9/35). CONCLUSION: Adding MicroUS to the conventional pathway seems to increase the detection rate of clinically significant disease in unselected men undergoing biopsy.

Advanced ultrasound in the diagnosis of prostate cancer.

The diagnosis of prostate cancer (PCa) can be challenging due to the limited performance of current diagnostic tests, including PSA, digital rectal examination and transrectal conventional US. Multiparametric MRI has improved PCa diagnosis and is recommended prior to biopsy; however, mp-MRI does miss a substantial number of PCa. Advanced US modalities include transrectal prostate elastography and contrast-enhanced US, as well as improved B-mode, micro-US and micro-Doppler techniques. These techniques can be combined to define a novel US approach, multiparametric US (mp-US). Mp-US improves PCa diagnosis but is not sufficiently accurate to obviate the utility of mp-MRI. Mp-US using advanced techniques and mp-MRI provide complementary information which will become even more important in the era of focal therapy, where precise identification of PCa location is needed.

Impact of using 29 MHz high-resolution micro-ultrasound in real-time targeting of transrectal prostate biopsies: initial experience.

PURPOSE: This report presents our early experience at Cleveland Clinic replacing conventional ultrasound with a novel 29 MHz high-resolution micro-ultrasound system for both systematic sampling and real-time targeting of suspicious regions during prostate biopsy. The added value of micro-ultrasound and MRI over systematic biopsy is presented. METHODS: Sixty-seven consecutive subjects (January-August 2018) from our prospective database who underwent prostate biopsy using the micro-ultrasound system were included. 19/67 had prostate MRI imaging available. MRI targets were sampled using the UroNav fusion system. Patients had a median PSA of 5.37 ng/mL (IQR 4.13-8.74). RESULTS: 38/67 (56.7%) subjects were positive for prostate cancer. In six of these cases, systematic biopsy was negative with only micro-ultrasound targeted samples detecting cancer. In two other cases, patients were upgraded from Grade Group 1 to Grade Groups 4 and 2 based on micro-ultrasound targets. Micro-ultrasound targets detected cancer in two subjects where MRI was negative (Grade Groups 3 and 2). MRI targets alone did not change the overall diagnosis of any subjects. Switching biopsy guidance to real-time micro-ultrasound increased detection rate on prostate biopsy from 44.8% (30/67) to 56.7% (38/67), a relative increase of 26.7%. CONCLUSION: High-resolution micro-ultrasound identified clinically significant cancer that would have, otherwise, been missed by both MRI fusion and systematic biopsy and was useful in both biopsy naïve and repeat negative patients. Early results from this small, single-center cohort are promising, particularly given the ease with which micro-ultrasound can replace the conventional ultrasound in standard prostate biopsy procedures.

Fluorescence labeled microbubbles for multimodal imaging.

Air-filled polyvinyl alcohol microbubbles (PVA-MBs) were recently introduced as a contrast agent for ultrasound imaging. In the present study, we explore the possibility of extending their application in multimodal imaging by labeling them with a near infrared (NIR) fluorophore, VivoTag-680. PVA-MBs were injected intravenously into FVB/N female mice and their dynamic biodistribution over 24 h was determined by 3D-fluorescence imaging co-registered with 3D-µCT imaging, to verify the anatomic location. To further confirm the biodistribution results from in vivo imaging, organs were removed and examined histologically using bright field and fluorescence microscopy. Fluorescence imaging detected PVA-MB accumulation in the lungs within the first 30 min post-injection. Redistribution to a low extent was observed in liver and kidneys at 4 h, and to a high extent mainly in the liver and spleen at 24 h. Histology confirmed PVA-MB localization in lung capillaries and macrophages. In the liver, they were associated with Kupffer cells; in the spleen, they were located mostly within the marginal-zone. Occasional MBs were observed in the kidney glomeruli and interstitium. The potential application of PVA-MBs as a contrast agent was also studied using ultrasound (US) imaging in subcutaneous and orthotopic pancreatic cancer mouse models, to visualize blood flow within the tumor mass. In conclusion, this study showed that PVA-MBs are useful as a contrast agent for multimodal imaging.

Micro-ultrasound based characterization of cerebrovasculature following focal ischemic stroke and upon short-term rehabilitation.

Notwithstanding recanalization treatments in the acute stage of stroke, many survivors suffer long-term impairments. Physical rehabilitation is the only widely available strategy for chronic-stage recovery, but its optimization is hindered by limited understanding of its effects on brain structure and function. Using micro-ultrasound, behavioral testing, and electrophysiology, we investigated the impact of skilled reaching rehabilitation on cerebral hemodynamics, motor function, and neuronal activity in a rat model of focal ischemic stroke. A 50 MHz micro-ultrasound transducer and intracortical electrophysiology were utilized to characterize neurovascular changes three weeks following focal ischemia elicited by endothelin-1 injection into the sensorimotor cortex. Sprague-Dawley rats were rehabilitated through tray reaching, and their fine skilled reaching was assessed via the Montoya staircase. Focal ischemia led to a sustained deficit in forelimb reaching; and increased tortuosity of the penetrating vessels in the perilesional cortex; with no lateralization of spontaneous neuronal activity. Rehabilitation improved skilled reaching; decreased cortical vascularity; was associated with elevated peri- vs. contralesional hypercapnia-induced flow homogenization and increased perilesional spontaneous cortical neuronal activity. Our study demonstrated neurovascular plasticity accompanying rehabilitation-elicited functional recovery in the subacute stage following stroke, and multiple micro-ultrasound-based markers of cerebrovascular structure and function modified in recovery from ischemia and upon rehabilitation.

MicroSegNet: A deep learning approach for prostate segmentation on micro-ultrasound images.

Micro-ultrasound (micro-US) is a novel 29-MHz ultrasound technique that provides 3-4 times higher resolution than traditional ultrasound, potentially enabling low-cost, accurate diagnosis of prostate cancer. Accurate prostate segmentation is crucial for prostate volume measurement, cancer diagnosis, prostate biopsy, and treatment planning. However, prostate segmentation on micro-US is challenging due to artifacts and indistinct borders between the prostate, bladder, and urethra in the midline. This paper presents MicroSegNet, a multi-scale annotation-guided transformer UNet model designed specifically to tackle these challenges. During the training process, MicroSegNet focuses more on regions that are hard to segment (hard regions), characterized by discrepancies between expert and non-expert annotations. We achieve this by proposing an annotation-guided binary cross entropy (AG-BCE) loss that assigns a larger weight to prediction errors in hard regions and a lower weight to prediction errors in easy regions. The AG-BCE loss was seamlessly integrated into the training process through the utilization of multi-scale deep supervision, enabling MicroSegNet to capture global contextual dependencies and local information at various scales. We trained our model using micro-US images from 55 patients, followed by evaluation on 20 patients. Our MicroSegNet model achieved a Dice coefficient of 0.939 and a Hausdorff distance of 2.02 mm, outperforming several state-of-the-art segmentation methods, as well as three human annotators with different experience levels. Our code is publicly available at https://github.com/mirthAI/MicroSegNet and our dataset is publicly available at https://zenodo.org/records/10475293.

Inter-reader Agreement for Prostate Cancer Detection Using Micro-ultrasound: A Multi-institutional Study.

Background and objective: Micro-ultrasound (MUS) uses a high-frequency transducer with superior resolution to conventional ultrasound, which may differentiate prostate cancer from normal tissue and thereby allow targeted biopsy. Preliminary evidence has shown comparable sensitivity to magnetic resonance imaging (MRI), but consistency between users has yet to be described. Our objective was to assess agreement of MUS interpretation across multiple readers. Methods: After institutional review board approval, we prospectively collected MUS images for 57 patients referred for prostate biopsy after multiparametric MRI from 2022 to 2023. MUS images were interpreted by six urologists at four institutions with varying experience (range 2-6 yr). Readers were blinded to MRI results and clinical data. The primary outcome was reader agreement on the locations of suspicious lesions, measured in terms of Light's κ and positive percent agreement (PPA). Reader sensitivity for identification of grade group (GG) ≥2 prostate cancer was a secondary outcome. Key findings and limitations: Analysis revealed a κ value of 0.30 (95% confidence interval [CI] 0.21-0.39). PPA was 33% (95% CI 25-42%). The mean patient-level sensitivity for GG ≥2 cancer was 0.66 ± 0.05 overall and 0.87 ± 0.09 when cases with anterior lesions were excluded. Readers were 12 times more likely to detect higher-grade cancers (GG ≥3), with higher levels of agreement for this subgroup (κ 0.41, PPA 45%). Key limitations include the inability to prospectively biopsy reader-delineated targets and the inability of readers to perform live transducer maneuvers. Conclusions and clinical implications: Inter-reader agreement on the location of suspicious lesions on MUS is lower than rates previously reported for MRI. MUS sensitivity for cancer in the anterior gland is lacking. Patient summary: The ability to find cancer on imaging scans can vary between doctors. We found that there was frequent disagreement on the location of prostate cancer when doctors were using a new high-resolution scan method called micro-ultrasound. This suggests that the performance of micro-ultrasound is not yet consistent enough to replace MRI (magnetic resonance imaging) for diagnosis of prostate cancer.

A current role status of micro-ultrasound imaging in prostate cancer diagnosis.

 Recently diagnostic field in medicine was enriched by advances in ultrasonography (US) technology, which led to establishment of novel modalities, one of which is micro-ultrasound. Results demonstrated by early studies have been promising, simultaneously rising a question if those new modalities could become an alternative in diagnosis of prostatic carcinoma (PCa). To answer this question, several studies have been conducted where micro-ultrasound have been compared to standard diagnostic tools, such as conventional TRUS or mpMRI. Nevertheless, new technology presents with some limitations, which include inconsistent results, necessity for specialized equipment, need of training for investigators to understand the findings, and external validation. In this publication, we have identified studies that provided evaluation of the accuracy and efficiency of the micro-ultrasound technology. Additionally, analysis of the results provided a better understanding of the novel imaging tool when compared standard modalities in diagnosis of PCa. Increasing number of studies demonstrated that micro-ultrasound carries high detection rate of PCa and clinically significant prostatic cancer (csPCa), suggesting a similar performance to mpMRI and even showing superiority over conventional TRUS. Recent studies have also showed that micro-ultrasound takes active role in improving the detection of csPCa and guidance for prostate biopsy (PBx) as well as further treatment. Moreover, certain practical aspects such as lower costs, decreased waiting time, real-time imaging and application of the imaging tool for patients that are not suitable for mpMRI (contrast allergy, prosthetics etc.) are significant advantages. Analysis of the results still does not provide clear answer whether micro-ultrasound outperforms mpMRI. Further studies are necessary in order to completely understand the potential of this new technology.

Evaluation of prostate cancer detection using micro-ultrasound versus MRI through co-registration to whole-mount pathology.

Micro-ultrasound has recently been introduced as a low-cost alternative to multi-parametric MRI for imaging prostate cancer. Early clinical studies have demonstrated promising results; however, robust validation via comparison with whole-mount pathology has yet to be achieved. Due to micro-ultrasound probe design and tissue deformation during scanning, it is difficult to accurately correlate micro-ultrasound imaging planes with ground truth whole-mount pathology slides. In this study, we developed a multi-step methodology to co-register micro-ultrasound and MRI to whole-mount pathology. The three-step process had a registration error of 3.90 ± 0.11 mm and consists of: (1) micro-ultrasound image reconstruction, (2) 3D landmark registration of micro-ultrasound to MRI, and (3) 2D capsule registration of MRI to whole-mount pathology. This process was then used in a preliminary reader study to compare the diagnostic accuracy of micro-ultrasound and MRI in 15 patients who underwent radical prostatectomy for prostate cancer. Micro-ultrasound was found to have equivalent performance to retrospective MRI review for index lesion detection (91.7% vs. 80%), while demonstrating an increased detection of tumor extent (52.5% vs. 36.7%) with similar false positive regions-of-interest (38.3% vs. 40.8%). Prospective MRI review had reduced detection of index lesions (73.3%) and tumor extent (18.9%) but improved false positive regions-of-interest (22.7%) relative to micro-ultrasound and retrospective MRI. Further evaluation is needed with a larger sample size.