Number of cores needed to diagnose prostate cancer during MRI targeted biopsy decreases after the learning curve

Enhancing Prostate Cancer Detection Accuracy in Magnetic Resonance Imaging-targeted Prostate Biopsy: Optimizing the Number of Cores Taken

Background and objective

The shift toward targeted biopsy (TBx) aims at enhancing prostate cancer (PCa) detection while reducing overdiagnosis of clinically insignificant disease. Despite the improved ability of TBx in identifying clinically significant PCa (csPCa), the optimal number and location of targeted cores remain unclear. This review aims to assess the optimal number of prostate biopsy magnetic resonance imaging (MRI)-targeted cores to detect csPCa.

Methods

A narrative literature search was conducted using PubMed, focusing on studies published between January 2014 and January 2024, addressing factors influencing targeted core numbers during prostate biopsy. The search included both retrospective and prospective studies, prioritizing those with substantial sample sizes and employing terms such as "prostate biopsy", "mpMRI", "core number", and "cancer detection".

Key findings and limitations

Two biopsy cores identified csPCa in 55-65% of cases. This detection rate improved to approximately 90% when the number of cores was ≥5. The inclusion of perilesional and systematic biopsies could maximize the detection of csPCa (from 10% to 45%), especially in patients under active surveillance or with prior negative biopsy results, although there is an increase in the overdiagnosis of indolent tumors (from 4% to 20%). Transperineal software-assisted target prostate biopsy may enhance cancer detection, particularly for tumors located at the apex/anterior part of the prostate. Increasing the number of TBx cores may incrementally raise the risk of complications (by 2-14% with each added core) and result in severe pain and significant discomfort for up to 17% and 25% of TBx patients, respectively. However, the overall rate and severity of these complications remain within acceptable limits.

Conclusions and clinical implications

The optimal number of cores for targeted prostate biopsies should balance minimizing sampling errors with effective cancer detection and should be tailored to each patient's unique prostate characteristics. Up to five cores per MRI target may be considered to enhance the detection of csPCa, with adjustments based on factors such as prostate and lesion volume, Prostate Imaging Reporting and Data System, biopsy techniques, complications, patient discomfort, and anxiety.

Patient summary

In this report, we found that increasing the number of biopsy cores up to ≥5 improves the detection rates of significant prostate cancer significantly to around 90%. Although inclusion of nearby and systematic biopsies enhances detection, increasing the biopsy count may lead to higher risks of complications and indolent tumors. A customized biopsy approach based on multiple variables could be helpful in determining the appropriate number of targeted biopsies on a case-by-case basis.

Does a large prostate size, small lesion volume, or long needle distance from the probe to the lesion reduce magnetic resonance imaging-targeted cancer detection?

Background

We aimed to evaluate whether large prostate size, small lesion volume, or long lesion distance from the ultrasound probe tip would decrease cancer detection in transrectal magnetic resonance imaging (MRI)-targeted biopsies.

Materials and methods

Patients who underwent MRI-targeted biopsy at our institution between May 2017 and August 2019 were enrolled in a prospective database. Three to 5 cores were obtained from ≥2 prostate imaging reporting and data system v2 lesions. A multivariable model was created that included needle distance to the lesion, prostate specific antigen, prostate imaging reporting and data system, lesion volume, and prostate volume.

Results

A total of 377 patients with 533 lesions underwent a biopsy during the study period. A total of 233 (44%) lesions were positive for prostate cancer, and 173 (32%) lesions had clinically significant prostate cancer. The mean needle distance to the lesion was 11.7 mm (interquartile range, 7.6-15.5 mm). The likelihood of obtaining a positive core on biopsy decreased as the distance from the ultrasound probe increased for all prostate cancers and clinically significant prostate cancer (p = 0.018 and p = 0.004, respectively). Every 10 mm from the rectum, there was an 8%-10% decrease in the rate of cancer detection. Similarly, as the prostate volume increased, the odds of obtaining a positive core also decreased (p = 0.039). There was no significant association between the lesion size and amount of cancer obtained on biopsy.

Conclusions

Our data showed that transrectal MRI-targeted biopsy cancer detection modestly decreased the lesion from the ultrasound probe and with a large prostate volume but could not prove that lesion volume was a significant predictor of the amount of cancer detected.

MRI-informed prostate biopsy: What the radiologist should know on quality in biopsy planning and biopsy acquisition

Quality is currently recognized as the pre-requisite for delivering the clinical benefits expected by magnetic resonance imaging (MRI)-informed prostate biopsy (MRI-i-PB) in patients with a suspicion for clinically significant prostate cancer (csPCa). The "quality chain" underlying MRI-i-PB is multidisciplinary in nature, and depends on several factors related to the patient, imaging technique, image interpretation and biopsy procedure. This review aims at making the radiologist aware of biopsy-related factors impacting on MRI-i-PB quality, both in terms of biopsy planning (threshold for biopsy decisions, association with systematic biopsy and number of targeted cores) and biopsy acquisition (biopsy route, targeting technique, and operator's experience). While there is still space for improvement and better standardization of several biopsy-related procedures, current evidence suggests that high-quality MRI-i-PB can be delivered by acquiring and increased the number of biopsy cores targeted to suspicious imaging findings and perilesional area ("focal saturation biopsy"). On the other hand, uncertainty still exists as to whether software-assisted fusion of MRI and transrectal ultrasound images can outperform cognitive fusion strategy. The role for operator's experience and quality assurance/quality control procedures are also discussed.

Optimizing multiparametric magnetic resonance imaging-targeted biopsy and detection of clinically significant prostate cancer: the role of core number and location

PURPOSE

There is currently no consensus regarding the optimal number of multiparametric magnetic resonance imaging (MRI)-targeted biopsy (TB) cores and their spatial distribution within the MRI lesion. We aim to determine the number of TB cores and location needed to adequately detect csPCa.

METHODS

We conducted a retrospective cohort study of 505 consecutive patients undergoing TB for positive MRI lesions defined by a PI-RADS score ≥ 3 between June 2016 and January 2022. Cores chronology and locations were prospectively recorded. The co-primary outcomes were the first core to detect clinically significant prostate cancer (csPCa) and the first highest ISUP grade group. The incremental benefit of each additional core was evaluated. Analysis was then performed by distinguishing central (cTB) and peripheral (pTB) within the MRI lesion.

RESULTS

Overall, csPCa was detected in 37% of patients. To reach a csPCa detection rate of 95%, a 3-core strategy was required, except for patients with PI-RADS 5 lesions and those with PSA density ≥ 0.2 ng/ml/cc who benefited from a fourth TB core. At multivariable analysis, only a PSA density ≥ 0.2 ng/ml/cc was an independent predictive factor of having the highest ISUP grade group on the fourth TB cores (p = 0.03). No significant difference in the cancer detection rate was found between cTB and pTB (p = 0.9). Omitting pTB would miss 18% of all csPCa.

CONCLUSION

A 3-core strategy should be considered for TB to optimize csPCa detection with additional cores needed for PI-RADS 5 lesions and high PSA density. Biopsy cores from both central and peripheral zones are required.

Quality checkpoints in the MRI-directed prostate cancer diagnostic pathway

Multiparametric MRI of the prostate is now recommended as the initial diagnostic test for men presenting with suspected prostate cancer, with a negative MRI enabling safe avoidance of biopsy and a positive result enabling MRI-directed sampling of lesions. The diagnostic pathway consists of several steps, from initial patient presentation and preparation to performing and interpreting MRI, communicating the imaging findings, outlining the prostate and intra-prostatic target lesions, performing the biopsy and assessing the cores. Each component of this pathway requires experienced clinicians, optimized equipment, good inter-disciplinary communication between specialists, and standardized workflows in order to achieve the expected outcomes. Assessment of quality and mitigation measures are essential for the success of the MRI-directed prostate cancer diagnostic pathway. Quality assurance processes including Prostate Imaging-Reporting and Data System, template biopsy, and pathology guidelines help to minimize variation and ensure optimization of the diagnostic pathway. Quality control systems including the Prostate Imaging Quality scoring system, patient-level outcomes (such as Prostate Imaging-Reporting and Data System MRI score assignment and cancer detection rates), multidisciplinary meeting review and audits might also be used to provide consistency of outcomes and ensure that all the benefits of the MRI-directed pathway are achieved.

Single center analysis of an advisable control interval for follow-up of patients with PI-RADS category 3 in multiparametric MRI of the prostate

To evaluate if follow-up mpMRI scans of patients in PI-RADS category 3 are safe enough to omit or delay prostate biopsy in the future and to determine an optimal control interval. This retrospective single center study includes consecutive PI-RADS category 3 patients with one or more follow-up mpMRI (T2WI, DWI, DCE) and subsequent MRI-targeted and systematic TRUS-guided biopsy between 2012 and 2018. Primary study objective was the verification of a significant PI-RADS category upgrade in follow-up mpMRI in patients with subsequent PCA positive biopsy versus patients with negative biopsy. Further objectives were development of the PI-RADS category and clinical parameters between initial and follow-up mpMRI in the context of histopathologic results and time interval. Eighty-nine patients (median PSA 6.6 ng/ml; PSAD 0.13 ng/ml/ml) were finally included (follow-up period 31 ± 18 months). 19 cases had PCA (median PSA 7.8 ng/ml; PSAD 0.14 ng/ml/ml). 4 cases had csPCA (median PSA 5.4 ng/ml; PSAD 0.13 ng/ml/ml) for which there was a significant PI-RADS upgrade after 12-24 months (mean 3.75; p = 0.01) compared to patients without PCA (mean 2.74). Without PCA the mean PI-RADS category decreased after 25-36 months (mean 2.74; p = 0.02). Clinical parameters did not change significantly except a PSAD increase for PCA patients after 24 months. Patients within PI-RADS category 3 may not need prompt biopsy since those with PCA reliably demonstrate a PI-RADS category upgrade in follow-up mpMRI after 12-24 months. PI-RADS 3 patients with negative biopsy do not benefit from follow-up mpMRI earlier than 24 months.