Accuracy of MRI-ultrasound fusion-guided and systematic biopsy of the prostate

Abstract

Objectives: Prostate multiparametric MRI (mpMRI) with subsequent targeted biopsy of suspicious lesions has a critical role in the diagnostic workup of prostate cancer. The objective was to evaluate the diagnostic accuracy of systematic biopsies, targeted biopsies, and the combination of both in prostate cancer detection.

Methods: From January 1, 2013 to June 1, 2022, biopsy-naïve and prior biopsy-negative patients who underwent both systematic and targeted biopsies were included. MRIs were evaluated according to PI-RADS with biopsy threshold set at PI-RADS ≥3. Systematic biopsies consisted of 8-12 cores, based on prostate volume. Overall prostate cancer and clinically significant cancer (Gleason Score ≥3 + 4) detection rates were stratified based on PI-RADS and location within the prostate, and compared between biopsy types using McNemar test.

Results: Among 867 patients, 615 had prostate cancer, with 434 clinically significant cases. Overall detection rates were: PI-RADS 3 48%, PI-RADS 4 72%, and PI-RADS 5 90%. Detection rates for clinically significant cancer were 21%, 53%, and 72%, respectively. The combination of biopsy methods was most accurate in detecting clinically significant prostate cancer (P < .001). Targeted biopsies alone detected more clinically significant prostate cancer than systematic biopsies alone (43.1% vs 40.3%, P = .046). For posterior PI-RADS 5 lesions, no statistically significant difference was found between all biopsy methods.

Conclusions: In the detection of clinically significant prostate cancer, the combination of systematic and targeted biopsies proves most effective. Targeted biopsies rarely missed significant cancer for posterior PI-RADS 5 lesions, suggesting systematic biopsies could be reserved for instances where targeted biopsy results are negative.

Advances in knowledge: This study emphasizes on the efficacy of mpMRI and targeted biopsies in suspected prostate cancer in real-world clinical context. For PI-RADS 5 lesions, systematic biopsies provide limited clinical benefit and may only be necessary when targeted biopsy results are negative.

Keywords: MRI-ultrasound fusion biopsy; PI-RADS; biopsy-naïve; prior biopsy negative; prostate cancer; systematic biopsy; targeted biopsy.

Figure 1.

Detection rate of prostate cancer with proportion of clinically significant prostate cancer among PI-RADS categories per biopsy approach in biopsy-naive and prior biopsy-negative patients (CB = combined biopsy method; CDR = cancer detection rate; csPCa = clinically significant prostate cancer; cisPCa = clinically insignificant prostate cancer; TB = targeted biopsy; SB = systematic biopsy).

Figure 2.

Case example of a 73-year-old biopsy-naïve patient, who presented with normal digital rectal exam and elevated PSA value of 8.6 ng/mL. Axial T2-weighted imaging shows a left-sided moderately hypointense lesion of 2.7 cm, located in the anterior fibromuscular stroma and anterior transition zone of the mid portion of the prostate (A). The lesion shows marked hyperintensity on diffusion-weighted imaging (B) and marked hypointensity on ADC image (C). Final PI-RADS category was 5, based on the dominant T2-weighted sequence. Systematic biopsy yielded insignificant cancer with a Gleason score of 3 + 3 = 6, while targeted biopsy of the anteriorly located PIRADS 5 lesion contained significant cancer with Gleason score of 4 + 4 = 8. The patient received radical prostatectomy.