Why Does Magnetic Resonance Imaging-Targeted Biopsy Miss Clinically Significant Cancer?

Abstract

Purpose: Multiple studies demonstrate magnetic resonance imaging (MRI)-targeted biopsy detects more clinically significant cancer than systematic biopsy; however, some clinically significant cancers are detected by systematic biopsy only. While these events are rare, we sought to perform a retrospective analysis of these cases to ascertain the reasons that MRI-targeted biopsy missed clinically significant cancer which was subsequently detected on systematic prostate biopsy.

Materials and methods: Patients were enrolled in a prospective study comparing cancer detection rates by transrectal MRI-targeted fusion biopsy and systematic 12-core biopsy. Patients with an elevated prostate specific antigen (PSA), abnormal digital rectal examination, or imaging findings concerning for prostate cancer underwent prostate MRI and subsequent MRI-targeted and systematic biopsy in the same setting. The subset of patients with grade group (GG) ≥3 cancer found on systematic biopsy and GG ≤2 cancer (or no cancer) on MRI-targeted biopsy was classified as MRI-targeted biopsy misses. A retrospective analysis of the MRI and MRI-targeted biopsy real-time screen captures determined the cause of MRI-targeted biopsy miss. Multivariable logistic regression analysis compared baseline characteristics of patients with MRI-targeted biopsy misses to GG-matched patients whose clinically significant cancer was detected by MRI-targeted biopsy.

Results: Over the study period of 2007 to 2019, 2,103 patients met study inclusion criteria and underwent combined MRI-targeted and systematic prostate biopsies. A total of 41 (1.9%) men were classified as MRI-targeted biopsy misses. Most MRI-targeted biopsy misses were due to errors in lesion targeting (21, 51.2%), followed by MRI-invisible lesions (17, 40.5%) and MRI lesions missed by the radiologist (3, 7.1%). On logistic regression analysis, lower Prostate Imaging-Reporting and Data System (PI-RADS^TM) score was associated with having clinically significant cancer missed on MRI-targeted biopsy.

Conclusions: While uncommon, most MRI-targeted biopsy misses are due to errors in lesion targeting, which highlights the importance of accurate co-registration and targeting when using software-based fusion platforms. Additionally, some patients will harbor MRI-invisible lesions which are untargetable by MRI-targeted platforms. The presence of a low PI-RADS score despite a high PSA is suggestive of harboring an MRI-invisible lesion.

Keywords: biopsy; diagnosis; multiparametric magnetic resonance imaging; prostatic neoplasms.

Figure 1.

Multiparametric MRI image example of clinically significant cancer that was missed due to MRI-targeted biopsy targeting error. 56-year-old male with a serum PSA of 5.9ng/ml. Axial T2-Weighted (T2W) MRI shows a hypointense lesion in the right mid-peripheral zone (arrow) (A), the lesion shows diffusion restriction on ADC map (B) and b2000 DW MRI (C) and early enhancement on DCE MRI (D) (arrows). Targeted biopsy revealed Gleason 3+4 prostate cancer in this lesion, whereas systematic biopsy yielded Gleason 4+4 prostate adenocarcinoma in the right peripheral zone. (E) Screen captures of the TRUS/MRI fusion guided biopsy procedure (E) demonstrates a registration error between MRI (inked in red) vs. TRUS (inked in dashed yellow), which is likely the reason for the under-sampling of the right mid peripheral zone lesion during TRUS/MRI fusion guided biopsy.

Figure 2.

Multiparametric MRI image example of clinically significant cancer missed by initial radiologist read. 71-year-old male with a serum PSA of 14.2ng/ml. Axial T2W MRI shows a hypointense lesion in the right apical peripheral zone (arrow) (A), the lesion shows diffusion restriction on ADC map (B) and b2000 DW MRI (C) and early enhancement on DCE MRI (D) (arrows). This lesion was not reported in the prospective radiology read-out, however systematic biopsy yielded Gleason 4+3 prostate adenocarcinoma in the right apical peripheral zone.

Figure 3.

Multiparametric MRI image example of clinically significant cancer that was MRI-invisible. 72-year-old male with a serum PSA of 6.55ng/ml. Systematic biopsy revealed Gleason 4+4 prostate adenocarcinoma in the right base lateral region of the prostate, however axial T2W MRI (A), ADC map (B), b2000 DW MRI (C) and DCE MRI (D) does not demonstrate an MRI visible disease focus in the right base of the prostate. systematic biopsy yielded Gleason 4+3 prostate adenocarcinoma in the right apical peripheral zone.

Figure 4.

Proportion of each reason for MRI-targeted biopsy missing clinically significant cancer