Analyzing the Learning Curve for MRI-transrectal Ultrasonography Fusion-guided Transrectal Prostate Biopsy: Beyond the Abstract

Fusion of MRI and transrectal ultrasonography (TRUS) of the prostate has played an increasing role in detection of prostate cancer in the past few years. 

In addition, the application of this new technique currently expands into monitoring of active surveillance and focal therapy. Consequently, we are faced with a growing demand for urologists trained in performing MRI/TRUS fusion biopsies in our own department and we assumed that other institutions might share this experience. 

Particularly if an electromagnetic tracking platform with freehand positioning of the transrectal end-fire ultrasonography probe is used, biopsy accuracy is assumed to be highly influenced by the urologist’s level of training. Nevertheless, little is known about the learning progress necessary to achieve both accuracy and efficiency of MRI/TRUS fusion transrectal biopsies.

Thus, we retrospectively analyzed all MRI/TRUS fusion biopsies performed by a novice to evaluate his learning curve.  Learning progress was measured by calculation of the detection quotient in the subset of targeted biopsy cores in procedures uncovering prostate cancer. If 2 of 4 targeted biopsy cores were positive for cancer, detection quotient would be 0.5. 

The advantage of implementing this quotient was to exclude biopsy procedures of possible true negative prostates from analysis. The disadvantage was that all biopsy procedures without detection of prostate cancer were omitted from this analysis. In contrast, addressing the procedural efficiency by investigating the biopsy time, all procedures were available for analysis. In this way we unveiled the novice’s learning curve over 84 biopsy procedures. Interestingly, achieving significant learning progress needed much more biopsy procedures than we initially assumed. 

Taken together, we added insight into the urologist’s learning curve of MRI transrectal end-fire ultrasonography fusion biopsy. Clinical implications of our study might include the novice’s supervision by an expert beyond learning curve while passing MRI/TRUS fusion biopsy technique onto the next generation.

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Written By: Rene Mager