Fusion prostate biopsy: tips and tricks to improve rigid registration

Abstract

Background: We introduced tips and tricks to improve the rate of correct rigid registration during fusion prostate biopsy: (1) creation of similar anatomical condition during multiparametric magnetic resonance of the prostate (mpMRI) and trans rectal ultrasound (TRUS) (bladder and rectum should be empty and the use of MRI trans rectal probe avoided), (2) revision of mpMRI performed outside our institution by our radiologist, (3) the use of the boundary between transitional/central and peripheral zone of the prostate as the main anatomical landmark (less prone than the peripheral shape to deformation) at the level of the target, (4) repeating the registration at the level of every target or after unintended movement of the patients. Methods: We reviewed our internal database to assess the impact of our tips and tricks. Patients submitted to radical prostatectomy after fusion biopsy in our centre over the last two years were selected. Biopsy positivity in a sextant with cancer at the radical prostatectomy and a suspected mpMRI (3–5) was computed as a correct registration, the positivity of a biopsy in an adjacent sextant as a quasi-correct registration. Results: 49 out of 59 and 5 out 59 correct and quasi-correct registrations were finally computed. Assuming acceptable 90% of correct and 95% of quasi-correct rate, the expected figures are respectively 53 and 3. The chi-square goodness of fit test show a X square value of 2.97 and a p-value of 0.23. Therefore, the null hypothesis that the two distributions are homogeneous cannot be rejected. Conclusions: The introduction of some tips and trick in the daily clinical practice contributed to some extent to a satisfactory rate of correct rigid registration in our series of fusion prostate biopsies.