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1901. MR-Guided Transgluteal Prostate Biopsy of PIRADS 4 and 5 Lesions
Authors * Denotes Presenting Author
  1. Guenther Schneider *; Saarland University Medical Center
  2. Tobias Woerner; Saarland University Medical Center
  3. Arno Buecker; Saarland University Medical Center
Objective:
The initial indication for transgluteal biopsy of the prostate in our institution was in patients post rectal surgery in which rectal ultrasound for guidance of prostate biopsy wasn't possible and at least one PIRADS 4 or 5 lesion was detected on multi parametric prostate MRI. However, since this method offers the advantage of the use of a coaxial core-biopsy system together with an optimal depiction of the biopsy target and no need for additional hardware, we started to use the transgluteal approach routinely on a 3T system (VIDA, Siemens, Germany) in biopsy of PIRADS 4/5 lesions. The purpose of our study was to prospectively evaluate transgluteal prostate biopsy in evaluation of PIRADS 4 and 5 lesions.

Materials and Methods:
Biopsy was performed with the patient in prone position covered by a phase array coil in which sufficient large holes are available to perform the biopsy. No sedation was necessary in any of our patients. In a total of 28 patients (age range 52-74) at least one targeted biopsy and up to a total of 20 biopsies including targeted and systematic biopsies were performed. After local anesthesia a 20G coaxial needle was forwarded to the target area of the prostate and subsequently two to three biopsies (18G) from the PIRADS 4/5 area were sampled. Sequences used during positioning of the needle were single shot HASTE sequences followed by a T2w TSE sequences to confirm exact positioning of the coaxial needle. In case of additional systematic biopsies the coaxial needle was then repositioned towards the base, middle and apex of the prostate and biopsies with a length of approx. 2.5 cm were acquired at each level medial and lateral covering the prostate tissue uniformly. This was afterwards repeated on the contralateral side. When the coaxial needle was removed the biopsy tract was sealed with gelatin foam pledges to facilitate hemostasis and to avoid contamination of surrounding tissue by tumor cells. Following the biopsy T1w and T2w TSE scans were performed to document the biopsy areas.

Results:
In non of our patients complications as bleeding, infection or abscess formation were observed. Only minor hematuria was reported in 21 of 28 patients. All tissue samples were applicable for analysis. Targeted biopsies revealed Gleason-Scores between 6 and 8 in 19 out of 28 patients, in 9 patients chronic prostatitis including 3 cases of granulomatous prostatitis were diagnosed. In 7/28 patients, in which additional systematic biopsies were performed, Gleason 6 lesions were found in 4 patients, in one patient a Gleason 7 lesion was diagnosed. In the remaining cases chronic prostatitis, hyperplasia or normal prostatic tissue were found on histology.

Conclusion:
MR guided transgluteal biopsy of PIRADS 4 / 5 lesions is a safe and efficient method which can be performed as an outpatient procedure without the need of patient sedation. In contrast to transrectal biopsy, no risk of infection is apparent due to a steril biopsy approach and so no antibiotic prophylaxis was performed. Correct sampling of tissue form the targeted PIRADS lesion can be documented and sampling errors can be avoided.