RADIOLOGY CORNER MRI-guided Salvage Cryoablation of Postprostatectomy Seminal Vesicle Bed Recurrence

By: Derek Lomas, MD, Mayo Clinic, Rochester, Minnesota; David Woodrum, MD, PhD, Mayo Clinic, Rochester, Minnesota; Lance Mynderse, MD, Mayo Clinic, Rochester, Minnesota | Posted on: 20 Jul 2023

A 75-year-old male was initially diagnosed with Gleason 4 + 3 = 7 prostate cancer and treated with robot-assisted radical prostatectomy. He subsequently underwent salvage radiation secondary to rising PSA with initial response. Unfortunately, his PSA subsequently rose to 4.4 ng/mL and hormone treatment was recommended by local providers. The patient wanted to avoid hormone therapy. The patient was referred for additional treatment discussion. Metastatic workup with gallium 68 prostate-specific membrane antigen positron emission tomography MRI demonstrated findings concerning for seminal vesicle bed recurrence without evidence of metastatic disease (Figure 1). An in-bore MRI-guided biopsy of the seminal vesicle beds demonstrated Gleason 4 + 4 = 8 prostate cancer in the right bed and benign findings from the left seminal vesicle bed (Figure 2).

Figure 1. Gallium 68 prostate-specific membrane antigen positron emission tomography MRI showing suspicious lesion in right seminal vesicle bed (white arrows). A, T2-weighted imaging. B, Dynamic contrast-enhanced MRI. C, Fused positron emission tomography/MRI.
Figure 2. In-bore MRI-guided biopsy of the prostate fossa. Yellow arrows show biopsy needle locations in the right (Biopsy A2) and left (Biopsy B2) seminal vesicle beds.

MRI-guided salvage cryoablation of the right seminal vesicle bed recurrence was offered. MRI-guided cryoablation was performed using our previously described method.1 The patient was placed under general anesthesia and positioned on the MRI table in a semi-frogleg supine position. A guidance grid was positioned against the perineum for transperineal placement of magnetic resonance–compatible cryoprobes.

The proximity of the rectum to the ablation zone can pose a challenge during cryoablation and predispose patients to rectal complications. To increase the distance from the targeted ablation zone and the rectum, saline can be infused transperineally to move and protect the rectum. To perform this, a 14F infusion cannula was placed transperineally under magnetic resonance guidance and sterile normal saline infused via pressure bag.2 Figure 3 shows the degree of rectal movement that was achieved.

Figure 3. MRIs demonstrating saline displacement. A, Pretreatment imaging. B, Imaging after saline displacement. C, Intraprocedural imaging highlighting approximate area of infused saline (blue dashed line) and displaced rectum (red dashed line).

Due to the proximity of the right ureter to the intended ablation target, a right ureteral stent for identification and protection of the ureter was placed prior to treatment. Previously our practice was to place stents in a separate operative suite prior to the MRI ablation procedure. More recently we have been able to place ureteral stents over a guidewire within the MRI interventional suite using a single-use flexible cystoscope. MRI is used for confirmation of wire and stent placement. Figure 4 shows the guidewire in the right renal collecting system and ureter.

Figure 4. Coronal turbo spin echo MRI demonstrating appropriate placement of guidewire into the right collecting system (arrows) prior to stent placement over wire.

Following adequate saline displacement of the rectum and ureteral stent placement, cryoablation was performed. A total of 3 cryoprobes were utilized. Continuous MRI was performed throughout the freezing process to monitor the iceball perimeter to ensure comprehensive coverage of the recurrent prostate cancer. Active thawing was employed following each of the 3 freeze-thaw cycles.1 Figure 5 shows real-time axial and sagittal MRIs obtained during treatment. Following the procedure the ureteral stent was removed and the patient was dismissed home the same day.

Figure 5. A, Axial image obtained via continuous MRI during iceball (black arrow) formation; red arrow shows stent within ureter. B, Sagittal image showing maximal iceball (black arrow) size at the completion of the freeze cycle.

This case highlights the usefulness of interventional MRI in prostate cancer care. Beginning with identification of the suspicious lesion, in-bore guided biopsy for disease localization and finally MRI-guided treatment with multiplanar MRI imaging was critical at each step of the patient’s care. Postprostatectomy patients who have completed salvage radiation and have image-guided, biopsy-proven localized disease have limited local therapy options. Many who received hormone treatment during their salvage radiation therapy are averse to repeat androgen deprivation. These select patients may be candidates for salvage MRI cryoablation. This approach offers a potential strategy for effective local disease control and delaying systemic therapy in this patient population.

  1. Woodrum DA, Kawashima A, Karnes RJ, et al. Magnetic resonance imaging-guided cryoablation of recurrent prostate cancer after radical prostatectomy: initial single institution experience. Urology. 2013;82(4):870-875.
  2. Lomas DJ, Woodrum DA, McLaren RH, et al. Rectal wall saline displacement for improved margin during MRI-guided cryoablation of primary and recurrent prostate cancer. Abdom Radiol. 2020;45(4):1155-1161.