Radiology: Preop MRI may trim prostate surgery nerve damage risk
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Robotic-assisted laparoscopic prostatectomy (RALP) offers a prostate cancer treatment option that can reduce the risks of incontinence and impotence compared with radical prostatectomy.
“However, surgeons performing RALP lack tactile (haptic) feedback, upon which they traditionally rely to determine the extent of resection,” wrote Timothy D. McClure, MD, of the department of radiology at the David Geffen School of Medicine at University of California Los Angeles, and colleagues. This can interfere with the surgeon’s ability to assess the involvement of neurovascular bundles. An aggressive surgical approach could unnecessarily damage the bundles and leave patients with loss of function, while an approach that is not aggressive enough may leave some cancer behind.
McClure and colleagues designed the current study to determine whether preoperative MRI data influenced the extent of surgical margins (nerve-sparing vs. non-nerve-sparing technique) in RALP.
The study population included 104 men who met the inclusion criteria and underwent MRI of the prostate with an endorectal coil prior to RALP between January 2004 and April 2008.
Two radiologists evaluated the MR images for the presence of cancer and also used available apparent diffusion coefficient maps, dynamic contrast-enhanced images and MR spectroscopic images to inform the degree of suspicion.
The surgeon completed an initial nerve-sparing or non-nerve-sparing resection plan blinded to the MR data and then re-evaluated and adjusted the plan after review of the MR images.
Preoperative prostate MRI data changed the decision to use a nerve-sparing technique during RALP in 27 percent of the patients. The surgical plan was changed to the nerve-sparing technique in 17 of these 28 patients and to a non-nerve-sparing technique in 11 patients. The decision to opt for nerve-sparing surgery did not compromise oncologic outcome.
“I think preoperative MRI will be useful for surgeons who are uncertain whether to spare or resect the nerves,” said Daniel J. A. Margolis, MD, assistant professor of radiology at the David Geffen School of Medicine at the University of California Los Angeles, in a statement. “Our surgeons feel that, compared with clinical information alone, MRI is worthwhile for all patients, because it identifies important information leading to a change in the surgical plan in almost a third of patients.”
However, Margolis cautioned that the study group represented a population of men with low to medium grade cancer and that the findings might not apply to all patients. “There is a learning curve for prostate MRI,” Margolis said. “What we and others have found is that one has to select patients where there is likely to be a benefit from the imaging.”
For the approach to become more commonplace, Margolis said that two things were needed: a better way to stratify which patients would benefit from preoperative MRI, and a more standardized means of acquiring and interpreting prostate MRI results.
“The former is something we are investigating now,” Margolis said. “The latter is something that a number of leading experts in prostate MRI are working toward. However, most centers already have this technology, so this may become widespread relatively soon.”