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Monday, December 02, 2013

Multiparametric MR Aids Earlier Detection of Prostate Cancer Recurrence

Varaha Tammisetti, M.D.

Multiparametric MR (mp-MR) can enable earlier detection of cancer recurrence and improve treatment planning in patients who experience an increase in prostate specific antigen (PSA) after undergoing treatment for prostate cancer, according to the author of an education exhibit presented Sunday.

Prostate cancer is treated most often with surgery and radiation therapy as first-line therapy. In many cases, patients experience elevated levels of PSA after treatment, but the elevated levels are not always indicative of local recurrence or extensive metastatic disease, said Varaha Tammisetti, M.D., of the University of Texas Health Science Center at Houston.

"Elevated PSA levels don't tell if there is a recurrence, and if there is recurrence, they don't tell you if the cancer has spread outside of the prostate," Dr. Tammisetti said. "Some patients get blind therapy without evidence of a recurrence."

The education exhibit demonstrates how mp-MR combines different MR imaging techniques to provide more accurate information about both anatomy and function in patients with PSA relapse.

"Conventional imaging such as bone scans and CT are helpful only when disease is significantly advanced or metastatic, at which time treatment options are palliative rather than curative," said Dr. Tammisetti. "With MRI we combine the advantage of the high-contrast resolution of MR with functional parameters like information on how tightly cells are packed, how blood flows in tissue and the chemical makeup of tissue. Therefore, with MRI we can detect recurrence at an earlier point than other modalities, speeding the onset of appropriate treatments."

The education exhibit covers patterns of prostate cancer recurrence on MR imaging, from local recurrence to distant metastases—most commonly in lymph nodes or bone—and combined local and distant recurrence. Also discussed was the role of mp-MR in the imaging strategies for different types of recurrences. For instance, dynamic contrast-enhanced (DCE) MR is effective in helping detect small-sized prostate cancer recurrence after radical prostactectomy, while a combination of DCE-MR and diffusion-weighted imaging (DWI) is highly efficient after external-beam radiation therapy. Some research points to a complementary role for the two approaches. "The key challenge with a PSA rise is distinguishing a local recurrence from metastatic disease," Dr. Tammisetti said.

In addition to aiding in the identification of local recurrence, prostate mp-MR provides more accurate information on the extent of the tumor, which is useful when choosing a second-line treatment such as cryoablation or androgen deprivation therapy. After radiation therapy, mp-MR helps with accurate tumor localization, important in image-guided minimally invasive therapy or image-guided biopsy. It is also effective for guiding biopsies.

Dr. Tammisetti suggested that the most optimal use of mp-MR in patients with PSA relapse would be as a complement to PET with choline or other newer agents to measure specific changes in metabolic activity associated with cancer. While literature on choline PET is still evolving, it has already shown effectiveness at helping identify systemic disease, but it may not have as much spatial resolution as MR to detect smaller-sized local recurrence.

"In the future, we may see multiparametric MR integrated into the workup of recurrent cancer along with choline PET and other newer PET agents," Dr. Tammisetti said.

Other exhibit authors are Venkateswar Rao Surabhi, M.D., Eduardo J. Matta, M.D., Larry A. Kramer, M.D., and Robert J. Amato. View the exhibit, LL-URE-SU6A, through Friday in the Lakeside Learning Center. Virtual Meeting registrants may log in to view the exhibit from outside McCormick Place.

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© 2013 RSNA. The RSNA 2013 Daily Bulletin is the official publication of the 99th Scientific Assembly and Annual Meeting of the Radiological Society of North America. Published Sunday, December 1 - Thursday, December 5.

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