UCSD. US: More accurate diagnoses could mean less invasive interventions, more surveillance
In 2014, prostate cancer was the leading cause of newly
diagnosed cancers in men and the second leading cause of cancer death in
men. Writing in the January 6, 2015 issue of the journal Prostate Cancer and Prostatic Disease,
a team of scientists and physicians from the University of California,
San Diego School of Medicine, with counterparts at University of
California, Los Angeles, describe a novel imaging technique that
measurably improves upon current prostate imaging – and may have
significant implications for how patients with prostate cancer are
ultimately treated.
“This new approach is a more reliable imaging technique for
localizing tumors. It provides a better target for biopsies, especially
for smaller tumors,” said Rebecca Rakow-Penner, MD, PhD, a research
resident in the Department of Radiology and the study’s first author.
The technique is also valuable in surgical planning and image
staging, said David S. Karow, MD, PhD, assistant professor of radiology
at UC San Diego and the study’s corresponding author. “Doctors at UC San
Diego and UCLA now have a non-invasive imaging method to more
accurately assess the local extent of the tumor and possibly predict the
grade of the tumor, which can help them more precisely and effectively
determine appropriate treatment.”
The current standard of care for detecting and diagnosing prostate
cancer is contrast enhanced magnetic resonance imaging (MRI), which
involves intravenously injecting patients with a contrast agent to
highlight blood flow. Greater blood flow is often a requirement of
growing cancer cells. When compared to surrounding healthy tissues, it’s
hoped that contrast enhanced MRIs will reveal the shape and nature of
any tumors present.
But many tumors do not significantly differ from surrounding healthy
tissues with contrast enhanced MRI and so evade easy detection. An
imaging technique called diffusion MRI measures the diffusion of water
and has been a standard imaging technique in the brain and an emerging
technique in the prostate. Cancer tissues are denser than healthy
tissues and typically limit the amount and mobility of water within
them. But diffusion MRI suffers from magnetic field artifacts that can
distort the actual location of tumors by as much as 1.2 centimeters or
roughly half an inch – a significant distance when surgeons are
attempting, for example, to assess whether a tumor extends beyond the
prostate and into adjacent nerve bundles.
The new approach described in today’s published paper is called
restriction spectrum imaging-MRI or RSI-MRI. It corrects for magnetic
field distortions and focuses upon water diffusion within tumor cells.
By doing both, the ability of imaging to accurately plot a tumor’s
location is increased and there is a more refined sense of the tumor’s
extent, said Nathan White, PhD, assistant project scientist at UC San
Diego, study co-author and co-inventor of the RSI-MRI technique.
In a related paper to be published in the journal Frontiers in Oncology,
the same team of researchers reported that RSI-MRI appears to predict
tumor grade. Higher grade tumors correlate with higher restricted water
volume in the cancer cells’ large nuclei.
“Prostate cancer can often be an indolent disease, where a patient
may only require surveillance rather than aggressive surgery,” noted
co-author Christopher J. Kane, MD, professor of urology at UC San Diego.
“If by imaging we could predict the tumor grade,” added Robert
Reiter, MD, professor of urology at UCLA, “we may be able to spare some
patients from prostate resection and monitor their cancer with imaging.”
Co-authors include senior author Anders M. Dale, Hyung W. Choi,
Joshua M. Kuperman, Natalie M. Schenker-Ahmed, Hauke Bartsch, Robert F.
Mattrey and William G. Bradley, Department of Radiology, UCSD; J.
Kellogg Parsons and Michael A. Liss, Department of Urology, UCSD; Ahmed
Shabaik, Department of Pathology, UCSD; Jiaoti Huang, Department of
Pathology, UCLA; Daniel J. Margolis and Steven S. Raman, Department of
Radiology, UCLA; Leonard S. Marks, Department of Urology, UCLA.
Funding for this research was provided, in part, by the National
Institute of Biomedical Imaging and Bioengineering of the National
Institutes of Health, the Department of Defense, Prostate Cancer
Research Program, the American Cancer Society and the UC San Diego
Clinician Scientist Program.