Prostate cancer may face new foe in photoacoustic/ultrasound imaging

Researchers at Japan’s National Defense Medical College have developed an ultrasound-equipped photoacoustic imaging (PAI) system that shows potential for imaging the angiogenesis, or formation of troublesome new blood vessels, in prostate cancer.

Akio Horiguchi, MD, and colleagues from the college, along with a research and development scientist from Fujifilm, describe their pilot study in Urology.

The team’s novel PAI system uses a transrectal ultrasound-type probe.

The researchers included in their study three patients who underwent PAI just before prostate biopsy and subsequently underwent radical prostatectomy.

They retrospectively reviewed the PAI appearance, focusing on four representative areas: one with high PAI signal intensity, one with low PAI signal intensity, one peripheral to the index tumor and one inside the index tumor.

Horiguchi and co-authors analyzed the correlation of PAI intensity with three microvascular parameters—microvascular density, total vascular area and total vascular length—as assessed by immunostaining in resected specimens.

“In all cases the PAI intensity, total vascular area and total vascular length in areas with high-intensity PAI signals were significantly higher than those in areas with low-intensity PAI signals, suggesting that PAI appearance describes the distribution of microvasculature in prostatic tissue correctly,” the authors write.

Further, they report, all index tumors showed a ring-like PAI appearance consisting of a peripheral area of high signal intensity completely or partially surrounding an area with low signal intensity.

Additionally, the PAI intensity, total vascular area and total vascular length in the periphery of the index tumors were significantly higher than those inside of the index tumors.

“We herein showed experimental and preliminary results of PAI in three cases of prostate cancer,” Horiguchi et al. conclude. “The intensity of PAI signals might reflect the microvascularity in normal prostatic tissues and index tumors. A ring-like PAI appearance could be specific for prostate cancer, and PAI could be a novel modality for imaging prostate cancer angiogenesis.”