Scientific Session 03 — SS03: Genitourinary Imaging - Prostate Cancer/RenalMonday, May 6, 2019
3029. First In-vivo Trial of Subharmonic Contrast-Enhanced Imaging for Detection of Prostate Cancer
Halpern E1*, Trabulsi E1, Machado P1, Wallace K2, Forsberg F1 1. Thomas Jefferson University, Philadelphia, PA; 2. General Electric, Niskayuna, NY
Address correspondence to E. Halpern (email@example.com)
Objective: We have previously demonstrated the utility of contrast enhanced harmonic imaging (HI) for detection of prostate cancer (PCa). Subharmonic imaging (SHI) is a new technique for imaging of microbubble ultrasound contrast agents with improved suppression of background signal originating from unenhanced tissue, resulting in up to a 10-fold increase in contrast-to-background signal ratio relative to conventional HI. We conducted a pilot study to evaluate contrast-enhanced SHI of the prostate for detection of PCa.
Materials and Methods: Fifty-five patients referred for prostate biopsy were included in this study supported by a grant from the NIH: R21 CA202214. The study population included 31 patients with a prior negative MRI or negative MRI-guided biopsy of the prostate. Each patient was imaged with a transrectal IC5-9D ultrasound transducer on modified Logiq E9 system (GE Healthcare; Milwaukee, WI) that was altered to perform SHI (transmit/receive: 7.0/3.5 MHz). Ultrasound contrast agent was infused intravenously over 10 minutes with 3 mL of Definity™ (Perflutren Lipid Microsphere, Lantheus Medical Imaging; N. Billerica, MA) diluted in 50 mL of saline. Images were obtained with conventional grayscale, color, and power Doppler, conventional contrast HI, SHI, and flash replenishment in combination with SHI (MIP-SHI). Doppler flow and contrast enhancement were rated on a 5-point subjective scale for each sextant of the prostate. Prostate biopsy was performed with up to 6 targeted cores by use of contrast-enhanced imaging, followed by a 12-part systematic biopsy.
Results: Contrast enhancement was clearly observed with both HI and SHI techniques in all participants. SHI provided improved contrast signal and tissue suppression relative to conventional HI. Microvascular architecture and increased vascularity were best delineated with MIP-SHI. Each contrast enhanced technique demonstrated statistically significant predictive value for localization of PCa (p<0.03). With multivariate regression, SHI demonstrated significant predictive value beyond the predictive value of unenhanced imaging (P<0.03). PCa was identified in 24 of 55 patients, including 9 of 31 patients with a prior negative MRI or negative MRI-guided biopsy.
Conclusion: This first in vivo application of contrast-enhanced SHI in the prostate demonstrated enhancement in all patients, with focal areas of contrast enhancement predictive of PCa in targeted biopsy specimens. Detection of PCa included 9 patients whose PCa was not identified by MRI. SHI is an independent predictor of PCa, beyond conventional grayscale and Doppler imaging. SHI may be useful in detection of PCa not found by multiparametric MRI.