Transurethral light delivery for prostate photoacoustic imaging.
Photoacoustic imaging has broad clinical potential to enhance prostate cancer detection and treatment, yet it is challenged by the lack of minimally invasive, deeply penetrating light delivery methods that provide sufficient visualization of targets (e.g., tumors, contrast agents, brachytherapy seeds). We constructed a side-firing fiber prototype for transurethral photoacoustic imaging of prostates with a dual-array (linear and curvilinear) transrectal ultrasound probe. A method to calculate the surface area and, thereby, estimate the laser fluence at this fiber tip was derived, validated, applied to various design parameters, and used as an input to three-dimensional Monte Carlo simulations. Brachytherapy seeds implanted in phantom, ex vivo, and in vivo canine prostates at radial distances of 5 to 30 mm from the urethra were imaged with the fiber prototype transmitting 1064 nm wavelength light with 2 to 8 mJ pulse energy. Prebeamformed images were displayed in real time at a rate of 3 to 5 frames per second to guide fiber placement and beamformed offline. A conventional delay-and-sum beamformer provided decreasing seed contrast (23 to 9 dB) with increasing urethra-to-target distance, while the short-lag spatial coherence beamformer provided improved and relatively constant seed contrast (28 to 32 dB) regardless of distance, thus improving multitarget visualization in single and combined curvilinear images acquired with the fiber rotating and the probe fixed. The proposed light delivery and beamforming methods promise to improve key prostate cancer detection and treatment strategies.
Johns Hopkins University, CISST Engineering Research Center, Baltimore, Maryland 21218, United StatesbJohns Hopkins University School of Medicine, Department of Radiology, Baltimore, Maryland 21205, United States.
Muyinatu A
MA
Lediju Bell
Johns Hopkins University, Department of Electrical and Computer Engineering, Baltimore, Maryland 21218, United States.
Xiaoyu
X
Guo
Johns Hopkins University School of Medicine, Department of Radiation Oncology and Molecular Sciences, Baltimore, Maryland 21205, United States.
Danny Y
DY
Song
Johns Hopkins University, CISST Engineering Research Center, Baltimore, Maryland 21218, United StatesbJohns Hopkins University School of Medicine, Department of Radiology, Baltimore, Maryland 21205, United StatescJohns Hopkins University, Department of El.
Emad M
EM
Boctor
D000818:Animals; D001918:Brachytherapy / Q000295:instrumentation; D004285:Dogs; D019160:Endosonography / Q000379:methods; D005336:Fiber Optic Technology / Q000295:instrumentation; D008297:Male; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D061088:Photoacoustic Techniques / Q000295:instrumentation; D011467:Prostate / Q000000981:diagnostic imaging*; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging*; D014463:Ultrasonography / Q000295:instrumentation / Q000379:methods*