Optoacoustic imaging of the prostate: development toward image-guided biopsy

Abstract

Abstract.Optoacoustic ͑OA͒ tomography has demonstrated utility in identifying blood-rich malignancies in breast tissue. We describe the development and characterization of a laser OA imaging system for the prostate ͑LOIS-P͒. The system consists of a fiber-coupled Q-switched laser operating at 757 nm, a commercial 128-channel ultrasonic probe, a digital signal processor, and software that uses the filtered radial back-projection algorithm for image reconstruction. The system is used to reconstruct OA images of a blood-rich lesion induced in vivo in a canine prostate. OA images obtained in vivo are compared to images acquired using ultrasound, the current gold standard for guiding biopsy of the prostate. Although key structural features such as the urethra could be identified with both imaging techniques, a bloody lesion representing a highly vascularized tumor could only be clearly identified in OA images. The advantages and limitations of both forward and backward illumination modes are also evaluated by collecting OA images of phantoms simulating blood vessels within tissue. System resolution is estimated to be 0.2 mm in the radial direction of the acoustic array. The minimum detectable pressure signal is 1.83 Pa. Our results encourage further development toward a dual-modality OA/ultrasonic system for prostate imaging and image-guided biopsy.

Photoacoustic Imaging in Oncology: Translational Preclinical and Early Clinical Experience

“…Several research groups have conducted photoacoustic imaging of prostate cancer in vivo using animal models (76)(77)(78)(79)(80) ) was performed in 0.2-mm increments on three metastatic and nine benign lymph nodes excised from eight melanoma patients undergoing lymphadenectomy by using a 21-MHz linear US array (Vevo LAZR, Fujifilm VisualSonics) at 20-minute scans for each node (98). Results indicate that metastasized melanin was differentially detected from blood in resected human lymph nodes.…”

Photoacoustic imaging of prostate cancer

“…55 The human prostate is located beyond this penetration limit from the skin surface 56 ; therefore, human prostate PAI with an external light source is currently unfeasible. Fortunately, the feasibility of prostate PAI using endoscopic light delivery has been well demonstrated through phantom studies, 57,58 simulation studies, 55,59,60 and animal studies. 57,58 One of the major challenges of human prostate PAI is the delivery of the light source.…”

“…Fortunately, the feasibility of prostate PAI using endoscopic light delivery has been well demonstrated through phantom studies, 57,58 simulation studies, 55,59,60 and animal studies. 57,58 One of the major challenges of human prostate PAI is the delivery of the light source. Ideally, the light source must be capable of illuminating the whole prostate while minimizing invasiveness.…”

A 25-mm diameter probe for photoacoustic and ultrasonic endoscopy

“…Ultrasound image contrast relies on bulk mechanical properties of tissue, providing limited functional information, whereas PAT's spectroscopic imaging capability provides a wealth of physiological or functional information, including hemoglobin concentration, oxygen saturation of hemoglobin [8][9][10][11][12], velocity of blood flow [13,14], temperature [15], pH [16], etc. Due to these benefits, PAE [1,2] and other minimally invasive imaging techniques based on PAT [6,17,18] have been intensely developed for applications in such clinical areas as the cardiovascular [18][19][20][21][22][23][24][25], gastrointestinal [2,26,27], and urogenital [28][29][30][31] systems. These techniques are expected to provide a useful complement to other endoscopic modalities, such as endoscopic ultrasound (EUS) [32,33], endoscopic optical coherence tomography (OCT) [34][35][36][37][38][39][40], confocal endoscopy [41,42], and endoscopic polarized scanning spectroscopy [43,44].…”