Intravascular Optical-Resolution Photoacoustic Tomography with a 1.1 mm Diameter Catheter

Abstract

Photoacoustic imaging is an emerging technology that can provide anatomic, functional, and molecular information about biological tissue. Intravascular spectroscopic and molecular photoacoustic imaging can potentially improve the identification of atherosclerotic plaque composition, the detection of inflammation, and ultimately the risk stratification of atherosclerosis. In this study, a first-of-its-kind intravascular optical-resolution photoacoustic tomography (OR-PAT) system with a 1.1 mm diameter catheter is developed, offering optical-diffraction limited transverse resolution as fine as 19.6 μm, ∼10-fold finer than that of conventional intravascular photoacoustic and ultrasonic imaging. To offer complementary imaging information and depth, the system also acquires co-registered intravascular ultrasound images in parallel. Imaging of an iliac stent and a lipid phantom shows that the high resolution and contrast of OR-PAT can enable improved stent implantation guidance and lipid identification. In the future, these capabilities may ultimately improve the diagnosis and interventional treatment of vulnerable atherosclerotic plaques, which are prone to cause thrombotic complications such as myocardial infarction and stroke.

Label-free optical-resolution photoacoustic endomicroscopy in vivo

“…As shown in the in vivo and ex vivo image demonstrations, the major benefit of the OR-PAEM over existing IVM techniques [44][45][46][47][48][49][50][51][52][53][54][55][56] lies in its label-free angiographic imaging capability, which provides critical image in experimental biology and clinical medicine. Although other groups [57,58] developed endoscopic devices with optical focusing and achieved an even smaller probe diameter (i.e., ~1.1 mm in the case of ref. 57), their probes, currently not fully encapsulated, cannot be utilized for in vivo IVM.…”

“…Although other groups [57,58] developed endoscopic devices with optical focusing and achieved an even smaller probe diameter (i.e., ~1.1 mm in the case of ref. 57), their probes, currently not fully encapsulated, cannot be utilized for in vivo IVM. We emphasize that full probe encapsulation is the most critical requirement for minimally-invasive clinical IVM imaging.…”

“…To demonstrate the new imaging probe's in vivo imaging ability, we imaged the descending colons of two rats and acquired the first in vivo OR-PAEM image. The spatial resolution is the highest yet reported for optical-resolution endoscopic PA images [57,58].…”

“…Very recently, two research groups reported such endoscopic devices with optical focusing and demonstrated PA images with transverse resolutions of 19.6 µm and 15.7 µm, respectively [57,58]. However, their imaging probes were not fully encapsulated, and thus they could demonstrate the systems by imaging only phantoms, such as a metallic stent.…”

Polymer Optical Fibre Sensors for Endoscopic Opto-Acoustic Imaging

“…Jenson et al established the need for a target endoscopic probe diameter of less than 1mm for clinical imaging, which has not yet been achieved to the best of our knowledge [2]. Recent advances include a 2.5mm diameter dual-mode endoscope by Yang et al in 2012 [3], followed by a 1.1mm probe by Bai et al in 2014 [4]. The latter submission discusses the relationship between size and sensitivity of piezo-electric transducers, an important issue given the target diameter and the widespread promulgation of piezo-electric transducers as detectors.…”