ULTRAsoNle IMAGING 29,167-181 (2007) Investigation of Micro-Ultrasound for Microvessel Imaging in a Model of Chronic Total Occlusion

The aim of the current study is to investigate the ability of micro-ultrasound (!-IUS) to identify microvasculature in CI'Os in vivo. Results are compared with MRI studies. C'I'Os were developed in nine porcine superficial femoral arteries (SFA) by percutaneous insertion of a dissolvable polymer plug. This model is characterized by acute thrombosis that later organizes into a fibrotic Cf'O containing abun-dant microchannels. 3D!-IUS images with Power Doppler (PD) overlays from the arteries were acquired at two timepoints: one and eight weeks after placement ofthe polymerplug. Phase contrast MRI and con-trast enhanced MRI was also performed. Imaging was performed transcutaneously. Microvessels were identified in vivo in six of eight C'I'Os using!-IUS, and in three ofseven CI'O vessels with MRI, compared with five of seven seen histologically. PW Doppler profiles showed pulsatile blood velocities of-2 cm/s. Intraluminal microvessels within CTOs can be consistently identified by 3D!-IUS. This technique ap-pears to be more sensitive than MRI.!-IUS may playa role in guiding C'I'O interventions. Key words: Chronic total occlusion; contrast enhanced MRI; coronary artery disease; Doppler ultra-sound; intravascular ultrasound, micro-ultrasound; microvessels