IMAGING OF VASCULAR MALFORMATIONS WITH A HIGH-INTENSITY FOCUSED ULTRASOUND PROBE FOR TREATMENT PLANNING.

OBJECTIVE We aimed to investigate whether a current commercially available High-Intensity Focused Ultrasound (HIFU) probe can adequately image targeted vascular malformations in anticipation of HIFU treatment planning and delivery. METHODS We enrolled 10 consecutive patients scheduled to undergo treatment of their symptomatic peripheral vascular malformations (VM) confirmed on routine preoperative contrast enhanced magnetic resonance imaging (MRI) and soft tissue duplex ultrasound (DUS). Lesions were situated no more than 6 cm from the skin. Following induction of general anesthesia and prior to surgical intervention, we prepared and positioned the Sonablate HIFU probe (SonaCare Medical, LLC, Charlotte, NC) so as to obtain multiple B-mode images of the targeted VM in transverse and longitudinal dimensions. We then rated the quality of the images and the feasibility of the imaging process itself based on a previously devised questionnaire aimed at evaluating the adequacy of the images for potential HIFU treatment planning and delivery. Patients, otherwise, underwent surgical intervention and clinical follow-up for their malformation per standard protocol. RESULTS Study consisted of 10 participants aged 21 to 67 years (M=36.5, SD=16.5). Six patients (60%) identified as female. VMs imaged consisted of 8 (80%) venous, 1 (10%) lymphatic, and 1 (10%) combined lymphatic-venous malformation; and were in the extremities only (50%), trunk only (20%), trunk and extremities (20%), or neck and extremities (10%). Pain related to the VM was present in all patients (100%). In all patients, the boundary and location of the VM was able to be visualized via the HIFU probe despite diminished B-mode imaging resolution. The absence of Doppler functionality in the HIFU probe did not prevent the identification of VMs in any patients up to a depth of 6 cm. On the basis of the post-imaging survey, difficulty of preparing the study device for imaging was 1.1 (±0.3), and difficulty of use was 1.1 (±0.1), with 1 equal to "easy" and 5 equal to "difficult". Stability of acoustic coupling to the patient was 1.3 (±0.2), with a score of 1 representing "very stable". CONCLUSIONS We were able to ultrasonically identify and outline all targeted peripheral VMs with a commercially available HIFU probe in anticipation of treatment planning and delivery. Baseline MRI and soft tissue DUS remain essential tools for guiding probe placement and HIFU imaging.