High-resolution intravascular MRI-guided perivascular ultrasound ablation

Xiaoyang Liu, Nicholas Ellens, Emery Williams, Everette C. Burdette, Parag Karmarkar, Clifford R. Weiss, Dara Kraitchman, Paul A. Bottomley

Research output: Contribution to journalArticle

Abstract

Purpose: To develop and test in animal studies ex vivo and in vivo, an intravascular (IV) MRI-guided high-intensity focused ultrasound (HIFU) ablation method for targeting perivascular pathology with minimal injury to the vessel wall. Methods: IV-MRI antennas were combined with 2- to 4-mm diameter water-cooled IV-ultrasound ablation catheters for IV-MRI on a 3T clinical MRI scanner. A software interface was developed for monitoring thermal dose with real-time MRI thermometry, and an MRI-guided ablation protocol developed by repeat testing on muscle and liver tissue ex vivo. MRI thermal dose was measured as cumulative equivalent minutes at 43°C (CEM43). The IV-MRI IV-HIFU protocol was then tested by targeting perivascular ablations from the inferior vena cava of 2 pigs in vivo. Thermal dose and lesions were compared by gross and histological examination. Results: Ex vivo experiments yielded a 6-min ablation protocol with the IV-ultrasound catheter coolant at 3-4°C, a 30 mL/min flow rate, and 7 W ablation power. In 8 experiments, 5- to 10-mm thick thermal lesions of area 0.5-2 cm2 were produced that spared 1- to 2-mm margins of tissue abutting the catheters. The radial depths, areas, and preserved margins of ablation lesions measured from gross histology were highly correlated (r ≥ 0.79) with those measured from the CEM43 = 340 necrosis threshold determined by MRI thermometry. The psoas muscle was successfully targeted in the 2 live pigs, with the resulting ablations controlled under IV-MRI guidance. Conclusion: IV-MRI-guided, IV-HIFU has potential as a precision treatment option that could preserve critical blood vessel wall during ablation of nonresectable perivascular tumors or other pathologies.

Original languageEnglish (US)
Pages (from-to)240-253
Number of pages14
JournalMagnetic resonance in medicine
Volume83
Issue number1
DOIs
StatePublished - Jan 1 2020

Keywords

  • MR-guided ultrasound ablation
  • high intensity focused ultrasound (HIFU)
  • intravascular MRI (IVMRI)
  • liver and pancreatic cancer
  • vessel involvement

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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