Catheter-based and endoluminal ultrasound applicators for magnetic resonance image-guided thermal therapy of pancreatic cancer: Preliminary investigations

Abstract

Ultrasound devices are being investigated for endoluminal and intraductal access for targeted thermal ablation or hyperthermia of pancreas under MR guidance and temperature monitoring. Simulations using patient-specific 3D models were developed for applicator design and development of treatment delivery strategies. MR-compatible devices were constructed for endoluminal (3-5 MHz planar or lightly focused rectangular elements, 12-mm OD assembly, expandable balloon), transgastric interstitial and intraductal (6-8 MHz multi-sectored tubular elements, 2-mm catheter) deployment. Micro-coils were integrated for active MR tracking of position and alignment. The proof-of-concept devices were tested in phantoms, ex vivo tissues, cadaveric porcine models, and in vivo animal models under 3T MR temperature imaging (MRTI). Results indicate endoluminal devices could ablate 2-2.5 cm depth from gastric wall for tumors of the pancreatic head, and multi-sectored tubular intraductal and interstitial applicators could ablate 2.3-3.4 cm diameter targets with directional control. Intraductal applicators could produce effective hyperthermia (>40 C) extending 15 mm radial. Customized tracking sequences could be used to locate 3D position of the applicators. Endoluminal, interstitial, and intraductal ultrasound applicators show promise for ablation or hyperthermia of pancreatic tumors. MR guidance can be employed for positioning these devices with active tracking coils and real time temperature monitoring. (NIH-P01CA159992.)

Catheter-based ultrasound technology for image-guided thermal therapy: Current technology and applications

“…Ancillary studies related to diffusion-weighted imaging [80] and refinement of MR techniques for motion compensation have also resulted from similar work [76, 113, 114]. MR thermometry techniques have also been explored for monitoring endoscopic ablation of liver and pancreatic tumors [58, 65, 66]. MRTI-based feedback control has been demonstrated using schemes such as proportional integral [43, 74, 75, 77, 78] and self-tuning [78] and robust predictive [77] controllers.…”