Validation of a low-cost, carbon dioxide-based cryoablation system for percutaneous tumor ablation.

Breast cancer rates are rising in low- and middle-income countries (LMICs), yet there is a lack of accessible and cost-effective treatment. As a result, the cancer burden and death rates are highest in LMICs. In an effort to meet this need, our work presents the design and feasibility of a low-cost cryoablation system using widely-available carbon dioxide as the only consumable. This system uses an 8-gauge outer-diameter needle and Joule-Thomson expansion to percutaneously necrose tissue with cryoablation. Bench top experiments characterized temperature dynamics in ultrasound gel demonstrated that isotherms greater than 2 cm were formed. Further, this system was applied to mammary tumors in an in vivo rat model and necrosis was verified by histopathology. Finally, freezing capacity under a large heat load was assessed with an in vivo porcine study, where volumes of necrosis greater than 1.5 cm in diameter confirmed by histopathology were induced in a highly perfused liver after two 7-minute freeze cycles. These results demonstrate the feasibility of a carbon-dioxide based cryoablation system for improving solid tumor treatment options in resource-constrained environments.

MR-guided portal vein delivery and monitoring of magnetocapsules: assessment of physiologic effects on the liver.

PURPOSE: The authors previously developed magnetic resonance (MR)-trackable magnetocapsules (MCs) that can simultaneously immunoprotect human islet cells and noninvasively monitor portal delivery and engraftment in real time with MR imaging. This study was designed to assess the physiologic effects of the delivery of a clinical dose of MCs (140,000 capsules) into the portal vein (PV) in swine over a 1-month period. MATERIALS AND METHODS: MCs were formed by using clinical-grade alginate mixed with a clinically applicable dosage of ferumoxide. Percutaneous access into the PV was obtained by using a custom-built, MR-trackable needle, and 140,000 MCs were delivered under MR guidance in five swine. Portal pressures and liver function data were obtained over a 4-week period. RESULTS: A transient increase in portal pressure occurred immediately after MC delivery that returned to normal levels by 4 weeks after MC delivery. Liver function test results were normal during the entire period, and the appearance of the MCs on MR imaging did not change. CONCLUSIONS: A clinically applicable dose of 140,000 MCs has no adverse effects on portal pressures or liver function in this normal swine model during the first month after delivery.

Cardiac magnetic resonance imaging in small rodents using clinical 1.5 T and 3.0 T scanners.

Cardiac magnetic resonance (CMR) imaging can provide noninvasive, high resolution images of heart anatomy, viability, perfusion, and function. However, the adoption of clinical CMR imaging protocols for small rodents has been limited due to the small heart size and rapid heart rates. Therefore, most CMR studies in small rodents have been performed on non-clinical, high-field MR magnets. Because such high-field systems are not readily available at most institutions, the technical aspects that are needed to perform CMR on clinical 1.5 T and 3.0 T MR scanners are presented in this paper. Equipment requirements are presented, and a comprehensive description of the methods needed to complete a CMR exam including the animal preparation, imaging, and image analysis are discussed. In addition, the advanced applications of myocardial tagging and delayed-contrast-enhanced imaging are reviewed for the assessment of regional contractile function and myocardial viability, respectively.