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Sherif G. Nour¹, ², Jamal J. Derakhshan, Simi Paul¹, Jens O. Heidenreich¹, Nathan Cross², Fadi W. Abdul-Karim¹, Jeong J. Park, Jeffrey L. Sunshine¹, Jeffrey L. Duerk¹

¹University Hospitals Case Medical center / Case Western Reserve University, Cleveland, Ohio, USA; ²School of Medicine / Case Western Reserve University, Cleveland, Ohio, USA

Reducing tongue base volume has been shown to improve clinical outcomes in patients with obstructive sleep apnea (OSA). A technique for percutaneous laser ablation of the tongue base entirely guided and monitored under MRI is described and tested on porcine models. The ability to safely create large, therapeutic-type ablations within the tongue base utilizing this technique and the effect of this single-session treatment on tongue base shrinkage were specifically evaluated. Both safety and efficacy have been demonstrated. These results represent the first use of IMRI technology to achieve laser-induced glossectomy and constitute promising basis for future treatment of OSA patients.

Alexandru Cernicanu¹, Matthieu Lepetit-Coiffe¹, Magalie Viallon¹, Sylvain Terraz¹, Christoph D. Becker¹

¹Geneva University Hospital, Geneva, Switzerland

With a closed-bore 1.5T MR system, clinical treatment of metastatic liver tumours (under 2.5 cm in diameter) using RF ablation technique was studied regarding targeting and real-time MR temperature monitoring; Based on a fully-balanced SSFP interleaved radial acquisition, targeting of the deep-situated tumour was achieved in about 22±10min; The RF device was made MR compatible in order to perform MR thermometry with a respiratory-triggered rapid gradient echo-echo planar imaging acquisition; MR temperature accuracy of 1.6±0.5 C was obtained in a non-heated region. Long axis diameter of RF lesion was 3.4±0.7cm overlapping the tumour in 14 of 15 nodules (confirmed both by 2-days-later-CT and 1-month-later-MR clinical images).

Axel Krafft¹, Jürgen Jenne¹, Jaane Rauschenberg¹, Wolfhard Semmler¹, R Jason Stafford², Michael Bock¹

¹Deutsches Krebsforschungszentrum (dkfz), Heidelberg, Germany; ²The University of Texas, MD Anderson Cancer Center, Houston, USA

High intensity focused ultrasound (HIFU) is a non-invasive treatment modality which is often monitored by MR temperature measurements to assess and control thermal target tissue ablation. In this work a fixed-focus HIFU transducer was for the first time combined with a fully MR-compatible robotic assistance system originally designed for percutaneous MR-guided needle interventions. This combined system is tested for its suitability for MR-guided focus ultrasound applications in a phantom and an in vivo experiment. The combined system potentially offers greater flexibility than existing HIFU setups and can achieve a high geometric precision in very short positioning times.

Max Köhler¹, Charles Mougenot², ³, Bruno Quesson³, Julia Enholm¹, Brigitte Lebail⁴, Christophe Laurent⁵, Chrit Moonen³, Gösta Ehnholm¹

¹Philips Medical Systems, Vantaa, Finland; ²Philips Medical Systems, France; ³Laboratory for Molecular and Functional Imaging, Bordeaux, France; ⁴Pellegrin Hospital, Bordeaux, France; ⁵Saint André Hospital, Bordeaux, France

A volumetric sonication method in conjunction with a simultaneous rapid volumetric thermal monitoring is introduced as a safe, fast and accurate alternative to current point-by-point sonication methods. This study on in-vivo pig thighs demonstrates an improved ablation efficiency and homogeneity with increased sonication volumes. Apparent lesion volume dimensions as seen from the thermal dose maps were in good agreement with corresponding non-perfused contrast enhanced dimensions.

Annemarie Caroline Schmitz¹, ², Maurice A. A. J. van den Bosch², Viola Rieke², Fred M. Dirbas², Kim Butts Pauly², Willem P.T.M. Mali¹, Bruce L. Daniel²

¹University Medical Center Utrecht, Utrecht, Netherlands; ²Stanford University Medical Center, Stanford, USA

The purpose of this experimental study is to compare the accuracy of MRI-guided focused ultrasound ablation(MRI-gFUS) versus MRI-guided needle-wire placement(MRI-gNW) for the localization of non-palpable breast tumors. Sixteen turkey breasts were used. An artificial tumor was created. MRI-gFUS localization(n=8) was performed with the ExAlblate 2000 system(Insightec). No case of positive margins was found in the FUS-group(0%) and 2 cases in the NW-group(25%)(P=0.5). The mean minimum tumor-free margin±SD in the FUS-group was significantly larger(4.7±2.9mm), than the NW-group(0.9±1.4mm)(P=0.004).The results of this experimental study indicate that MRIg-FUS is as accurate as MRIg-NW for pre-operative localization of non-palpable breast tumor.

Mihaela Rata¹, ², Rares Salomir¹, Reiner Umathum³, Jurgen Jenne³, François Cotton, ²⁴, Cyril Lafon¹, Michael Bock³

¹INSERM, U 556, Lyon, France; ²UCBL 1, Lyon, France; ³DKFZ, Heidelberg, Germany; ⁴CHU Lyon Sud, Lyon, France

High intensity contact ultrasound (HICU) under MRI guidance may provide minimally invasive treatment of endocavitary digestive tumors in the esophagus, colon or rectum. In this study, miniature receive-only coils were integrated into an endoscopic ultrasound applicator to offer high resolution MRI guidance of thermotherapy. The integrated coils provided significantly higher sensitivity than a 4-element extracorporeal phased array coil and the standard deviation of the MR thermometry (SDT) improved by to a factor of 7 at 10 mm depth in tissue. Half millimeter resolution became feasible for fast MR thermometry while providing an excellent SDT (0.3 C).  The endoscopic device was actively operated under automatic temperature control, demonstrating very accurate performance.

Michael Peller¹, Alenka Schwerdt², Martin Hossann³, Herbert M. Reinl⁴, Tungte Wang³, ⁵, Lars H. Lindner³, ⁶, Maximilian Reiser

¹University Hospital of Munich, Munich, Germany; ²Ludwig-Maximilians University, Munich, Germany; ³University Hospital of Munich, Germany; ⁴Department of Clinical Radiology, Germany; ⁵GSF-National Research Center for Environment, Neuherberg, Germany; ⁶ GSF-National Research Center for Environment, Neuherberg, Germany

Purpose of this study was to investigate the dynamics of mild temperature induced contrast agent release from phosphatidylglyceroglycerol containing thermosensitive liposomes with encapsulated Gd-DTPA-BMA (Gd-TSL) in the presence of tumor perfusion, using a clinical experimental setting. Tumor bearing mice were investigated at 1.5T after intravenous injection. The temperature induced release of contrast agent at 42 C causes a fast and strong increase of T1-weigthed signal. Intraindividual comparison of heated and non-heated tumors showed a significant higher contrast agent release in heated tumors. This demonstrates the potential of Gd-TSL for monitoring moderate regional hyperthermia in tumor treatment concepts in a clinical MRI-setting.  

Omer Eker¹, Bruno Quesson¹, Nora Frulio¹, Colette Deminiere², Chrit Moonen¹, Franck Couillaud¹, Nicolas Grenier¹

¹Laboratory IMF, Bordeaux, France; ²CHU Pellegrin, Bordeaux, France

Gene therapy using a cellular vector requires efficient targeting and control of the activation of the transgene of interest. Genetically modified C6 cells expressing Luciferase under a heat sensitive promoter have been injected in the renal artery and their intrarenal distribution visualized by Bioluminescence imaging. Two days after injection, kidneys were focally heated non invasively with HIFU under MRI thermometry automatic control, with different heating conditions. Presence of these cells in the kidney were successfully detected by Bioluminescence imaging and the zones emitting light corresponded to the heated region, indicative of successful in vivo targeting and control of transgene activation.

Lisa Hsu Treat¹, ², Yongzhi Zhang¹, Nathan McDannold¹, Kullervo Hynynen¹, ³

¹Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts, USA; ²Harvard-MIT Health Sciences and Technology, Cambridge, Massachusetts, USA; ³Sunnybrook Health Sciences Centre, Toronto, Canada

We investigated the impact of MRI-guided focused ultrasound-enhanced delivery of doxorubicin to brain on survival in rats with 9L gliosarcoma. In this study, we have shown that targeted drug delivery by MRI-guided focused ultrasound significantly improves survival time in rats with aggressive glioma, compared to chemotherapy alone (0.02< p<0.05). Such demonstrated efficacy in an in vivo tumor model represents a large step forward in the development of this technique toward treating patients with disorders of the central nervous system.

April M. Chow¹, ², Chi-tat Chiu¹, Ke Xia Cai¹, Ed X. Wu¹

¹The University of Hong Kong, Pokfulam, Hong Kong

Ultrasound-targeted Microbubble Destruction (UTMD) has been used to deliver genes or drugs to specific tissues utilizing microbubbles cavitation and sonoporation effect through guidance of ultrasound imaging. However, ultrasound imaging cannot visualize soft tissues adequately and non-site-specific therapeutic effect may result from the imaging ultrasound irradiation. MRI would be the most effective imaging modality to guide UTMD for genes or drugs delivery due to its better soft tissue delineation without interaction with microbubbles. In this study, we demonstrate that MRI can detect microbubble cavitation and MRI monitoring of UTMD is feasible.