title: Endoluminal ultrasound applicator with an integrated  RF coil for high-resolution magnetic resonance  imaging-guided high-intensity contact ultrasound  thermotherapy.
abstract: 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, a miniature receive-only coil was integrated into an endoscopic ultrasound applicator to offer high-resolution MRI guidance of thermotherapy. A cylindrical plastic support with an incorporated single element flat transducer (9.45 MHz, water cooling tip) was made and equipped with a rectangular RF loop coil surrounding the active element. The integrated coil provided significantly higher sensitivity than a four-element extracorporeal phased array coil, and the standard deviation of the MR thermometry (SDT) improved up to a factor of 7 at 10 mm depth in tissue. High-resolution morphological images (T1w-TFE and IR-T1w-TSE with a voxel size of 0.25 x 0.25 x 3 mm3) and accurate thermometry data (the PRFS method with a voxel size of 0.5 x 0.5 x 5 mm3, 2.2 s/image, 0.3 degree C voxel-wise SDT) were acquired in an ex vivo esophagus sample, on a clinical 1.5T scanner. The endoscopic device was actively operated under automatic temperature control, demonstrating a high level of accuracy (1.7% standard deviation, 1.1% error of mean value), which indicates that this technology may be suitable for HICU therapy of endoluminal cancer.
authors.affiliation: Inserm, U556, Université de Lyon, Lyon, F-69003, France.
authors.forename: Mihaela
authors.initials: M
authors.lastname: Rata
authors.forename: Rares
authors.initials: R
authors.lastname: Salomir
authors.forename: Reiner
authors.initials: R
authors.lastname: Umathum
authors.forename: Jürgen
authors.initials: J
authors.lastname: Jenne
authors.forename: Cyril
authors.initials: C
authors.lastname: Lafon
authors.forename: François
authors.initials: F
authors.lastname: Cotton
authors.forename: Michael
authors.initials: M
authors.lastname: Bock
mesh_terms: D000818:Animals; D016477:Artifacts; D004067:Digestive System Neoplasms / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000628:therapy; D019160:Endosonography / Q000295:instrumentation*; D004947:Esophagus / Q000000981:diagnostic imaging / Q000473:pathology; D006361:Heating; D006979:Hyperthermia, Induced / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging; D012680:Sensitivity and Specificity; D013552:Swine; D013696:Temperature