Respiratory-gated MRgHIFU in upper abdomen using an MR-compatible in-bore digital camera.
OBJECTIVE
To demonstrate the technical feasibility and the potential interest of using a digital optical camera inside the MR magnet bore for monitoring the breathing cycle and subsequently gating the PRFS MR thermometry, MR-ARFI measurement, and MRgHIFU sonication in the upper abdomen.


METHODS
A digital camera was reengineered to remove its magnetic parts and was further equipped with a 7 m long USB cable. The system was electromagnetically shielded and operated inside the bore of a closed 3T clinical scanner. Suitable triggers were generated based on real-time motion analysis of the images produced by the camera (resolution 640 × 480 pixels, 30 fps). Respiratory-gated MR-ARFI prepared MRgHIFU ablation was performed in the kidney and liver of two sheep in vivo, under general anaesthesia and ventilator-driven forced breathing.


RESULTS
The optical device demonstrated very good MR compatibility. The current setup permitted the acquisition of motion artefact-free and high resolution MR 2D ARFI and multiplanar interleaved PRFS thermometry (average SNR 30 in liver and 56 in kidney). Microscopic histology indicated precise focal lesions with sharply delineated margins following the respiratory-gated HIFU sonications.


CONCLUSIONS
The proof-of-concept for respiratory motion management in MRgHIFU using an in-bore digital camera has been validated in vivo.
Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland ; Clinatec/LETI/CEA, 38054 Grenoble, France.
Vincent
0000-0002-6385-3233
V
Auboiroux
Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland.
Lorena
L
Petrusca
Department of Radiology, University Hospitals of Geneva, 1211 Geneva, Switzerland.
Magalie
M
Viallon
Radiology Department, Lyon-Sud Hospital, University Hospitals of Lyon, 69495 Pierre Bénite, France ; CREATIS, CNRS UMR5220, INSERM U1044, University of Lyon, INSA Lyon, 69621 Villeurbanne, France.
Arnaud
A
Muller
Department of Radiology, University Hospitals of Geneva, 1211 Geneva, Switzerland.
Sylvain
0000-0003-1539-8587
S
Terraz
Department of Radiology, University Hospitals of Geneva, 1211 Geneva, Switzerland.
Romain
R
Breguet
Department of Radiology, University Hospitals of Geneva, 1211 Geneva, Switzerland.
Xavier
0000-0003-2442-5866
X
Montet
Department of Radiology, University Hospitals of Geneva, 1211 Geneva, Switzerland.
Christoph D
CD
Becker
Faculty of Medicine, University of Geneva, 1211 Geneva, Switzerland ; Department of Radiology, University Hospitals of Geneva, 1211 Geneva, Switzerland.
Rares
R
Salomir
D000005:Abdomen / Q000473:pathology*; D000818:Animals; D005260:Female; D007668:Kidney / Q000473:pathology; D008099:Liver / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D012119:Respiration; D012756:Sheep; D062125:Thermometry / Q000379:methods; D014463:Ultrasonography / Q000379:methods*