Premium
MRI endoscopy using intrinsically localized probes
Author(s) -
Sathyanarayana Shashank,
Bottomley Paul A.
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3077125
Subject(s) - magnetic resonance imaging , endoscope , nuclear magnetic resonance , electromagnetic coil , materials science , excitation , optics , image resolution , biomedical engineering , radiofrequency coil , adiabatic process , excited state , sensitivity (control systems) , perpendicular , physics , radiology , atomic physics , geometry , mathematics , medicine , quantum mechanics , thermodynamics , electronic engineering , engineering
Magnetic resonance imaging (MRI) is traditionally performed with fixed externally applied gradient magnetic fields and is hence intrinsically locked to the laboratory frame of reference (FoR). Here a method for high‐resolution MRI that employs active, catheter‐based, tiny internal probes that utilize the spatial properties of the probe itself for localization is proposed and demonstrated at 3 T. Because these properties are intrinsic to the probe, they move with it, transforming MRI from the laboratory FoR to the FoR of the device itself, analogous to an endoscope. The “MRI endoscope” can utilize loop coils and loopless antennas with modified sensitivity, in combination with adiabatic excitation by the device itself, to restrict the MRI sensitivity to a disk‐shaped plane a few mm thick. Excitation with the MRI endoscope limits the eddy currents induced in the sample to an excited volume whose size is orders of magnitude below that excited by a conventional body MRI coil. Heat testing shows maximum local temperature increases of < 1 ° C during MRI, within regulatory guidelines. The method is demonstrated in a kiwifruit, in intact porcine and rabbit aortas, and in an atherosclerotic human iliac artery specimen, with in‐plane resolution as small as 80 μ m and 1.5–5 mm slice thickness.