Prototype miniature endoluminal MR imaging catheter.
OBJECTIVE
The feasibility of a miniature endoluminal magnetic resonance (MR) detection coil was investigated for imaging mural and perimural anatomy of small, tubular structures.


METHODS
To this end, remotely tunable, single-loop, multiturn, receive-only radio-frequency coils, housed in 6-9-F arterial sheaths, were built. A 1.9-T imager was used. Phantom excitation was accomplished with a 62-mm-diameter bird-cage quadrature coil, and ex vivo specimen excitation was accomplished with a single-turn, untuned wire loop. Phantom images obtained with use of a 9-F catheter coil showed a signal-to-noise improvement on the border of 20 dB compared with images obtained with the quadrature coil. An 8-F catheter coil was used to obtain high-resolution (100 microns in-plane pixel size, 500 microns section thickness) spin-echo images (repetition time = 2,400 msec, echo time = 53 msec) of the wall of a fresh ex vivo human popliteal artery.


RESULTS
Prospectively, these images were suggestive of the presence of diffuse intimal hyperplasia, medial calcification, and focal atherosclerotic plaque. These findings were confirmed histologically. Three-dimensional restacking of the axial images simplified examination of the normal layers and pathologic changes within the wall. The improved signal-to-noise characteristics of these miniature coils permit fast high-resolution imaging, allowing visualization of microscopic anatomic details.


CONCLUSIONS
With further development, this technology may be useful for studying atherosclerosis and for providing imaging guidance during endoluminal MR interventions.
Division of Cardiovascular and Interventional Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115.
K
K
Kandarpa
P
P
Jakab
S
S
Patz
F J
FJ
Schoen
F A
FA
Jolesz
D001158:Arteries / Q000473:pathology; D002404:Catheterization / Q000295:instrumentation*; D006801:Humans; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008904:Miniaturization; D008961:Models, Structural; D011446:Prospective Studies; D014652:Vascular Diseases / Q000175:diagnosis