Optimizing T2-weighted magnetic resonance sequences for surface coil microimaging of the eye with regard to lid, eyeball and head moving artifacts.
OBJECTIVE
To acquire high-resolution magnetic resonance (MR) images, we developed a new blinking artifact reduced pulse (BARP) sequence with a surface coil specialized for microscopic imaging (47 mm in diameter).


METHODS
To reduce eye movement, we ascertained that the subjects' eyes were kept open and fixated to the target in the 1.5-T MR gantry. To reduce motion artifacts from blinking, we inserted rest periods for blinking (1.5 s within every 5 s) during MR scanning (T2-weighted fast spin echo; repetition time, 5 s; echo time, 100 ms; echo train, 11; matrix, 256 x 128; field of view, 5 cm; 1-mm thickness x 30 slices). Three scans (100 s x 3) were performed for each normal subject, and they were added together after automatic adjustment for location to reduce quality loss caused by head motion.


RESULTS
T2-weighted MR images were acquired with a high resolution and a high signal-to-noise ratio. Motion artifacts were reduced with BARP, as compared with those with random blinking. Intraocular structures such as the iris and ciliary muscles were clearly visualized. Because the whole eye can be covered with a 1-mm thickness by this method, three-dimensional maps can easily be generated from the obtained images.


CONCLUSIONS
The application of BARP with a surface coil of the human eye might become a useful and widely adopted procedure for MR microimaging.
Obata
Takayuki
T
Department of Medical Imaging, National Institute of Radiological Sciences, Chiba 263-8555, Japan. t_obata@nirs.go.jp
Uemura
Koji
K
Nonaka
Hiroi
H
Tamura
Mitsuru
M
Tanada
Shuji
S
Ikehira
Hiroo
H
D000465:Algorithms; D016477:Artifacts; D001767:Blinking / Q000502:physiology*; D005143:Eyelids / Q000502:physiology*; D019416:Head Movements; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D009799:Ocular Physiological Phenomena