7 Tesla MR imaging of the human eye in vivo.
OBJECTIVE
To develop a protocol which optimizes contrast, resolution and scan time for three-dimensional (3D) imaging of the human eye in vivo using a 7 Tesla (T) scanner and custom radio frequency (RF) coil.


METHODS
Initial testing was conducted to reduce motion and susceptibility artifacts. Three-dimensional FFE and IR-TFE images were obtained with variable flip angles and TI times. T(1) measurements were made and numerical simulations were performed to determine the ideal contrast of certain ocular structures. Studies were performed to optimize resolution and signal-to-noise ratio (SNR) with scan times from 20 s to 5 min.


RESULTS
Motion and susceptibility artifacts were reduced through careful subject preparation. T(1) values of the ocular structures are in line with previous work at 1.5T. A voxel size of 0.15 x 0.25 x 1.0 mm(3) was obtained with a scan time of approximately 35 s for both 3D FFE and IR-TFE sequences. Multiple images were registered in 3D to produce final SNRs over 40.


CONCLUSIONS
Optimization of pulse sequences and avoidance of susceptibility and motion artifacts led to high quality images with spatial resolution and SNR exceeding prior work. Ocular imaging at 7T with a dedicated coil improves the ability to make measurements of the fine structures of the eye.
Richdale
Kathryn
K
The Ohio State University College of Optometry, Columbus, Ohio, USA.
Wassenaar
Peter
P
Teal Bluestein
Katharine
K
Abduljalil
Amir
A
Christoforidis
John A
JA
Lanz
Titus
T
Knopp
Michael V
MV
Schmalbrock
Petra
P
D000328:Adult; D016477:Artifacts; D003952:Diagnostic Imaging / Q000379:methods; D005123:Eye / Q000033:anatomy & histology* / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics; D008875:Middle Aged; D008962:Models, Theoretical; D009038:Motion; D011305:Presbyopia / Q000175:diagnosis* / Q000473:pathology*; D013997:Time Factors