Real-time interactive MR imaging system: sequence optimization, and basic and clinical evaluations.
A real-time interactive MR imaging system (real-time MRI) is an MR scanner which has a fast image updating cycle and the ability to freely change slice orientation, just like an ultrasound imaging system. Recently, such a system has been developed and installed on a clinical 1.5-Tesla system. The purpose of this study was to optimize the pulse sequences for clinical use and to evaluate the clinical usefulness and basic functionality of real-time MRI. For T1-weighted imaging, FLASH (fast low angle shot) can be selected, and up to 5 frames per second can be acquired depending on the matrix size. For T2-weighted imaging, true FISP (fast imaging with steady-state precession) can be selected, and up to 4 frames per second can be acquired. Maximum C/N between liver and spleen was obtained at a flip angle of 20 degrees on FLASH. Maximum C/N between cardiac cavity and wall was obtained at a flip angle of 60 degrees on true FISP. Localization of the right and left coronary arteries could be performed within 30 seconds in three volunteers. Although the present real-time MRI system has drawbacks such as low spatial resolution and relatively low contrast resolution, we expect real-time MRI to be one of the most important tools for future clinical MRI.
Naganawa
S
S
Department of Radiology, Nagoya University School of Medicine, Japan.
Ishiguchi
T
T
Ishigaki
T
T
Sato
K
K
Katagiri
T
T
Kishimoto
H
H
Mimura
T
T
Takizawa
O
O
Imura
C
C
D000328:Adult; D016477:Artifacts; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis; D003199:Computer Systems; D003287:Contrast Media; D003331:Coronary Vessels / Q000033:anatomy & histology; D003679:Deglutition / Q000502:physiology; D004867:Equipment Design; D005069:Evaluation Studies as Topic; D005133:Eye Movements / Q000502:physiology; D006321:Heart / Q000033:anatomy & histology; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D008099:Liver / Q000033:anatomy & histology; D008113:Liver Neoplasms / Q000175:diagnosis; D018810:Magnetic Resonance Angiography / Q000295:instrumentation / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D009917:Orbital Fractures / Q000503:physiopathology; D012815:Signal Processing, Computer-Assisted; D013154:Spleen / Q000033:anatomy & histology; D001743:Urinary Bladder / Q000502:physiology; D014554:Urination / Q000502:physiology
D003287:Contrast Media