T2-Weighted fast MR imaging with true FISP versus HASTE: comparative efficacy in the evaluation of normal fetal brain maturation.
OBJECTIVE
This study compares the relative efficacy of two fast T2-weighted MR imaging techniques-fast imaging with steady-state free precession (true FISP) and half-Fourier acquisition single-shot turbo spin-echo (HASTE)-in the evaluation of the normal fetal brain maturation during the second and third trimesters of gestation.


METHODS
The brain maturation of 10 normal nonsedated fetuses (5 during the second trimester and 6 during the third trimester of gestation [1 fetus underwent 2 examinations]) was examined by both techniques using a Vision+ 1.5-T MR system. We specifically looked for developing events, including white matter myelination, neuronal migration, and cortical sulcation. Image quality was graded according to the presence or absence of undesirable blurring.


RESULTS
The specific absorption rate was lower for true FISP than for HASTE by a factor of 3 at equivalent imaging conditions. HASTE and true FISP provide comparable image quality in the second trimester when myelination of the cerebrum has not begun. Neuronal migration could be recognized as hypodense bands on both sequences during the second trimester. Myelination beginning at the third trimester was better delineated with true FISP than with HASTE because of point spread function-related blurring effects inherent in HASTE that hampered visualization of short-T2 structures. Cortical sulcation was well delineated by both sequences.


CONCLUSIONS
With relatively superior image quality and significantly lower radiofrequency absorption than HASTE, true FISP is a safer and more effective alternative in the prenatal evaluation of normal fetal brain.
Chung
H W
HW
Department of Electrical Engineering, National Taiwan University, No. 1, Section 4, Roosevelt Rd., Taipei, Taiwan 10764, Republic of China.
Chen
C Y
CY
Zimmerman
R A
RA
Lee
K W
KW
Lee
C C
CC
Chin
S C
SC
D001479:Basal Ganglia / Q000196:embryology; D001921:Brain / Q000196:embryology*; D001933:Brain Stem / Q000196:embryology; D002465:Cell Movement / Q000502:physiology; D002540:Cerebral Cortex / Q000196:embryology; D005314:Embryonic and Fetal Development; D005260:Female; D005865:Gestational Age; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009186:Myelin Sheath / Q000502:physiology; D009474:Neurons / Q000502:physiology; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D012449:Safety; D013788:Thalamus / Q000196:embryology