The use of parallel imaging for MRI assessment of knees in children and adolescents.
BACKGROUND
Parallel imaging provides faster scanning at the cost of reduced signal-to-noise ratio (SNR) and increased artifacts.


OBJECTIVE
To compare the diagnostic performance of two parallel MRI protocols (PPs) for assessment of pathologic knees using an 8-channel knee coil (reference standard, conventional protocol [CP]) and to characterize the SNR losses associated with parallel imaging.


METHODS
Two radiologists blindly interpreted 1.5 Tesla knee MRI images in 21 children (mean 13 years, range 9-18 years) with clinical indications for an MRI scan. Sagittal proton density, T2-W fat-saturated FSE, axial T2-W fat-saturated FSE, and coronal T1-W (NEX of 1,1,1) images were obtained with both CP and PP. Images were read for soft tissue and osteochondral findings.


RESULTS
There was a 75% decrease in acquisition time using PP in comparison to CP. The CP and PP protocols fell within excellent or upper limits of substantial agreement: CP, kappa coefficient, 0.81 (95% CIs, 0.73-0.89); PP, 0.80-0.81 (0.73-0.89). The sensitivity of the two PPs was similar for assessment of soft (0.98-1.00) and osteochondral (0.89-0.94) tissues. Phantom data indicated an SNR of 1.67, 1.6, and 1.51 (axial, sagittal and coronal planes) between CP and PP scans.


CONCLUSIONS
Parallel MRI provides a reliable assessment for pediatric knees in a significantly reduced scan time without affecting the diagnostic performance of MRI.
Doria
Andrea S
AS
Department of Diagnostic Imaging, Toronto, Canada. andrea.doria@sickkids.ca
Chaudry
Gulraiz A
GA
Nasui
Cristina
C
Rayner
Tammy
T
Wang
Chenghua
C
Moineddin
Rahim
R
Babyn
Paul S
PS
White
Larry M
LM
Sussman
Marshall S
MS
D000293:Adolescent; D000465:Algorithms; D002648:Child; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007592:Joint Diseases / Q000473:pathology*; D007718:Knee Injuries / Q000473:pathology*; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D013997:Time Factors