Rapid left-to-right shunt quantification in children by phase-contrast magnetic resonance imaging combined with sensitivity encoding (SENSE).
BACKGROUND
Parallel imaging by sensitivity encoding (SENSE) may considerably reduce scan time in MRI. For rapid flow quantification in children with congenital heart disease, we evaluated phase-contrast MRI (PC-MRI) techniques combined with SENSE.


RESULTS
In 22 pediatric patients (mean age, 7.2+/-6.2 years) with cardiac left-to-right shunt, blood flow rate in the pulmonary artery (Qp) and ascending aorta (Qs) and flow ratio Qp/Qs were determined by PC-MRI with SENSE reduction-factor 2 and 3 (SF-2 and SF-3). Additionally, we used PC-MRI with higher spatial in-plane resolution (1.6x2.1 versus 2.3x3.1 mm) with and without SF-3. Results were compared with a recently validated standard PC-MRI protocol and tested in vitro using a pulsatile flow phantom. Reduction of signal averages from 2 to 1 and application of SENSE accelerated flow measurements by a factor of 3.5 (5.2) using PC-MRI with SF-2 (SF-3) compared with standard PC-MRI. For blood flow rate through the pulmonary artery and aorta, as well as for the Qp/Qs ratio we found negligible differences of +/-3%, lower limits of agreement (mean+/-2 SD) of -7% to -18%, and upper limits of agreement (mean+/-2 SD) of +3 to +24%, demonstrating good agreement with standard PC-MRI. Mean Qp/Qs ratio by standard PC-MRI was 1.69+/-0.45 (range, 1.27 to 2.79). Interobserver variability was low, and high accuracy was confirmed in vitro for all protocols.


CONCLUSIONS
PC-MRI for flow quantitation may be combined with SENSE to achieve a substantive reduction of scanning time. In children with left-to-right shunt, Qp/Qs quantification is possible by PC-MRI+SF-3 in <60 seconds. Use of higher in-plane resolution did not improve measurement results.
Beerbaum
Philipp
P
Klinik für Angeborene Herzfehler, Herz- und Diabeteszentrum, Nordrhein-Westfalen, Ruhr-Universität Bochum, Germany. pbeerbaum@hdz-nrw.de
Körperich
Hermann
H
Gieseke
Jürgen
J
Barth
Peter
P
Peuster
Matthias
M
Meyer
Hans
H
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003326:Coronary Circulation; D005260:Female; D006330:Heart Defects, Congenital / Q000175:diagnosis*; D006801:Humans; D007223:Infant; D019028:Magnetic Resonance Imaging, Cine / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D008297:Male; D015588:Observer Variation; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors