The Alestle - Vol. 54 No. 42 - 02/21/2002

Vol. 54 No. 4

Civil Procedure--In Personam Actions and the Nonresident Motorist Statutes

International audienc

Determination of the myocardial area at risk after reperfused acute myocardial infarction with different imaging techniques: cardiac magnetic resonance imaging, multidetector computed tomography and histopathological validation

International audiencen.

Early detection of myocardial fibrosis in type II diabetic patients using MR T1-mapping

ORAL PRESENTATIONInternational audienc

Myocardial T1-mapping for early detection of left ventricular myocardial fibrosis in systemic sclerosis

International audiencen.

Improved reproducibility for myocardial ASL: Impact of physiological and acquisition parameters

PURPOSE: To investigate and mitigate the influence of physiological and acquisition-related parameters on myocardial blood flow (MBF) measurements obtained with myocardial Arterial Spin Labeling (myoASL). METHODS: A Flow-sensitive Alternating Inversion Recovery (FAIR) myoASL sequence with bSSFP and spoiled GRE (spGRE) readout is investigated for MBF quantification. Bloch-equation simulations and phantom experiments were performed to evaluate how variations in acquisition flip angle (FA), acquisition matrix size (AMS), heart rate (HR) and blood T 1 $${\mathrm{T}}_1$$ relaxation time ( T 1 , B $${\mathrm{T}}_{1,B}$$ ) affect quantification of myoASL-MBF. In vivo myoASL-images were acquired in nine healthy subjects. A corrected MBF quantification approach was proposed based on subject-specific T 1 , B $${\mathrm{T}}_{1,B}$$ values and, for spGRE imaging, subtracting an additional saturation-prepared baseline from the original baseline signal. RESULTS: Simulated and phantom experiments showed a strong dependence on AMS and FA ( R 2 $${R}^2$$ >0.73), which was eliminated in simulations and alleviated in phantom experiments using the proposed saturation-baseline correction in spGRE. Only a very mild HR dependence ( R 2 $${R}^2$$ >0.59) was observed which was reduced when calculating MBF with individual T 1 , B $${\mathrm{T}}_{1,B}$$ . For corrected spGRE, in vivo mean global spGRE-MBF ranged from 0.54 to 2.59 mL/g/min and was in agreement with previously reported values. Compared to uncorrected spGRE, the intra-subject variability within a measurement (0.60 mL/g/min), between measurements (0.45 mL/g/min), as well as the inter-subject variability (1.29 mL/g/min) were improved by up to 40% and were comparable with conventional bSSFP. CONCLUSION: Our results show that physiological and acquisition-related factors can lead to spurious changes in myoASL-MBF if not accounted for. Using individual T 1 , B $${\mathrm{T}}_{1,B}$$ and a saturation-baseline can reduce these variations in spGRE and improve reproducibility of FAIR-myoASL against acquisition parameters