- Poster presentation
- Open Access
Demonstration of velocity selective myocardial arterial spin labeling perfusion CMR
https://doi.org/10.1186/1532-429X-18-S1-P98
© Jao and Nayak 2016
- Published: 27 January 2016
Keywords
- Myocardial Blood Flow
- Arterial Spin Label
- Background Suppression
- Physiological Noise
- Transit Delay
Background
Arterial spin labeling of the heart has been shown to estimate myocardial perfusion and perfusion reserve at a single short-axis slice for coronary artery disease assessment. However, current spatial labeling methods suffer from transit delay effects when imaging is extended to more than a single slice. Velocity selective (VS) labeling is a promising alternative that does not suffer from transit delay effects.
Methods
A. the Velocity selective pulse is made using a symmetric BIR4 for reduced eddy current sensitivity and bipolar gradients to prevent spatial signal modulation in static tissue. B. Coronary arterial blood (red) is saturated by VS labeling at mid-diastole with a velocity cutoff of 10 cm/s. Left: Gz "off" (T2 weighting only) Right: Gz "on" (T2 weighting + velocity selective saturation).
Results
Figure 1B shows that the VS labeling pulse was successful in saturating blood within the coronary artery. MBF and PN measurements from VSASL and FAIR were 1.69 ± 0.84 ml/g/min and 2.22 ± 0.57 ml/g/min respectively in eight volunteers. This corresponds to a TSNR of 2.01 and 3.89 respectively. VSASL underestimated MBF by 23.8% when compared to FAIR, which may be due to a signal loss of 15% from inversion inefficiency in background suppression combined with a T2 signal loss of 7% from the 12 ms VS pulse. We suspect that higher PN in VSASL is from spurious labeling of myocardium, which can be further reduced by more consistent background suppression. Low TSNR will be addressed by further sequence improvements that explore different cutoff velocities and velocity labeling directions. In a single volunteer, we performed an additional FAIR experiment with a thicker inversion slab (FAIR-TS) to simulate whole heart coverage. MBF and PN measurements from VSASL, FAIR, and FAIR-TS were 1.38 ± 0.58 ml/g/min, 0.88 ± 0.37 ml/g/min, and -0.04 ± 0.24 ml/g/min respectively. FAIR-TS has a large transit delay and is unable to estimate MBF while VSASL does not suffer from transit delay effects.
Conclusions
MBF and PN measurements from VSASL, FAIR, and FAIR-TS with a thicker inversion slab to simulate whole heart coverage in a single volunteer. Both VSASL and FAIR are able to measure MBF. The region of high MBF on the lateral wall in VSASL is possibly due to spurious myocardial labeling. While VSASL has higher PN than FAIR, it is compatible with whole heart coverage because it does not suffer from transit delay effects. FAIR-TS is unable to measure MBF because the thickened inversion slab imparts a large transit delay.
Authors’ Affiliations
Copyright
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.