Novel highly accelerated real-time CINE-MRI featuring compressed sensing with k-t regularization in comparison to TSENSE segmented and real-time Cine imaging
verfasst von:
Michaela Schmidt, Okan Ekinci, Jun Liu, Alban Lefebvre, Mariappan S Nadar, Edgar Mueller, Michael O Zenge
In patients with breath-holding difficulties or arrhythmia, real-time CINE-MRI is preferred over segmented acquisitions in one breath-hold. However, common real-time sequences require a deteriorating trade-off between spatial and temporal resolution. In the current work, highly accelerated real-time CINE-MRI which features compressed sensing with k t regularization [1] was evaluated against segmented and real-time imaging with TSENSE in healthy volunteers as a potential alternative providing both high spatial and temporal resolution in real time.
Methods
Sparse and incoherent sampling was implemented in a bSSFP 2D CINE-MRI sequence and a compressed sensing image reconstruction program featuring k-t regularization was provided. Thirteen healthy volunteers (7m/6f, age 43±17y, BMI 24±6.6) underwent CMR imaging on a 1.5T system (MAGNETOM Aera, Siemens AG, Erlangen, Germany). 2-/3-/4-chamber as well as 3 short-axis views were acquired with a fixed temporal resolution of 33 ms but different net acceleration factors (NAF) and acquisition durations (acq) based on the used sequences:
The acquired (reconstructed) voxel sizes were 2.4 x 1.7 x 6 mm3 (1.7 x 1.7 x 6 mm3), except for rtTSENSE4 with 6.0 x 3.0 x 6 mm3 (3.0 x 3.0 x 6mm3). Image reconstruction was performed online. All images were qualitatively assessed by an experienced CMR reader on a five-point Likert scale (5-excellent, 1-non-diagnostic). Scoring was performed with respect to the overall image quality with focus on presence/severity of artifacts and the ability to visually assess global and regional myocardial function. A paired t-test was used to compare differences in image quality between the different sequences.
Figure 1
Example images of a short-axis and a 3-chamber view of volunteer 5 from left to right: sTSENSE2; sTSENSE4; rtTSENSE4; rtCS11
×
Results
In all subjects, 2D datasets could be successfully acquired. The mean RR interval was 934±116 ms, three volunteers had sinus arrhythmia or extra systoles. Table 1 illustrates the results of the quality assessment. In terms of quality score, benchmark was set by sTSENSE2 (4.7±0.5). rtCS11 was significantly better than rtTSENSE4 (3.6±0.7 vs. 2.7±0.6, p<0.0001) and comparable to the quality of sTSENSE4 (3.9±0.5, p=0.004). Quality-relevant artifacts were rather noise-related in sTSENSE4 and contour- as well as flow-related in rtCS11.
Table 1
Quality assessment
sTSENSE2
sTSENSE4
rtTSENSE4
rtCS11
Acq/temporal resolution
6hb/33 ms
3hb/33 ms
1hb/33 ms
1hb/33 ms
Spatial Resolution/SLT (mm)
2.4x1.7x6/6
2.4x1.7x6/6
6.0x3.0x3.0/6
2.4x1.7x6/6
Mean overall image quality
4.8±0.5
3.9±0.5
2.7±0.6
3.7±0.7
Comparison with rtCS11
p<0.001
p=0.004
p<0.001
Conclusions
As the image quality of rtCS11 was significantly better than in case of real-time TSENSE and close to that of sTSENSE4, the novel method may become a better alternative for the assessment of cardiac function in real time. Further studies in a clinical setting are required to assess the performance in challenging cases.
Funding
Siemens AG
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/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Novel highly accelerated real-time CINE-MRI featuring compressed sensing with k-t regularization in comparison to TSENSE segmented and real-time Cine imaging
verfasst von
Michaela Schmidt Okan Ekinci Jun Liu Alban Lefebvre Mariappan S Nadar Edgar Mueller Michael O Zenge
