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High spatial and temporal resolution retrospective cine cardiovascular magnetic resonance from shortened free breathing real-time acquisitions.

Xue H, Kellman P, Larocca G, Arai AE, Hansen MS - J Cardiovasc Magn Reson (2013)

Bottom Line: Volumetric measurements of cardiac function were also compared by manually tracing the myocardium for segmented and retrospective cines.No significant differences were seen in end-diastolic volume (P = 0.460/0.268) but there was a trend towards a small overestimation of end-systolic volume of 2.0/2.5 ml, which did not reach statistical significance (P = 0.052/0.083).Further speedup of image reconstruction is still needed.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Heart, Lung and Blood Institute, National Institutes of Health, 10 Center Drive, Bethesda, MD 20814, USA. hui.xue@nih.gov.

ABSTRACT

Background: Cine cardiovascular magnetic resonance (CMR) is challenging in patients who cannot perform repeated breath holds. Real-time, free-breathing acquisition is an alternative, but image quality is typically inferior. There is a clinical need for techniques that achieve similar image quality to the segmented cine using a free breathing acquisition. Previously, high quality retrospectively gated cine images have been reconstructed from real-time acquisitions using parallel imaging and motion correction. These methods had limited clinical applicability due to lengthy acquisitions and volumetric measurements obtained with such methods have not previously been evaluated systematically.

Methods: This study introduces a new retrospective reconstruction scheme for real-time cine imaging which aims to shorten the required acquisition. A real-time acquisition of 16-20s per acquired slice was inputted into a retrospective cine reconstruction algorithm, which employed non-rigid registration to remove respiratory motion and SPIRiT non-linear reconstruction with temporal regularization to fill in missing data. The algorithm was used to reconstruct cine loops with high spatial (1.3-1.8 × 1.8-2.1 mm²) and temporal resolution (retrospectively gated, 30 cardiac phases, temporal resolution 34.3 ± 9.1 ms). Validation was performed in 15 healthy volunteers using two different acquisition resolutions (256 × 144/192 × 128 matrix sizes). For each subject, 9 to 12 short axis and 3 long axis slices were imaged with both segmented and real-time acquisitions. The retrospectively reconstructed real-time cine images were compared to a traditional segmented breath-held acquisition in terms of image quality scores. Image quality scoring was performed by two experts using a scale between 1 and 5 (poor to good). For every subject, LAX and three SAX slices were selected and reviewed in the random order. The reviewers were blinded to the reconstruction approach and acquisition protocols and scores were given to segmented and retrospective cine series. Volumetric measurements of cardiac function were also compared by manually tracing the myocardium for segmented and retrospective cines.

Results: Mean image quality scores were similar for short axis and long axis views for both tested resolutions. Short axis scores were 4.52/4.31 (high/low matrix sizes) for breath-hold vs. 4.54/4.56 for real-time (paired t-test, P = 0.756/0.011). Long axis scores were 4.09/4.37 vs. 3.99/4.29 (P = 0.475/0.463). Mean ejection fraction was 60.8/61.4 for breath-held acquisitions vs. 60.3/60.3 for real-time acquisitions (P = 0.439/0.093). No significant differences were seen in end-diastolic volume (P = 0.460/0.268) but there was a trend towards a small overestimation of end-systolic volume of 2.0/2.5 ml, which did not reach statistical significance (P = 0.052/0.083).

Conclusions: Real-time free breathing CMR can be used to obtain high quality retrospectively gated cine images in 16-20s per slice. Volumetric measurements and image quality scores were similar in images from breath-held segmented and free breathing, real-time acquisitions. Further speedup of image reconstruction is still needed.

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An example of segmented cine degraded with imperfect breath-holding (right column), while the retrospective real-time cine (left column) gives good results. Besides being tedious and time-consuming, the repeated breath-holding in the segmented cine also complicates the scanning procedure and reduces the robustness. Both ES (upper row) and ED phases (lower row) are shown.
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Figure 7: An example of segmented cine degraded with imperfect breath-holding (right column), while the retrospective real-time cine (left column) gives good results. Besides being tedious and time-consuming, the repeated breath-holding in the segmented cine also complicates the scanning procedure and reduces the robustness. Both ES (upper row) and ED phases (lower row) are shown.

Mentions: The segmented cine can be degraded if the breath-holding is compromised. Figure 7 gives an example of imperfect segmented cine, while the real-time retrospective reconstruction shows good image quality. Here both segmented and real-time cine were acquired at the identical slice location and orientation (Additional file 8: Figure S7.avi).


High spatial and temporal resolution retrospective cine cardiovascular magnetic resonance from shortened free breathing real-time acquisitions.

Xue H, Kellman P, Larocca G, Arai AE, Hansen MS - J Cardiovasc Magn Reson (2013)

An example of segmented cine degraded with imperfect breath-holding (right column), while the retrospective real-time cine (left column) gives good results. Besides being tedious and time-consuming, the repeated breath-holding in the segmented cine also complicates the scanning procedure and reduces the robustness. Both ES (upper row) and ED phases (lower row) are shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3842803&req=5

Figure 7: An example of segmented cine degraded with imperfect breath-holding (right column), while the retrospective real-time cine (left column) gives good results. Besides being tedious and time-consuming, the repeated breath-holding in the segmented cine also complicates the scanning procedure and reduces the robustness. Both ES (upper row) and ED phases (lower row) are shown.
Mentions: The segmented cine can be degraded if the breath-holding is compromised. Figure 7 gives an example of imperfect segmented cine, while the real-time retrospective reconstruction shows good image quality. Here both segmented and real-time cine were acquired at the identical slice location and orientation (Additional file 8: Figure S7.avi).

Bottom Line: Volumetric measurements of cardiac function were also compared by manually tracing the myocardium for segmented and retrospective cines.No significant differences were seen in end-diastolic volume (P = 0.460/0.268) but there was a trend towards a small overestimation of end-systolic volume of 2.0/2.5 ml, which did not reach statistical significance (P = 0.052/0.083).Further speedup of image reconstruction is still needed.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Heart, Lung and Blood Institute, National Institutes of Health, 10 Center Drive, Bethesda, MD 20814, USA. hui.xue@nih.gov.

ABSTRACT

Background: Cine cardiovascular magnetic resonance (CMR) is challenging in patients who cannot perform repeated breath holds. Real-time, free-breathing acquisition is an alternative, but image quality is typically inferior. There is a clinical need for techniques that achieve similar image quality to the segmented cine using a free breathing acquisition. Previously, high quality retrospectively gated cine images have been reconstructed from real-time acquisitions using parallel imaging and motion correction. These methods had limited clinical applicability due to lengthy acquisitions and volumetric measurements obtained with such methods have not previously been evaluated systematically.

Methods: This study introduces a new retrospective reconstruction scheme for real-time cine imaging which aims to shorten the required acquisition. A real-time acquisition of 16-20s per acquired slice was inputted into a retrospective cine reconstruction algorithm, which employed non-rigid registration to remove respiratory motion and SPIRiT non-linear reconstruction with temporal regularization to fill in missing data. The algorithm was used to reconstruct cine loops with high spatial (1.3-1.8 × 1.8-2.1 mm²) and temporal resolution (retrospectively gated, 30 cardiac phases, temporal resolution 34.3 ± 9.1 ms). Validation was performed in 15 healthy volunteers using two different acquisition resolutions (256 × 144/192 × 128 matrix sizes). For each subject, 9 to 12 short axis and 3 long axis slices were imaged with both segmented and real-time acquisitions. The retrospectively reconstructed real-time cine images were compared to a traditional segmented breath-held acquisition in terms of image quality scores. Image quality scoring was performed by two experts using a scale between 1 and 5 (poor to good). For every subject, LAX and three SAX slices were selected and reviewed in the random order. The reviewers were blinded to the reconstruction approach and acquisition protocols and scores were given to segmented and retrospective cine series. Volumetric measurements of cardiac function were also compared by manually tracing the myocardium for segmented and retrospective cines.

Results: Mean image quality scores were similar for short axis and long axis views for both tested resolutions. Short axis scores were 4.52/4.31 (high/low matrix sizes) for breath-hold vs. 4.54/4.56 for real-time (paired t-test, P = 0.756/0.011). Long axis scores were 4.09/4.37 vs. 3.99/4.29 (P = 0.475/0.463). Mean ejection fraction was 60.8/61.4 for breath-held acquisitions vs. 60.3/60.3 for real-time acquisitions (P = 0.439/0.093). No significant differences were seen in end-diastolic volume (P = 0.460/0.268) but there was a trend towards a small overestimation of end-systolic volume of 2.0/2.5 ml, which did not reach statistical significance (P = 0.052/0.083).

Conclusions: Real-time free breathing CMR can be used to obtain high quality retrospectively gated cine images in 16-20s per slice. Volumetric measurements and image quality scores were similar in images from breath-held segmented and free breathing, real-time acquisitions. Further speedup of image reconstruction is still needed.

Show MeSH
Related in: MedlinePlus