Ultrasound‐guided identification of cardiac imaging windows

Liu, Garry; Qi, Xiuling; Robert, Normand; Dick, Alexander; Wright, Graham A.

doi:10.1118/1.4711757

Cited by 16 publications

(15 citation statements)

References 23 publications

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“…Different epicardial regions have been known to have different diastasis timings [4,5,16]. The Septal Scout is more suitable for whole-heart angiography; basal septal diastasis is an accurate surrogate for ventricular diastasis [9]. To our knowledge, there has not been work presented on the CMR monitoring of septal motion for determining cardiac gating windows.…”

Section: Discussionmentioning

confidence: 99%

“…In particular, it observes the expansion and compression of the basal interventricular septum (IVS) along the long axis of the heart, which has been found to correlate with global epicardial motion [9]. The high temporal resolution is achieved by foregoing one dimension of spatial encoding.…”

Section: Methodsmentioning

confidence: 99%

“…It has been shown that tissue Doppler echocardiography (TDE) of the IVS was able to identify accurate coronary artery diastasis windows [9]. The first six subjects in this study formed a subcohort for comparing the Septal Scout to the TDE technique with respect to the timing estimation of diastasis windows.…”

Section: Methodsmentioning

confidence: 99%

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Cardiac gating calibration by the Septal Scout for magnetic resonance coronary angiography

Liu

Wright

2014

Journal of Cardiovascular Magnetic Resonance

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BackgroundElectrocardiogram (ECG) gating is commonly used to synchronize imaging windows to diastasis periods over multiple heartbeats in magnetic resonance (MR) coronary angiography. Calibration of the ECG gating parameters is typically based on a cine cardiovascular MR (CMR) video of the beating heart. Insufficient temporal resolution in the cine-CMR method, however, may produce gating errors and motion artifacts.It was previously shown that tissue Doppler echocardiography (TDE) can identify accurate diastasis window timings by observing the movement of the interventricular septum (IVS). We present a new CMR technique, the Septal Scout, for measuring IVS motion. We demonstrate that cardiac gating windows determined by the Septal Scout produce sharper coronary MR angiography images than windows determined by cine-CMR.Methods9 healthy volunteers were scanned on a GE Optima 450w 1.5T MR system. Cine-CMR was acquired and used to identify the start and end times of the diastasis window (Wcine).The Septal Scout employs a one-dimensional steady-state free precession (SSFP) readout along the ventricular septum prescribed from the 4-chamber view. The Septal Scout data is processed to produce a septal velocity function, from which the diastasis window was determined (Wsep).Non-contrast-enhanced MR angiography was performed twice for each volunteer: once gated to Wcine, once to Wsep. Vessel sharpness was assessed subjectively by two experienced observers, and quantitatively by full width half maximum (FWHM) measurements of cross-sectional vessel profiles.In addition, TDE was performed on a subcohort of 6 volunteers where diastasis windows (WTDE) were determined from the IVS velocity measured in the 4-chamber view. W sep and W TDE were compared using Pearson’s correlation.ResultsMRA acquisitions were successful in all volunteers. Vessel segments produced smaller FWHM measurements and were deemed sharper when imaged during the Septal Scout gating windows (p < 0.05). Subjective assessment of sharpness also improved for the Septal Scout-gated scans (p < 0.01 for both observers). Lastly, W sep and W TDE were highly correlated (R > 0.98, p < 0.001).ConclusionsThe MR Septal Scout technique was introduced and demonstrated to be more accurate at determining cardiac gating windows than cine-CMR, yielding sharper coronary MR angiography images.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Cardiac gating calibration by the Septal Scout for magnetic resonance coronary angiography

Liu

Wright

2014

Journal of Cardiovascular Magnetic Resonance

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“…Liu et al showed that the IVS was an accurate predictor of LAD vessel quiescence. 16 From Table III, the LAD is in fact among the least similar to the IVS, suggesting that if the IVS is a suitable predictor for the LAD it will be as good or better for the other vessels. The quiescence of the IVS is of particular interest because it can be readily observed using echocardiography, as opposed to the coronary vessels.…”

Section: Discussionmentioning

confidence: 99%

Characterization of cardiac quiescence from retrospective cardiac computed tomography using a correlation‐based phase‐to‐phase deviation measure

et al. 2015

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Purpose: Accurate knowledge of cardiac quiescence is crucial to the performance of many cardiac imaging modalities, including computed tomography coronary angiography (CTCA). To accurately quantify quiescence, a method for detecting the quiescent periods of the heart from retrospective cardiac computed tomography (CT) using a correlation-based, phase-to-phase deviation measure was developed. Methods: Retrospective cardiac CT data were obtained from 20 patients (11 male, 9 female, 33-74 yr) and the left main, left anterior descending, left circumflex, right coronary artery (RCA), and interventricular septum (IVS) were segmented for each phase using a semiautomated technique. Cardiac motion of individual coronary vessels as well as the IVS was calculated using phase-to-phase deviation. As an easily identifiable feature, the IVS was analyzed to assess how well it predicts vessel quiescence. Finally, the diagnostic quality of the reconstructed volumes from the quiescent phases determined using the deviation measure from the vessels in aggregate and the IVS was compared to that from quiescent phases calculated by the CT scanner. Three board-certified radiologists, fellowship-trained in cardiothoracic imaging, graded the diagnostic quality of the reconstructions using a Likert response format: 1 = excellent, 2 = good, 3 = adequate, 4 = nondiagnostic. Results: Systolic and diastolic quiescent periods were identified for each subject from the vessel motion calculated using the phase-to-phase deviation measure. The motion of the IVS was found to be similar to the aggregate vessel (AGG) motion. The diagnostic quality of the coronary vessels for the quiescent phases calculated from the aggregate vessel (P AGG ) and IVS (P IVS ) deviation signal using the proposed methods was comparable to the quiescent phases calculated by the CT scanner (P CT ). The one exception was the RCA, which improved for P AGG for 18 of the 20 subjects when compared to P CT (P CT = 2.48; P AGG = 2.07, p = 0.001). Conclusions: A method for quantifying the motion of specific coronary vessels using a correlationbased, phase-to-phase deviation measure was developed and tested on 20 patients receiving cardiac CT exams. The IVS was found to be a suitable predictor of vessel quiescence. The diagnostic quality of the quiescent phases detected by the proposed methods was comparable to those calculated by the CT scanner. The ability to quantify coronary vessel quiescence from the motion of the IVS can be used to develop new CTCA gating techniques and quantify the resulting potential improvement in CTCA image quality. C 2015 American Association of Physicists in Medicine.

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“…An accurate timing determination for whole-heart coronary imaging can be difficult in such subjects, as the heart rate can vary from beat to beat over the duration of a long scan, or change significantly in the presence or absence of breath-holding. In addition to the per-patient and physiological variability, the optimal period quiescent period with minimal motion for each artery branch may vary by anatomical position [10,11]. Therefore, a single acquisition window may not necessarily be optimally timed for each coronary artery branch and region.…”

Section: Introductionmentioning

confidence: 99%

Whole Heart Coronary Imaging with Flexible Acquisition Window and Trigger Delay

et al. 2015

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Coronary magnetic resonance imaging (MRI) requires a correctly timed trigger delay derived from a scout cine scan to synchronize k-space acquisition with the quiescent period of the cardiac cycle. However, heart rate changes between breath-held cine and free-breathing coronary imaging may result in inaccurate timing errors. Additionally, the determined trigger delay may not reflect the period of minimal motion for both left and right coronary arteries or different segments. In this work, we present a whole-heart coronary imaging approach that allows flexible selection of the trigger delay timings by performing k-space sampling over an enlarged acquisition window. Our approach addresses coronary motion in an interactive manner by allowing the operator to determine the temporal window with minimal cardiac motion for each artery region. An electrocardiogram-gated, k-space segmented 3D radial stack-of-stars sequence that employs a custom rotation angle is developed. An interactive reconstruction and visualization platform is then employed to determine the subset of the enlarged acquisition window for minimal coronary motion. Coronary MRI was acquired on eight healthy subjects (5 male, mean age = 37 ± 18 years), where an enlarged acquisition window of 166–220 ms was set 50 ms prior to the scout-derived trigger delay. Coronary visualization and sharpness scores were compared between the standard 120 ms window set at the trigger delay, and those reconstructed using a manually adjusted window. The proposed method using manual adjustment was able to recover delineation of five mid and distal right coronary artery regions that were otherwise not visible from the standard window, and the sharpness scores improved in all coronary regions using the proposed method. This paper demonstrates the feasibility of a whole-heart coronary imaging approach that allows interactive selection of any subset of the enlarged acquisition window for a tailored reconstruction for each branch region.

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Ultrasound‐guided identification of cardiac imaging windows

Cited by 16 publications

References 23 publications

Cardiac gating calibration by the Septal Scout for magnetic resonance coronary angiography

Cardiac gating calibration by the Septal Scout for magnetic resonance coronary angiography

Characterization of cardiac quiescence from retrospective cardiac computed tomography using a correlation‐based phase‐to‐phase deviation measure

Whole Heart Coronary Imaging with Flexible Acquisition Window and Trigger Delay

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