IMT Institutional Repository: No conditions. Results ordered -Date Deposited. 2024-03-28T09:41:26ZEPrintshttp://eprints.imtlucca.it/images/logowhite.pnghttp://eprints.imtlucca.it/2013-11-20T11:04:43Z2013-11-20T11:04:43Zhttp://eprints.imtlucca.it/id/eprint/1916This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/19162013-11-20T11:04:43ZDetecting Myocardial Ischemia at Rest With Cardiac Phase-Resolved Blood Oxygen Level-Dependent Cardiovascular Magnetic ResonanceBackground: Fast, noninvasive identification of ischemic territories at rest (prior to tissue-specific changes) and assessment of functional status can be valuable in the management of severe coronary artery disease. This study investigated the utility of cardiac phase-resolved Blood-Oxygen-Level-Dependent (CP-BOLD) CMR in detecting myocardial ischemia at rest secondary to severe coronary artery stenosis.
Methods and Results: CP-BOLD, standard-cine, and T2-weighted images were acquired in canines (n=11) at baseline and within 20 minutes of ischemia induction (severe LAD stenosis) at rest. Following 3-hours of ischemia, LAD stenosis was removed and T2-weighted and late-gadolinium-enhancement (LGE) images were acquired. From standard-cine and CP-BOLD images, End-Systolic (ES) and End-Diastolic (ED) myocardium were segmented. Affected and remote sections of the myocardium were identified from post-reperfusion LGE images. S/D, quotient of mean ES and ED signal intensities (on CP-BOLD and standard-cine), was computed for affected and remote segments at baseline and ischemia. Ejection fraction (EF) and segmental wall-thickening (sWT) were derived from CP-BOLD images at baseline and ischemia. On CP-BOLD images: S/D was greater than 1 (remote and affected territories) at baseline; S/D was diminished only in affected territories during ischemia and the findings were statistically significant (ANOVA, post-hoc p<0.01). The dependence of S/D on ischemia was not observed in standard-cine images. Computer simulations confirmed the experimental findings. ROC analysis showed that S/D identifies affected regions with similar performance (AUC:0.87) as EF (AUC:0.89) and sWT (AUC:0.75).
Conclusions: Preclinical studies and computer simulations showed that CP-BOLD CMR could be useful in detecting myocardial ischemia at rest. Patient studies are needed for clinical translation. Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRichard TangDebiao LiRohan Dharmakumar2013-03-06T11:22:15Z2013-03-12T09:32:21Zhttp://eprints.imtlucca.it/id/eprint/1518This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/15182013-03-06T11:22:15ZDetecting ACS and Identifying Acute Ischemic Territories with Cardiac Phase-Resolved BOLD MRI at RestSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRichard TangJ. MinDebiao LiRohan Dharmakumar2013-03-05T14:57:29Z2013-03-12T09:32:21Zhttp://eprints.imtlucca.it/id/eprint/1508This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/15082013-03-05T14:57:29ZDetecting Myocardial Ischemia at Rest with Cardiac Phase-Resolved BOLD CMRBackground—Fast, noninvasive identification of ischemic territories at rest (prior to tissue-specific changes) and assessment of functional status can be valuable in the management of severe coronary artery disease. This study investigated the utility of cardiac phase-resolved Blood-Oxygen-Level-Dependent (CP-BOLD) CMR in detecting myocardial ischemia at rest secondary to severe coronary artery stenosis.
Methods and Results—CP-BOLD, standard-cine, and T2-weighted images were acquired in canines (n=11) at baseline and within 20 minutes of ischemia induction (severe LAD stenosis) at rest. Following 3-hours of ischemia, LAD stenosis was removed and T2-weighted and late-gadolinium-enhancement (LGE) images were acquired. From standard-cine and CP-BOLD images, End-Systolic (ES) and End-Diastolic (ED) myocardium were segmented. Affected and remote sections of the myocardium were identified from post-reperfusion LGE images. S/D, quotient of mean ES and ED signal intensities (on CP-BOLD and standard-cine), was computed for affected and remote segments at baseline and ischemia. Ejection fraction (EF) and segmental wall-thickening (sWT) were derived from CP-BOLD images at baseline and ischemia. On CP-BOLD images: S/D was greater than 1 (remote and affected territories) at baseline; S/D was diminished only in affected territories during ischemia and the findings were statistically significant (ANOVA, post-hoc p<0.01). The dependence of S/D on ischemia was not observed in standard-cine images. Computer simulations confirmed the experimental findings. ROC analysis showed that S/D identifies affected regions with similar performance (AUC:0.87) as EF (AUC:0.89) and sWT (AUC:0.75).
Conclusions—Preclinical studies and computer simulations showed that CP-BOLD CMR could be useful in detecting myocardial ischemia at rest. Patient studies are needed for clinical translation. Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRichard TangDebiao LiRohan Dharmakumar2012-06-26T12:26:10Z2013-03-12T09:32:21Zhttp://eprints.imtlucca.it/id/eprint/1285This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/12852012-06-26T12:26:10ZIschemic extent as a biomarker for characterizing severity of coronary artery stenosis with blood oxygen-sensitive MRIPurpose:To investigate whether a statistical analysis of myocardial blood-oxygen-level-dependent (mBOLD) signal intensities can lead to the identification and quantification of the ischemic area supplied by the culprit artery.Materials and Methods:Cardiac BOLD images were acquired in a canine model (n = 9) with controllable LCX stenosis at rest and during adenosine infusion on a 1.5T clinical scanner. Statistical distributions of myocardial pixel-intensities derived from BOLD images were used to compute an area metric (ischemic extent, IE). True myocardial perfusion was estimated from microsphere analysis. IE was compared against a standard metric (segment-intensity-response, SIR). Additional animals (n = 3) were used to investigate the feasibility of the approach for identifying ischemic territories due to LAD stenosis from mBOLD images.Results:Regression analyses showed that IE and myocardial flow ratio between rest and adenosine infusion (MFR) were exponentially related (R2 > 0.70, P < 0.001, for end-systole and end-diastole), while SIR and MFR were linearly related to end-systole (R2 = 0.51, P < 0.04) and unrelated to end-diastole (R2 ≈ 0, P = 0.91). Receiver-operating-characteristic analysis that IE was superior to SIR for detecting critical stenosis (MFR ≤2) in end-systole and end-diastole. Feasibility studies on LAD narrowing demonstrated that the proposed approach could also identify oxygenation changes in the LAD territories.Conclusion:The proposed evaluation of cardiac BOLD magnetic resonance imaging (MRI) offers marked improvement in sensitivity and specificity for detecting critical coronary stenosis at 1.5T compared to the mean segmental intensity approach. Patient studies are now warranted to determine its clinical utility. Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itRichard TangXiangzhi ZhouDebiao LiRohan Dharmakumar2011-09-09T12:33:12Z2013-03-05T15:29:25Zhttp://eprints.imtlucca.it/id/eprint/853This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8532011-09-09T12:33:12ZDetecting myocardial ischemia at rest with cardiac phase-resolved BOLD MRI: early findingsVasodilatory stress is the standard paradigm for probing myocardial oxygenation (O2) changes due to coronary artery stenosis on the basis of BOLD MRI (1-3). However, since vasodilation is typically achieved with provocative stress, approaches that can identify the presence of stenosis on the basis of microvascular alterations at rest are highly desirable. It is known that myocardial blood volume (MBV) varies throughout the cardiac cycle; MBV increases during diastole and decreases during systole (4,5). It has also been shown that changes in MBV lead to increased O2
extraction by cardiomyocytes (6). Thus, MBV and O2 are expected to vary at different parts of the cardiac cycle. In particular, in diastole, it is expected that MBV and O2 extraction are maximal, while in systole, MBV and O2 extraction are minimal. In addition, as MBV increases, even at a stable level of O2, the number of deoxygenated hemoglobin molecules within a voxel increases, causing a proportionate elevation in the local magnetic field
inhomogeneities (7). Moreover, with increasing grade of stenosis, the MBV in the myocardial territory supplied by a stenotic artery increases in systole (8-11). Thus, the relative MBV and O2 changes between systole and diastole are expected to be different between myocardial territories supplied by healthy and stenotic coronary arteries. Moreover, it is also known that T1 of myocardium is dependent on MBV and that the apparent T2 is dependent on
blood O2. Since SSFP signals are approximately T2/T1 weighted, it is hypothesized that cardiac phase-resolved BOLD SSFP (CP-BOLD) (12) signal intensities at systole and diastole may reflect changes in MBV and blood O2. In addition, since stenosis leads to an increase in systolic MBV and is accompanied by a reduction in blood O2, it is hypothesized that systolic and diastolic CP-BOLD signal intensities may be used to detect the ischemic
territories at resting states. These hypotheses were tested with simulations and canine experiments.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itVeronica RundellXiangzhi ZhouYing LiuRichard TangDebiao LiRohan Dharmakumar2011-09-09T12:28:14Z2013-03-05T15:30:15Zhttp://eprints.imtlucca.it/id/eprint/852This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8522011-09-09T12:28:14ZAn area-based imaging biomarker for the characterization of coronary artery stenosis with blood oxygen-sensitive MRIBOLD MRI may be used for detecting myocardial oxygenation changes secondary to coronary artery stenosis (1-3). Under
pharmacological stress, the myocardial bed supplied by the stenotic coronary artery appears hypointense relative to healthy regions in BOLD images. Manual windowing (to visualize signal changes) and segmentation according to the American Heart Association’s (AHA) recommendation are often used to characterize the BOLD effect. However, current approaches for analyzing BOLD changes are suboptimal for detecting critical stenosis (reduction in perfusion reserve below 2:1). The purpose of this study is to test the hypothesis that, ARREAS (Area-based biomaRker for chaRactErizing coronAry Stenosis), an area-based statistical approach relying on the differences between rest and stress images, can characterize BOLD changes in end-systole and end-diastole with exquisite sensitivity and specificity. This hypothesis was tested in a canine model.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itRichard TangXiangzhi ZhouDebiao LiRohan Dharmakumar2011-09-08T13:52:30Z2013-03-05T15:29:49Zhttp://eprints.imtlucca.it/id/eprint/851This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8512011-09-08T13:52:30ZAn area-based imaging biomarker for characterizing coronary artery stenosis with myocardial BOLD MRIBOLD MRI may be used for detecting myocardial oxygenation changes secondary to coronary artery stenosis. However, current approaches for analyzing BOLD changes are suboptimal for detecting critical stenosis.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itRichard TangXiangzhi ZhouDebiao LiRohan Dharmakumar2011-09-08T13:34:01Z2013-03-05T15:32:18Zhttp://eprints.imtlucca.it/id/eprint/850This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8502011-09-08T13:34:01ZA fully-automated statistical method for characterization of flow artifact presence in cardiac MRIFlow artifacts in MR images can appear as ghosts within and outside the body cavity. Current approaches for optimizing sequences for suppressing such artifacts rely on expert scoring or on semi-automated methods for evaluation.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRohan Dharmakumar2011-09-08T12:42:01Z2013-03-05T15:39:18Zhttp://eprints.imtlucca.it/id/eprint/845This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8452011-09-08T12:42:01ZA new quantitative imaging biomarker for identifying critical coronary artery stenosis with myocardial BOLD MRIBlood-oxygen-level dependent (BOLD) MRI may be used for detecting myocardial oxygenation changes secondary to coronary artery stenosis (CAS). Under pharmacological stress, areas of the myocardium supplied by a stenotic coronary artery appear hypointense relative to healthy regions in BOLD images. The purpose of this work is to present a fundamentally new approach for visualizing and quantifying regional myocardial BOLD signal changes. This approach, tested in canines, relies on the statistical identification of myocardial pixels affected by CAS, correlates strongly with true flow measurements, and most importantly, leads to a significant increase in sensitivity to microvascular flow changes compared to previous approaches.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouDebiao LiRohan Dharmakumar2011-09-08T12:36:10Z2013-03-05T15:39:03Zhttp://eprints.imtlucca.it/id/eprint/844This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8442011-09-08T12:36:10ZAutomated assessment of ghost artifacts in MRIFlow artifacts in MR images can appear as image ghosts within and outside the body cavity. Technical improvements aimed at suppressing these image ghosts often rely on expert scoring (1,2) or on semi-automated methods demanding tissue segmentation and estimation of statistical properties of intensity distribution (3) to evaluate the efficacy of the methods. These approaches can be labor intensive, introduce observer bias, computationally demanding, and error-prone if tissue segmentation is used. Herein we propose two fully automated image-processing methods that rely on the statistical properties of background (noise) pixels to assess the presence of flow artifacts (appearing as image ghosts) without requiring tissue segmentation. The first method rapidly evaluates the presence of flow artifacts in a global fashion, while the second one provides a more detailed characterization
of the artifacts. We evaluate the proposed methods in the setting of cardiac phase-resolved myocardial blood-oxygen-level-dependent (BOLD) MRI where different cine SSFP imaging strategies are proposed for overcoming flow artifacts. Finally we assess the utility of our automated approaches against expert scoring results.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRohan Dharmakumar2011-09-08T11:59:34Z2013-03-05T15:39:32Zhttp://eprints.imtlucca.it/id/eprint/842This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8422011-09-08T11:59:34ZAutomated synchronization of cardiac phases for myocardial BOLD MRIIt is particularly important for the evaluation of cardiac phase-resolved myocardial blood-oxygen-level-dependent (BOLD) MRI studies, to robustly and reproducibly synchronize images from rest and stress studies. The possibility of visualizing BOLD signal changes in multiple cardiac phases is expected to increase the diagnostic confidence for identifying the affected myocardial territories. The purpose of this work is to develop automated statistical methods to facilitate in the robust and reproducible evaluation of cardiac phase-resolved myocardial BOLD MRI through temporal synchronization of rest and stress images acquired at different heart rates, without resorting to LV segmentation.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRichard TangRachel KleinAggelos K. KatsaggelosRohan Dharmakumar2011-09-08T10:12:47Z2013-03-05T15:32:32Zhttp://eprints.imtlucca.it/id/eprint/841This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8412011-09-08T10:12:47ZUnsupervised and reproducible image-based identification of cardiac phases in cine SSFP MRIA critical component in computing quantitative diagnostic metrics, such as ejection fraction, as well as, image segmentation and registration is the accurate identification of the end-systolic (ES) and end-diastolic (ED) frames in cardiac cine MRI. Reliable identification of ES is also important in cardiac phase-resolved myocardial blood-oxygen-level-dependent (BOLD) MRI studies (1). An assessment of changes in myocardial oxygenation requires BOLD images to be collected at rest and stress, which is typically induced with intravenous infusion of adenosine. ES images at both states are compared to assess the presence of coronary artery stenosis. To increase reproducibility and eliminate variability it is desirable to automate this procedure.
Most automated methods relying on trigger times do not account for anatomical correspondence, while methods based on identifying the minimum and maximum of the blood pool area in the Left Ventricle (LV) chamber, are computationally intensive, susceptible to noise, and require prior localization and segmentation of the LV. The purpose of this work is to develop automated methods to facilitate in the robust and reproducible evaluation of cardiac cine MRI studiesSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRichard TangRohan Dharmakumar2011-09-07T15:02:38Z2013-03-05T15:40:24Zhttp://eprints.imtlucca.it/id/eprint/839This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8392011-09-07T15:02:38ZMyocardial BOLD imaging using flow compensated 2D cine bSSFPRobust image quality is critical for reliable detection and evaluation of myocardial oxygenation changes with blood-oxygen-level-dependent (BOLD) imaging. Recently, balanced Steady-State Free Precession (bSSFP) methods have been employed to overcome image quality limitations associated
with myocardial BOLD methods. However, the long TRs required for optimal BOLD contrast can lead to unwanted flow/motion artifacts, ultimately compromising image quality. In this work we evaluate the utility of 2D first-order motion compensation scheme to minimize flow/motion artifacts in cardiac phase-resolved bSSFP BOLD imaging.Xiangzhi ZhouSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itYing LiuRichard TangRachel KleinSven ZuehlsdorffDebiao LiRohan Dharmakumar2011-09-07T14:58:10Z2013-03-05T15:39:59Zhttp://eprints.imtlucca.it/id/eprint/838This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8382011-09-07T14:58:10ZOn the origin of myocardial edema contrast in T2-STIR imagesAcute myocardial infarcts (AMI) are typically discriminated with T2-weighted short TI inversion recovery (STIR) with turbo spin echo (TSE) readouts [1], albeit with limited specificity [2]. Guided by the association that T2-STIR images identify AMI territories on the basis of edema-related T2 changes, even some of the recently proposed improvements [2,3] have relied on preferential sensitization of magnetization to T2- weighting. However, whether T2-STIR imaging itself may also be sensitive to other sources of image contrast have not been fully investigated. We hypothesize that in addition to T2-weighting, edema detection with T2-STIR imaging has substantial weighting from proton density (PD) changes.Xiangzhi ZhouVeronica RundellYing LiuRichard TangRachel KleinShivraman GiriSaurabh ShahSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itSven ZuehlsdorffOrlando SimonettiDebiao LiRohan Dharmakumar2011-09-07T14:48:43Z2013-03-05T15:39:46Zhttp://eprints.imtlucca.it/id/eprint/837This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8372011-09-07T14:48:43ZOn the mechanism of myocardial edema contrast in T2-STIR imagesAcute myocardial infarcts (AMI) are typically discriminated with T2-STIR imaging [1], albeit with limited specificity [2]. Guided by the association that T2-STIR images identify AMI territories on the basis of edema-related T2 changes, even some of the recently proposed improvements [2,3] have relied on preferential sensitization of magnetization to T2-weighting. However, whether T2-STIR imaging itself may also be sensitive to other sources of contrast have not been fully investigated.Xiangzhi ZhouVeronica RundellYing LiuRichard TangShivraman GiriSaurabh ShahSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itSven ZuehlsdorffOrlando SimonettiDebiao LiRohan Dharmakumar2011-09-07T14:28:53Z2013-03-05T15:44:49Zhttp://eprints.imtlucca.it/id/eprint/836This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8362011-09-07T14:28:53ZAutomated detection and quantification of microcirculatory oxygenation changes in the heartBlood-oxygen-level dependent (BOLD) MRI may be used for detecting myocardial oxygenation (MO) changes secondary to coronary artery stenosis (CAS). Under pharmacological stress, the myocardial territory affected by CAS appears hypointense relative to healthy regions in BOLD images.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRichard TangDebiao LiRohan Dharmakumar2011-09-07T14:23:16Z2013-03-05T15:40:11Zhttp://eprints.imtlucca.it/id/eprint/835This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8352011-09-07T14:23:16ZArtifacts-reduced 2D cine SSFP with flow compensation for myocardial BOLD imagingRobust image quality is critical for reliable detection and evaluation of myocardial oxygenation changes with blood-oxygen-level-dependent (BOLD) imaging. Recently, balanced SSFP methods have been employed to overcome image quality limitations associated with myocardial BOLD methods. However, the long TRs required for BOLD contrast, can lead to unwanted flow/motion artifacts, ultimately compromising image quality.Xiangzhi ZhouSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itYing LiuRichard TangRachel KleinSven ZuehlsdorffDebiao LiRohan Dharmakumar2011-09-07T13:52:43Z2013-03-05T15:44:38Zhttp://eprints.imtlucca.it/id/eprint/830This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8302011-09-07T13:52:43ZAn intensity based statistical approach for left ventricular localization and identification of end-systolic and end-diastolic images from cine cardiac MRIA critical component in computing quantitative diagnostic metrics, such as ejection fraction, as well as, image segmentation and registration is the accurate identification of the end-systolic (ES) and end-diastolic (ED) frames in cine MRI. Localization of the LV is also
important, to assist further analysis (ie., myocardial segmentation). Currently, these tasks are performed in a manual, semi- or fully-automated fashion. Fully-automated methods are desirable since they can eliminate manual labor and inter- and intra-observer variability. Most methods rely on measuring the area of the blood pool in the LV chamber, but they are computationally intensive,susceptible to noise, and require prior localization and segmentation of the LV. An image-driven statistical method is presented that utilizes cross-correlation (1), to detect ES and ED from cine MRI acquired from canines under control conditions. The purpose of this work is to develop a fully automated, computationally efficient, post-processing method for reliable LV localization and identification of ES and ED frames from cine cardiac MR imagesSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRichard TangRachel KleinRohan Dharmakumar2011-09-07T13:33:50Z2013-03-05T15:44:23Zhttp://eprints.imtlucca.it/id/eprint/828This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8282011-09-07T13:33:50ZAn automated method for left ventricular localization and identification of end-systolic and end-diastolic images from cine cardiac MRIA critical component in computing quantitative diagnostic metrics, such as ejection fraction, as well as image segmentation and registration is the accurate identification of the end-systolic (ES) and end-diastolic (ED) frames in cine MRI. Localization of the LV is also important, to assist further analysis (ie., myocardial segmentation). Currently, these tasks are performed in a manual, semi- or fully-automated fashion. Fully-automated methods are desirable since they can eliminate manual labor and inter- and intra-observer variability. Most methods rely on measuring the area of the blood pool in the LV chamber, but they are computationally intensive, susceptible to noise, and require prior localization and segmentation of the LV. An image-driven statistical method is presented that utilizes cross-correlation to detect ES and ED from cine MRI acquired from canines under control conditions.Sotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itXiangzhi ZhouRichard TangRachel KleinRohan Dharmakumar2011-09-07T13:23:38Z2013-03-05T15:45:03Zhttp://eprints.imtlucca.it/id/eprint/826This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8262011-09-07T13:23:38ZImpact of temporal resolution on cardiac phase-resolved oxygen-sensitive myocardial steady-state free precession imagingCardiac phase-resolved imaging studies that are used in the assessment of cardiac function are performed with a temporal resolution (TRES) of approximately 50 ms to mitigate the effects from cardiac motion and flow. To date, there has been minimal interest on the characterization of myocardial signal intensities from cine images. Steady-state free precession based cardiac phase-resolved blood-oxygen-level-dependent (CP-SSFP BOLD) imaging is a relatively new method for identifying myocardial oxygen abnormalities on the basis of regional signal differences. For reliable assessment of oxygenation changes, it is imperative to ensure that acquisitions enable robust image quality. We hypothesize that TRES plays a significant role on CP-SSFP image quality and that, in particular, myocardial signal characteristics disintegrate with elevations in TRES.Xiangzhi ZhouRichard TangRachel KleinSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itDebiao LiRohan Dharmakumar2011-08-11T11:13:25Z2013-03-05T15:32:50Zhttp://eprints.imtlucca.it/id/eprint/800This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/8002011-08-11T11:13:25ZT2-weighted STIR imaging of myocardial edema associated with ischemia-reperfusion injury: the influence of proton density effect on image contrastTo investigate the contribution of proton density (PD) in T2-STIR based edema imaging in the setting of acute myocardial infarction (AMI). Materials and Methods Canines (n = 5), subjected to full occlusion of the left anterior descending artery for 3 hours, underwent serial magnetic resonance imaging (MRI) studies 2 hours postreperfusion (day 0) and on day 2. During each study, T1 and T2 maps, STIR (TE = 7.1 msec and 64 msec) and late gadolinium enhancement (LGE) images were acquired. Using T1 and T2 maps, relaxation and PD contributions to myocardial edema contrast (EC) in STIR images at both TEs were calculated. Results Edematous territories showed significant increase in PD (20.3 ± 14.3%, P < 0.05) relative to healthy territories. The contributions of T1 changes and T2 or PD changes toward EC were in opposite directions. One-tailed t-test confirmed that the mean T2 and PD-based EC at both TEs were greater than zero. EC from STIR images at TE = 7.1 msec was dominated by PD than T2 effects (94.3 ± 11.3% vs. 17.6 ± 2.5%, P < 0.05), while at TE = 64 msec, T2 effects were significantly greater than PD effects (90.8 ± 20.3% vs. 12.5 ± 11.9%, P < 0.05). The contribution from PD in standard STIR acquisitions (TE = 64 msec) was significantly higher than 0 (P < 0.05). Conclusion In addition to T2-weighting, edema detection in the setting of AMI with T2-weighted STIR imaging has a substantial contribution from PD changes, likely stemming from increased free-water content within the affected tissue. This suggests that imaging approaches that take advantage of both PD as well as T2 effects may provide the optimal sensitivity for detecting myocardial edema. Xiangzhi ZhouVeronica RundellYing LiuRichard TangRachel KleinSaurabh ShahSven ZuehlsdorffSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itDebiao LiRohan Dharmakumar2011-08-11T11:04:04Z2013-03-05T15:34:05Zhttp://eprints.imtlucca.it/id/eprint/799This item is in the repository with the URL: http://eprints.imtlucca.it/id/eprint/7992011-08-11T11:04:04ZArtifact-reduced two-dimensional cine steady state free precession for myocardial blood- oxygen-level-dependent imagingTo minimize image artifacts in long TR cardiac phase-resolved steady state free precession (SSFP) based blood-oxygen-level-dependent (BOLD) imaging.Nine healthy dogs (four male, five female, 20-25 kg) were studied in a clinical 1.5 Tesla MRI scanner to investigate the effect of temporal resolution, readout bandwidth, and motion compensation on long repetition time (TR) SSFP images. Breath-held 2D SSFP cine sequences with various temporal resolutions (10-204 ms), bandwidths (239-930 Hz/pixel), with and without first-order motion compensation were prescribed in the basal, mid-ventricular, and apical along the short axis. Preliminary myocardial BOLD studies in dogs with controllable coronary stenosis were performed to assess the benefits of artifact-reduction strategies.Shortening the readout time by means of increasing readout bandwidth had no observable reduction in image artifacts. However, increasing the temporal resolution in the presence of first-order motion compensation led to significant reduction in image artifacts. Preliminary studies demonstrated that BOLD signal changes can be reliably detected throughout the cardiac cycle.Artifact-reduction methods used in this study provide significant improvement in image quality compared with conventional long TR SSFP BOLD MRI. It is envisioned that the methods proposed here may enable reliable detection of myocardial oxygenation changes throughout the cardiac cycle with long TR SSFP-based myocardial BOLD MRI. Xiangzhi ZhouSotirios A. Tsaftarissotirios.tsaftaris@imtlucca.itYing LiuRichard TangRachel KleinSven ZuehlsdorffDebiao LiRohan Dharmakumar