Steve W Leung

Dr. Steve W Leung

orcid

Research Focus & Metrics

Academic Career Length

15Years (2012-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 January 2015 in Journal of Cardiovascular Magnetic Resonance
Verified
Journal Article
Open access
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TSTori A. Stromp
Tori A. Stromp
SLSteve W Leung
Steve W Leung
KAKristin N. Andres
Kristin N. Andres
LJLinyuan Jing
Linyuan Jing
BFBrandon K. Fornwalt
Brandon K. Fornwalt
MVMoriel H. Vandsburger
Moriel H. Vandsburger
Cardiovascular magnetic resonance (CMR) of ventricular structure and function is widely performed using cine balanced steady state free precession (bSSFP) MRI. The bSSFP signal of myocardium is weighted by magnetization transfer (MT) and T1/T2-relaxation times. In edematous and fibrotic tissues, increased T2 and reduced MT lead to increased signal intensity on images acquired with high excitation flip angles. We hypothesized that acquisition of two differentially MT-weighted bSSFP images (termed 2-point bSSFP) can identify tissue that would enhance with gadolinium similar to standard of care late gadolinium enhancement (LGE). Cine bSSFP images (flip angles of 5° and 45°) and native-T1 and T2 maps were acquired in one mid-ventricular slice in 47 patients referred for CMR and 10 healthy controls. Afterwards, LGE images and post-contrast T1 maps were acquired and gadolinium partition coefficient (GPC) was calculated. Maps of ΔS/So were calculated as (S45-S5)/S5*100 (%), where Sflip_angle is the voxel signal intensity. Twenty three patients demonstrated areas of myocardial hyper-enhancement with LGE. In enhanced regions, ΔS/So, native-T1, T2, and GPC were heightened (p < 0.05 vs. non-enhanced tissues). ΔS/So, native-T1, and T2 all demonstrated association with GPC, however the association was strongest for ΔS/So. Bland-Altman analysis revealed a slight bias towards larger volume of enhancement with ΔS/So compared to LGE, and similar transmurality. Subjective analysis with 2-blinded expert readers revealed agreement between ΔS/So and LGE of 73.4 %, with false positive detection of 16.7 % and false negative detection of 15.2 %. Gadolinium free 2-point bSSFP identified tissue that enhances at LGE with strong association to GPC. Our results suggest that with further development, MT-weighted CMR could be used similar to LGE for diagnostic imaging.

27 April 2021 in Infectious Diseases
Verified
Journal Article
Closed access
GSGregory J. Sinner
Gregory J. Sinner
RARahul Annabathula
Rahul Annabathula
KVKarolina Viquez
Karolina Viquez
TATalal S. Alnabelsi
Talal S. Alnabelsi
SLSteve W Leung
Steve W Leung
Endocarditis during pregnancy carries a maternal mortality of up to 30%, but prior publications do not reflect the current opioid epidemic.We reviewed our institution’s infective endocarditis regis...

15 May 2019 in NMR in Biomedicine
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Journal Article
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WAWissam AlGhuraibawi
Wissam AlGhuraibawi
TSTori Stromp
Tori Stromp
RHRebecca Holtkamp
Rebecca Holtkamp
BLBonnie Lam
Bonnie Lam
WRWolfgang Rehwald
Wolfgang Rehwald
MVMoriel Vandsburger
Moriel Vandsburger
Systolic cardiac function is typically preserved in obese adults, potentially masking underlying declines in cardiomyocyte metabolism that may contribute to heart failure. We used chemical exchange saturation transfer (CEST) MRI, a sensitive method for measurement of myocardial creatine, to examine whether myocardial creatine levels correlate with cardiac structure, contractile function, or visceral fat mass in obese adults. In this study, obese (body mass index, BMI > 30, n = 20) and healthy (BMI < 25, n = 11) adults were examined with dual‐energy x‐ray absorptiometry to quantify fat masses. Cine MRI and myocardial tagging were performed at 1.5 T to measure ventricular structure and global function. CEST imaging with offsets in the range of ±10 parts per million (ppm) were performed in one mid‐ventricular slice, where creatine CEST contrast was calculated at 1.8 ppm following field homogeneity correction. Ventricular structure, global function (ejection fraction 69.4 ± 4.3% healthy versus 69.6 ± 9.3% obese, NS), and circumferential strain (−17.0 ± 2.3% healthy versus −16.5 ± 1.5% obese, NS) and strain rate were preserved in obese adults. However, creatine CEST contrast was significantly reduced in obese adults (6.8 ± 1.3% healthy versus 4.1 ± 2.7% obese, p = 0.001). Creatine CEST contrast was inversely correlated with total body fat% (ρ = −0.45, p = 0.011), visceral fat mass (ρ = −0.58, p = 0.001), and septal wall thickness (ρ = −0.44, p = 0.013), but uncorrelated to ventricular function or contractile function. In conclusion, creatine CEST‐MRI reveals a strong correlation between heightened body and visceral fat masses and reduced myocardial metabolic function that is independent of ventricular structure and global function in obese adults.

7 February 2023 in EP Europace
Verified
Journal Article
Open access
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YDYousef Darrat
Yousef Darrat
SLSteve W Leung
Steve W Leung
LELiliane Elayi
Liliane Elayi
KPKevin Parrott
Kevin Parrott
GOGbolahan Ogunbayo
Gbolahan Ogunbayo
CEClaude S Elayi
Claude S Elayi
Cardioversion is a very commonly performed procedure for persistent atrial fibrillation (AF). However, there is no well-defined protocol to address failed external electrical direct current cardioversion. The aim of the study is to test the efficacy of a pre-defined stepwise cardioversion protocol for patients with persistent AF of ≤12 months. Success was the achievement of sinus rhythm. The study population included patients with persistent AF of ≤12 months duration requiring rhythm management. Patients were offered cardioversion using a pre-defined stepwise protocol using different electrode placement locations, applying compression at end of expiration, and higher energy delivered simultaneously through two defibrillators. : A total of 414 patients were included in the study, of which 362 (87.4%) required a single successful cardioversion. The remaining 52 (12.5%) patients required additional cardioversion attempts using the stepwise cardioversion protocol with an overall success rate of 99.3%. Two simultaneous defibrillators were required in 14 patients (3.4%). Patients with multiple cardioversions (13.5%) experienced more local skin irritation and pain compared with patients with single cardioversion (13.5% vs. 3.5%, P = 0.004). The predictor for the need for multiple cardioversion attempts is high body mass index, while high transthoracic impedance is associated with failed cardioversion. No major complications were observed during the study. The stepwise cardioversion protocol has a high success rate of >99% and can be safely performed in outpatient or inpatient settings.

19 November 2018 in Scientific Reports
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Journal Article
Open access
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TSTori A. Stromp
Tori A. Stromp
TSTyler J. Spear
Tyler J. Spear
RHRebecca M. Holtkamp
Rebecca M. Holtkamp
KAKristin N. Andres
Kristin N. Andres
JKJoshua C. Kaine
Joshua C. Kaine
MVMoriel H. Vandsburger
Moriel H. Vandsburger
Patients with end stage renal disease (ESRD) suffer high mortality from arrhythmias linked to fibrosis, but are contraindicated to late gadolinium enhancement magnetic resonance imaging (MRI). We present a quantitative method for gadolinium-free cardiac fibrosis imaging using magnetization transfer (MT) weighted MRI, and probe correlations with widely used surrogate markers including cardiac structure and contractile function in patients with ESRD. In a sub-group of patients who returned for follow-up imaging after one year, we examine the correlation between changes in fibrosis and ventricular structure/function. Quantification of changes in MT revealed significantly greater fibrotic burden in patients with ESRD compared to a healthy age matched control cohort. Ventricular mechanics, including circumferential strain and diastolic strain rate were unchanged in patients with ESRD. No correlation was observed between fibrotic burden and concomitant measures of either circumferential or longitudinal strains or strain rates. However, among patients who returned for follow up examination a strong correlation existed between initial fibrotic burden and subsequent loss of contractile function. Gadolinium-free myocardial fibrosis imaging in patients with ESRD revealed a complex and longitudinal, not contemporary, association between fibrosis and ventricular contractile function.

1 April 2018 in Journal of Critical Care
Verified
Journal Article
Closed access
VGVedant Gupta
Vedant Gupta
MSMatthew Sousa
Matthew Sousa
NKNathan Kraitman
Nathan Kraitman
RARahul Annabathula
Rahul Annabathula
OVOlga Vsevolozhskaya
Olga Vsevolozhskaya
VSVincent L. Sorrell
Vincent L. Sorrell