Archive by Author

Jan201220

1

Simultaneous Right and Left Heart Real-Time, Free-Breathing CMR Flow Quantification Identifies Constrictive Physiology

JACC: Cardiovascular Imaging. 2012; 5(1):15-24

Thavendiranathan P, Verhaert D, Walls MC, Bender JA, Rajagopalan S, Chung Y-C, Simonetti OP, Raman SV

OBJECTIVES: The purpose of this study was to evaluate the ability of a novel cardiac magnetic resonance (CMR) real-time phase contrast (RT-PC) flow measurement technique to reveal the discordant respirophasic changes in mitral and tricuspid valve in flow indicative of the abnormal hemodynamics seen in constrictive pericarditis (CP). Definitive diagnosis of CP requires identification of constrictive hemodynamics with or without pericardial thickening. CMR to date has primarily provided morphological assessment of the pericardium.

METHODS: Sixteen patients (age 57 to 13 years) undergoing CMR to assess known or suspected CP and 10 controls underwent RT-PC that acquired simultaneous mitral valve and tricuspid valve inflow velocities over 10 s of unrestricted breathing. The diagnosis of CP was confirmed via clinical history, diagnostic imaging, cardiac catheterization, intraoperative findings, and histopathology.

RESULTS: Ten patients had CP, all with increased pericardial thickness (6.2 to 1.0 mm). RT-PC imaging demonstrated discordant respirophasic changes in atrioventricular valve inflow velocities in all CP patients, with mean SD mitral valve and tricuspid valve inflow velocity variation of 46 to 20% and 60 to 15%, respectively, compared with 16 to 8% and 24 to 11% in patients without CP (p <0.004 vs. patients with CP for both) and 17 to 5% and 31 to 13% in controls (p < 0.001 vs. patients with CP for both). There was no difference in atrioventricular valve inflow velocity variation between patients without CP compared with controls (p < 0.3 for both). Respiratory variation exceeding 25% across the mitral valve yielded a sensitivity of 100%, a specificity of 100%, and an area under the receiver-operating characteristic curve of 1.0 to detect CP physiology. Using a cutoff of 45%, variation of transtricuspid valve velocity had a sensitivity of 90%, a specificity of 88%, and an area under the receiver-operating characteristic curve of 0.98.

CONCLUSIONS: Accentuated and discordant respirophasic changes in mitral valve and tricuspid valve inflow velocities characteristic of CP can be identified noninvasively with RT-PC CMR. When incorporated into existing CMR protocols for imaging pericardial morphology, RT-PC CMR provides important hemodynamic evidence with which to make a definite diagnosis of CP.

PMID: 22239888

Dec201109

0

3D Echo Systematically Underestimates Right Ventricular Volumes Compared to Cardiovascular Magnetic Resonance in Adult Congenital Heart Disease Patients With Moderate or Severe RV Dilatation

Journal of Cardiovascular Magnetic Resonance. 2011; 13(78):247-251

Andrew M Crean, Neil Maredia, George Ballard, Ravi Menezes, Gill Wharton, Jan Forster, John P Greenwood and John D Thomson

OBJECTIVES: Three dimensional echo is a relatively new technique which may offer a rapid alternative for the examination of the right heart. However its role in patients with non-standard ventricular size or anatomy is unclear. This study compared volumetric measurements of the right ventricle in 25 patients with adult congenital heart disease using both cardiac magnetic resonance (CMR) and three dimensional echocardiography.

METHODS: Patients were grouped by diagnosis into those expected to have normal or near-normal RV size (patients with repaired coarctation of the aorta) and patients expected to have moderate or worse RV enlargement (patients with repaired tetralogy of Fallot or transposition of the great arteries). Right ventricular end diastolic volume, end systolic volume and ejection fraction were compared using both methods with CMR regarded as the reference standard

RESULTS: Bland-Altman analysis of the 25 patients demonstrated that for both RV EDV and RV ESV, there was a significant and systematic under-estimation of volume by 3D echo compared to CMR. This bias led to a mean underestimation of RV EDV by -34% (95%CI: -91% to + 23%). The degree of underestimation was more marked for RV ESV with a bias of -42% (95%CI: -117% to + 32%). There was also a tendency to overestimate RV EF by 3D echo with a bias of approximately 13% (95% CI -52% to +27%).

CONCLUSIONS: Statistically significant and clinically meaningful differences in volumetric measurements were observed between the two techniques. At the current time, three dimensional echocardiography is not interchangeable with CMR for volumetric assessment of ACHD patients who have more than mild RV dilatation.

PMID:

Dec201109

1

Image Quality and Radiation Exposure Using Different Low-Dose Scan Protocols in Dual-Source CT Coronary Angiography: Randomized Study

Radiology. 2011; 261(3):779-786

Lisan A Neefjes, Anoeshka S Dharampal, Alexia Rossi, Koen Nieman, Annick C Weustink, Marcel L Dijkshoorn, Gert-Jan R Ten Kate, Admir Dedic, Stella L Papadopoulou, Marcel van Straten, Filippo Cademartiri, Gabriël P Krestin, Pim J de Feyter, and Nico R Mollet

OBJECTIVES: To compare image quality, radiation dose, and their relationship with heart rate of computed tomographic (CT) coronary angiographic scan protocols by using a 128-section dual-source CT scanner.

METHODS: Institutional review board approved the study; all patients gave informed consent. Two hundred seventy-two patients (175 men, 97 women; mean ages, 58 and 59 years, respectively) referred for CT coronary angiography were categorized according to heart rate: less than 65 beats per minute (group A) and 65 beats per minute or greater (group B). Patients were randomized to undergo prospective high-pitch spiral scanning and narrow-window prospective sequential scanning in group A (n = 160) or wide-window prospective sequential scanning and retrospective spiral scanning in group B (n = 112). Image quality was graded (1 = nondiagnostic; 2 = artifacts present, diagnostic; 3 = no artifacts) and compared (Mann-Whitney and Student t tests).

RESULTS: In group A, mean image quality grade was significantly lower with high-pitch spiral versus sequential scanning (2.67 ± 0.38 [standard deviation] vs 2.86 ± 0.21; P < .001). In a subpopulation (heart rate, <55 beats per minute), mean image quality grade was similar (2.81 ± 0.30 vs 2.94 ± 0.08; P = .35). In group B, image quality grade was comparable between sequential and retrospective spiral scanning (2.81 ± 0.28 vs 2.80 ± 0.38; P = .54). Mean estimated radiation dose was significantly lower (high-pitch spiral vs sequential scanning) in group A (for 100 kV, 0.81 mSv ± 0.30 vs 2.74 mSv ± 1.14 [P < .001]; for 120 kV, 1.65 mSv ± 0.69 vs 4.21 mSv ± 1.20 [P < .001]) and in group B (sequential vs retrospective spiral scanning) (for 100 kV, 4.07 mSv ± 1.07 vs 5.54 mSv ± 1.76 [P = .02]; for 120 kV, 7.50 mSv ± 1.79 vs 9.83 mSv ± 3.49 [P = .1]).

CONCLUSIONS: A high-pitch spiral CT coronary angiographic protocol should be applied in patients with regular and low (<55 beats per minute) heart rates; a sequential protocol is preferred in all others.

PMID: 21969666

Dec201107

0

Exercise-Induced Right Ventricular Dysfunction and Structural Remodelling in Endurance Athletes

European Heart Journal. 2011; 32(23):2911-2918

André La Gerche, Andrew T. Burns, Don J. Mooney, Warrick J. Inder, Andrew J. Taylor, Jan Bogaert, Andrew I. MacIsaac, Hein Heidbüchel and David L. Prior

OBJECTIVES: Endurance training may be associated with arrhythmogenic cardiac remodelling of the right ventricle (RV). We examined whether myocardial dysfunction following intense endurance exercise affects the RV more than the left ventricle (LV) and whether cumulative exposure to endurance competition influences cardiac remodelling (including fibrosis) in well-trained athletes.

METHODS: Forty athletes were studied at baseline, immediately following an endurance race (3–11 h duration) and 1-week post-race. Evaluation included cardiac troponin (cTnI), B-type natriuretic peptide, and echocardiography [including three-dimensional volumes, ejection fraction (EF), and systolic strain rate]. Delayed gadolinium enhancement (DGE) on cardiac magnetic resonance imaging (CMR) was assessed as a marker of myocardial fibrosis.

RESULTS: Relative to baseline, RV volumes increased and all functional measures decreased post-race, whereas LV volumes reduced and function was preserved. B-type natriuretic peptide (13.1 ± 14.0 vs. 25.4 ± 21.4 ng/L, P = 0.003) and cTnI (0.01 ± .03 vs. 0.14 ± .17 μg/L, P < 0.0001) increased post-race and correlated with reductions in RVEF (r = 0.52, P = 0.001 and r = 0.49, P = 0.002, respectively), but not LVEF. Right ventricular ejection fraction decreased with increasing race duration (r = −0.501, P < 0.0001) and VO2max (r = −0.359, P = 0.011). Right ventricular function mostly recovered by 1 week. On CMR, DGE localized to the interventricular septum was identified in 5 of 39 athletes who had greater cumulative exercise exposure and lower RVEF (47.1 ± 5.9 vs. 51.1 ± 3.7%, P = 0.042) than those with normal CMR.

CONCLUSIONS: Intense endurance exercise causes acute dysfunction of the RV, but not the LV. Although short-term recovery appears complete, chronic structural changes and reduced RV function are evident in some of the most practiced athletes, the long-term clinical significance of which warrants further study.

PMID:

Jul201107

1

Acute, Subacute, and Chronic Myocardial Infarction: Quantitative Comparison of 2D and 3D Late Gadolinium Enhancement MR Imaging

Radiology. 2011; 259(3):704-711

Goetti R, Kozerke S, Donati OF, Sürder D, Stolzmann P, Kaufmann PA

OBJECTIVES: To assess a late gadolinium enhancement (LGE) single-breath-hold three-dimensional (3D) inversion recovery magnetic resonance (MR) imaging sequence for the quantification of myocardial scar mass and transmurality in comparison with a clinically established two-dimensional (2D) sequence.

METHODS: All patients gave written informed consent to participate in this institutional review board-approved study. Ninety patients (84 men; mean age, 54.4 years ± 10.8 [standard deviation]) with acute (n = 30), subacute (n = 30), or chronic (n = 30) myocardial infarction were included. Imaging was performed by using a 1.5-T clinical MR imaging system. Spatial resolution was identical for 3D and 2D images (1.5 × 1.5 mm(2); section thickness, 8 mm; no section gap). Quantitative comparisons of myocardial mass (in grams), scar mass (in grams), and scar transmurality (on a five-point scale) were performed by using the Pearson correlation and Bland-Altman analysis (for myocardial and scar mass) or κ statistics (for transmurality).

RESULTS: There were no significant differences between 2D and 3D data sets in terms of mean myocardial mass (2D: 148.3 g ± 35.1; 3D: 148.1 g ± 34.6; P = .76) and scar tissue mass (2D: 31.8 g ± 14.6; 3D: 31.6 g ± 15.5; P = .39), with strong and significant correlation regarding both myocardial mass (r = 0.982; P < .001) and scar tissue mass (r = 0.980; P < .001). Bland-Altman analysis showed a mean difference of 0.21 g ± 6.64 (range, -19.64 to 18.44 g) for myocardial mass and a mean difference of 0.26 g ± 2.88 (range, -7.15 to 7.74 g) for scar mass between the 2D and 3D data sets. Agreement regarding scar transmurality was good (κ = 0.75). Acquisition time was significantly shorter for 3D data sets (26.7 seconds ± 4.4 vs 367.7 seconds ± 56.4; P < .001).

CONCLUSIONS: Three-dimensional LGE MR imaging enables quantitative evaluation of scar tissue mass and transmurality in patients with acute, subacute, or chronic myocardial infarction at significantly reduced acquisition times compared with 2D LGE MR imaging.

PMID: 21467254

Jul201107

1

Cardiovascular MRI for Assessment of Infectious and Inflammatory Conditions of the Heart

American Journal of Roentgenology. 2011; 197(1):103-112

Hoey ET, Gulati GS, Ganeshan A, Watkin RW, Simpson H, Sharma S

OBJECTIVES: This article reviews the role of cardiovascular MRI in the diagnosis and characterization of the spectrum of infectious and inflammatory disorders of the heart. An imaging protocol is described, and typical MRI findings are discussed and illustrated.

CONCLUSIONS: Radiologists should be aware of the spectrum of infectious and inflammatory conditions that can affect the heart and the role of MRI in conjunction with other imaging techniques in their assessment.

PMID: 21701017

Feb201119

4

T2-Weighted Cardiovascular Magnetic Resonance in Acute Cardiac Disease

Journal of Cardiovascular Magnetic Resonance. 2011; 13(13):324

Friedrich MG, Eitel I

Cardiovascular magnetic resonance (CMR) using T2-weighted sequences can visualize myocardial edema. When compared to previous protocols, newer pulse sequences with substantially improved image quality have increased its clinical utility. The assessment of myocardial edema provides useful incremental diagnostic and prognostic information in a variety of clinical settings associated with acute myocardial injury. In patients with acute chest pain, T2-weighted CMR is able to identify acute or recent myocardial ischemic injury and has been employed to distinguish acute coronary syndrome (ACS) from non-ACS as well as acute from chronic myocardial infarction. T2-weighted CMR can also be used to determine the area at risk in reperfused and non-reperfused infarction. When combined with contrast-enhanced imaging, the salvaged area and thus the success of early coronary revascularization can be quantified. Strong evidence for the prognostic value of myocardial salvage has enabled its use as a primary endpoint in clinical trials. The present article reviews the current evidence and clinical applications for T2-weighted CMR in acute cardiac disease and gives an outlook on future developments. “The principle of all things is water” Thales of Miletus (624 BC – 546 BC)

PMID:

Dec201014

3

Shortened Modified Look-Locker Inversion Recovery (ShMOLLI) for Clinical Myocardial T1-Mapping at 1.5 and 3 T Within A 9 Heartbeat Breathhold

J Cardiovasc Magn Reson. 2010; 12(1):69-80

Piechnik SK, Ferreira VM, Dall'armellina E, Cochlin LE, Greiser A, Neubauer S, Robson MD

OBJECTIVES: T1 mapping allows direct in-vivo quantitation of microscopic changes in the myocardium, providing new diagnostic insights into cardiac disease. Existing methods require long breath holds that are demanding for many cardiac patients. In this work we propose and validate a novel, clinically applicable, pulse sequence for myocardial T1-mapping that is compatible with typical limits for end-expiration breath-holding in patients.

METHODS: The Shortened MOdified Look-Locker Inversion recovery (ShMOLLI) method uses sequential inversion recovery measurements within a single short breath-hold. Full recovery of the longitudinal magnetisation between sequential inversion pulses is not achieved, but conditional interpretation of samples for reconstruction of T1-maps is used to yield accurate measurements, and this algorithm is implemented directly on the scanner. We performed computer simulations for 100ms<T1<2.7s and heart rates 40-100bpm followed by phantom validation at 1.5T and 3T. In-vivo myocardial T1-mapping using this method and the previous gold-standard (MOLLI) was performed in 10 healthy volunteers at 1.5T and 3T, 4 volunteers with contrast injection at 1.5T, and 4 patients with recent myocardial infarction (MI) at 3T.

RESULTS: We found good agreement between the average ShMOLLI and MOLLI estimates for T1<1200ms. In contrast to the original method, ShMOLLI showed no dependence on heart rates for long T1 values, with estimates characterized by a constant 4% underestimation for T1=800-2700ms. In-vivo, ShMOLLI measurements required 9.0+/-1.1s (MOLLI=17.6+/-2.9s). Average healthy myocardial T1s by ShMOLLI at 1.5T were 966+/-48ms (mean+/-SD) and 1166+/-60ms at 3T. In MI patients, the T1 in unaffected myocardium (1216+/-42ms) was similar to controls at 3T. Ischemically injured myocardium showed increased T1=1432+/-33ms (p<0.001). The difference between MI and remote myocardium was estimated 15% larger by ShMOLLI than MOLLI (p<0.04) which suffers from heart rate dependencies for long T1. The in-vivo variability within ShMOLLI T1-maps was only 14% (1.5T) or 18% (3T) higher than the MOLLI maps, but the MOLLI acquisitions were twice longer than ShMOLLI acquisitions.

CONCLUSIONS: ShMOLLI is an efficient method that generates immediate, high-resolution myocardial T1-maps in a short breath-hold with high precision. This technique provides a valuable clinically applicable tool for myocardial tissue characterisation.

PMID: 21092095