Myocardium at Risk After Acute Infarction in Humans on Cardiac Magnetic Resonance
Quantitative Assessment During Follow-Up and Validation With Single-Photon Emission Computed Tomography

Marcus Carlsson, MD, PhD*, Joey F.A. Ubachs, MD*, Erik Hedström, MD, PhD*, Einar Heiberg, PhD*, Stefan Jovinge, MD, PhD, Håkan Arheden, MD, PhD*,*

* Cardiac MR Group, Department of Clinical Physiology, Lund University Hospital, Lund, SwedenDepartment of Cardiology, Lund University Hospital, Lund, Sweden

Objectives: Our goal was to validate myocardium at risk on T2-weighted short tau inversion recovery (T2-STIR) cardiac magnetic resonance (CMR) over time, compared with that seen with perfusion single-photon emission computed tomography (SPECT) in patients with ST-segment elevation myocardial infarction, and to assess the amount of salvaged myocardium after 1 week.

Background: To assess reperfusion therapy, it is necessary to determine how much myocardium is salvaged by measuring the final infarct size in relation to the initial myocardium at risk of the left ventricle (LV).

Methods: Sixteen patients with first-time ST-segment elevation myocardial infarction received 99mTc tetrofosmin before primary percutaneous coronary intervention. SPECT was performed within 4 h and T2-STIR CMR within 1 day, 1 week, 6 weeks, and 6 months. At 1 week, patients were injected with a gadolinium-based contrast agent for quantification of infarct size.

Results: Myocardium at risk at occlusion on SPECT was 33 ± 10% of the LV. Myocardium at risk on T2-STIR did not differ from SPECT, at day 1 (29 ± 7%, p = 0.49) or week 1 (31 ± 6%, p = 0.16) but declined at week 6 (10 ± 12%, p = 0.0096 vs. 1 week) and month 6 (4 ± 11%, p = 0.0013 vs. 1 week). There was a correlation between myocardium at risk demonstrated by T2-STIR at week 1 and myocardium at risk by SPECT (r2 = 0.70, p < p =" 0.16).">

Conclusions: This study demonstrates that T2-STIR performed up to 1 week after reperfusion can accurately determine myocardium at risk as it was before opening of the occluded artery. CMR can also quantify salvaged myocardium as myocardium at risk minus final infarct size.

Key Words: myocardium at risk • T2-STIR • CMR • salvaged myocardium

Am Coll Cardiol Img, 2009; 2:569-576

Association of Thrombolysis in Myocardial Infarction Myocardial Perfusion Grade with cardiovascular magnetic resonance measures of infarct architecture after primary percutaneous coronary intervention for ST-segment elevation myocardial infarction.

Appelbaum E, Abraham JM, Pride YB, Harrigan CJ, Peters DC, Biller LH, Manning WJ, Gibson CM.

Division of Cardiovascular Medicine, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.

BACKGROUND: Primary percutaneous coronary intervention (pPCI) routinely restores normal epicardial flow among patients with ST-segment elevation myocardial infarction (STEMI). However, impairment of myocardial perfusion frequently persists. The goal of this analysis was to determine whether impaired myocardial perfusion was associated with cardiovascular magnetic resonance-defined abnormalities in infarct architecture, including infarct size (IS), infarct surface area (ISA), infarct border zone (IBZ), and infarct complexity (IC).

METHODS: Thirty-one patients with STEMI treated with pPCI were included in the analysis. Cardiovascular magnetic resonance was performed within 7 days of presentation and repeated at 3 months. Infarct complexity was defined as the ratio of actual ISA to an idealized smooth ISA and normalized to IS.

RESULTS: Impaired Thrombolysis in Myocardial Infarction Myocardial Perfusion Grade (TMPG) (<3) was associated with larger ISA at baseline (78.2 +/- 25.3 cm(2) vs 40.3 +/- 30.3 cm(2), P = .02) and follow-up (58.8 +/- 27.5 cm(2) vs 26.3 +/- 20.2 cm(2), P = .03) and larger IBZ at follow-up (7.8% +/- 2.7% vs 4.1% +/- 3.3%, P = .02). At follow-up, ISA, when normalized to IS, was significantly higher among patients with impaired myocardial perfusion (TMPG <3) (6.9 +/- 2.5 vs 5.9 +/- 2.4 cm(2)/%, P = .03). Thrombolysis in MI myocardial perfusion grade <3 was also associated with increased IC at follow-up (52% +/- 12% vs 33% +/- 16%, P = .01).">

CONCLUSIONS: Impaired TMPG is associated with larger ISA, IBZ, and increased IC. At 3 months, TMPG remained associated with ISA and IC after adjusting for IS, suggesting that impaired TMPG after pPCI is associated with infarct architecture after healing, independent of IS.

Am Heart J. 2009 Jul;158(1):84-91.

Prognosis Information is key in CMR

Prognostic information has always been a field publicized by nuclear medicine colleagues. However, CMR has gained such an advantage in this area with MDE and such that it is now one of the most powerful tools to assess in what direction a patient is going. A comprehensive review on the topic can be read below:

http://circimaging.ahajournals.org/cgi/content/extract/2/3/243

Juliano

MDE: 2D and 3D GRE

2D IR-GRE is still the leading pulse sequence used by most visitors. However, 3D is not too closely behind it. With higher resolution images and 3T, one breath-hold whole heart coverage can be obtained quite easily with 3D despite the slightly increased noise.

Seeing is believing

ATVB has put up a series of Brief Reviews on Atherosclerosis Imaging, with many topics on CMR. I personally believe that these new markers/technologies will perpetuate CMR for years to come. Check each article below or click on the ATVB site:

http://atvb.ahajournals.org/content/vol29/issue7/?etoc

Brief Reviews
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Cardiovascular Molecular Imaging
Zahi A. Fayad
Arterioscler Thromb Vasc Biol 2009;29:981-982
http://atvb.ahajournals.org/cgi/content/extract/29/7/981?etoc


Molecular Imaging in Atherosclerosis, Thrombosis, and Vascular Inflammation
Robin P. Choudhury and Edward A. Fisher
Arterioscler Thromb Vasc Biol 2009;29:983-991
http://atvb.ahajournals.org/cgi/content/abstract/29/7/983?etoc


Nanotechnology in Medical Imaging: Probe Design and Applications
David P. Cormode, Torjus Skajaa, Zahi A. Fayad, and Willem J.M. Mulder
Arterioscler Thromb Vasc Biol 2009;29:992-1000
http://atvb.ahajournals.org/cgi/content/abstract/29/7/992?etoc
Nanoparticles are a crucial part of the next generation of contrast agents
for medical imaging. Herein we discuss the different aspects of
nanoparticle probe design and highlight some of the most advanced examples.



Iron Oxide Particles for Atheroma Imaging
Tjun Y. Tang, Karin H. Muller, Martin J. Graves, Zhi Y. Li, Stewart R.
Walsh, Victoria Young, Umar Sadat, Simon P.S. Howarth, and J.H. Gillard
Arterioscler Thromb Vasc Biol 2009;29:1001-1008
http://atvb.ahajournals.org/cgi/content/abstract/29/7/1001?etoc


Inflammation Imaging in Atherosclerosis
James H.F. Rudd, Fabien Hyafil, and Zahi A. Fayad
Arterioscler Thromb Vasc Biol 2009;29:1009-1016
http://atvb.ahajournals.org/cgi/content/abstract/29/7/1009?etoc


Optical and Multimodality Molecular Imaging: Insights Into Atherosclerosis
Farouc A. Jaffer, Peter Libby, and Ralph Weissleder
Arterioscler Thromb Vasc Biol 2009;29:1017-1024
http://atvb.ahajournals.org/cgi/content/abstract/29/7/1017?etoc


In Vivo Imaging of Stem Cells and Beta Cells Using Direct Cell Labeling and
Reporter Gene Methods
Dara L. Kraitchman and Jeff W.M. Bulte
Arterioscler Thromb Vasc Biol 2009;29:1025-1030
http://atvb.ahajournals.org/cgi/content/abstract/29/7/1025?etoc
Cellular transplantation offers a means to stimulate cardiovascular repair.
Cell labeling with contrast agents or transfection with reporter genes have
enabled serial dynamic imaging of cell survival, fate, and engraftment. In
this review article, we explore some of the state-of-the art methods for
stem, progenitor, and beta cell tracking.




Molecular Imaging of Macrophage Cell Death for the Assessment of Plaque
Vulnerability
Eduard M. Laufer, Mark H.M. Winkens, Jagat Narula, and Leonard Hofstra
Arterioscler Thromb Vasc Biol 2009;29:1031-1038
http://atvb.ahajournals.org/cgi/content/abstract/29/7/1031?etoc

Validation of cardiovascular magnetic resonance assessment of
pericardial adipose tissue volume.

Adam J Nelson, Matthew I Worthley, Peter J Psaltis, Angelo Carbone,
Benjamin K Dundon, Rae F Duncan, Cynthia Piantadosi, Dennis H Lau,
Prashanthan Sanders, Gary A Wittert and Stephen G Worthley*

Abstract
Background: Pericardial adipose tissue (PAT) has been shown to be an independent predictor of coronary artery disease. To date its assessment has been restricted to the use of surrogate
echocardiographic indices such as measurement of epicardial fat thickness over the right ventricular freewall, which have limitations. Cardiovascular magnetic resonance (CMR) offers the potential to noninvasively total PAT, however like other imaging modalities, CMR has not yet been validated for this purpose. Thus, we sought to describe a novel technique for assessing total PAT with validation in an ovine model.
Methods: 11 merino sheep were studied. A standard clinical series of ventricular short axis CMR images (1.5T Siemens Sonata) were obtained during mechanical ventilation breath-holds. Beginning at the mitral annulus, consecutive end-diastolic ventricular images were used to determine the area and volume of epicardial, paracardial and pericardial adipose tissue. In addition adipose thickness was measured at the right ventricular free wall. Following euthanasia, the paracardial adipose tissue was removed from the ventricle and weighed to allow comparison with corresponding CMR measurements.
Results: There was a strong correlation between CMR-derived paracardial adipose tissue volume and ex vivo paracardial mass (R2 = 0.89, p < 0.001). In contrast, CMR measurements of corresponding RV free wall paracardial adipose thickness did not correlate with ex vivo paracardial mass (R2 = 0.003, p = 0.878).
Conclusion: In this ovine model, CMR-derived paracardial adipose tissue volume, but not the
corresponding and conventional measure of paracardial adipose thickness over the RV free wall, accurately reflected paracardial adipose tissue mass. This study validates for the first time, the use of clinically utilised CMR sequences for the accurate and reproducible assessment of pericardial adiposity. Furthermore this non-invasive modality does not use ionising radiation and therefore is ideally suited for future studies of PAT and its role in cardiovascular risk prediction and disease in clinical practice.

Journal of Cardiovascular Magnetic Resonance 2009, 11:15

Dobutamine Cardiac Magnetic Resonance Results Predict Cardiac Prognosis in Women With Known or Suspected Ischemic Heart Disease.

Eric L. Wallace, DO*, Timothy M. Morgan, PhD, Thomas F. Walsh, MD*, Erica Dall'Armellina, MD*, William Ntim, MD, FACC*, Craig A. Hamilton, PhD, W. Gregory Hundley, MD, FACC*,,*

Objectives: The purpose of this study was to determine the prognostic utility of dobutamine cardiac magnetic resonance (DCMR) stress test results in women.
Background: To date, the preponderance of studies reporting the utility of DCMR stress results for predicting cardiac prognosis have been performed in men. We sought to determine the utility of DCMR results for predicting cardiac prognosis in women.
Methods: Two hundred sixty-six consecutively referred women underwent DCMR in which left ventricular wall motion (LVWM) was assessed at rest and after intravenous dobutamine and atropine. Inducible LVWM abnormalities were identified during testing. Women were contacted to determine the post-DCMR occurrence of a cardiac event. All events were substantiated according to defined criteria and then were verified after a thorough medical record review by individuals blinded to testing data.
Results: Women were contacted an average of 6.2 ± 1.6 (median 6.2, range 0.8 to 10.4) years after DCMR; 27% of the women experienced an inducible LVWM abnormality during testing. In those with and without inducible LVWM abnormalities, the proportion of women with cardiac events were 63% versus 30%, respectively, (hazard ratio [HR]: 2.7; 95% confidence interval [CI]: 1.8 to 4.3 for the presence of inducible LVWM abnormalities p < 0.0001). The proportion of women with myocardial infarction (MI) and cardiac death were 33.3% and 7.5%, respectively. This resulted in a HR for MI and cardiac death of 4.1 (95% CI: 2.2 to 9.4) for those with versus those without inducible LVWM abnormalities; p < 0.0001. A subgroup analysis was performed in women without a history of coronary artery disease and in those with LVWM abnormalities, DCMR remained an adverse predictor of cardiac events (HR: 4.0, 95% CI: 1.8 to 9.0, p = 0.003).
Conclusions: Inducible LVWM abnormalities during DCMR predict cardiac death and MI in women. Similar to men, these results indicate that DCMR is a valuable noninvasive stress imaging modality for identifying cardiac risk in women with known or suspected ischemic heart disease.

J Am Coll Cardiol Img, 2009; 2:299-307

2010 Abstract Submission Site Open

The 2010 SCMR Abstract Submission Site is now open.

Deadline is September 15.

Send your abstracts through the OASIS site:

CLICK HERE TO ENTER THE SITE


Juliano

How to perform Quantification of Absolute Myocardial Blood Flow by Magnetic Resonance Perfusion Imaging?

A state-of-the-art paper was just released in Jacc Imaging detailing how to apply these measurements both in daily use as well as in research.

Read the abstract here.

Juliano

Myocardial Hypertrophy, ECG and CMR

What is the best way to asses LV hypertrophy by ECG? The answer, according to CMR, is by using the Romhilt-Estes score. The full paper is accessible in JCMR for free:


Electrocardiographic diagnosis of left ventricular hypertrophy in aortic valve disease: evaluation of ECG criteria by cardiovascular magnetic resonance
Buchner S, Debl K, Haimerl J, Djavidani B, Poschenrieder F, Feuerbach S, Riegger GA, Luchner A
Journal of Cardiovascular Magnetic Resonance 2009, 11:18 (1 June 2009)

READ THE FULL PDF HERE

Miocardio No Compactado

Sin duda alguna estamos ante un caso de Miocardio No Compactado, que no se está presentando de forma inicial con toda la triada clásica descrita por Chin TK et al, en 1990 en su publicación en la revista Circulation que dice: La tríada está compuesta por insuficiencia cardíaca, arritmias y eventos cardioembólicos que es la principal manifestación observada, tanto en población pediátrica como en adultos con deterioro de la función sistólica del VI. Pueden observarse diferentes arritmias, desde una fibrilación auricular hasta una taquicardia ventricular sostenida. Ahora por qué estamos ante un caso de MNC? Lo primero que hay que plantearse son los diagnósticos diferenciales para poder llegar a la conclusión. La diferenciación entre MNC y otras entidades que afectan al VI puede ser dificultosa. Sin embargo Frischknecht BS et al, realizó un estudio ciego, reviendo estudios ecocardiográficos grabado en cintas de vídeo a los cuales se les aplicaron los criterios establecidos para el diagnóstico de MNC con la finalidad de diferenciar esta entidad de otras tales como MCD, miocardiopatía hipertensiva, cardiopatías valvulares y presencia de trabeculaciones y bandas aberrantes. La diferenciación entre MNC, MCH y miocardiopatia hipertensiva deben ser los diagnósticos diferenciales más importantes que debemos platearnos. Por eso la importancia de que Frischknecht BS et al describieran claramente en sus trabajos de investigación que la estructura clásica de dos capas miocárdicas del MNC, no es patrimonio exclusivo de éste, dicha estructura estuvo presente casi en el 26% de los pacientes con MCD y MCH pero no se mantenía una relación >2 entre las porciones no compactada/compactada como se observa claramente en este paciente. Además en pacientes con miocardiopatías valvulares, también está presente la estructura en dos capas ya descrita, pero las regiones engrosadas se encuentran presente incluso en el septum interventricular, lo cual es completamente diferente a la hallado en el MNC, donde sólo los segmentos afectados se encuentran engrosados y donde el septum es, por lo general, respetado criterio que muestra este paciente. El espesor del septum interventricular es importante a la hora de realizar el diagnóstico diferencial, ya que en el MNC se encuentra respetado casi en la totalidad de los casos, lo cual no ocurre en miocardiopatías valvulares.
Ahora, por otra parte vale la pena mencionar que no existe un VI aparentemente dilatado como se observa en este caso, con esa relación de compactación y no compactación que pueda ser una variante normal de un individuo sano. Por eso creo oportuno también recordar un poco sobre otras características de las cámaras cardiacas como la presencia de bandas aberrantes en corazones normales que no es un hallazgo infrecuente (0,5 al 50%) y que si constituye una variante normal de algunos individuos. En conclusión acerca de la diferenciación de esta entidad, se puede asumir que algunos criterios diagnósticos de MNC pueden estar presentes en otras patologías, pero la combinación de todos ellos es de alta especificidad. En pacientes sin evidencia de enfermedades neuromusculares, la presencia de hipertrabeculación no es un criterio suficientemente sensible. La posibilidad de encontrar la totalidad de los criterios para MNC en otra patología es ≤ 5%.

Dra Florangel Martínez. Centro Clínico Valentina Canabal. Barquisimeto-Venezuela.