Cardiac CT & MRI Literature

Improvement in wall motion in a 50% infarct after revascularization

This 46-years old man came with an acute LAD territory infarct involving the anterior wall and septum. Most of the infarct involved approx. 50-60% of the thickness of the myocardium (Figs. 1-3 - pre). A tight proximal LAD lesion was seen on angiography, which was stented. Five months later, the patient presented for a follow-up study, which showed mild retraction of the infarct and an approx. 40-50% involvement of the thickness of the myocardium (FIgs. 2, 3 - post).

More importantly, the severe hypokinesia in the anterior and antero-septal walls had virtually completely regressed (cine files), suggesting response to revascularization.

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Magnetic Resonance Assessment of the Substrate for Inducible Ventricular Tachycardia in Nonischemic Cardiomyopathy -- Nazarian et al. 112 (18): 2821 -- Circulation

This article by Nazarian et al in this week's issue of Circulation shows that scar diagnosed on contrast-enhanced CMR is significantly predictive of inducible ventricular tachycardia, even after adjusting for LV ejection fraction.

Scar involving 26-75% of the myocardium was predictive and can identify high-risk individuals.

Link: Magnetic Resonance Assessment of the Substrate for Inducible Ventricular Tachycardia in Nonischemic Cardiomyopathy -- Nazarian et al. 112 (18): 2821 -- Circulation.

A case highlighting this issue has been published in our accompanying images blog.

Differentiating Acute Myocardial Infarction from Myocarditis: Diagnostic Value of Early- and Delayed-Perfusion Cardiac MR Imaging -- Laissy et al. 237 (1): 75 -- Radiology

This article describes the difference between the enhancement patterns in acute myocarditis and infarction. The differentiation is pretty straightforward. Infarcts show a defect on first-pass imaging, with a subendocardial-transmural enhancement corresponding to an infarct territory. Myocarditis shows no change on first pass imaging with mid-myocardial to epicardial, patchy areas of enhancement.

This is also illustrated in the accompanying images blog in the entry of Tuesday, 01 Nov.

Link: Differentiating Acute Myocardial Infarction from Myocarditis: Diagnostic Value of Early- and Delayed-Perfusion Cardiac MR Imaging -- Laissy et al. 237 (1): 75 -- Radiology.

Double aortic arch and tracheal compression

This is an article by Chan MSM et al from Hong Kong, in this month's AJR, that shows how with a single dataset, we can get exquisite angiogram and tracheo-bronchial tree images of a double aortic arch patient. When the patient is under anesthesia, "inspiratory expiratory" images can be obtained to look for concomitant tracheomalacia.

We recently saw a similar patient, where however the tracheal compression was mild to moderate. We could not however perform a dynamic study for tracheomalacia, since all our parients are scanned under deep sedation only.

Limited diagnostic yield of non-invasive coronary angiography by 16-slice multi-detector spiral computed tomography in routine patients referred for evaluation of coronary artery disease -- Kaiser et al. 26 (19): 1987 -- European Heart Journal

This article from Switzerland is one of the first that shows poor results with 16-slice CT, in unselected patients..

The results shown in this article, in 149 consecutive patients, are really dismal with an overall sensitivity of picking up significant CAD of 86%, but a specificity of just 49%. On a per segment basis, the sensitivity was just 30%.

This article obviously needs to be read in more detail. What is seen, is that the patients were truly unselected no calcium scoring was performed before the procedure. No attempt was also made to control the heart rate and though not statistically significant, those with higher heart rates had poorer results.

The biggest problem according to the authors was calcification, which both masked and simulated disease, where it was present. A similar article by Achenbach's group last year in a smaller series of 33 patients, came to almost similar conclusions.

This is of interest because there is now a trend with 64-slice CTs, to disregard the presence of calcification and to proceed with CT angiography. As the cases (case 1, case 2, case 3, case 4) in the accompanying images blog show, as long as there is no calcification and the attention to technique is properly maintained, the results are excellent. But the moment there is calcification, things really start going wrong and we now report often that "dense calcification is seen preventing adequate lumen visualization". In my opinion, it is often easier to common on in-stent restenosis, than to see the lumen through dense calcium.

Link: Limited diagnostic yield of non-invasive coronary angiography by 16-slice multi-detector spiral computed tomography in routine patients referred for evaluation of coronary artery disease -- Kaiser et al. 26 (19): 1987 -- European Heart Journal.

Dynamic Cine Imaging of the Mitral Valve with 16-MDCT: A Feasibility Study -- Alkadhi et al. 185 (3): 636 -- American Journal of Roentgenology

This is a nice proof-of-concept article on the use of CT in mitral valvular imaging. The techniques and anatomy have been well explained and it is obvious that with the newer 64-slice scanners, it will be much easier to perform these reconstructions.

Link: Dynamic Cine Imaging of the Mitral Valve with 16-MDCT: A Feasibility Study -- Alkadhi et al. 185 (3): 636 -- American Journal of Roentgenology.

Myocardial Infarct: Depiction with Contrast-enhanced MR Imaging--Comparison of Gadopentetate and Gadobenate -- Schlosser et al. 236 (3): 1041 -- Radiology

This is a very interesting article that compares Multihance and Magnevist and makes a case to not switch to Multihance due to the prolonged intracavitary blood-pool enhancement, which makes depiction of subendocardial infarcts difficult and prolongs examination times.

Link: Myocardial Infarct: Depiction with Contrast-enhanced MR Imaging--Comparison of Gadopentetate and Gadobenate -- Schlosser et al. 236 (3): 1041 -- Radiology.

Enhanced Coronary Calcification Determined by Electron Beam CT Is Strongly Related to Endothelial Dysfunction in Patients With Suspected Coronary Artery Disease -- Huang et al. 128 (2): 810 -- Chest

This article furthers the argument that high coronary artery calcium scores are associated not only with enhanced plaque burden, but also endothelial dysfunction

Link: Enhanced Coronary Calcification Determined by Electron Beam CT Is Strongly Related to Endothelial Dysfunction in Patients With Suspected Coronary Artery Disease -- Huang et al. 128 (2): 810 -- Chest.

Utility of Cardiac Magnetic Resonance Imaging in the Diagnosis of Hypertrophic Cardiomyopathy -- Rickers et al. 112 (6): 855 -- Circulation

This article in the current issue of Circulation again reiterates what is now a known fact. CMR is a superior tool to echocardiography as far as evaluation of HCM is concerned. This article does not assess the importance of delayed hyperenhancement, which over and above the superior assessment of the cine images, provides additional information, which may eventually carry significant prognostic value as well.

Link: Utility of Cardiac Magnetic Resonance Imaging in the Diagnosis of Hypertrophic Cardiomyopathy -- Rickers et al. 112 (6): 855 -- Circulation.

Coronary Artery Calcium Outperforms Carotid Artery Intima-Media Thickness as a Noninvasive Index of Prevalent Coronary Artery Stenosis -- Terry et al. 25 (8): 1723 -- Arteriosclerosis, Thrombosis, and Vascular Biology

Not that it says anything very new, but just one more article on the usefulness of calcium scoring in assessing the risk of coronary artery disease.

Link: Coronary Artery Calcium Outperforms Carotid Artery Intima-Media Thickness as a Noninvasive Index of Prevalent Coronary Artery Stenosis -- Terry et al. 25 (8): 1723 -- Arteriosclerosis, Thrombosis, and Vascular Biology.

Plaque rupture

This article in Auntminnie.com shows how a group of doctors from Minnesota presented evidence of plaque rupture on MSCT, by looking for extravasation of contrast outside the lumen. This sign should be interesting to look at.

Link: Multi-slice CT reveals plaque rupture in coronary arteries

Rapid and complete coronary arterial tree visualization with magnetic resonance imaging: feasibility and diagnostic performance -- Jahnke et al., 10.1093/eurheartj/ehi391 -- European Heart Journal

Snapping on the heels of cardiac CT, is whole heart MRI. There were at least 3 posters on this subject at this year's ECR and there seems to be renewed interest in this subject. It is likely that if the results pan out, we could use whole heart MRI for diffuse calcific disease, where CT really falls short.

Link: Rapid and complete coronary arterial tree visualization with magnetic resonance imaging: feasibility and diagnostic performance -- Jahnke et al., 10.1093/eurheartj/ehi391 -- European Heart Journal.

Anomalous Coronary Arteries in Adults: Depiction at Multi-Detector Row CT Angiography -- Datta et al. 235 (3): 812 -- Radiology

This article is a multi-centre article that describes coronary anomalies seen in 18 patients, using a 4 or 16-slice CT scanner. They have divided the anomalies into a) ectopic origin from a coronary sinus, b)absent coronary artery and c) ectopic origin from a pulmonary artery

Again, keeping in mind the scanner and workstation used, the images are nice.

Link: Anomalous Coronary Arteries in Adults: Depiction at Multi-Detector Row CT Angiography -- Datta et al. 235 (3): 812 -- Radiology.

A Pictorial Review of Coronary Artery Bypass Grafts at Multidetector Row CT -- Marano et al. 127 (4): 1371 -- Chest

This article by Marano et al is a pictorial essay describing the various types of grafts and their appearance on cardiac CT. Since the scanners used are 4-slice and 16-slice, the quality is not as good as those now seen on 64-slice scanners.

Link: A Pictorial Review of Coronary Artery Bypass Grafts at Multidetector Row CT -- Marano et al. 127 (4): 1371 -- Chest.

NEJM -- Long-Term Outcomes of Coronary-Artery Bypass Grafting versus Stent Implantation

This article looks at patients from the New York registry and shows that in patients with two-vessel disease or more, CABG is better than PCI (stent implantation) as far as long-term, overall survival is concerned. The accompanying editorial helps explain this better as well.

Link: NEJM -- Long-Term Outcomes of Coronary-Artery Bypass Grafting versus Stent Implantation.

MDCT Evaluation of the Coronary Arteries, 2004: How We Do It--Data Acquisition, Postprocessing, Display, and Interpretation -- Lawler et al. 184 (5): 1402 -- American Journal of Roentgenology

This article is for 16-slice CT scanners and though most of it can be extrapolated to the newer 64-slice scanners, not all of the material is relevant. This again illustrates the problem with the frustratingly slow pace of publication in radiology - the article was submitted in Feb 2004 and has been published in June 2005.

Among the issues not relevant to 64-slice CT scanners, are those of dose-modulation, contrast injection and timing and phase reconstruction. These will be discussed in detail in the "Images" blog this month.

Link: MDCT Evaluation of the Coronary Arteries, 2004: How We Do It--Data Acquisition, Postprocessing, Display, and Interpretation -- Lawler et al. 184 (5): 1402 -- American Journal of Roentgenology.

JAMA -- Abstract: Noninvasive Coronary Angiography With Multislice Computed Tomography, May 25, 2005, Hoffmann et al. 293 (20): 2471

This is finally the "big" one. Following in the vein of all the previous articles by authors from Germany and Netherlands, this one by Hoffman et al shows how well CT angiography on a 16-slice CT does, as compared to conventional catheter angiography. The negative and positive predictive values are above 90%. As with previous articles, almost all false positive cases are related to the presence of extensive calcification.

Link: JAMA -- Abstract: Noninvasive Coronary Angiography With Multislice Computed Tomography, May 25, 2005, Hoffmann et al. 293 (20): 2471.

Accuracy of MSCT coronary angiography with 64-slice technology: first experience -- Leschka et al., 10.1093/eurheartj/ehi261 -- European Heart Journal

This is the first proper article on the use of 64-slice CT for coronary angiography. Their results are as expected spectacular, with a negative predictive value of 99% - this means that when the test is reported to be normal, it will be normal 99% of the times for ruling out coronary artery disease. The sensitivity was also very good - 94%, which means thatn 94% of all lesions were picked up as well.

All their studies were done using 370ms, rather than 330ms. As more and more experience and expertise is gained, the accuracy levels are bound to go up more. The cases shown in our Images blog, reflect our levels of accuracy as well.

Link: Accuracy of MSCT coronary angiography with 64-slice technology: first experience -- Leschka et al., 10.1093/eurheartj/ehi261 -- European Heart Journal.

Surgery is the best intervention for severe coronary artery disease -- Taggart 330 (7494): 785 -- BMJ

This opinion piece by Dr. Taggart, though controversial (as seen by the number of comments) helps put things in perspective. This is the path by and large followed in India. Severe multi-vessel disease is best treated with a CABG, whereas single or two vessel disease with single stenotic lesions, are best treated by PCI (percutaneous coronary intervention) using stents, most usually drug-elutin.

Link: Surgery is the best intervention for severe coronary artery disease -- Taggart 330 (7494): 785 -- BMJ.

Late gadolinium-enhanced magnetic resonance imaging in acute and chronic myocardial infarction: improved prediction of regional myocardial contraction in the chronic state by measuring thickness of nonenhanced myocardium.

This article in the Mar 2005 issue of JACC compares many parameters in patients with acute infarcts imaged during the acute episode and later in the chronic phase, using CMR/MRI with delayed hyperenhancement. They form the following conclusions
1. Acute infarcts as defined by the areas of enhancement reduce in size in the chronic phase, probably due to contracture of scar tissue.
2. The non-enhancing myocardium increases as well probably due to compensatory hypertrophy.
3. The thickness of the non-enhancing myocardium (>5.1mm) in the chronic phase and >3.9mm in the acute phase predicts functional recovery with good sensitivity and specificity.
4. Percentage transmural involvement of the myocardium by infarction correlates with functional recovery with the same specificity and sensitivity as with other studies done previously.