Cardiac CT & MRI Literature

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.

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.

CMR predictors of aortic coarctation severity

This article from Boston, by Nielson J et al, in Circulation, describes the use of CMR in assessing the severity of coarctation of the aorta.

Their results are as follows:
"By logistic regression analysis, the following variables simultaneously predicted coarctation gradient 20 mm Hg: (1) smallest aortic cross-sectional area (adjusted for body surface area) measured by planimetry from gadolinium-enhanced 3D magnetic resonance angiography (OR 1.71 for 10 mm²/m² decrease, P=0.005) and (2) heart rate–corrected mean flow deceleration in the descending aorta measured by phase-velocity cine MRI (OR 1.68 for 100 mL/s^1.5 increase, P=0.018). For the combination of these variables, a predicted probability >0.38 had 95% sensitivity, 82% specificity, 90% positive and negative predictive values, and an area under the receiver-operator characteristics curve of 0.938. In a subsequent validation study, the prediction model correctly classified 9 of 10 patients, with no false-negatives."

In effect, CMR in nine out of 10 patients, using a combination of planimetry and flow measurements was able to predict the need for intervention, using the criterion of a pressure gradient of 20mmHg or more, as measured by cardiac catheterization.

Myocardial bridging

This has relevance to the post on our companion images blog.

Myocardial bridging is a condition that occurs when the myocardium covers a part of the coronary artery; usually the LV covering part of the LAD, such that the artery runs through the myocardium and is subject to systolic reduction in calibre. An excellent image was published in NEJM in 2003.

The consensus regarding its significance is lacking, however there are anecdotal reports of patients with myocardial bridging presenting with acute coronary syndromes. Please see this report by Sciahbasi A et al and Low et al.

One study published by Teragawa H et al in Clinical Cardiology in 2003 shows that following intracoronary nitroglycerine, patients with bridging experience more incidents of spasm and the authors suggest that this may be a cause of related cardiac events in this group of patients.

Multiple posts from blog.refindia.net

There are multiple entries in the cardiac section at blog.refindia.net that should be of interest as well. Eventually I will try and import them into this blog as well.