Cardiac CT & MRI Literature

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.

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.

Real-time cine MRI in constrictive pericarditis

In normal situations there is a phenomenon called ventricular coupling or interventricular dependence wherein the function of one ventricle is altered by changes in the filling of the other. As a result, the septum always maintains a right-ward bowing.

In constrictive pericarditis, this coupling is lost. As a result, the septum shows dyskinetic and often paradoxical movement. Specifically in inspiration, when there is a reduction in intra-thoracic pressure with an increase in systemic venous return and a reduction in pulmonary venous return, the dilated RV results in left-ward bowing of the septum.

Real-time MRI can assess this well. With this technique, described by Francone M et al in the March issue of the Journal of Magnetic Resonance Imaging, during the onset of inspiration, the real-time study can easily show the abrupt left-ward shift or flattening of the septum. This reduces in expiration and with successive heart-beats.

Flattening is also seen with pulmonary hypertension, but this is fixed and does not change with the phase of respiration.

Delayed hyperenhancement in ARVD

The January issue of JACC has an article  by Tandri H et al on the use of delayed hypenhancement in the assessment of arrhythmogenic right ventricular cardiomyopathy (ARVD). Apart from the traditional criteria of fat infiltration and dyskinetic segments in the RV, this is a new sign for which they found excellent correction with histopathology and predicted inducible VT on programmed electrical stimulation.

This suggests that it may worthwhile changing the ARVD protocol to include delayed hyperenhancement.

See the accompany case in the "images" blog.

CMR in non-compaction

This is another case report in Heart, on the use of CMR in diagnosing non-compaction. This patient had severe LV dysfunction with abnormal septal enhancement that was proven to be fibrosis on pathology after the patient underwent heart transplantation. Non-compaction often is an incidental finding and not significant.

Myocarditis and CMR

This is a case report by Verghese et al from the Royal Brompton group on the use of CMR in myocarditis. As expected there are areas of myocardial enhancement that are not typical of infarcts.

Endomyocardial fibrosis - case

An interesting case of biopsy proved endomyocardial fibrosis, by Cury R C et al,  has been published in a recent issue of Circulation.

Images published include those of a cardiac cath and MRI, both cine and delayed hyperenhanced images, which show diffuse subendocardial enhancement.

Cardiac sarcoidosis

This is a pictorial essay on the MRI features seen in cardiac sarcoidosis, published by Vignaux O, in the January issue of the AJR. Patients with cardiac sarcoid show involvement of the myocardium with varying degrees of inflammation, granuloma formation and scarring. Acute edema and inflammation can be seen on T2W images, whereas the rest of the features require a combination of delayed hyperenhanced images and cine images.

Two representative cases are available in the accompanying images blog for viewing, one published today and one in January.

Acute and reversible cardiomyopathy due to stress

This is a report from Minneapolis, by Sharkey et al, in Circulation, of a group of 22 patients who had a specific syndrome of acute reversible cardiomyopathy following an episode of profound psychological or physical stress.

All these patients had a typical CMR appearance, with no delayed hyperenhancement, but with areas of dyskinesia and hypokinesia in the mid and distal LV. The recovery was spontaneous, but needed supportive management.

This pattern of involvement has been earlier described in Japanese literature as the tako-tsubo syndrome.