Cardiac radiology enters vital new phase

Cardiac imaging is at a crossroads, according to next year's ECR president. He's not alone in holding such an opinion.

Advances in CT and MR are expanding the role of these modalities, and highly promising results from coronary CT angiography are boosting the demand for 64-slice CT scanners. But uncertainty remains, said Prof. Borut Marincek, chair at the Institute of Diagnostic Radiology at Zurich University Hospital.

He listed several key areas of concern in cardiac imaging, including the ongoing definition of applications, high expectations of users and vendors, competition between professional organizations and societies, the need for quality measures, cardiac experts providing interpretations by means of teleradiology, and collaboration among radiology, cardiology, and others.

The ESR's 2007 survey results, based on 138 responses from European radiology departments performing cardiac CT and MR, confirmed that cardiac imaging is mainly carried out by radiologists in university hospitals, Marincek told attendees at Saturday's special focus session, at which he was the moderator.

The survey also found that most radiologists are offering only a daytime cardiac imaging service, and many of them are afraid of losing work to other specialties. A lack of clinical training and limited experience of cases during their residency are seen as major obstacles facing radiologists who wish to become experts in cardiac imaging.

CT can broadly, but not completely, cover a large proportion of cardiac imaging, and it is an excellent tool for noninvasive imaging of the coronary arteries and ventricular dimensions and function, according to Dr. Hatem Alkadhi, also of the institute at Zurich. The modality has some potential for assessing valvular function and myocardial viability but no role in perfusion imaging.

"CT for myocardial perfusion measurements is usually not performed because of radiation dose issues," he said.

For the epicardium and pericardium, the primary imaging modality is MRI, Alkadhi said. The second-line modality is CT, particularly when a lesion extends beyond the epicardium or pericardium.

MRI, on the other hand, is widely accepted as the gold standard for volume and muscle mass quantification, according to Prof. Matthias Gutberlet, a professor of cardiovascular imaging at the University of Leipzig in Germany. Tissue characterization and localization allow differential diagnosis. Delayed-enhancement MR is the established method for viability assessment, but it is not specific.

MR flow measurement allows absolute quantification of flow (shunts, insufficiency), but MRI visualisation of coronary arteries is still challenging and MR perfusion in daily routine lacks robustness, he said. Both these areas can benefit from the use of higher field strengths and parallel imaging.

Different diagnostic strategies are required for both primary and secondary prevention of cardiovascular morbidity and mortality, said Prof. Valentin Sinitsyn of the Cardiology Center in Moscow. Whereas calcium scoring and ultrasound are needed for primary screening of cardiovascular diseases, a different approach is necessary for coronary CT angiography, assessment of myocardial function and perfusion, and examinations of flow and valve function. Uncertainty surrounds the precise role of MSCT and MRI in the workup of cardiac diseases.

MSCT has turned into a useful tool for noninvasive coronary imaging, including acute coronary syndromes and pulmonary veins, while MRI has emerged as a valuable method for assessment of myocardial viability and perfusion, he said.

Unanswered questions remain: Who will perform and interpret cardiac CT and MRI examinations? Will it be those who have the knowledge or those who have access to the equipment?

Sinitsyn believes it will be radiologists, but much will depend on their skill and activity in cardiac CT angiography and MRI, and whether they can cooperate successfully with cardiologists.