Coronary Artery Calcium Scoring

Introduction

Subsecond helical CT with cardiac gated images allows the detection and quantification of coronary artery calcification. This examination is available at St George's Radiology on the dual-source 64 slice Siemens  scanner.

This critical information is acquired in a quick and comfortable exam that doesn't require any patient preparation or contrast.

Overview

Calcium accumulates in the arteries in an age-related manner. The presence and extent of coronary calcium deposition seem to be closely related to overall atherosclerotic plaque burden. Electron beam and multidetector CT are sensitive means of detecting coronary arterial calcium.

Evidence suggests that although a negative coronary CT calcium study (i.e. zero calcium score) does not completely exclude the presence of atherosclerotic plaque, it does imply a very low likelihood of significant luminal obstruction. Conversely, a high calcium score is consistent with a moderate to high risk of a coronary event within two-five years.

Among noninvasive techniques, coronary calcium screening with multidetector CT is an effective predictor of future coronary events and there is evidence that it is a better predictor than all other risk factors combined.

Availability

This study is available only on referral from a specialist cardiologist and will be part of an overall cardiac assessment.  As with all CT examinations the relatively high radiation dose compared with conventional xrays needs to be considered. Also, now that CT can evaluate the actual lumen of the coronary arteries in addition to the load of calcified plaque, a full CT coronary arteriogram is usually preferred over calcium scoring alone.

Coronary Artery Calcium Scoring is inappropriate for acute symptomatic patients and those with a past history of myocardial infarction or coronary artery bypass surgery.

Cost

See Fees

Time Required

While the scan is completed in one breath-hold about 15-20 minutes will be needed on the scanner with an overall appointment time of 30 minutes. Data processing after the scan is time consuming and generally results will not be available immediately. The results will be in the form of a written report and will include a table outlining possible clinical action (see attached table 1).