Late enhancement using multidetector row computer tomography: a feasibility study with low dose 80 kV protocol

Detecting stenoses of coronary arteries with multidetector row computer tomography (MDCT) is a well feasible non-invasive method. However, there is still the problem of deciding whether a stenosis is hemodynamically relevant or not. Objective of the present study was to validate the feasibility of a low dose protocol for MDCT using 80 kV for detecting late enhancement.

Using a Alderson-Rando Phantom evaluation of the effective dose of this LE protocol was performed. Ten patients (six male, four female, mean age 61) with known coronary artery disease and scheduled for a conventional coronary angiogram in our facility were subsequently recruited. All patients underwent CT-angiography (CTA) 1 day prior to magnetic resonance imaging. Five minutes after the application of 100ml contrast agent for the CTA scan, a low dose late enhancement scan (80 kV, 400 mA s maximum, ECG pulsed scan, 64 mm x 0.6mm collimation, 0.33 s tube rotation) was performed. Phantom dose measurements showed an effective dose for this protocol of 1.19 mSv (male) and 1.61 mSv (female). Fifty-six percent (5/9) of the patients showed a late enhancement on the MRI scan. Three transmural late enhancements and all four negative findings were correctly identified by CT. This represents a sensitivity of 78% (3/5), specificity of 100% (3/3), NPV of 100% (4/4) and a PPV of 97%.

We were able to show that the low dose protocol is feasible and, furthermore, preliminary results look promising.