Feasibility of a radiation dose conserving CT protocol for myocardial function assessment

Area of Science:

• Cardiovascular Imaging
• Radiology
• Medical Physics

Background:

• Myocardial function assessment requires higher noise tolerance than coronary arterial evaluation.
• Optimizing radiation dose while maintaining diagnostic image quality is crucial in cardiac CT.

Purpose of the Study:

• To evaluate image quality and radiation exposure of a dose-conserving, function-only CT acquisition compared to standard retrospectively electrocardiogram (ECG)-gated coronary CT angiography (CTA).

Main Methods:

• A prospective study compared a low-dose, prospectively ECG-triggered function-only CT acquisition (Group I) with a standard retrospectively ECG-gated coronary CTA protocol (Group II).
• Image quality was assessed using contrast-to-noise ratio (CNR) and visual indices.
• Radiation exposure was quantified by dose-length product.

Main Results:

• Group I demonstrated preserved CNR throughout the cardiac cycle, unlike Group II.
• Visual image quality was comparable at end systole but superior in Group II at end diastole.
• Total radiation exposure was similar between groups (284 vs. 280 mGy cm), with a median of 138 mGy cm for the dedicated function scan in Group I.

Conclusions:

• A low-dose retrospective ECG-gated protocol enables myocardial function assessment at a median radiation exposure of 138 mGy cm.
• This protocol provides more consistent multiphase CNR compared to traditional ECG-modulation protocols.
• The findings support the use of tailored CT protocols for pure functional evaluation or as an adjunct to single-phase scans, limiting radiation exposure while maintaining image quality.