Improved functional cardiac MR imaging using the intravascular contrast agent CLARISCAN

Area of Science:

• Cardiovascular Magnetic Resonance Imaging
• Medical Imaging Techniques
• Radiology

Background:

• Segmented k-space turbo gradient echo (TGE) MR techniques often show reduced blood-myocardium contrast in long axis views.
• This contrast reduction is particularly pronounced in patients with low ejection fraction, impacting endocardial border delineation.

Purpose of the Study:

• To evaluate the efficacy of intravascular contrast agents (CA) in improving endocardial border delineation and left ventricular function assessment using TGE MR.
• To determine the optimal dose of CA for enhanced image quality and diagnostic accuracy.

Main Methods:

• Cardiac cine loops were acquired in 15 patients using TGE sequences with varying doses of CA (0.75, 2.0, 5.0 mg Fe/kg).
• Left ventricular ejection fraction (LVEF) and endocardial border delineation scores were assessed by two independent observers.
• Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) between blood and myocardium were quantified.

Main Results:

• Endocardial border delineation scores significantly improved with increasing CA doses (p < 0.01).
• Blood SNR increased significantly, while myocardial SNR slightly decreased, leading to a >2-fold increase in CNR blood/myocardium at 2.0 mg Fe/kg.
• Inter- and intraobserver variability for LVEF determination was reduced, particularly for patients with LVEF <50%.

Conclusions:

• Intravascular CA significantly enhances CNR between blood and myocardium, improving cardiac volume determination.
• The accuracy of cardiac imaging and LVEF assessment is most improved in patients with left ventricular ejection fraction below 50%.