Non-electrocardiogram-gated and Non-contrast-enhanced Magnetic Resonance Angiography of the Lower Limb Arteries Using Three-dimensional Multishot T₁-weighted Fast-field Echo-Echo Planar Imaging

Abstract

We performed a non-electrocardiogram-gated and non-contrast-enhanced magnetic resonance angiography (MRA) of the lower limb arteries using three-dimensional multishot T 1 -weighted fast-field echo-echo planar imaging (3D multishot T 1 -FFE-EPI), and it was optimized the protocol. The image distortion for the change in the EPI factor was calculated using 3.0 T-MRI and MRI phantom. We also calculated the signal-to-noise ratio (SNR) of the femoral artery with a change in the flip angle on images of 8 healthy volunteers. Furthermore, the optimal EPI factor was determined from the SNR of the femoral artery and the contrast ratio between the femoral artery and the adductor magnus. Two radiological technologists performed a retrospective visual assessment of the pelvis, thigh, and leg of 10 patients who underwent lower limb non-contrast-enhanced MRA and contrast-enhanced tomography angiography (CTA). The optimum flip angle and EPI factor were 25° and 3, respectively. In the visual assessment of clinical cases, there was no significant difference between the non-contrast-enhanced MRA and contrast-enhanced CTA in the pelvis and the leg (p=0.52 and p=0.88, respectively). In the thigh, non-contrastenhanced MRA was significantly higher (p=0.02), namely, the ability to visualize the lower limb arteries was not much difference between this method and contrast-enhanced CTA. Our method without electrocardiogram gated and contrast medium is expected for screening tests or detailed examinations.