High spatial resolution MRA of renal arteries using contrast behavior between fat and water during transient phase before reaching a steady state

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• 作者：Katsuhiro Kida^a ; ^b ; ^{dhe19506@s.okayama-u.ac.jp} ; Sachiko Goto^b ; ¹ ; ^{goto@md.okayama-u.ac.jp} ; Yoshiharu Azuma^b ; ¹ ; ^{azuma@md.okayama-u.ac.jp}
• 关键词：Renal MRA ; Transient phase ; High spatial resolution ; Isotropic voxel ; MIP image ; Visual evaluation
• 刊名：European Journal of Radiology
• 出版年：2012
• 期刊代码：93_0720048x
• 类别：med
• 出版时间：May, 2012
• 卷：81
• 期：5
• 页码：846-850
• 文件大小：525 K

摘要

Purpose

Our aim is high spatial resolution imaging of maximum intensity projection (MIP) images in renal magnetic resonance angiography (MRA) by constructing a protocol for acquiring three-dimensional volume data with isotropic voxels.

Materials and methods

We eliminated water-selective excitation (WATS) and utilized effective contrast behavior between fat and water before reaching a steady state鈥攖hat is, during the transient phase鈥攖o cover fat suppression by WATS. In a phantom study, the optimal flip angle was investigated under the 鈥渓ow-high Y鈥?profile order using distilled water and baby oil to construct a protocol with isotropic voxels. Signal intensity, contrast, noise and signal-to-noise ratio were investigated to compare image qualities between the conventional and the constructed isotropic protocols. In a clinical study, three radiologists and two radiological technologists visually evaluated clinical images of 20 volunteers for spatial resolution, contrast and overall reader confidence in two protocols.

Results

We constructed an isotropic protocol with voxel dimensions of 0.78 mm 脳 0.78 mm 脳 0.78 mm at a flip angle of 90掳. We maintained the scan time but enlarged the x-y pixel dimensions from 0.59 mm 脳 0.59 mm to 0.78 mm 脳 0.78 mm and shortened image height from 48 mm to 42.9 mm. Data from the phantom study were worse in the isotropic protocol than in the conventional protocol. However, overall reader confidence in the clinical images was significantly better in the isotropic protocol than in the conventional protocol (p < .001).

Conclusion

Our study indicated the value of addressing high spatial resolution imaging of MIP images for renal MRA by constructing an isotropic protocol.