Improved image quality in subtraction based non-contrast MRA using automated soft tissue motion correction with BRACE
© Fan et al; licensee BioMed Central Ltd. 2009
Published: 28 January 2009
Recently several new approaches for non-contrast MRA have been proposed. Many of them are based on subtraction of two 3D data sets, which are acquired either at two different points of the cardiac cycle, eg NATIVE SPACE or use different preparation mechnisms to alter the signal intensity in the arteries and veins, eg by flow sensitizing dephasing (FSD)gradients. As the acquisition of each dataset takes in the order of 2–3 minutes, motion can occur in between the two acquisitons and can impair therefore the resulting image quality. A common problem which is also known from contrast enhanced MRA, where the mask is subtracted form the contrast data set .
To evaluate in volunteers and patients whether an automated soft tissue motion correction software can improve the image quality of subtraction based non-contrast MRA data.
Non contrast peripheral MRA data sets of the lower legs of 3 healthy volunteers and 3 patients where qualitatively scored before and after motion correction by an experienced radiologist. The commecially available software syngo BRACE (Siemens Healthcare, Germany) was used  to perform the automated motion correction of the two data sets.
Qualitative image quality was assed using a scale from 1 to 4 (1 being poor, 2 fair, 3 good, 4 excellent vessel conspicuity) The conspicuity was scored for the popliteal, anterior tibial, posterior tibial and the peroneal branch as well as for the side branches. A score was given for each branch before and after motion correction.
The motion correction software BRACE was able to improve the image quality in subtraction based non contrast MRA techniques when motion occued. Many cases showed that motion often occurs in only one leg. In those cases BRACE did not deteriorate the image quality of the leg without motion while at the same time improving the result in the leg affected by motion. No case was observed where the software did decrease the image quality compared to the uncorrected image. BRACE therefore provides a promising tool in the area of non contrast MRA.
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