Removal of arterial wall XXXX in CT angiography by local subtraction.

@entity730 @entity1 @entity850 @entity1213
CT Angiography (CTA) is an established technique for the minimally invasive imaging of arteries. The technique of @entity1213 ( @entity1213 ) is often used to get a comprehensive overview of the vascular anatomy. On a @entity1213 , however, arterial wall @entity730 may hinder the visualization of the arterial lumen. These @entity730 are in direct contact with the contrast-enhanced blood, which makes removal difficult. We present a local subtraction method for the automatic removal of these @entity730 . In our approach a second CT scan has to be made, prior to contrast injection. The @entity730 in both scans are registered prior to subtraction to compensate for displacements in between the two scans. Local subtraction results are compared with results obtained by thresholding. The method was tested in a phantom and with data from four @entity1 . The phantom represented an artery with different types of @entity850 . Data were used from @entity1 for which CTA of the renal arteries was performed. For two @entity1 the electrocardiogram (ECG) was recorded during the CTA examination, making retrospective cardiac gated reconstructions possible. Both the phantom and the @entity1 study showed that the local subtraction method is capable of removing @entity730 and visualizing the residual lumen. In the @entity1 study it appeared that some artifacts remained for higher pitch values. We conclude that the local subtraction method is less subjective and more accurate than thresholding. Best results are obtained by use of a small pitch, at the expense of the volume covered during a single breath hold.
