Читать книгу Leksell Radiosurgery - Группа авторов - Страница 57

Angiography is the gold standard for AVM radiosurgery planning. It should be used in conjunction with MRI or CT imaging to provide the third imaging dimension. The technique of angiography differs slightly from the conventional digital angiography as the stereotactic angiographic images are used not only for AVM nidus definition but also to guide radiation to the target. The orthogonal images (instead of oblique or rotated) are preferred but are not necessary. For AVM nidi that are not properly visualized in orthogonal planes a rotation of up to 10° in 2 dimensions can be used without compromising the accuracy of radiation delivery [5]. Digital subtraction techniques, despite a potential radial distortion error, have proven satisfactory. We suggest that a radiosurgery team member review the angiogram prior to removing the angiography catheter to make sure that:

1. The target AVM nidus is clearly visualized and is within the fiducial space

2. All 9 of the fiducials of angiographic localizer are seen on the images

3. Subtraction is performed in front of the treating physician to ensure that fiducial markers are still visible after the subtraction

4. The best AP and lateral images during the early capillary phase (with just the appearance of draining veins) are selected and exported to GammaPlan workstations.