The intracerebral vasculature is enormously complex. Operations on tumors and vascular lesions are difficult partially because surgical excision requires interrupting the lesion's blood supply. However, some supplying arteries may have child branches supplying normal brain. If such a parent vessel is interrupted, the patient may suffer a stroke. The complex, connected vascular network is very difficult to visualize in 3D. 

Unfortunately, no clinical imaging method provides the requisite 3D vascular parent-child information. It is important to develop methods for displaying complex vascular anatomy to illustrate vessel connectivity. 

Blood vessel supplying a tumor (left) and blood vessel supplying both tumor and normal brain (right). Intraoperatively, it can be enormously difficult to distinguish one from the other. 

Formal evaluation of the accuracy of parent-child connections in 7 vascular trees by two independent neuroradiologists indicate that the 95% confidence interval for the proportion of fully correct connections is in the range of (91% - 99%). We have also developed programs for surgical display that allow simultaneous visualizations of volume rendered regions (tumor or AVM nidus) with our vessel trees. Individual subtrees can be color coded or selectively turned off to prevent obscuration. A number of other visualizations are available. The program runs on a laptop PC and is used actively clinically. 

Surgical planning interface showing a volume-rendered AVM nidus and a color-coded vascular tree supplying it. Slice data is shown in the window at right. The patient has a frontal AVM supplied by a single carotid circulation. 
 

Other visualizations include display of color-coded vessels against MRA slice data, or as projected against a digital subtraction angiogram (DSA) of the same patient. The patient is the same as shown immediately above. 
 

Complex AVM fed by multiple trees.
A. Vessels alone.
B. The blue carotid tree has been removed with a single point and click. The volume-rendered nidus is also shown, with arrows indicating passage of vessels into the nidus.
C. Volume rendered nidus at full opacity.
D. Automatic determination of potential feeding vessels (red). 

• Image-Guided Endovascular Neurosurgery 

Bullitt E, Liu A, Aylward SR, Soltys M, Boxwala A, Rosenman J, Pizer S (1997a) Methods for displaying intracerebral vascular anatomy. Am J Neuroradiol 18:417-420. 

Bullitt E, Aylward S, Liu A, Stone J, Mukherji S, Coffey C, Gerig G, Pizer SM (1999) 3D graph description of the intracerebral vasculature from segmented MRA and tests of accuracy by comparison with x-ray angiograms IPMI 99 Lecture Notes in Computer Science 1613:308-321. 

Bullitt E, Liu A, Aylward S, Coffey C, Stone J, Mukherji SK, Muller K, Pizer SM (1999) Registration of 3D vessels with 2D digital angiograms. Clinical evaluation.. Academic Radiology 6: 539-546. 

• Dr. Elizabeth Bullitt 
• Dr. Stephen R. Aylward 
• Dr. Guido Gerig 
• MIDAG