Clinical usefulness of 3-D CT endoscopic imaging of cerebral aneurysms

Treatment of Cerebral Aneurysms: Surgical, Endovascular or Combined Intervention

A retrospective study of 437 cases of cerebral aneurysms over a 4 year period is reported. Surgical clipping was performed in 322 cases (254 ruptured and 68 incidental aneurysms) and endovascular embolization was done in 50 cases (26 ruptured and 24 incidental aneurysms). No intervention (either surgical or endovascular) was performed in 65 patients. In the direct surgical treatment group, mortality was 1.5% in incidental and 9.8% in ruptured aneurysms and good recovery was seen in 98.5% and 74.8% cases respectively.

In the endovascular intervention group, results were poor due to the severity of their neurological grading and older age. Mortality was 42.3% in ruptured and 4.2% in incidental aneurysms. Six out of 26 ruptured and 11 out 24 incidental aneurysm patients had complications in the endovascular treatment group. We have discussed the results and indications for both modes of treatment in our study.

Management of complex, surgically intractable intracranial aneurysms: the option for intentional reconstruction of aneurysm neck followed by endovascular coiling

BACKGROUND

A limited series of patients with aneurysm were reviewed retrospectively to analyze strategies for integrating microsurgical and endovascular techniques in the management of complex, surgically intractable aneurysms.

METHODS

Four patients were managed in Fujita Health University with a multimodality approach: intentional reconstruction of the aneurysm neck followed by endovascular coiling.

RESULTS

A total of 5 aneurysms were treated, of which 3 were large or giant in size, and 3 were fusiform or multilobulated. Complete angiographic obliteration was confirmed in 4 aneurysms (80%). All patients had a good outcome (Glasgow Outcome Scale score 5; mean follow-up, 64 months).

CONCLUSION

As for complex, surgically intractable aneurysms, the intentional reconstruction of the aneurysm neck followed by endovascular coiling should be considered more often.

Transluminal imaging with perspective volume rendering of computed tomographic angiography for the delineation of cerebral aneurysms

Transluminal imaging with perspective volume rendering of computed tomographic angiography was used to investigate three patients with unruptured cerebral aneurysms. Selective changes in the opacity chart of computed tomography values, based on a spiked peak curve, represented the contour of the vessel and aneurysmal walls as a series of rings, and allowed a transluminal view from outside or inside the vessel lumen through the spaces between the rings. This imaging technique provided direct visualization of the underlying structures and an extensive perspective view of the cerebral aneurysms, including the parent arteries and surrounding bony structures, through the overlying vessel and aneurysmal walls. Transluminal imaging may be a useful method for the extra- and intraluminal diagnosis of a cerebral aneurysm, and for simulation of the interventional and surgical procedures considered for cerebral aneurysms.

Simulation of the surgical manipulation involved in clipping a basilar artery aneurysm: concepts of virtual clipping. Technical note

Despite recent advances in three-dimensional imaging based on a voxel-rendering method, these techniques do not simulate the morphological changes that occur during surgery. The authors' goal was to develop a computer-graphics model to simulate the manipulation that occurs during surgery when clipping a cerebral aneurysm. The authors developed an application program to interpolate the contours of models of an artery and an aneurysm clip. The center of displacement was determined inside the arterial model. The directions of displacement were changed to simulate saccular and broad-neck aneurysms, and the intensity of displacement was calculated by using a cosine-based formula. The morphological changes in a saccular aneurysm that may occur during clipping were calculated in x, y, and z coordinates by using sine- and cosine-based formulas. Clip movement was integrated with the aneurysm model, thus simulating the manipulation used during clipping of a cerebral aneurysm. Surgery performed to clip a basilar artery (BA) aneurysm via the transsylvian approach was simulated, in which displacement of the internal carotid artery and clipping of the BA aneurysm were necessary. The movements of an aneurysm clip and clip applicator were designed to represent those occurring when a surgeon actually manipulates a BA aneurysm. The authors have named this methodological tool "virtual clipping." Use of this tool would assist the preoperative choice of clipping style and selection of the best clip.

Application of three-dimensional CT angiography (3D-CTA) to cerebral aneurysms

BACKGROUND

3D CT angiography (3D-CTA) is a noninvasive imaging modality for cerebral aneurysms. 3D-CTA is helpful in the evaluation of the configuration of the aneurysm, the surrounding vessels, and the inside of the aneurysm dome. Clinical application of this technique in complicated large cerebral aneurysms showed that with 3D-CT endoscopic imaging, anatomical details of cerebral aneurysms such as the orifice of the aneurysm, intraluminal thrombus, and calcification of the wall could be clearly demonstrated. Using the 3D-imaging method with helical CT, virtual views of various surgical approaches can be compared preoperatively. This information was found to be very useful for determining difficult aneurysms for coil embolization or direct surgery including complicated and broad-based aneurysms.

METHODS

Helical CT scanners (TOSHIBA X-vigor) are used for intracranial vascular lesions. At present, nearly stereoscopic images at a pixel size of 0.35 x 0.35 x 0.4 mm are obtained by reconstruction under the following conditions: slice thickness, 0.8 mm; couch top speed, 1.0 mm/ sec.; 130 kV; 220 mA; visual field, 18 cm in diameter (11 cm after extension); pitch, 0.4 mm; and opposed beam interpolation. RESULTS AND CLINICAL APPLICATION: By virtual vascular 3D-CT endoscopy, the lumen of the cerebral aneurysm is displayed by the surface rendering method. Its clinical applications include 1) Demonstration of three-dimensional aneurysm morphology, including the dome and the neck region; 2) Preoperative simulation; 3) Confirmation of parent blood vessels flowing into and out of aneurysms and visualization of aneurysmal lumen calcification. Coronal and sagittal sections can demonstrate whether the branches arise from the aneurysm or aneurysmal neck. The limitation of 3D-CTA is in delineating perforating arteries that are less than 1.2 mm in diameter. The problem with virtual vascular 3D-CT endoscopic images is that endoscopic findings in the vascular wall are incomplete because of the partial volume effect and pulsation of the aneurysm and vascular wall.

CONCLUSIONS

Helical Scanning-CT (HES-CT) is an excellent noninvasive diagnostic modality for cerebral aneurysm detection. 3D-CT angiography has distinct advantages in evaluating aneurysms and selecting the most appropriate therapeutic modality.