These objects were then integrated, and displayed on a Sun computer workstation Ultra-1; Sun Microsystems, Inc. In this software, each object can be individually colored, made translucent, removed, rotated, translated and scaled as the viewer wishes. The entire process, from scanned data to 3D model took hours per patient, and the average time was 6 hours. For a complicated AVM case, a flow analysis was performed using velocity information in the 3 orthogonal directions of a 3D-phase contrast MR angiogram [ 4 ] to define feeding arteries and draining veins.
Surgical planning : We used the 3D model for four purposes:. To facilitate selection of the appropriate intervention i. To visualize the normal and pathologic relationships as well as selecting the surgical approach non-invasively and preoperatively.
To localize lesions intraoperatively in conjunction with video registration [ 14 , 20 ]. The models were also used preoperatively to enhance resident training. Outcome: Patients were assessed immediately after treatment and three months after invasive procedures. Both patients who received radiation treatment had two year follow-up. Outcome was graded as excellent in patients with no new neurologic deficit, good in patients with new but minor neurologic deficits, poor in patients requiring assistance.
Results and illustrative cases. Of the 16 patients preoperatively evaluated in the Surgical Planning Laboratory, 9 underwent surgery alone, 2 had embolization plus surgery, 2 patients were treated with stereotactic radiosurgery, one patient had surgery plus intravascular coil placement, and one patient did not need therapy after a correct diagnosis was rendered. The last patient refused any therapy. The imaging data collected in the laboratory for all cases was needed to obtain a diagnosis.
The term "digital" refers to the clinician's use of a lubricated finger to conduct the exam. Includes the gallbladder and tubular structures called ducts that course through the liver. You can please a ed none and understand your countries. Of the 16 patients preoperatively evaluated in the Surgical Planning Laboratory, 9 underwent surgery alone, 2 had embolization plus surgery, 2 patients were treated with stereotactic radiosurgery, one patient had surgery plus intravascular coil placement, and one patient did not need therapy after a correct diagnosis was rendered. Seller Inventory From this time on, technical advances, anatomical findings, therapeutic tests such as embolization, development of stereo taxy, and computerized axial tomography have opened a wide field for cerebral angiography.
The pre- and postoperative diagnosis' were identical in all cases. One patient thought to have a left middle cerebral bifurcation aneurysm only had a tortuous vessel and did not need intervention. In addition to diagnosis, the surgical planning data was useful in selecting an appropriate intervention.
Two cases were treated with stereotactic radiosurgery on the basis of their radiographic diagnosis, volume calculations and location within eloquent cortex. The planning data indicated the lesion volume was within the limits set for radiosurgical methods and that the vessels were within eloquent cortex, eliminating surgical excision as a therapeutic option. In all surgical cases, the 3D imaging allowed accurate evaluation of the lesions anatomic location and relationships as well as feeding and draining vessel anatomy.
In addition, the images allowed preoperative evaluation of various surgical approaches and the impact each approach might have on surrounding anatomy i.
Video registration techniques were successfully used in cases 15 and 16 for intraoperative localization subcortically located cavernous malformations. The outcome in all surgical and radiosurgical cases was excellent. Case 9 This year old male patient presented with chronic headache. Postcontrast CT and MR images showed a suspected aneurysm in his left middle cerebral artery. The frontal view of the 3D-time of flight MR angiogram indicated the possibility of a coiling vessel Figure 1A.
A 3D reconstruction was made from the original 60 MR angiogram images. Thus, the patient did not need further evaluation or treatment.
The quality of the reconstructions was so precise, an angiogram was not recommended. Frontal view of the maximum intensity projection display of an MR angiogram shows a suspected left middle cerebral artery aneurysm arrow. Oblique frontal view of the 3D model shows coiling of the left middle cerebral artery arrow and M1 segment of left middle cerebral artery arrowhead. Left lateral view of the 3D model also shows coiling of the left middle cerebral artery arrow.
Case 13 This year old female patient presented with an incidental AVM.
Analysis of 3D flow direction [ 4 , 21 ] on the 3D model demonstrated outflow of two vessels from the nidus Figure 2D. Therefore, these vessels were thought to be deep-seated draining veins, and one of these veins flew into the straight sinus via the great vein of Galen. Multiple surgical approaches were evaluated in the laboratory and the result of these efforts indicated moderate risk for morbidity.
Given the surgical risk, the patient elected to undergo stereotactic radiosurgery. Frontal view of the cerebral angiogram showing the nidus fed by the right posterior cerebral artery and draining into the straight sinus. The right lateral view of the MR angiogram showing the AVM fed by the basilar artery double arrows and right posterior cerebral artery arrow head. The long arrow and short arrow indicate the starting points of flow direction analysis. The lines show the flow direction from the nidus. The long arrow and short arrow show the same points as Figure 2C.
Case 8 This year old male patient presented with a sudden and severe headache. The MRI showed an intraventricular hemorrhage. The nidus seemed to be close to the inferomedial wall of the left trigone. An occipital transcortical, transventricular approach provided a straight trajectory and a wide working space after evacuating the hematoma in the trigone. The disadvantage of the approach was that it potentially damaged the optic radiations Figure 3C.
The 3D model showed another possible approach, suboccipital supratentorial. There was no large bridging vein between the left transverse sinus and the occipital lobe close to the approaching site. This approach seemed not to damage the visual cortex nor the optic radiations and was eventually used Figure 3D.
The nidus was entirely removed without neurologic deficit. Left posterior view of the 3D model. The superior sagittal sinus and left transverse sinus are colored in blue. Computer-assisted simulation of the transcortical, transventricular approach to the nidus. The nidus green, asterisk , the intraventricular hematoma pink , superior sagittal sinus arrow , straight sinus double arrows and transverse sinus arrow head are displayed.
Computer-assisted simulation of the suboccipital, supratentorial approach to the nidus. Cerebrovascular diseases with potential surgical indications include aneurysms, AVMs, cavernous malformations and occlusive vascular diseases.
The current routine examination for these diseases are cerebral angiography and DSA. In addition, 3D-CT angiography [ 2 , 6 , 16 , 22 , 25 ] and MR angiogram [ 11 , 12 ] have become available. These new modalities are less invasive and the image quality is steadily improving. However, there are still some limitations associated with these new techniques. For example, the maximum intensity projection display, which is the most conventional method for displaying a simple 3D image of the MR angiogram, makes it difficult to visualize depth information [ 1 ].
In addition, this method is not capable of separating each anatomical structure. However, the original CT and MR data can be manipulated to provide the surgeon with greater volume, anatomical and flow information.
There is a need to use the data from these new imaging modalities more efficiently. Our approach is to use a surface rendering 3D reconstruction method using MR angiogram or MR images [ 7 , 8 , 9 ]. There are several advantages to this compared to current radiological techniques. First, the examination is less invasive than cerebral angiography or DSA. Second, each 3D object can be made translucent, removed, rotated with a mouse-controlled cursor, and lesions can be observed from various directions.
The viewer can easily understand the morphology of complicated structures or get a "surgeon's eye view" before the operation. Third, the velocity encoding allows identification of arteries and veins [ 11 ]. Thus allows us to differentiate feeding arteries and draining veins in the axial MRI. The MR data is used during surgical resection of an AVM when differentiating arteries and veins which grossly appear similar.
Therefore, optimized data acquisition and appropriate image processing can provide useful information for cerebrovascular disease treatment.