Realistic Virtual Endoscopy of the ventricle system and haptic-based surgical simulator of hydrocefalus treatment.

New methods and software tools for automatic extraction of the ventricle system from magnetic resonance imagery (MRI) data, ventricle part classification, and realistic texturing are proposed to support Virtual Endoscopy (VE). Volume- and surface-based medical atlases are intensively used as templates in the methods. The processed ventricle-related surfaces are then utilized in a haptic-based system, which provides a surgeon with several basic functions simulating "virtual treatment" of hydrocephalus.

[High uptake of N-isopropyl-p-[123I]-iodoamphetamine (123I-IMP) demonstrated by dynamic SPECT in some cases of glioma].

Selective high uptake of N-isopropyl-p-[123I]-iodoamphetamine (123I-IMP) in the brain tumors is not common, the mechanism of uptake in the brain tumor is not yet clearly understood. Among 26 cases of gliomas investigated by dynamic SPECT, 4 cases including 2 cases of anaplastic astrocytoma and 2 cases of oligodendroglioma, showed high uptake of 123I-IMP. New three detector type camera which enables us to investigate rapid successive scanning, was used in our study. In dynamic SPECT, 15 successive scans of 2 minutes interval were made for 30 minutes after administration of 123I-IMP. In addition, quick dynamic SPECT was tried in 2 cases, in which 10 quick successive scans of 24 seconds interval were investigated for initial 4 minutes immediately after administration of 123I-IMP. Radioactivity in the region of interest inside the tumor (T) and radioactivity of the corresponding site in the contralateral hemisphere (C) was measured respectively, and T/C ratio was calculated. Time course change of radioactivity (time activity curve: TAC) was analyzed in all cases. Radioactivity was always higher in the tumor and the average T/C ratio was 1.40. TAC showed rapid increase of 123I-IMP in the tumor during initial 2 minutes after administration and keeping its high plateau level for 30 minutes. Angiography in these cases revealed a remarkable tumor stain. On the other hand, these gliomas showed no or slight enhancement effect in CT or MRI. These findings are interpretable as that early high uptake of 123I-IMP in some gliomas is attributable to an increased vascular bed and blood flow with no or minimal derangement of blood brain barrier in these tumors.

[Changes of regional perfusion in metastatic brain tumor and peritumoral area after radiosurgery: a study by 123I-IMP dynamic SPECT].

Changes of regional perfusion in the tumor, peritumoral edematous area and juxtatumor brain after radiosurgical treatment for metastatic brain tumor were investigated by dynamic SPECT using 123I-IMP. The SPECT was performed in 12 patients before and 1, 7 and 30 days after stereotactic irradiation. A region of interest (ROI) was selected each in the tumor, peritumoral edematous area, juxtatumor brain and ipsilateral cerebellum. Radioactivity in each ROIs was counted on early SPECT based on dynamic SPECT from 0 to 5 minutes. Mean count/pixel in each ROIs was divited by mean count/pixel in the ROI of the ipsilateral cerebellum and its value was designated as a count ratio (CR). Assuming the pre-treatment CRs are 1.0, relative changes of post-treatment CRs investigated. rCR in the tumor did not show any significant change after radiosurgical treatment. rCR in the edematous area and the juxtatumor brain increased at 7 days after irradiation [Mean +/- SD 1.43 +/- 0.409 (p < 0.05), 1.248 +/- 0.228 (p < 0.05) by Mann-Whitney test] and at 30 days [1.359 +/- 0.245 (p < 0.01), 1.301 +/- 0.287 (p < 0.01)] respectively. Computed tomography revealed no change in the maximum diameter of the tumor at 1 month after irradiation but a significant reduction in the diameter [0.744 +/- 0.227 (p < 0.02)] at 2 months. Early improvement of regional cerebral blood flow in the juxtatumor areas after radiosurgery suggested that radiosurgery could be effective treatment for metastatic brain tumor.