Visualization Of Brain Tumors Research Articles

Clinical Application of 7.0 T Magnetic Resonance Images in Gamma Knife Radiosurgery for a Patient with Brain Metastases

In the study we assessed the distortion of 7.0 T magnetic resonance (MR) images in reference to 1.5 T MR images in the radiosurgery of metastatic brain tumors. Radiosurgery with Gamma Knife Perfexion® was performed for the treatment of a 54-yr-old female patient with multiple brain metastases by the co-registered images of the 7.0 T and 1.5 T magnetic resonance images (MRI). There was no significant discrepancy in the positions of anterior and posterior commissures as well as the locations of four metastatic brain tumors in the co-registered images between 7.0 T and 1.5 T MRI with better visualization of the anatomical details in 7.0 T MR images. This study demonstrates for the first time that 7.0 T MR images can be safely utilized in Perfexion® Gamma Knife radiosurgery for the treatment of metastatic brain tumors. Furthermore 7.0 T MR images provide better visualization of brain tumors without image distortion in comparison to 1.5 T MR images.

High-resolution brain tumor visualization using three-dimensional x-ray phase contrast tomography

We report on significant advances and new results concerning a recently developed method for grating-based hard x-ray phase tomography. We demonstrate how the soft tissue sensitivity of the technique is increased and show in vitro tomographic images of a tumor bearing rat brain sample, without use of contrast agents. In particular, we observe that the brain tumor and the white and gray brain matter structure in a rat's cerebellum are clearly resolved. The results are potentially interesting from a clinical point of view, since a similar approach using three transmission gratings can be implemented with more readily available x-ray sources, such as standard x-ray tubes. Moreover, the results open the way to in vivo experiments in the near future.

Intérêt de la TEP au [ 18F]-FDG double phase avec acquisition tardive dans la détection des tumeurs cérébrales

The value of FDG-PET remains controversial in the study of brain tumors because of the high FDG uptake in gray matter. The aim of this study was to evaluate the utility of 18FDG-PET delayed acquisitions in the distinction of brain tumors from the cortex. Thirty patients with cerebral tumors were included, 25 high-grade tumors and five low grade. Two FDG-PET acquisitions, early (1 h), and delayed (5 h), were performed. On the delayed images, two types of three-dimensional regions of interest (ROI) were drawn using a Bayesian segmentation based on a Poisson law, the lesion ROI, specific (LS) and total (LT), and the ROI of references, on the healthy hemicortex (SG) and on the healthy white matter (SB). These ROI were reported on the early images. The evolution of the visualization of the lesions was appreciated using a qualitative visual analysis and a ROI ratios analysis. On the delayed images, the visual and the ROI ratios analysis showed an improvement of the visualization of the hypermetabolic specific lesions compared to the SG and the SB. There was also a contrast improvement between the hypometabolic specific lesions and the SG with the ROI ratios analysis. Conclusion: delayed acquisitions in FDG-PET improve the visualization of brain tumors from the cortex. Dual phase FDG-PET with delayed acquisition could constitute an additional tool in the management of brain tumors.

Evaluation of Primary Brain Tumors With FLT-PET: Usefulness and Limitations

The purpose of this report was to investigate the potential of positron emission tomography using F-18 fluorodeoxythymidine (FLT-PET) in evaluating primary brain tumors. FLT-PET was performed in 25 patients with primary brain tumors. FLT uptake in the lesion was semiquantitatively evaluated by measuring the maximal standardized uptake value (SUVmax) and the tumor-to-normal tissue ratio (TNR). SUVmax and TNR were compared with the histologic grade and the expression of the proliferation marker (Ki-67). FLT uptake in normal brain parenchyma was very low, resulting in the visualization of brain tumors with high contrast. Both SUVmax and TNR significantly correlated with the malignant grade of brain gliomas, in which high SUVmax/TNR was obtained for high-grade gliomas. Patients with primary lymphoma also showed SUVmax/TNR equivalent to glioblastoma. There was a positive correlation between SUVmax/TNR and the Ki-67 index. In contrast, spuriously high SUVmax and TNR were obtained in 3 of 6 patients with suspected recurrent tumors (2 patients with recurrent grade 2 glioma and one patient with postoperative granuloma), all of which showed lesion enhancement on MRI after Gd administration. FLT-PET can be used to evaluate the malignant grade and proliferation activity of primary brain tumors, especially malignant brain tumors. However, the presence of benign lesions showing blood-brain barrier disruption cannot be distinguished from malignant tumors and needs to be carefully evaluated.

Microvessel density is not crucial for scintigraphic visualization of brain tumors using 99mTc-MIBI

Functional imaging of brain tumors assists biopsy localization, therapy monitoring, and differentiating tumor recurrence from radiation necrosis. Tumor vascularization is a strong prognostic predictor in solid tumors and also a key factor of tracer uptake. However, the relationship of brain tumor vascularization and functional imaging has not yet been investigated sufficiently so far. In the present study, we correlated histologically assessed microvessel density as an objective parameter for brain tumor vascularization with imaging data. Four male patients were studied. After 99mTc-MIBI scintigraphy, all patients had a MRI within 2 weeks. Histology showed microcystic astrocytoma, glioblastoma ( n = 2), and anaplastic oligodendroglioma, respectively. Microvessel density was lowest in the microcystic astrocytoma, medium in the glioblastomas, and highest in the anaplastic oligodendroglioma. Scintigraphy visualized only the glioblastomas, but not the microcystic astrocytoma or oligodendroglioma. Our data showed no correlation between tumor microvessel density and 99mTc-MIBI scintigraphy. Thus, we conclude that scintigraphic visualization of brain tumors is not strictly dependent on tumor vascularization.

Magnetic Resonance Imaging of Pediatric Brain Tumors

When done with care, the visualization of brain tumors in children in most cases is easy. The challenge is in ability to predict tumor type and grade. Slightly less than half of pediatric brain tumors are in the posterior fossa. Astrocytomas, medulloblastomas, and ependymomas account for 95% of these tumors. Except for the large cysts and uniformly low T1 signal of pilocytic cerebellar astrocytomas, location and size are more important than specific imaging characteristics in predicting tumor type. Supratentorial tumors are even more variable in magnetic resonance imaging characteristics, and it is difficult to tell benign from malignant tumor in many cases. Although gadolinium enhancement is useful in defining tumor borders, it is not a completely reliable indicator of malignancy. As in the posterior fossa, location is important in deciding which type of tumor is more likely. Suprasellar tumors are usually craniopharyngiomas. Small temporal lobe tumors are often oligodendrogliomas or gangliogliomas. Astrocytomas are the most common tumor, and also variable, although most benign astrocytomas are near the midline.