Multimodal MR imaging (diffusion, perfusion, and spectroscopy): is it possible to distinguish oligodendroglial tumor grade and 1p/19q codeletion in the pretherapeutic diagnosis?

BACKGROUND AND PURPOSE: Pretherapeutic determination of tumor grade and genotype in grade II and III oligodendroglial tumors is clinically important but is still challenging. Tumor grade and 1p/19q status are currently the 2 most important factors in therapeutic decision making for patients with these tumors. Histopathology and cMRI studies are still limited in some cases. In the present study, we were interested in determining whether the combination of PWI, DWI, and MR spectroscopy could help distinguish oligodendroglial tumors according to their histopathologic grade and genotype. MATERIALS AND METHODS: We retrospectively reviewed 50 adult patients with grade II and III oligodendrogliomas and oligoastrocytomas who had DWI, PWI, and MR spectroscopy at short and long TE data and known 1p/19q status. Univariate analyses and multivariate random forest models were performed to determine which criteria could differentiate between grades and genotypes. RESULTS: ADC, rCBV, rCBF, and rK2 were significantly different between grade II and III oligodendroglial tumors. DWI, PWI, and MR spectroscopy showed no significant difference between tumors with and without 1p/19q loss. Separation between tumor grades and genotypes with cMRI alone showed 31% and 48% misclassification rates, respectively. Multimodal MR imaging helps to determine tumor grade and 1p/19q genotype more accurately (misclassification rates of 17% and 40%, respectively). CONCLUSIONS: Although multimodal investigation of oligodendroglial tumors has a lower contribution to 1p/19q genotyping compared with cMRI alone, it greatly improves the accuracy of grading of these neoplasms. Use of multimodal MR imaging could thus provide valuable information that may assist clinicians in patient preoperative management and treatment decision making.

Grafting and polymer formation on silicon from unsaturated Grignards: II. Aliphatic precursors.

Anodic decomposition of a vinylmagnesium halide or an ethynylmagnesium halide at a surface-hydrogenated silicon electrode leads to the formation of polymeric layers covalently anchored to the silicon surface. These layers have been characterized using spectroellipsometry and photoluminescence, infrared, and X-ray photoelectron spectroscopy. In the case of vinyl precursors, it appears that the multiple bonds are largely broken in the process. In the case of ethynyl, the layer formation rate is much higher for the chloride than for the bromide. The obtained polymer appears as a saturated skeleton bearing halide and unsaturated ethynyl groups. Furthermore, it appears that the solvent may be attacked by the ethynyl radicals leading to contamination of the polymer by solvent fragments, an effect that can largely be avoided by using appropriate solvents. The reaction pathways are discussed.

Grafting and polymer formation on silicon from unsaturated Grignards: I-aromatic precursors.

Anodic decomposition of a phenylmagnesium halide at a surface-hydrogenated silicon electrode leads to formation of polymeric layers covalently anchored to the silicon surface. These layers have been characterized using spectroellipsometry, photoluminescence, infrared, and X-ray photoelectron spectroscopies. The phenyl ring appears preserved in the process, and the polymer formed is a polyphenylene. Contamination by aliphatic groups from the solvent may be minimized by using a solvent resistant to hydrogen abstraction by the phenyl radicals. Regioselectivity of the branching may be oriented to the para form by using 4-chlorophenylmagnesium bromide as the precursor.

Monoclonal antibodies to axolotl immunoglobulins specific for different heavy chains isotypes expressed by independent lymphocyte subpopulations.

An immunoblotting analysis of purified axolotl immunoglobulins (Ig) separated by SDS-PAGE reveals two heavy (H) chains isotypes: a 76 kDA chain recognized by the monoclonal antibody (mAb) 33.45.1 and a 66-68 kDa doublet recognized by the mAb 33.39.2. The 76 kDa chain is associated to high molecular weight (HMW) Ig molecules and the 66-68 kDa H chains are associated to low molecular weight (LMW) Ig of 172 kDa. Both H chains isotypes are linked to identical light (L) chains, labelled in immunoblotting by the mAb 33.101.2. Two different axolotl lymphocyte subpopulations are characterized by these two distinct H chains isotypes. One population of splenic lymphocytes (approximately 40%) is labeled by indirect immunofluorescence with mAb 33.45.1, specific for the 76 kDa H chain isotype. Another population (approximately 20%) is labeled by mAb 33.39.2 specific for the 66-68 kDa H chain isotype. Both populations of splenic lymphocytes are stained by mAb 33.101.2 specific for the axolotl L chains. Therefore, the presence of at least two independent Ig classes is now confirmed in a urodele amphibian species at the humoral and cellular levels.