BACKGROUND AND PURPOSE: PET/MR imaging is a relatively new hybrid technology that holds great promise for the evaluation of head and neck cancer. The aim of this study was to assess the performance of simultaneous PET/MR imaging versus MR imaging in the evaluation of posttreatment head and neck malignancies, as determined by its ability to predict locoregional recurrence or progression after imaging. MATERIALS AND METHODS:The electronic medical records of patients who had posttreatment PET/MR imaging studies were reviewed, and after applying the exclusion criteria, we retrospectively included 46 studies. PET/MR imaging studies were independently reviewed by 2 neuroradiologists, who recorded scores based on the Neck Imaging Reporting and Data System (using CT/PET-CT criteria) for the diagnostic MR imaging sequences alone and the combined PET/MR imaging. Treatment failure was determined with either biopsy pathology or initiation of new treatment. Statistical analyses including univariate association, interobserver agreement, and receiver operating characteristic analysis were performed. RESULTS:There was substantial interreader agreement among PET/MR imaging scores (k ¼ 0.634; 95% CI, 0.605-0.663). PET/MR imaging scores showed a strong association with treatment failure by univariate association analysis, with P , .001 for the primary site, neck lymph nodes, and combined sites. Receiver operating characteristic curves of PET/MR imaging scores versus treatment failure indicated statistically significant diagnostic accuracy (area under curve range, 0.864-0.987; P , .001).CONCLUSIONS: Simultaneous PET/MR imaging has excellent discriminatory performance for treatment outcomes of head and neck malignancy when the Neck Imaging Reporting and Data System is applied. PET/MR imaging could play an important role in surveillance imaging for head and neck cancer.
SIRT1 is a NAD-dependent histone deacetylase involved in the regulation of transcription, apoptosis, metabolism and differentiation. We have previously demonstrated that sublytic levels of complement C5b-9 terminal complex increased the survival of oligodendrocytes (OLGs) and induced their dedifferentiation. In this study we investigated the role of SIRT1 in OLGs differentiation and the effect of sublytic levels of C5b-9 on SIRT1 expression. We also investigated the downstream effects of SIRT1 by measuring histone H3 Lysine 9 trimethylation (H3K9me3) and expression of cyclin D1. OLG progenitor cells purified from the brain of rat pups were differentiated in vitro and stimulated with sublytic C5b-9 or C5b6 for 3, 6 and 18 h. The level of SIRT1 mRNA was measured using real-time PCR and SIRT1, cyclin D1 and H3K9me3 protein expression were measured using western blotting. We found a decreased expression of SIRT1 mRNA and protein, a decreased level of H3K9me3 and an increased expression of cyclin D1 during OLG differentiation. Stimulation of OLGs with sublytic C5b-9 for 3h resulted in a significant decrease in SIRT1 mRNA and protein levels while stimulation with C5b6 had no effect. SIRT1 protein level in OLGs after 8h of exposure to C5b-9 were significantly lower than in C5b6 treated cells. H3K9me3 levels also decreased significantly after stimulation with C5b-9 as compared with unstimulated or C5b6-treated OLGs. Cyclin D1 expression increased after stimulation with C5b-9, indicating cell cycle activation. Our data show that C5b-9 stimulation of OLGs reduces SIRT1 expression, contributing to cell cycle activation by decreasing repressive trimethylation of histone H3 lysine 9.
Background The etiology of idiopathic intracranial hypertension (IIH) is uncertain. Studies suggest the fundamental cause of the Chiari 1 malformation, a congenitally hypoplastic posterior fossa, may explain the genesis of IIH in some patients. Purpose To assess the hypothesis that linear and volumetric measurements of the posterior fossa (PF) can be used as predictors of IIH. Material and Methods A retrospective analysis of magnetic resonance imaging (MRI) studies on 27 patients with IIH and 14 matched controls was performed. A volumetric sagittal magnetization prepared rapid acquisition gradient echo sequence was used to derive 10 linear cephalometric measurements. Total intracranial and bony posterior fossa volumes (PFVs) were derived by manual segmentation. The ratio of PFV to total intracranial volume was calculated. Results In total, 41 participants were included, all women. Participants with IIH had higher median body mass index (BMI). No significant differences in linear cephalometric measurements, total intracranial volumes, and PFVs between the groups were identified. Linear measurements were not predictive of volumetric measurements. However, on multivariate logistic regression analysis, the likelihood of IIH decreased significantly per unit increase in relative PFV (odds ratio [OR]=3.66 × 10−50; 95% confidence interval [CI]=1.39 × 10−108 to 1.22 × 10−5; P = 0.04). Conversely, the likelihood of IIH increased per unit BMI increase (OR=1.19; 95% CI=1.04–1.47; P = 0.02). Conclusion MRI-based volumetric measurements imply that PF alterations may be partly responsible for the development of IIH and Chiari 1 malformations. Symptoms of IIH may arise due to an interplay between these and metabolic, hormonal, or other factors.
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