The preoperative grading of gliomas, which is critical for guiding therapeutic strategies, remains unsatisfactory. We aimed to retrospectively assess the efficacy of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) in the grading of gliomas. Forty-two newly diagnosed glioma patients underwent conventional MR imaging, DWI, and contrast-enhanced MR imaging. Parameters of apparent diffusion coefficient (ADC), slow diffusion coefficient (D), fast diffusion coefficient (D*), and fraction of fast ADC (f) were generated. They were tested for differences between low- and high-grade gliomas based on one-way ANOVA. Receiver-operating characteristic (ROC) analyses were conducted to determine the optimal thresholds as well as the sensitivity and specificity for grading. ADC, D, and f were higher in the low-grade gliomas, whereas D* tended to be lower (all P<0.05). The AUC, sensitivity, specificity and the cutoff value, respectively, for differentiating low- from high-grade gliomas for ADC, D and f, and differentiating high- from low-grade gliomas for D* were as follows: ADC, 0.926, 100%, 82.8%, and 0.7 × 10−3 mm2/sec; D, 0.942, 92.3%, 86.2%, and 0.623 × 10−3 mm2/sec; f, 0.902, 92.3%, 86.2%, and 35.3%; D*, 0.798, 79.3%, 84.6%, and 0.303 × 10−3 mm2/sec. The IVIM DWI demonstrates efficacy in differentiating the low- from high-grade gliomas.

Early therapeutic effects of anti-angiogenic agent ZD6474 upon nasopharyngeal carcinoma (NPC) in nude mouse were monitored by using intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI). Mice bearing NPC underwent IVIM DWI at baseline and after 1, 3, and 7 days of treatment with ZD6474 or vehicle (n = 12 per group). Parameters of apparent diffusion coefficient (ADC), true diffusion coefficient (D), perfusion fraction (f), and blood pseudodiffusion coefficient (D*) at different time points were compared between the two groups or within the treated group. In the treated group, the perfusion-related parameters f and D* of the tumors decreased significantly on day 1 while the diffusion-related parameters ADC and D were significantly higher beginning on day 3 compared with the control group. The decreases in f on day 1 and D* on day 3 were moderately correlated with the smaller tumor size change on day 7. Moderate correlations were established between MVD and f and D* as well as between increased TUNEL or decreased Ki-67 index and ADC and D. This study supports that IVIM DWI is sensitive to detect the ZD6474-induced changes in NPC in nude mouse and the f parameter could predict early response to anti-angiogenic treatment.

Multimodal magnetic resonance (MR) imaging, including MR angiography (MRA) and MR perfusion (MRP), plays a critical role in the diagnosis and surveillance of acute ischemic stroke. However, these techniques are hindered by the low T1 relaxivity, short circulation time, and high leakage rate from vessels of clinical Magnevist. To address these problems, nontoxic polyethylene glycol (PEG)ylated upconversion nanoprobes (PEG-UCNPs) are synthesized and first adopted for excellent MRA and MRP imaging, featuring high diagnostic sensitivity toward acute ischemic stroke in high-resolution imaging. The investigations show that the agent possesses superior advantages over clinical Magnevist, such as much higher relaxivity, longer circulation time, and lower leakage rate, which guarantee much better imaging efficiency. Remarkably, an extremely small dosage (5 mg Gd kg(-1) ) of PEG-UCNPs provides high-resolution MRA imaging with the vascular system delineated much clearer than the Magnevist with clinical dosage as high as 108 mg Gd kg(-1) . On the other hand, the long circulation time of PEG-UCNPs enables the surveillance of the progression of ischemic stroke using MRA or MRP. Once translated, these PEG-UCNPs are expected to be a promising candidate for substituting the clinical Magnevist in MRA and MRP, which will significantly lengthen the imaging time window and improve the overall diagnostic efficiency.

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Purpose: To quantitatively analyze the shape of eyes with high myopia and provide assistance for posterior scleral reinforcement (PSR) using high-resolution three-dimensional (3D) magnetic resonance imaging (MRI). Method: In all, 260 eyes of 134 patients with high myopia were assessed in this study; 120 emmetropic volunteers were enrolled as a control group. The subjects were examined using 3D T2-weighted CUBE sequences. Results: The eyeballs' axial, horizontal, and vertical lengths were longer and their volume was larger in the subjects with high myopia than in those with emmetropia. The sites of the four recti and optic nerve attachment to the eye were clearly seen on 3D MRI, and the geometric information could be quantified for PSR preparation. The scleral strip was revealed by 3D MRI after surgery. Conclusions: 3D MRI can quantitatively analyze the shape of eyes with high myopia. 3D MRI examination might be necessary before and after PSR for preoperative preparation and postoperative assessment.

We evaluated the performance of intravoxel incoherent motion (IVIM) parameters for preoperatively predicting the subtype and Masaoka stage of thymic epithelial tumors (TETs). Seventy-seven patients with pathologically confirmed TETs underwent a diffusion weighted imaging (DWI) sequence with 9 b values. Differences in the slow diffusion coefficient (D), fast perfusion coefficient (D), and perfusion fraction (f) IVIM parameters, as well as the multi b-value fitted apparent diffusion coefficient (ADCmb), were compared among patients with low-risk (LRT) and high-risk thymomas (HRT) and thymic carcinomas (TC), and between early stage (stages I and II) and advanced stage (stages III and IV) TET patients. ADCmb, D, and D values were higher in the LRT group than in the HRT or TC group, but did not differ between the HRT and TC groups. The mean ADCmb, D, and D values were higher in the early stage TETs group than the advanced stage TETs group. The f values did not differ among the groups. These results suggest that IVIM DWI could be used to preoperatively predict subtype and Masaoka stage in TET patients.

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BackgroundA number of studies have demonstrated the significant and rapid antidepressant effects of ketamine, which is also known as a neurotoxic and illicit drug. Ketamine and alcohol are increasingly used together in clubs by teenagers and young adults. Previous studies have proven that chronic ketamine consumption induces a delayed and persistent activation of the dopamine (DA) system. However, the rewarding properties of recreational ketamine abuse remain unclear, and the underlying mechanisms of the effects on the DA system after administration of ketamine with ethanol are yet to be explored.MethodsHere, we evaluated the effects of two different doses of ketamine (30 mg/kg and 60 mg/kg) with and without ethanol (0.3156 g/kg) on DA concentration in the rat’s ventral tegmental area (VTA), a vital region in the reward and motivation system. We explored the effects of the combined drug treatment on the expression profiling of the DA metabolism genes, tyrosine hydroxylase, dopa decarboxylase, vesicular monoamine transporter 2, and synaptosomal-associated protein 25, as well as protein expression level of brain-derived neurotrophic factor in the rat’s VTA.ResultsWe found that administration of ketamine with ethanol led to a significant increase of DA in the VTA associated with differential regulation of mRNA levels of the four DA metabolism genes and protein levels of brain-derived neurotrophic factor. Moreover, the rewarding properties of coadministration of ketamine and ethanol were related to dopaminergic neuron activation in the VTA.ConclusionThese results indicated the possibility that combined drug treatment might positively affect the mesencephalic DA reward system.