Simple quantitative measurement based on DWI to objectively judge DWI-FLAIR mismatch in a canine stroke model

PURPOSEDiffusion-weighted imaging (DWI) - fluid attenuated inversion recovery (FLAIR) mismatch was proven useful to time the onset of wake-up stroke; however, identifying the status of FLAIR imaging has been mostly subjective. We aimed to evaluate the value of relative DWI signal intensity (rDWI), and relative apparent diffusion coefficient (rADC) in identifying the FLAIR status in the acute period.METHODSAutologous clot was used to embolize left middle cerebral artery in 20 dogs. Magnetic resonance imaging was performed 3–6 hours and 24 hours after embolization. DWI-FLAIR mismatch was defined as hyperintense signal detected on DWI, but not on FLAIR. The mean values of rDWI or rADC of FLAIR- and FLAIR+ lesions were compared and the critical cutoff values of rDWI and rADC for identifying the FLAIR status were determined.RESULTSStroke models were successfully established in all animals. DWI+ lesions were found in all 20 dogs from three hours, while FLAIR+ lesions were found in three, 11, 16, 19, and 20 dogs at five time points after embolization, respectively. The mean rDWI values were significantly different between FLAIR- and FLAIR+ lesions (P < 0.001), but rADC values were not (P = 0.73). Using rDWI=1.90 as the threshold value, excellent diagnostic efficacy was achieved (AUC, 0.88; sensitivity, 0.77; specificity, 0.88). However, rADC appeared not useful (AUC, 0.48; sensitivity, 0.52; specificity, 0.58) in identifying the FLAIR status.CONCLUSIONIn our embolic canine stroke model, rDWI was useful to identify FLAIR imaging status in the acute period, while rADC was not

Fluorescence Modified Chitosan-Coated Magnetic Nanoparticles for High-Efficient Cellular Imaging

Labeling of cells with nanoparticles for living detection is of interest to various biomedical applications. In this study, novel fluorescent/magnetic nanoparticles were prepared and used in high-efficient cellular imaging. The nanoparticles coated with the modified chitosan possessed a magnetic oxide core and a covalently attached fluorescent dye. We evaluated the feasibility and efficiency in labeling cancer cells (SMMC-7721) with the nanoparticles. The nanoparticles exhibited a high affinity to cells, which was demonstrated by flow cytometry and magnetic resonance imaging. The results showed that cell-labeling efficiency of the nanoparticles was dependent on the incubation time and nanoparticles’ concentration. The minimum detected number of labeled cells was around 104by using a clinical 1.5-T MRI imager. Fluorescence and transmission electron microscopy instruments were used to monitor the localization patterns of the magnetic nanoparticles in cells. These new magneto-fluorescent nanoagents have demonstrated the potential for future medical use

Learning and Memory Alterations Are Associated with Hippocampal N-acetylaspartate in a Rat Model of Depression as Measured by 1H-MRS

It is generally accepted that cognitive processes, such as learning and memory, are affected in depression. The present study used a rat model of depression, chronic unpredictable mild stress (CUMS), to determine whether hippocampal volume and neurochemical changes were involved in learning and memory alterations. A further aim was to determine whether these effects could be ameliorated by escitalopram treatment, as assessed with the non-invasive techniques of structural magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS). Our results demonstrated that CUMS had a dramatic influence on spatial cognitive performance in the Morris water maze task, and CUMS reduced the concentration of neuronal marker N-acetylaspartate (NAA) in the hippocampus. These effects could be significantly reversed by repeated administration of escitalopram. However, neither chronic stress nor escitalopram treatment influenced hippocampal volume. Of note, the learning and memory alterations of the rats were associated with right hippocampal NAA concentration. Our results indicate that in depression, NAA may be a more sensitive measure of cognitive function than hippocampal volume

A novel nomogram to predict lymph node metastasis in cT1 non-small-cell lung cancer based on PET/CT and peripheral blood cell parameters

Abstract Background Accurately evaluating the lymph node status preoperatively is critical in determining the appropriate treatment plan for non-small-cell lung cancer (NSCLC) patients. This study aimed to construct a novel nomogram to predict the probability of lymph node metastasis in clinical T1 stage patients based on non-invasive and easily accessible indicators. Methods From October 2019 to June 2022, the data of 84 consecutive cT1 NSCLC patients who had undergone PET/CT examination within 30 days before surgery were retrospectively collected. Univariate and multivariate logistic regression analyses were performed to identify the risk factors of lymph node metastasis. A nomogram based on these predictors was constructed. The area under the receiver operating characteristic (ROC) curve and the calibration curve was used for assessment. Besides, the model was confirmed by bootstrap resampling. Results Four predictors (tumor SUVmax value, lymph node SUVmax value, consolidation tumor ratio and platelet to lymphocyte ratio) were identified and entered into the nomogram. The model indicated certain discrimination, with an area under ROC curve of 0.921(95%CI 0.866–0.977). The calibration curve showed good concordance between the predicted and actual possibility of lymph node metastasis. Conclusions This nomogram was practical and effective in predicting lymph node metastasis for patients with cT1 NSCLC. It could provide treatment recommendations to clinicians

Cross-modal missing time-series imputation using dense spatio-temporal transformer nets

Due to irregular sampling or device failure, the data collected from sensor network has missing value, that is, missing time-series data occurs. To address this issue, many methods have been proposed to impute random or non-random missing data. However, the imputation accuracy of these methods are not accurate enough to be applied, especially in the case of complete data missing (CDM). Thus, we propose a cross-modal method to impute time-series missing data by dense spatio-temporal transformer nets (DSTTN). This model embeds spatial modal data into time-series data by stacked spatio-temporal transformer blocks and deployment of dense connections. It adopts cross-modal constraints, a graph Laplacian regularization term, to optimize model parameters. When the model is trained, it recovers missing data finally by an end-to-end imputation pipeline. Various baseline models are compared by sufficient experiments. Based on the experimental results, it is verified that DSTTN achieves state-of-the-art imputation performance in the cases of random and non-random missing. Especially, the proposed method provides a new solution to the CDM problem

A comparison of the biological effects of 125I seeds continuous low-dose-rate radiation and 60Co high-dose-rate gamma radiation on non-small cell lung cancer cells.

To compare the biological effects of 125I seeds continuous low-dose-rate (CLDR) radiation and 60Co γ-ray high-dose-rate (HDR) radiation on non-small cell lung cancer (NSCLC) cells.A549, H1299 and BEAS-2B cells were exposed to 125I seeds CLDR radiation or 60Co γ-ray HDR radiation. The survival fraction was determined using a colony-forming assay. The cell cycle progression and apoptosis were detected by flow cytometry (FCM). The expression of the apoptosis-related proteins caspase-3, cleaved-caspase-3, PARP, cleaved-PARP, BAX and Bcl-2 were detected by western blot assay.After irradiation with 125I seeds CLDR radiation, there was a lower survival fraction, more pronounced cell cycle arrest (G1 arrest and G2/M arrest in A549 and H1299 cells, respectively) and a higher apoptotic ratio for A549 and H1299 cells than after 60Co γ-ray HDR radiation. Moreover, western blot assays revealed that 125I seeds CLDR radiation remarkably up-regulated the expression of Bax, cleaved-caspase-3 and cleaved-PARP proteins and down-regulated the expression of Bcl-2 proteins in A549 and H1299 cells compared with 60Co γ-ray HDR radiation. However, there was little change in the apoptotic ratio and expression of apoptosis-related proteins in normal BEAS-2B cells receiving the same treatment.125I seeds CLDR radiation led to remarkable growth inhibition of A549 and H1299 cells compared with 60Co HDR γ-ray radiation; A549 cells were the most sensitive to radiation, followed by H1299 cells. In contrast, normal BEAS-2B cells were relatively radio-resistant. The imbalance of the Bcl-2/Bax ratio and the activation of caspase-3 and PARP proteins might play a key role in the anti-proliferative effects induced by 125I seeds CLDR radiation, although other possibilities have not been excluded and will be investigated in future studies

Fetal ocular development in the second trimester of pregnancy documented by 7.0 T postmortem Magnetic Resonance Imaging.

Few investigators have analyzed fetal ocular growth with Magnetic Resonance Imaging (MRI) of high magnetic strength. Our purpose is to obtain normative biometrics for fetal ocular development in the second trimester of pregnancy. Sixty specimens with a gestational age (GA) of 12-23 weeks were scanned using a 7.0 T MRI scanner. The linear interocular and binocular distances (IOD and BOD, respectively), globe diameter (GD) and lens diameter (LD) were measured on the transverse section of the largest diameter of the eyeballs. The three dimensional (3D) visualization model of the eyeball was reconstructed with Amira software. Then, the globe and lens volumes (GV and LV, respectively) were obtained. All the measurements were plotted as a function of GA. The fetal ocular structures in the second trimester of pregnancy could be clearly delineated on 7.0 T postmortem MRI images. All the linear measurements logarithmically increased with GA, while, the volumetric measurements linearly increased with GA. Postmortem MRI of high magnetic strength can clearly document fetal ocular growth in the second trimester of pregnancy. These quantitative data may be a valuable reference for the assessment of normal fetal eyeball development in clinical settings and may be considered a supplement to anatomical investigations