Wei-Min Chai

Correlation of iron in the hippocampus with MMSE in patients with Alzheimer's disease

To investigate the brain iron deposits in patients with Alzheimers disease (AD) and healthy age‐matched controls using phase imaging.

Breast Cancer: Diffusion Kurtosis MR Imaging—Diagnostic Accuracy and Correlation with Clinical-Pathologic Factors

PURPOSE To assess diagnostic accuracy with diffusion kurtosis imaging (DKI) in patients with breast lesions and to evaluate the potential association between DKI-derived parameters and breast cancer clinical-pathologic factors. MATERIALS AND METHODS Institutional review board approval and written informed consent were obtained. Data from 97 patients (mean age ± standard deviation, 45.7 years ± 13.1; range, 19-70 years) with 98 lesions (57 malignant and 41 benign) who were treated between January 2014 and April 2014 were retrospectively analyzed. DKI (with b values of 0-2800 sec/mm(2)) and conventional diffusion-weighted imaging data were acquired. Kurtosis and diffusion coefficients from DKI and apparent diffusion coefficients from diffusion-weighted imaging were measured by two radiologists. Student t test, Wilcoxon signed-rank test, Jonckheere-Terpstra test, receiver operating characteristic curves, and Spearman correlation were used for statistical analysis. RESULTS Kurtosis coefficients were significantly higher in the malignant lesions than in the benign lesions (1.05 ± 0.22 vs 0.65 ± 0.11, respectively; P < .0001). Diffusivity and apparent diffusion coefficients in the malignant lesions were significantly lower than those in the benign lesions (1.13 ± 0.27 vs 1.97 ± 0.33 and 1.02 ± 0.18 vs 1.48 ± 0.33, respectively; P < .0001). Significantly higher specificity for differentiation of malignant from benign lesions was shown with the use of kurtosis and diffusivity coefficients than with the use of apparent diffusion coefficients (83% [34 of 41] and 83% [34 of 41] vs 76% [31 of 41], respectively; P < .0001) with equal sensitivity (95% [54 of 57]). In patients with invasive breast cancer, kurtosis was positively correlated with tumor histologic grade (r = 0.75) and expression of the Ki-67 protein (r = 0.55). Diffusivity was negatively correlated with tumor histologic grades (r = -0.44) and Ki-67 expression (r = -0.46). CONCLUSION DKI showed higher specificity than did conventional diffusion-weighted imaging for assessment of benign and malignant breast lesions. Patients with grade 3 breast cancer or tumors with high expression of Ki-67 were associated with higher kurtosis and lower diffusivity coefficients; however, this association must be confirmed in prospective studies.

Diffusion Tensor Imaging Correlates with Proton Magnetic Resonance Spectroscopy in Posterior Cingulate Region of Patients with Alzheimer’s Disease

Background/Aims: To compare proton magnetic resonance spectroscopy (1H-MRS) and diffusion tensor imaging (DTI) findings in the posterior cingulate regions in patients with Alzheimer’s disease (AD). Methods: 17 patients with mild AD, 20 with moderate to severe AD and 20 cognitively normal aging subjects (CN) underwent single-voxel MRS and DTI examinations. A region of interest was positioned in the posterior cingulate regions. Ratios of N-acetylaspartate (NAA), myo-inositol (mI), and choline to creatine (Cr) were measured. Mean spectroscopy data and DTI values (fractional anisotropy, FA, and mean diffusivity, MD) were analyzed with nonparametric testing. Results: The group with mild AD showed a significantly lower FA value in the left posterior cingulum compared to CN. The group with moderate to severe AD revealed significantly decreased FA values and increased MD values in both the left and right cingulum compared to the group with mild AD. Partial correlation analysis revealed a positive correlation between mI/Cr and left-side FA values in the group with mild AD and a negative correlation between NAA/Cr and right-side MD values in the group with moderate to severe AD. Conclusion: There are different regional and temporal patterns in AD, resulting from gliosis or axonal loss. Combining MRS with DTI could provide valuable information to better understand the AD process.

Microbubble-based synchrotron radiation phase contrast imaging: basic study and angiography applications

The purpose of the study was to evaluate the feasibility of microbubbles as phase contrast imaging (PCI) agents for angiography applications. The hypothesis was that the introduction of microbubbles into tissue produces a significant change in the refractive index and highlights the lumen of the vessel in PCI. The absorption and phase contrast images of commercially available microbubbles were obtained and compared in vitro. A further increase in contrast was observed in PCI. Microbubbles highlighted the lumen of the renal microvessels, acting as a positive contrast medium in ex vivo imaging. In addition, home-made microbubbles with larger diameters were introduced for image contrast enhancement in living tumor-bearing mice, demonstrating the feasibility of microbubble-based x-ray phase-contrast imaging for tumor vasculature in vivo.

Anti-VEGFR2-conjugated PLGA microspheres as an x-ray phase contrast agent for assessing the VEGFR2 expression.

The primary goal of this study was to evaluate the feasibility of using anti-vascular endothelial growth factor receptor 2 (VEGFR2)-conjugated poly(lactic-co-glycolic acid) (PLGA) microspheres as an x-ray phase contrast agent to assess the VEGFR2 expression in cell cultures. The cell lines, mouse LLC (Lewis lung carcinoma) and HUVEC (human umbilical vein endothelial cell), were selected for cell adhesion studies. The bound PLGA microspheres were found to better adhere to LLC cells or HUVECs than unbound ones. Absorption and phase contrast images of PLGA microspheres were acquired and compared in vitro. Phase contrast imaging (PCI) greatly improves the detection of the microspheres as compared to absorption contrast imaging. The cells incubated with PLGA microspheres were imaged by PCI, which provided clear 3D visualization of the beads, indicating the feasibility of using PLGA microspheres as a contrast agent for phase contrast CT. In addition, the microspheres could be clearly distinguished from the wall of the vessel on phase contrast CT images. Therefore, the approach holds promise for assessing the VEGFR2 expression on endothelial cells of tumor-associated vessels. We conclude that PLGA microsphere-based PCI of the VEGFR2 expression might be a novel, promising biomarker for future studies of tumor angiogenesis.

Three-dimensional Contrast-enhanced Ultrasound in Response Assessment for Breast Cancer: A Comparison with Dynamic Contrast-enhanced Magnetic Resonance Imaging and Pathology

To compare the capabilities of three-dimensional contrast enhanced ultrasound (3D-CEUS) and dynamic contrast-enhanced magnetic resonance (DCE-MRI) in predicting the response to neoadjuvant chemotherapy (NAC) among breast cancer patients, 48 patients with unilateral breast cancer were recruited for 3D-CEUS and DCE-MRI examinations both before and after NAC; pathology was used to validate the results. This study was approved by the institutional review board, and written informed consent was obtained from each patient. Imaging feature changes and pathological vascularity response, including microvessel density (MVD) and vascular endothelial growth factor (VEGF), were calculated. Pathological complete response (pCR) and major histological response (MHR) were used as references. The 3D-CEUS score, DCE-MRI score, MVD and VEGF significantly decreased (P < 0.0001) after NAC. The correlations between Δ3D-CEUS and ΔDCE-MRI with pCR (r = 0.649, P < 0.0001; r = 0.639, P < 0.0001) and MHR (r = 0.863, P < 0.0001; r = 0.836, P < 0.0001) were significant. All scores showed significant differences between the pCR and non-pCR groups with folder changes of 0.1, 0.1, 2.4, and 2.3, respectively (P = 0.0001, <0.0001, <0.0001 and <0.0001). In conclusion, 3D-CEUS is effective in assessing the response of breast cancer patients undergoing NAC.

CO2-based in-line phase contrast imaging of small intestine in mice

The objective of this study was to explore the potential of CO2 single contrast in-line phase contrast imaging (PCI) for pre-clinical small intestine investigation. The absorption and phase contrast images of CO2 gas production were attained and compared. A further increase in image contrast was observed in PCI. Compared with CO2-based absorption contrast imaging (ACI), CO2-based PCI significantly enhanced the detection of mucosal microstructures, such as pits and folds. The CO2-based PCI could provide sufficient image contrast for clearly showing the intestinal mucosa in living mice without using barium. We concluded that CO2-based PCI might be a novel and promising imaging method for future studies of gastrointestinal disorders.

In-Line Phase Contrast Imaging of Hepatic Portal Vein Embolization with Radiolucent Embolic Agents in Mice: A Preliminary Study

It is crucial to understand the distribution of embolic agents inside target liver during and after the hepatic portal vein embolization (PVE) procedure. For a long time, the problem has not been well solved due to the radiolucency of embolic agents and the resolution limitation of conventional radiography. In this study, we first reported use of fluorescent carboxyl microspheres (FCM) as radiolucent embolic agents for embolizing hepatic portal veins. The fluorescent characteristic of FCM could help to determine their approximate location easily. Additionally, the microspheres were found to be fairly good embolizing agents for PVE. After the livers were excised and fixed, they were imaged by in-line phase contrast imaging (PCI), which greatly improved the detection of the radiolucent embolic agents as compared to absorption contrast imaging (ACI). The preliminary study has for the first time shown that PCI has great potential in the pre-clinical investigation of PVE with radiolucent embolic agents.

A Rim-Enhanced Mass with Central Cystic Changes on MR Imaging: How to Distinguish Breast Cancer from Inflammatory Breast Diseases?

Objective To evaluate the capacity of magnetic resonance imaging (MRI) to distinguish breast cancer from inflammatory breast diseases manifesting as a rim-enhanced mass with central cystic changes. Materials and Methods Forty cases of breast cancer and 52 of inflammatory breast diseases showing a rim-enhanced mass with central cystic changes were retrospectively reviewed. All cases underwent dynamic contrast-enhanced MRI and 31 of them underwent diffusion-weighted imaging (DWI). Morphological features, dynamic parameters and apparent diffusion coefficient (ADC) values were comparatively analyzed using univariate analysis and binary logistic regression analysis. Results Breast cancer had a significantly thicker wall than the inflammatory breast diseases (P<0.001) while internal enhancing septa were more common in inflammatory breast diseases (P = 0.003). On DWI, 86.7% of breast cancers demonstrate a peripheral hyperintensity whereas 93.8% of inflammatory breast diseases had a central hyperintensity (P<0.001). Compared to the inflammatory breast diseases, breast cancers had a lower ADC value for the wall (1.09×10−3 mm2/s vs 1.42×10−3 mm2/s, P<0.001) and a higher ADC value for the central part (1.94×10−3 mm2/s vs 1.05×10−3 mm2/s, P<0.001). Conclusions Both breast cancer and inflammatory breast diseases could present as a rim-enhanced mass with central cystic changes on MRI. Integrated analysis of the MR findings can allow for an accurate differential diagnosis.

X-ray Phase Contrast Imaging of Cell Isolation with Super-Paramagnetic Microbeads

Super-paramagnetic microbeads are widely used for cell isolation. Evaluation of the binding affinity of microbeads to cells using optical microscopy has been limited by its small scope. Here, magnetic property of microbeads was first investigated by using synchrotron radiation (SR) in-line x-ray phase contrast imaging (PCI). The cell line mouse LLC (Lewis lung carcinoma) was selected for cell adhesion studies. Targeted microbeads were prepared by attaching anti-VEGFR2 (vascular endothelial growth factor receptor-2) antibody to the shell of the microbeads. The bound microbeads were found to better adhere to LLC cells than unbound ones. PCI dynamically and clearly showed the magnetization and demagnetization of microbeads in PE-50 tube. The cells incubated with different types of microbeads were imaged by PCI, which provided clear and real-time visualization of the cell isolation. Therefore, PCI might be considered as a novel and efficient tool for further cell isolation studies.