Wavelet Analysis of Cerebral Oxygenation Signal Measured by Near-Infrared Spectroscopy in Moyamoya Disease.

BACKGROUND: Spontaneous low-frequency oscillations (LFOs) have been widely studied in cerebrovascular disease, but little is known about their role in moyamoya disease (MMD). The objective of this study was to assess the value of spontaneous LFOs in MMD based on wavelet analysis of near-infrared spectroscopy signals. METHODS: Sixty-four consecutive idiopathic adult patients were prospectively enrolled. The regional tissue oxygenation index (TOI) obtained from continuous near-infrared spectroscopy signals. Five frequency intervals of spontaneous LFOs (I, 0.0095-0.02 Hz; II, 0.02-0.06 Hz; III, 0.06-0.15 Hz; IV, 0.15-0.40 Hz; and V, 0.40-2.00 Hz) were extracted based on wavelet analysis. The data were compared between the patients and healthy control groups. Clinical features, cognitive function, and disease progression of MMD were analyzed using TOI and frequency interval data. RESULTS: Compared with the healthy control group, patients with MMD had a higher cerebral TOI in both hemispheres. Based on wavelet analysis, the spontaneous LFO of TOI was found to be significantly lower for patients with MMD in frequency intervals II to IV than that for the controls. The spontaneous LFO of TOI is also related to the Suzuki stages in intervals II to IV, stroke in interval III, and cognitive impairment in intervals III to Ⅳ. CONCLUSIONS: There were significant differences in spontaneous LFO between patients with MMD and healthy controls. The change in spontaneous LFO in MMD is related to Suzuki stage, cerebral infarction, and cognitive impairment. This might be an effective method for evaluating the severity and monitoring the progression of MMD.

IB-LBM simulation on blood cell sorting with a micro-fence structure.

A size-based blood cell sorting model with a micro-fence structure is proposed in the frame of immersed boundary and lattice Boltzmann method (IB-LBM). The fluid dynamics is obtained by solving the discrete lattice Boltzmann equation, and the cells motion and deformation are handled by the immersed boundary method. A micro-fence consists of two parallel slope post rows which are adopted to separate red blood cells (RBCs) from white blood cells (WBCs), in which the cells to be separated are transported one after another by the flow into the passageway between the two post rows. Effected by the cross flow, RBCs are schemed to get through the pores of the nether post row since they are smaller and more deformable compared with WBCs. WBCs are required to move along the nether post row till they get out the micro-fence. Simulation results indicate that for a fix width of pores, the slope angle of the post row plays an important role in cell sorting. The cells mixture can not be separated properly in a small slope angle, while obvious blockages by WBCs will take place to disturb the continuous cell sorting in a big slope angle. As an optimal result, an adaptive slope angle is found to sort RBCs form WBCs correctly and continuously.

[The clinical detection of breast cancer by spectrum method].

Breast cancer is one of the most frequently encountered malignant tumors of women. Early detection can save lives successfully. A safe, effective detection method is needed. The detection of breast cancer based on the laser-tissue interactions is an international research focus. The prototype of the detection system in the authors' lab uses a 780 nm low frequency modulated laser to penetrate breast tissue. Two-dimensional scan is processed under the control of computer. A photomultiplier tube (PMT) is used to get the penetrated light and convert it to electrical signal. The signal of light intensity is sampled by the system and used to get the near infrared penetrating image of breast after data processing. In the present paper the signal processing method is discussed and the data processing results in the lab experiments are given. Clinical trials were carried out in the Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, using NIR (near infrared light) breast scanner developed by the authors' lab. The investigations were performed after approval by the ethic committee of Cancer Institute and Hospital, Chinese Academy of Medical Sciences. Written informed consent was obtained from each subject. None of the patients' names, initials, or hospital numbers was used in this paper. Fifty patients underwent the examination. Thirty four of them were malignant, and 13 were benign. The other 3 lacked pathology results. Analysis and comparison were executed to evaluate the result. NIR images, mammographs, and the ultrasound images were compared with both the pathology results and each other. The accuracy percentage of NIR image reaches 72.5%, which is between the accuracy percentage of ultrasound (77.50%) and that of mammography (71.88%). In this paper, the characteristics of different breast diseases were found in NIR images, which offers criterion for NIR diagnosis method in detail. The typical NIR images of different diseases, such as papillomatosis with local cancer and cancer, were shown. The clinical trial verified the validity of tumor diagnosis with the special absorption of NIR light by hemoglobin. Both the position and the benign/malignant property of tumor can be detected by NIR method. The improving aspects of the prototype were proposed. A new approach was put forward to the optical method.