Automatic extraction of point cloud on cartilage surface of intraoperative knee using FPFH-PointNet / 解剖学报

Objective The navigation system of robot-assisted knee arthroplasty uses a laser scanner to acquire intraoperative cartilage point clouds and align them with the preoperative model for automatic non-contact space registration. The intraoperative patient knee lesion point cloud contains a large number of irrelevant background point clouds of muscles, tendons, ligaments and surgical instruments. Manual removal of irrelevant point clouds takes up surgery time due to human-computer interaction, so in this study we proposed a novel method for automatic extraction of point clouds from the knee cartilage surface for fast and accurate intraoperative registration. Methods Due to the lack of adequate description of cartilage surface and geometric local information, PointNet cannot extract cartilage point clouds with high precision. In this paper, a fast point feature histogram(FPFH)-PointNet method combined with fast point feature histogram was proposed, which effectively described the appearance of cartilage point cloud and achieved the automatic and efficient segmentation of cartilage point cloud. Results The point clouds of distal femoral cartilage of 10 cadaveric knee specimens and 1 human leg model were scanned from different directions as data sets. The accuracy of cartilage point cloud segmentation by PointNet and FPFH-PointNet were 0.94 ±0.003 and 0.98 ±0, and mean intersection over union(mIOU) were 0.83 ±0.015 and 0.93 ±0.005, respectively. Compared with PointNet, FPFH-PointNet improved accuracy and mIOU by 4% and 10% respectively, while the elapsed time was only about 1.37 s. Conclusion FPFH-PointNet can accurately and automatically extract the knee cartilage point cloud, which meets the performance requirement for intraoperative navigation.

Classification of glioma and solitary brain metastasis using magnetic resonance imaging radiomics feature / 解剖学报

Objective To analyze the difference of radiomics features between solitary brain metastasis and glioma using routine 3T TI, T2 and fluid attenuation inversion recovery (FLAIR) magnetic resonance imaging, to explore the significance of texture features constructed in different directions and angles in tumor regions in distinguishing the two kinds of tumors, and to explore a feasible method for high-precision classification of solitary brain metastases and gliomas. Methods Given the multimodal images of 43 patients with glioma and 45 age- and sex- matched patients with solitary brain metastasis, the gray level co-occurrence matrices of different angles of each slice were constructed from the transverse, coronal and sagittal directions of the tumor regions of these images, and the texture spatial relationship features (including contrast, correlation, energy and homogeneity) were calculated. Wilcoxon rank sum test was used to eliminate redundant features and select features with strong distinguishing ability. Finally, SVM linear kernel classifier was used to classify the selected features to achieve the identification of the two kinds of tumors. Results When classifying glioma and solitary brain metastasis, the precision, recall, Fl score and accuracy of multimodal and multidirectional combination features were 0.8857, 0.9114, 0.8944 and 0.8922, respectively. The area under the receiver operating characteristic curve obtained by linear kernel SVM classifier was 0. 9602. Totally 40 of the 45 patients with solitary brain metastases were correctly classified, and 39 of the 43 gliomas were correctly classified. Conclusion The multimodal and multi-directional combination features of tumor areas can be classified by linear kernel SVM classifier to distinguish gliomas from solitary brain metastases, which can be used as a second opinion to effectively assist doctors in making diagnosis.

Impact of hypoxia-inducible factor-1 on tumor invasion and metastasis in breast cancer / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate HIF-1α gene expression in human breast cancer cells and the role of HIF-1 in tumor metastasis and invasion.</p><p><b>METHODS</b>Human breast cancer cell lines were cultured under normoxic or hypoxic conditions. Western blot was used to evaluate the protein expression of HIF-1α, p-vimentin and α-tubulin. Small interfering RNA targeting HIF-1α was used to block the expression of HIF-1α in MDA-MB-231 and SK-BR-3 cell lines. Matrigel transwell and cell wound healing assays were used to detect the capability of cellular invasion and migration, respectively.</p><p><b>RESULTS</b>Under normoxic condition, all the cell lines tested showed a base-level of HIF-1α expression. The highest expression level of HIF-1α protein was obtained in the MDA-MB-231 cell line, which is also noticed to be highly invasive and migratory in behavior. HIF-1α siRNA was capable of blocking the protein expression of both HIF-1α and p-vimentin and in addition, the attenuated ability of invasion and migration.</p><p><b>CONCLUSION</b>Since HIF-1 is able to promote invasion and metastasis of tumor cells, which may be considered as a target in anti-cancer therapy.</p>

P2Y purinergic receptor activated PI-3K/Akt signaling pathway in regulation of growth and invasion of prostatic cancer / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate P2Y purinergic receptor activated PI-3K/Akt signaling pathway in the regulation of growth and invasion of prostate cancer in vitro.</p><p><b>METHODS</b>Western blot was used to detect phosphorylation of Akt (a downstream target molecule of PI-3K) by P2Y receptor agonist in 1E8 cells (a highly metastatic subclone derived from PC-3 prostatic cancer cell line). Cell counts, flow cytometry, Matrigel invasion assay, wound healing assay and gelatin zymography were used to detect changes of biological behaviors of 1E8 cells after P2Y receptor activation.</p><p><b>RESULTS</b>AMP-PNP, one non-hydrolysis ATP analogue and P2Y receptor agonist, induced significant phosphorylation of Akt in a time- and dose-dependent manner in IE8 cells. LY294002, a specific inhibitor of PI-3K, effectively blocked Akt phosphorylation induced by AMP-PNP. Continuous exposure to AMP-PNP induced significant growth inhibition of 1E8 cells (inhibition rate at 50.2% at the 8th day), and this inhibition was mainly due to an arrest at S phase of the cell cycle (the S phase fraction of AMP-PNP treated cells was 22.3% higher than that of the control). Application of LY294002 did not reverse the growth inhibition effect of AMP-PNP. Matrigel invasion assay showed that AMP-PNP stimulation increased invasive ability of 1E8 cells, and this effect was effectively blocked by LY294002. No significant changes in the activation of MMP-2 and MMP-9 were detected by gelatin zymography, although wound healing assay showed 21.2% increase in cell migration after AMP-PNP treatment.</p><p><b>CONCLUSIONS</b>PI-3K/Akt signaling pathway participates in P2Y receptor-stimulated prostate cancer invasion by enhancing cell motility, rather than up-regulating MMP-2 and MMP-9 activities. PI-3K signaling pathway plays an important role in prostate cancer proliferation, but is not involved in P2Y receptor mediated growth inhibition.</p>

Segmenting lung fields in serial chest radiographs using both population and patient-specific shape statistics / 中国医疗器械杂志

This paper presents a new deformable model using both population-based and patient-specific shape statistics to segment lung fields from serial chest radiographs. First, a modified scale-invariant feature transform (SIFT) local descriptor is used to characterize the image features in the vicinity of each pixel, so that the deformable model deforms in a way that seeks for the region with similar SIFT local descriptors; second, the deformable model is constrained by both population-based and patient-specific shape statistics. At first, population-based shape statistics plays an leading role when the number of serial images is small, and gradually, patient-specific shape statistics plays a more and more important role after a sufficient number of segmentation results on the same patient have been obtained. The proposed deformable model can adapt to the shape variability of different patients, and obtain more robust and accurate segmentation results.

An approach to adaptive stereo brain image's segmentation / 中国医疗器械杂志

This paper presents a new method for automatically segmenting brain parenchyma and cerebrospinal fluid in routine single-echo MR images. This method is based on the coupled Markov models. They can model intensity measurement at each voxel site to implement piecewise smoothness constraint, and at the same time, model discontinuities to control the interaction between each pair of the neighboring voxel. The method is to derive the maximum a posteriori estimate of the regions and the boundaries by using Bayesian inference and neighborhood constraints based on Markov random fields (MRFs) models. This method has the following desirable properties: (1) the brain image can be well classified into white matter, grey matter and cerebrospinal fluid (CSF), and (2) it has a better robustness to noise and intensity inhomogeneity.

Effects of benazepril on apoptosis in the kidney of diabetic rats / 药学学报

<p><b>AIM</b>To investigate the effects of angiotensin converting enzyme inhibitor (ACEI) on apoptosis and the expression of Fas and Fas-L in the kidney of diabetic rats.</p><p><b>METHODS</b>Uninephrectomized Spraque-Dawley rats were used to induce diabetes by intraperitoneal injection of streptozotocin (65 mg.kg-1). Benazepril (10 mg.kg-1) was given daily by gavage from the next day of the induction to diabetes for 12 weeks. Apoptosis was evaluated by means of terminal-deoxynucleotidyl transferase mediated d-UTP nick end labeling (TUNEL). Flow cytometry and immunohistochemistry were used to detect the expression of Fas and Fas-L.</p><p><b>RESULTS</b>Compared with those in the kidneys of control group, apoptotic cells were more in number and the expression of Fas and Fas-L was higher in the diabetic kidneys (P < 0.05). The number of apoptotic cells and the level of expression of Fas and Fas-L were reduced by benazepril treatment (P < 0.05).</p><p><b>CONCLUSION</b>Angiotensin converting enzyme inhibitor benazepril showed some renal protective effect on diabetic nephropathy, partly through inhibiting apoptosis by down-regulating Fas and Fas-L expression.</p>