Low-dose helical CT projection data restoration using noise estimation / 南方医科大学学报

OBJECTIVE@#To build a helical CT projection data restoration model at random low-dose levels.@*METHODS@#We used a noise estimation module to achieve noise estimation and obtained a low-dose projection noise variance map, which was used to guide projection data recovery by the projection data restoration module. A filtering back-projection algorithm (FBP) was finally used to reconstruct the images. The 3D wavelet group residual dense network (3DWGRDN) was adopted to build the network architecture of the noise estimation and projection data restoration module using asymmetric loss and total variational regularization. For validation of the model, 1/10 and 1/15 of normal dose helical CT images were restored using the proposed model and 3 other restoration models (IRLNet, REDCNN and MWResNet), and the results were visually and quantitatively compared.@*RESULTS@#Quantitative comparisons of the restored images showed that the proposed helical CT projection data restoration model increased the structural similarity index by 5.79% to 17.46% compared with the other restoration algorithms (P < 0.05). The image quality scores of the proposed method rated by clinical radiologists ranged from 7.19% to 17.38%, significantly higher than the other restoration algorithms (P < 0.05).@*CONCLUSION@#The proposed method can effectively suppress noises and reduce artifacts in the projection data at different low-dose levels while preserving the integrity of the edges and fine details of the reconstructed CT images.

An adaptive CT metal artifact reduction algorithm that combines projection interpolation and physical correction / 南方医科大学学报

OBJECTIVE@#To propose an adaptive weighted CT metal artifact reduce algorithm that combines projection interpolation and physical correction.@*METHODS@#A normalized metal projection interpolation algorithm was used to obtain the initial corrected projection data. A metal physical correction model was then introduced to obtain the physically corrected projection data. To verify the effectiveness of the method, we conducted experiments using simulation data and clinical data. For the simulation data, the quantitative indicators PSNR and SSIM were used for evaluation, while for the clinical data, the resultant images were evaluated by imaging experts to compare the artifact-reducing performance of different methods.@*RESULTS@#For the simulation data, the proposed method improved the PSNR value by at least 0.2 dB and resulted in the highest SSIM value among the methods for comparison. The experiment with the clinical data showed that the imaging experts gave the highest scores of 3.616±0.338 (in a 5-point scale) to the images processed using the proposed method, which had significant better artifact-reducing performance than the other methods (P < 0.001).@*CONCLUSION@#The metal artifact reduction algorithm proposed herein can effectively reduce metal artifacts while preserving the tissue structure information and reducing the generation of new artifacts.

A nonlocal spectral similarity-induced material decomposition method for noise reduction of dual-energy CT images / 南方医科大学学报

OBJECTIVE@#To propose a nonlocal spectral similarity-induced material decomposition network (NSSD-Net) to reduce the correlation noise in the low-dose spectral CT decomposed images.@*METHODS@#We first built a model-driven iterative decomposition model for dual-energy CT, optimized the objective function solving process using the iterative shrinking threshold algorithm (ISTA), and cast the ISTA decomposition model into the deep learning network. We then developed a novel cost function based on the nonlocal spectral similarity to constrain the training process. To validate the decomposition performance, we established a material decomposition dataset by real patient dual-energy CT data. The NSSD-Net was compared with two traditional model-driven material decomposition methods, one data-based material decomposition method and one data-model coupling-driven material decomposition supervised learning method.@*RESULTS@#The quantitative results showed that compared with the two traditional methods, the NSSD-Net method obtained the highest PNSR values (31.383 and 31.444) and SSIM values (0.970 and 0.963) and the lowest RMSE values (2.901 and 1.633). Compared with the datamodel coupling-driven supervised decomposition method, the NSSD-Net method obtained the highest SSIM values on water and bone decomposed results. The results of subjective image quality assessment by clinical experts showed that the NSSD-Net achieved the highest image quality assessment scores on water and bone basis material (8.625 and 8.250), showing significant differences from the other 4 decomposition methods (P < 0.001).@*CONCLUSION@#The proposed method can achieve high-precision material decomposition and avoid training data quality issues and model unexplainable issues.

Performance of low-dose CT image reconstruction for detecting intracerebral hemorrhage: selection of dose, algorithms and their combinations / 南方医科大学学报

OBJECTIVE@#To investigate the performance of different low-dose CT image reconstruction algorithms for detecting intracerebral hemorrhage.@*METHODS@#Low-dose CT imaging simulation was performed on CT images of intracerebral hemorrhage at 30%, 25% and 20% of normal dose level (defined as 100% dose). Seven algorithms were tested to reconstruct low-dose CT images for noise suppression, including filtered back projection algorithm (FBP), penalized weighted least squares-total variation (PWLS-TV), non-local mean filter (NLM), block matching 3D (BM3D), residual encoding-decoding convolutional neural network (REDCNN), the FBP convolutional neural network (FBPConvNet) and image restoration iterative residual convolutional network (IRLNet). A deep learning-based model (CNN-LSTM) was used to detect intracerebral hemorrhage on normal dose CT images and low-dose CT images reconstructed using the 7 algorithms. The performance of different reconstruction algorithms for detecting intracerebral hemorrhage was evaluated by comparing the results between normal dose CT images and low-dose CT images.@*RESULTS@#At different dose levels, the low-dose CT images reconstructed by FBP had accuracies of detecting intracerebral hemorrhage of 82.21%, 74.61% and 65.55% at 30%, 25% and 20% dose levels, respectively. At the same dose level (30% dose), the images reconstructed by FBP, PWLS-TV, NLM, BM3D, REDCNN, FBPConvNet and IRLNet algorithms had accuracies for detecting intracerebral hemorrhage of 82.21%, 86.80%, 89.37%, 81.43%, 90.05%, 90.72% and 93.51%, respectively. The images reconstructed by IRLNet at 30%, 25% and 20% dose levels had accuracies for detecting intracerebral hemorrhage of 93.51%, 93.51% and 93.06%, respectively.@*CONCLUSION@#The performance of reconstructed low-dose CT images for detecting intracerebral hemorrhage is significantly affected by both dose and reconstruction algorithms. In clinical practice, choosing appropriate dose level and reconstruction algorithm can greatly reduce the radiation dose and ensure the detection performance of CT imaging for intracerebral hemorrhage.

Influence of projection data correction on digital breast tomosynthesis imaging / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of detector performance during digital breast tomography (DBT) projection data acquisition on reconstructed image quality.</p><p><b>METHODS</b>With reference to the traditional detector data correction method and the specific data acquisition pattern in DBT imaging, we utilized dark field correction, light field and its gain correction for processing the projection data collected by the detector. The reconstructed images were evaluated using iterative reconstruction method based on total generalized variation (TGV).</p><p><b>RESULTS</b>In physical breast phantom experiment, the proposed method resulted in a reduced Heel effect caused by nonuniform photon number. The reconstructed DBT images after correction showed obviously improved image quality especially in the details with a low contrast.</p><p><b>CONCLUSION</b>The dark field correction, light field and its gain correction process for DBT image reconstruction can improve the image quality.</p>

Anatomical basis and clinical research of pelvic autonomic nerve preservation with laparoscopic radical resection for rectal cancer / 华中科技大学学报（医学）（英德文版）

The clinical effect of laparoscopic rectal cancer curative excision with pelvic autonomic nerve preservation (PANP) was investigated. This study evaluated the frequency of urinary and sexual dysfunction of 149 male patients with middle and low rectal cancer who underwent laparoscopic or open total mesorectal excision with pelvic autonomic nerve preservation (PANP) from March 2011 to March 2013. Eighty-four patients were subjected to laparoscopic surgery, and 65 to open surgery respectively. The patients were followed up for 12 months, interviewed, and administered a standardized questionnaire about postoperative functional outcomes and quality of life. In the laparoscopic group, 13 patients (18.37%) presented transitory postoperative urinary dysfunction, and were medically treated. So did 12 patients (21.82%) in open group. Sexual desire was maintained by 52.86%, un-ability to engage in intercourse by 47.15%, and un-ability to achieve orgasm and ejaculation by 34.29% of the patients in the laparoscopic group. Sexual desire was maintained by 56.36%, un-ability to engage in intercourse by 43.63%, and un-ability to achieve orgasm and ejaculation by 33.73% of the patients in the open group. No significant differences in urinary and sexual dysfunction between the laparoscopic and open rectal resection groups were observed (P>0.05). It was concluded that laparoscopic rectal cancer radical excision with PANP did not aggravate or improve sexual and urinary dysfunction.

Sinogram restoration for low-dose cerebral perfusion CT images / 南方医科大学学报

In clinical cerebral perfusion CT examination, repeated scanning the region of interest in the cine mode increases the radiation dose of the patients, while decreasing the radiation dose by lowering the scanning current results in poor image quality and affects the clinical diagnosis. We propose a penalized weighted least-square (PWLS) method for recovering the projection data to improve the quality of low-dose cerebral perfusion CT imaged. This method incorporates the statistical distribution characteristics of brain perfusion CT projection data and uses the statistical properties of the projection data for modeling. The PWLS method was used to recover the data, and the Gauss-Seidel (GS) method was employed for iterative solving. Adaptive weighting is introduced between the original projection data and the projection data after PWLS restoration. The experimental results on the clinical data demonstrated that the PWLS-based sinogram restoration method improved noise reduction and artifact suppression as compared with the conventional noise reduction methods, and better retained the edges and details to generate better cerebral perfusion maps.

Anatomical basis and clinical research of pelvic autonomic nerve preservation with laparoscopic radical resection for rectal cancer / 华中科技大学学报（医学）（英德文版）

The clinical effect of laparoscopic rectal cancer curative excision with pelvic autonomic nerve preservation (PANP) was investigated. This study evaluated the frequency of urinary and sexual dysfunction of 149 male patients with middle and low rectal cancer who underwent laparoscopic or open total mesorectal excision with pelvic autonomic nerve preservation (PANP) from March 2011 to March 2013. Eighty-four patients were subjected to laparoscopic surgery, and 65 to open surgery respectively. The patients were followed up for 12 months, interviewed, and administered a standardized questionnaire about postoperative functional outcomes and quality of life. In the laparoscopic group, 13 patients (18.37%) presented transitory postoperative urinary dysfunction, and were medically treated. So did 12 patients (21.82%) in open group. Sexual desire was maintained by 52.86%, un-ability to engage in intercourse by 47.15%, and un-ability to achieve orgasm and ejaculation by 34.29% of the patients in the laparoscopic group. Sexual desire was maintained by 56.36%, un-ability to engage in intercourse by 43.63%, and un-ability to achieve orgasm and ejaculation by 33.73% of the patients in the open group. No significant differences in urinary and sexual dysfunction between the laparoscopic and open rectal resection groups were observed (P>0.05). It was concluded that laparoscopic rectal cancer radical excision with PANP did not aggravate or improve sexual and urinary dysfunction.

Motion-compensated compressed sensing four-dimensional cone-beam CT reconstruction / 南方医科大学学报

Restriction by hardware caused the very low projection number at a single phase for 4-dimensional cone beam (4D-CBCT) CT imaging, and reconstruction using conventional reconstruction algorithms is thus constrained by serious streak artifacts and noises. To address this problem, we propose an approach to reconstructing 4D-CBCT images with multi-phase projections based on the assumption that the image at one phase can be viewed as the motion-compensated image at another phase. Specifically, we formulated a cost function using multi-phase projections to construct the fidelity term and the TV regularization method. For fidelity term construction, the projection data of the current phase and those at other phases were jointly used by reformulating the imaging model. The Gradient-Projection-Barzilai-Line search (GPBL) method was used to optimize the complex cost function. Physical phantom and patient data results showed that the proposed approach could effectively reduce the noise and artifacts, and the introduction of additional temporal correlation did not introduce new artifacts or motion blur.

The relationship between serum uric acid and percutaneous oxygen partial pressure in patients with type 2 diabetes / 中国糖尿病杂志

Objective To explorethe relationship between serum uric acid (SUA ) and transcutaneousoxygenpressure(TcPO2)inpatientswithT2DM.Methods 622hospitalizedpatients with T2DM were recruited and divided into high SUA (HUA) group and normal SUA (T2DM) group.The differences in TcPO2 (initial value ,stable value ,initial value‐stable value ,leg‐raising initial value and leg‐raising maximum value)were compared between two groups.The correlations between SUA and TcPO2 were evaluated. Results The levels of TcPO2 were lower in HUA group than in T2DM group [initial value:left (34.05 ± 13.17) vs (39.26 ± 15.82) ,right (34.71 ± 14.90) vs (40.15 ± 16.23);stable value:left (38.93 ± 12.23) vs(45.19 ± 13.40) ,right (39.98 ± 12.34) vs (45.90 ± 16.77) ,P<0.05]. Pearson correlation analysis showed that the SUA levels negatively related with the stable TcPO2 value of leftor right side ,and with the change between the initial value and the stable value of TcPO2 (P<0.05 or P<0.01). The multiple linear regression analysis showed that SUA level was the impact factorof the left TcPO2 stable value. Conclusion HUA may be one of the risk factors microcirculation disorder in T2DM patients.

Incorporation of TV regularization in deconvolution for partial volume correction in PET imaging / 南方医科大学学报

We propose a method using total variation (TV) regularization in deconvolution for partial volume correction in PET imaging. In the degraded image model, we used TV regularization procedure in Van Cittert (VC) and Richardson-Lucy (RL) deconvolution algorithms. These methods were tested in simulated NCAT images and images of NEMA NU4-2008 IQ phantom and tumor-bearing mouse scanned by Simens Invoen microPET. The simulated experiment and tumor-bearing mouse experiment showed that the algorithms using TV regularization provided superior qualitative and quantitative appearance compared with traditional VC and RL algorithms. When the mean intensity of the tumor increased by (10±1.8)%, the SD increase percentage was decreased from 49.98% to 14.26% and from 42.76% to 4.70%, suggesting the efficiency of the proposed algorithms for reducing PVEs in PET.

Changes in the physical growth of children aged 3 to 6 years in urban areas of Lanzhou from 2001 to 2010 / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To study changes in the physical growth of preschool children aged 3 to 6 yeas in urban areas of Lanzhou from 2001 to 2010.</p><p><b>METHODS</b>Stratified, randomized, cluster sampling was used to collect physical examination data on children from 35 private and public kindergartens located in different urban areas of Lanzhou in 2001, 2006, and 2010. Changes in physical growth were analyzed using body height, body weight and body mass index (BMI) as main indices. Growth retardation, underweight, overweight, emaciation and obesity were screened out using height for age (HAZ), weight for age (WAZ), and weight for height (WHZ) and changes from 2001 to 2010 were analyzed.</p><p><b>RESULTS</b>Body height, body weight and BMI increased from 2001 to 2010 in children at different ages (P<0.05). Body height and weight increased with age, while BMI decreased with age. Mean values of HAZ, WAZ, and WHZ increased over time, showing that prevalence rates of underweight, growth retardation, and emaciation decreased from 2001 to 2010 while those of overweight and obesity increased.</p><p><b>CONCLUSIONS</b>Changes in the physical growth of preschool children in urban areas of Lanzhou from 2001 to 2010 were obvious, with increases in body height and body weight. However, problems such as overweight and obesity emerged. In response, while malnutrition is being solved, attention should be paid to over-nutrition that has an adverse effect on physical growth.</p>

Gene mutation and clinical characteristics of a Chinese Uygur family with spinocerebellar ataxia type 12 / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the CAG trinucleotide repeat expansion and clinical characteristics of a Chinese Uygur family with spinocerebellar ataxia type 12 (SCA12) in Xinjiang Uygur Autonomous Region.</p><p><b>METHODS</b>In the Uygur SCA12 family, 6 patients and 54 "healthy" members were analyzed by polymerase chain reaction, agarose gel electrophoresis, recombinant DNA technology by T-Vector cloning and restriction enzyme digestion, and direct sequencing. The diagnosis of SCA12 was confirmed. The CAG trinucleotide expansion was also analyzed.</p><p><b>RESULTS</b>Six members in the family were diagnosed as SCA12 patients and 13 were presymptomatic. Five of them were successfully detected by sequencing. The CAG repeat numbers of 4 patients were 47, 51, 52 and 53, respectively, and 48 in the presymptomatic patient. We also observed that in the CAG repeat region there was replacement of single nucleotide C, A or G.</p><p><b>CONCLUSION</b>Forty-seven CAG repeats of SCA12 has been reported as the shortest known causative expanded alleles. The present study is the first report of the characteristics of SCA12 gene mutation in Chinese. It will provide basis for the accurate classification, disease etiology, treatment and prenatal diagnosis of this disease.</p>

Three-dimensional low-dose CT volume reconstruction based on non-local weights optimization and GPU acceleration / 南方医科大学学报

Concerns have been raised over x-ray radiation dose associated with repeated computed tomography (CT) scans for tumor surveillance and radiotherapy planning. In this paper, we present a low-dose CT image reconstruction method for improving low-dose CT image quality. The method proposed exploited rich redundancy information from previous normal-dose scan image for optimizing the non-local weights construction in the original non-local means (NLM)-based low-dose image reconstruction. The objective 3D low-dose volume and the previous 3D normal-dose volume were first registered to reduce the anatomic structural dissimilarity between the two datasets, and the optimized non-local weights were constructed based on the registered normal-dose volume. To increase the efficiency of this method, GPU was utilized to accelerate the implementation. The experimental results showed that this method obviously improved the image quality, as compared with the original NLM method, by suppressing the noise-induced artifacts and preserving the edge information.

Duloxetine versus placebo in the treatment of patients with diabetic neuropathic pain in China / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Duloxetine, a selective serotonin and noradrenaline reuptake inhibitor, has been shown to be effective in treatment of diabetic peripheral neuropathic pain and approved for the management of patients with diabetic peripheral neuropathic pain (DPNP) in the United States, European Union, and many other countries. This study assessed the efficacy and safety of duloxetine in Chinese patients with diabetic peripheral neuropathic pain.</p><p><b>METHODS</b>This double-blind, randomized, placebo-controlled, flexible-dose study treated adult patients with diabetic peripheral neuropathic pain and baseline Brief Pain Inventory (BPI) 24-hour average pain severity ratings ≥ 4 with duloxetine 60 mg to 120 mg once daily or placebo for 12 weeks. Dose adjustments of duloxetine or matching placebo were based upon investigator's judgment of clinical response. Change from baseline to endpoint in BPI average pain was the primary efficacy outcome. Secondary outcome measures included BPI-severity and -Interference, Patient Global Impression of Improvement, Clinical Global Impressions of Severity, EuroQol: 5 Dimensions, Athens Insomnia Scale, and safety measures.</p><p><b>RESULTS</b>Of 215 patients randomized, 88.4% and 82.1% of patients in placebo and duloxetine groups, respectively, completed the study. Mean change from baseline to endpoint in BPI average pain was not statistically different between the treatment groups (P = 0.124). Duloxetine- treated patients showed significantly greater pain reduction compared with those in placebo group at weeks 1, 2, and 4 (P = 0.004, P = 0.009, and P = 0.006, respectively), but not at weeks 8 (P = 0.125) and 12 (P = 0.107). Duloxetine-treated patients experienced statistically significant improvement in Patient Global Impression of Improvement, Clinical Global Impression of Severity, area under the curve for pain relief, BPI-severity pain right now, and BPI-interference walking ability. Patients treated with duloxetine 120 mg once daily showed significantly greater pain reduction on the Brief Pain Inventory average pain score relative to placebo. Duloxetine-treated patients reported nausea, somnolence, anorexia, and dysuria significantly more than placebo.</p><p><b>CONCLUSIONS</b>Although the primary study endpoint was not achieved, the overall observed response pattern suggests the efficacy of duloxetine in the treatment of Chinese patients with diabetic peripheral neuropathic pain. The safety profile for duloxetine is similar to that reported in other global trials.</p>

Mutation analysis of a Chinese family with spinocerebellar ataxia 7 / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To characterize the clinical phenotype and the gene mutation of the spinocerebellar ataxia 7 (SCA7) family.</p><p><b>METHODS</b>Two patients from a two generation Hui Chinese pedigree were detected by gene test. Polymerase chain reaction (PCR) for CAG trinucleotide repeats was performed for the SCA7 gene, and the fragments with expanded alleles were subcloned into the pGEM-T plasmids and sequenced.</p><p><b>RESULTS</b>Molecular analysis demonstrated the pathological expansions in the SCA7 gene, with 46 CAG repeats in the expanded allele of the proband's father. The 46 repeats expanded to 54 repeats in the proband with marked anticipation of approximately 22 years.</p><p><b>CONCLUSION</b>This family was the first SCA7 Hui Chinese family reported. Retinal degeneration is relatively unique to SCA7. The instability of the expanded triplet repeats accounts for the marked anticipation and the rate of progression of the disease.</p>

Sparse angular CT projection onto convex set reconstruction using nonlocal means iterative modification / 南方医科大学学报

Based on the fact that nonlocal means (NL-means) filtered image can likely produce an acceptable priori solution, we propose a sparse angular CT projection onto convex set (POCS) reconstruction using NL-means iterative modification. The new reconstruction scheme consists of two components, POCS and NL-means filter. In each phase of the sparse angular CT iterative reconstruction, we first used POCS algorithm to meet the identity and non-negativity of projection data, and then performed NL-means filter to the image obtained by POCS method for image quality improvement. Simulation experiments showed that the proposed POCS scheme can significantly improve the quality of sparse angular CT image by suppressing the noise and removing the streak-artifacts.

Improved weighted cross-correlation coefficient with a new kernel and its application in predicting T cell epitopes / 南方医科大学学报

We designed a weighted cross-correlation coefficient considering the "anchor" of the T cell epitopes, and used an evolutionary algorithm to search for an optimal weight vector. A SVM model with this new peptide similarity kernel was evaluated on a T-cell data set. The results demonstrated a good performance of this method.

Identification of ATXN3 intermedial allele associated with a disease phenotype in an SCA3 Han Chinese family / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the clinical manifestation and the mutation characteristics of intermedial allele associated with a disease phenotype of a Machado-Joseph disease (MJD) family.</p><p><b>METHODS</b>Polymerase chain reaction, capillary electrophoresis, molecular cloning and sequencing were performed to detect the ATXN3 gene in an spinocerebellar ataxia(SCA) family. The fragments of expanded alleles were subcloned into the pGEM-T plasmids and sequenced.</p><p><b>RESULTS</b>The expanded repeats at the MJD locus were confirmed by molecular technique. The proband had 43 CAG repeats at the MJD locus. He had two sons with 41 and 64 repeats in the expanded allele respectively.</p><p><b>CONCLUSION</b>A 43 CAG repeat allele was unstable upon inter-generational transmission. The change of the CAG repeat was bidirectional. This is the shortest expanded allele associated with a disease phenotype in the MJD gene reported to date. The identification of the MJD family has reduced the amplitude between the normal and expanded allele repeats.</p>

Cone-beam pseudo lambda tomography under FDK framework / 南方医科大学学报

The medical CT scanner is rapidly evolving from the fan-beam mode to the cone-beam geometry mode. In this paper, a new cone-beam pseudo Lambda tomography was proposed based on the Noo's fan beam super-short scan formula and FDK framework. The proposed pseudo-LT algorithm, which avoids the computation of any PI line and any differential operation, has a significant practical implementation, thus leading to the images with quality improvement and reduced artifacts. The results in the simulation studies confirm the observation that the new algorithm can improve the image resolution over the traditional algorithms with noise projection data.