Taking advantages of the sparsity or compressibility inherent in real world signals, compressed sensing (CS) can collect compressed data at the sampling rate much lower than that needed in Shannon’s theorem. The combination of CS and low rank modeling is used to medical imaging techniques to increase the scanning speed of cardiac magnetic resonance (CMR), alleviate the patients’ suffering and improve the images quality. The alternating direction method of multipliers (ADMM) algorithm is proposed for multiscale low rank matrix decomposition of CMR images. The algorithm performance is evaluated quantitatively by the peak signal to noise ratio (PSNR) and relative l2 norm error (RLNE), with the human visual system and the local region magnification as the qualitative comparison. Compared to L + S, kt FOCUSS, k-t SPARSE SENSE algorithms, experimental results demonstrate that the proposed algorithm can achieve the best performance indices, and maintain the most detail features and edge contours. The proposed algorithm can encourage the development of fast imaging techniques, and improve the diagnoses values of CMR in clinical applications.
Objective To summary the recent progression of imaging methods which mainly applied on the early detection and qualitative diagnosis of pancreatic cancer. Method The newest related literatures between home and abroad were collected and reviewed. Results Ultrasonic, computed tomography, magnetic resonance imaging and positron emission tomography mostly be used on pancreatic cancer detection and diagnosis. Conclusion Each method gets its own advantage even computed tomography seems like dominated on the detection and diagnosis pancreatic cancer, moreover, magnetic resonance imaging has been improved rapidly in recent years which shows its enormous potential.
Objective To explore the differential diagnosis significance of 3.0T MRI united-sequences examination in the diagnosis of benign and malignant breast lesions. Methods A total of 67 breast lesions of 59 patients were collected prospectively, which be treated at the Sichuan Provincial People’s Hospital during July 2015 to January 2017. All patients were underwent bilateral breast 3.0T magnetic resonance plain scan, diffusion weighted imaging, and dynamic enhanced scan successively before surgical operation. Analysis of morphological features of the benign and malignant breast lesions, the time-signal intensity curve (TIC), the apparent diffusion coefficient (ADC), and the combination diagnosis of them were performed. Results Of all 59 patients, 67 lesions were confirmed by histopathology, including 18 benign lesions and 49 malignant lesions. The morphological features (including margin, shape, border, and evenness), the types of TIC of dynamic enhancement, and ADC value between the benign lesions and malignant lesions were statistically significant (P<0.05). The sensitivity and specificity of Fischer scoring system was 89.8% (44/49) and 61.1% (11/18) respectively. The sensitivity and specificity of TIC types was 83.7% (41/49) and 77.8% (14/18) respectively. The diagnostic threshold of ADC value was 1.012×10–3 mm2/s, with the sensitivity and specificity for the diagnosis was 91.8% (45/49) and 83.3% (15/18) respectively. The sensitivity and specificity of the combination of Fischer scoring system and TIC type for diagnosis between benign and malignant breast lesions was 95.9% (47/49) and 72.2% (13/18) respectively. The sensitivity and specificity of the combination of Fischer scoring system, TIC type, and ADC value for benign and malignant breast lesions was 98.0% (48/49) and 83.3% (15/18) respectively. Conclusion The combination of Fischer scoring system, TIC type, and diffusion-weighted imaging for the differential diagnosis between benign lesions and malignant lesions was more effective than single imaging method.
Objective To clarify relationship between signal heterogeneity on hepatobiliary phase of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI and prognosis of hepatocellular carcinoma (HCC). Methods From January 2014 to January 2017 in the First Affiliated Hospital of Chongqing Medical University, a total of 77 patients with the pathologically proved HCC underwent Gd-EOB-DTPA-enhanced MRI prior to surgery were included in this study. On the basis of the signal heterogeneity in the hepatobiliary phase, the included patients were designed to homogeneous hypointensity group and heterogeneous hyperintensity group. The disease-free survival time were compared between the 2 groups and it’s influencing factors were analyzed. Results Seventy-seven patients with HCC were included, including 45 cases of homogeneous hypointensity and 32 cases of heterogeneous hyperintensity. There were no significant differences in the age, gender, etiology, liver function, alpha-fetoprotein, differentiated degree, Child-Pugh grade, lesion diameter, lesion border, and number of lesions between the 2 groups (P>0.05). However, the HCC patients with heterogeneous hyperintensity had a later BCLC staging (P=0.001). The disease-free survival time of the patients with homogeneous hypointensity and heterogeneous hyperintensity was (17.0±9.8) months and (12.4±10.4)months, respectively. The Kaplan-Meier survival curve showed that the disease-free survival time in the patients with homogeneous hypointensity was significantly better than that in the patients with heterogeneous hyperintensity (P=0.020). The results of univariate analysis showed that the other confounding factors had no effect on the disease-free survival time of patients with hepatocellular carcinoma (P>0.05) except for the signal of hepatobiliary phase (P<0.05). Furthermore, the hepatobiliary phase signal, BCLC stage, and degree of differentiation, which might be clinically considered as potentially influencing for the prognosis of patients with HCC, were included in the Cox multivariate proportional hazard regression model and found that the heterogeneous hyperintensity was still the risk factor of the disease-free survival rate in patients with HCC (P=0.047). Conclusion Signal heterogeneity on hepatobiliary phase of Gd-EOB-DTPA-enhanced MRI is related to prognosis of patients with HCC, heterogeneous hyperintensity may indicate a lower disease-free survival rate.
ObjectiveTo investigate the changes and clinical significance of cardiac structure and function evaluation by cardiac magnetic resonance imaging (CMR) for patients with pectus excavatum deformity at preoperation. MethodsWe retrospectively analyzed 54 patients (24 children and 30 adults) who underwent pectus excavatum surgery from June 2012 to June 2014. There were 48 males and 6 females at age of 7-33 (19.08±5.17) years. All the patients underwent CMR using 1.5 Tesla scanner for evaluation of compressing and displacement of the heart. The major and minor dimensions of right ventricle were measured. The right ventricle end-diastole volume (RVEDV), right ventricle end-systolic volume (RVESV), and right ventricle ejection fraction (RVEF) were also recorded and analyzed. ResultsThe heart compression and displacement occurred in 83.3% of the children group and 90.0% of the adults group. The extent of heart displacement in the adults was more serious than that in the children (76.86%±13.30% vs. 67.99%±8.15%, P<0.05). The structure of right ventricle were striking distorted because right atrum or right ventricule below valve ring was compressed locally, with the major dimension of right ventricle obviously increased, and the minor dimension of right ventricle obviously decreased. The indices of right ventricle major dimension and right ventricle minor dimension were 61.14±0.44 mm/m2 and 14.82±2.52 mm/m2 in the children, 49.54±15.40 mm/m2 and 18.90 ±3.14 mm/m2 in the adults. The RVEDV and RVESV were significantly higher in the adults than those in the children (139.09±29.08 ml vs. 121.50±31.27 ml; 73.61±16.05 ml vs. 64.92±19.28 ml; P<0.05). RVEF was similar between the children and the adults (45.29%±4.14% vs. 46.30±6.09%). The patients' symptoms disappeared after correction of pectus excavatum. ConclusionCMR is an useful method for evaluating right ventricular structure and functions in patients with cardiac compression and distortion by pectus excavatum before operation, which can bring strong indications for pectus excavatum repair surgery.
Objective To summarize the research status and progress of imaging diagnosis of periampullary carcinoma. Methods The literatures on imaging diagnosis of periampullary carcinoma were reviewed. Results At present, the commonly used imaging diagnosis methods for periampullary carcinoma mainly include ultrasound, CT, MRI, and endoscopic retrograde cholangiopancreatography. Some other new imaging techniques had also been applied in the diagnosis and evaluation of periampullary carcinoma. Conclusions Different imaging methods have their own advantages and disadvantages in the diagnosis of periampullary carcinoma. Therefore, the detection rate and diagnostic accuracy of periampullary carcinoma can be improved by rational selection of imaging techniques or combined application of multiple techniques.
Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) may provide more information in diagnosis of malignant tumor compared to conventional magnetic resonance imaging (MRI). Nowadays, in order to utilize the information expediently and efficiently, many researchers are aiming at the development of computer-aided diagnosis (CAD) of malignant tumor based on DCE-MRI. In this review, we survey the research in this field and summarize the literature in four parts, i.e. ① image preprocessing——noise reduction and image registration; ② region of interests (ROI) segmentation; ③ feature extraction——exploring the image characteristics by analyzing the ROI quantitatively; ④ tumor lesion recognition and classification——distinguishing and classifying tumor lesions by learning the features of ROI. We summarize the application of CAD techniques of DCE-MRI for cancer diagnosis and, finally, give some discussion on how to improve the efficiency of CAD in the future research.
Urokinase plasminogen activator receptor (uPAR) is a membrane protein which is attached to the cellular external membrane. The uPAR expression can be observed both in tumor cells and in tumor-associated stromal cells. Thus, in the present study, the human amino-terminal fragment (hATF), as a targeting element to uPAR, is used to conjugate to the surface of superparamagnetic iron nanoparticle (SPIO). Flowcytometry was used to examine the uPAR expression in different tumor cell lines. The specificity of hATF-SPIO was verified by Prussian blue stain and cell phantom test. The imaging properties of hATF-SPIO were confirmed in vivo magnetic resonance imaging (MRI) of uPAR-elevated colon tumor. Finally, the distribution of hATF-SPIO in tumor tissue was confirmed by pathological staining. Results showed that the three cells in which we screened, presented different expression characteristics, i.e., Hela cells strongly expressed uPAR, HT29 cells moderately expressed uPAR, but Lovo cells didn't express uPAR. In vitro, after incubating with Hela cells, hATF-SPIO could specifically combined to and be subsequently internalized by uPAR positive cells, which could be observed via Prussian blue staining. Meanwhile T2WI signal intensity of Hela cells, after incubation with targeted probe, significantly decreased, and otherwise no obvious changes in Lovo cells both by Prussian blue staining and MRI scans. In vivo, hATF-SPIO could be systematically delivered to HT29 xenograft and accumulated in the tumor tissue which was confirmed by Prussian Blue stain compared to Lovo xenografts. Twenty-four hours after injection of targeting probe, the signal intensity of HT29 xenografts was lower than Lovo ones which was statistically significant. This targeting nanoparticles enabled not only in vitro specifically combining to uPAR positive cells but also in vivo imaging of uPAR moderately elevated colon cancer lesions.
An adaptive inertia weight particle swarm algorithm is proposed in this study to solve the local optimal problem with the method of traditional particle swarm optimization in the process of estimating magnetic resonance (MR) image bias field. An indicator measuring the degree of premature convergence was designed for the defect of traditional particle swarm optimization algorithm. The inertia weight was adjusted adaptively based on this indicator to ensure particle swarm to be optimized globally and to avoid it from falling into local optimum. The Legendre polynomial was used to fit bias field, the polynomial parameters were optimized globally, and finally the bias field was estimated and corrected. Compared to those with the improved entropy minimum algorithm, the entropy of corrected image was smaller and the estimated bias field was more accurate in this study. Then the corrected image was segmented and the segmentation accuracy obtained in this research was 10% higher than that with improved entropy minimum algorithm. This algorithm can be applied to the correction of MR image bias field.
The patients with rectal cancer account for 50% or more of patients with colorectal cancer. The rectal magnetic resonance imaging (MRI) plays a pivotal role in clinical practice for evaluating the treatment baseline of tumors. The structured report of MRI serves as the foundation so as to promote homogenized, standardized, and normalized diagnosis and treatment of rectal cancer. We presented the MRI-based baseline evaluation structured reporting system for rectal cancer developed by West China Hospital of Sichuan University, aiming to advance the standardization and normalization of imaging reports for treatment baseline assessment in rectal cancer.