Purpose. Improving the efficiency of CT in the differential diagnosis of mass-forming pancreatitis (MFP) and pancreatic ductal adenocarcinoma (PDAC) making a diagnostic model based using a combination of texture features and contrast enhancement features.Methods and materials. 45 patients with histologically confirmed non-metastatic locally advanced PDAC and 13 patients with MFP where underwent CT examination with contrast enhancement. For each group, the ratio of the densities of intact pancreatic tissue and tumors, the relative tumor enhancement ratio (RTE) in all enhanced phases of CT, 94 texture features for each phase of the study were calculated and compared. The selection of predictors in the logistic model was carried out in 2 stages: 1) selection of predictors based on one-factor logistic models, the selection criterion was padj <0.2; 2) selection of predictors using LASSO-regression after standardization of variables. The selected predictors were included in a logistic regression model without interactions.Results. There were statistically significant differences in 14, 17, 4 out of 94 for the unenhanced, arterial, and venous phases of the study, respectively (p < 0.05). After selection, the final diagnostic model included the texture features CONVENTIONAL HUQ2 and DISCRETIZED HUQ1 for the unenhanced phase, DISCRETIZED HUQ1 and GLRLM RLNU for the arterial phase, DISCRETIZED Skewness for the venous phase, RTE for the delayed CT phase. The diagnostic model was built showed an accuracy of 81% in the diagnosis of MFP.Conclusion. We have developed a diagnostic model, including textural parameters and contrast enhancement features, which allows preoperatively distinguish MFP and PDAC, the developed model will increase the accuracy of preoperative diagnosis.
Purpose. Comparison of computer tomography (СT) contrast enhancement (CE) protocols for optimal visualization of cardiac chamber, definition it’s influence on results of non-invasive superficial cardiac mapping.Materials and methods. The study included 93 patients with heart rhythm disorders who planned catheter ablation of arrhythmia. Noninvasive cardiac mapping was made for topical diagnostics. It includes multichannel ECG-registration and CT with intravenous СE (1st group monophasic (50 patients), 2nd group split-bolus (18 patients), 3rd group with pre-bolus (25 patients). Qualitative and quantitative (measurement of mean blood attenuation in four chambers, calculation of ventricular-myocardial contrast-to-noise ratio VM-LV и VM-RV for left ventricle (LV) and right ventricle (RV), respectively) parameters were compared between groups. Fusion of ECG and CT data was made semi-automatic with diagnostic complex «Amycard 01К».Results. Regardless of CE technique was noted sufficient and homogeneous contrast attenuation of left atrium (LA) and LV (mean blood attenuation in LA more than 278 HU, LV 250 HU, VM-LV 0,582). Enhancement of right heart was insufficient with monophasic protocol, in most cases the average CT density was lower than 200 HU, VM-RV 0,256. Split-bolus protocol improves visualization of right atrium (RA) and RV (blood density in RA 258HU, RV 227HU, VM-RV 0,541), however there was heterogeneity of RA cavity because of artifacts from superior vena cava (VC) and unenhanced blood from inferior inferior VC. Using of pre-bolus increases contrast ratio between RA myocardium and blood due to increasing CT density of blood in inferior VC (blood density 294 HU). Quality of right ventricle CE was similar to 2nd group (blood density 264 HU, VM-RV 0,565).Conclusion. CE protocols split-bolus and with pre-bolus improve visualization of right ventricle, supporting the high level enhancement of left heart. Protocol with pre-bolus is preferable for exact differentiation of right atrial endocardial contour.
To demonstrate the possible difficulties in the diagnosis of hepatic echinococcosis, that a specialist in ultrasound diagnostics and a radiologist may encounter in everyday practice, russian and foreign literature as well as our own experience have been reviewed. With high accuracy and specificity of ultrasonography in the differential diagnosis of echinococcal cysts, incorrect interpretation is possible in the presence of mural hemorrhages and (or) hemorrhagic clots in a nonparasitic cyst, which aren’t also visible in ultrasonography and can imitate elements of the chitinous membrane. The degree of prevalence of the process, the exclusion of damage to the lungs and other organs of the abdominal cavity are important. In such cases CT scan is the most convenient and accurate diagnostic method due to its high spatial and temporal resolution, standardization and availability. In the most difficult cases the capabilities of MRI are used in the comparison of diffusion-weighted images and apparent diffusion coefficient, which also makes it possible to diagnose cystic neoplasms. Ultrasonography is a diagnostic technology that is still the most commonly used to differentiate cavity structures; however, all dubious clinical observations should be further examined by using CT or MRI.
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