Objective To explore the optimization and standardization of imaging parameters for 16-slice spiral CT angiography in intracranial and cervical arteries. Methods Sixty patients were randomly divided into three groups, and the automatic bolus tracking thresholds of 100, 150 and 180 HU in the descending aorta were used respectively. The CT values of artery and vein among three groups were compared. Other 40 patients were randomly divided into A and B group and underwent CTA with different slice thickness and pitch, and the difference in arterial display were compared. Results The carotid and intracranial arteries in all three groups were well displayed. No statistical difference was found in enhancement CT values of three points of common carotid artery and internal carotid artery among three groups (P>0.05), while the differences of CT values in same level vein among three groups were significant (P<0.05). There was no significant difference in the average score of display degree between group A and B. Conclusion Imaging parameters for 16-slice spiral CT angiography in intracranial and cervical arteries are recommended as follows:100 HU (threshold), 120 kV, 280 mA, 1.25 mm (thickness), 1.375:1 (pitch), 0.5 s/r and 16×0.625 mm (effective thickness).

Objective To assess the utility of single source-dual energy CT for distinguishing bladder cancer from hematoma. Methods We retrospectively identified 14 patients with postoperative or follow-up bladder hematoma who had undergone dual energy protocol (40-140 keV)scanning by single source-dual energy CT.The subjective scoring of tumor detection and image quality,the optimal monochrome images and iodine-water images were evaluated by two radiologists who didn’t know the results.The consistency of two observers was analyzed by Kappa test.Mann-Whitney U test was used to compare the difference between the two kinds of diseases and ROC curve was used to analyze the diagnostic efficiency.The statistical differences of image quality scoring among different images were obtained by using Mann-Whitney U test.Results The consistency of the two observers about scoring of lesion detection was good for all groups.There were statistical differences between two groups in non-enhanced phase and arterial phase of mixed-energy images,non-enhanced phase,arterial phase and delayed phase of optimal monochromatic images,and all phase of iodine-water images. The AUC of iodine-water images in the four phases (0.985,1.000,0.955,0.924,respectively)were all higher than that of polychrome unenhanced and arterial phase images (0.909,0.909).The diagnostic efficiency of arterial phase on iodine-water images was the highest.Sensitivity and specificity were both 100% when score was greater than 2.5.There was no statistical difference between two kinds of diseases on non-enhanced phase,delayed phases of mixed-energy or monochromatic images(P >0.05).There were no statistical differences in image quality scoring among the three groups with the same phases (P>0.05).Conclusion Optimal monochromatic images and iodine-water images of single source-dual energy CT are more effective than conventional CT in distinguishing bladder cancer from hematoma.

Objective To explore the feasibility of reducing radiation dose and iodine contrast medium in 70 kVp abdominal CTA imaging in low-body mass index (BMI;≤22 kg/m2) patients.Methods The 48 patients with suspected abdominal vascular diseases and low BMI (≤22 kg/m2) underwent abdominal CTA.All patients were divided into two groups according to tube voltage and contrast intake randomly.The parameters of group A (n=27) were contrast intake 300 mgI/kg,70 kVp,the conditions of group B (n=21) were contrast intake 500 mgI/kg,120 kVp,and the other conditions were the same in both groups.The image quality of right renal arterial images was evaluated by two observers simultaneously (5-scale).The consistency and difference between the two observers were analyzed.The CT values of abdominal aorta,celiac trunk,superior mesenteric artery,common hepatic artery,pancreatic artery and erector spinae,SD values of erector spinae on the level of right renal hilus were measured respectively in both groups.The CT values of abdominal aorta and its main branches,the CNR of abdominal aorta,the volume CT dose index (CTDIvol),dose-length product (DLP) and overall iodine intake in each group were compared.Results The scoring of right renal arterial images in both groups were 5.00 (1.00),the results showed a good consistency (Kappa=0.932,0.911).The CT values of abdominal aorta,superior mesenteric artery,common hepatic artery and pancreatic artery in group A were all more than those of in group B (all P＜0.05).The CNR of group A was higher than that of group B (P＜0.05).The CTDIvoland DLP in group A decreased by 73.36％ and 74.41％ compared with group B.The overall iodine intakes in group A and group B were (46.33±6.43)ml and (84.31±10.71)rnl,respectively.The overall iodine intake of group A decreased by 45.05％ compared with group B.Conclusion For patients with low BMI (≤22 kg/m2),a 70 kVp tube current abdominal CTA scanning can significantly increase the contrast of images of abdominal artery and its branches.Meanwhile,the radiation dose and overall iodine intake can obviously decrease.

BACKGROUND:In spectral CT imaging study, the selection of scanning parameters is considered by most researchers, but the effects of measuring position are often overlooked. Actual measurement found that different measurement location had significant impact on the result of the measurement. Through measurement and mathematical model of a large amount of data, we can correct the measurement results of different location. The results with real data alignment are higher. OBJECTIVE:To explore effects of different measuring positions on results in spectral CT imaging, and to optimize correction coefficients. METHODS:GE standard water phantom was applied to orderly obtain 5 combined scanning parameters with 552 groups of data. Size measurement method was divided into two measuring range:ROI1 and ROI2. We selected 10 points to measure CT value, including Center, North, South, West and East. The measurement data of ROI1 and ROI2 were classified and screened based on the same sequence. Mathematical modeling and probability statistics analysis were used to optimize correction coefficient, get calibration function and draw experimental simulation curve. RESULTS AND CONCLUSION:(1) Measuring methods of ROI1 were superior to the ROI2’s on water phantom in spectrum CT. (2) To different scanning sequences, the measuring results were different. To the same scanning sequences, the measurements for different positions on water phantom in spectrum CT had remarkable influence on the measuring results, which varied from points to points. (3) Through setting up mathematical modeling, using method of statistical analysis, we could get the correction function on different measuring positions. (4) Above results confirmed that compared with the theoretical model and the experimental data of spectral CT scanning parameters, the coefficients of position can be adjusted, which can optimize the measuring results.

Objective To assess the value of spectral CT imaging in distinguishing mass type colorectal adenocarcinoma from colorectal adenoma. Methods Forty patients underwent preoperative abdominal dual energy spectral CT scan were analyzed restrospectively, including 17 with colorectal adenomas and 23 with mass type colorectal adenocarcinomas proven by endoscopic and surgical pathology. All patients underwent plain and three-phase enhanced CT scanning. The conventional polychromatic CT value and its pre- and postcontrast CT values, monochromatic CT value of 40 to 100 keV, the slope of spectral curve and iodine(water) concentration were measured, and the maximum diameter of the lesion was recorded. The maximum diameters of the lesions and imaging parameter differences between the adenomas and adenocarcinomas in plain and three-phase enhanced scan were analyzed with independent sample t tests. The data of the parameters with significant differences were further analyzed by ROC curves. Results The maximum diameters of the adenomas and mass type adenocarcinomas were (1.97 ± 0.54), (2.32±0.53) cm respectively, and there was no statistically significant difference (t=-2.011, P=0.051). There was no statistically differences of the conventional polychromatic CT value and its pre-and postcontrast CT values between the two groups in 4 phases (P>0.05). However, in the arterial phase, the CT values of adenomas were significantly lower than those of adenocarcinomas at low (40, 50 keV) energy (P<0.05). The values did not differ significantly between these two groups at other phases (P>0.05). The slope of spectral curve and the iodine(water) concentration both showed significant differences in the arterial phase between the two groups (P<0.05), while they were not significantly different at other phases (P>0.05).The largest area under the ROC curve of the iodine(water) concentration in the arterial phase was 0.757 in differentiating adenomas and mass type adenocarcinomas, with sensitivity of 73.9%and specificity of 82.4%at the cut-off of 21.02 mg/cm3. Conclusion Spectral CT imaging is valuable in differentiating colorectal adenoma from mass type colorectal adenocarcinoma with the parameters of the arterial phase.

Objective:To assess the value of amide proton transfer weighted (APTw) imaging in the evaluation of pH changes in infarct core (IC) and ischemic penumbra (IP) in subacute cerebral infarction.Methods:The data of twenty-three subacute cerebral infarction patients with unilateral steno-occlusive disease of the middle cerebral artery (subacute infarction group) from April to November 2019 in the First Affiliated Hospital of Dalian Medical University were prospectively analyzed. Fifteen healthy volunteers were enrolled in this study as the control group. All subjects underwent conventional MRI, DWI, 3D-pseudo continuous arterial spin labeling (3D-pCASL) and APTw sequences. Based on DWI images, relative cerebral blood flow (rCBF) and APTw images to determine the region of IC, blood flow penumbra [cerebral blood flow(CBF)-DWI mismatch area, IP CBF] and metabolic penumbra (APTw-DWI mismatched area, IP APT). 3D ROIs were used to semi-automatically measure the APTw signals and the volume of IC and IP CBF of the patients in subacute infarction group. The comparison of APTw signals between the infarct side and the contralateral side in the subacute infarction group, the comparison of bilateral APTw signals in the control group, and the comparison of APTw signals in the IC and IP CBF regions were performed by paired-sample t test or Wilcoxon signed-rank test. The paired-sample t test or Mann-Whitney U test was used to compare the APTw signals between the two groups. The Friedman test was applied to compare the difference of volumes among IP CBF1.5, IP CBF2.5 and IP APT . Results:There was no significant difference of the APTw signals among the IC, the contralateral side in the subacute infarction group and the control group ( P>0.05). The APTw signals of IP CBF and IC of the infarction group were statistically different ( P<0.05). Compared with the contralateral side of IP CBF1.5 (3.7±1.7, -1.84±1.48, 5.57±2.75), the APTwmax (3.07±1.41, t=-3.012, P=0.006), APTw min [-1.30 (-1.74, -0.57), Z=-2.099, P=0.036], and APTwmax-min(4.51±2.58, t=-3.273, P=0.003) signals in the IP CBF1.5 were decreased ( P<0.05). Compared with the contralateral side of IP CBF2.5 [-1.53 (-2.80, -0.91), 5.31±2.61], the APTw min [-1.08 (-1.60, -0.49), Z=-2.616, P=0.009] and APTwmax-min (4.41±2.72, t=-3.228, P=0.004) signals in the IP CBF2.5 were decreased. The volumes of IP CBF1.5 [107.51(50.08, 138.61)mm 3], IP APT [99.00 (53.27, 121.335) mm 3] and IP CBF2.5 [89.91 (51.53, 139.87) mm 3] were successively reduced (χ2=7.913, P=0.019), and the volume of IP CBF2.5 was significantly smaller than that of IP CBF1.5 ( P=0.037). Conclusion:The acid-base metabolism in the IC of subacute cerebral infarction is not obvious, but the blood flow penumbra has local acid-base metabolism imbalance, and the range of metabolic penumbra coincides with the blood flow penumbra.

OBJECTIVE: To exploit material decomposition analysis in dual-energy spectral computed tomography (CT) to assess the blood supply status of the ground-glass opacity (GGO) in lungs. MATERIALS AND METHODS: This retrospective study included 48 patients with lung adenocarcinoma, who underwent a contrast-enhanced dual-energy spectral CT scan before treatment (53 GGOs in total). The iodine concentration (IC) and water content (WC) of the GGO, the contralateral and ipsilateral normal lung tissues were measured in the arterial phase (AP) and their differences were analyzed. IC, normalized IC (NIC), and WC values were compared between the pure ground-glass opacity (pGGO) and the mixed ground-glass opacity (mGGO), and between the group of preinvasive lesions and the minimally invasive adenocarcinoma (MIA) and invasive adenocarcinoma (IA) groups. RESULTS: The values of pGGO (IC = 20.9 ± 6.2 mg/mL and WC = 345.1 ± 87.1 mg/mL) and mGGO (IC = 23.8 ± 8.3 mg/mL and WC = 606.8 ± 124.5 mg/mL) in the AP were significantly higher than those of the contralateral normal lung tissues (IC = 15.0 ± 4.9 mg/mL and WC = 156.4 ± 36.8 mg/mL; IC = 16.2 ± 5.7 mg/mL and WC = 169.4 ± 41.0 mg/mL) and ipsilateral normal lung tissues (IC = 15.1 ± 6.2 mg/mL and WC = 156.3 ± 38.8 mg/mL; IC = 15.9 ± 6.0 mg/mL and WC = 174.7 ± 39.2 mg/mL; all p < 0.001). After normalizing the data according to the values of the artery, pGGO (NIC = 0.1 and WC = 345.1 ± 87.1 mg/mL) and mGGO (NIC = 0.2 and WC = 606.8 ± 124.5 mg/mL) were statistically different (p = 0.049 and p < 0.001, respectively), but not for the IC value (p = 0.161). The WC values of the group with preinvasive lesions and MIA (345.4 ± 96.1 mg/mL) and IA (550.1 ± 158.2 mg/mL) were statistically different (p < 0.001). CONCLUSION: Using dual-energy spectral CT and material decomposition analysis, the IC in GGO can be quantitatively measured which can be an indicator of the blood supply status in the GGO.
Adenocarcinoma ; Arteries ; Humans ; Iodine ; Lung ; Multidetector Computed Tomography ; Retrospective Studies ; Tomography, X-Ray Computed ; Water