Experimental study on the effects of different exposure conditions and contrast agent concentrations on spectral computed tomography virtual non-contrast images.

Background: The early diagnosis of thrombosis and fat embolism is important for subsequent treatment regimens. Spectral computed tomography (CT) virtual non-contrast (VNC) scanning can not only accurately diagnose thrombosis and medium fat embolism but can also reduce the radiation dose and scanning time. However, there is a relative paucity of studies on what contrast concentration and exposure conditions are best for the quality of VNC images. To address this issue, this study aimed to investigate the effects of different exposure conditions and contrast concentrations on the quality of VNC images of low-density substances in spectral CT. Methods: Four solution groups [i.e., groups A (15 mgI/mL), B (10 mgI/mL), C (5 mgI/mL), and D (the control group)] were matched with normal saline and contrast agent groups. Four groups of solution, duck blood clots, and fat were injected into four sections of the pig large intestine, respectively. CT scans with different exposure amounts were performed under the condition of 120 KV. Comparing the true non-contrast (TNC) image based on solution D group with the VNC images of the other three solution groups. The differences in the CT values, standard deviation (SD) values, and contrast noise ratio (CNR) values of the duck blood and fat under different iodine concentrations and exposures were compared. The image quality was evaluated using a three-point method and the Kappa consistency test was performed. The consistency of the tissue CT values in the TNC and VNC images was analyzed by drawing Bland-Altman scatter plots. Results: The CT values of the duck blood in the VNC20mAs and VNCC groups were lower than those in the TNC groups (P<0.05). Under different exposures and contrast agent concentrations, the CT value of the fat in the VNC group was higher than that in the TNC group (P<0.05). The SD values of the duck blood and fat in three groups (i.e., groups A, B, and C) were lower than those in the TNC group (P<0.05). The CNR value of the duck blood in the VNC20mAs group was lower than that in the TNC group (Z=-2.10, P=0.04), and the CNR values of the duck blood and fat in the VNC group were higher than those in the TNC groups in the remaining different exposure and concentration groups (P<0.05). The CT values of the lesions in the two groups were consistent, and there were no statistically significant differences between the subjective scores of the TNC and VNC images (z=-1.34, P=0.18); the subjective evaluations of the two physicians had good consistency (K=0.80). Conclusions: Under the conditions of higher contrast agent concentrations and proper exposure conditions, the VNC images were better able to restore the CT values of the blood clots, reduce the SD values of the blood clots and fat. In addition, and improve the CNR values of the blood clots and fat. In addition, the quality of the two images was similar.

Assessment of early anthracycline-induced cardiotoxicity using segmental strain of cardiac magnetic resonance compared with global strain and functional parameters: an animal study.

Background: The identification of anthracycline-induced cardiotoxicity holds significant importance in guiding subsequent treatment strategies, and recent research has demonstrated the efficacy of cardiac magnetic resonance (CMR) global strain analysis for its diagnosis. On the other hand, it is noteworthy that abnormal global myocardial strain may exhibit a temporal delay due to different cardiac movement in each segment of the left ventricle. To address this concern, this study aims to assess the diagnostic utility of CMR segmental strain analysis as an early detection method for cardiotoxicity. Methods: A serials of CMR scans were performed in 18 adult males New Zealand rabbits at baseline time (n=15), followed by scans at week 2 (n=15), week 4 (n=9), week 6 (n=6), and week 8 (n=5) after each week's anthracycline injection. Additionally, following each CMR scan, two to three rabbits were euthanized for pathological comparison. Cardiac functional parameters, global peak strain parameters, segmental peak strain parameters of the left ventricle, and the presence of myocardial cells damage were obtained. A mixed linear model was employed to obtain the earliest CMR diagnostic time. Receiver operating characteristic (ROC) analysis was performed to get the parameter threshold indicative of cardiotoxicity. Results: The left ventricular ejection fraction decreased at week 8 (P=0.002). There were no statistical differences in global strain throughout the experiment period (P>0.05). Regarding segmental strain analysis, the peak segmental radial strain of the apical lateral wall exhibited a decrease starting from week 2 and reached its lowest point at this week (P=0.011). Conversely, peak segmental circumferential strain of the apical anterior wall showed an increase at week 2 and reached its peak at week 6 (P=0.026). The cutoff strain value by ROC analysis for these two walls were 46.285 and -16.920, with the respective areas under the curve (AUC) 0.593 [specificity =0.267, sensitivity =1.000, 95% confidence interval (CI): 0.471-0.777] and 0.764 (specificity =0.733, sensitivity =0.784, 95% CI: 0.511-0.816). Peak segmental longitudinal strain of the apical anterior and apical lateral wall showed relatively delayed changes, occurring in the 4th week (P=0.030 and P=0.048), the cutoff values for these strains were -12.415 and -15.960, with corresponding AUCs of 0.645 (specificity =0.333, sensitivity =0.955, 95% CI: 0.495-0.795) and 0.717 (specificity =0.433, sensitivity =0.955, 95% CI: 0.566-0.902), respectively. Notably, the myocardial injury was also observed at the corresponding periods. Conclusions: Based on experimental evidence, the peak segmental strain of the apical lateral and anterior wall, as determined by CMR, demonstrated an earlier detection of anthracycline-induced cardiotoxicity compared to peak global strain and cardiac function.

The relationship between coronary artery calcification and bone metabolic markers in maintenance hemodialysis patients.

BACKGROUND: To study the influencing factors for coronary artery calcification (CAC) in maintenance hemodialysis (MHD) patients and the relationship between CAC and bone metabolism markers and to attempt to find a reliable marker linking vascular calcification and bone metabolism in MHD patients. METHODS: A total of 123 patients were enrolled. CAC was assessed by multislice spiral computed tomography (MSCT), and the CAC score (CACS) was evaluated using the Agaston method. Routine laboratory parameters, including triglycerides (TG), total cholesterol (TC), glucose (Glu), calcium (Ca), phosphorus (P), magnesium (Mg), etc., were measured. Serum markers of bone metabolism, such as alkaline phosphatase(ALP), calcitonin (CT), 25-hydroxy vitamin D [25-(OH)D], intact parathyroid hormone (iPTH), total type I procollagen amino-terminal peptide (tPINP), N-terminal mid-fragment of osteocalcin (N-MID OC), and ß-type I collagen crosslinked carboxyl-terminal peptide (ß-CTX), were also measured. RESULTS: Among 123 MHD patients, 37 patients (30.08%) did not have CAC, and 86 patients (69.92%) had CAC, including 41 patients (47.67%) with mild calcification and 45 patients (52.33%) with moderate to severe calcification. Age, Body Mass Index(BMI), the prevalence of hypertension and diabetes mellitus, TC, Glu, P, and Ca×P in the calcification group were higher than those in the noncalcification group, whereas Mg, iPTH, tPINP, N-MID OC, and ß-CTX were lower than those in the noncalcified group (P < 0.05). Compared with the mild calcification group (0 0.05). A logistic regression model was used to evaluate the influencing factors for CAC. The results showed that age, BMI, TC, Glu, P, and Ca×P were risk factors for CAC and its severity in MHD patients, whereas diabetes mellitus, Mg, and N-MID OC were protective factors for CAC in MHD patients. In addition, N-MID OC was a protective factor for the severity of CAC. After adjusting for the corresponding confounding factors, the results of the risk factors were consistent, and N-MID OC was still an independent protective factor for CAC and its severity. CONCLUSIONS: Elevated serum P and Ca×P were independent risk factors for CAC in MHD patients, and serum Mg may be an independent protective factor for CAC. CAC was closely related to abnormal bone metabolism and bone metabolic markers in MHD patients. Relatively low bone turnover can promote the occurrence and development of CAC. N-MID OC may be a reliable bone metabolic marker linking vascular calcification and bone metabolism in MHD patients.

[Multi-slice spiral computed tomography angiography of internal pudendal arteries: imaging and value].

OBJECTIVE: To investigate the feasibility and value of multi-slice spiral computed tomography angiography (CTA) in 3D imaging of internal pudendal arteries and their branches. METHODS: Using 64-slice spiral computed tomography, we performed hypogastric CTA for 156 twenty to seventy years old males without vascular diseases. We assigned them to groups A (n = 83, 20 to 55 yr old) and B (n = 73, 56 to 70 yr old), and included 7 male patients with arterial erectile dysfunction (AED) aged 43 to 70 years in group C. We conducted maximum intensity projection (MIP), volume rendering (VR) and vascular analysis on the internal pudendal arteries and their branches, divided the MIP and VR images into 3 levels according to the resolution and continuity of the internal pudendal arteries and their branches for blind evaluation, and measured their diameters at various positions. RESULTS: VR images of the internal pudendal arteries and their branches revealed significant differences between groups A and B (P<0.05), but not MIP images (P>0.05). There were no dramatic differences between MIP and VR in displaying internal pudendal arteries and their branches (P>0.05), nor any remarkable differences in the diameters of bilateral internal pudendal arteries and their branches at different levels in groups A and B (P>0.05). VR and MIP showed the 7 AED cases at grade III, and clearly revealed the degree and position of stenosis and occlusion in the internal pudendal arteries and their branches. CONCLUSION: CTA can display clear 3D images of internal pudendal arteries and their branches, and has a valuable role in the diagnosis and treatment of ED induced by internal pudendal artery diseases.

[Effect of gene transfection at different time on bone mineral density and strength of newly formed bone in mandibular distraction gap in rabbit].

OBJECTIVE: To investigate the effect of gene transfection at different time on bone mineral density and strength of newly formed bone in mandibular distraction gap in rabbit, so as to explore the optimal time for gene therapy and enhance the therapeutic effect. METHODS: 48 New-Zealand rabbits were employed to receive mandibular osteotomy and implantation of distraction devices bilaterly. Then the rabbits were randomly divided into 4 groups as group A, B and C and D. The animals in group A, B, and C were transfected with recombinant plasmids pIRES-hBMP2-hVEGF165 via electroporation-mediated approach at latency period, distraction period, consolidation period respectively. Group D was used as control group without gene transfection. After 3 days of latency period, the distraction devices were activated at the rate of 0.8 mm per day for 10 days. Three rabbits in each group were sacrificed at 1 wk, 2 wk, 4 wk and 8 wk of consolidation respectively. The mandibles were harvested and the left mandible received X-ray examination for bone healing, and quantitative computed tomography (QCT) dectection for the bone mineral density (BMD) of newly formed bone in the distraction gap. The biomechanical properties of the new generation bone at 4 th and 8 th week of consolidation in each group were detected by three point bending test. RESULTS: The bone mineral density and the biomechanical strength of newly formed bone increased along the length of consolidation in each group. After 1 week of consolidation, there was no significant difference in BMD among group A (83.43 +/- 9.96), group B (92.29 +/- 11.25), group C (89.93 +/- 14.15), P > 0.05. But the BMD of group A, B and C was higher than that of group D (70. 31 +/- 3.30), P < 0.05. After 2wk, 4 wk and 8 wk of consolidation, the BMD of group B (137.54 +/- 7.20,492.93 +/- 17.57, 790.48 +/- 12.19) was significantly higher than those of group A (121.44 +/- 9.27, 396.15 +/- 15.70, 603.39 +/- 16.46), C (125.06 +/- 7.24, 464.15 +/- 15.45, 764.15 +/- 17.28), and D (98.86 +/- 8.13, 336.45 +/- 11.95, 577.89 +/- 18.43), P < 0.05. The biomechanical parameters were also higher in group B than those of group A, C and D after four and eight weeks of consolidation (P < 0.05). CONCLUSION: It is better to transfect gene at the beginning of distraction (distraction period) than at other stages of DO. In this way, more remarkable effect could be obtained on new bone formation. It suggests that the distraction stage is the optimal time for gene therapy.

[The effect of electroporation mediated gene therapy on bone mineral density and strength of new-formed bone in mandibular distraction gap in rabbit].

OBJECTIVE: To explore the effect of electroporation mediated gene therapy on bone mineral density and strength of new-formed bone in mandibular distraction gap, so as to enhance the osteogenesis and shorten the distraction term. METHODS: New-Zealand rabbits were employed. The distraction began after 3 days of latency period at the rate of 0. 8 mm per day for 7 days. After distraction, the rabbits were randomly divided into 5 groups to receive injection in the distraction gap with recombinant plasmid 2 microg (0.1 microg/microl) pIRES-hVEGF165-hBMP2 in group A, with recombinant plasmid pIRES-hBMP2 in group B, with recombinant plasmid pIRES-hVEGF165 in group C, with pIRES in group D, and with normal saline (NS) in group E. After injection, electroporation was performed in all the groups. After 1 week, 2 weeks, 4 weeks and 8 weeks of consolidation, all the animals underwent X-ray and quantitative computed tomography (QCT). The new-formed bone in distraction gap was selected as regions of interest (ROI) to measure the bone mineral density(BMD). Then the rabbits were sacrificed and the new-formed bone samples were harvested to detect 3-point crushing strength. RESULTS: BMD of newly formed bone in group A, B and C was markedly higher than that in group D and E (P < 0.01). After 2 weeks of consolidation, BMD in group A was much higher than that in the other groups, but there was no difference between group B and C. After 4 weeks of consolidation, BMD in group A and B was markedly higher than that in group C, D and E (P < 0.01). After 8 weeks of consolidation, BMD in group A was markedly higher than that in the other groups. While the BMD was not significantly different between group B and C, but the BMD in group B and C was higher than that in group D and E (P < 0.01). After 4 weeks of consolidation, the 3-point crushing strength of newly formed bone in group A was markedly higher than that in group B,C, D and E (P < 0.01), which was still the same after 8 weeks of consolidation. And the crushing strength in group B was higher than that in group C, D and E (P < 0. 05). CONCLUSIONS: Electroporation-mediated transfection of recombinant plasmid pIRES-hVEGF165-hBMP2 could greatly enhance osteogenesis and calcification. A combination of VEGF and BMP may promote osteogenesis and angiogenesis simultaneously, so as to magnify the effect of each growth factor, resulting a synergetic effect.