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ObjectiveTo compare the effect of contrast medium iodine concentration on contrast enhancement, heart rate, and injection pressure when injected at a constant iodine delivery rate in coronary CT angiography (CTA).MethodsOne thousand twenty-four patients scheduled for coronary CTA were prospectively randomized to receive one of four contrast media: iopromide 300 mg I/ml, iohexol 350 mg I/ml, iopromide 370 mg I/ml, or iomeprol 400 mg I/ml. Contrast media were delivered at an equivalent iodine delivery rate of 2.0 g I/s. Intracoronary attenuation was measured and compared (per vessel and per segment). Heart rate before and after contrast media injection was documented. Injection pressure was recorded (n = 403) during contrast medium injection and compared between groups.ResultsIntracoronary attenuation values were similar for the different contrast groups. The mean attenuation over all segments ranged between 384 HU for 350 mg I/ml and 395 HU for 400 mg I/ml (p = 0.079). Dose-length product (p = 0.8424), signal-to-noise ratio (all p > 0.05), time to peak (p = 0.324), and changes in heart rate (p = 0.974) were comparable between groups. The peak pressures differed: 197.4 psi for 300 mg I/ml (viscosity 4.6 mPa s), 229.8 psi for 350 mg I/ml (10.4 mPa s), 216.1 psi for 370 mg I/ml (9.5 mPa s), and 243.7 psi for 400 mg I/ml (12.6 mPa s) (p < 0.0001).ConclusionIntravascular attenuation and changes in heart rate are independent of iodine concentration when contrast media are injected at the same iodine delivery rate. Differences in injection pressures are associated with the viscosity of the contrast media.Key Points• The contrast enhancement in coronary CT angiography is independent of the iodine concentration when contrast media are injected at body temperature (37 °C) with the same iodine delivery rate.• Iodine concentration does not influence the change in heart rate when contrast media are injected at identical iodine delivery rates.• For a fixed iodine delivery rate and contrast temperature, the viscosity of the contrast medium affects the injection pressure.

ObjectivesTo determine the degree of relationship between iodine concentrations derived from dual-energy CT (DECT) and perfusion CT parameters in patients with advanced HCC under treatment.MethodsIn this single-centre IRB approved study, 16 patients with advanced HCC treated with sorafenib or radioembolization who underwent concurrent dynamic perfusion CT and multiphase DECT using a single source, fast kV switching DECT scanner were included. Written informed consent was obtained for all patients. HCC late-arterial and portal iodine concentrations, blood flow (BF)-related and blood volume (BV)-related perfusion parameters maps were calculated. Mixed-effects models of the relationship between iodine concentrations and perfusion parameters were computed. An adjusted p value (Bonferroni method) < 0.05 was considered significant.ResultsMean HCC late-arterial and portal iodine concentrations were 22.7±12.7 mg/mL and 18.7±8.3 mg/mL, respectively. Late-arterial iodine concentration was significantly related to BV (mixed-effects model F statistic (F)=28.52, p<0.0001), arterial BF (aBF, F=17.62, p<0.0001), hepatic perfusion index (F=28.24, p<0.0001), positive enhancement integral (PEI, F=66.75, p<0.0001) and mean slope of increase (F=32.96, p<0.0001), while portal-venous iodine concentration was mainly related to BV (F=29.68, p<0.0001) and PEI (F=66.75, p<0.0001).ConclusionsIn advanced HCC lesions, DECT-derived late-arterial iodine concentration is strongly related to both aBF and BV, while portal iodine concentration mainly reflects BV, offering DECT the ability to evaluate both morphological and perfusion changes.Key points• Late-arterial iodine concentration is highly related to arterial BF and BV.• Portal iodine concentration mainly reflects tumour blood volume.• Dual-energy CT offers significantly decreased radiation dose compared with perfusion CT.

This study aims to explore the feasibility of applying the “Three-Low” technique (low injection rate, low iodine contrast volume, low radiation dose) in coronary CT angiography (CCTA). We prospectively collected data from 90 patients who underwent CCTA at our hospital between 2021 and 2024. The patients were randomly assigned to either the experimental group ( n  = 45) or the control group ( n  = 45). The experimental group parameters were as follows: injection rate of 3.5-4.0 ml/s, iodine contrast volume of 35–40 ml, tube voltage of 100 kVp, and tube current of 250 mA. The control group parameters were: injection rate of 4.5-5.0 ml/s, iodine contrast volume of 45–50 ml, tube voltage of 120 kVp, and tube current of 450 mA. Both groups received a high-concentration, non-ionic, water-soluble contrast agent (Iomeprol, 40 gl/100 ml). The heart rate of all patients was ≤ 70 bpm, and breath-hold scanning was performed after breathing training. The study compared the CT values of the left anterior descending artery, left circumflex artery, right coronary artery, and aorta, as well as background noise, signal-to-noise ratio (SNR), volumetric CT dose index, dose-length product, effective radiation dose, and total iodine dose between the two groups. In the control group, no cases of contrast extravasation occurred, while 6 cases of extravasation were observed in the experimental group ( p  = 0.026). There was no significant difference between the groups in terms of vascular image quality (mean vascular image quality score: experimental group 4.27 ± 0.62 vs. control group 4.24 ± 0.57, p  > 0.05) or vascular motion artifact score (mean vascular motion artifact score: experimental group 4.20 ± 0.59 vs. control group 4.13 ± 0.55, p  > 0.05). However, significant differences were found between the experimental and control groups in the CT values of the left anterior descending artery (experimental group: 571.31 ± 49.66 HU vs. control group: 449.20 ± 36.80 HU, p  < 0.05), left circumflex artery (experimental group: 570.41 ± 49.98 HU vs. control group: 450.95 ± 39.27 HU, p  < 0.05), right coronary artery (experimental group: 584.52 ± 53.70 HU vs. control group: 452.66 ± 40.67 HU, p  < 0.05), aorta (experimental group: 624.91 ± 48.99 HU vs. control group: 465.36 ± 34.37 HU, p  < 0.05), background noise (experimental group: 24.76 ± 1.97 vs. control group: 19.09 ± 1.69, p  < 0.05), SNR (experimental group: 25.30 ± 1.81 vs. control group: 24.47 ± 1.75, p  < 0.05), volumetric CT dose index (experimental group: 22.97 ± 1.47 mGy vs. control group: 50.53 ± 4.89 mGy, p  < 0.05), dose-length product (experimental group: 363.68 ± 21.45 mGy·cm vs. control group: 782.41 ± 58.20 mGy·cm, p  < 0.05), and effective radiation dose (experimental group: 5.09 ± 0.30 mSv vs. control group: 10.95 ± 0.81 mSv, p  < 0.05).The results of the Fisher test indicated that the extravasation rate was significantly higher in the high injection rate group compared to the low injection rate group ( P  = 0.024). The “Three-Low” technique in CCTA imaging effectively reduces the incidence of contrast extravasation caused by high injection rates and decreases the radiation dose, making it a highly feasible option for clinical application and worthy of broader adoption.

Objectives Contrast media (CM) extravasation is a well-known complication of CT angiography (CTA). Our prospective randomized control study aimed to assess whether a four-phasic CM administration protocol reduces the risk of extravasation compared to the routinely used three-phasic protocol in coronary CTA. Methods Patients referred to coronary CTA due to suspected coronary artery disease were included in the study. All patients received 400 mg/ml iomeprol CM injected with dual-syringe automated injector. Patients were randomized into a three-phasic injection-protocol group, with a CM bolus of 85 ml followed by 40 ml of 75%:25% saline/CM mixture and 30 ml saline chaser bolus; and a four-phasic injection-protocol group, with a saline pacer bolus of 10 ml injected at a lower flow rate before the three-phasic protocol. Results 2,445 consecutive patients were enrolled (mean age 60.6 ± 12.1 years; females 43.6%). Overall rate of extravasation was 0.9% (23/2,445): 1.4% (17/1,229) in the three-phasic group and 0.5% (6/1,216) in the four-phasic group (p = 0.034). Conclusions Four-phasic CM administration protocol is easy to implement in the clinical routine at no extra cost. The extravasation rate is reduced by 65% with the application of the four-phasic protocol compared to the three-phasic protocol in coronary CTA. Key Points • Four-phasic CM injection-protocol reduces extravasation rate by 65% compared to three-phasic. • The saline pacer bolus substantially reduces the risk of CM extravasation. • The implementation of four-phasic injection-protocol is at no cost.

ObjectivesTo investigate the clinical utility of our newly developed contrast enhancement optimizer (CEO) software for coronary CT angiography (CCTA).MethodsWe randomly assigned 295 patients (168 males, 127 females, median age 71 years) undergoing CCTA to one of two contrast media injection protocols. Group A (n = 150) was injected with a CEO-selected iodine dose based on patient factors. In group B (n = 145), we used our standard protocol (245 mg I/kg). We recorded the CT number in the ascending aorta and determined whether the CT number was equivalent in groups A and B. For the equivalence test, we adopted 75 Hounsfield units (HU) as the equivalence margin. The standard deviation in the CT number and the rate of patients with an acceptable CT number were compared using the F test and the chi-square test, respectively.ResultsThe iodine dose in group A was significantly smaller than that in group B (235.7 vs. 253.6 mg I/kg, p < 0.001). The CT number of the ascending aorta was 428.6 ± 55.5 HU in group A and 436.1 ± 68.7 HU in group B; the 95% confidence interval for the difference between the groups was -4.3 HU to 16.9 HU and within the range of the predetermined equivalence margins. In group A, the variance was significantly smaller than that in group B (p = 0.009). The number of patients with an acceptable CT number was significantly higher in group A than in group B (84.7% vs. 71.7%, p = 0.007).ConclusionsThe use of our CEO for CCTA studies yielded optimal aortic contrast enhancement in significantly more patients than the standard protocol based on the body weight.Key Points• With our contrast enhancement optimizer (CEO) software, optimal and stable aortic enhancement can be obtained on coronary CT angiography scans irrespective of patient factors.• Management of contrast media becomes more appropriate by the CEO software.• The CEO software can control contrast enhancement at different tube voltage levels.

Objectives To compare a low-tube-voltage with or without high-iodine-load multidetector CT (MDCT) protocol with a normal-tube-voltage, normal-iodine-load (standard) protocol in patients with pancreatic ductal adenocarcinoma (PDAC) with respect to tumour conspicuity and image quality. Methods Thirty consecutive patients (mean age: 66 years, men/women: 14/16) preoperatively underwent triple-phase 64-channel MDCT examinations twice according to: (i) 120-kV standard protocol (PS; 0.75 g iodine (I)/kg body weight, n = 30) and (ii) 80-kV protocol A (PA; 0.75 g I/kg, n = 14) or protocol B (PB; 1 g I/kg, n = 16). Two independent readers evaluated tumour delineation and image quality blindly for all protocols. A third reader estimated the pancreas-to-tumour contrast-to-noise ratio (CNR). Statistical analysis was performed with the Chi-square test. Results Tumour delineation was significantly better in PB and PA compared with PS ( P  = 0.02). The evaluation of image quality was similar for the three protocols (all, P  > 0.05). The highest CNR was observed with PB and was significantly better compared to PA ( P  = 0.02) and PS ( P  = 0.0002). Conclusion In patients with PDAC, a low-tube-voltage, high-iodine-load protocol improves tumour delineation and CNR leading to higher tumour conspicuity compared to standard protocol MDCT. Key Points • Low-tube-voltage high-iodine-load MDCT improves pancreatic cancer conspicuity compared to a standard protocol. • The pancreas-to-tumour attenuation difference increases significantly by reducing the tube voltage. • The radiation exposure dose decreases by reducing the tube voltage.

Purpose To prospectively compare two different approaches for estimating the amount of intravenous contrast media (CM) needed for multiphasic MDCT of the liver in obese patients. Materials and methods This single-center, HIPAA-compliant prospective study was approved by our Institutional Review Board. Ninety-six patients (55 men, 41 women), with a total of 42 hypovascular liver lesions, underwent MDCT of the liver. The amount of contrast medium injected was computed according to the patient’s lean body weight which was estimated using either a bioimpedance device (Group A) or the James formula (Group B). The following variables were compared between the two groups: the amount of contrast medium injected (in grams of Iodine, gI), the contrast enhancement index (CEI) and the lesion-to-liver contrast-to-noise ratio. Results Protocols A and B yielded significant differences in the amount of CM injected (mean values 41.9 ± 4.41 gI in Group A vs. 35.9 ± 5.75 gI in Group B; P  = 0.021). The mean CEI value and lesion-to-liver contrast-to-noise ratio measured on the portal phase were significantly higher with protocol A than with protocol B ( P  < 0.05). Conclusions Our study shows that the adoption of a bioimpedance device in obese patients improves liver parenchymal enhancement and lesion conspicuity.

Objectives The differences regarding adverse reactions in different low-osmolar non-ionic contrast media had not been investigated previously. Thus, the aims of this study were to identify differences in the incidence of adverse reactions in five different low-osmolar non-ionic contrast media. Methods We prospectively recorded all adverse events associated with five different low-osmolar non-ionic contrast media used in 8,931 consecutive patients for CT. Patients were randomly assigned to five groups: iomeprol 300 mgI/ml, iopamidol 300 mgI/ml, iohexol 300 mgI/ml, iopromide 300 mgI/ml and ioversol 320 mgI/ml. Results Adverse events were observed in 241 patients (2.7%). The incidence of acute adverse reactions was significantly higher in the following groups: (1) iomeprol (3.9%) and iopromide (3.5%) groups, (2) patients aged 59 years or less (4.5%) compared with those aged 60 years or over (1.9%), (3) the first period (3.5%) compared with the late period (2.3%), (4) those with a past history of adverse reactions to contrast media (11.2%), and (5) patients receiving contrast media for the first time (3.3%) compared with those had received it previously (2.0%). Conclusion The incidence of acute adverse reactions may be reduced in younger patients by using iopamidol, iohexol and ioversol.

The purpose of this study was to compare the ability of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) to evaluate treatment results after transarterial chemoembolization (TACE), with a special focus on the influence of Lipiodol on calculation of tumor necrosis according to EASL criteria. A total of 115 nodules in 20 patients (17 males, 3 females; 69.5 ± 9.35 years) with biopsy-proven hepatocellular carcinoma were treated with TACE. Embolization was performed using a doxorubicin-Lipiodol emulsion (group I) or DC Beads loaded with doxorubicin (group II). Follow-up included triphasic contrast-enhanced 64-row MDCT (collimation, 0.625 mm; slice, 3 mm; contrast bolus, 120 ml iomeprol; delay by bolus trigger) and contrast-enhanced MRI (T1 native, T2 native; five dynamic contrast-enhanced phases; 0.1 mmol/kg body weight gadolinium-DTPA; slice thickness, 4 mm). Residual tumor and the extent of tumor necrosis were evaluated according to EASL. Contrast enhancement within tumor lesions was suspected to represent vital tumor. In the Lipiodol-based TACE protocol, MDCT underestimated residual viable tumor compared to MRI, due to Lipiodol artifacts (23.2% vs 47.7% after first, 11.9% vs 31.2% after second, and 11.4% vs 23.7% after third TACE; p  = 0.0014, p  < 0.001, and p  < 0.001, respectively). In contrast to MDCT, MRI was completely free of any artifacts caused by Lipiodol. In the DC Bead-based Lipiodol-free TACE protocol, MRI and CT showed similar residual tumor and rating of treatment results (46.4% vs 41.2%, 31.9 vs 26.8%, and 26.0% vs 25.6%; n.s.). In conclusion, MRI is superior to MDCT for detection of viable tumor residuals after Lipiodol-based TACE. Since viable tumor tissue is superimposed by Lipiodol artifacts in MDCT, MRI is mandatory for reliable decision-making during follow-up after Lipiodol-based TACE protocols.

The incidence of contrast-medium-induced nephropathy (CIN) following intravenous (IV) CM administration of contrast media to renally impaired patients undergoing multidetector computed tomography (MDCT) is not well characterized. Our objective was to investigate the incidence of CIN in patients with glomerular filtration rate (GFR) <60 ml/min undergoing contrast-enhanced MDCT examinations and to compare the rates of CIN following the IV administration of low-osmolar contrast media (LOCM, iopamidol and iomeprol) and an iso-osmolar contrast medium (IOCM, iodixanol). A total of 301 adult patients with moderate-to-severe renal failure received a similar IV contrast dose (40 gI). Serum creatinine (SCr) was measured at screening, baseline and 48–72 ± 6 h after the MDCT examination. Primary CIN outcome was an increase in SCr ≥0.5 mg/dl (≥44.2 μmol/l) from baseline. The CIN rates were 2.3% in the total population, 0.6% when GFR >40 ml/min, 4.6% when GFR <40 ml/min and 7.8% in patients with GFR <30 ml/min. The incidence of CIN was significantly higher after iodixanol than after LOCM (seven patients, 4.7% following IOCM, no CIN cases following the LOCM; p = 0.007). Significant differences in favor of the LOCM were also observed in patients with GFR <40 ml/min and GFR <30 ml/min. Following the IV administration of nonionic contrast agents in patients with moderate-to-severe renal insufficiency, the risk of significant CIN seems to be low. The IOCM iodixanol caused a higher rate of CIN than the LOCM iopamidol and iomeprol, especially in high-risk patients. Differences in osmolality between these LOCM and iodixanol do not play a role in the genesis of CIN.