Plasma lipids in Pseudoxanthoma Elasticum (PXE) patients: A comparative study with population-based reference values and Non-PXE controls.

Background and aims: - Pseudoxanthoma elasticum (PXE) is a rare genetic disease caused by pathogenic mutations in the ABCC6 gene, resulting in low values of inorganic pyrophosphate (PPi). While low PPi is thought to contribute to arterial calcification, it remains unclear whether this fully explains premature calcification in PXE. It has been hypothesized that the ABCC6 gene could be related to dyslipidemia, which could contribute to vascular calcification seen in PXE. The aim of this study is to evaluate the relation between PXE and plasma lipid concentrations in a large cohort of PXE patients compared with reference values for the general population and compared with non-PXE controls. Methods: - The plasma concentrations of total cholesterol, HDL-cholesterol, tiglycerides, and LDL-cholesterol of 312 PXE patients were compared to age- and sex-matched modeled data of the general Dutch population. Differences in median lipid levels were compared with Mann-Whitney-U test. Secondly, plasma lipid concentrations of 44 PXE patients were compared to 44 not-genetically related relatives (spouses or friends), with linear models adjusted for age, sex and BMI. Results: - Total cholesterol in PXE patients was 5.6 [IQR 4.6-6.4] mmol/L versus 5.3 [IQR 4.7-6.0] mmol/L (p < 0.01) in the general population; triglycerides were 1.1 [IQR 0.9-1.7] mmol/L versus 1.0 [0.7-1.4] mmol/L (p < 0.01); HDL-c was 1.4 [IQR 1.2-1.7] mmol/L versus 1.5 [IQR 1.2-1.8] mmol/L (p = 0.03) and LDL-c was 3.3 [IQR 2.7-4.1] mmol/L versus 3.2 [IQR 2.7-3.8] mmol/L (p = 0.01). In the patient control analysis with 44 pairs and age, sex and BMI adjusted, comparison with the non-PXE controls only triglycerides were significantly different (mean difference: 0.38 (0.13-0.63)). Conclusion: -The lipid profiles of PXE patients are marginally different from the general population or compared to a matched control group, but the differences are unlikely to be clinically relevant. It is therefore unlikely that plasma lipids contribute to the premature vascular calcifications in PXE patients.

Do pseudoxanthoma elasticum patients have higher prevalence of kidney stones on computed tomography compared to hospital controls?

BACKGROUND: Pseudoxanthoma elasticum (PXE) is an autosomal recessive disease characterized by diminished inorganic plasma pyrophosphate (PPi), a strong calcification inhibitor. In addition to more typical calcification of skin, retina and arterial wall a diminished plasma PPi could lead to other ectopic calcification, such as formation of kidney stones. OBJECTIVE: To compare the prevalence of kidney stones between PXE patients and hospital controls on computed tomography (CT). METHOD: Low-dose CT images of PXE patients and controls were assessed by one radiologist, who was blinded for the diagnosis PXE. The number of kidney stones, and the size of the largest stone was recorded. Odds ratios (ORs) for having kidney stone were calculated using multivariable adjusted logistic regression. RESULTS: Our study comprised 273 PXE patients and 125 controls. The mean age of PXE patients was 51.5 ± 15.9 years compared to 54.9 ± 14.2 in the control group (p = 0.04) and PXE patients more often were women (63 vs. 50%, p = 0.013). The prevalence of kidney stones on CT was similar: 6.9% in PXE patients, compared to 5.6% in controls (p = 0.6). In the multivariate analysis adjusting for age and sex, there was no significantly higher odds for PXE patients on having stones, compared to controls: OR 1.48 (95% CI 0.62-3.96). CONCLUSION: There is no significant difference in the prevalence of incidental kidney stones on CT in PXE patients versus controls.

Incidental Indeterminate Renal Lesions: Distinguishing Non-Enhancing from Potential Enhancing Renal Lesions Using Iodine Quantification on Portal Venous Dual-Layer Spectral CT.

The purpose of our study is to determine a threshold for iodine quantification to distinguish definitely non-enhancing benign renal lesions from potential enhancing masses on portal venous dual-layer spectral computed tomography (CT) to reduce the need for additional multiphase CT. In this single-center retrospective study, patients (≥18 years) scanned between April 2021 and January 2023 following the local renal CT protocol were included. Exclusion criteria were patients without renal lesions, lesions smaller than 10 mm, only fat-containing lesions, abscesses or infarction, follow-up after radiofrequent ablation, wrong scan protocol, or artefacts. Scans were performed on a dual layer detector-based spectral CT (CT 7500, Philips Healthcare, Best, The Netherlands). Iodine concentration (mgI/mL) in renal lesions was determined using spectral data. Analyses were performed for all lesions and for lesions of >30 HU on portal venous CT. Enhancement on multiphase CT (≥20 ΔHU from true unenhanced (TUE) to portal venous phase (PVP) CT) was used as reference standard. To determine thresholds for iodine concentration receiver operating characteristic (ROC) curves, area under the curve (AUC) and 95% confidence intervals were calculated. To obtain thresholds for definite (non-)enhancement, 100% sensitivity with maximum specificity and 100% specificity with maximum sensitivity were noted. Data were measured using one reader. To assess interobserver agreement, a second reader performed measurements on the PVP CT scans. A total of 103 patients (62 years ± 14, 68 men) were included. We measured 328 renal lesions, 56 enhancing lesions (17%) in 38 patients and 272 non-enhancing lesions (83%) in 86 patients. The threshold for non-enhancing lesions was 0.76 mgI/mL or lower (100% sensitivity, 76% specificity). The threshold for a definite enhancing mass was 1.69 mgI/mL or higher (100% specificity, 78% sensitivity). A total of 77% of indeterminate lesions (>30 HU on PVP CT) in our study could be definitely characterized. Renal lesions can be definitively classified as non-enhancing or enhancing on PVP spectral CT using thresholds of 0.76 mgI/mL or 1.69 mgI/mL, respectively, eliminating the need for multiphase imaging.

BMI is not independently associated with coronary artery calcification in a large single-center CT cohort.

Objective: Obesity is associated with cardiovascular disease (CVD) and CVD mortality. However, previous reports showed a paradoxical protective effect in patients with known CVD referred as "obesity paradox". Therefore, the aim of the present study was to investigate the association of body mass index (BMI) with coronary artery calcification (CAC) in a large outpatient cardiac CT cohort. Methods: 4.079 patients who underwent cardiac CT between December 2007-May 2014 were analyzed. BMI and clinical risk factors (current smoking, diabetes mellitus type 2, family history, systolic blood pressure, lipid spectrum) were assessed. Missing values were imputed using multiple imputation. CAC extent was categorized as absent (0), mild (>0-100), moderate (>100-400) and severe (>400). Results: Multivariable multinomial logistic regression analysis, including all risk factors as independent variables, showed no association between BMI and CAC. Using absence of calcification as reference category, the odds ratios per unit increase in BMI were 1.01 for mild; 1.02 for moderate; and 1.00 for severe CAC (p-values ≥0.103). Conclusions: No statistically significant association was observed between BMI and CAC after adjustment for other risk factors.

Individualized Contrast Media Application Based on Body Weight and Contrast Enhancement in Computed Tomography of Livers without Steatosis.

This study analyzes the homogeneity in liver attenuation of a body-weight-based protocol compared to a semi-fixed protocol. Patients undergoing abdominal multiphase computed tomography received 0.500 g of iodine (gI) per kilogram of body weight. Liver attenuation and enhancement were determined using regions of interest on scans in the pre-contrast and portal venous phases. The outcomes were analyzed for interpatient uniformity in weight groups. The subjective image quality was scored using a four-point Likert scale (excellent, good, moderate, and nondiagnostic). A total of 80 patients were included (56.3% male, 64 years, 78.0 kg) and were compared to 80 propensity-score-matched patients (62.5% male, 63 years, 81.7 kg). The liver attenuation values for different weight groups of the TBW-based protocol were not significantly different (p = 0.331): 109.1 ± 13.8 HU (≤70 kg), 104.6 ± 9.70 HU (70−90 kg), and 105.1 ± 11.6 HU (≥90 kg). For the semi-fixed protocol, there was a significant difference between the weight groups (p < 0.001): 121.1 ± 12.1 HU (≤70 kg), 108.9 ± 11.0 HU (70−90 kg), and 105.0 ± 9.8 HU (≥90 kg). For the TBW-based protocol, the enhancement was not significantly different between the weight groups (p = 0.064): 46.2 ± 15.1 HU (≤70 kg), 59.3 ± 6.8 HU (70−90 kg), and 52.1 ± 11.7 HU (≥90 kg). Additionally, for the semi-fixed protocol, the enhancement was not significantly different between the weight groups (p = 0.069): 59.4 ± 11.0 HU (≤70 kg), 53.0 ± 10.3 HU (70−90 kg), and 52.4 ± 7.5 HU (≥90 kg). The mean administered amount of iodine per kilogram was less for the TBW-based protocol compared to the semi-fixed protocol: 0.499 ± 0.012 and 0.528 ± 0.079, respectively (p = 0.002). Of the TBW-based protocol, 17.5% of the scans scored excellent enhancement quality, 76.3% good, and 6.3% moderate. Of the semi-fixed protocol, 70.0% scored excellent quality, 21.3% scored good, and 8.8% scored moderate. In conclusion, the TBW-based protocol increased the interpatient uniformity of liver attenuation but not the enhancement in the portal venous phase compared to the semi-fixed protocol, using an overall lower amount of contrast media and maintaining good subjective image quality.

Quantification of Calcium in Peripheral Arteries of the Lower Extremities: Comparison of Different CT Scanners and Scoring Platforms.

OBJECTIVES: The aim of this study was to investigate the interscanner and interscoring platform variability of calcium quantification in peripheral arteries of the lower extremities. MATERIALS AND METHODS: Twenty human fresh-frozen legs were scanned using 3 different computed tomography (CT) scanners. The radiation dose (CTDIvol) was kept similar for all scanners. The calcium scores (Agatston and volume scores) were quantified using 4 semiautomatic scoring platforms. Comparative analysis of the calcium scores between scanners and scoring platforms was performed by using the Friedman test; post hoc analysis was performed by using the Wilcoxon signed rank test with Bonferroni correction. RESULTS: Sixteen legs had calcifications and were used for data analysis. Agatston and volume scores ranged from 12.1 to 6580 Agatston units and 18.2 to 5579 mm3. Calcium scores differed significantly between Philips IQon and Philips Brilliance 64 (Agatston: 19.5% [P = 0.001]; volume: 14.5% [P = 0.001]) and Siemens Somatom Force (Agatston: 18.1% [P = 0.001]; volume: 17.5% [P = 0.001]). The difference between Brilliance 64 and Somatom Force was smaller (Agatston: 5.6% [P = 0.778]; volume: 7.7% [P = 0.003]). With respect to the interscoring platform variability, OsiriX produced significantly different Agatston scores compared with the other 3 scoring platforms (OsiriX vs IntelliSpace: 14.8% [P = 0.001] vs Syngo CaScore: 13.9% [P = 0.001] vs iX viewer: 13.2% [P < 0.001]). For the volume score, the differences between all scoring platforms were small ranging from 2.9% to 4.0%. Post hoc analysis showed a significant difference between OsiriX and IntelliSpace (3.8% [P = 0.001]). CONCLUSIONS: The use of different CT scanners resulted in notably different Agatston and volume scores, whereas the use of different scoring platforms resulted in limited variability especially for the volume score. In conclusion, the variability in calcium quantification was most evident between different CT scanners and for the Agatston score.

Computed tomography-based calcium scoring in cadaver leg arteries: Influence of dose, reader, and reconstruction algorithm.

PURPOSE: Computed tomography (CT) might be a good diagnostic test to accurately quantify calcium in vascular beds but there are multiple factors influencing the quantification. The aim of this study was to investigate the influence of different computed tomography protocol settings in the quantification of calcium in the lower extremities using modified Agatston and volume scores. METHODS: Fresh-frozen human legs were scanned at different tube current protocols and reconstructed at different slice thickness. Two different iterative reconstruction protocols for conventional CT images were compared. Calcium was manually scored using modified Agatston and volume scores. Outcomes were statistically analyzed using Wilcoxon signed-rank tests and mean absolute and relative differences were plotted in Bland-Altman plots. RESULTS: Of the 20 legs, 16 had CT detectable calcifications. Differences between thick and thin slice reconstruction protocols were 129 Agatston units and 125% for Agatston and 78.4 mm3 and 57.8% for volume (all p ≤ 0.001). No significant differences were found between low and high tube current protocols. Differences between iDose4 and IMR reconstruction protocols for modified Agatston were 34.2 Agatston units and 17.7% and the volume score 33.5 mm3 and 21.2% (all p ≤ 0.001). CONCLUSIONS: Slice thickness reconstruction and reconstruction method protocols influenced the modified Agatston and volume scores in leg arteries, but tube current and different observers did not have an effect. This data emphasizes the need for standardized quantification of leg artery calcifications. Possible implications are in the development of a more universal quantification method, independent of the type of scan and vasculature.

Liver Enhancement on Computed Tomography Is Suboptimal in Patients with Liver Steatosis.

This study's aim was twofold. Firstly, to assess liver enhancement quantitatively and qualitatively in steatotic livers compared to non-steatotic livers on portal venous computed tomography (CT). Secondly, to determine the injection volume of contrast medium in patients with severe hepatic steatosis to improve the image quality of the portal venous phase. We retrospectively included patients with non-steatotic (n = 70), the control group, and steatotic livers (n = 35) who underwent multiphase computed tomography between March 2016 and September 2020. Liver enhancement was determined by the difference in attenuation in Hounsfield units (HU) between the pre-contrast and the portal venous phase, using region of interests during in three different segments. Liver steatosis was determined by a mean attenuation of ≤40 HU on unenhanced CT. Adequate enhancement was objectively defined as ≥50 ΔHU and subjectively using a three-point Likert scale. Enhancement of non-steatotic and steatotic livers were compared and associations between enhancement and patient- and scan characteristics were analysed. Enhancement was significantly higher among the control group (mean 51.9 ± standard deviation 11.5 HU) compared to the steatosis group (40.6 ± 8.4 HU p for difference < 0.001). Qualitative analysis indicated less adequate enhancement in the steatosis group: 65.7% of the control group was rated as good vs. 8.6% of the steatosis group. We observed a significant correlation between enhancement, and presence/absence of steatosis and grams of iodine per total body weight (TBW) (p < 0.001; adjusted R2 = 0.303). Deduced from this correlation, theoretical contrast dosing in grams of Iodine (g I) can be calculated: g I = 0.502 × TBW for non-steatotic livers and g I = 0.658 × TBW for steatotic livers. Objective and subjective enhancement during CT portal phase were significantly lower in steatotic livers compared to non-steatotic livers, which may have consequences for detectability and contrast dosing.

Towards Personalised Contrast Injection: Artificial-Intelligence-Derived Body Composition and Liver Enhancement in Computed Tomography.

In contrast-enhanced computed tomography, total body weight adapted contrast injection protocols have proven successful in achieving a homogeneous enhancement of vascular structures and liver parenchyma. However, because solid organs have greater perfusion than adipose tissue, the lean body weight (fat-free mass) rather than the total body weight is theorised to cause even more homogeneous enhancement. We included 102 consecutive patients who underwent a multiphase abdominal computed tomography between March 2016 and October 2019. Patients received contrast media (300 mgI/mL) according to bodyweight categories. Using regions of interest, we measured the Hounsfield unit (HU) increase in liver attenuation from unenhanced to contrast-enhanced computed tomography. Furthermore, subjective image quality was graded using a four-point Likert scale. An artificial intelligence algorithm automatically segmented and determined the body compositions and calculated the percentages of lean body weight. The hepatic enhancements were adjusted for iodine dose and iodine dose per total body weight, as well as percentage lean body weight. The associations between enhancement and total body weight, body mass index, and lean body weight were analysed using linear regression. Patients had a median age of 68 years (IQR: 58-74), a total body weight of 81 kg (IQR: 73 - 90), a body mass index of 26 kg/m2 (SD: ±4.2), and a lean body weight percentage of 50% (IQR: 36 - 55). Mean liver enhancements in the portal venous phase were 61 ± 12 HU (≤ 70 kg), 53 ± 10 HU (70 - 90 kg), and 53 ± 7 HU (≥ 90 kg). The majority (93%) of scans were rated as good or excellent. Regression analysis showed significant correlations between liver enhancement corrected for injected total iodine and total body weight (r = 0.53; p < 0.001) and between liver enhancement corrected for lean body weight and the percentage of lean body weight (r = 0.73; p < 0.001). Most benefits from personalising iodine injection using %LBW additive to total body weight would be achieved in patients under 90 kg. Liver enhancement is more strongly associated with the percentage of lean body weight than with the total body weight or body mass index. The observed variation in liver enhancement might be reduced by a personalised injection based on the artificial-intelligence-determined percentage of lean body weight.

Optimizing Pulmonary Embolism Computed Tomography in the Age of Individualized Medicine: A Prospective Clinical Study.

PURPOSE: The aim of the study was to simultaneously optimize contrast media (CM) injection and scan parameters for the individual patient during computed tomography pulmonary angiography (CTPA). METHODS: In this study (NCT02611115), 235 consecutive patients suspected of having pulmonary embolism were prospectively enrolled. Automated kV selection software on a third-generation multidetector computed tomography adapted tube voltage to the individual patient, based on scout scans. The contrast injection protocol was adapted to both patient body weight and kV-setting selection via a predefined formula, based on previous research. Injection data were collected from a contrast media and radiation dose monitoring software. Attenuation was measured in Hounsfield units (HU) in the pulmonary trunk (PT); attenuation values 200 HU or greater were considered diagnostic. Subjective image quality was assessed by using a 4-point Likert scale at the level of the PT, lobar, segmental, and subsegmental arteries. Results between groups were reported as mean ± SD. RESULTS: Two hundred twenty-two patients (94%) were scanned at a kV setting below 100 kV: n = 108 for 70 kV, n = 82 for 80 kV, and n = 32 for 90 kV. Mean CM bolus volume (in milliliters) and total iodine load (in grams of iodine) for 70 to 90 kV were as follows: 24 ± 3 mL and 7 ± 1 g I, 29 ± 4 mL and 9 ± 2 g I, and 38 ± 4 mL and 11 ± 1 g I, respectively. Mean flow rates (in milliliters per second) and iodine delivery rates (in grams of iodine per second) were 3.0 ± 0.4 mL/s and 0.9 ± 0.1 g I/s (70 kV), 3.6 ± 0.4 mL/s and 1.0 ± 0.1 g I/s (80 kV), and 4.7 ± 0.5 mL/s and 1.3 ± 0.1 g I/s (90 kV). Mean radiation doses were 1.3 ± 0.3 mSv at 70 kV, 1.7 ± 0.4 mSv at 80 kV, and 2.2 ± 0.6 mSv at 90 kV. Mean vascular attenuation in the PT for each kV group was as follows: 397 ± 101 HU for 70 kV, 398 ± 96 HU for 80 kV, and 378 ± 100 HU for 90 kV, P = 0.59. Forty-six patients (21%) showed pulmonary embolism on the CTPA. One scan (90 kV) showed nondiagnostic segmental pulmonary arteries, and 5% of subsegmental arteries were of nondiagnostic image quality. All other segments were considered diagnostic-excellent subjective image quality. CONCLUSIONS: Simultaneously optimizing both CM injections and kV settings to the individual patient in CTPA results in diagnostic attenuation with on average 24 to 38 mL of CM volume and a low radiation dose for most patients. This individualized protocol may help overcome attenuation-variation problems between patients and kV settings in CTPA.

Contrast Media Administration in Coronary Computed Tomography Angiography - A Systematic Review.

Background Various different injection parameters influence enhancement of the coronary arteries. There is no consensus in the literature regarding the optimal contrast media (CM) injection protocol. The aim of this study is to provide an update on the effect of different CM injection parameters on the coronary attenuation in coronary computed tomographic angiography (CCTA). Method Studies published between January 2001 and May 2014 identified by Pubmed, Embase and MEDLINE were evaluated. Using predefined inclusion criteria and a data extraction form, the content of each eligible study was assessed. Initially, 2551 potential studies were identified. After applying our criteria, 36 studies were found to be eligible. Studies were systematically assessed for quality based on the validated Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-II checklist. Results Extracted data proved to be heterogeneous and often incomplete. The injection protocol and outcome of the included publications were very diverse and results are difficult to compare. Based on the extracted data, it remains unclear which of the injection parameters is the most important determinant for adequate attenuation. It is likely that one parameter which combines multiple parameters (e. g. IDR) will be the most suitable determinant of coronary attenuation in CCTA protocols. Conclusion Research should be directed towards determining the influence of different injection parameters and defining individualized optimal IDRs tailored to patient-related factors (ideally in large randomized trials). Key points · This systematic review provides insight into decisive factors on coronary attenuation.. · Different and contradicting outcomes are reported on coronary attenuation in CCTA.. · One parameter combining multiple parameters (IDR) is likely decisive in coronary attenuation.. · Research should aim at defining individualized optimal IDRs tailored to individual factors.. · Future directions should be tailored towards the influence of different injection parameters.. Citation Format · Mihl C, Maas M, Turek J et al. Contrast Media Administration in Coronary Computed Tomography Angiography - A Systematic Review. Fortschr Röntgenstr 2017; 189: 312 - 325.

Optimizing contrast media application in coronary CT angiography at lower tube voltage: Evaluation in a circulation phantom and sixty patients.

PURPOSE: The purpose was to investigate optimal contrast media (CM) injection parameters for lower kVp settings, whilst maintaining diagnostic attenuation levels. METHODS AND MATERIALS: First, a circulation phantom with physiological parameters (BP 120/80mmHg, HR 60bpm) was used. A fixed CM injection protocol was used for each kVp setting (300mgI/ml [Iopromide], volume=45ml, flow rate=6.0ml/s, iodine delivery rate [IDR]=1.8gI/s, iodine load=13.5gI; at 120, 100, 80 and 70kVp). Then, IDR was decreased by steps of 0.2gI/s for each kVp setting, until diagnostically insufficient attenuation values were reached (<325HU). In order to keep injection time constant (7.5s), total iodine load (TIL) was reduced accordingly. Second, clinical applicability at 120 and 100kVp was evaluated in patients (n=60) referred for coronary CT angiography. A standard and reduced (12% less) CM protocol was used based on weight classes and scan duration ('high-pitch': 1s; 'adaptive sequence' and 'helical': 7s). Attenuation levels of the coronary arteries were measured and compared between protocols. RESULTS: Using a fixed CM injection at each kVp level resulted in the following HU values: 335HU±31 (120kVp); 425HU±30 (100kVp); 587HU±29 (80kVp); 666HU±27 (70kVp). Keeping diagnostic enhancement levels (353HU±28) CM could be reduced as follows: 12% for 100kVp; 45% for 80kVp and 56% for 70kVp. Diagnostic enhancement levels could be reproduced with concurrent CM reduction (-12% at 100kV) in the clinical setting (382HU±35). CONCLUSION: CM injection parameters can be substantially reduced at low kVp settings (up to 56% at 70kVp), whilst maintaining diagnostic attenuation levels. This may play an important role in CT imaging of the coronary arteries as well as cerebral and peripheral circulations in the future.

Patient Comfort During Contrast Media Injection in Coronary Computed Tomographic Angiography Using Varying Contrast Media Concentrations and Flow Rates: Results From the EICAR Trial.

PURPOSE: Pain sensation and extravasation are potential drawbacks of contrast media (CM) injection during computed tomographic angiography. The purpose was to evaluate safety and patient comfort of higher flow rates in different CM protocols during coronary computed tomographic angiography. METHODS: Two hundred consecutive patients of a double-blind randomized controlled trial (NCT02462044) were analyzed. Patients were randomized to receive 94 mL of prewarmed iopromide 240 mg I/mL at 8.3 mL/s (group I), 75 mL of 300 mg I/mL at 6.7 mL/s (group II), or 61 mL of 370 mg I/mL at 5.4 mL/s (group III), respectively. Iodine delivery rate (2.0 g I/s) and total iodine load (22.5 g I) were kept identical. Outcome was defined as intravascular enhancement, patient comfort during injection, and injection safety, expressed as the occurrence of extravasation. Patients completed a questionnaire for comfort, pain, and stress during CM injection. Comfort was graded using a 5-point scale, 1 representing "very bad" and 5 "very well." Pain was graded using a 10-point scale, 0 representing "no pain" and 10 "severe pain." Stress was graded using a 5-point scale, 1 representing "no stress" and 5 "unsustainable stress." RESULTS: Mean enhancement levels within the coronary arteries were as follows: 437 ± 104 Hounsfield units (HU) (group I), 448 ± 111 HU (group II), and 447 ± 106 HU (group III), with P ≥ 0.18. Extravasation occurred in none of the patients. Median (interquartile range) for comfort, pain, and stress was, respectively, 4 (4-5), 0 (0-0), and 1 (1-2), with P ≥ 0.68. CONCLUSIONS: High flow rates of prewarmed CM were safely injected without discomfort, pain, or stress. Therefore, the use of high flow rates should not be considered a drawback for CM administration in clinical practice.

Individualized CT Angiography Protocols for the Evaluation of the Aorta: A Feasibility Study.

PURPOSE: Ionizing radiation and iodinated contrast media are potential drawbacks to repetitive follow-up CT angiography in current practice. The aim of the present study was to optimize radiation dose and contrast agent volume by using individualized CT angiography protocols. MATERIALS AND METHODS: Eighty consecutive patients referred for CT angiography of the whole aorta were prospectively evaluated. Patients were divided into groups of patients with a body mass index (BMI) < 28 kg/m(2) (group 1; n = 50) and those with a BMI ≥ 28 kg/m(2) (group 2; n = 30). A control group consisted of 50 consecutive patients who were retrospectively evaluated. CT angiography parameters on a second-generation dual-source scanner were 128 × 0.6-mm collimation, pitch of 0.9, rotation time of 0.33 seconds, tube voltages of 80/100/120 kVp (group 1/group 2/control), reference tube current of 400 mA, and image reconstruction at 1-mm/0.8-mm slice thickness (kernels, B30f [control] and I30f/strength 3 [groups 1/2]). The control group received 120 mL of contrast agent (300 mgI/mL) at 4.8 mL/s; groups 1 and 2 received 44 mL and 53 mL at 3.3 mL/s and 4 mL/s, respectively. Effective dose was evaluated for each patient. Image quality was determined by qualitative image analysis at the levels of the thoracic, abdominal, and pelvic aorta as nondiagnostic, diagnostic, good, or excellent, and quantitative image analysis was performed, including attenuation values and contrast-to-noise ratio (CNR). RESULTS: Mean effective radiation dose values for CT angiography of the aorta were 3.7 mSv ± 0.7 in group 1, 6.7 mSv ± 1.4 in group 2, and 8.7 mSv ± 1.9 in the control group (P < .001). Mean attenuation values and CNR levels were 334 HU ± 66 and 16 ± 8, respectively, in group 1, 277 HU ± 56 and 14 ± 5 in group 2, and 305 HU ± 77 and 11 ± 4 in the control group. CONCLUSIONS: Iterative reconstruction algorithms resulted in 23%-57% less radiation in combination with 55%-63% less contrast agent volume compared with standard CT protocols.

Evaluation of individually body weight adapted contrast media injection in coronary CT-angiography.

OBJECTIVES: Contrast media (CM) injection protocols should be customized to the individual patient. Aim of this study was to determine if software tailored CM injections result in diagnostic enhancement of the coronary arteries in computed tomography angiography (CTA) and if attenuation values were comparable between different weight categories. MATERIALS AND METHODS: 265 consecutive patients referred for routine coronary CTA were scanned on a 2nd generation dual-source CT. Group 1 (n=141) received an individual CM bolus based on weight categories (39-59 kg; 60-74 kg; 75-94 kg; 95-109 kg) and scan duration ('high-pitch: 1s; "dual-step prospective triggering": 7s), as determined by contrast injection software (Certegra™ P3T, Bayer, Berlin, Germany). Group 2 (n=124) received a standard fixed CM bolus; Iopromide 300 mgI/ml; volume: 75 ml; flow rate: 7.2 ml/s. Contrast enhancement was measured in all proximal and distal coronary segments. Subjective and objective image quality was evaluated. Statistical analysis was performed using SPSS (IBM, version 20.0). RESULTS: For group 1, mean attenuation values of all segments were diagnostic (>325 HU) without statistical significant differences between different weight categories (p>0.17), proximal vs. distal: 449 ± 65-373 ± 58 HU (39-59 kg); 443 ± 69-367 ± 81 HU (60-74 kg); 427 ± 59-370 ± 61 HU (75-94 kg); 427 ± 73-347 ± 61 HU (95-109 kg). Mean CM volumes were: 55 ± 6 ml (39-59 kg); 61 ± 7 ml (60-74 kg); 71 ± 8 ml (75-94 kg); 84 ± 9 ml (95-109 kg). For group 2, mean attenuation values were not all diagnostic with differences between weight categories (p<0.01), proximal vs. distal: 611 ± 142-408 ± 69 HU (39-59 kg); 562 ± 135-389 ± 98 HU (60-74 kg); 481 ± 83-329 ± 81 HU (75-94 kg); 420 ± 73-305 ± 35 HU (95-109 kg). Comparable image noise and image quality were found between groups (p ≥ 0.330). CONCLUSIONS: Individually tailored CM injection protocols yield diagnostic attenuation and a more homogeneous enhancement pattern between different weight groups. CM volumes could be reduced for the majority of patients utilizing individualized CM bolus application.

Low contrast media volume in pre-TAVI CT examinations.

PURPOSE: To evaluate image quality using reduced contrast media (CM) volume in pre-TAVI assessment. METHODS: Forty-seven consecutive patients referred for pre-TAVI examination were evaluated. Patients were divided into two groups: group 1 BMI < 28 kg/m(2) (n = 29); and group 2 BMI > 28 kg/m(2) (n = 18). Patients received a combined scan protocol: retrospective ECG-gated helical CTA of the aortic root (80kVp) followed by a high-pitch spiral CTA (group 1: 70 kV; group 2: 80 kVp) from aortic arch to femoral arteries. All patients received one bolus of CM (300 mgI/ml): group 1: volume = 40 ml; flow rate = 3 ml/s, group 2: volume = 53 ml; flow rate = 4 ml/s. Attenuation values (HU) and contrast-to-noise ratio (CNR) were measured at the levels of the aortic root (helical) and peripheral arteries (high-pitch). Diagnostic image quality was considered sufficient at attenuation values > 250HU and CNR > 10. RESULTS: Diagnostic image quality for TAVI measurements was obtained in 46 patients. Mean attenuation values and CNR (HU ± SD) at the aortic root (helical) were: group 1: 381 ± 65HU and 13 ± 8; group 2: 442 ± 68HU and 10 ± 5. At the peripheral arteries (high-pitch), mean values were: group 1: 430 ± 117HU and 11 ± 6; group 2: 389 ± 102HU and 13 ± 6. CONCLUSION: CM volume can be substantially reduced using low kVp protocols, while maintaining sufficient image quality for the evaluation of aortic root and peripheral access sites. KEY POINTS: • Image quality could be maintained using low kVp scan protocols. • Low kVp protocols reduce contrast media volume by 34-67 %. • Less contrast media volume lowers the risk of contrast-induced nephropathy.

Individually tailored contrast enhancement in CT pulmonary angiography.

OBJECTIVE: The purpose was to evaluate individually shaped contrast media (CM) delivery in CT pulmonary angiography (CTPA) for suspected pulmonary embolism (PE). METHODS: 100 consecutive emergency patients with clinical suspicion of PE were evaluated. High-pitch CTPA was performed on a second-generation dual-source CT using the following parameters: 100 kV, 200-250 mAsref, rotation time 0.28 s, 128 × 0.6 mm col. and image reconstruction 1.0/0.8 mm (B30f). Group 1 (n = 50) then received a fixed CM bolus (300 = mgI ml(-1), volume = 90 ml and flow rate = 6 ml s(-1)); Group 2 (n = 50) received a body weight-adapted CM bolus determined by dedicated contrast injection software. For analysis, groups were further subdivided into low-weight (40-75 kg) and high-weight (76-117 kg) groups. Technical image quality was graded using a four-point Likert scale (1 = non-diagnostic; 2 = diagnostic; 3 = good and 4 = excellent image quality) at the level of the pulmonary trunk and pulmonary arteries. Objective image quality analysis was performed by measuring contrast enhancement in Hounsfield units (HU) at the same levels. Attenuation levels > 180 HU were considered diagnostic. RESULTS: All examinations were graded as diagnostic at each level. The individual minimum pulmonary attenuation was 184 and 270 HU for Group 1 and 2, respectively. Mean attenuation was as follows: Group 1: 475 ± 105 HU (40-75 kg) and 402 ± 115 HU (76-117 kg), p < 0.03. Group 2: 424 ± 76 HU (40-75 kg) and 418 ± 100 HU (76-117 kg), p = 0.8. For Group 2, CM volumes were: 55 ± 5 ml (40-75 kg) and 66 ± 5 ml (76-117 kg), leading to 16-51% CM reduction. CONCLUSION: Even under emergency conditions, individualized CM protocols can provide diagnostic and robust image quality in CTPA for PE with a substantial reduction of CM volume for lower weight patients, compared with a fixed CM protocol. ADVANCES IN KNOWLEDGE: CM volume can substantially be reduced by using individualized CM protocols in CT angiography for PE without compromising the diagnostic image quality.

Automated Tube Voltage Selection for Radiation Dose Reduction in CT Angiography Using Different Contrast Media Concentrations and a Constant Iodine Delivery Rate.

OBJECTIVE: The purpose of this study was to systematically investigate radiation dose reduction using automated tube voltage selection during CT angiography (CTA) and to evaluate the impact of contrast medium (CM) injection protocols on dose reduction. MATERIALS AND METHODS: A circulation phantom containing the thoracic and abdominal vasculature was used. Four different concentrations of CM (iopromide 300 and 370 mg I/mL and iomeprol 350 and 400 mg I/mL) were administered while maintaining an identical iodine delivery rate (1.8 g I/s) and total iodine load (20.0 g). Three different scanning protocols for CTA of the thoracoabdominal aorta were used: protocol A, no dose modulation; protocol B, automated tube current modulation (CARE Dose4D); and protocol C, automated tube voltage selection (CARE kV). The dose-length product was recorded to calculate the effective dose. Attenuation values (in Hounsfield units), image noise levels, and signal-to-noise ratios (SNRs) in six predefined intravascular sites (three thoracic and three abdominal) were measured by two readers. All values were analyzed using the Kruskal-Wallis test and two-way ANOVA. RESULTS: There was a significant reduction in the effective dose (in millisieverts) for protocols B (mean ± SD, 2.03 ± 0.1 mSv) and C (1.00 ± 0.0 mSv) compared with protocol A (4.34 ± 0.0 mSv). The dose was reduced by 53% for protocol B and by 77% for protocol C. No significant differences were found in the effective dose among the different CM injection protocols within the scanning protocols; all p values were > 0.05. The attenuation values and SNRs were comparable among all the different CM injection protocols; all p values were > 0.05. CONCLUSION: A large radiation dose reduction (77%) can be achieved using automated tube voltage selection independent of the CM injection protocol.

Coronary CT angiography using low concentrated contrast media injected with high flow rates: Feasible in clinical practice.

PURPOSE: Aim of this study was to test the hypothesis that peak injection pressures and image quality using low concentrated contrast media (CM) (240 mg/mL) injected with high flow rates will be comparable to a standard injection protocol (CM: 300 mg/mL) in coronary computed tomographic angiography (CCTA). MATERIAL AND METHODS: One hundred consecutive patients were scanned on a 2nd generation dual-source CT scanner. Group 1 (n=50) received prewarmed Iopromide 240 mg/mL at an injection rate of 9 mL/s, followed by a saline chaser. Group 2 (n=50) received the standard injection protocol: prewarmed Iopromide 300 mg/mL; flow rate: 7.2 mL/s. For both protocols, the iodine delivery rate (IDR, 2.16 gI/s) and the total iodine load (22.5 gI) were kept identical. Injection pressure (psi) was continuously monitored by a data acquisition program. Contrast enhancement was measured in the thoracic aorta and all proximal and distal coronary segments. Subjective and objective image quality was evaluated between both groups. RESULTS: No significant differences in peak injection pressures were found between both CM groups (121 ± 5.6 psi vs. 120 ± 5.3 psi, p=0.54). Flow rates of 9 mL/s were safely injected without any complications. No significant differences in contrast-to-noise ratio, signal-to-noise ratio and subjective image quality were found (all p>0.05). No significant differences in attenuation levels were found in the thoracic aorta and all segments of the coronary arteries (all p>0.05). CONCLUSION: Usage of low iodine concentration CM and injection with high flow rates is feasible. High flow rates (9 mL/s) of Iopromide 240 were safely injected without complications and should not be considered a drawback in clinical practice. No significant differences in peak pressure and image quality were found. This creates a doorway towards applicability of a broad variety in flow rates and IDRs and subsequently more individually tailored injection protocols.

Contrast Enhancement of the Right Ventricle during Coronary CT Angiography--Is It Necessary?

PURPOSE: It is unclear if prolonged contrast media injection, to improve right ventricular visualization during coronary CT angiography, leads to increased detection of right ventricle pathology. The purpose of this study was to evaluate right ventricle enhancement and subsequent detection of right ventricle disease during coronary CT angiography. MATERIALS AND METHODS: 472 consecutive patients referred for screening coronary CT angiography were retrospectively evaluated. Every patient underwent multidetector-row CT of the coronary arteries: 128x 0.6mm coll., 100-120kV, rot. time 0.28s, ref. mAs 350 and received an individualized (P3T) contrast bolus injection of iodinated contrast medium (300 mgI/ml). Patient data were analyzed to assess right ventricle enhancement (HU) and right ventricle pathology. Image quality was defined good when right ventricle enhancement >200HU, moderate when 140-200HU and poor when <140HU. RESULTS: Good image quality was found in 372 patients, moderate in 80 patients and poor in 20 patients. Mean enhancement of the right ventricle cavity was 268HU±102. Patients received an average bolus of 108±24 ml at an average peak flow rate of 6.1±2.2 ml/s. In only three out of 472 patients (0.63%) pathology of the right ventricle was found (dilatation) No other right ventricle pathology was detected. CONCLUSION: Right ventricle pathology was detected in three out of 472 patients; the dilatation observed in these three cases may have been picked up even without dedicated enhancement of the right ventricle. Based on our findings, right ventricle enhancement can be omitted during screening coronary CT angiography.