Dose Of Contrast Agent Research Articles

Contrast-induced encephalopathy following endovascular treatment for intracranial aneurysms-risk factors analysis and clinical strategy.

Contrast-induced encephalopathy (CIE) was defined as new onset of neurological deficits after exposure to contrast media, which could be observed after the endovascular treatment for intracranial aneurysms. We enrolled a consecutive cohort of patients who underwent endovascular treatment for unruptured intracranial aneurysms. CIE was defined as a reversible neuropathic syndrome that occurred after interventional therapy, accompanied by imaging abnormalities and excluding other diseases. Multivariable Poisson regression analysis was performed to show risk factors by incidence rate ratio (IRR) and a clinical strategy was proposed. Among the 579 patients who underwent interventional therapy for intracranial aneurysms, the crude incidence rate of CIE was 2.4% (95% CI, 1.2-3.6%) at our center. Headache, hemiplegia, and disorientation could be initial symptoms, and cortical blindness was the most common localized deficit. Cerebral edema and sulci effacement on CT were observed, and re-revaluation after treatments on CT/MRI showed absent lesions. The risk factors were history of stroke (IRR, 7.752; P = 0.007), history of hypertension (IRR, 1.064; P = 0.042), posterior circulation aneurysms (IRR, 9.412; P = 0.004) and higher dosage of contrast agents (IRR, 1.018; P = 0.007). After the strategy of accelerating excretion of contrast agents, reduction of intracranial pressure and anti-inflammation/vasospasm therapy, the prognosis was favorable with most patients fully recovered within 72h. History of stroke and posterior circulation aneurysms were main risk factors for CIE. A higher dosage of contrast agents might induce CIE, and the history of hypertension should be considered as well.

Intravascular US: Applications in Interventional Radiology.

Interventional radiology applications of intravascular US (IVUS) continue to expand, complementing intraprocedural angiography and providing a unique vantage from which to guide endovascular interventions. Vascular pathologic conditions become sonographically visualized rather than inferred from the planar appearance of the opacified vascular lumen. Perivascular targets become sonographically visualized rather than approximated on the basis of fluoroscopic landmarks. The authors introduce broad categories of IVUS catheters, namely radial and side-firing varieties, as well as prevailing options for each and their technical specifications. Common applications within interventional radiology are covered in a systems approach, including deep venous thrombosis, May-Thurner syndrome, nutcracker syndrome, transjugular intrahepatic portosystemic shunts, aortic interventions, peripheral arterial disease, and endovascular or perivascular biopsy. Discussions are accompanied by technical pearls from the authors, and summarized evidence where IVUS has been shown to reduce procedural time, intravascular contrast agent dose, radiation exposure, and morbidity in each space is presented. Finally, emerging applications and future directions are discussed. ©RSNA, 2022.

Ratlarda intravenöz kontrast madde uygulamasının göz içi basıncı, göz yaşı miktarı ve oksidatif stres üzerine etkileri

Although iodinated radiocontrast agents, which are frequently used in radiological procedures such as indirect radiography, angiography, intravenous urography and computed tomography, are generally safe, they can cause serious side effects. In this study, it was aimed to investigate the effect of intravenous ionic high osmolar contrast agent administration on intraocular pressure, tear amount and oxidant and antioxidant parameters of eye tissue. Study groups consisted of 2 groups, Group 1 (Control) and Group 2 (Urographin), and a total of 16 Wistar albino female rats were used. On the first day of the experiment, 6 ml/kg of physiological saline was administered intravenously to the control group, and the same dose of contrast agent was administered to group 2. Intraocular pressure and tear amounts were measured at 1, 6, 12, 24 and 48 hours after intravenous administration. After measurements were made at the 48th hour of the experiment, all rats were euthanized and their eye tissues were removed. In order to reveal the oxidative damage and antioxidant activity in the eye tissue, malondialdehyde and reduced glutathione levels, catalase and glutathione peroxidase enzyme activities were measured spectrophotometrically. Schimer tear test (STT-1) strip was used for tear amount measurements, and rebound tonometer Tonovet® was used as tonometer for intraocular pressure measurements. No statistically significant difference was found between the control and urographin groups in terms of intraocular pressure and tear amounts in the measurements performed at 1,6,12,24 and 48th hours after urographin administration. It was observed that the same application significantly increased the malondialdehyde level (P<0.005) in the eye tissue. There was no significant difference between the groups in terms of reduced glutathione level and catalase and glutathione peroxidase enzyme activities in eye tissue. It was evaluated that intravenous contrast agent administration causes oxidative stress in the eye tissue and this may have a long-term ocular effect

Transradial versus transfemoral access without closure device for transarterial chemoembolization in patients with hepatocellular carcinoma: a randomized trial.

To compare patient satisfaction, procedural variables, and safety with transradial access (TRA) and transfemoral access (TFA) in patients undergoing transarterial chemoembolization (TACE) for hepatocellular carcinoma (HCC). From February 2019 to August 2021, 130 patients undergoing TACE for HCC were randomly allocated to the TRA (n = 65) or TFA (n = 65) group. Vascular closure devices were not used after TFA-TACE. All patients completed the post-catheterization questionnaire and 8-item Short-Form Health Survey 1 day after TACE. Technical success rate, crossover rate, contrast agent dose, fluoroscopy time, procedure time, air kerma, dose-area product, length of hospital stay, and total cost were similar between the two groups (all p > 0.05). The incidence and severity of adverse events were also similar between the two groups (all p > 0.05). However, overall discomfort, difficulty going to the bathroom, difficulty feeding or self-caring, difficulty walking, general health, physical function, role physical function, social function, mental health, and role emotional function were better in the TRA group than in the TFA group (all p < 0.001). Consequently, more patients preferred the current access for their next procedure in the TRA group than in the TFA group (90.8% vs. 24.6%; p < 0.001). In patients undergoing TACE for HCC, using TRA instead of TFA can improve patient satisfaction without compromising procedural variables and safety. • Transradial access (TRA) enabled early ambulation after transarterial chemoembolization (TACE), resulting in significant increase in activities of daily living and health-related quality of life (HRQoL) compared to transfemoral access (TFA) when vascular closure devices were not used. • Procedural variables (contrast agent dose, fluoroscopy time, procedure time, air kerma, dose-area product, length of hospital stay, and total cost) were not significantly different between patients who received TRA-TACE and TFA-TACE. • The incidence and severity of adverse events were similar between patients who received TRA-TACE and TFA-TACE.

Fabrication and Pulse Sequences Evaluation of Iron Oxides Nanoparticles as MRI Contrast Agent

The objective of this in vivo study is to enhance the T2-weighted MRI contrast using superparamagnetic nanoparticles in liver and spleen of rabbits for biomedicine application. Superparamagnetic nanoparticles were synthesized using co-precipitation method. Superparamagnetic nanoparticles were characterized using SEM, EDX, VSM, magnetic resonance relaxation and magnetic resonance imaging (MRI). T1 and T2 relaxations were measured as function of concentration of contrast agents in liver and spleen. High relaxivity ratio r2/r1 showed the efficacy of prepared T2- weighted MRI contrast agent. Rabbits were anesthetized using xylazine and ketamine salts for medical procedure. Ketamine and xylazine were injected with the dose rate of ketamine 25-40 mg/kg and xylazine 2.5-5mg/kg intra-muscularly for veterinary anesthesia. MRI of albino rabbits was executed at 0.35 Tesla using magnetic nanoparticles. FDA approved, 0.2 ml/kg dose of contrast agents was injected in rabbits for MRI scanning. MRI axial and coronal, T1-W and T2-W images of liver and spleen were taken using Spin Echo (SE) at TE=92 and TR=551 and STIR at TE=24 and TR=5170. Spin software was used to estimate the intensity of signal in region of interest induced by magnetic contrast agent. In vivo, MRI study of magnetic contrast agents demonstrated the high T2 -weighted contrast on MRI images of liver and spleen of rabbits. This research also concludes that superparamagnetic nanoparticles may be used as MRI contrast agents for biomedicine application to see the pathology of living organs even at low tesla field.

Red blood cell distribution width-to-albumin ratio: a new inflammatory biomarker to predict contrast-induced nephropathy after emergency percutaneous coronary intervention.

Contrast-induced nephropathy (CIN) remains a dreaded complication in the cardiac diagnostic and interventional area. We investigated the relationship between red blood cell distribution width-to-albumin ratio (RAR) and CIN in elderly patients with ST-segment elevation myocardial infarction (STEMI) undergoing emergency percutaneous coronary intervention (PCI). A total of 1532 elderly patients were enrolled and divided into the CIN group and the non-CIN group. The risk factors of CIN were evaluated by univariate and multivariate regression analysis. Receiver-operating characteristic (ROC) curve analysis was used to identify the best predictive value. CIN occurred in 129 (8.42%) patients. Patients in the CIN group had significantly higher RAR than those in the non-CIN group (4.69 ± 0.73 vs. 3.18 ± 0.64, P < 0.001). In multivariate regression analysis, RAR was an independent risk factor for the development of CIN (OR: 1.506, 95% CI: 1.227-2.083, P = 0.025), along with age, creatinine, eGFR, hs-CRP and contrast agent dose. The AUC of RAR was 0.755 (95% CI 0.703-0.807), and an optimal cutoff value of 3.64 or higher predicted CIN with a sensitivity of 76.2% and specificity of 65.7%. As a combined inflammatory-related index, RAR was an independent risk factor for the development of CIN in elderly patients with STEMI undergoing emergency PCI. The RAR could be a simple but relatively reliable parameter for identifying high-risk patients.

Clinical Application of "Three-Low" Technique Combined with Artificial Intelligence Iterative Reconstruction Algorithm in Aortic CT Angiography

To explore the application value of the "three-low" technique (low radiation dose, low contrast agent dosage and low contrast agent flow rate) combined with artificial intelligence iterative reconstruction (AIIR) in aortic CT angiography (CTA). A total of 33 patients who underwent aortic CTA were prospectively enrolled. Based on the time of their follow-up examinations, the imaging data were divided into Group A and Group B, with Group A being the control group (100 kV, 0.8 mL/kg, 5 mL/s) and Group B being the "three-low" technique group (70 kV, 0.5 mL/kg, 3 mL/s). In group A, the images were reconstructed by Karl iterative algorithm. Group B was divided into B1 and B2 subgroups, with their images being reconstructed by Karl iterative algorithm and AIIR, respectively. The CT and SD values of the ascending aorta, descending aorta, abdominal aorta, left common iliac artery and right common iliac artery were measured, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The subjective scoring of image quality was performed. The radiation dose parameters were documented. Differences in the CT value, SD value, SNR and CNR of the three groups were statistically significant ( P<0.001). The CT value, SNR and CNR of group B2 were significantly higher than those of group B1, while the SD value of group B2 was significantly lower than that of group B1 ( P<0.017). There was no significant difference between the CT values of group A and those of group B2 ( P>0.017). The SD values, SNR and CNR in group B2 were better than those in group A ( P>0.017). There was significant difference in the subjective evaluation of image quality among the three groups ( P<0.05), but there was no significant difference between group A and group B2 ( P>0.017). The radiation dose and contrast medium dosage in group B decreased 84.14% and 37.08%, respectively, compared with those of group A. With the "three-low" technique combined with AIIR algorithm, the image quality of aortic CTA obtained is comparable to that of conventional dose scanning, while the radiation dose, contrast agent dosage and contrast agent flow rate of patients are significantly reduced.

Perfusion Maps Acquired From Dynamic Angiography MRI Using Deep Learning Approaches.

A typical stroke MRI protocol includes perfusion-weighted imaging (PWI) and MR angiography (MRA), requiring a second dose of contrast agent. A deep learning method to acquire both PWI and MRA with single dose can resolve this issue. To acquire both PWI and MRA simultaneously using deep learning approaches. Retrospective. A total of 60 patients (30-73 years old, 31 females) with ischemic symptoms due to occlusion or ≥50% stenosis (measured relative to proximal artery diameter) of the internal carotid artery, middle cerebral artery, or anterior cerebral artery. The 51/1/8 patient data were used as training/validation/test. A 3 T, time-resolved angiography with stochastic trajectory (contrast-enhanced MRA) and echo planar imaging (dynamic susceptibility contrast MRI, DSC-MRI). We investigated eight different U-Net architectures with different encoder/decoder sizes and with/without an adversarial network to generate perfusion maps from contrast-enhanced MRA. Relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), mean transit time (MTT), and time-to-max (Tmax ) were mapped from DSC-MRI and used as ground truth to train the networks and to generate the perfusion maps from the contrast-enhanced MRA input. Normalized root mean square error, structural similarity (SSIM), peak signal-to-noise ratio (pSNR), DICE, and FID scores were calculated between the perfusion maps from DSC-MRI and contrast-enhanced MRA. One-tailed t-test was performed to check the significance of the improvements between networks. P values < 0.05 were considered significant. The four perfusion maps were successfully extracted using the deep learning networks. U-net with multiple decoders and enhanced encoders showed the best performance (pSNR 24.7 ± 3.2 and SSIM 0.89 ± 0.08 for rCBV). DICE score in hypo-perfused area showed strong agreement between the generated perfusion maps and the ground truth (highest DICE: 0.95 ± 0.04). With the proposed approach, dynamic angiography MRI may provide vessel architecture and perfusion-relevant parameters simultaneously from a single scan. 3 TECHNICAL EFFICACY: Stage 5.

Effect of Contrast Agent Dose Reduction on Vascular Enhancement and Image Quality in Thoracoabdominal Dynamic 3-Dimensional Magnetic Resonance Angiography: A Systematic Intraindividual Analysis in Pigs.

High spatial and temporal resolution contrast-enhanced magnetic resonance angiography (MRA) with gadolinium-based contrast agents (GBCAs) at standard dose offers both detailed anatomic information on both arterial and venous vessels and hemodynamic characteristics. Several preclinical and clinical dynamic 3-dimensional (3D) MRA studies that focused on arterial vessels only proposed that high image quality may also be achieved with significantly reduced GBCA doses, calling into question the need to use standard doses. A systematic analysis of GBCA doses and resulting image quality for both arteries and veins has not yet been performed. The purpose of this study was therefore to systematically analyze dose-dependent vascular enhancements in dynamic 3D-MRA of the thoracoabdominal vasculature at 1.5 T in an animal model to determine the optimal contrast agent protocol for optimized vascular assessment. The vascular enhancement in thoracoabdominal dynamic 3D-MRA (time-resolved angiography with interleaved stochastic trajectories, TWIST at 1.5 T) was interindividually and intraindividually compared in 5 anesthetized Göttingen minipigs using gadobutrol at the standard dose (0.1 mmol/kg body weight, ie, 0.1 mL/kg) and at reduced doses (0.08, 0.06, 0.04, 0.02 mmol/kg) in a randomized order. All injections were performed at 2 mL/s followed by 20 mL saline. Images were quantitatively analyzed, measuring signal intensities in 5 regions that covered the passage of the GBCA through the body at different representative stages of circulation (pulmonary, arterial, and venous system). The evaluation of GBCA dose-dependent signal intensity changes in the different vascular regions was performed by linear regression analysis.The qualitative image analysis of dynamic 3D-MRA by 3 independent radiologists included the visibility of 25 arterial and venous vessel segments at different stages of GBCA passage. Possible quality losses were statistically tested by comparing image quality ratings at the reduced dose with that of the standard dose using Friedman test followed by Dunn post hoc test for multiple comparison. Significance was stated at P < 0.05. Quantitative analysis revealed shorter time-to-peak intervals and bolus durations in line with decreasing GBCA dose and volume in all vessels. Although the peak signal was almost independent of the administered GBCA dose at the level of the pulmonary trunk, a linear signal decrease in the abdominal aorta ( r2 = 0.96), the renal arteries ( r2 = 0.99), the inferior vena cava ( r2 = 0.99), and the portal vein ( r2 = 0.97) was observed. Cumulative analysis of arterial segments revealed significantly lower image quality at doses below 40% of the standard dose, whereas in venous segments, significantly lower image quality was observed at doses below 60% of the standard dose. In dynamic 3D-MRA at 1.5 T, dose reduction leads to a signal loss that is most pronounced in the venous system and results in significantly lower image quality according to the dose and vessels of interest. Careful dose reduction is thus required according to the specific diagnostic needs. For dynamic 3D-MRA of the arterial and venous system, GBCA doses of at least 60% of the standard dose up to the full dose are preferable, whereas 40% of the standard dose seems feasible if only the arterial system is to be imaged.

Is Hysterosalpingo-Contrast Sonography (HyCoSy) Using Sulfur Hexafluoride Microbubbles (SonoVue) Sufficient for the Assessment of Fallopian Tube Patency? A Systematic Review and Meta-Analysis.

This study aimed to evaluate the diagnostic value of HyCoSy using sulfur hexafluoride microbubbles for fallopian tubal patency assessment in infertile females. Twenty-four studies, including 1358 females with 2661 detected fallopian tubes published from January 2003 to May 2019, were identified. The pooled sensitivity was 93% (95% CI: 90-95%), while the specificity was 90% (95% CI: 87-92%). The area under the receiver-operating characteristic curve was 0.96 (95% CI: 94-98%). The specificity of the four-dimensional HyCoSy subgroup was higher than the 2D/3D subgroup; an increased dose of contrast agent did not affect the specificity, with only a slightly reduced sensitivity.

Radiation dose reduction during adrenal vein sampling using a new angiographic imaging technology

To compare the patient radiation doses during angiographic selective adrenal vein sampling (AVS) before and after an imaging technology upgrade. In this retrospective single-center-study, cumulative air kerma (AK), cumulative dose area product (DAP), fluoroscopy time and contrast agent dosage were recorded from 70 patients during AVS. 35 procedures were performed before and 35 after an imaging processing technology upgrade. Mean values were calculated and compared using an unpaired student’s t-test. DSA image quality was assessed independently by two blinded readers using a four-point Likert scale (1 = poor; 4 = excellent) and compared using Wilcoxon signed-rank test. After the technology upgrade we observed a significant reduction of 35% in AK (1.7 ± 0.7 vs. 1.1 ± 0.7 Gy, p = 0.01) and a significant reduction of 28% in DAP (235.1 ± 113 vs. 170.1 ± 94 Gy*cm2, p = 0.01) in comparison to procedures before the upgrade. There were no significant differences between the number of exposure frames (143 ± 86 vs. 132 ± 61 frames, p = 0.53), fluoroscopy time (42 ± 23 vs. 36 ± 18 min, p = 0.22), or the amount of contrast medium used (179.5 ± 84 vs. 198.1 ± 109 ml, p = 0.41). There was also no significant difference regarding image quality (3 (2–4) vs. 3 (2–4), p = 0.67). The angiographic imaging technology upgrade significantly decreases the radiation dose during adrenal vein sampling without increasing time of fluoroscopy or contrast volume and without compromising image quality.

Influence of Contrast Agent Injection Scheme Customized by Dual-Source CT Based on Automatic Tube Voltage Technology on Image Quality and Radiation Dose of Coronary Artery Imaging.

ObjectiveTo explore the influence of a contrast agent injection scheme customized by dual-source CT based on automatic tube voltage technology on coronary imaging image quality and radiation dose.MethodsA total of 205 patients who underwent coronary CT angiography (CCTA) in our hospital from June 2021 to September 2021 were selected. 105 patients in the control group who underwent routine scanning according to body mass (BMI) and 100 patients in the observation group who set tube voltage and contrast agent dosage according to automatic tube voltage selection technology. CT values of the aortic root (AO); left anterior descending (LAD) branch; proximal, middle, and distal segments of the right coronary artery (RCA); and proximal and distal segments of left circumflex (LCX) branch were measured. We calculated the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the image. Image quality scoring and effective dose (ED) calculation were carried out.ResultsThere was no significant difference in the CT value, SNR value, and CNR value of each part of the artery between the two groups (P > 0.05). Image quality scores of the control group and the observation group were 1.28 ± 0.25 and 1.25 ± 0.23, respectively, and there was no significant difference in scores (P > 0.05). In the control group, the dosage of comparator was 43.81 ± 6.74 ml, and the ED was 4.92 ± 1.26 mSv. The dosage of contrast agent in the observation group was 34.23 ± 6.39 ml, and ED was 3.05 ± 0.94 mSv. The dosage of contrast agent and ED in the observation group were lower than those in the control group (P < 0.05).ConclusionThe contrast agent injection scheme customized by dual-source CT based on automatic tube voltage technology can meet the clinical requirements of coronary image quality, reduce the radiation dose and contrast agent consumption, and help doctors choose a more accurate and reasonable examination scheme, which has certain clinical application value.

Studies on the use of iodine-containing contrast agent diatrizoate in rabbits (Oryctolagus cuniculus)

The use of the iodine-containing contrast agent diatrizoate was investigated in healthy rabbits and in rabbits with gastric dilatation and intestinal obstruction. For this purpose, transit times through the gastrointestinal tract and clinical use were investigated during a one year period. In addition, a possible influence on thyroid hormone levels was evaluated. Transit times of contrast agent through the different intestinal sections were examined radiographically in 14 healthy rabbits. For this purpose, 7 ml/kg of a 300 mg iodine/ml and 600 mg diatrizoate/ml containing solution were administered. Radiographs were obtained at different time intervals. Three different doses (D1 2 ml/kg, D2 7 ml/kg, D3 10 ml/kg) were administered, and blood samples were collected at two time points (60 min, 24 h) to analyze thyroid hormone levels (TT4, fT4, TSH). In addition, 70 rabbits that had received the contrast agent diatrizoate because of gastric dilatation and suspected intestinal obstruction were retrospectively evaluated during a period of one year. Focus was placed on arrival of the contrast agent in the cecum, laboratory changes, and mortalities. In all healthy rabbits, contrast medium was detectable in the cecum after a mean of 45-60 min. In the animals suffering from gastrointestinal obstruction, this was delayed to a mean of 121.2 min. These animals showed hypothermia in 92.4 % and hyperglycemia in 45.9 %. 56.1 % exhibited an increase in urea and 33.9 % an increase in creatinine. In 71.4 % of cases, medical treatment was possible, however 12 % of these individuals succumbed to the disease. 28.6 % of the cases were managed surgically which was associated with a mortality of 50 %. TT4, fT4, and TSH levels displayed significant alterations among the three contrast agent doses (p < 0.05). These changes were found to be transient when follow-up was performed two weeks later. When ileus is suspected in rabbits, diatrizoate may be helpful in evaluating the progression of the disease in addition to the use of native radiographs. Sufficient hydration and monitoring of renal function are advisable. Transient changes in thyroid hormones were evident but lacked clinical relevance.

Association between cine CMR-based radiomics signature and microvascular obstruction in patients with ST-segment elevation myocardial infarction.

BackgroundIn the process of percutaneous coronary intervention (PCI), patients with ST-segment elevation myocardial infarction (STEMI) may receive large doses of the iodine contrast agent. Some adverse events may be aroused if the patients receive the gadolinium agents. We investigate the association between cine cardiac magnetic resonance (CMR)-based radiomics signature and microvascular obstruction (MVO) in patients with STEMI.MethodsA total of 116 STEMI patients who received continuous CMR within 6 days after PCI were retrospectively included in this study. According to the late gadolinium enhancement (LGE) of CMR, the myocardial infarction (MI) was divided into with and without MVO. Radiomic features were extracted from cine CMR images and the least absolute shrinkage and selectionator operator (LASSO) algorithm was used for features selection and radiomic signatures construction. Binary logistic regression was used to assess association between radiomic signatures and MVO with adjusted for baseline clinical characteristics.ResultsOf 116 patients with STEMI, MI with MVO was found in 50 patients and MI without MVO was found in 66 patients. LASSO regression selected five radiomics features for radiomics signature construction. Logistic regression revealed that radiomics score, high sensitivity C-reactive protein (hs-CRP) and creatine phosphokinases (CPK) were independent risk factors for MVO with odds ratio (OR) of 4.41 (95% CI: 2.26–9.93), 1.018 (95% CI: 1.006–1.034) and 1.0007 (95% CI: 1.0004–1.0012), respectively. Area under curve (AUC) of receiver operating characteristic (ROC) of radiomics score to predict MVO was 0.75 (95% CI: 0.68–0.85).ConclusionsCine CMR-based radiomics signature was an independent predictive factor of MVO in patients with STEMI, which showed the potential of this contrast free radiomics signature to be an imaging biomarker for MVO.

Dual-layer spectral detector CT for contrast agent concentration, dose and injection rate reduction: Utility in imaging of the superior mesenteric artery

PurposeTo investigate the feasibility of contrast agent and injection rate reduction for dual-layer spectral detector computed tomography (SDCT) imaging of the superior mesenteric artery (SMA) using virtual monochromatic image (VMI). MethodsA total of 102 patients who underwent abdominal arterial phase-enhanced SDCT examination due to suspected abdominal diseases were prospectively selected and divided into control group, low concentration/dose groups (groups 370-0.7, 300-1.0, and 300-0.9) and low injection rate groups (groups 2-370 and 2-350). Compared with the control group, low concentration/dose groups and low injection rate groups lowered the concentration/dose or injection rate of the contrast agent to varying degrees. The raw data obtained in each group were reconstructed using hybrid-iterative reconstruction and projection spatial-spectral reconstruction algorithm. The image quality of the SMA in conventional images (CI) and in VMIs40-140 kiloelectron volt (keV) (interval: 10 keV) during the arterial phase was analyzed. Multiplanar reformation images and volume rendering images of the SMA were reconstructed. Image quality objective evaluation indexes included the CT values, contrast-to-noise ratio, signal-to-noise ratio, and diameter of the SMA. The diameter of the SMA was determined by the CT values profile curve and its full width at half maximum. Two doctors independently evaluated the subjective image quality of multiplanar reformation coronal images and volume rendering images according to a 5-point scale. Repeated analysis of variance and Friedman test were used to compare the differences in the objective evaluation indexes and subjective scores between VMIs and CI in the same group. The Dunnett’s t-test or Dunnett’s T3 test and Kruskal-Wallis H-test were used to compare the differences in the objective evaluation indexes and subjective scores between the experimental and control groups. ResultsVMIs of the SMA in each group had the best image quality at 60 keV, and VMI60 keV in each group were better than their respective CI to varying degrees. Although the objective (CT values, contrast-to-noise ratio, and signal-to-noise ratio) and subjective (subjective scores) indexes of CI in the low concentration/dose groups and low injection rate groups were lower than those of CI in the control group to varying degrees, these indexes of VMI60 keV in the low concentration/dose groups and group 2-370 were equal to or even better than the CI in the control group. ConclusionsVMI60 keV using SDCT could effectively reduce the contrast agent load while providing equivalent or better SMA image quality compared with CI obtained using a conventional contrast agent protocol. When the injection rate was lowered to 2.0 ml/s for a high-concentration contrast agent (370 mgI/ml), the SMA image quality at VMI60 keV was comparable with that of the CI in the control group.

The impact of imaging time and contrast agent dose on screening for osteoporosis with contrast-enhanced CT

BackgroundScreening for osteoporosis with contrast-enhanced computed tomography (CT) is promising for identifying high-risk osteoporotic patients. Our aims were (1) to investigate the estimated volume bone mineral density (vBMD) change over time after contrast injection (CT perfusion imaging, CTPI); and (2) to examine the influence of contrast dose on vBMD.MethodsFifteen patients, aged 71 ± 9 years (mean ± standard deviation, range 55–86) underwent a CTPI examination (28 scans within 63 s) of the upper body followed (after a waiting time of 10 min) by a full 4-phase CT examination (4 scans within 4 min). The contrast dose for CTPI was 0.38–0.83 mL/kg, and for 4-phase CT was 0.87–1.29 mL/kg. Vertebrae L1–L3 were analysed totalling 43 vertebrae, using Mindways qCT Pro.ResultsAfter contrast injection, vBMD showed a near-horizontal line until 17.5 s (non-contrast phase), followed by a steep increase 17.5–41.5 s after contrast injection, i.e., in the arterial phase, which plateaued 41.5 s after, i.e., in the early venous phase. A higher contrast dose per kg yielded significantly higher vBMD increase in both the arterial and venous phase (p < 0.003).ConclusionsBoth time from contrast administration and contrast dose per kg affected vBMD results. In arterial phase, the steepness of the curve makes vBMD estimation unsure. However, as values plateaued in the venous phase it might be possible to predict the correct vBMD values. Furthermore, contrast dose is a factor that needs to be adjusted for when using such a formula.

Simultaneous Image Reconstruction and Element Decomposition for Iodine Contrast Agent Visualization in Multienergy Element-Resolved Cone Beam CT.

Iodine contrast agent is widely used in liver cancer radiotherapy at CT simulation stage to enhance detectability of tumor. However, its application in cone beam CT (CBCT) for image guidance before treatment delivery is still limited because of poor image quality and excessive dose of contrast agent during multiple treatment fractions. We previously developed a multienergy element-resolved (MEER) CBCT framework that included x-ray projection data acquisition on a conventional CBCT platform in a kVp-switching model and a dictionary-based image reconstruction algorithm that simultaneously reconstructed x-ray attenuation images at each kilovoltage peak (kVp), an electron density image, and elemental composition images. In this study, we investigated feasibility using MEER-CBCT for low-concentration iodine contrast agent visualization. We performed simulation and experimental studies using a phantom with inserts containing water and different concentrations of iodine solution and the MEER-CBCT scan with 600 projections in a full gantry rotation, in which the kVp level sequentially changed among 80, 100, and 120 kVps. We included iodine material in the dictionary of the reconstruction algorithm. We analyzed iodine detectability as quantified by contrast-to-noise ratio (CNR) and compared results with those of CBCT images reconstructed by the standard filter back projection (FBP) method with 600 projections. MEER-CBCT achieved similar contrast enhancement as FBP method but significantly higher CNR. At 2.5% iodine solution concentration, FBP method achieved 170 HU enhancement and CNR of 2.0, considered the standard CNR for successful tumor visualization. MEER-CBCT achieved the same CNR but at ~6.3 times lower iodine concentration of 0.4%.

Contrast-enhanced ultrasound in pediatric blunt abdominal trauma: a systematic review.

Intra-abdominal injury is a major cause of morbidity in children. Computed tomography (CT) is the reference standard for the evaluation of hemodynamically stable abdominal trauma. CT has an increased risk of long-term radiation induced malignancies and a possible risk associated with the use of iodinated contrast media. Contrast-enhanced ultrasound (CEUS) might represent an alternative to CT in stable children with blunt abdominal trauma (BAT). Nonetheless, CEUS in pediatrics remains limited by the lack of strong evidence. The purpose of this study was to offer a systematic review on the use of CEUS in pediatric abdominal trauma. Electronic search of PubMed, EMBASE and Cochrane databases of studies investigating CEUS for abdominal trauma in children. The risk of bias was assessed using the ROBINS-I tool. This systematic review included 7 studies. CEUS was performed with different ultrasound equipment, always with a curvilinear transducer. Six out of seven studies used a second-generation contrast agent. No immediate adverse reactions were reported. The dose of contrast agent and the scanning technique varied between studies. All CEUS exams were performed by radiologists, in the radiology department or at the bedside. No standard training was reported to become competent in CEUS. The range of sensitivity and specificity of CEUS were 85.7 to 100% and 89 to 100%, respectively. CEUS appears to be safe and accurate to identify abdominal solid organ injuries in children with BAT. Further research is necessary to assess the feasibility of CEUS by non-radiologists, the necessary training, and the benefit-cost ratio of CEUS as a tool to potentially reduce CT scans.

Comparison of low-dose contrast computed tomography angiography findings with surgical results in living kidney donors

Aim: To analyze the image quality and diagnostic performance of CT angiography using low dose (60 ml) contrast medium for living kidney donors and compare with surgical results.&#x0D; Material and Method: Angiographic findings of 81 renal donor candidates in 128-slice MDCT were evaluated by two independent radiologists in terms of renal artery number, early bifurcation, renal vein variations, pelvicalyceal system and ureter variations. Results were compared with intraoperative findings. The image quality, diagnostic performance and interobserver agreement of MDCT obtained with low dose contrast material were analyzed.&#x0D; Results: The mean age of the 81 living kidney donors included in the study was 49±12 (24-68) years. Left nephrectomy was performed in 71% (n=64) and right nephrectomy in 29% (n=17) of the donors. Intraoperative accessory arteries were detected in 22.2% (n:18) of the donors. The specificity, sensitivity, and accuracy for detecting accessory artery variation in MDCT were 100%, 88.9%, and 97.5%, respectively. Early bifurcation was observed in 21% (n=17) of the donors. Specificity, sensitivity and accuracy for early bifurcation detection were 98.4%, 94.1% and 97.5%, respectively. Renal vein variation was detected in 12.3% (n=10) of the donors. Specificity, sensitivity, and accuracy for renal vein variation detection were 100%. Variations of the pelvicalyceal system and ureter were observed in 3.7% (n=3) of the donors. The specificity, sensitivity, and accuracy for detecting pelvicalyceal system and ureteral variations were 100%. Interobserver agreement was excellent in detecting variations of accessory arteries, renal venous anomalies, pelvicalyceal system and ureters by MDCT (kappa: 1,000; p&lt; 0.001). It was higher in early bifurcation detection (kappa: 0.853; p&lt; 0.001).&#x0D; Conclusion: MDCT angiography with a lower dose of iodine contrast at 60 mL in kidney donors is sufficient to detect vascular anomalies and provide anatomical information. It is possible to reduce the contrast agent dose in CTA without affecting the preoperative evaluation.

Right adrenal vein identification using unenhanced magnetic resonance imaging.

Unenhanced magnetic resonance imaging (MRI) is known to be useful in characterizing adrenal adenomas through the implementation of in-phase (IPI) and opposed-phase imaging (OPI) based on chemical shift artifacts. However, whether unenhanced MRI can contribute to the identification of right adrenal vein (RAV) remains unclear. The aim of this study was to evaluate the feasibility of unenhanced MRI for the identification of RAV. This retrospective study reviewed 30 patients (16 men; median age 60 years; range 34-76 years) who underwent MRI and subsequent adrenal venous sampling (AVS). Chemical shift MRI was acquired using echo times of 2.3 ms (OPI) and 4.6 ms (IPI) with a slice thickness of 3 mm and a gap of 1 mm. T2-weighted imaging (T2WI) was also performed. Identification of RAVs was performed by 2 independent radiologists. Inter-observer agreement on a 3-point rating scale was evaluated using κ statistics. The identification rate of RAVs was compared between OPI, IPI, and T2WI using McNemar's test. Good inter-observer agreement was found for the OPI (κ = 0.744), whereas fair agreement was obtained for both other sequences (IPI: κ = 0.375; T2WI: 0.348). For both raters, the identification rate of RAVs was higher with OPI (36/60; 60.0%) than with other sequences (IPI: 16/60, 26.7%; T2WI: 9/60, 15.0%; p < 0.05, each). OPI may play a screening role in the identification of RAVs preceding AVS, which could reduce the required radiation exposure and doses of contrast agent.