Evaluation of a Tube Voltage-Based Contrast Media Adaptation in Coronary Computed Tomography Angiography Using Personalized Triphasic Injection Protocols: A Matched Case-Control Study.

RATIONALE AND OBJECTIVES: Coronary CT angiography (CCTA) has recently been established as a first-line test in patients with suspected coronary artery disease (CAD). Due to the increased use of CCTA, strategies to reduce radiation and contrast medium (CM) exposure are of high importance. The aim of this study was to evaluate the performance of automated tube voltage selection (ATVS)-adapted CM injection protocol for CCTA compared to a clinically established triphasic injection protocol in terms of image quality, radiation exposure, and CM administration MATERIAL AND METHODS: Patients undergoing clinically indicated CCTA were prospectively enrolled from July 2021 to July 2023. Patients underwent CCTA using a modified triphasic CM injection protocol tailored to the tube voltage by the ATVS algorithm, in a range of 70 to 130 kV with a 10 kV interval. The injection protocol consisted of two phases of mixed CM and saline boluses with different proportions to assure a voltage-specific iodine delivery rate, followed by a third phase of saline flush. This cohort was compared to a control group identified retrospectively and scanned on the same CT system but with a standard triphasic CM protocol. Radiation and contrast dose, subjective and objective image quality (contrast-to-noise-ratio [CNR] and signal-to-noise-ratio [SNR]) were compared between the two groups. RESULTS: The final population consisted of 120 prospective patients matched with 120 retrospective controls, with 20 patients in each kV group. The 120 kV group was excluded from the statistical analysis due to insufficient sample size. A significant CM reduction was achieved in the prospective group overall (46.0 [IQR 37.0-52.0] vs. 51.3 [IQR 40.1-73.0] mL, p < 0.001) and at all kV levels too (all pairwise p < 0.001). There were no significant differences in radiation dose (6.13 ± 4.88 vs. 5.97 ± 5.51 mSv, p = 0.81), subjective image quality (median score of 4 [3-5] vs. 4 [3-5], p = 0.40), CNR, and SNR in the aorta and the left anterior descending coronary artery (all p > 0.05). CONCLUSION: ATVS-adapted CM injection protocol allows for diagnostic quality CCTA with reduced CM volume while maintaining similar radiation exposure, subjective and objective image quality.

Iopromide for Contrast-Enhanced Mammography: A Systemic Review and Meta-Analysis of Pertinent Literature.

Background: Contrast-enhanced mammography (CEM) is an emerging breast imaging modality. Clinical data is scarce. Objectives: To summarize clinical evidence on the use of iopromide in CEM for the detection or by systematically analyzing the available literature on efficacy and safety. Design: Systematic review and meta-analysis. Data sources and methods: Iopromide-specific publications reporting its use in CEM were identified by a systematic search within Bayer's Product Literature Information (PLI) database and by levering a recent review publication. The literature search in PLI was performed up to January 2023. The confirmatory-supporting review publication was based on a MEDLINE/EMBASE + full text search for publications issued between September 2003 and January 2019. Relevant literature was selected based on pre-defined criteria by 2 reviewers. The comparison of CEM vs traditional mammography (XRM) was performed on published results of sensitivity and specificity. Differences in diagnostic parameters were assessed within a meta-analysis. Results: Literature search: A total of 31 studies were identified reporting data on 5194 patients. Thereof, 19 studies on efficacy and 3 studies on safety. Efficacy: in 11 studies comparing iopromide CEM vs XRM, sensitivity was up to 43% higher (range 1%-43%) for CEM. Differences in specificity were found to be in a range of -4% to 46% for CEM compared with XRM. The overall gain in sensitivity for CEM vs XRM was 7% (95% CI [4%, 11%]) with no statistically significant loss in specificity in any study assessed. In most studies, accuracy, positive predictive value, and negative predictive value were found to be in favor of CEM. In 2 studies comparing CEM with breast magnetic resonance imaging (bMRI), both imaging modalities performed either equally well or CEM tended to show better results with respect to sensitivity and specificity. Safety: eight cases of iopromide-related adverse drug reactions were reported in 1022 patients (0.8%). Conclusions: Pertinent literature provides evidence for clinical utility of iopromide in CEM for the detection or confirmation of breast cancer. The overall gain in sensitivity for iopromide CEM vs XRM was 7% with no statistically significant loss in specificity.

Developments in X-Ray Contrast Media and the Potential Impact on Computed Tomography.

Over the past 120 years, continuous developments in medical imaging has improved diagnosis and treatment for many diseases and has thereby improved treatment outcome and quality of life of many patients. The number of computed tomography (CT) examinations is today increasing by 4% per year worldwide, for a total of approximately 300 million CT scans per year. About 40% of CT scans are contrast enhanced. Intravenous iodinated contrast media are commonly used for contrast enhancement in CT scans to evaluate diseases and determine treatment response. The current gold standards for intravenous x-ray contrast media in CT or interventional angiography are iodinated low- and iso-osmolar compounds such as iopromide, iohexol, or iodixanol. Both classes have similar and favorable efficacy and safety profiles. Although iodine is biologically inert, iodinated contrast media can cause adverse reactions. In the future, one possibility would be to develop iodine-free contrast media that are better suited to higher x-ray tube voltage ranges, allowing greater flexibility for scanning protocols and thus leading to techniques that can provide equivalent diagnostic value at lower doses of radiation. Iodine-free contrast media would in addition provide an alternative to the market standard that could offer benefits for patients with known reactions to low-osmolality contrast media or thyroid disorders. The development of a new contrast medium, however, needs to be put in context with all upcoming technological advances in x-ray and CT. New detector technologies and artificial intelligence algorithms will in the future also improve the CT image reconstruction enabling the reduction of contrast media and radiation doses.

Contrast timing in computed tomography: effect of different contrast media concentrations on bolus geometry.

OBJECTIVE: To assess the effect of low-osmolar, monomeric contrast media with different iodine concentrations on bolus shape in aortic CT angiography. MATERIALS AND METHODS: Repeated sequential computed tomography scanning of the descending aorta of eight beagle dogs (5 male, 12.7±3.1kg) was performed without table movement with a standardized CT scan protocol. Iopromide 300 (300mgI/mL), iopromide 370 (370mgI/mL) and iomeprol 400 (400mgI/mL) were administered via a foreleg vein with an identical iodine delivery rate of 1.2gI/s and a total iodine dose of 300mgI/kg body weight. Time-enhancement curves were computed and analyzed. RESULTS: Iopromide 300 showed the highest peak enhancement (445.2±89.1 HU), steepest up-slope (104.2±17.5 HU/s) and smallest full width at half maximum (FWHM; 5.8±1.0s). Peak enhancement, duration of FWHM, enhancement at FWHM and up-slope differed significantly between iopromide 300 and iomeprol 400 (p<0.05). Except for enhancement at FWHM there were no significant differences between iopromide 300 and iopromide 370 and iopromide 370 and iomeprol 400 (p>0.05). CONCLUSIONS: Low viscous iopromide 300 results in a better defined bolus with a significantly higher peak enhancement, steeper up-slope and smaller FWHM when compared to iomeprol 400. These characteristics potentially affect contrast timing.

Perfusion-weighted map and perfused blood volume in comparison with CT angiography source imaging in acute ischemic stroke different sides of the same coin?

RATIONALE AND OBJECTIVES: Computed tomography angiography source imaging (CTA-SI) in acute ischemic stroke improves detection rate and estimation of extent of cerebral infarction. This study compared the new components color-coded perfusion weighted map (PWM) and color-coded perfused blood volume (PBV) derived from CTA data with CTA-SI for the visualization of cerebral infarction. MATERIALS AND METHODS: Fifty patients (women = 30; mean age = 74.9 ± 13.3 years) underwent nonenhanced computed tomography and CTA for suspected acute ischemic stroke. PWM, PBV, and CTA-SI were reconstructed with identical slice thickness of 1.0 mm with commercial software. Extent of infarction was measured using the Alberta Stroke Program Early Computed Tomography Score (ASPECTS). For statistical analysis, Spearman's R correlation and paired-samples t-test was used. P < .05 was considered significant. RESULTS: PBV had superior sensitivity for detection of cerebral infarction with 0.88 compared to PWM and CTA-SI with 0.79 and 0.76, respectively. The accuracy of correct diagnosis was superior for PBV with 0.82 compared to PWM and CTA-SI with 0.76, respectively. ASPECTS of PWM and PBV showed strong correlation with CTA-SI with r = 0.903 (P < .001) and r = 0.866 (P < .001), respectively. Mean ASPECTS of CTA-SI (6.24 ± 3.62) revealed no significant difference with PWM (6.26 ± 3.45), but a significant difference with PBV (5.62 ± 3.41; P < .02). CONCLUSIONS: PWM was equal to CTA-SI in detection of cerebral infarction and estimation of extent of cerebral ischemia. Although PBV was superior to CTA-SI in detection of cerebral infarction, PBV seems to overestimate the extent of critical cerebral ischemia. Therefore, CTA-SI information is not identical to PBV and further clinical evaluation is mandatory.

Prospective study of access site complications of automated contrast injection with peripheral venous access in MDCT.

OBJECTIVE: The purpose of this article is to prospectively assess the frequency and type of IV injection site complications associated with high-flow power injection of nonionic contrast medium in MDCT. SUBJECTS AND METHODS: Contrast-enhanced (300-370 mg iodine/mL) MDCT examinations with high flow rates (up to 8 mL/s) using automatic CT injectors were performed according to standardized MDCT protocols. The location, type, and size (16-24 gauge) of IV catheters and volumes, iodine concentration, and flow rates of contrast medium were documented. Patients were questioned about associated discomfort, IV catheter sites were checked, and adverse effects were recorded. RESULTS: Prospectively, 4,457 patients were studied. The injection rate ranged from 1-2.9 mL/s (group 1; n = 1,140) to 3-4.9 mL/s (group 2; n = 2,536) to 5-8 mL/s (group 3; n = 781); 1.2% of the patients experienced extravasations (n = 52). Contrast medium iodine concentration, flow rates, and volumes were not related to the frequency of extravasation. The extravasation rate was highest with 22-gauge IV catheters (2.2%; p < 0.05) independently of the anatomic location. For 20-gauge IV catheters, extravasation rates were significantly higher in the dorsum of the hand than in the antecubital fossa (1.8% vs 0.8%; p = 0.018). Extravasation rates were higher in older patients (≥ 50 vs < 50 years, 0.6% vs 1.4%; p = 0.019). Different iodine concentrations did not trigger significant differences in contrast material reactions (p = 0.782). CONCLUSION: Automated IV contrast injection applying high flow rates (i.e., up to 8 mL/s) is performed without increased risk of extravasation. The overall extravasation rate was 1.2% and showed no correlation with iodine concentration, flow rates, or contrast material reactions. Performing high flow rates with low-diameter IV catheters (e.g., 22-gauge catheters) and a location of IV catheter in the hand is associated with a higher extravasation rate.

Biphasic contrast medium injection in cardiac CT: moderate versus high concentration contrast material at identical iodine flux and iodine dose.

OBJECTIVE: To prospectively investigate the influence of contrast material concentration on enhancement in cardiac CT by using a biphasic single-injection protocol. METHODS: Sixty-four-row multidetector cardiac CT angiography was performed in 159 patients randomised to a moderate or high contrast medium concentration. Contrast material injection included a first phase for enhancement of the coronary arteries and a second phase, at half the iodine flux, targeted at enhancement of the right ventricle. Contrast medium injection was followed by a saline flush. For both concentrations, injection duration (and thus total iodine dose) was adapted to the duration of the CT data acquisition and iodine flux was adjusted to patient weight. Attenuation was measured at various levels in the heart and vessels and the two concentrations compared, overall and per weight group. RESULTS: Enhancement of the aorta and left ventricle was significantly greater with the moderate than with the high concentration contrast medium. This remained true for the two higher weight groups. No difference was found in the lowest weight group or in the right ventricle and pulmonary outflow tract. CONCLUSION: With a biphasic injection protocol, enhancement of the aorta and left ventricle was weaker with the higher concentration of contrast material.

Intra-individual comparison of different contrast media concentrations (300 mg, 370 mg and 400 mg iodine) in MDCT.

OBJECTIVE: To compare intra-individual contrast enhancement in multi-detector-row computed tomography (MDCT) using contrast media (CM) containing 300, 370 and 400 mg iodine per ml (mgI/ml). METHODS: Six pigs underwent repeated chest MDCT using three different CM (iopromide 300, iopromide 370, iomeprol 400). An identical iodine delivery (IDR) rate of 1.5 gI/s and a constant total iodine dose of 300 mg/kg body weight were used. Dynamic CT were acquired at the level of the pulmonary artery, and the ascending and descending aorta. After the time enhancement curves were computed, the pulmonary and aortic peak enhancement, time to peak and plateau time above 300 HU were calculated. RESULTS: Intra-individual peak contrast enhancement was significantly higher for the 300 mgI/ml contrast medium compared with the 370 and 400 mgI/ml media: pulmonary trunk 595 HU vs 516 HU (p = 0.0093) vs 472 HU (p = 0.0005), and aorta 505 HU vs 454 HU (p = 0.0008) vs 439 HU (p = 0.0001), respectively. Comparison of time to peaks showed no significant difference. Plateau times were significantly longer for the 300 mgI/ml than for the 370 and 400 mgI/ml CM at all anatomical sites. CONCLUSION: Given normalised IDR and total iodine burden, the use of CM with a standard concentration with 300 mg iodine/ml provides improved contrast enhancement compared with highly concentrated CM in the chest.

Whole brain perfused blood volume CT: visualization of infarcted tissue compared to quantitative perfusion CT.

RATIONALE AND OBJECTIVES: This study determines the value of whole brain color-coded three-dimensional perfused blood volume (PBV) computed tomography (CT) for the visualization of the infarcted tissue in acute stroke patients. MATERIALS AND METHODS: Nonenhanced CT (NECT), perfusion CT (PCT), and CT angiography (CTA) in 48 patients with acute ischemic stroke were performed. Whole brain PBV was calculated from NECT and CTA data sets using commercial software. PBV slices in identical orientation to the PCT slices were reconstructed and the area of visual perfusion abnormality on PBV maps was measured. The infarct core in the corresponding PCT slices (CBV <2.0 mL/100 g) was measured automatically with commercial software. The ischemic area on PBV and the infarct core on quantitative PCT were compared using the Pearsons-R correlation coefficient. Significance was considered for P < .05. RESULTS: The quantitative PCT demonstrated a mean infarct core volume of 35.48 +/- 32.17 cm(3), whereas the volume of visual perfusion abnormality of the corresponding PBV slices was 37.16 +/- 37.59 cm(3). The perfusion abnormality in PBV was highly correlated with the infarct core of quantitative PCT for area per slice (r = 0.933, P < .01) as well as volume (r = 0.922, P < .01). CONCLUSIONS: PBV can serve as surrogate marker corresponding to the infarct core in acute stroke with whole brain coverage.

Dual energy CTA of the supraaortic arteries: technical improvements with a novel dual source CT system.

OBJECTIVES: Computed tomography angiography (CTA) is a well-accepted imaging modality to evaluate the supraaortic vessels. Initial reports have suggested that dual energy CTA (DE-CTA) can enhance diagnosis by creating bone-free data sets, which can be visualized in 3D, but a number of limitations of this technique have also been addressed. We sought to describe the performance of DE-CTA of the supraaortic vessels with a novel dual source CT system with special emphasis on image quality and post-processing related artifacts. MATERIALS AND METHODS: Thirty-three patients underwent carotid CT angiography on a second generation dual source CT system. Simultaneous acquisitions of 100 and 140kV data sets in arterial phase were performed. Two examiners evaluated overall bone suppression with a 3-point scale (1=poor; 3=excellent) and image quality regarding integrity of the vessel lumen of different vessel segments (n=26) with a 5-point scale (1=poor; 5=excellent), CTA source data served as the reference. RESULTS: Excellent bone suppression could be achieved in the head and neck. Only minor bone remnants occurred, mean score for bone removal was 2.9. Mean score for vessel integrity was 4.3. Eight hundred fifty-seven vessel segments could be evaluated. Six hundred thirty-five segments (74%) showed no lumen alteration, 65 segments (7.6%) lumen alterations <10%, 27 segments (3.1%) lumen alterations >10% resulting in a total luminal reduction <50%, 17 segments (2%) lumen alterations of more than 10% resulting in a total luminal reduction >50%, and 113 segments (13.2%) showed a gap in the vessel course (100% total lumen reduction). Artificial gaps of the vessel lumen occurred in 28 vessel segments due to artifacts caused by dental hardware and in all but one (65) ophthalmic arteries. CONCLUSIONS: Excellent bone suppression could be achieved, DE imaging with 100 and 140kV lead to improved image quality and vessel integrity in the shoulder region than previously reported. The ophthalmic artery still cannot be adequately visualized.

Ultra-fast carotid CT-angiography: low versus standard volume contrast material protocol for a 128-slice CT-system.

OBJECTIVES: Noninvasive imaging is increasingly accepted for the evaluation of atherosclerotic disease of the carotid arteries. We sought to evaluate the feasibility of a low-contrast media volume protocol for carotid computed tomography angiography (CTA) using a 128-slice-spiral-computed tomography scanner with a gantry rotation time of 300 milliseconds. METHODS AND MATERIALS: Thirty consecutive patients underwent CTA for the evaluation of the carotid vessels, with a 128-section scanner. Fifteen patients were examined with a standard volume contrast injection protocol (group A): 80 mL of contrast material (CM) were injected at 5 mL/s using the test bolus method to assess individual transit time. Another 15 patients were examined with a low-volume contrast media protocol (group B): 30 mL CM were injected at 4 mL/s using bolus tracking to trigger the CTA acquisition. In both groups, contrast administration was followed by a saline flush. Image quality and segmental vascular enhancement as well as the presence and degree of arterial stenosis were independently evaluated by 2 radiologists. Venous enhancement and streak artifacts at the thoracic inlet because of highly concentrated CM in the subclavian veins were evaluated in both groups. Kappa statistic and Pearson correlation coefficient were used to quantify interobserver variability. Qualitative data were compared using the Wilcoxon signed rank test and student t test was used to investigate differences in segmental vessel attenuation. RESULTS: All studies were of diagnostic quality in both groups. Interobserver agreement was high (kappa = 0.82, group A; kappa = 0.78, group B). Attenuation measurement showed excellent interobserver correlation in both groups (r > 0.9). Mean enhancement values were slightly higher in group A, but without statistical significance when averaged for all segments (P = 0.06). Streak artifacts impaired evaluation of 13 adjacent arterial segments in 8 patients at the level of the thoracic inlet in group A. In group B, only 1 segment was rated insufficient by both radiologists. Venous enhancement was significantly lower in group B (P = 0.04). The low-contrast protocol proved to be the more robust method with constant high arterial enhancement, less streak artifacts at the thoracic inlet, and less venous overlay. CONCLUSION: Using the latest CT technology, optimal depiction of the craniocervical arteries can be archived with a low-volume (30 mL) CM protocol.

Contrast enhancement in chest multidetector computed tomography: intraindividual comparison of 300 mg/ml versus 400 mg/ml iodinated contrast medium.

RATIONALE AND OBJECTIVES: We sought to intraindividually compare intravascular contrast enhancement in multidector computed tomography (MDCT) of the chest using contrast media (CM) containing 300 and 400 mg iodine/ml. MATERIALS AND METHODS: Seventy-one patients underwent repeated MDCT scanning of the chest at baseline and follow-up. CM with standard iodine (protocol A: 300 mg iodine/ml; Iopromide 300) and high iodine concentration (protocol B: 400 mg iodine/ml; Iomeprol 400) were used. The iodine delivery rate (1.29 g iodine/s) and total iodine load (37 g iodine) were identical for the two protocols. Contrast enhancement was measured in the right and left ventricles, pulmonary trunk, right and left pulmonary arteries, and ascending and descending aortas. Results were compared using paired t-tests; P values were adjusted using Bonferroni correction (P .005). In the right ventricle, pulmonary trunk, and right and left pulmonary arteries, higher attenuation values for protocol A were detected compared to protocol B (379.0 +/- 110.5 vs. 349.8 +/- 117.6, 354.5 +/- 112.2 vs 330.9 +/- 118.3, 348.6 +/- 106.0 vs. 321.8 +/- 109.9, and 347.9 +/- 102.4 vs. 321.0 +/- 104.9 HU, respectively). After the lung circulation (left ventricle, ascending aorta, and descending aorta), attenuation values were marginally higher for protocol B. Using both protocols resulted in suitable contrast enhancement with a mean pulmonary attenuation higher than 300 HU. CONCLUSIONS: Using an adapted injection protocol, the administration of 300 and 400 mg iodine CM resulted in a suitable intravascular contrast enhancement in the chest. The use of 400 mg iodine CM does not lead to a statistically significant improvement in contrast enhancement compared to the 300 mg iodine CM.

Multidetector computed tomography (MDCT) evaluation of myocardial viability: intraindividual comparison of monomeric vs. dimeric contrast media in a rabbit model.

To evaluate the influence of different types of iodinated contrast media on the assessment of myocardial viability, acute myocardial infarction (MI) was surgically induced in six rabbits. Over a period of 45 min, contrast-enhanced cardiac MDCT (64 x 0.6 mm, 80 kV, 680 mAs(eff.)) was repeatedly performed using a contrast medium dose of 600 mg iodine/kg body weight. Animals received randomized iopromide 300 and iodixanol 320, respectively. Attenuation values of healthy and infarcted myocardium were measured. The size of MI was computed and compared with nitroblue tetrazolium (NBT)-stained specimen. The highest attenuation differences between infarcted and healthy myocardium occurred during the arterial phase with 140.0+/-3.5 HU and 141.0+/-2.2 HU for iopromide and iodixanol, respectively. For iodixanol the highest attenuation difference on delayed contrast-enhanced images was achieved 3 min post injection (73.5 HU). A slightly higher attenuation difference was observed for iopromide 6 min after contrast medium injection (82.2 HU), although not statistically significant (p=0.6437). Mean infarct volume as measured by NBT staining was 33.5%+/-13.6%. There was an excellent agreement of infarct sizes among NBT-, iopromide- and iodixanol-enhanced MDCT with concordance-correlation coefficients ranging from rho(c)=0.9928-0.9982. Iopromide and iodixanol both allow a reliable assessment of MI with delayed contrast-enhanced MDCT.

Retention of iodine and expression of biomarkers for renal damage in the kidney after application of iodinated contrast media in rats.

OBJECTIVE: Commercially available iodinated contrast media (CM) show significantly different physico-chemical properties. The relevance of the viscosity of CM may be underestimated as a contributing factor for clinically relevant renal failure as suggested by a large registry data analysis (Swedish registry study). The objective of this preclinical study is to assess differences of a low and high-viscous CM regarding their retention time in the kidney. Furthermore, we investigated the expression of marker genes for renal damage and hypoxia to evaluate a potential renal damage and hypoxia after application of iodinated CM. MATERIAL AND METHODS: After application of Iopromide 300 and Iodixanol 320 CM, the iodine concentration over time was determined using computed tomography and x-ray fluorescence analysis in healthy Han Wistar and renally impaired ZSF1 rats. The latter served as a model for age and diabetes-related renal impairment. X-ray attenuation (Hounsfield units) in the renal cortex was analyzed by 2 independent blinded readers. Furthermore, the expression of kidney injury molecule 1 (Kim-1/Havcr1) and heme oxygenase I (HO-1/HMOX1) was measured by quantitative reverse transcription-polymerase chain-reaction. RESULTS: Computed tomography and x-ray fluorescence analysis in the kidneys of animals treated with Iodixanol revealed significantly prolonged retention of iodine in the kidney as compared with animals treated with Iopromide. This difference was even more pronounced in renally impaired rats. Twenty-four hours after Iodixanol treatment, significantly increased levels of Kim-1/Havcr1 and HO-1/HMOX1 transcript levels were observed compared with the saline and Iopromide treatment. CONCLUSIONS: A prolonged retention of contrast media in the kidney was observed after administration of dimeric CM (Iodixanol 320). One possible explanation for this effect could be the high viscosity of the dimeric CM (Iodixanol 320) and the lack of dilution by osmotic diuresis. This prolonged exposure is possibly associated with higher renal toxicity as indicated by the elevated expression of biomarkers for hypoxia and renal injury.

Assessment of the tolerance dose of the hepatic reticulo-endothelial system (RES) after single fraction HDR-irradiation: an in-vivo study employing SSPIO.

PURPOSE: To prospectively assess a dose-response relationship for the hepatic reticulo-endothelial system (RES) after small volume single fraction irradiation of liver parenchyma in vivo. MATERIALS AND METHODS: Twenty-five liver tumors were treated by computed tomography (CT)-guided interstitial brachytherapy. Magnetic resonance imaging (MRI) was performed 1 day before and 3 days, 6, 12 and 24 weeks after therapy. MR-sequences included T2-w Turbo Spin Echo (TSE) enhanced by hepatic RES targeted Standard Superparamagnetic Iron Oxide (SSPIO). All MRI data sets were merged with three dimensional (3D) dosimetry data and evaluated by two radiologists. We estimated the threshold dose for either edema or function loss as the D90. A match-pair analysis was performed with another 25 liver tumors, which were treated the same but had MRI follow-up using the hepatocyte specific MRI contrast media Gadobenate dimeglumine (Gd-BOPTA). RESULTS: Three days post brachytherapy the D90 for hepatic RES function loss reached the 18.3 Gray (Gy) isosurface (Standard Deviation (SD) 7.7). At 6 weeks, the respective zone had increased significantly to the 12.9 Gy isosurface (SD 4.4). After 12 and 24 weeks, the dysfunction of liver volume decreased significantly to the 15 Gy and 20.4 Gy isosurface respectively (SD 7.1 and 10.0). Comparison to the hepatocyte function loss indicates a higher minimal threshold dose of the hepatic RES. CONCLUSION: Hepatic RES demonstrated a high regenerative capacity and a higher minimal threshold dose than hepatocytes. Temporary function loss was found from the 13 Gy isosurface.

Which Iodine concentration in chest CT?--a prospective study in 300 patients.

In computed tomography (CT) several contrast media with different iodine concentrations are available. The aim of this study is to prospectively compare contrast media with iodine concentrations of 300, 370 and 400 mg iodine/ml for chest- CT. 300 consecutive patients were prospectively enrolled, under a waiver of the local ethics committee. The first (second, third) 100 patients, received contrast medium with 300 (370, 400) mg iodine/ml. Injection protocols were adapted for an identical iodine delivery rate (1.3 mg/s) and total iodine load (33 g) for all three groups. Standardized MDCT of the chest (16 x 0.75 mm, 120 kVp, 100 mAseff.) was performed. Intravascular attenuation values were measured in the pulmonary trunk and the ascending aorta; subjective image quality was rated on a 3-point-scale. Discomfort during and after injection was evaluated. There were no statistically significant differences in contrast enhancement comparing the three contrast media at the pulmonary trunk (p = 0.3198) and at the ascending aorta (p = 0.0840). Image quality (p = 0.0176) and discomfort during injection (p = 0.7034) were comparable for all groups. General discomfort after injection of contrast media with 300 mg iodine/ml was statistically significant higher compared to 370 mg iodine/ml (p = 0.00019). Given identical iodine delivery rates of 1.3 g/s and iodine loads of 33 g, contrast media with concentrations of 300, 370 and 400 mg iodine/ml do not result in different intravascular enhancement in chest-CT.

Intraindividual comparison of contrast media concentrations for combined abdominal and thoracic MDCT.

OBJECTIVE: The purpose of this study was an intraindividual comparison of the degrees of MDCT contrast enhancement achieved with agents containing 300 and 370 mg I/mL. SUBJECTS AND METHODS: Seventy-five patients underwent baseline and follow-up MDCT of the chest and abdomen with contrast media containing a high concentration of iodine (iopromide 370 mg I/mL) and standard iodine concentration (iopromide 300 mg I/mL). The total iodine load (37 g) and the iodine delivery rate (1.29 g/s) were identical for the two protocols. Contrast enhancement in the chest (right and left ventricles, pulmonary trunk, descending aorta) and the abdomen (aorta, inferior vena cava, portal vein, and liver) was determined. Results were compared by use of paired Student's t tests, and p was adjusted with Bonferroni correction for multiple comparisons (p 0.0056). CONCLUSION: Given equivalent iodine load and delivery rate, the use of 300 mg I/mL contrast medium results in better contrast enhancement than use of 370 mg I/mL contrast medium in CT of the chest. For the portal venous phase of CT of the abdomen, there was no significant difference in contrast enhancement for the two concentrations of iodine.

Comparison between a linear versus a macrocyclic contrast agent for whole body MR angiography in a clinical routine setting.

BACKGROUND: Previous experiences of whole body MR angiography are predominantly available in linear 0.5 M gadolinium-containing contrast agents. The aim of this study was to compare image quality on a four-point scale (range 1-4) and diagnostic accuracy of a 1.0 M macrocyclic contrast agent (gadobutrol, n = 80 patients) with a 0.5 M linear contrast agent (gadopentetate dimeglumine, n = 85 patients) on a 1.5 T whole body MR system. Digital subtraction angiography served as standard of reference. RESULTS: All examinations yielded diagnostic image quality. There was no significant difference in image quality (3.76 +/- 0.3 versus 3.78 +/- 0.3, p = n.s.) and diagnostic accuracy observed. Sensitivity and specificity of the detection of hemodynamically relevant stenoses was 93%/95% in the gadopentetate dimeglumine group and 94%/94% in the gadobutrol group, respectively. CONCLUSION: The high diagnostic accuracy of gadobutrol in the clinical routine setting is of high interest as medical authorities (e.g. the European Agency for the Evaluation of Medicinal Products) recommend macrocyclic contrast agents especially to be used in patients with renal failure or dialysis.

Comparison of different iodine concentration contrast media in perfusion computed tomography of the brain: is high iodine concentration useful?

OBJECTIVES: To investigate maximum enhancement and visual map quality in cerebral perfusion computed tomography (PCT) with variation of iodine concentration of contrast media (CM). MATERIALS AND METHODS: Two groups of 45 patients each, underwent PCT with either 370 mg iodine/mL (30 mL; 6 mL/s) or 300 mg iodine/mL (40 mL; 8 mL/s) CM, respectively, and similar total iodine dose. Parenchymal and vascular enhancement as well as contrast-to-noise ratio of superior sagittal sinus was measured on PCT source images. PCT maps were rated visually with dichotomized scale for diagnostic quality. RESULTS: Enhancement and contrast-to-noise ratio of the superior sagittal sinus was significantly higher for the 370 mg iodine/mL protocol (P < 0.0002 and P < 0.007), whereas parenchymal enhancement was not significantly different. Diagnostic quality of PCT maps did not differ between both protocols (P < 0.557). CONCLUSIONS: PCT using 370 mg iodine/mL CM can be reliably performed with reduced injection rate and less total volume enabling smaller diameter of intravenous canula compared with 300 mg iodine/mL CM.