Iodinated contrast media and cerebral hemorrhage after intravenous thrombolysis

<p>Background and Purpose: Iodinated contrast is increasingly used in CT perfusion or angiographic examinations in acute stroke. Increased risk of intracranial hemorrhage (ICH) complicating microcatheter contrast injections has recently been reported in the second Interventional Management of Stroke (IMS 2) trial with contrast toxicity potentially contributory.</p> <p>Methods: We reviewed clinical and radiological data on all patients treated with intravenous alteplase at a single center between May 2003 and November 2008.</p> <p>Results: Of 312 patients treated with intravenous alteplase, 69 (22.1%) received intravenous iodinated contrast in volumes between 50 and 150 mL. Incidence of symptomatic ICH defined as per European Cooperative Acute Stroke Study 2 was 16 of 312 (5.1%; 95% CI, 2.7% to 7.6%); among patients not given contrast, it was 12 of 243 (4.9%; 2.2% to 7.7%) compared with 4 of 69 (5.8%; 0.3% to 11.3%) in those given contrast. Incidence of symptomatic ICH defined as per Safe Implementation of Thrombolysis in Stroke-MOnitoring Study (SITS-MOST) criteria was 12 of 312 (3.9%; 1.7% to 6%), 9 of 243 (3.7%; 1.3% to 6%) among those not given contrast, and 3 of 69 (4.4%; 95% CI, -0.5% to 9.2%) among those given contrast. Patients with symptomatic ICH were older, had higher pretreatment National Institutes of Health Stroke Scale, and blood glucose than those without symptomatic ICH. In logistic regression analysis, pretreatment blood glucose was the only significant predictor of symptomatic ICH by either definition (OR, 1.23; 95% CI, 1.03 to 1.48 per mmol/L increment; P=0.024). Contrast administration or dose was not associated with symptomatic ICH.</p> <p>Conclusions: Intravenous iodinated contrast in doses typically required for CT angiography and perfusion imaging was not associated with symptomatic intracranial hemorrhage in patients treated with alteplase.</p&gt

Bloch Waves in Crystals and Periodic High Contrast Media

Analytic representation formulas and power series are developed describing the band structure inside periodic photonic and acoustic crystals made from high contrast inclusions. Central to this approach is the identification and utilization of a resonance spectrum for quasi-periodic source free modes. These modes are used to represent solution operators associated with electromagnetic and acoustic waves inside periodic high contrast media. Convergent power series for the Bloch wave spectrum is recovered from the representation formulas. Explicit conditions on the contrast are found that provide lower bounds on the convergence radius. These conditions are sufficient for the separation of spectral branches of the dispersion relation

Rôle of contrast media viscosity in altering vessel wall shear stress and relation to the risk of contrast extravasations

Iodinated contrast media (CM) are the most commonly used injectables in radiology today. A range of different media are commercially available, combining various physical and chemical characteristics (ionic state, osmolality, viscosity) and thus exhibiting distinct in vivo behaviour and safety profiles. In this paper, numerical simulations of blood flow with contrast media were conducted to investigate the effects of contrast viscosity on generated vessel wall shear stress and vessel wall pressure to elucidate any possible relation to extravasations. Five different types of contrast for Iodine fluxes ranging at 1.5–2.2 gI/s were modelled through 18 G and 20 G cannulae placed in an ideal vein at two different orientation angles. Results demonstrate that the least viscous contrast media generate the least maximum wall shear stress as well as the lowest total pressure for the same flow rate. This supports the empirical clinical observations and hypothesis that more viscous contrast media are responsible for a higher percentage of contrast extravasations. In addition, results support the clinical hypothesis that a catheter tip directed obliquely to the vein wall always produces the highest maximum wall shear stress and total pressure due to impingement of the contrast jet on the vessel wall

Arteriography during ex vivo renal perfusion A complication

A case of bilateral renal-cell carcinoma unsuccessfully treated with bench surgery is reported. The reason for failure was apparently the toxicity of the contrast media used during the ex vivo arteriographic studies. © 1973

Intravenous contrast media optimization at computed tomography

The administration of intravenous contrast media (IV CM) is essential for detecting lesions at most computed tomography (CT) examinations. The overall aim of this thesis is to investigate different aspects of IV CM administration that may affect the quality of the CT examination. In Study I a comparison was made between a low-osmolar contrast media (LOCM) iomeprol and the iso-osmolar contrast medium (IOCM) iodixanol, focusing on how they affect heart rate (HR), influence patient heat sensation and image quality during coronary computed angiography (CCTA). No significant difference in terms of HR interfering with the imaging protocol was observed. However, there was a larger number of arrhythmic heart beats (HB) observed when using LOCM in comparison to IOCM (p < 0.001). There was no statistically significant difference in image quality between the two CM. The experienced heat sensation was significantly stronger with LOCM in comparison to IOCM (visual analogue scale = 36 mm and 18 mm respectively, p< 0.05). In Study II the variation in IV CM-enhancement in Hounsfield units (HU) in the liver and the aorta in relation to different expressions of body size was studied using two different CM (LOCM iomeprol and IOCM iodixanol). A significant relationship was observed for all studied body size parameters. Three parameters had a stronger correlation to the CM-enhancement; Body weight (BW, r= -0.51 and -0.64 ), body surface area (BSA, r= -0.54 and -0.65) and lean body mass (LBM, r= -0.54 and -0.59), but there was no statistically significant difference between those. Body height (BH), body mass index (BMI) and ideal body weight (IBW) had weaker correlations to CM- enhancement of the liver and the aorta. When adjusting for differences in weight, height, age and sex between the two groups there was a significantly stronger liver enhancement with iodixanol than with iomeprol (mean difference 6 HU, p < 0.01). In Study III the correlation between liver CM-enhancement and volume pitch-corrected computed tomographic dose index (CTDIvol) and BW was studied. Liver enhancement was negatively correlated to both CTDIvol (r = -0.60) and BW (r = -0.64). In Study IV the relationship between arm positioning, BW and cardiac output (CO) versus CM-enhancement /timing during CCTA was studied. Patients were randomized into two groups. Group A (n=50) was positioned with arms resting on a pillow above their head and Group B (n=50) with their arms resting on the front panel of the CT. Statistically significant more patients in group A compared with group B (26 versus 14) showed a higher attenuation of the left atrium in comparison to the ascending aorta indicating too early scanning after IV CM injection (p=<0.05). In both groups BW and CO were statistically significantly related to the attenuation of ascending aorta (p<0.01). Conclusion: The iso-osmolar contrast medium iodixanol causes less arrhythmic HB and less heat sensation than the low-osmolar contrast medium iomeprol, but this does not significantly influence the quality at CCTA. The positioning of the arms affects contrast media timing at CCTA. CM-enhancement of the liver and aorta is affected by body size. Several parameters can be used to adjust CM dose, but none is statistically significantly better parameter than BW. However, CTDIvol can potentially replace BW when adjusting CM dose for body size. This would make it potentially feasible to individualize CM dosage automatically by the CT scanner

Influence of contrast media dose and osmolality on the diagnostic performance of contrast fractional flow reserve

Background—Contrast fractional flow reserve (cFFR) is a method for assessing functional significance of coronary stenoses, which is more accurate than resting indices and does not require adenosine. However, contrast media volume and osmolality may affect the degree of hyperemia and therefore diagnostic performance. Methods and Results—cFFR, instantaneous wave–free ratio, distal pressure/aortic pressure at rest, and FFR were measured in 763 patients from 12 centers. We compared the diagnostic performance of cFFR between patients receiving low or iso-osmolality contrast (n=574 versus 189) and low or high contrast volume (n=341 versus 422) using FFR≤0.80 as a reference standard. The sensitivity, specificity, and overall accuracy of cFFR for the low versus iso-osmolality groups were 73%, 93%, and 85% versus 87%, 90%, and 89%, and for the low versus high contrast volume groups were 69%, 99%, and 83% versus 82%, 93%, and 88%. By receiver operating characteristics (ROC) analysis, cFFR provided better diagnostic performance than resting indices regardless of contrast osmolality and volume (P&lt;0.001 for all groups). There was no significant difference between the area under the curve of cFFR in the low- and iso-osmolality groups (0.938 versus 0.957; P=0.40) and in the low- and high-volume groups (0.939 versus 0.949; P=0.61). Multivariable logistic regression analysis showed that neither contrast osmolality nor volume affected the overall accuracy of cFFR; however, both affected the sensitivity and specificity. Conclusions—The overall accuracy of cFFR is greater than instantaneous wave–free ratio and distal pressure/aortic pressure and not significantly affected by contrast volume and osmolality. However, contrast volume and osmolality do affect the sensitivity and specificity of cFFR