Platelet and fibrin modification by radiographic contrast media. (33/131)

The effect of the radiographic contrast agents, iopamidol and diatrizoate, on fibrin assembly and structure as well as platelet surface charge was studied. Increasing the iopamidol concentration from 0 to 4.5 mM prolongs the fibrin gelation time from 20 to 105 seconds (an anticoagulant effect) and reduces the fibrin fiber mass/length ratio from 3.2 x 10(12) to 0.5 x 10(12) Da/cm (i.e., produces very thin fibrin fibers). Ultraviolet difference spectroscopy of fibrinogen showed both a 15-nm shift in the ultraviolet difference maximum for iopamidol (suggesting binding) and a perturbation of the aromatic amino acid side chain region for fibrinogen (suggesting a conformational change in fibrinogen) as the concentration of iopamidol was increased from 0 to 9 mg/ml. Binding of iopamidol to fibrinogen was also shown by affinity chromatography using a Sepharose-fibrinogen column. Electrophoretic quasi elastic light scattering was used to show platelet interaction with iopamidol as reflected in a reduction in the platelet electrophoretic mobility from 2.0 to 0.5 (microns-cm)/(V-sec) as the concentration of iopamidol was increased from 0 to 4.5 mM. In addition, the ionic radiopaque contrast agent, Renografin, was also studied and found to inhibit fibrin monomer assembly. Although iopamidol is not shown to be thrombogenic, iopamidol does appear to reduce platelet surface charge, bind fibrinogen, and modify fibrin clot structure.  (+info)

Diagnostic accuracy of multidetector computed tomography coronary angiography in patients with dilated cardiomyopathy. (34/131)

OBJECTIVES: The purpose of this work was to assess the safety, feasibility, and diagnostic accuracy of multidetector computed tomography (MDCT) in dilated cardiomyopathy (DCM) of unknown etiology. BACKGROUND: Multidetector computed tomography is an appropriate noninvasive tool for coronary artery disease (CAD) detection, particularly in patients with low probability of the disease, such as patients with DCM of unknown origin. METHODS: We studied 61 unknown origin DCM patients (ejection fraction: 33.9 +/- 8.6%, group 1) and 139 patients with normal cardiac function with indications for coronary angiography (group 2, control population). All underwent coronary MDCT and angiography. Multidetector computed tomography images were acquired by light speed 16-slice computed tomography. The degree of stenosis was estimated in 15 coronary artery segments according to the American Heart Association model. RESULTS: In group 1, no MDCT-related complications were found, while 10 complications were associated with conventional angiography (p = 0.001). Overall feasibility of coronary artery visualization was 97.2% (863 of 888 segments). The most frequent cause of artifacts was interference from a hypertrophic cardiac venous system (10 artifacts, 40%). In group 2, overall feasibility was 96.1% (p = NS vs. group 1). In group 1, all cases with normal (44 cases) or pathological (17 cases) coronary arteries by conventional coronary angiography were correctly detected by MDCT, with, in 1 case, disparity of stenosis severity. In group 1, sensitivity, specificity, and positive and negative predictive values of MDCT for the identification of >50% stenosis were 99%, 96.2%, 81.2%, and 99.8%, respectively. In group 2, sensitivity and negative predictive values were lower than in group 1 (86.1% vs. 99% and 96.4% vs. 99.8%, respectively); specificity (96.4%) and positive predictive value (86.1%) were not significantly different versus group 1. CONCLUSIONS: Multidetector computed tomography is feasible, safe, and accurate for identification of idiopathic versus ischemic DCM, and may represent an alternative to coronary angiography.  (+info)

Cardiac Angiography in Renally Impaired Patients (CARE) study: a randomized double-blind trial of contrast-induced nephropathy in patients with chronic kidney disease. (35/131)

BACKGROUND: No direct comparisons exist of the renal tolerability of the low-osmolality contrast medium iopamidol with that of the iso-osmolality contrast medium iodixanol in high-risk patients. METHODS AND RESULTS: The present study is a multicenter, randomized, double-blind comparison of iopamidol and iodixanol in patients with chronic kidney disease (estimated glomerular filtration rate, 20 to 59 mL/min) who underwent cardiac angiography or percutaneous coronary interventions. Serum creatinine (SCr) levels and estimated glomerular filtration rate were assessed at baseline and 2 to 5 days after receiving medications. The primary outcome was a postdose SCr increase > or = 0.5 mg/dL (44.2 micromol/L) over baseline. Secondary outcomes were a postdose SCr increase > or = 25%, a postdose estimated glomerular filtration rate decrease of > or = 25%, and the mean peak change in SCr. In 414 patients, contrast volume, presence of diabetes mellitus, use of N-acetylcysteine, mean baseline SCr, and estimated glomerular filtration rate were comparable in the 2 groups. SCr increases > or = 0.5 mg/dL occurred in 4.4% (9 of 204 patients) after iopamidol and 6.7% (14 of 210 patients) after iodixanol (P=0.39), whereas rates of SCr increases > or = 25% were 9.8% and 12.4%, respectively (P=0.44). In patients with diabetes, SCr increases > or = 0.5 mg/dL were 5.1% (4 of 78 patients) with iopamidol and 13.0% (12 of 92 patients) with iodixanol (P=0.11), whereas SCr increases > or = 25% were 10.3% and 15.2%, respectively (P=0.37). Mean post-SCr increases were significantly less with iopamidol (all patients: 0.07 versus 0.12 mg/dL, 6.2 versus 10.6 micromol/L, P=0.03; patients with diabetes: 0.07 versus 0.16 mg/dL, 6.2 versus 14.1 micromol/L, P=0.01). CONCLUSIONS: The rate of contrast-induced nephropathy, defined by multiple end points, is not statistically different after the intraarterial administration of iopamidol or iodixanol to high-risk patients, with or without diabetes mellitus. Any true difference between the agents is small and not likely to be clinically significant.  (+info)

Increasing contrast agent concentration improves enhancement in first-pass CT perfusion. (36/131)

BACKGROUND AND PURPOSE: Our aim was to evaluate whether increasing iodine concentration, at a constant total iodine dose, resulted in better brain tissue opacification in patients with acute stroke symptoms during their evaluation by first-pass CT perfusion (CTP). MATERIALS AND METHODS: One hundred two patients presenting to the emergency department within 3 hours of onset of acute stroke symptoms underwent CTP scanning. Three different concentrations of iodinated nonionic contrast material were used (300, 350, or 400 mg/mL). Total iodine dose (15 g) and injection rate (7 mL/s) were kept constant. There were 25, 53, and 19 patients in the different concentration groups, respectively; 5 patients were excluded due to uncorrectable motion artifacts. CTP scanning was performed at the level of the putamen, and data were analyzed by determining peak opacification for normal gray and white matter, arterial input, and venous output. Mean and SD values were calculated, and 3 concentration groups, stratified by region-of-interest location, were compared by using a single-tailed unpaired t test. RESULTS: Monotonic increasing peak opacification was observed in all region-of-interest locations. Statistically significant differences were observed between the 300 and 350 mg/mL, 300 and 400 mg/mL, as well as the 350 and 400 mg/mL groups (P<.01) in white matter, gray matter, and the arterial input. Statistical significance was seen in the venous output group between the 300 and 400 mg/mL (P<.005) and 350 and 400 mg/mL (P<.007) groups, but not between the 300 and 350 mg/mL (P=.2) groups. CONCLUSION: Increasing contrast concentration improves peak opacification of tissue, suggesting that CTP evaluation of patients with acute stroke is better performed with the highest available concentration contrast agent.  (+info)

Improved estimation of glomerular filtration rate by serum cystatin C in preventing contrast induced nephropathy by N-acetylcysteine or zinc--preliminary results. (37/131)

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Angiographic CT with intravenous administration of contrast medium is a noninvasive option for follow-up after intracranial stenting. (38/131)

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Prevalence of anatomical variants and coronary anomalies in 543 consecutive patients studied with 64-slice CT coronary angiography. (39/131)

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A high-precision contrast injector for small animal x-ray digital subtraction angiography. (40/131)

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