Magda Kusus

Variability of Repeated Coronary Artery Calcium Measurements by Electron Beam Tomography

In 120 patients, the mean interscan variability of coronary calcium quantification by electron beam tomography was 19.9% (median 7.8%) for the traditional calcium score, and 16.2% (median 5.7%) for volumetric scoring. Although this difference was not significant, there was a significant influence of the total amount of calcium, number of acquired images, and image noise on interscan reproducibility.

Overlapping cross-sections significantly improve the reproducibility of coronary calcium measurements by electron beam tomography: a phantom study.

Purpose We conducted phantom studies to investigate whether overlapping cross-sections and volumetric scoring would significantly improve interscan reproducibility of electron beam tomography (EBT) for coronary artery calcium quantification. Method Fifteen phantoms simulating various amounts of coronary calcification were scanned in five different positions with a slice thickness of 3.0 mm and a table feed of 3.0, 2.5, and 2.0 mm. For the conventional “Agatston score” and a “volume score” (total volume of calcified lesions), interscan variabilities were compared between the three image acquisition protocols. Results Agatston score variability was significantly lower for the 2.0 mm table feed than for the 3.0 or 2.5 mm table feed (3.0 mm: 22.9 ± 10.3%; 2.5 mm: 13.6 ± 8.2%; 2.0 mm: 8.9 ± 5.5%). Volume score variability was significantly lower for 2.5 and 2.0 mm table feed than for 3.0 mm table feed (3.0 mm: 21.7 ± 11.0%; 2.5 mm: 10.9 ± 5.9%; 2.0 mm: 9.8 ± 5.9%). Conclusion Overlapping cross-sections, especially in combination with volumetric scoring, significantly improved interscan reproducibility of EBT calcium quantification in a phantom study.

PMN/Platelets Coinfused in Guinea Pig Hearts Exposed to Low-Flow Ischemia Have no Additive Cardiodepressive Effect

Recent studies revealed an additive cardiodepressive effect of polymorphonuclear granulocytes (PMN) and thrombocytes in hearts exposed to a no-flow ischemia. To find out whether or not this is also true for isolated guinea pig hearts exposed to a low-flow ischemia, the current study was performed. PMN or thrombocytes, together or separately, were applied as a 1-min bolus (1,000/µl or 20,000/µl, respectively) during ischemia or in reperfusion in the presence of thrombin (0.3 U/ml perfusate). Recovery of external heart work and intracoronary cell retention were quantified in percent. Sole application of PMN or platelets during ischemia and reperfusion significantly compromised myocardial function, whereas coapplication of PMN and platelets did not exhibit any further cardiodepressive effect. Coapplication of cells almost prevented intracoronary platelet retention during ischemia and in reperfusion, as opposed to sole platelet application. Known blockers of endogenously released anti-platelet substances like nitric oxide, PGI2 or adenosine did not mediate a further aggravation of myocardial dysfunction. The platelet-activating factor (PAF) antagonist WEB 2170 BS, however, significantly improved recovery of external heart work during ischemia and in reperfusion. This indicates that an additive cardiodepressive effect of PMN and platelets in working guinea pig hearts exposed to a low-flow ischemia, cannot be demonstrated, whereas PAF antagonists seem to be cardioprotective, under these conditions. Even addition of fibrinogen to the perfusate, did not show an additive cardiodepressive effect of coapplication of PMN and platelets.