Mit der Verbreitung von 'Geräten zur digi talen Subtraktionsangiographie (OSA) wurden die Möglichkeiten quantitativer Auswertungen stark erweitert, vor allem durch die direkte Verfügbarkeit der d igi ta len Bilder für eine Messung. Die Wartezeit bis zur Fi Inientwicklung entfällt. Anamnesedaten, physiologische Daten wie die Herzrate und Kalibrierdaten können ebenfalls unmittelbar in Berechnungen und Reports einfließen. Wenn ein Auswerteverfahren gut zu bedienen und in der Berechnung hinreichend schnell ist, kann die Auswertung bei einem DSA-Gerät während der Untersuchung erfolgen, vor a l lem, weil die Rückkehr zur Durchleuchtung mit digitaler Speicherung des letzten Bildes oder zur weiteren Szenenaufnahme jederzeit möglich ist. Die häufigere Anwendung der Meßverfahren führte gerade bei der Auswertung des angiographisch dargestellten linken Ventrikels zur Entwicklung verfeinerter und neuer Methoden. Zur Beurteilung der globalen Funktion und zur Bewertung der regionalen Kontrakt!l itat bildeten sich teils konkurrierende, teils unter einer speziellen Fragestellung eindeutig indizierte Verfahren heraus, welche ein Nachlassen bzw. eine vorliegende mangelhafte Pumpleis tung des l inken Ventrikels mit Maß und Zahl belegen. Im SiemensPOLYTRON ® wird versucht, für al le diese Fragen eine Antwort zu geben.

The angiographic assessment of left ventricular volume (LV) and ejection fraction (EF) by means of the area-length method (ALM) is based upon geometric assumptions, which might lead to erroneous results. With the development of digital subtraction angiocardiography in real-time, densitometric procedures of calculating left ventricular parameters can be used on-line. This study examines both reliability and accuracy of a densitometric technique for evaluating LV and EF in comparison to the single-plane ALM. Contrast images of heart casts and left ventricular angiograms of 54 patients suffering from different cardiac diseases were obtained by the image acquisition and processing system Polytron 1000 VR (Siemens AG, Erlangen, FRG). Digital images of both heart casts and patients were evaluated densitometrically and geometrically by two independent observers. In the phantom study the densitometric method exhibited a significantly (p < 0.01) better agreement with the true values than the ALM. The evaluation of left ventricular angiograms in patients comparing densitometry with the ALM demonstrated a relatively high residual deviation (enddiastolic volume Syx = +/- 27 ml, endsystolic volume Syx = +/- 19.4 ml). This is mainly due to systematic, method-related errors of densitometry and the morphometric technique. The intra- and interobserver variability in calculating EF showed a significantly (p < 0.05) smaller residual deviation for densitometry than for ALM; no significant differences were found for the calculation of LV. In conclusion, we demonstrated that the presented densitometric technique offers an objective and simple means of determining LV and EF with comparable reliability and validity to the area-length method.

Monoplane 30/spl deg/ RAO area-length-method (ALM) measurements of enddiastolic and endsystolic left ventricular volumes and ejection fraction are based on geometric assumptions which may lead to erroneous results. Densitometric evaluation is an alternative on-line method when applied to digital imaging and is independent of ventricular shape. The value and limitations of densitometry are demonstrated in heart casts and in 54 patients. Densitometric evaluation exhibited a better agreement with true values in the phantom study than the ALM. The intra- and interobserver variability was remarkably lower for densitometry than for ALM. The presented data indicate that densitometry offers the potential for an objective and simple means of determining left ventricular volumes and ejection fraction during cardiac catheterization for digital imaging acquisition and processing systems.<>

The densitometric and geometric method for estimating the left ventricular ejection fraction (EF) are compared and the accuracy and reproducibility of densitometry in patients and casts are assessed. EF calculations for the densitometric method are in a better agreement with the simulated EF in the heart casts than the area-length method. The intra- and inter-observer variability is remarkably lower for the densitometry than for the area-length method. The data indicate that the densitometric calculation of EF is a more reliable method than the area-length method, because densitometry is independent of geometric assumptions.<>

Cardiac angiograms are preferably imaged jn orthogonal so-called biplane views. In such image pairs the vessels do not resemble each other to such a degree that correspondences between them can be derived directly. Direct computer matches on the basis of similarity have been used for closer angles like 15 or 20 degrees [9 In this recent study model knowledge for each of the standardized angio-projections is used to recognize the vessels in each view. After these two matches for identification the third dimension can be calculated using the fixed and known relation of the orthogonal vascular models. 1.