| Abstrakt: |
A new radionuclide method, called the ‘geometric count based’ GCB method, has been developed for the quantification of absolute left ventricular volume. As the method is based on planar radionuclide ventriculography, it is noninvasive and simple, and avoids the relatively cumbersome and longer lasting, dynamic procedure using single photon computed emission tomography, which can be used for achieving the same goal. The purpose of this study was to describe the exactness of the theoretical approach to the method and validate its accuracy both by physical experiments and the initial clinical trial, as compared to contrast ventriculography. Count based data were combined with the geometric based data assuming an ellipsoid left ventricular shape with identical short axes. The following equation for computing left ventricular end diastolic volume, EDV in ml was developed EDV 2cMCtotCmax, where c is the manually drawn short axis one row pixel ROI of the prolate ellipsoid in LAO 45° cm, M is the calibrated pixel size in cm2, Ctotis the total counts in LV ROI, and Cmaxis the maximum pixel counts in the LV ROI. Physical experiments with two different ‘heart shaped’ phantoms were used to compare the results obtained by the GCB method with the true phantom volumes and with the method assuming LV ball shape BLV, developed by other authors. The true volumes of cylindrical and ellipsoid phantoms of 112.5 ml and 190.5 ml were computed to be 114 ml and 196 ml by the GCB and 168 ml and 180 ml by the BLV methods, respectively. In a clinical study, GCB volumes were compared to volumes measured by using single plane contrast ventriculography in 38 coronary patients. A good correlation between the GCB method and contrast ventriculography was obtained both for EDV and end systolic ventricular volumes r0.94, r0.90. Both phantom and initial clinical studies indicate that the GCB method is an accurate, noninvasive and simple radionuclide method for measuring left ventricular volumes. Additionally, it could be used even in the smallest nuclear medicine units, for example in intensive care units where there are mobile cameras. © 2003 Lippincott Williams & Wilkins |
