ABSTRACT
The objective of this case report is to determine the accurate localization of a malignant ventricular tachycardia (VT) focus by combining multichannel magnetocardiographic (MCG) information with morphologic data. The localization was obtained by calculating the three-dimensional current density distribution (3D-CDD) on the left ventricular surface. To estimate the accuracy of this localization technique, examinations of a healthy volunteer were additionally performed. The MCG-signals were recorded in a magnetically shielded room by a 49-channel magnetogradiometer. The corresponding morphologic information was recorded by magnetic resonance tomography (MRT). The coordinate systems were matched with the help of markers. The 3D-CDD was calculated by the Philips CURRY software package. The origin of a malignant VT determined by X-ray images of the ablation catheter position during the electrophysiological examination (EPE), was used as the gold standard. This was then compared with the localization results obtained by the 3D-CDD. It was found that the localization coordinates showed a difference of less than 10 mm.
Subject(s)
Image Processing, Computer-Assisted , Magnetics , Tachycardia, Ventricular/diagnosis , Adult , Electrocardiography , Electrophysiology , Female , Humans , Male , Tachycardia, Ventricular/physiopathologyABSTRACT
To evaluate the usefulness of cine-MRI for the quantitative assessment of aortic valve regurgitation, 31 patients (54 +/- 15 years of age; 22 M, 9 F) and 10 normal volunteers underwent a multi-modality imaging protocol comparing cine-MRI with color Doppler echocardiography and contrast aortography. Twenty-one patients had aortic regurgitation with an associated transvalvular gradient, 10 patients had pure valve incompetence. Aortic insufficiency as assessed by the signal void from regurgitant flow on cine-MRI was best analyzed on transversal tomograms. Both the volume of the signal void caused by turbulence above a threshold velocity, and the ratio of the diameters of the regurgitant jet and the outflow tract (dAL-Jet/DLVOT) were found to correlate closely with the (Seller's) angiographic regurgitant score by r = 0.86 each (p < 0.001), and the color Doppler echocardiographic index by r = 0.74 and 0.89, respectively (p < 0.001). Cine-MRI failed to differentiate the angiographic grades I and II, however, clearly separated grades II, III, and IV in contrast to other non-invasive imaging modalities. Moreover, a semiquantitative index derived from cine-MRI allowed a rapid assessment of the severity of regurgitation, similar to color Doppler echocardiography and the semiquantitative angiographic Seller's score. Thus, cine-MRI volumetric evaluation of transvalvular flow turbulences provides a useful and reproducible means to quantify aortic regurgitation. It also allows serial atraumatic investigations as a diagnostic alternative to color Doppler examination in patients less suitable for echocardiographic evaluation and may prove helpful in monitoring the natural course of aortic valve disease.
