Ernest Byrom

Sequential regional phase mapping of radionuclide gated biventriculograms in patients with left bundle branch block

Phase analyses of biventricular radionuclide (RNA) gated studies were carried out in seven patients with normal conduction and in eight patients with left bundle branch block, (LBBB) all without significant abnormalities of hemodynamics or ventricular wall motion. The first Fourier harmonic of time-activity variation in each pixel was computed and displayed as an ampiltude image, a phase image, and a phase distribution histogram. In addition, automatically determined areas of earliest and latest phase for each ventricle were examined and compared. Qualitative analysis revealed relatively uniform distribution of phase across both ventricles in patients with normal conduction, but markedly delayed phase in the left ventricle (LV) of patients with LBBB. In addition, the location within the ventricles of areas of earliest and latest phase was somewhat different for the two groups, the most prominent finding being an area of earliest LV phase along the interventricular septum seen in seven of eight patients with LBBB but in none of the normal conduction patients. Quantitatively, relative measures of mean, early, and late phase calculated by subtracting respective RV from LV values of phase to give ΔMean, ΔEarly, and ΔLate showed marked LV phase delay in LBBB patients. Values of these parameters (normal conduction vs LBBB, mean ± SD) were ΔMean (−5 ± 2 vs 36 ± 9 degrees, p p = 0.0001), and ΔLate (−7 ± 8 vs 35 ± 11 degrees, p

Radionuclide regurgitant index: Value and limitations☆

The radionuclide regurgitant index, defined as left ventricular/right ventricular stroke counts obtained from gated equilibrium studies, has been reported to predict the presence and severity of left-sided valve regurgitation. This study evaluated the radionuclide regurgitant index in 100 patients in whom left-sided valve regurgitation was angiographically graded (0 to 4+) with regard to most severe mitral or aortic regurgitation. Regurgitation was graded 0 in 44 of the 100 patients, 1+ in 22, 2+ in 8, 3+ in 6 and 4+ in 20. The radionuclide regurgitant index was 0.9 to 1.5 in 51 patients, 1.6 to 2.4 in 23 and 2.5 to 12.0 in 26. The mean radionuclide regurgitant index was 1.34 in the group with no regurgitation and 1.60 in those with 1+, 2.01 in those with 2+, 2.80 in those with 3+ and 3.85 in those with 4+ regurgitation. There was a significant difference (p less than 0.05) in the radionuclide regurgitant index between patients with no regurgitation and each group with regurgitation and between groups with regurgitation separated by two or more grades of angiographic regurgitation. Twelve patients had a discordant radionuclide regurgitant index; their index either predicted clinically significant or severe regurgitation when they had no or trivial regurgitation, or predicted no or trivial regurgitation when they had clinically significant regurgitation. Eight of 10 patients with a left ventricular ejection fraction of less than 0.30 had a discordant index (p less than 0.0005). All three patients with mitral valve prolapse associated with frequent ventricular extrasystoles had a discordant index (p less than 0.0005).

Sequential regional phase mapping of radionuclide gated biventriculograms in patients with sustained ventricular tachycardia: Close correlation with electrophysiologic characteristics

Radionuclide (RNA) gated studies were performed during sinus rhythm and during spontaneous or induced sustained ventricular tachycardia (VT) in six patients with clinical VT. Fourier analysis of time-activity variation was used to calculate a RNA phase value for each pixel in the image. Color coding of each pixel according to its calculated phase resulted in a RNA phase map of the ventricles. The following results were considered to be consistent with the known electrophysiology of VT: (1) the phase map correlated with QRS morphology and axis in most but not all tachycardias; (2) earliest phase usually demonstrated the VT origin to be at the border of the ventricular wall motion abnormality; (3) endocardial mapping (available in one patient) showed close correlation with RNA phase mapping; (4) in three patients with ischemic heart disease, VT with left bundle branch block (LBBB) pattern had earliest LV phase along the septum; and (5) for one patient imaged during two different VT morphologies, the tachycardias had earliest phase at different borders of the same wall motion abnormality with differing progression of phase across the ventricles. RNA phase mapping of VT is feasible and appears to provide data consistent with the electrophysiology of this arrhythmia.

Detection and quantification of regional wall motion abnormalities using phase analysis of equilibrium gated cardiac studies.

Phase images obtained from equilibrium gated cardiac studies were evaluated for qualitative and quantitative information and correlated with contrast angiography in 33 patients. The left ventricular region of interest was obtained by a semiautomatic procedure which avoided underestimation of size but also eliminated extraventricular pixels. Phase images and phase distribution histograms were arranged in three standard displays which included the whole heart, isolated left ventricle, isolated abnormal areas, and quantification of maximum phase shift in the whole free border and in the inferolateral and posterolateral segments. Only the free left ventricular border was evaluated. According to contrast angiography results, four categories were obtained: normal, hypokinetic, akinetic, and dyskinetic. The best correlation with contrast angiography was found with the results obtained by dividing the left ventricular free border in two segments (r = 0.91). Scheffes test for multiple comparisons showed significant differences between each of the four categories. Expressed in phase shifts from the histogram mode, the lower limits for the three abnormal categories were established at 30°, 78°, and 156° respectively for hypokinetic, akinetic, and dyskinetic segments. For distinguishing normal from abnormal segments, sensitivity = 83%, specificity = 94%, and accuracy = 89%. The main reasons for discrepant results appeared to be small hypokinetic areas in an otherwise normal ventricle, very large area of hypokinesia, segments adjacent to an area of marked abnormality, and ventricles with asynchrony (wave-like motion). The method described provides an image which characterizes myocardial synchrony, generates clear boundaries for abnormal areas, and lends itself to quantification.

Assessment of left ventricular function by radionuclide angiography during induced supraventricular tachycardia

Electrocardiographically synchronized radionuclide angiography was performed before, during and after induced paroxysmal supraventricular tachycardia in 13 patients. Data were acquired with a computer-interfaced Anger camera in a left anterior oblique projection. No data were acquired during tachycardia until tachycardia had been sustained for 1 minute. Patients ranged in age from 20 to 64 years (mean +/- standard deviation 42 +/- 14.5). Three patients had organic heart disease and 10 did not. Baseline and tachycardia heart rates (beats/min) were 59 to 99 (73 +/- 11) versus 141 to 228 (157 +/- 22). Baseline and tachycardia left ventricular measurements (mean +/- standard error) were as follows: ejection fraction 64 +/- 2 versus 62 +/- 4 percent (not significant), ejection rate 3.0 +/- 0.1 versus 4.3 +/- 0.4 mean ventricular counts/s (p less than 0.001), normalized end-diastolic counts 72.7 +/- 7.8 versus 48.7 +/- 6.7 X 10(3) counts (p less than 0.001), normalized stroke counts 37.1 +/- 3.4 versus 23.3 +/- 2.7 X 10(3) counts (p less than 0.001) and normalized count cardiac output 2,717.5 +/- 273.0 versus 3,620.2 +/- 403.7 X 10(3) counts/min (p less than 0.005). Although ejection fraction for the whole group did not change significantly, it decreased during tachycardia by 5 percentage points or more in five patients. These were the three patients with heart disease and the two normal patients with the fastest heart rate during tachycardia (228 and 214 beats/min, respectively). In summary, paroxysmal supraventricular tachycardia was characterized by a marked decrease in left ventricular end-diastolic and stroke volumes but increased ejection rate and cardiac output without significant change in ejection fraction. Heart disease or rapid heart rate during tachycardia appeared to have a deleterious effect on ejection fraction.

Spatiotemporal filtering of digital angiographic image sequences corrupted by quantum mottle

A method is described for the spatio-temporal filtering of digital angiographic image sequences corrupted by simulated quantum mottle. An x-ray dosage reduction in coronary imaging studies inevitably leads to the introduction of quantum mottle --a Poisson distributed, signal dependent noise that occurs as a result of statistical fluctuations in the arrival of photons at the image intensifier tube. Although spatial filtering of individual frames in the sequence is often performed to improve image quality, this technique does not utilize valuable information from temporal correlations between images. The spatio-temporal filter here estimates motion trajectories for individual pixels and then filters along the direction of motion. This method is different from temporal filtering techniques that do not use motion compensation as the latter always blur the edges of the coronary arteries. Although the method is derived for the estimation of a single frame from two degraded frames of a sequence, it is easily generalized to multi-frame estimates. The performance of the above filter is examined using real image sequences corrupted by quantum mottle.

Equilibrium Radionuclide Gated Angiography in Patients With Tricuspid Regurgitation

Equilibrium gated radionuclide angiography was performed in 2 control groups (15 patients with no organic heart disease and 24 patients with organic heart disease but without right- or left-sided valvular regurgitation) and in 9 patients with clinical tricuspid regurgitation. The regurgitant index, or ratio of left to right ventricular stroke counts, was significantly lower in patients with tricuspid regurgitation than in either control group (range and mean +/- standard error of the mean 0.4 to 1.0, 0.7 +/- 0.1 versus 1.0 to 1.5, 1.3 +/- 0.1 and 1.0 to 2.9, 1.5 +/- 0.1, respectively, p less than 0.001). Time-activity variation over the liver was used to compute a hepatic expansion fraction which was significantly higher in patients with tricuspid regurgitation than in either control group (1.4 to 11.4, 5.8 +/- 1.0% versus 0.6 to 3.4, 1.9 +/- 0.3% and 1.0 to 5.1, 2.3 +/- 0.2%, respectively, p less than 0.001). Fourier analysis of time-activity variation in each pixel was used to generate amplitude and phase images. Only pixels with values for amplitude at least 7% of the maximum in the image were retained in the final display. All patients with tricuspid regurgitation had greater than 100 pixels over the liver automatically retained by the computer. These pixels were of phase comparable to that of the right atrium and approximately 180 degrees out of phase with the right ventricle. In contrast, no patient with no organic heart disease and only 1 of 24 patients with organic heart disease had any pixels retained by the computer. In conclusion, patients with tricuspid regurgitation were characterized on equilibrium gated angiography by an abnormally low regurgitant index (7 of 9 patients) reflecting increased right ventricular stroke volume, increased hepatic expansion fraction (7 of 9 patients), and increased amplitude of count variation over the liver in phase with the right atrium (9 of 9 patients).