[en] Three-dimensional data processing was developed for single photon computed tomographic imaging of the multigated blood pool with Tc-99m labelled red blood cells. A gamma camera was rotated from the left posterior oblique to the right anterior oblique projections at intervals of 180 deg/32. Data were collected at each part for one to two minutes, and the number of gates per beat was 12 to 20, depending on the patient. Three-dimensional transaxial images of the heart were reconstructed by the filtered back projection method without attenuation correction. A Shepp and Logan filter was used for the convolution filter. Short-axial images were reconstructed from the transaxial images. Using the equicount level method, the contours of both ventricles at each short-axial cross-section image were determined automatically with 50 % levels of the maximum counts. Each contour line was smoothed to the fifth order of Fourier function after conversion from (x-y) coordinates to (r-θ) polar coordinates with respect to the center of the area. Each contour line, converted again into (x-y) coordinates, was drawn successively on a color CRT at constant intervals and inclinations in order to display the ventricles three-dimensionally. It is possible to display simultaneously on a CRT the right and left ventricles or two types of cardiac disease. It is also possible to depict superimposed images of end-diastolic and end-systolic ventricles. The length of the long axis at end-systole in the normal case became less than half the length of the one at end-diastole. In the case of inferior infarction, the length of the left ventricular long axis did not change according to contraction, and akinesis at the inferior wall was clearly imaged. In the case of hypertrophic cardiomyopathy, the thickness of the interventricular septum was markedly increased compared to that of the normal. (J.P.N.)

[en] A case of left ventricular apical diverticulum with marked hypertrophy of the left ventricular apical wall revealed by thallium-201 myocardial emission CT is reported. A 23-year-old woman was admitted to our hospital for evaluation of chest oppression. She was known to have had a heart murmur soon after birth, but she grew uneventfully, partaking in normal exercise. At the age of 21, she began to feel chest oppression during exercise. As the attacks became frequent, she was admitted to our hospital. Physical examination revealed an ejection systolic murmur in the second left intercostal space. Electrocardiography showed ST depression and T inversion in leads III, a V_F and V_4-6. M-mode echocardiography was normal. Two-dimensional echocardiography showed a small diverticulum at the apex of the left ventricle, which was also recognized by left ventriculography. It was about 8 x 12 mm in size. Thallium-201 myocardial emission CT disclosed marked uptake in the apex of the left ventricle, suggesting apical hypertrophy. Stress thallium-201 myocardial emission CT was negative. Coronary angiography was normal. The cause of chest oppression in this patient is uncertain, but the small diverticulum and hypertrophy of the cardiac apex may play a role in its pathogenesis. (author)

[en] The clinical significance of the mode of left ventricular (LV) diastolic filling in hypertrophic cardiomyopathy was studied by the LV inflow velocity patterns (LVIF) of pulsed Doppler echocardiography and LV early diastolic filling rates (V₂) of radionuclide (RI) angiography. The relationship between the deceleration time (DT) obtained from LVIF and the V₂ was evaluated in 34 patients with nonobstructive hypertrophic cardiomyopathy (HCM) and in nine with obstructive hypertrophic cardiomyopathy (HOCM), and the results were compared with those of 10 patients with dilated cardiomyopathy (DCM), of two with restrictive cardiomyopathy (RCM), and of 19 normal subjects. HCM was subdivided into the following groups according to V₁-DT relationships: Group 1 with prolonged DT and decreased V₁, Group 2 with normal or short DT and normal V₁, and Group 3 with normal or short DT and decreased V₁. There were significant negative correlations between V₂ and DT in Groups 1 and 2 of HCM, normal and HOCM. However, there were significant positive correlations in Group 3 of HCM, DCM and RCM. Nearly all patients in Group 3 had decreased LV ejection fraction and % fractional shortening, distinct B-B' step formation of the mitral valve echogram, and huge A wave of the apexcardiogram. These findings suggested that the LV rapid filling interval gradually became shorter because the LV contraction is decreased as myocardial fibrosis develops in HCM, and that we must pay attention to the diagnosis of such abnormalities, similar to those of DCM or RCM. (author)

[en] Stress thallium-201 emission computed tomography (ECT) was performed for 24 patients. Three short-axis sections and one central long-axis section were selected for the circumferential profile curves. Redistribution (%) and washout (%) were calculated from the stress and redistribution profile curves in each section. These parameters were evaluated by comparison with regional wall motion on radiographic contrast ventriculography. Forty-eight of the 52 segments (92 %) with normal thallium uptake showed normal wall motion. Among the segments with abnormal thallium uptake, normal or hypokinetic wall motion was observed in 12 of 13 segments (92 %) with more than 20 % redistribution and in 16 of 19 segments (84 %) with 10-20 % redistribution, while it was observed in only 15 of 36 segments (42 %) without redistribution (p < 0.001). Among 48 infarcted segments, 16 segments (33 %) showed significant redistribution on ECT analysis. Normal or hypokinetic wall motion was observed in three of five segments (60 %) with more than 20 % redistribution, and in 10 of 11 segments (91 %) with 10-20 % redistribution, while it was seen in only eight of 30 segments (17 %) without redistribution (p < 0.005). Washout (%) was classified as normal (> 20 %), mildly decreased (10-20 %) and decreased (< 10 %) in each segment, but there was no correlation between % washout and regional wall motion in infarcted segments. We conclude that stress thallium ECT showing three-dimensional radionuclide distribution in the myocardium permits semi-quantitative evaluation of thallium redistribution and washout. Thallium redistribution was occasionally seen in infarcted segments on ECT analysis. Furthermore, any regional wall motion abnormality was milder in segments with redistribution than in those without redistribution, suggesting that thallium redistribution may be one of the signs of the viable myocardium. (J.P.N.)

[en] Nuclear magnetic resonance imaging was performed for 14 patients with aortic dissection using a 0.15T resistive magnetic imaging system (Toshiba MRT-15A). The diagnosis was comfirmed by X-ray computed tomography. The scan time was 15 minutes, and five or 10 slices were obtained simultaneously. The imaging was made using spin echo method (repetition time: T_R = 200 - 800 msec, and echo delay time: T_E = 40 msec). The natural contrast between flowing blood and stationary material permits the clear demonstration of the intimal flap of aortic dissection. The intimal flap was demonstrated in seven cases as a curvilinear high intensity band within the dilated aorta in consecutive sections. The rapidly flowing blood in the narrow true lumen produced little or no signal, while eddy currents within the false lumen usually produced signals. The thrombi in the false lumen had high intensity. In seven cases, the false lumen was completely filled with thrombi and the intimal flap could not be observed on nuclear magnetic resonance images. (author)

[en] Thallium-201 double dose scintigraphy was applied to exercise to estimate the coronary blood flow reserve of the left and right ventricles and this was compared with the degree of coronary artery stenosis. As an index of coronary reserve we measured the rate of change of blood flow distribution (ΔF) calculated from the change in myocardial radioactivity following thallium-201 injections, once at rest and once during exercise. With submaximal exercise the increases in ΔF of the left ventricle were less in patients with ischemic heart disease than in the control subjects, and were less as the number of diseased coronary vessels increased. The increases of ΔF of the right ventricle were less in patients with stenosis of the proximal portion of the right coronary artery than in patients without stenosis and in the control subjects. The more severe the stenosis of the proximal portion of the right coronary artery, the smaller the ΔF of the right ventricle. These results indicate that evaluation of the ΔF in the left and right ventricles is useful in estimating coronary artery stenosis. (author)

[en] Dipyridamole was infused intravenously at a rate of 0.142 mg/kg per min for four min, and a stress image was obtained 10 min after the injection of two mCi ²⁰¹Tl. The myocardial image of Tl was analyzed by single photon emission computed tomography and its washout rate was calculated by the segmental ROI method. Myocardial function and the motion of the left ventricular wall were analyzed by ^99mTc-RBC-gated cardiac pool imaging. Reverse redistribution was noted in 27 (21.6 %) of 125 consecutive Tl dipyridamole and redistribution myocardial imaging studies. The stress image demonstrated normal perfusion (group 1) and reduced perfusion (group 2) of Tl. Group 1 consisted of 17 patients with diabetes mellitus, supraventricular arrhythmias, hypertension, and others. Group 2 consisted of 10 patients with subendocardial infarction, diabetes mellitus, and hypertension, and others. The percentage prevalence of reverse redistribution among patients with supraventricular arrhythmia was 62.5 % (five of eight patients), with subendocardial infarction 60.0 % (three of five), with hypertension 42.8 % (six of 14), and with diabetes mellitus 40.0 % (eight of 20), while in those with transmyocardial infarction and angina pectoris no reverse redistribution percentage was found. The washout rate of Tl in normal perfusion areas was 44.0 ± 12.8 %, the reverse redistribution of group 1 was 47.4 ± 12.8 %, and of group 2 was 51.2 ± 8.2 %. The washout rate of the reverse redistribution of group 2 was significantly greater than that of the normal areas. In gated cardiac pool imaging, patients in group 2 had significantly larger areas showing abnormal contraction of the left ventricular wall and significantly lower ejection fraction than did group 1. In the electrocardiogram ST segment depression was noted more frequently in group 2 than group 1. No Q wave was present in the corresponding reverse redistribution area. (J.P.N.)

[en] For 52 patients with cardiac disease and 11 patients with vascular disease, In-111-oxine platelet scintigraphy was performed to assess its clinical usefulness for detecting thrombi. Using Hayashida's method, platelets were separated in 43 ml peripheral blood, washed and labeled with 1 mCi In-111-oxine. In addition to planar images in the anterior, 45 deg left anterior oblique and left lateral views, single photon emission computed tomography (SPECT) was performed in some cases by rotating a dual gamma camera 24 and 72 hours after labeled platelet injection. The functions of platelet and coagulability were examined 36 hours after the injection of labeled platelets. Medical therapy was not changed during this study. Intracardiac thrombi were documented in 16 of 52 cases with cardiac disease and intravascular thrombi in 10 cases with vascular disease by angiography, CT and two-dimensional echocardiography. Positive images were obtained in 10 cases with cardiac disease and in eight cases with vascular disease by scintigraphy. Therefore, sensitivity, specificity, and overall accuracy were 63 %, 100 % and 88 % in intracardiac thrombi; 80 %, 100 % and 82 % in intravascular thrombi; and totally 69 %, 100 % and 87 %, respectively. In the detection of intracardiac thrombi by scintigraphy, the sensitivity seemed to be lower and the specificity higher than those by other graphic studies. In 52 cases with cardiac disease, five out of six cases with false negative images had received antiplatelet and/or anticoagulant drugs, and in these cases, platelet and coagulation functions tended to be decreased compared with those of true positive cases or true negative cases. We conclude that positive images in scintigraphy indicate the existence of growing thrombi, and that In-111-oxine platelet scintigraphy has clinical usefulness, not only for detecting thrombi, but for estimating platelet activity and effect of medical therapy. (author)

[en] Digital subtraction angiography (DSA) has been adopted to detect ischemic myocardial areas and to quantitatively evaluate the degrees of myocardial perfusion abnormalities. Subtraction for selective coronary arteriography was performed sequentially between mask and enhanced images in the same cardiac phases by means of ECG signals. We obtained three distinct perfusion phases which we termed the arterial, capillary, and venous phases. Densitometry of the circumferential cardiac wall was performed on these sequential images. The results were compared with ²⁰¹Tl myocardial scintigrams and cine angiograms. In the arterial phase, the abnormalities of the coronary artery, such as stenosis, obstruction and collaterals were represented. In the capillary phase, contrast materials served as markers of myocardial perfusion and delineated infarctions as areas of low contrast enhancement compared to the normally perfused myocardium. In the venous phase, the infarcted areas were represented as areas with greater relative contrast enhancement than that of the normal myocardium. Circumferential analysis of perfusion could provide more detailed information about myocardial ischemic areas and the degrees of ischemia. Although we used invasive selective coronary arteriography, DSA techniques have numerous merits such as excellent temporal resolution, spatial resolution, and good contrast resolution, over conventional methods. Quantitative DSA methodology which we developed provided not only anatomical information about the main coronary arteries but new information about abnormalities of peripheral myocardial perfusion. (author)

[en] Nuclear magnetic resonance imaging (MRI) is a noninvasive method which can discriminate between flowing blood and vascular walls, and is expected to contribute to the diagnosis of cardiovascular diseases. Since the data acquisition by conventional MRI is too long for precise cardiac imaging, the ECG-gated method is mandatory in evaluating cardiac function and producing cardiac images of high quality. To evaluate the effectiveness of ECG-gated MRI, left ventricular wall motion and ejection fraction by MRI were compared with those obtained by radionuclide technique. Two types of MR imagers were used : one with a resistive magnet (0.15 Tesla) for 12 patients, and the other with a superconductive magnet (0.35 Tesla) for eight patients. MRI imaged cardiac muscle and vascular walls without the need for any contrast media or radionuclides. The superconductive apparatus provided better quality images than did the resistive one. Comparing MRI with radionuclide technique regarding left ventricular wall motion, resistive and superconductive MRI data correlated satisfactorily with those of radionuclide technique, except in the inferior wall, which was better evaluated by radionuclide technique. Left ventricular ejection fraction obtained by MRI was moderately lower than those obtained by radionuclide technique, though the correlation was good [r = 0.84 (resistive unit) and r = 0.85 (superconductive unit)]. In addition to three-dimensional morphological information, ECG-gated MRI provides information nearly comparable to that of radionuclide technique in the evaluation of left ventricular function and wall motion. Therefore, we regard gated MRI as effective in evaluating various aspects of cardiovascular diseases. (author)