[Comparison of 99mTc-hexakis 2-methoxy-2-isobutyl isonitrile and 201Tl SPECT imaging for evaluation of coronary artery disease]

To evaluate clinical value of 99mTc-hexakis 2-methoxy-2-isobutyl isonitrile (MIBI) imaging for assessing coronary artery disease (CAD), 99mTc-MIBI SPECT imaging at post-exercise and at rest was compared with 201Tl SPECT imaging at post-exercise and 3 hours redistribution in 27 patients suspected with CAD. The sensitivities for detecting CAD patients were 94% (17/18) by both studies. The specificities were 71% (5/7) by 99mTc-MIBI and 57% (4/7) by 201Tl (p = NS). The sensitivities for detecting stenosed coronary arteries (greater than or equal to 75% stenosis) were also similar between 99mTc-MIBI (78%) and 201Tl (74%) (p = NS). The similar specificity values were obtained by 99mTc-MIBI (84%) and by 201Tl (82%) (p = NS). The patterns of abnormality (normal, ischemia and scar) were similar between 99mTc-MIBI and 201Tl images in 22 of the 25 cases (88%) and 117 of the 125 segments (94%). However, these patterns were occasionally different particularly in patients who received PTCA or CABG. Thus, 99mTc-MIBI SPECT imaging seems to be as accurate as 201Tl SPECT imaging for the detecting and evaluating CAD.

Analysis of limiting factors of DNA band separation by a DNA sequencer using fluorescence detection

The factors affecting the electrophoretic separation of DNA bands in DNA base sequencing using fluorescence detection are analyzed. All the factors contributing to DNA band spacing and band width are evaluated; DNA diffusion and thermal effects on gels are the main considerations. The dependence of the gel's electrical resistivity on gel temperature and the variation of temperature over gel thickness are associated with a broadening of DNA band width. As a result of the analyses the maximum separable base number is represented as a function of various electrophoretic variables. The best separations are possible with an electric field strength corresponding to gel thickness. The maximum separable base number increases as the gel thickness decreases. It also increases as the migration distance increases, but it becomes saturated and has an upper limit when the migration distance is long. This upper limit increases as gel thickness decreases. DNA fragments with 600 and 601 bases can be completely separated from each other under optimum conditions for a 0.2 mm thick gel plate. Furthermore, using the band spacing information, under the same conditions, 750 bases could be assigned separately.

Effects of cardiac sympathetic nervous system on the stunned myocardium experimental study with 123I-metaiodobenzylguanidine

123I-Metaiodobenzylguanidine (123I-MIBG) uptake in the stunned myocardium was investigated in open chest dogs. 123I-MIBG is a tracer taken up in presynaptic adrenergic vesicles and reflects the function of the myocardial sympathetic nervous system. This study revealed that in the stunned myocardium without infarct, 123I-MIBG uptake was normal up to 40 minutes of ischemia and that exogenous noradrenaline improved deteriorated regional wall motion with increased uptake of 123I-MIBG. However, uptake of 123I-MIBG per flow decreased with infarct in ischemic areas, and it showed a linear relation with regional wall motion. Thus, in the absence of infarction 123I-MIBG is a tracer to differentiate stunning from more severe ischemia with persistent wall motion abnormality. Normal uptake and storage of 123I-MIBG in the stunned condition suggests that catecholamine release or second effector mechanism may relate to the mechanism.

Metabolic reserve in normal myocardium assessed by positron emission tomography with C-11 palmitate

Positron emission tomography (PET) with C-11 palmitate has been used in estimating the myocardial utilization of free fatty acid. To assess the metabolic reserve in normal subjects, a PET study was performed at control and during dobutamine infusion at 2 hour intervals in 5 normal subjects. Following monoexponential curve fitting of the time activity curve of the myocardium, the clearance half time (min) and residual fraction (%) were calculated as indices of beta-oxidation of free fatty acid. A significant increase in the heart rate and systolic blood pressure were observed during dobutamine infusion (65 +/- 5 vs 100 +/- 29 bpm, p less than 0.05 and 119 +/- 12 vs 144 +/- 16 mmHg, p less than 0.01, respectively). The clearance half time and the residual fraction were significantly decreased (23.4 +/- 2.6 vs 15.8 +/- 2.3 min and 67.0 +/- 2.5 vs 58.6 +/- 4.0%, P less than 0.05, each). When the left ventricular myocardium was divided into 4 segments, these indices were similar at control and uniformly decreased without regional differences during dobutamine infusion. These data suggest that beta-oxidation of free fatty acid may be uniformly increased in the left ventricular myocardium in relation to the increase in cardiac work in normal subjects. PET with C-11 palmitate at control and during dobutamine infusion is considered to be promising in assessing metabolic reserve in the myocardium.

Real Time Automated Simultaneous Double-Stranded DNA Sequencing Using Two-Color Fluorophore Labeling

We determined the base sequences of both strands of duplex DNA simultaneously with an automated DNA sequencer. Primers for each strand were labeled with two different dyes and chain extension reactions for both strands produced four DNA families: "A", "C", "G", and "T". An image splitting-prism and band-pass filters were mounted on a real time DNA sequencer to detect fluorescences from the two different dyes separately. As a result, one thousand bases of a clone could be determined at the same time.

[A bull's eye subtraction polar map for assessing thallium redistribution (1). Comparison with quantitative redistribution]

A new bull's eye subtraction polar (BS) map has been developed for quantitative assessment of redistribution on stress-delayed thallium-201 SPECT studies. BS map was created after subtraction of a normalized stress bull's eye polar map from a normalized delayed polar map in 10 normal subjects and 33 patients with coronary artery disease to compare BS map with qualitative redistribution scores. The BS map showed less than 15% in all of the 50 segments in the normal subjects. Of 27 segments exhibiting persistent defect without redistribution, the BS map showed less than 10% in 20 segments (74%) and 10-15% in 6 segments (22%). On the other hand, of 34 segments exhibiting redistribution, the BS map showed greater than or equal to 15% in 25 segments (74%) and 10-15% in the remaining 9 segments (26%). Thus, significant redistribution was evident in the areas showing greater than or equal to 10-15% on the BS map. We conclude that the BS map is valuable for quantitative assessment of redistribution on stress-delayed thallium-201 SPECT imaging.

Regional wall thickening of left ventricle evaluated by gated positron emission tomography in relation to myocardial perfusion and glucose metabolism

Regional wall thickening was assessed by electrocardiographically gated positron emission tomography (ECG-gated PET) in 26 patients with coronary artery disease. The standardized percent count increase from end-diastole to end-systole (S-percent Cl) was calculated as an index of wall thickening. The S-percent Cl was 77.8% +/- 28.9% in the segments with normal perfusion at rest, 51.9% +/- 29.5% in those with mild hypoperfusion, and 32.8% +/- 30.9% in those with severe hypoperfusion (p less than 0.001, each). Among the segments with resting hypoperfusion, the S-percent Cl was 38.9% +/- 31.5% in those without stress-induced ischemia and 48.7% +/- 30.9% in those with ischemia (p less than 0.05). Furthermore, among resting severe hypoperfusion, the S-percent Cl was 23.0% +/- 23.9% in the segments without fluorine-18-fluorodeoxyglucose (FDG) uptake and 37.8 +/- 32.9% in those with FDG uptake (p less than 0.05). These results suggest that stress-induced ischemia and FDG accumulation correlated with wall thickening. Thus, quantitative analysis of regional wall thickening seems to be useful for combined analysis of regional function, perfusion and metabolism in coronary patients.

Metabolic activity in the areas of new fill-in after thallium-201 reinjection: comparison with positron emission tomography using fluorine-18-deoxyglucose

Reinjection of thallium-201 after recording the 3-hr delayed scan often demonstrates improvement in areas of persistent abnormalities. To determine the metabolic activity of these areas, the changes seen on stress/redistribution/reinjection thallium SPECT were compared with PET using fluorine-18-fluorodeoxyglucose (FDG) in 18 patients with coronary artery disease. Of 48 segments showing no redistribution on the delayed scan, the reinjection scan identified new fill-in in 20 segments (42%), all of which demonstrated FDG uptake. In contrast, only 7 of the 28 segments (25%) showing no fill-in after reinjection were PET viable (p less than 0.01). Eleven patients had coronary bypass graft surgery after the radionuclide study. The majority of the segments showing redistribution (87%) and new fill-in after reinjection (65%) improved in wall motion, whereas only eight segments (25%) without new fill-in improved after surgery. Of those without new fill-in, two segments showing PET ischemia improved in wall motion, whereas the remaining six segments showing PET scar did not improve after surgery. Thus, the segments showing new fill-in after reinjection are PET viable myocardium. However, reinjection thallium imaging still underestimates the extent of tissue viability compared to PET imaging.

Evaluation and clinical use of early washout ratio of thallium-201 in normal and ischemic myocardium after dipyridamole-induced vasodilation using ring-type emission computed tomography

Using newly developed ring-type emission computed tomography (SPECT), we investigated the washout ratio (WR) of T1-201 in the myocardium quantitatively with fast dynamic scanning after infusion of dipyridamole (0.57 mg/kg), and assessed the feasibility of early WR as a marker to detect coronary artery disease. Twenty-three patients with and 8 patients without coronary artery disease had serial SPECT images obtained every 5 min for 45 min and at 180 min after dipyridamole and subsequent T1-201 injection. The best appropriate transaxial slice was selected for WR analysis. Most appropriate diagnostic time was 25 min after infusion of T1-201 (WR-25). Normal WR-25 was 7.1 +/- 4.0%, 5.9 +/- 3.1% and 7.1 +/- 2.3% at the septum, anterior and lateral wall, respectively. Sensitivity, specificity and accuracy to identify coronary stenosis greater than 50% with a usage of abnormal WR-25, defined as WR-25 less than (mean of normals--1SD) in each region of inferest of the left ventricle (LV), were 96%, 100% and 97%, respectively. These results were better than those achieved by visual analysis (sensitivity 78%, specificity 100%, accuracy 84%). In patients with single as well as multivessel disease, the regional accuracy in assessing stenosis of more than 50% in the left anterior descending artery (LAD) and left circumflex artery (LCX) by WR-25 was 94% and 83%, respectively, which was significantly better than using visual methods (LAD 72% and LCX 50%; p less than 0.05). Thus, evaluation of early washout ratios (WR-25) after dipyridamole injection is a valuable method to increase sensitivity in assessing regional myocardial perfusion abnormality and is helpful in detection of ischemic heart disease, even with multivessel disease.

Chemical robot for enzymatic reactions and extraction processes of DNA in DNA sequence analysis

A chemical robot capable of performing enzymatic reactions and extraction processes of DNA has been developed. The basic functions of this robot include handling of plastic tubes with caps, micropipetting, mixing, microcentrifuging and incubating. As a result, almost all of the pre-electrophoresis steps can be carried out. In addition, because these processes are automated, the working time of each process can be reduced. The reproducibility of the automated operation is equivalent to that of a skilled operator.

Cardiac sports rehabilitation for patients with ischemic heart disease

This paper summarizes data gathered from an 8 years sports cardiac rehabilitation program at Kyoto University and satellite hospital (Takeda Hospital). In total, 185 patients were rehabilitated under our original program with no serious cardiac accidents. Compliance was 58.2% after 6 months of this rehabilitation. In patients selected to evaluate the value of rehabilitation, exercise study with treadmill and 201Tl scintigraphic study showed improvement in exercise tolerance (in 58% of patients) and in perfusion on exercise (in 40%). Coronary angiographic study showed regression of arterial narrowing in 16% of the patients studied. We conclude that in addition to emotional and psychological support, our sports cardiac rehabilitation is safe and effective in improving exercise tolerance and cardiac perfusion.

Significance of fill-in after thallium-201 reinjection following delayed imaging: comparison with regional wall motion and angiographic findings

To identify reversible defects, reinjection of a small amount of thallium-201 (201Tl) following 3-hr delayed imaging was performed in 60 patients with coronary artery disease who had perfusion abnormalities on their post-exercise 201Tl images. Thallium-201 uptake was visually scored and judged as normal (Group 1), reversible defect (Group II), new fill-in after reinjection (Group IIIa) and no fill-in even after reinjection (Group IIIb). New fill-in after reinjection was observed in 27 segments of the 85 segments (32%), showing persistent defect on the stress and delayed images. The wall motion in Group IIIa was worse than Group II but better than Group IIIb. Group IIIa showed Q-wave on ECG more often (69%) than Group II (27%) (p less than 0.01), but less often than Group IIIb (85%) (p less than 0.05). These data indicate that the reinjection 201Tl imaging often identifies new fill-in in the areas of no redistribution on the delayed images and it may hold promise for assessing tissue viability which the conventional imaging may underestimate.

Effects of nifedipine on cardiac function in patients with coronary artery disease evaluated with ambulatory radionuclide monitoring

The effects of nifedipine on left ventricular function were evaluated in 17 patients with coronary artery disease with an ambulatory radionuclide detector (VEST). Hemodynamic data were recorded continuously at rest and during upright bicycle ergometer exercise before and 30 minutes after 10 mg of oral nifedipine administration. The heart rate increased and the resting systolic blood pressure decreased significantly with nifedipine. The end-diastolic and end-systolic volumes during exercise were significantly reduced and EF increased during exercise after nifedipine administration. These salutary hemodynamic responses of nifedipine appear to be beneficial for patients with effort angina pectoris.

[Evaluation of complete left bundle branch block with normal coronary artery using positron emission CT (PET) and Tl-201 scintigraphy]

False-positive Tl-201 scintigraphy in patients with complete left bundle-branch block (CLBBB) and normal coronary artery had been reported by several authors. However the reason for this phenomenon remained to be clarified. We investigated 2 patients (case 1; a 65-year-old male, case 2; a 58-year-old male) with CLBBB using positron emission computed tomography (PET). Coronary angiography revealed normal coronary artery in both cases. In both cases, Tl-201 stress scintigraphy demonstrated definite perfusion defect at the anteroseptal region without redistribution, although PET study using F-18 fluorodeoxyglucose (18F-FDG) revealed defect at the septal wall. This indicates that perfusion defect detected by Tl-201 scintigraphy relates rather not to ischemic myocardium with a viable region, but to necrotic or fibrous tissue. Thus, PET is a useful tool in investigating viability of abnormal myocardium when other study has failed to do so. Our cases with CLBBB suggested that there was abnormal flow and metabolism at the anteroseptal region, possibly relating to the pathogenesis of CLBBB.

[Evaluation of antihypertensive therapy by ambulatory blood pressure monitoring and establishment of the level of antihypertensive goal on the circadian rhythm of blood pressure]

We have developed a new method for the evaluation of antihypertensive therapy on the circadian rhythm of blood pressure and attempted to determine the indications for antihypertensive therapy and the level of antihypertensive goal. Blood pressures were measured for 24 hours by the use of ambulatory blood pressure monitoring using 630 (ABPM-630) in 50 normotensives, 50 untreated hypertensives and 50 hypertensives undertreatment with various antihypertensive drugs (110 males and 40 females, with a mean age of 53.4 +/- 13.3 yrs). Blood pressure profiles were prepared for determination of the hyperbaric and hypobaric indexes. According to the WHO's definitions for blood pressure, the hyperbaric index was defined as the area above 140 mmHg in systolic blood pressure or 90 mmHg in diastolic blood pressure, and the hypobaric index, as the area below 100 mmHg or 60 mmHg, respectively. The criteria of the hypobaric index was obtained from the mean basal blood pressure (the lowest blood pressure during sleep) of the 50 normotensives. The mean hyperbaric index of the 50 normotensives was 20.4 +/- 40.2/5.5 +/- 15.3 (systole/diastole) mmHg.hour/day and the mean hypobaric index, 12.2 +/- 22.5/9.0 +/- 24.0 mmHg.hour/day. The 50 untreated hypertensives showed a mean hyperbaric index of 281.8 +/- 197.0/156.0 +/- 126.1 mmHg.hour/day and a mean hypobaric index of 0.1 +/- 0.6/0.3 +/- 1.5 mmHg.hour/day. Comparison of the indexes before and after treatment with various antihypertensives showed that a decrease in the hyperbaric index without an increase in the hypobaric index was the most optimal reduction of blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

[Assessment of resting thallium-201 reinjection after stress-delayed Tl imaging (I): Comparison with 24-hour scan and regional wall motion]

Clinical value of resting reinjection of 1 mCi (37 MBq) of Tl after stress-delayed scan was assessed in comparison with 24 hr delayed scan and regional wall motion (RWM) in 37 patients with coronary artery disease. Of 101 segments with initial perfusion abnormality, concordant findings were observed after Tl reinjection in 67 segments (66%). But redistribution (RD) after Tl reinjection was observed in 19 of the 52 persistent defect (PD) segments (37%), and complete RD was observed 15 of the 43 segments (35%) where 3 hr scan showed incomplete RD. On the other hand, concordant findings were observed on 24 hr delayed scan in 11 of the 20 segments with perfusion abnormality (55%). RD on 24 hr delayed scan was observed in 5 of the 13 PD (38%), but it was not apparent in 3 of the 7 segments where 3 hr scan showed RD. Furthermore the segments which showed RD after Tl reinjection in PD segments tend to have less severe RWM abnormality than the sustained PD segments (RWM score: 1.65 +/- 1.17 vs. 2.29 +/- 1.05, p less than 0.05). These data indicate that Tl reinjection which permits assessment of RD with good quality images on the same day is considered as a valuable means for assessing myocardial viability.

[Usefulness of exercise Tl-201 myocardial scintigraphy: comparison with positron emission tomography]

To evaluate the usefulness of exercise Tl-201 myocardial scintigraphy, we performed positron emission tomography and conventional exercise Tl-201 emission computed tomography (ECT) in 33 patients with old anterior myocardial infarction (Q-MI: 24, non Q-MI: 9). N-13 ammonia was used as a blood flow tracer, and imaging was performed at rest and after multistage, symptom-limited ergometer exercise. After the administration of F-18 deoxyglucose (FDG) at rest in the fasting state, metabolic imagings were performed to evaluate regional exogenous glucose utilization. Tl-ECT showed fixed defects in 19 of the 33 patients, redistribution of the tracer in nine and no defects in five. All patients having partial or complete redistribution on Tl-ECT showed exercise-induced ischemia on PET with N-13 ammonia and an increased uptake of FDG in the hypoperfused region, suggesting the presence of ischemic but potentially salvageable tissues. In addition, PET with N-13 ammonia detected periinfarct ischemia in nine of the 19 with fixed defects on Tl-ECT, and increased uptakes of FDG were observed in eight of the 19. These results indicate that Tl-ECT may underestimate myocardial viability in clinically infarcted regions. Further studies are needed to determine whether restoring coronary flow improves wall motion in regions with fixed defects on Tl-ECT.

Quantitative analysis of regional wall motion by gated myocardial positron emission tomography: validation and comparison with left ventriculography

Electrocardiographically gated positron emission tomography (ECG-gated PET) with [13N] ammonia was used to assess regional myocardial wall motion of left ventricle (LV) based on a nongeometric method in nine healthy volunteers and 16 patients with coronary artery disease (CAD). Three transverse sections (upper, middle, and lower) with 16-mm intervals at end-diastole (ED) and end-systole (ES) were analyzed. The LV wall was divided into eight segments with every 30 degrees from septal wall to lateral wall. Based on circumferential profile analysis, the percent count increase [( ES count - ED count) divided ED count x 100) in each segment was analyzed as an index of regional wall motion. In the study of normal controls, the percent count increase was the lowest (32.9 +/- 7.2%) at septal wall of the lower slice and the highest (72.8 +/- 26.5%) at lateral wall of the upper slice (p less than 0.01). In five normal controls, the percent count increase was compared with the percent systolic wall thickening analyzed by magnetic resonance imaging, and a good correlation was observed (r = 0.84). In the study of patients with CAD, the percent count increase was compared with wall motion assessed by left ventriculography (LVG). The percent count increase significantly decreased as wall motion on LVG worsened. In addition, the value in normal controls tended to be higher than that in the segments with normal wall motion in patients with CAD. Thus, quantitative analysis of regional wall thickening was feasible by ECG-gated PET, which should be useful for combined analysis of regional function, perfusion and metabolism in patients with CAD.

[Assessment of myocardial viability by quantitative analysis of stress Tl-SPECT--comparison with FDG-PET]

Stress Tl-201 tomography (SPECT) is widely used for evaluating myocardial viability. To assess its value, redistribution (RD) on SPECT was compared with metabolic imaging using FDG. Thirty patients with coronary artery disease underwent stress-3 hour Tl-201 SPECT and PET using N-13 ammonia and FDG. RD was classified into 4 grading, including complete RD (CR), incomplete RD (IR), persistent defect (PD) and additional minimal RD (MR) defined as no definite RD on visual analysis but faint RD with Bull's eye quantitative analysis (QNT). All but one segment with CR or IR were viable regions (normal or ischemic regions) by PET. Of 74 segments without RD on visual analysis, 31 segments (42%) had RD by QNT (MR). All of them were viable regions by PET. Thus, QNT identified 31 segments (63%) of the metabolically viable segments which the visual Tl-201 analysis did not show RD and classified as myocardial scar. However, even such QNT cannot detect ischemic myocardium in 18 segments (42%) containing metabolic activity on PET. These data indicate that QNT of RD on Tl-201 SPECT is considered as a valuable means for assessing myocardial ischemia.

Silent myocardial ischemia in patients with myocardial infarction: evaluation with positron emission computed tomography

To evaluate myocardial blood flow and glucose utilization, N-13 ammonia and F-18 deoxyglucose positron emission tomography were performed in 33 patients with myocardial infarction. The N-13 ammonia study was performed at rest and during supine exercise, and the F-18 deoxyglucose was done at rest after greater than or equal to 5 hours of fasting. Based on angina, exercise-induced hypoperfusion, and deoxyglucose uptake, 3 groups of patients were classified; 10 patients in group I (neither angina nor exercise induced hypoperfusion), 8 patients in group II (painless exercise-induced hypoperfusion) and 15 patients in group III (anginal patients with/without exercise-induced hypoperfusion). The F-18 deoxyglucose positron study demonstrated accumulation of deoxyglucose in 6 patients in group I, 7 in group II, and 14 in group III. Thus, our results indicated that a significant number of patients with antecedent myocardial infarction had exercise-induced hypoperfusion and/or altered glucose metabolism without accompanying anginal pain.

[A double-blind comparative study of intracoronary administration of GE-0943 and urokinase: multicenter study]

Coronary thrombolysis with plasminogen proactivator, GE-0943, was undertaken in patients with acute myocardial infarction and compared with urokinase. Fifty patients were given 6000 units of GE-0943 intracoronary and the totally occluded infarct-related arteries were recanalized in 92.0%. Fifty-four patients who were given 3000 units of GE-0943 intracoronary demonstrated a recanalization rate of 68.2%, while intracoronary administration of urokinase in 54 patients showed a recanalization rate of 70.4%. There was only one patient with hemorrhagic complication among GE-0943 3000-units group, none among GE-0943 6000-units group, and 5 among urokinase group. Thus, intracoronary administration of GE-0943 is very effective and safe with a dose up to 6000 units.

Effects of intravenous administration of nicorandil on cardiovascular hemodynamics and left ventricular function

The effects of the intravenous administration of the antianginal drug, nicorandil, 50 micrograms/kg administered over 2 minutes, were investigated during pacing-induced ischemia in 8 patients with coronary artery disease. Hemodynamic parameters were measured and single-plane left ventriculograms were obtained in control and postpacing periods both before and after pretreatment with nicorandil. Regional wall motion of the left ventricle was assessed by measuring shortening of the radial axes originating from the center of gravity of the end-diastolic silhouette. Heart rate, left ventricular (LV) systolic pressure and end-diastolic volume index did not change in the immediate postpacing period with or without medication. LV end-diastolic pressure decreased with nicorandil, from 22.0 +/- 3.4 to 17.0 +/- 2.3 mm Hg (mean +/- standard error of the mean) (p less than 0.05), and LV systolic volume index, from 39.6 +/- 8.0 to 30.4 +/- 6.8 ml/m2 (p less than 0.05). Ejection fraction increased from 55.2 +/- 5.0 to 64.3 +/- 3.8% (p less than 0.05). Stroke index and cardiac index (calculated from heart rate and stroke index) did not change significantly. Rapid right ventricular pacing increased the extent and degree of dyskinesia of the left ventricle, but premedication with nicorandil improved the wall motion. Thus, nicorandil has salutary effects on ventricular contractile and hemodynamic responses to transient ischemia induced by pacing stress.