Tumor blood flow and systemic shunting in patients receiving intraarterial chemotherapy for head and neck cancer.

Radionuclide techniques have been used to estimate the systemic shunt and to quantitate blood flow to the tumor and a reference normal tissue in nine patients undergoing intraarterial chemotherapy for head and neck cancer. The systemic shunt was calculated as the percentage of pulmonary trapping of intraarterially injected 99mTc-labeled macroaggregated albumin. The mean systemic shunt in the 12 separate arteries studied was 23 +/- 13% (SE) (range 8-43%). Quantitative blood flow was determined from the slope of the washout curve of intraarterially injected 133Xe. The mean tumor blood flow was 13.6 +/- 6.7 ml/100 g/min, while the mean blood flow to the scalp was 4.2 +/- 2.1 ml/100 g/min providing a mean tumor/normal tissue ratio of 3.9 +/- 2.7. An estimate of blood flow distribution was obtained by calculating the ratio of counts/pixel in the tumor mass versus the remainder of the head as determined by single photon emission computed tomography following an intraarterial injection of 99mTc-labeled macroaggregated albumin. The mean ratio of tumor to normal tissue perfusion by this technique was 5.6 +/- 3.7. These techniques have allowed noninvasive determination of the blood flow parameters associated with intraarterial chemotherapy. At least part of the therapeutic advantage of regional chemotherapy in patients with head and neck cancer is due to a tumor/normal tissue blood flow ratio that favors drug delivery to the tumor contained within the infused volume.

Effects of hepatic arterial yttrium-90 microsphere administration alone and combined with regional bromodeoxyuridine infusion in dogs.

Brachytherapy by embolization with radiotherapeutic microspheres following intraarterial infusion of a radiosensitizer represents an attempt to combine several selective modalities into a more potent, focused attack on regionally confined tumors. In pursuit of this goal, we examined the ability of foxhounds with surgically implanted hepatic arterial (HA) delivery systems to tolerate a clinically relevant dosage of HA yttrium-90 (Y-90) by microsphere administration either alone or preceded by a 28-day constant HA infusion of either 5-bromo-2'-deoxyuridine (BUDR) or a control solution. Five dogs received BUDR (10 mg/kg/day) and five a control buffer infusion for 28 days immediately prior to the administration of Y-90-coated 15 micron resin microspheres (equivalent of 5000 rads to the entire liver) to each dog on day 31. In all animals, blood counts, bilirubin, amylase, appetite, weight, and behavior remained unchanged. Dogs receiving the microspheres after buffer infusion alone exhibited no hepatic enzyme alanine aminotransferase or alkaline phosphatase elevation. Alanine aminotransferase and alkaline phosphatase levels both rose during the third week of BUDR infusion, and while subsequent microsphere administration further increased enzyme levels, these levels had largely normalized by necropsy on day 82. At necropsy, the type and degree of hepatic toxicity among the animals receiving radioactive microspheres was comparable to that previously described in patients receiving external beam hepatic irradiation at conventional doses (2000-3000 rads). Also noted was a radiation-induced cholecystitis (due in large part to the gallbladder's total reliance on the hepatic artery for blood supply). One resin microsphere dog exhibited a small quantity of microspheres in the lungs causing focal radiation-induced granulomas suggesting the need to assess shunting of microspheres through the liver in clinical studies. Thus, HA Y-90 microspheres with BUDR can produce acceptable, nonlethal, and tolerable toxicities in this dog model suggesting that clinical studies of this combination are not likely to be contraindicated by synergistic toxicity. Although HA BUDR did not contribute significantly to the toxicity of the Y-90 microspheres, HA BUDR by itself administered uninterrupted for 4 weeks may, like HA FUDR (clinically), cause chemical hepatitis/cholangitis. The unexpected fragmentation of the resin spheres (albeit without myelosuppression) has led us to begin studies with a recently developed nondisruptible glass microsphere (ThereSphere) in which the Y-90 is part of the glass matrix and cannot leach.(ABSTRACT TRUNCATED AT 400 WORDS)

Localization and imaging with radioiodine-labeled monoclonal antibodies in a xenogeneic tumor model for human B-cell lymphoma.

Two MoAbs directed towards human B-cell malignancies have been studied in a preclinical animal model to evaluate their potential for in vivo imaging and therapy of B-cell lymphomas. Anti-B1 reacts with virtually all immunoglobulin-bearing malignancies and non-T acute lymphoblastic leukemia. Anti-J5 reacts with the common acute lymphoblastic leukemia antigen found on non-T acute lymphoblastic leukemia and follicular lymphomas. Anti-T1 which recognizes the CD5 antigen on most T-cell leukemias and lymphomas was used as a control antibody. These monoclonal antibodies were radiolabeled with 125I or 131I by the ICl method. Namalwa (B-cell) and MOLT-4 (T-cell) tumors were grown s.c. in irradiated nude mice. The highest tissue concentration of 125I-labeled anti-J5 in Namalwa-bearing mice was in blood and tumor. The tumor/blood ratio ranged from 0.7-1.2, with the highest ratio 4 days after injection. Pharmacokinetic analysis indicated that the t1/2 beta of anti-J5 from blood and other tissues ranged from 40-50 h, while the t1/2 beta for tumor averaged 65 h. The area under the curve of tumor was 2- to 5-fold higher than the area under the curve of liver, kidney, skin, and muscle. The peak tissue levels of 125I-labeled anti-B1 in Namalwa-bearing mice were again in blood and tumor and 6 days following injection more than 5-fold greater activity was found in tumor compared to normal tissues other than blood. The tumor/blood ratio was 1.2 and 0.7 at 4 and 6 days after injection. 125I-labeled anti-B1 showed minimal uptake in antigen-negative MOLT-4 tumors and 125I-labeled anti-T1 showed little uptake in Namalwa tumors. Scintigraphic images were obtained following the injection of 131I-labeled anti-J5 and anti-B1 in nude mice bearing Namalwa tumors. These results indicate that radiolabeled anti-J5 and anti-B1 show promise as diagnostic and possibly therapeutic agents for human B-cell lymphoma, although there may be a limitation to clinical utility due to cross-reactivity with some normal cells.

Radionuclide assessment of left ventricular diastolic filling in diabetes mellitus with and without cardiac autonomic neuropathy.

Indexes of left ventricular diastolic filling were measured by radionuclide ventriculography in 28 patients with insulin-dependent diabetes mellitus without evidence of ischemic heart disease. Six patients (21%) had abnormal diastolic filling and differed from diabetic patients with normal filling in their greater severity of cardiac autonomic neuropathy, assessed by noninvasive means, and their lower plasma norepinephrine levels in the supine (131.1 +/- 24.7 versus 356.2 +/- 58.4 pg/ml, p less than 0.01) and upright (224.9 +/- 47.8 versus 673.3 +/- 122.3 pg/ml, p less than 0.005) positions. The diabetic patients determined as having cardiac autonomic neuropathy (n = 15) had depressed left ventricular diastolic filling compared with subjects free of autonomic neuropathy, whether measured as the time to peak filling rate (154.2 +/- 12.0 versus 119.1 +/- 10.6 ms, p less than 0.05) or the time to peak filling rate normalized to the cardiac cycle length (24.3 +/- 2.2 versus 16.2 +/- 1.5%, p less than 0.01). Of the various tests of autonomic nervous system function, the strongest correlate of impaired diastolic filling was orthostasis, measured as the decrease in systolic blood pressure with standing (r = 0.584, p less than 0.001). Thus, in patients with diabetes mellitus, alterations in sympathetic nervous system activity are associated with abnormalities of left ventricular diastolic filling.

Prevention of subsequent exercise-induced periinfarct ischemia by emergency coronary angioplasty in acute myocardial infarction: comparison with intracoronary streptokinase.

To compare the efficacy of emergency percutaneous transluminal coronary angioplasty and intracoronary streptokinase in preventing exercise-induced periinfarct ischemia, 28 patients presenting within 12 hours of the onset of symptoms of acute myocardial infarction were prospectively randomized. Of these, 14 patients were treated with emergency angioplasty and 14 patients received intracoronary streptokinase. Recatheterization and submaximal exercise thallium-201 single photon emission computed tomography were performed before hospital discharge. Periinfarct ischemia was defined as a reversible thallium defect adjacent to a fixed defect assessed qualitatively. Successful reperfusion was achieved in 86% of patients treated with emergency angioplasty and 86% of patients treated with intracoronary streptokinase (p = NS). Residual stenosis of the infarct-related coronary artery shown at predischarge angiography was 43.8 +/- 31.4% for the angioplasty group and 75.0 +/- 15.6% for the streptokinase group (p less than 0.05). Of the angioplasty group, 9% developed exercise-induced periinfarct ischemia compared with 60% of the streptokinase group (p less than 0.05). Thus, patients with acute myocardial infarction treated with emergency angioplasty had significantly less severe residual coronary stenosis and exercise-induced periinfarct ischemia than did those treated with intracoronary streptokinase. These results suggest further application of coronary angioplasty in the management of acute myocardial infarction.

Decreased exercise heart rate and blood pressure response in diabetic subjects with cardiac autonomic neuropathy.

Abnormal hemodynamic responses to exercise have been observed in diabetic subjects, but the pathogenesis and significance remain uncertain. We used maximal treadmill exercise to study 32 subjects with long-term insulin-dependent diabetes without clinical evidence of cardiac disease. Two of the 32 had occult ischemic heart disease revealed by stress electrocardiography and myocardial-perfusion scintigraphy and were excluded from subsequent analysis. In the remaining 30 subjects, we compared the responses to exercise of the 17 subjects with cardiac autonomic neuropathy diagnosed by noninvasive maneuvers (group 1) with the 13 without (group 2). At rest, the pressure-rate product (PRP) was higher in group 1 (114.0 +/- 5.7 vs. 95.9 +/- 5.3, P less than .05). With maximal exercise the increase in heart rate (44.6 +/- 4.8 vs. 79.0 +/- 5.4 beats/min, P less than .001), systolic blood pressure (36.8 +/- 5.9 vs. 55.0 +/- 5.8 mmHg, P = .02), and the PRP (102.0 +/- 7.3 vs. 182.0 +/- 8.2, P less than .001) were all lower in group 1 than in group 2, despite similar total treadmill times (631 +/- 47 vs. 587 +/- 40 s, P greater than .1). At each stage of exercise, the increase in heart rate and systolic blood pressure was lower in group 1 patients. The severity of cardiac autonomic neuropathy correlated inversely with the maximal increase in heart rate (r = -.68, P less than .001) and the PRP (r = -.58, P less than .005). Age, duration of diabetes, and the presence and severity of microvascular disease did not correlate with any of the hemodynamic parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormal cardiac function in diabetic patients with autonomic neuropathy in the absence of ischemic heart disease.

To determine if cardiac autonomic neuropathy (CAN) contributes to diabetic cardiomyopathy, left ventricular function was assessed by resting and exercise radionuclide ventriculography (RVG) in 30 patients with long-standing insulin-dependent diabetes mellitus who had no clinical, electrocardiographic, or tomographic thallium scan evidence of heart disease. In 11 of 30 patients (37%), RVG revealed abnormal left ventricular performance. CAN was found in 91% of these patients. RVG was abnormal in 59% of patients with CAN and in only 8% of patients without CAN (P less than 0.005). There were significant reductions in mean (+/- SE) ejection fractions (EF) in patients with CAN at rest (62.8 +/- 2.2% vs. 75.2 +/- 2.5%; P less than 0.001) and with maximal exercise (65.8 +/- 2.6% vs. 80.9 +/- 2.3%; P less than 0.001) compared to patients without CAN. There was an inverse correlation between the autonomic function score and both resting EF (r = -0.53; P less than 0.002) and exercise EF (r = -0.55; P less than 0.002). Systolic function did not correlate with age, sex, duration or control of diabetes, microvascular complications, or plasma norepinephrine levels. Thus, approximately one third of our study population had evidence for depressed left ventricular function in the absence of ischemic heart disease, and the cardiac dysfunction was related to the severity of CAN. CAN may be a contributor to cardiac dysfunction in diabetes mellitus.

Effects of gating modes on the analysis of left ventricular function in the presence of heart rate variation.

Variations in cardiac cycle length during ECG-gated radionuclide ventriculography cause errors in measurement of left ventricular (LV) diastolic function. We used a computer model to investigate the relative accuracy of forward gating (FG), backward gating (BG), and three methods of combined forward-backward gating (FBG). LV time-activity curves (TAC) were simulated with total cycle lengths randomly varied (1 s.d. = +/- 10%). To match the known differential effects of cycle-length variation on various parts of the cardiac cycle, 90% this variation was placed in diastasis and 10% in the rapid filling phase. Three hundred cycles of TACs were summed to form one "study". A total of 25 studies were performed and systolic and diastolic parameters were determined for each. These were compared to those of the mean length TAC. With a 20% cycle-length acceptance window, error in peak filling rate by FG was 0.7% root-mean-squared (RMS) compared to 18.5% RMS by BG. With a 5% window, RMS error by FG was 0.2% and 2.4% RMS by BG. Combined FBG algorithms gave intermediate results. We conclude that the simplest and most accurate method of analysis is to acquire forward gated TACs with appropriate cycle-length windows.

Scintigraphic demonstration of accessory hepatic duct leak following liver transplantation.

Few noninvasive methods are available to diagnose complications following liver transplantation. Hepatobiliary scintigraphy can differentiate rejection from primary biliary complications such as obstruction or extravasation in patients with nonspecific clinical findings such as fever and rising liver function studies. In the following case report, an unexpected biliary leak from a recipient accessory hepatic duct was demonstrated by [99mTc] DISIDA scintigraphy following liver transplantation.

Hepatocyte versus biliary disease: a distinction by deconvolutional analysis of technetium-99m IDA time-activity curves.

A combination of quantitative hepatobiliary imaging techniques was developed to study normal control subjects and patients with 3 categories of hepatobiliary disease: 1) alcoholic cirrhosis; 2) sclerosing cholangitis; and 3) isolated common bile duct obstruction. Scintigraphic images were supplemented by quantitative measurement of hepatic extraction fraction by deconvolutional analysis and liver excretion T 1/2 by a nonlinear least squares method. In diseases confined primarily to the biliary tract (isolated common bile duct obstruction and sclerosing cholangitis), the mean hepatic extraction fraction as measured by deconvolutional analysis was not different from that in normal controls. In severe alcoholic cirrhosis, considered primarily a hepatocyte disease, the hepatic extraction fraction was markedly reduced. The T 1/2 excretion, compared to normal subjects, was prolonged in all three liver disease categories. We conclude that these quantitative parameters were able to detect hepatobiliary disease and to separate severe hepatocyte disease from biliary tract disease.

Recurrent medullary carcinoma of the thyroid demonstrated by thallium-201 scintigraphy.

Thallium-201 scintigraphy has been used in the evaluation of thyroid neoplasms, but uptake in recurrent or persistent medullary thyroid cancer has not been reported. We present two cases where focal 201TI activity localized superior mediastinal recurrences which were subsequently resected. Postoperative 201TI scans in both cases showed elimination of the focal uptake seen before surgery, as well as return of previously elevated serum calcitonin levels to normal. Scanning with 201TI may be useful in the preoperative localization of recurrent medullary thyroid cancer.

Effects of alterations in systolic pressure on radionuclide measurements of left ventricular filling dynamics.

To determine the effects of steady-state left ventricular systolic pressure alterations on radionuclide measures of left ventricular filling dynamics, we studied 15 normal patients and 17 patients with nonischemic heart disease. Micromanometer left ventricular pressures and computer assisted forward gated radionuclide angiograms were acquired simultaneously. Right atrial pacing maintained heart rates constant during the baseline condition and methoxamine and nitroprusside infusions. Diastolic filling dynamics, peak filling rate and time to peak filling rate were calculated using a three harmonic Fourier analysis of the left ventricular time-activity curves. Left ventricular systolic pressure increased to 165 +/- 25 mmHg with methoxamine (p < 0.001) and decreased to 106 +/- 18 mmHg with nitroprusside (p < 0.001) from a baseline value of 133 +/- 16 mmHg. Radionuclide left ventricular filling dynamics did not change significantly. Thus, we conclude that radionuclide measurements of left ventricular filling dynamics are not affected by modest, steady-state alterations in left ventricular systolic pressure and can therefore be useful for the assessment of left ventricular diastolic function during interventions which may also affect left ventricular systolic pressure.

Quantitative myocardial SPECT for infarct sizing: feasibility of a multicenter trial evaluated using a cardiac phantom.

UNLABELLED: This study determined the feasibility of performing a multicenter trial using quantitative SPECT myocardial perfusion imaging in patients with acute myocardial infarction. The feasibility was assessed by a cardiac phantom. METHODS: Twenty-two gamma camera systems in 19 laboratories were evaluated. Each laboratory performed nine studies on the cardiac phantom and performed quality control tests of system uniformity, collimator quality and gantry alignment on their gamma camera system. Defects simulating "hypoperfused" myocardium of differing amounts were placed in the myocardium for eight of the nine studies. Measured defect size was compared to true defect size. RESULTS: A total of 198 studies from 22 systems were analyzed. Three studies were technically inadequate. For all 22 systems, the average correlation coefficient between true and measured defect size was 0.992 +/- 0.009, with a range from 1.00 to 0.97. Three systems were rejected due to slopes of the regression line outside the limits 1.00 +/- 0.10 and mean errors > 5% in estimating defect size. The remaining systems had a correlation coefficient of 0.995 + 0.008 with an average slope of 1.00 +/- 0.04 and an intercept of 0.11% +/- 1.57%. The mean error in estimating defect size was 2.08% +/- 0.69%. CONCLUSION: The small interlaboratory variation and the close correlation with true defect size observed in a cardiac phantom indicate the feasibility of quantitative myocardial SPECT as a useful tool in multicenter trials evaluating therapy in acute myocardial infarction. Preliminary objective testing is required, however, to identify systems with technical deficiencies.

Dynamic arrhythmia filtration for gated blood-pool imaging: validation against list mode technique.

Normal resting heart rate variations distort the diastolic portions of left ventricular time-activity curves, altering calculated measures of diastolic function such as peak filling rate. Diastolic filling parameters obtained by two methods of arrhythmia removal--list-mode acquisition and a new approach, dynamic arrhythmia filtration (DAF)--were compared. In DAF, data are evaluated for cycle length in real time and accepted or rejected immediately according to preset, operator-determined cycle-length criteria, eliminating the need for postprocessing of data and for large mass data storage. We prospectively determined EF, time to end-systole, peak filling rate, and time to peak filling on gated blood-pool studies of 25 patients. Identical camera and ECG data were sent simultaneously to two computers and analyzed using list mode and DAF, with an R-R interval of 5-6% of mean heart rate. Excellent correlation between list mode and DAF was seen in peak filling rate (r = 0.94), EF (r = 0.99), and time to end-systole (r = 0.97). Lesser correlation seen in time to peak filling (r = 0.65) may be due to inherent problems in measuring this parameter reliably, possibly lessening this parameter's clinical usefulness. DAF is less time consuming and less technically demanding than list mode, and provides results which correlate closely to those obtained by list mode.

Ratio of hepatic arterial-to-portal venous blood flow--validation of radionuclide techniques in an animal model.

The ratio of hepatic arterial-to-portal venous blood flow can be determined from the analysis of a first-pass bolus through the liver by a number of techniques. This study examines the validity of four radiotracer techniques in an animal model. Thirty-four flow studies (3 mCi 99mTc-DTPA/study) were performed in seven anesthetized pigs. Images were acquired for 200 sec and time-activity curves were generated from lung, liver and kidney ROIs. These curves were analyzed using a slope-based (HPI), a height-based (mHAR) and two deconvolution-based methods employing exponential or gamma variate fits. There was an excellent correlation (r greater than 0.9) between results obtained with flow probes and the radiotracer techniques, with the exception of the HPI technique (r = 0.75). The mHAR and deconvolution techniques were inaccurate at very low and high arterial flows, due respectively to noise limitations and hemodynamic instability in the animal. Nevertheless, these techniques appear to be the most promising for routine clinical use.

Modified PIOPED criteria used in clinical practice.

UNLABELLED: To assess the use of modified PIOPED scintigraphic criteria for lung scan (V/Q) interpretation to detect pulmonary embolism (PE), we prospectively applied these criteria in suspected PE patients referred for V/Q from 9/1/92 to 2/7/94. PIOPED criteria were modified by placing a moderate segmental perfusion mismatch in the intermediate instead of low probability of PE category and using the "stripe sign." METHODS: Patients were studied by six-view V/Q imaging using 74 MBq (2 mCi) 99mTc-MAA followed by 148-370 MBq (4-10 mCi) 99mTc-DTPA aerosol, contrast pulmonary selective angiography and Doppler sonography with leg compression as needed. Patients underwent follow-up (mean 13.9 mo) to detect subsequent thromboembolic events. In this study group, 1000 patients were studied by V/Q followed by angiography in 133 patients. RESULTS: The distribution of V/Q-assigned PE probabilities was: high probability 5.7%, intermediate 17.4%, low 41.4% and normal 35.5%. Group A patients (133) underwent angiography, which resulted in the determination of a 27.1% PE prevalence. Group B patients (867) did not have angiograms; the clinical prevalence of PE was 7.5%. In the total study population, the positive predictive value of a high probability V/Q study for PE (10.1% prevalence) was 98.2%, intermediate probability V/Q study for PE was 24.1% and a low probability study for PE was only 0.5%. CONCLUSION: Modified PIOPED V/Q interpretation criteria afford better angioproven PE discrimination between intermediate (31.8% PE prevalence) and low (5.5% PE prevalence) probability V/Q results than reported for PIOPED intermediate (32.6% PE prevalence) and low (16.3% PE prevalence) probability V/Q interpretation criteria.

Ventilation-perfusion scintigraphy in the PIOPED study. Part I. Data collection and tabulation.

The Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) study of more than 700 patients is the largest existing study of the accuracy of lung scintigraphy in the diagnosis of acute pulmonary embolism. Perfusion scans were obtained in all patients and ventilation scans in almost all, using standardized techniques. Chest radiographs were obtained in all patients within 12 hr of the lung scan. Most patients underwent pulmonary arteriography. The images were interpreted according to a set of interpretive criteria which remained constant throughout the trial. A standardized, detailed description of each image set was derived by consensus of teams of two readers blinded to clinical and arteriographic findings. This communication reports the methods used to describe and categorize the ventilation-perfusion scintigrams obtained in patients who were enrolled in the PIOPED study. Scintigraphic technique is reviewed briefly, probability assessment is described and the scan description is reviewed in detail. The form used to describe the findings on ventilation-perfusion scans is reproduced. Use of this standardized description permits retrospective evaluation of the PIOPED interpretive criteria. In addition, it represents a rigorous approach to scan analysis which could facilitate application of formal interpretive schemes and enhance the reproducibility of lung scan interpretations in the clinical setting.

Ventilation-perfusion scintigraphy in the PIOPED study. Part II. Evaluation of the scintigraphic criteria and interpretations.

This article presents an evaluation of the criteria used for categorical interpretation of the ventilation-perfusion (V/Q) scans performed in the PIOPED study. In addition, the correlation of percent probability estimates with the actual frequency of pulmonary embolism (PE) is presented. Cases which met the PIOPED criteria for various diagnostic categories were selected by computerized search of the detailed scan descriptions that had been done as part of the study. The process by which the scans were described was detailed in Part I of this report. Most of the criteria appropriately categorized V/Q scans which satisfied them. However, we recommend that three criteria should be reconsidered: 1. A single moderate perfusion defect is appropriately categorized as intermediate, rather than as low probability. 2. Extensive matched V/Q abnormalities are appropriate for low probability, provided that the chest radiograph is clear. On the other hand, single-matched defects may be better categorized as intermediate probability. Although due to the small number of cases with this finding, no definite, statistically founded recommendation can be made. 3. Two segmental mismatches may not be the optimum threshold for high probability, and in some cases should be considered for intermediate probability. However, due to the small number of cases with this finding, no definite, statistically founded recommendation can be made. We suggest that the revised criteria resulting from these adjustments should now be used for the interpretation of V/Q scans.

PET perfusion and vasodilator function after angioplasty for acute myocardial infarction.

UNLABELLED: The aims of this study were to validate invasive coronary Doppler flows against noninvasive PET assessments of myocardial perfusion and to examine the timing and degree of regional coronary vasodilator reserve recovery in patients who are successfully reperfused with primary angioplasty (PTCA) for acute myocardial infarction. METHODS: PTCA was performed in 21 consecutive patients with acute myocardial infarction; the final diameter stenosis was 25% +/- 7%. After restoration of TIMI Grade 3 flow, all patients underwent quantitative coronary angiography and distal Doppler coronary blood flow studies (basal and after adenosine-induced hyperemia) in the infarct and noninfarct vessels. Regional myocardial perfusion and vasodilator function were quantitated after intravenous adenosine infusion PET in all patients at 26 +/- 9 hr after acute PTCA. These were repeated in 17 patients 9 +/- 3 days later. RESULTS: Post-PTCA resting coronary flow was 35 +/- 15 ml/min in the infarct-related vessels and 50 +/- 24 ml/min during peak hyperemia (p < 0.05). Coronary flow reserve (CFR) was 1.48 +/- 0.34 and 2.08 +/- 0.62 in the infarct and noninfarct vessels, respectively (p < 0.001). Early (< 36 hr) PET myocardial perfusion reserves (MPR) in the infarct and noninfarct regions were 1.59 +/- 0.33 and 2.03 +/- 0.62 (p < 0.01). Doppler CFR and PET MPR were correlated in the infarct (r = 0.61, p < 0.01) and noninfarct (r = 0.77, p < 0.0001) regions. Follow-up PET studies demonstrated improved MPR in both infarct and noninfarct regions (1.93 +/- 0.52 versus 2.54 +/- 0.97, p < 0.01). The improvement in coronary vasodilator function from the time of acute PTCA to follow-up PET in the infarct region was significant (p = 0.005). CONCLUSION: After successful mechanical revascularization by PTCA after acute myocardial infarction, intracoronary Doppler blood flows and noninvasive PET regional myocardial perfusion are correlated within the wide range of reperfusion blood flows observed in patients with contrast angiographic TIMI Grade 3 flow. Serial PET studies demonstrated a trend towards continued improvement in the vasodilator response in infarct-related myocardial regions after the restoration of blood flow by PTCA. PET offers the potential for accurate noninvasive serial assessment of reperfusion blood flow after primary angioplasty for acute myocardial infarction.

Prognostic significance of exercise-induced left ventricular dysfunction in chronic aortic regurgitation.

Twenty-three patients with hemodynamically significant aortic regurgitation (AR) underwent gated equilibrium radionuclide angiography to assess rest and exercise left ventricular ejection fraction (LVEF) before and after aortic valve replacement. Preoperatively, LVEF decreased from 54 +/- 3% at rest to 45 +/- 3% during exercise (p less than 0.001). Two patients died at operation. Postoperatively, after 5.7 +/- 1.6 months, LVEF was 62 +/- 5% at rest and 60 +/- 4% during exercise (difference not significant). Exercise LVEF improved significantly postoperatively (p less than 0.01). The patients were followed for a mean of 30 months (range 1 to 56), after valve replacement and during this period, 13 patients were in functional class I, 5 patients were in class II and 2 patients were in class III. One late death occurred and was unrelated to myocardial failure. Thus, in most patients with AR, exercise LVEF improves after aortic valve replacement. A preoperative decrease in LVEF during exercise in patients with significant AR does not predict a poor postoperative outcome.