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Background: Lymphoseek is a radiopharmaceutical designed for sentinel lymph node (SLN) mapping. The purpose of this study was to compare Lymphoseek colon and gastric pharmacokinetics with filtered [(99m)Tc]sulfur colloid (fTcSC)., Methods: Eight anesthetized pigs received an endoscopic injection of Lymphoseek or fTcSC in the stomach and colon. Scintigraphy was obtained of both administration sites at 15-minute intervals up to 3 hours after injection, after which all SLNs were identified by a handheld gamma probe through a laparotomy incision. Isosulfan blue was administered at the injection site 5 minutes before SLN mapping. The percentage of injected dose (%ID) was measured for all harvested nodes, and the clearance half-life (T(c)) was calculated for all injection sites., Results: The mean Lymphoseek clearance for colon (T(c), 2.56 +/- 1.04 hours) and gastric (T(c), 3.83 +/- 1.18 hours) injection sites was statistically faster (P =.030) compared with fTcSC (colon T(c), 14.98 +/- 3.41 hours; stomach T(c), 14.52 +/- 4.08 hours). After 3 hours, Lymphoseek exhibited a mean SLN %ID of 1.32% +/- 1.71% in the colon and 2.04% +/- 2.12% in the stomach; this was not statistically different from fTcSC (colon,.63% +/-.39%; stomach, 2.35% +/- 2.90%). SLN uptake of Lymphoseek was significantly different from second-echelon node %ID for the colon (P =.011) and gastric (P =.029) injection sites. All SLNs exceeded 10 times background, and there was no discordance between isosulfan blue and Lymphoseek or fTcSC., Conclusions: Three hours after colon stomach administration, Lymphoseek demonstrated rapid injection site clearance, detectable SLN uptake, and low second-echelon node uptake.

Purpose: To study the relationship of regional hypoperfusion and areas of decreased lung attenuation on computed tomographic (CT) scans of patients with chronic pulmonary thromboembolism., Materials and Methods: Preoperative CT scans of five patients (four men and one woman, aged 29-72 years) with chronic pulmonary thromboembolism were reviewed and compared with axial single photon emission CT (SPECT) perfusion scans obtained at similar levels. Regions of varying attenuation and perfusion were scored on a three-point scale., Results: In the five patients, 198 regions were identified. Of 176 abnormal regions at SPECT, 133 were abnormal at CT (sensitivity, 75.6%). Eleven of 22 regions interpreted as normal at SPECT were judged to have normal attenuation at CT (specificity, 50%). The overall accuracy of CT for detecting areas of hypoperfusion was 72.7% (P = .011)., Conclusion: A mosaic pattern of lung attenuation at CT is a sign of variable regional perfusion and may suggest chronic pulmonary thromboembolism as a cause for pulmonary hypertension.

In this preliminary study, four patients suspected of having pulmonary emboli underwent ventilation imaging after inhaling approximately 1 mCi (37 MBq) of Tc-99m Pertechnegas (micro aerosol carbon particles labeled with Tc-99m) in five breaths or less. Planar images in multiple projections were recorded for preset counts. A final posterior image was acquired to evaluate residual lung background activity. Immediately following ventilation imaging, perfusion imaging in the identical projections was performed using 4 mCi (148 MBq) of Tc-99m MAA. Two of the four patients demonstrated matched uniform ventilation and perfusion and two showed segmental ventilation-perfusion "mismatched" defects consistent with pulmonary emboli. In each case, residual Pertechnegas background lung activity (count rate) at the end of the last ventilation image was less than 10% of the initial Tc-99m MAA counts (count rate). The advantages of Pertechnegas, in comparison to aerosolized DTPA, include: less residual ventilation image activity superimposed on the MAA perfusion images, reduced demand for patient cooperation due to fewer required breaths (five or less), and lack of deposition of activity in the central airways. The authors conclude that Pertechnegas has properties that make it ideally suited for routine lung ventilation imaging.

This study reports on the frequency and clinical significance of false-positive thallium studies in the interventricular septum in patients with left bundle branch block. In a 3-year period, 93 studies were performed on patients with complete left bundle branch block and sinus rhythm. Of these, 29 had a reversible septal defect; 17 are scored false-positive although only six had angiographic proof of normal left anterior descending coronary arteries. We conclude that thallium scintigraphy is indicated in patients with left bundle branch block, but caution is justified when reversible ischemia is demonstrated scintigraphically.

A program was developed to extract from brain SPECT data global as well as regional concentrations of a radiopharmaceutical while allowing for improved subjective evaluation of its distribution. This program was used to process the data obtained from 17 normal subjects, 20 min, 2 hr, and 4 hr after the injection of iodine-labeled iodoamphetamines. The mean absolute cortical uptake at these three time periods was 0.921 (+/- 0.185), 0.803 (+/- 0.107), and 0.748 (+/- 0.103) in arbitrary units (+/- s.d.), respectively. The regional distribution of the tracer became more uniform with time due to an uneven washout rate. The cerebellum was noted to have a very high variability in its uptake and a high washout rate, making it unsuitable as an internal standard for relative quantification. Finally, a repeat study was performed on 10 subjects. No significant difference could be demonstrated in the mean uptake of the group at 2 and 4 hr, however the difference observed in the 20 min uptake values was significant at the p = 0.05 level.

A new Tc-99m labeled carbon particle aerosol ("Technegas") has been developed for lung ventilation scanning. This is the first reported clinical study of this agent in the United States. A total of 23 subjects were studied. Thirteen had comparative Xe-133 studies, and in seven patients pulmonary angiograms were available. The Technegas study agreed closely with the Xe-133 results in 10 out of 13 patients, while the pulmonary angiogram confirmed the Technegas and perfusion scan findings in seven out of seven cases. The Technegas scan was easily performed and well tolerated by all patients. If further clinical trials confirm these preliminary findings, Technegas may become the preferred agent for lung ventilation scanning.

Using equilibrium radionuclide angiography, we evaluated the ejection time (ET), peak ejection rate (PER), and time to peak ejection rate (TTp) at test and during supine bicycle exercise in 39 subjects, divided into three groups: group 1 = 13 normal subjects; group 2 = 10 patients with a previous infarction (MI); and group 3 = 16 patients with coronary disease without a previous MI. Normal subjects had greater ejection fractions and PERs than the other two groups at rest or peak exercise (p less than 0.05). PER was no more useful than ejection fraction in identifying cardiac dysfunction at either rest or exercise. The time of its occurrence varied with the group studied, and was slightly but significantly later in systole in groups 2 and 3 when compared to normals (p less than 0.05), though substantial overlap between groups occurred. During exercise, absolute ET shortened in all groups, but actually increased as a function of the R-R interval. The time to peak ejection rate (normalized for the R-R interval) was greater in the noninfarct group (group 3) patients (p less than 0.05) when compared to the group 1 or group 2 individuals at peak exercise. In conclusion, equilibrium radionuclide angiography is a useful technique for the quantification and characterization of events during systole, and is capable of providing information on the timing of events during ejection. Tardokinesis, or the delay of ventricular ejection, is not seen in the response of global indices of left ventricular function to exercise stress. While global early systolic indexes may not detect regional dyssynchrony, their timing during stress may occasionally aid in discerning the presence of cardiac dysfunction.

The prevalence of abnormal pulmonary perfusion (Q) scans in persons without cardiopulmonary disease could condition the usefulness of the Q scan in the evaluation of patients in whom pulmonary embolism is suspected. In a recent study, we found that Q scan defects, particularly lobar or segmental defects, are rarely present in normal young nonsmokers. To determine if normal smokers of the same age group have a higher prevalence of Q defects, we performed 6 view Q scans in 40 subjects 18 to 29 yr of age who had no known active cardiopulmonary disease. Each subject had undergone a history, physical examination, electrocardiogram, spirometry, and posteroanterior chest roentgenogram prior to scanning. All Q scans were interpreted blindly and independently by 2 experienced readers. None of the 40 subjects was found to have an abnormal Q scan defined as the presence of a lobar, segmental, or subsegmental defect on 2 views. When these data were compared with our previous study, statistical analysis found no difference in the prevalence of abnormal Q scans in the 2 groups. We conclude that among young normal persons, abnormal Q scans are extremely uncommon and the prevalence of significant Q defects is not influenced by smoking.

The effect of degradable starch microspheres (DSM) on the pharmacokinetics of 4 drugs administered via the hepatic artery was studied in 5 patients with colon carcinoma metastatic to the liver. The 4 drugs were 99m-technetium diethylenetriamine pentaacetic acid (99mTc-DTPA), an agent which is not metabolized in the liver, and floxuridine, doxorubicin, and mitomycin, agents which undergo hepatic metabolism to varying extents. DSM transiently decreased arterial blood flow to normal liver an average of 64% and to hepatic tumor an average of 78%. DSM increased tumor exposure to DTPA by a mean of 1.71-fold, and increased hepatic exposure by 1.46-fold, but did not affect total plasma exposure. In contrast, DSM did reduce total plasma exposure to floxuridine by a mean of 34%, and to mitomycin by 20%. No information was available on the effect of DSM on plasma doxorubicin levels which never exceeded the limits of detection. Variation in the injection rate of DSM did not appear to influence the relative advantages produced in tumor or plasma AUCs. The estimated increase in tumor exposure produced by DSM was 3.8-fold for floxuridine, and 3.0-fold for mitomycin. These results reflect the differences in extent of hepatic metabolism of these agents, and agree closely with predictions made from mathematical models. Although DSM improved the therapeutic index, the increase in tumor exposure was insufficient to produce significant tumor regression.

Digital video subtraction angiography (DVSA) after central intravenous administration of contrast media was used in experimental animals and in patients with suspected coronary artery disease to quantitate left ventricular dimensions and regional and global contractile function. In animals, measurements of left ventricular (LV) volumes, wall thickness, ejection fraction, segmental contraction, and cardiac output correlated closely with sonocardiometry or thermodilution measurements. In patients, volumes and ejection fractions calculated from mask mode digital images correlated closely with direct left ventriculography. Global and segmental contractile function was displayed in patients by ejection shell images, stroke volume images, and time interval difference images. Central cardiovascular function was also quantitated by measurement of pulmonary transit time and calculation of pulmonary blood volume from digital fluoroscopic images. DVSA was shown to be useful and accurate in the quantitation of central cardiovascular physiology.

The effect of exercise training on myocardial perfusion was assessed using initial and 1-year thallium-201 (Tl-201) exercise studies in 56 patients with stable coronary artery disease (CAD). Subjects had been randomized into a trained group participating in supervised exercise three times per week and a control group. Indices (non-dimensional units) based on computer-analyzed circumferential count profile from nine regions of the heart, assessed in three projections, were used to eliminate observer bias and more accurately quantitate Tl-201 distribution and 4-hour washout. There was serial improvement of the global distribution count profiles in 21 of 27 (77.8%) of the trained and in 9 of 29 (31.0%) of the control subjects (p less than 0.001). The mean interval change in global initial distribution over the year period was 5 +/- 13 (mean +/- SD) in the trained and -6 +/- 14 in the control groups (p less than 0.003). The mean initial distribution of the trained group had improvement in all nine regions (significant in three), while the control group showed mean improvement in only one of nine regions. Additionally, the trained group showed improvement in the mean washout in five of nine regions (significant in three), while no mean regional washout improvement occurred in the control group. Thus, in this group of patients with stable CAD, exercise training resulted in apparently improved cardiac perfusion evidenced by enhance Tl-201 uptake and washout.

Previously we validated a method for quantification of 201TI myocardial stress distribution and washout in which the patient's stress and washout circumferential profiles are compared with observed normal limits. The present study reports the results of a multicenter trial in which this method, utilizing normal limits from our institution, was employed to evaluate the presence, location, and extent of coronary artery disease (CAD). The normal limits utilized were generated from 49 patients having a low likelihood of CAD. The study population included 157 patients from four centers in the United States and Canada as well as a comparative prospective population from Cedars-Sinai Medical Center (CSMC) of 51 patients with CAD, 30 patients with normal coronary arteriograms, and 30 additional low-likelihood normals. The results in the combined centers regarding overall detection of CAD revealed a sensitivity of 84% and a frequency of test normality in the patients with low likelihood of CAD of 88%, compared to a sensitivity of 82% and true normalcy rate of 83% obtained in the prospective CSMC population. The sensitivity for detecting disease increased according to the extent of angiographic CAD in both the multicenter sites and the prospective CSMC group. Regarding localization of disease, similar sensitivities and specificities for detecting disease in individual coronary arteries were found in the multicenter sites and the prospective CSMC population. The results indicate that our method for quantifying 201TI stress-redistribution scintigrams utilizing standard normal limits can be applied at other institutions using a variety of scintillation cameras with similar accuracy to that currently obtained at our institution.

Previous reports have suggested that left ventricular ejection fraction can be assessed by recording the passage of peripherally administered radioactive bolus through the heart. The accuracy and validity of this technique were examined in 20 patients undergoing diagnostic cardiac catheterization. 99m-Tc-human serum albumin was injected via a central venous catheter into the superior vena cava and precordial activity recorded with a gamma scintillation camera interfaced to a small digital computer. A computer program was designed to generate time-activity curves from the left ventricular blood pool and to calculate left ventricular ejection fractions from the cyclic fluctuations of the left ventricular time-activity curve which correspond to left ventricular volume changes during each cardiac cycle. The results correlated well with those obtained by biplane cineangiocardiography (r equals 0.94) and indicated that the technique should allow accurate and reproducible determination of left ventricular ejection fraction. The findings, however, demonstrated that the time-activity curve must be generated from a region-of-interest which fits the left ventricular blood pool precisely and must be corrected for contributions arising from noncardiac background structures. This nontraumatic and potentially noninvasive technique appears particularly useful for serial evaluation of the acutely ill patient and for follow-up studies in nonhospitalized patients.

Graded, sequential, rest/exercise, gold-195m (Au-195m) (T1/2 = 30 seconds), first-pass ventriculography and thallium-201 (T1-201) single-photon emission computed tomography (SPECT) were performed simultaneously during a single, electrocardiograph-monitored, bicycle stress test in 24 individuals. The technical aspects and logistics involved in performing this combined radionuclide study are stressed in this preliminary report. Fourteen healthy volunteers each had a normal left ventricular ejection fraction and wall-motion response, along with normal Tl-201 perfusion and washout, as determined by both visual and quantitative analysis of the tomographic sections. Each of ten patients with coronary artery disease had at least one abnormality of these parameters. We suggest that it is technically feasible to evaluate both cardiac function and myocardial perfusion simultaneously by combining Au-195m ventriculography and T1-201 SPECT imaging into a single, noninvasive, diagnostic package.

The most urgent diagnosis addressed by cholescintigraphy is acute cholecystitis. By administering low-dose intravenous morphine sulfate to patients undergoing cholescintigraphy (who demonstrate visualization of both the common bile duct and intestine and nonvisualization of the gallbladder), the time required to complete the study has been reduced to a maximum of 90 minutes. One hundred twenty-eight patients underwent cholescintigraphy for clinically suspected acute cholecystitis. Forty patients received intravenous morphine sulfate during the procedure. In patients who received morphine sulfate during the examination, the sensitivity of cholescintigraphy for the diagnosis of acute cholecystitis was 100%; the specificity was 85%.

Ventilation-perfusion lung imaging appears to be a significant nonivasive means of supporting the clinical diagnosis of Swyer-James syndrome. Three cases are presented which display characteristic delayed washout of xenon from a small or normal-sized, underperfused hyperlucent lung.

The results of rest and exercise ECG, 201Tl myocardial perfusion imaging and equilibrium radionuclide angiography were analyzed in 71 consecutive patients referred for diagnosis or evaluation of coronary artery disease (CAD). In 45 patients the diagnosis was established either by catheterization or typical history. In this group the overall sensitivity for rest/exercise ECG was 66%, for 201Tl scans 74%, for both combined 79% and for the ejection fraction response to exercise determined by radionuclide angiography 97%. If only the exercise response was considered, the corresponding sensitivity values were 58% (ECG), 50% (201Tl scans), 71% (ECG + 201Tl) and 97% (radionuclide angiography). The specificity for coronary artery disease was determined to be 71% for ECG, 86% for 201Tl scans and 42% for radionuclide angiography. All patients with false-positive results by radionuclide angiography had cardiomyopathies, thus this test has a high specificity for left ventricular dysfunction rather than for CAD alone. Criteria developed from the analysis of the test results in the 45 patients with definite diagnoses were then applied to the evaluation of 26 additional patients with atypical chest pain. A diagnosis could be made in all but 5 of them and radionuclide angiography was again the single most reliable test. Based on this study a new approach for the noninvasive evaluation of patients with suspected coronary artery disease is proposed.

To validate ejection fraction (EF) calculations from 5 and 2 minutes of multiple-gated equilibrium radionuclide angiographic data and to establish its utility during alterations in cardiac performance, we studied 38 patients with chest pain suggestive of coronary artery disease. Twenty-four patients underwent contrast ventriculography (CV) as well as first-pass (FP) and equilibrium (EQ) radionuclide angiography at rest, and 14 additional patients had both radionuclide tests performed at rest as well as during peak supine bicycle exercise. The resting 5-min acquisition ejection fractions were compared between each method and the following correlations were generated: r = .92, n = 24 (CV-EQ), r = .92, n = 24 (CV-FP), and r = .95, n = 38 (FP-EQ). The variability of EQ-EF calculations between two independent observers was less than 2%; the mean absolute difference between two sequential 2-min acquisitions and the 5-min recordings was -.1 +/- 1.6%, and the reproducibility of sequential 2-min ejection fractions was excellent (r = .98). EQ and FP ejection fractions at symptom-limited exercise correlated well (r = .96, n = 14). We conclude that equilibrium radionuclide angiography is a valid method to measure EF both at rest as well as during peak exercise even when 2-min acquisition periods are used.

A case of increased Ga-67 uptake in a patient with active acne vulgaris is reported. The scan was requested in a search for metastatic testicular carcinoma or bleomycin pulmonary toxicity. Careful clinical evaluation including physical examination was necessary in order to avoid an erroneous scan interpretation.

The radionuclide bone scan 3 months after the initiation of treatment for advanced cancer of the prostate occasionally shows apparent progression of individual lesions despite clinical improvement. To determine the incidence and clinical significance of this so-called flare phenomenon, serial bone scans were reviewed in 33 patients with carcinoma of the prostate and bony metastases, who were receiving endocrine treatment for the first time. A flare reaction was seen in two (6%) of 33 bone scans obtained 3 months after initiation of treatment. A flare reaction on bone scan is an unusual phenomenon in prostatic cancer; in general, serial scans accurately depict the activity of bony metastases in these patients.

We measured right and left ventricular ejection fracttion (EF) from high frequency time-activity curves obtained during the initial passage of an intravenous bolus of 99mTc (Sn) pyrophosphate. In 22 normal controls right ventricular EF averaged 0.52 +/- 0.04 (SD). In 24 acute anterior or lateral infarction patients right ventricular EF was normal (0.56 +/- 0.10), while left ventricular EF was reduced (0.45 +/- 0.10, P less than 0.001 vs controls). In 19 acute inferior infarction patients left ventricular EF also was depressed (0.51 +/- 0.09, P less than 0.001 vs controls). Among 7 of 19 inferior infarction patients with right ventricular by scintigraphy, right ventricular EF was reduced (0.39 +/- 0.05; P less than 0.001 vs normals; P less than 0.01 vs inferior infarction patients without right ventricular involvement). In the latter group right ventricular EF averaged 0.51 +/- 0.10 (NS vs normals). We conclude 1) a single injection of 99mTc (Sn) pyrophosphate can identify right and left ventricular dysfunction and infarct location in acute myocardial infarction, 2) right ventricular EF is well-preserved except when inferior infarction involves the right ventricle.

Manganese, a trace metal, is known to localize in mitochondria. Because mitochondria are abundant in heart muscle, the possible utility of radioactive manganese as a myocardial imaging agent was examined in 25 rats and six dogs. Myocardial uptake of Mn-54 in rats was found to exceed that of thallium-201; myocardium-to-blood ratios averaged 306:1 versus 48:1 for Tl-201. In the dog, uptake of Mn-54 by ischemic myocardium was reduced by 17-75% compared with normal myocardium. Thus, radioactive manganese appears promising as an intravenous myocardial imaging agent, and might be useful in studying the function of myocardial mitochondria by external imaging.

An air-cart that operates on the laminar air flow principle was designed to permit easy movement of a scintillation camera detector by one operator. Air flow is obtained from the hospital main supply which is available to each room.

A simple method to insure the reproducibility of patient positioning is described. The system uses an adjustable frame fastened to the camera head and two light sources. The light sources project two circles of light on the patient. These reference points are marked on the patient's skin with a felt pen. If the patient moves or requires a follow-up study, these two reference points can be used to reposition the patient exactly. Comparison of the light-sources method with the persistence-scope method showed a significant improvement in accuracy with the former.

We studied the specificity of uptake of infarct-imaging agents for reversibly or irreversibly injured myocardium independently of blood flow by using intact beating fetal mouse hearts in organ culture. Reversible injury resulted from deprivation of oxygen and glucose for 4 hours at 37 degrees C; irreversible injury, from similar deprivation at 42 degrees C. At the end of the insult, uptake of 99mTc(Sc)-labeled pyrophosphate, glucoheptonate, or tetracycline was markedly increased in irreversibly damaged and, to a lesser degree, in reversibly injured hearts. After 24 hours of recovery, necrotic hearts accumulated even more pyrophosphate and tatracycline but less glucoheptonate. Uptake of radioiodinated tetracycline increased only in irreversibly injured hearts. Pyrophosphate uptake was not reduced in hearts cultured in calcium-free medium. These finding suggest that 99mTc(Sn)-labeled pyrophosphate, tetracycline, and glucoheptonate preferentially localize in irreversibly damaged myocardium; the 99mTc(Sn) complex modifies the specificity of uptake; and the uptake of 99mTc(Sn)-pyrophosphate appears unrelated to calcium uptake.

A patient with fungal splenic abscesses is presented in whom multiple noninvasive diagnostic imaging modalities were available for correlation. Of the five imaging modalities, three (Gallium-67, ultrasound and computed tomography) were diagnostically useful, while two (liver-spleen scan and In-111 white blood cell scan) were not as useful. This case also stresses the use of repeated studies correlating with clinical impressions to obtain an accurate diagnosis in a potentially life-threatening condition such as splenic abscess.

To assess the response of the right and left ventricles to the subcutaneous administration of terbutaline sulfate, a beta-2 selective agonist, we evaluated 14 patients with chronic obstructive pulmonary disease (COPD) with equilibrium radionuclide angiography (RNA). Prior to injection, eight patients (57%) had an abnormal right ventricular ejection fraction (RVEF), four (29%) had a low left ventricular ejection fraction (LVEF), and three (21%) had low ejection fractions of both ventricles. After terbutaline injection, RVEF increased in 13 of 14 patients (93%) by 17 +/- 8% (p less than 0.001) while LVEF increased in all patients by 15 +/- 7% (p less than 0.001). Both left and right ventricular end-diastolic volumes decreased (p less than 0.01), while stroke volume was unchanged. Cardiac output rose by 0.8 +/- 1.3 L/min (p less than 0.05), primarily due to the increase in heart rate (10 bpm, p less than 0.001), since stroke volume did not significantly change. We conclude that in patients with COPD subcutaneous terbutaline has significant beta-1 cardiac effects; it increases the heart rate and decreases cardiac size.

Studies of the washout of radioactive 133xenon were performed in six normal subjects and six patients with chronic obstructive pulmonary disease during normal and diaphragmatic breathing. Subjects were unable to change the distribution of ventilation with diaphragmatic breathing. In all normal subjects and in three of the six subjects with chronic obstructive pulmonary disease, overall washout improved with diaphragmatic breathing. It is suggested that this change was related to the slower, deeper tidal volumes used by these subjects during diaphragmatic breathing.

Syrup of ipecac (SOI) is a commonly used emetic for toxic ingestions. A preliminary study was undertaken to quantify the efficacy of SOI-induced emesis. Three groups of adult subjects fasted overnight before ingestion of 1 mCi of Tc-99m human serum albumin-sucralfate. Sucralfate is minimally absorbed from the gastrointestinal tract and has a gastric clearance half-time of 90 minutes, approximately equal to that of solid foods. At 5, 30, and 60 minutes after ingestion of radiolabeled sucralfate (RSC), subjects were given a standard dose of 30 ml SOI and 240 ml of water. Gastrointestinal tract images were obtained both at the time of ingestion of RSC and 60 minutes after ingestion of SOI. Regions-of-interest were drawn and activity measured over the stomach and small bowel with correction for physical decay. Those subjects (N = 10) treated at 5 minutes after ingestion retained a mean value of 17% of the administered RSC by 60 minutes. The group (N = 5) treated at 30 minutes after ingestion retained a mean value of 41%, while those (N = 5) treated at 60 minutes retained a mean value of 56%. The results tend to confirm the efficacy of SOI-induced emesis when SOI is given promptly (i.e., 5 minutes) following ingestion, and generally support efforts to assure widespread immediate availability of SOI for toxic ingestions.

This paper presents the profiles of left ventricular ejection fraction (EF) during and following supine bicycle exercise in normal subjects and in patients with coronary heart disease, as well as the relationship of the described patterns to clinical parameters. Twenty normal men and 40 patients with coronary artery disease were studied using gated equilibrium radionuclide angiography (EQ-EF). In the normals, during exercise, EF increased by a mean of 25% of the resting value, with an increase of no less than 11%. The exercise-limiting symptom in patients with coronary artery disease was angina pectoris in 20 and fatique in the other 20 patients. In the angina patients, there was a mean decrease in EF of 20%, and in the other coronary artery disease patients ejection fraction change little. Only two patients with coronary artery disease increased from a normal resting value to peak exercise by more than 11%, and they had isolated right coronary lesions. An "overshoot" elevation of ejection fraction above resting levels was demonstrated following termination of exercise in most patients. The patients with a significant fall in exercise ejection fraction more frequently had abnormal exercise-induced ECG changes as well as abnormal left ventriculograms and more severe coronary artery disease at cardiac catheterization than the patients with little change in ejection fraction. We conclude that 1) normals could be separated from most patients with significant coronary artery disease in this study population; 2) ejection fraction must be measured at maximal exercise for it to have diagnostic value, since there could be normal rise before and after peak exercise and an abnormal response missed; and 3) the ejection fraction response to exercise reflects the severity of the underlying coronary artery disease. The described patterns of exercise-induced changes in left ventricular ejection fraction are important to consider when using this new technique to diagnose and evaluate patients with coronary artery disease.

The accuracy and sensitivity of myocardial imaging using intravenous Rb-81 in delineating the extent and subsequent changes in regional myocardial perfusion abnormalities were examined serially in 12 patients one to 510 days after an acute myocardial infaraction. Definite regions of decreased Rb-81 uptake were noted in 10 patients with transmural infarction. There was excellent correlation between the site of perfusion abnormalities, the electrocardiographic infarct location and the region of segmental wall motion disorders. Follow-up studies revealed in 8 of 11 patients a decrease in the extent of the perfusion defect, which was associated with an improvement in the extent and/or severity of regional wall motion disorders. Conversly, wall motion abnormalities did not change in the remaining three patients in whom perfusion abnormalities persisted unchanged. We conclude that intravenous myocardial imaging permits visualization of myocardial perfusion abnormalities early after acute myocardial infaraction. Serial imaging allows detection of changes in the extent of perfusion abnormalities, and, thus, might provide useful information with respect to the patient's prognosis and the effects of therapeutic interventions.

The prevalence of abnormal pulmonary perfusion (Q) scans in persons without cardiopulmonary disease has not been well defined; this prevalence could impact on the current diagnostic approach to those in whom pulmonary embolic disease is suspected. In prior studies, we found that Q scan defects, particularly lobar or segmental defects, are rarely present in normal young smokers and nonsmokers. To determine if normal nonsmokers of an older age group have a higher prevalence of Q defects, we performed 6-view Q scans in 40 subjects 32 to 49 yr of age who had no known cardiopulmonary disease. Each subject had undergone a history, physical examination, electrocardiogram, spirometry, and posteroanterior chest roentgenogram prior to scanning. All Q scans were interpreted blindly and independently by 2 experienced readers. No subject demonstrated a lobar or segmental defect on 2 views. One subject with scoliosis had a subsegmental defect corresponding to a prominent aortic arch on the chest roentgenogram. We conclude that abnormal Q scans are extremely uncommon among normal nonsmokers 30 to 49 yr of age.

The ultimate clinical value of thallium-201 imaging depends, to a large extent, on the technical quality of the test and on an understanding of the fundamental clinical and physiologic principles of this imaging mode. This article offers an in-depth discussion of the underlying biokinetic concepts of thallium-201 imaging as well as the practical and technical considerations involved in its successful implementation.

The left ventricular ejection fraction was determined serially with radioisotope angiography in 63 patients with acute myocardial infarction. After the peripheral injection of a bolus of technetium-99m, precordial radioactivity was recorded with a gamma scintillation camera and the ejection fraction calculated from the high frequency left ventricular time-activity curve. Since this technique requires no assumptions with respect to left ventricular geometry, it is particularly useful in patients with segmental left ventricular dysfunction. Serial measurements during the first 5 days after hospital admission were made in 50 patients, 30 of whom were studied during the subsequent 2 to 39 months (mean 19.9 months). Late follow-up serial studies were also performed in an additional 13 patients who had only one measurement of the left ventricular ejection fraction during the early postinfarction period. Early after infarction, the left ventricular ejection fraction was normal (more than 0.52) in only 15 of the 63 patients, and averaged 0.52 +/- 0.05 (standard deviation) in the 27 patients with an uncomplicated infarct. The ejection fraction was reduced in 24 patients with mild to moderate left ventricular failure (0.40 +/- 0.05, P less than 0.0001) and in the 12 patients with overt pulmonary edema (0.33 +/- 0.07, P less than 0.0001). In 35 patients the ejection fraction correlated with the mean pulmonary arterial wedge pressure (r = 0.72). In 15 patients with normal left ventricular wall motion by heart motion videotracking, the ejection fraction was significantly higher (0.53 +/- 0.08) than in the 26 patients with regional left ventricular dysfunction (0.41 +/- 0.10, P less than 0.0001). During the early postinfarction period, the left ventricular ejection fraction improved in 55 percent of patients and remained unchanged or decreased in 45 percent. A further increase in the ejection fraction was noted in 61 percent of patients during the late follow-up period. Patients with an initially low or decreasing ejection fraction had a significantly greater incidence of early mortality and left ventricular dysfunction (P less than 0.02) than those whose ejection fraction was normal or improved to normal early after infarction. These data indicate that the ejection fraction is a sensitive indicator of left ventricular function after acute myocardial infarction and that serial measurements are helpful in predicting early mortality and morbidity.

Left ventricular volumes calculated from mask-mode (MM) images obtained by digital intravenous ventriculography (DIV) were compared with volumes determined from direct contrast images (CV), thermodilution and sonomicrometer measurements in six anesthetized dogs in which volumes were varied by isoproterenol and phenylephrine infusions. Short and long axis sonomicrometer crystals allowed continuous measurement of cardiac size and function. The MM and CV ejection fractions and volumes correlated well with each other (r greater than or equal to 0.96) through the MM volumes consistently underestimated the CV volumes by 12 +/- 3%. Analyzing each dog individually, both CV and MM volumes and ejection fractions correlated well with sonomicrometer results. In addition CV and MM estimates of stroke volume correlated well (r greater than or equal to 0.91) with the thermodilution values, although the CV values exceeded the thermodilution value by 17 +/- 4%. We conclude that MM analysis of left ventricular function correlates well with standard measures of cardiac dimensional changes and agrees with, though underestimates, the simultaneous nonsubtracted contrast ventriculographic images.

To determine the validity of cardiac output estimates obtained by digital video subtraction angiography (DVSA), they were compared with thermodilution values in 6 anesthetized dogs. Multiple levels of cardiac output were produced in each dog by graded openings of peripheral arteriovenous fistulas. Both direct contrast and mask-mode images were evaluated. There was good correlation between thermodilution and direct contrast values (r = 0.88) as well as between thermodilution and mask-mode values (r = 0.89), though the mask-mode outputs were 12 +/- 1.1% less than the direct contrast values (p less than 0.05). Direct contrast and mask-mode values correlated well (n = 6; r greater than or equal to 0.95). Digital outputs exhibited little variation, indicating excellent reproducibility. These results demonstrate the validity of area-length estimates of cardiac output by DVSA.

A noncomputerized, count-based technique for the determination of left ventricular ejection fraction (LVEF), which does not use geometric assumptions of left ventricular shape, was developed. The noncomputerized technique and computerized multigated ventriculography using both fixed and variable region-of-interest (ROI) methods were performed on 16 patients. The LVEFs obtained with the noncomputerized technique correlated well with both the fixed ROI computerized technique (r = .87) and the variable ROI computerized technique (r = .86). It is concluded that when a computer is not available, the noncomputerized technique is a valid alternative for the determination of LVEF in resting patients in stable sinus rhythm.

In-111-labeled leukocytes were administered to 13 patients on continuous ambulatory peritoneal dialysis in order to locate catheter-associated infections. Using a marker to indicate the catheter exit site, infections of the catheter tunnel were correctly identified prior to surgery in 4 patients with relapsing peritonitis and infections of the exit site were diagnosed in 5 out of 7 patients. There were no false positives or negatives as documented by surgery or follow-up. The authors conclude that In-111-leukocyte scintigraphy appears to be accurate in diagnosing peritoneal infections of the dialysis catheter tunnel.

Digital intravenous ventriculography lends itself readily to quantitative assessment of ventricular wall motion with computer algorithms. Forty-five patients referred for cardiac catheterization were studied by digital intravenous ventriculography (mask mode) and direct ventriculography in the 30 degrees right anterior oblique position. Quantitative wall motion was analyzed by a radial shortening method applied to both studies. Lower limits of normal radial shortening were determined for each technique and used to determine the presence or absence of wall motion disorders. The inter- and intraobserver variability of radial shortening measurements was +/- 5.3 and +/- 8.8%, respectively, with maximal discrepancies of -6 and +7% fractional shortening units. The overall agreement between the two techniques in wall motion assessment was 87% (274 of 315 radii). A subset of patients also underwent atrial pacing, and a second digital intravenous ventriculogram was obtained (5 normal subjects and 15 patients with coronary artery disease). Although analysis of wall motion at rest showed a poor sensitivity for detection of significant coronary stenoses, nine of nine patients with coronary artery disease and normal wall motion at rest showed a quantitative decrease in radial wall motion after atrial pacing. Thus, digital intravenous ventriculograms can be used to provide quantitative wall motion analyses that show a high degree of agreement with those of standard, direct left ventriculography. Atrial pacing can be used to increase the sensitivity of wall motion analysis for the detection of significant coronary disease.