Time to completed redistribution of thallium-201 in exercise myocardial scintigraphy: relationship to the degree of coronary artery stenosis

The relationship between the severity of coronary artery stenosis and the time to completed redistribution of thallium 201 (TI-201) defects following maximal exercise was investigated in 59 patients undergoing stress-redistribution TI-201 scintigraphy, coronary angiography, and contrast ventriculography. Multiple view TI-201 scintigrams were obtained, beginning 6 minutes (immediately post stress), less than 1 hour (early), 3 to 5 hours (average), and 18 to 24 hours (late) following intravenous TI-201 injection at peak exercise. Angiographic lesions were grouped into five levels of severity by percent stenosis. In the 107 defects which were seen on the immediate post stress images, early redistribution was noted in 15 (14%) and late redistribution was found in 23 (21%). In addition, there was a correlation (r = 0.56) between the time to completed redistribution and the severity of the coronary artery stenosis (p = 0.001). In comparison to defects with early and average redistribution, the segments contralateral to those with defects showing late redistribution more often had a critical stenosis supplying that segment. The frequency of myocardial infarction on ECG and the number of segments with akinetic and dyskinetic wall motion were less in defects undergoing late rather than no redistribution. Thus the time to completed TI-201 redistribution following stress appears to be related to the severity of stenosis in the coronary artery supplying the defect. Also, late redistribution is associated with the presence and early redistribution with the absence of a significant stenosis in the coronary artery to the contralateral segment.

Clinical evaluation of seven-pinhole tomography for the detection and localization of coronary artery disease: comparison with planar imaging using quantitative analysis of myocardial thallium-201 distribution and washout after exercise

The development of quantitative techniques to assist in the analysis of planar thallium-201 stress-redistribution scintigrams has led to improved abilities of this modality to detect the presence of and to localize significant coronary artery disease (CAD). This fact has encouraged the reevaluation of its capabilities relative to other types of scintigraphic data collection, including seven-pinhole tomography. We have undertaken a comparison of planar scintigraphy and seven-pinhole tomography to detect in 40 exercised patients (23 with angiographically demonstrated CAD, eight with normal coronary angiograms, and nine with less than or equal to 1% likelihood of having CAD) the presence of significant CAD and to localize it correctly to an individual coronary artery. Emphasis was placed on similar imaging conditions and on analysis of images by the same quantitative program of TI-201 distribution and washout. Both techniques were found to be highly sensitive and specific for disease detection and localization. Importantly, seven-pinhole tomography did not significantly improve results.

Enhanced detection of proximal right coronary artery stenosis with the additional analysis of right ventricular thallium-201 uptake in stress scintigrams

The value of right ventricular thallium-201 analysis in detecting proximal right coronary artery stenosis in exercise myocardial scintigraphy was analyzed in 52 patients, 27 with and 25 without proximal right coronary artery stenosis. For the detection of proximal right coronary artery stenosis, the sensitivity and specificity of thallium scintigraphic analysis were 59 and 88% for a right ventricular abnormality, 67 and 68% for a left ventricular inferior wall abnormality, and 93 and 56% for an abnormality of either. When both right and left ventricular thallium images were abnormal, all 9 patients had proximal right coronary artery stenoses, and when both were normal, 26 of 28 patients had a normal proximal right coronary artery. The sensitivity and specificity of blood pool scintigraphic variables during exercise (right ventricular ejection fraction and left ventricular inferior wall motion) were not significantly different for detection of proximal right coronary artery stenosis. Thus, the additional analysis of the right ventricle on thallium-201 stress scintigrams can improve the detection of proximal right coronary artery stenosis. When both right ventricular and left ventricular thallium scintigrams are abnormal (or normal), the ability to predict the presence (or absence) of proximal right coronary artery stenosis is very high.

Meperidine-induced sinusoidal fetal heart rate pattern and reversal with naloxone

A case of sinusoidal fetal heart rate (FHR) pattern in association with maternal intrapartum administration of meperidine is presented. The sinusoidal pattern was reversed after maternal intrapartum administration of naloxone. The significance of this problem and the management of patients with sinusoidal FHR are discussed. The conclusion is reached that iatrogenic causes may at times precipitate a sinusoidal FHR pattern and conservative management may be appropriate.

The significance of 1-131 scan dose in patients with thyroid cancer: determination of ablation: concise communication

Twenty-four patients with differentiated thyroid cancer were studied with diagnostic I-131 neck chest scans after having undergone bilateral subtotal thyroidectomy and initial I-131 therapy with either 30- or 100-mCi doses. With an endogenous stimulation protocol, follow-up studies were performed with neck and chest scans using 2 and 10 mCi I-131. A 400% increase in sensitivity was found with a 10-mCi dose relative to a 2-mCi dose. Comparison with therapeutic doses of 30 and 100 mCi resulted in further increases in the detection of residual iodine-avid tissue. We conclude that a 2-mCi or lower dose of I-131 is inadequate in evaluating residual iodine-avid tissue visually in patients with thyroid cancer. The study does not answer the critical question of whether it is necessary to treat a patient presenting a negative 2-mCi but a positive 10-mCi scan. It may be appropriate to define ablation visually as well as clinically, with further studies directed toward determining a treatment rationale in this patient population.

Space/time quantitation of thallium-201 myocardial scintigraphy

A comprehensive method is described for quantitation of the spatial distribution of TI-201 in the myocardium and its changes with time. The method, applied here to 51 patients, uses bilinear interpolative background subtraction to compensate for tissue crosstalk, and circumferential profiles to quantitate the relative radionuclide activity in the myocardium as an angular function with origin at the center of the left-ventricular cavity. In addition, washout circumferential profiles are calculated as percent washout from the stress circumferential profiles. Abnormal thallium distribution or washout is identified by automatic computer comparison of each patient's profiles with the corresponding limits of normal profiles, determined from the pooled profiles of 31 normal patients. In these 31, the computer output was normal in all cases. In 20 patients with angiographically documented coronary artery disease, 19 were determined to be abnormal by this method. This new computerized treatment provides accurate objective assessment of the presence of coronary artery disease.

False-positive lung imaging: inadvertent injection into a pulmonary artery catheter

A case of a ventilation-perfusion mismatch seen post-operatively in a patient with chest pain is reported. There was absence of perfusion to the right lung, with relatively normal ventilation. The study was initially interpreted as indicating a high probability of pulmonary embolus. It was then discovered that the injection had been inadvertently made into a Swan-Ganz catheter, with its tip in the left main pulmonary artery. The mismatch was therefore iatrogenic and not related to pulmonary embolus. The false-positive lung imaging which resulted has not been previously reported in the literature.

The abnormal hepatic scan of chronic liver disease: its relationship to hepatic hemodynamics and colloid extraction

To help explain the characteristic hepatic scan pattern of chronic liver disease, the degree of scan abnormality (scan score, SS) after administration of technetium-99m sulfur colloid (Tc) was compared with data obtained at hepatic vein catheterization in 28 patients. Although SS showed a correlation with wedged hepatic vein pressure (r = +0.491), the scan abnormality was not directly due to portal hypertension because it remained unchanged when the latter was relieved by portacaval shunt. Also, the scan abnormality was found to be unrelated to a low hepatic blood flow. Scan abnormality was not attributable primarily to hyperactivity of the reticuloendothelial (RE) cells of the spleen and bone marrow since fractional clearance (K) of Tc from the blood was decreased rather than increased in patients with abnormal scans. SS was inversely correlated with K or Tc (r = -0.575) and with hepatic extraction efficiency for Tc (r = -0.673), showing that the basic abnormality was poor extraction of the colloid by the RE cells of the liver with a resultant increase in the amount available for extrahepatic localization. Indirect evidence suggests that this poor extraction of colloid is due to intrahepatic shunts bypassing hepatic RE cells.

BOXER'S BURSITIS

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SPONTANEOUS FRACTURE OF THE FIRST RIB DUE TO MUSCLE PULL, A Case Report

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FRACTURE OF THE OLECRANON PROCESS DUE TO MUSCLE PULL WITH THE FOREARM IN HYPEREXTENSION

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