Prevalence of acute pulmonary embolism in central and subsegmental pulmonary arteries and relation to probability interpretation of ventilation/perfusion lung scans

PURPOSE: The purpose of this investigation is to determine the prevalence of acute pulmonary embolism (PE) limited to subsegmental pulmonary arteries. BACKGROUND: Contrast-enhanced helical (spiral) and electron-beam CT, in the hands of experienced radiologists who are skillful with this modality, are sensitive for the detection of acute PE in central pulmonary arteries, but have a low sensitivity for the detection of PE limited to subsegmental pulmonary arteries. The potential for CT to diagnose PE, therefore, is partially dependent on the prevalence of PE limited to subsegmental pulmonary arteries. METHODS: Data are from the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). The largest pulmonary arteries that showed PE, as interpreted by the PIOPED angiographic readers, were identified in 375 patients in PIOPED with angiographically diagnosed PE. RESULTS: Among all patients with PE, 6% (95% confidence interval [CI], 4 to 9%) had PE limited to subsegmental branches of the pulmonary artery. Patients with high-probability ventilation/ perfusion (V/Q) scans had PE limited to subsegmental branches in only 1% (95% CI, 0 to 4%). Among patients with low-probability V/Q lung scans, 17% (95% CI, 8 to 29%) had PE limited to the subsegmental branches. Patients with low-probability V/Q scans and no prior cardiopulmonary disease had PE limited to the subsegmental pulmonary arteries in 30% (95% CI, 13 to 53%), whereas patients with low-probability V/Q scans who had prior cardiopulmonary disease had PE limited to subsegmental pulmonary arteries in 8% (95% CI, 2 to 22%) (p < 0.05). CONCLUSION: Based on data from all patients with PE in PIOPED, the prevalence of PE limited to subsegmental pulmonary arteries is low, 6%. PE limited to subsegmental pulmonary arteries was most prevalent among patients with low-probability V/Q scans, particularly if they had no prior cardiopulmonary disease.     

Ventilation-perfusion lung scanning and spiral computed tomography of the lungs: competing or complementary modalities?

The recently developed technique of spiral computed tomographic angiography (CTA) is being used for the detection of pulmonary emboli (PE), and several studies have assessed its accuracy using pulmonary angiography as the gold standard. CTA shows a high level of accuracy in the detection of pulmonary emboli in segmental or larger central vessels. The specificity is high enough to eliminate the requirement for angiography if a positive CTA result is found. The main factor limiting the sensitivity of CTA is the frequency of peripheral emboli in the vessels outside the central chest field covered by CTA. The incidence of such peripheral emboli varies in different reports from 0% to 36%, and their significance remains arguable. Interpretative criteria for V./Q.- lung scintigraphy have been refined as a result of the lessons learned from the PIOPED study. Using these modified criteria, and taking into account the prior probability of PE based on the presence or absence of clinical risk factors, treatment decisions can be reasonably made in patients in the following categories: those with normal lung scans, those with high probability scans and high prior probability of PE, and those with low probability scans and low clinical suspicion. Patients with intermediate probability or indeterminate scans, and those in whom the scan results conflict with the clinical expectation, will need further tests. Ultrasound examination of the leg veins, if positive, will select a further subgroup of patients for active treatment. Patients with a negative or inconclusive ultrasound result, who previously have been candidates for pulmonary angiography, can now go on to CTA. The advantages in specificity which CTA offers will make it an important part of the diagnostic workup for selected patients, but in view of its increased cost and high radiation dose compared with V./Q. scintigraphy, the argument that CTA should completely replace lung scintigraphy is currently unsupportable.     

Stratification of patients according to prior cardiopulmonary disease and probability assessment based on the number of mismatched segmental equivalent perfusion defects. Approaches to strengthen the diagnostic value of ventilation/perfusion lung scans in acute pulmonary embolism

A categorical diagnosis of "high probability" or "intermediate probability" encompasses a spectrum of diagnostic probabilities of pulmonary embolism (PE) that is not communicated to the referring physician. The diagnostic value of ventilation/perfusion lung scans, in the present investigation, was strengthened by use of a table to determine the likelihood of PE in individual patients on the basis of the observed number of mismatched segmental equivalent perfusion defects. In addition, we tested the hypothesis that stratification of patients according to the presence or absence of prior cardiopulmonary disease may enhance the ventilation/perfusion scan assessment of the probability of PE among both of these clinical categories of patients. Data were derived from the collaborative study of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). Ventilation/perfusion lung scans were evaluated in 378 patients with acute PE and 672 patients in whom suspected PE was excluded. Among patients with no prior cardiopulmonary disease, > or = 1.0 mismatched segmental equivalents was indicative of PE in 102 of 118 (86 percent) vs 113 of 155 (73 percent) among patients with prior cardiopulmonary disease (p < 0.02). Among patients with prior cardiopulmonary disease, > or = 2 mismatched segmental equivalents were required to indicate > or = 80 percent probability of PE. Stratification on the basis of the presence or absence of prior cardiopulmonary disease, therefore, enhanced the ability of ventilation/perfusion scan readers to assign an accurate positive predictive value and specificity to individual patients based on the observed number of mismatched segmental equivalent defects. Among patients with no prior cardiopulmonary disease, fewer mismatched segmental equivalent defects were required to indicate a high probability of PE than were required by PIOPED criteria. The findings from some of these patients, by PIOPED criteria, would have indicated intermediate probability. Some indeterminate probability readings, therefore, will be eliminated among patients stratified with no prior cardiopulmonary disease.     

The use of VisionWorks in visual psychophysics research

PURPOSE: This study was performed to evaluate whether the time interval from injection of technetium Tc 99m (99mTc)-labeled red blood cells to the time of a radionuclide "blush" (positive scan) can be used to improve the efficacy in predicting a positive angiogram. METHOD: A retrospective review revealed 160 patients who received 99mTc-labeled red blood cell scintigraphy for evaluation of massive lower gastrointestinal hemorrhage between 1989 and 1994. Patients were included who demonstrated signs of shock on admission, had an initial decrease in hematocrit of > or = 6 percent, or required a minimum transfusion of two units of packed red blood cells. Scanning duration was 90 minutes, with imaging every 2 minutes. Time interval from injection to a positive scan was analyzed to determine predictability of a positive angiography. RESULTS: Of 160 patients, 86 demonstrated positive scans, of whom 47 underwent angiography. These 47 patients were divided into two groups according to scan results. Group 1 (n = 33) had immediate appearance of blush; Group 2 (n = 14) had blush after two minutes. In Group 1, 20 of 33 patients had a positive angiogram, yielding a positive predictive value of 60 percent (P = 0.033). Of the 14 patients with negative angiograms (13 from Group 1, and 1 with a negative scan), 6 had radiographic occlusion of the inferior mesenteric artery and 1 had spasm of the right colic artery, with scans that blushed in the respective distributions. Excluding these seven patients yielded a positive predictive value of 75 percent (P = 0.0072) for angiography. In patients with a delayed blush (Group 2), 13 of 14 had negative angiograms, yielding a negative predictive value of 93 percent (92 percent excluding those with nonvisualization of the inferior mesenteric artery). Twenty of 21 (95 percent) positive angiograms occurred in Group 1 patients. Of the 27 patients with negative angiograms, 13 were Group 2 patients. CONCLUSION: Patients with immediate blush on 99mTc-labeled red blood cell scintigraphy required urgent angiography. Patients with delayed blush have low angiographic yields. These data suggest that patients with delayed blush or negative scans may be observed and evaluated with colonoscopy.     

Pulmonary function studies after smoke inhalation

Pulmonary function studies were performed within 72 hours of injury in seven patients with smoke inhalation injury diagnosed by positive 133Xe scintiphotographs and in eight patients with burns of similar size but with negative 133Xenon scans. The former patients showed decreased peak flow, decreased flow at 25, 50, and 75 per cent of vital capacity, and an elevated pulmonary resistance. In addition, single breath nitrogen tests revealed evidence of maldistribution of ventilation/perfusion abnormalities. Total lung capacity, functional residual capacity, and compliance (both dynamic and static) were similar in the two groups. Pulmonary function studies can be of assistance in evaluating smoke inhalation, estimating the severity, and following the course of patients with this disorder.     

The mammalian homologue of mago nashi encodes a serum-inducible protein

OBJECTIVE: We prospectively compared the ability of two techniques--bone scintigraphy with single-photon emission computed tomography (SPECT) of the chest and CT of the chest--to reveal potential osteosarcoma metastases of the lung. SUBJECTS AND METHODS: Our study included 27 patients with osteosarcoma who prospectively underwent both bone scintigraphy with SPECT of the chest and CT of the chest. The imaging results were compared with outcome or pathologic analysis of any lung lesions found. RESULTS: Eight (30%) of the 27 patients had pulmonary metastases. Four of these eight patients had positive results on both CT studies and bone SPECT studies, with additional lesions detected with bone SPECT in two of these four patients. The other four patients with pulmonary metastases had positive results on CT studies, whereas the results of bone SPECT studies remained negative. The results of bone SPECT studies were negative in the 19 patients without pulmonary metastases. CT, however, showed abnormalities in seven (37%) of the 19 patients, which were eventually attributed to benign conditions. CONCLUSION: Negative results on a bone SPECT study of the chest should not be used to exclude the possibility of lung metastases. However, if the results are positive, a bone SPECT study can be used to confirm abnormalities seen on CT scans and may also reveal subtle lesions missed on CT scans.     

Utility of scintigraphic methods in patients with fever of unknown origin

BACKGROUND: We assessed the utility of scintigraphy with indium 111-labeled polyclonal human IgG scintigraphy in patients with fever of unknown origin that fulfilled the criteria of temperature of 38.3 degrees C or more for at least 3 weeks and no diagnosis during 1 week of hospital admission. We compared the utility of this technique with results of scintigraphic techniques reported in the literature. METHODS: Data for all patients seen at our university hospital in whom 111In-IgG scanning was performed were analyzed and checked for the criteria for fever of unknown origin. The literature on the utility of scintigraphic techniques in patients with fever of unknown origin was reviewed. RESULTS: We studied 24 patients with fever of unknown origin. In 13 patients, focal 111In-IgG accumulation was observed. In nine (38%) of those, the positive 111In-IgG scintigram led to the final diagnosis; in the other four patients (17%), the scintigraphic findings were not helpful. In the 11 patients with negative 111In-IgG scans, extensive diagnostic workup produced no infection as the final diagnosis in nine patients (38%), one had an abscess in a renal cyst that was detected several months later, and in the other the cause of fever was an infected intravenous line. The overall sensitivity and specificity of 111In-IgG scintigraphy were 81% and 69%, respectively. The positive predictive value was 69% and the negative predictive value was 82%. CONCLUSIONS: Our results show that 111In-IgG scintigraphy significantly contributed to the diagnostic process in patients with fever of unknown origin. A positive scan increased the likelihood of finding the cause of the fever, and a negative scan ruled out an inflammatory component with a high degree of certainty. These data compare favorably with data in the literature concerning other radiopharmaceuticals; a larger prospective evaluation of this technique is indicated.     

Effect of ventilation distribution on aerosol bolus dispersion and recovery

It has been speculated that convective ventilatory inhomogeneities are an important factor influencing aerosol bolus behavior in the compromised lung. Multiple-breath 133Xe washout (MBWXe) is a commonly accepted test of ventilation distribution. By comparing aerosol bolus parameters to MBWXe in 9 healthy subjects and 14 cystic fibrosis patients with mild-to-moderate airway obstruction, we have attempted to discern the effect of altered ventilation distribution on aerosol bolus dispersion and recovery. Aerosol boluses (150-ml width) were delivered to the volumetric penetrations of 250 and 500 ml. Similar tidal volumes (approximately 1.25 liters) and flow rates (0.4 l/s) were used for aerosol bolus and MBWXe maneuvers. Associations between bolus parameters and ventilation distribution were only observed in the cystic fibrosis patients. We conclude that aerosol bolus dispersion and recovery are both influenced by convective ventilatory inhomogeneities induced by airway obstruction in these patients.     

Pulmonary embolism: prospective comparison of spiral CT with ventilation-perfusion scintigraphy

PURPOSE: To compare prospectively the accuracy of spiral computed tomography (CT) with that of ventilation-perfusion scintigraphy for diagnosing pulmonary embolism. MATERIALS AND METHODS: Within 48 hours of presentation, 142 patients suspected of having pulmonary embolism underwent spiral CT, scintigraphy, and (when indicated) pulmonary angiography. Pulmonary angiography was attempted if interpretations of spiral CT scans and of scintigrams were discordant or indeterminate and intermediate-probability, respectively. RESULTS: In the 139 patients who completed the study, interpretations of spiral CT scans and of scintigrams were concordant in 103 patients (29 with embolism, 74 without). In 20 patients, intermediate-probability scintigrams were interpreted (six with embolism at angiography, 14 without); diagnosis with spiral CT was correct in 16. Interpretations of spiral CT scans and those of scintigrams were discordant in 12 cases; diagnosis with spiral CT was correct in 11 cases and that with scintigraphy was correct in one. Spiral CT and scintigraphic scans of four patients with embolism did not show embolism. Sensitivities, specificities, and kappa values with spiral CT and scintigraphy were 87%, 95%, and 0.85 and 65%, 94%, and 0.61, respectively. CONCLUSION: In cases of pulmonary embolism, sensitivity of spiral CT is greater than that of scintigraphy. Interobserver agreement is better with spiral CT.     

Influence of gender on prednisolone effects on whole blood T-cell deactivation and trafficking in rats

Consuming Sauropus androgynus, a Malaysian plant, to reduce body weight began to become fashionable in Taiwan in 1994. According to some reports, people consuming this vegetable developed lung injuries. From July to November 1995, there were 81 nonsmoking women admitted to our hospital. Thirty-six cases had respiratory symptoms/signs and the remaining 45 had no symptoms/signs. We investigated these patients with pulmonary function tests (PFT) and technetium-99m DTPA radioaerosol inhalation lung scintigraphies (DTPA lung scan), a test to evaluate the lung ventilation and alveolar epithelial permeability. Eighteen patients had abnormal results in PFT, including obstructive type (n = 17), restrictive type (n = 5), and both (n = 4). There were 33 patients with abnormalities in DTPA lung scans, including unhomogeneous deposition of DTPA radioaerosols (n = 19), faster clearance of radioaerosols from lung (n = 26), and both (n = 12). Analyzing the results, we found that the patients with respiratory symptoms had a higher incidence of abnormal results of PFT and DTPA lung scans than the patients without respiratory symptoms (p < 0.05). Besides, we found that the DTPA lung scan was more sensitive than chest x-ray and PFT in detecting the lung injuries related to the consumption of S. androgynus (p < 0.05). Consuming S. androgynus can result in symptomatic or asymptomatic lung injuries, manifested as obstructive or restrictive ventilatory impairment, unhomogeneous radioaerosol distribution, and increased alveolar epithelial permeability. In addition, measurement of the 99mTc-DTPA clearance is the most sensitive test to detect the lung injuries caused by consuming S. androgynus.     

Study on antifertility effect of a novel LHRH antagonist in male rats

The diagnosis of pulmonary embolism is even in contemporary clinical practice problematical. Pulmonary angiography is used in our departments very little due to its invasive character. The method of choice for diagnosis remains therefore perfusion scintigraphy of the lungs, in this country frequently without ventilation scintigraphy as it is not available in the majority of our departments of nuclear medicine. In recent years in the diagnostic algorithms also assessment of D-dimers was started, i.e. assessment of products of fibrinolysis assessed by monoclonal antibodies. The authors tried to find out how many patients admitted to the medical department for diagnosis of pulmonary embolization may have a false positive diagnosis on the basis of pulmonary scintigraphy. During the period III/96 to V/96 a total of 18 patients from the medical clinic with suspected pulmonary embolism were examined where the value of D-dimers(latex test) was assessed and at the same time perfusion scintigraphy was performed. With regard to the highly negative predictive value of D-dimer assessment the authors focused their attention on patients with a suspect or positive lung scan (i.e. treated on account of pulmonary embolism) while D-dimers were negative. Of 13 patients with suspect or possible pulmonary embolism, as assessed by scintigraphy, four had negative dimers(30%). With regard to the 90% reported negative predictive value, based on the literature, thus three of these patients were unnecessarily admitted to hospital and treated. The authors assume that assessment of D-dimers should be part of the examination protocol due to its non-pretentious character and low price as compared with costs of hospitalization.     

Gallium-67 (Ga-67) scintigraphy in tuberculosis and Mycobacterium avium-M. intracellulare infections in patients with HIV infections

BACKGROUND: Diagnosis of mycobacterioses in HIV infected patients is sometimes difficult because of atypical findings. The aim of this study was to assess the utility of gallium scintigraphy in diagnosis of AIDS related mycobacterioses in patients with fever of unknown origin. PATIENTS AND METHODS: We retrospectively reviewed the scans of 220 HIV(+) patients with fever (176 males [80%] and 44 females) who were evaluated with conventional diagnostic procedures at least of a week before. RESULTS: Gallium scintigraphy was positive in 114 patients (51%) and negative in 106 (49%). Mycobacteria were isolated in 83 patients (38%), 75 of these patients (90%) had a positive scintigraphy (sensitivity 90%; specificity 71%). Positive predictive value was 66% and negative predictive value was 92%. Mycobacterium avium-M. intracellulare (MAI) and M. tuberculosis were diagnosed in 22 (29%) and 53 (71%) HIV(+) patients, respectively. Seventy one (94%) of 75 patients with mycobacterioses had gallium uptake in at least two localizations. CONCLUSIONS: 67Ga scintigraphy is very useful in HIV(+) patients with fever of unknown origin. A negative gallium scintigraphy makes unlikely the diagnosis of mycobacterioses.     

The utility of a somatostatin-type receptor binding peptide radiopharmaceutical (P829) in the evaluation of solitary pulmonary nodules

OBJECTIVE: Many neoplasms including small cell cancers more densely express somatostatin-type receptors or more avidly bind somatostatin than granulomatous and other nonmalignant processes. While non-small cell neoplasms of the lung have not yet been shown to demonstrate this receptor expression, previous studies have documented non-small cell lung cancer detection with somatostatin analog scintigraphy. This phenomenon can be conceivably exploited utilizing technetium Tc-99m P829 (P829), a unique low molecular weight somatostatin-type receptor binding polypeptide radiopharmaceutical. The objective of this study was to determine the ability of P829 scintigraphy to noninvasively differentiate malignant and nonmalignant solitary pulmonary nodules (SPNs). METHODS: The radiopharmaceutical technetium 99mTc-P829 was utilized for scintigraphy including single photon emission computed tomography. Thirty individuals with indeterminate SPNs of > or = 1 cm and significant risk factors for primary lung cancer were identified and underwent P829 scintigraphy. Tissue diagnosis was then established by transthoracic needle biopsy specimens. RESULTS: Fourteen subjects demonstrated abnormal P829 scans in the region of the radiographic abnormality. Twelve of this group had biopsy specimens revealing neoplasia. Two subjects with necrotizing granuloma on biopsy specimen had abnormal P829 scans in the region of the nodule. Sixteen subjects had no abnormal P829 tracer uptake in the region of the nodule. Fourteen subjects had benign diagnoses on biopsy specimens. One member of this group with a non-diagnostic biopsy specimen refused thoracotomy and remains radiographically stable at 24 months of follow-up. One subject with a squamous cell carcinoma demonstrated no P829 activity in the region of the nodule. The specificity of P829 scintigraphy based on transthoracic needle biopsy specimen was 88%. The sensitivity was 93%. P829 scintigraphy correctly identified or excluded malignancy in 27 of 30 subjects. CONCLUSIONS: P829 scintigraphy reliably identified or excluded malignancy in radiographically indeterminate solitary pulmonary nodules. The sensitivity and specificity compared favorably with the reported results of F-18 fluorodeoxyglucose positron emission tomographic imaging.     

Value of perfusion lung scan in the diagnosis of pulmonary embolism: results of the Prospective Investigative Study of Acute Pulmonary Embolism Diagnosis (PISA-PED)

To assess the value of perfusion lung scan in the diagnosis of pulmonary embolism, we prospectively evaluated 890 consecutive patients with suspected pulmonary embolism. Prior to lung scanning, each patient was assigned a clinical probability of pulmonary embolism (very likely, possible, unlikely). Perfusion scans were independently classified as follows: (1) normal, (2) near-normal, (3) abnormal compatible with pulmonary embolism (PE+: single or multiple wedge-shaped perfusion defects), or (4) abnormal not compatible with pulmonary embolism (PE-: perfusion defects other than wedge-shaped). The study design required pulmonary angiography and clinical and scintigraphic follow-up in all patients with abnormal scans. Of 890 scans, 220 were classified as normal/or near-normal and 670 as abnormal. A definitive diagnosis was established in 563 (84%) patients with abnormal scans. The overall prevalence of pulmonary embolism was 39%. Most patients with angiographically proven pulmonary embolism had PE+ scans (sensitivity: 92%). Conversely, most patients without emboli on angiography had PE- scans (specificity: 87%). A PE+ scan associated with a very likely or possible clinical presentation of pulmonary embolism had positive predictive values of 99 and 92%, respectively. A PE- scan paired with an unlikely clinical presentation had a negative predictive value of 97%. Clinical assessment combined with perfusion-scan evaluation established or excluded pulmonary embolism in the majority of patients with abnormal scans. Our data indicate that accurate diagnosis of pulmonary embolism is possible by perfusion scanning alone, without ventilation imaging. Combining perfusion scanning with clinical assessment helps to restrict the need for angiography to a minority of patients with suspected pulmonary embolism.     

Thermoregulatory responses of mesic and xeric rodent species to photoperiod manipulations

PURPOSE: To evaluate hypertrophied bronchial arteries on thin-section computed tomographic (CT) scans in patients with bronchiectasis by using CT angiographic correlation. MATERIALS AND METHODS: Spiral CT angiography was performed prospectively in 14 patients (eight men, six women; age range, 34-71 years) with bronchiectasis who were suspected of having bronchial arterial hypertrophy at thin-section CT (performed without contrast medium). The inclusion criteria were tubular (in six patients) or nodular (in 14 patients) areas of soft-tissue attenuation that had an appearance unlike that of lymph nodes at thin-section CT and that were within the mediastinum and around the central airway. These findings were subsequently correlated with the spiral CT angiographic findings. RESULTS: At comparative analysis of thin-section CT scans and CT angiograms, seven of the eight (88%) tubular lesions and 19 of the 36 (53%) nodular lesions in the mediastinal soft tissue were proved to be hypertrophied bronchial arteries. All of the six (100%) tubular and 19 of the 21 (90%) nodular lesions around the walls of the main (primary) and lobar bronchi were hypertrophied bronchial arteries. In eight (57%) patients, CT angiograms showed 11 intraluminal protrusions caused by hypertrophied bronchial arteries in the main bronchi, lobar bronchi, or both. CONCLUSION: Nodular and tubular structures in the mediastinum and around the central airway on thin-section CT scans in the patients with bronchiectasis are suggestive of hypertrophied bronchial arteries. Recognition of the hypertrophied bronchial artery can be critical for the bronchoscopist.     

Clinicians' interpretation of the indeterminate ventilation-perfusion scan report

Most patients with suspected pulmonary embolism are initially investigated by radio-nuclide ventilation-perfusion (VQ) scanning. Approximately 70% of VQ scans are "indeterminate". Further investigations should be considered in such patients in order to establish a definitive diagnosis. However, these investigations are rarely requested in patients with indeterminate scans in our institution. We therefore decided to review the casenotes of such patients to determine their subsequent management. Over a 9 month period, 131 (32%) out of a total of 413 consecutive VQ scans were reported as indeterminate. The casenotes of 111 of these patients (65 female, 46 male, mean age 65 years, range 17-91 years) were reviewed. 52 of the 111 patients (46%) were treated on clinical grounds without further investigation; 12 patients (11%) had further investigation; and in 39 of the cases (35%) the VQ scan report was misinterpreted. 20 (38%) of the 52 patients managed on clinical grounds were treated for pulmonary embolus with anticoagulation and 26 (50%) were not anticoagulated. Of the 12 patients who were investigated further, nine had lower limb Doppler ultrasound and three had contrast venography. No patients had pulmonary angiography. Of the 39 cases where the VQ report was misinterpreted, the result was misquoted in the casenotes of 37 (95%) as negative for PE and none of these patients were anticoagulated, and in two cases (5%) it was misquoted as positive for PE and anticoagulant therapy was instituted. The misunderstanding was observed in all clinical firms. Such misinterpretation may have significant implications, since 30-40% of patients with indeterminate scans may have had PE. Our findings suggest that clinicians need to be better informed of the significance of an indeterminate VQ scan result.     

Effects of arginine, growth hormone-releasing hormone (GHRH) and neostigmine administered singly or in paired combinations on growth hormone (GH) release in pigs

OBJECTIVE: A multicentre study was undertaken to determine the value of somatostatin receptor (sst) scintigraphy in predicting hormonal and visual responses to octreotide treatment in GH-secreting and non-functioning pituitary adenomas. SUBJECTS AND METHODS: Somatostatin receptor scintigraphy was performed in 48 patients (19 acromegaly, 29 non-functioning pituitary adenomas with ophthalmological defects). Results were expressed as an uptake index of the pituitary area. A threshold for positivity was determined in 23 subjects considered as controls. Thirty-five patients were treated for 1 month with octreotide (300 micrograms daily). The therapeutic response was assessed on GH and IGF-I suppression or evolution of the ophthalmological defects. The relationships between the somatostatin receptor scintigraphy result, the therapeutic effect of octreotide and in vitro studies performed in 12 tumours were studied. RESULTS: From the results of control subjects the uptake index threshold for positivity was 2. In patients, somatostatin receptor scintigraphy was positive in 64% and there was no relationship between uptake index and tumour size. In GH tumours, somatostatin receptor scintigraphy was positive in 68%; uptake index was related to octreotide-induced GH and IGF I suppression. The positive predictive value was 100% and the negative predictive value was 50%. In vitro studies showed detectable binding sites for somatostatin with sst2 and sst5 expression in the 4 GH tumours studied although somatostatin receptor scintigraphy was negative in 2 cases. In non-functioning pituitary adenomas somatostatin receptor scintigraphy was positive in 62%. Based on visual effects, the positive predictive value was 61% and the negative predictive value was 100%. A wide distribution of somatostatin binding sites was found in 8 non-functioning pituitary adenomas with expression of sst2 only. CONCLUSION: In the conditions of the study, in patients with acromegaly, positive somatostatin receptor scintigraphy predicts a hormonal response but the value of somatostatin receptor scintigraphy is limited by its low negative predictive value. In patients with non-functioning pituitary adenomas, negative somatostatin receptor scintigraphy predicts that there will be no visual improvement during octreotide treatment.     

The role of iodine-131 and thallium-201 imaging and serum thyroglobulin in the management of differentiated thyroid carcinoma

BACKGROUND: A prospective study was conducted to evaluate the use of iodine-131 sodium scintigraphy, thallium-201 chloride scintigraphy, and quantitative serum thyroglobulin estimation in the detection of differentiated thyroid carcinoma after thyroidectomy and iodine-131 sodium ablative therapy. METHODS: Thirty-one patients with a median age of 45.6 years (range, 20-73 years) were included in the study. After optimal endogenous thyroid-stimulating hormone stimulation (> 50 mU/ml), 53 pairs of iodine-131 and thallium-201 scans were performed. Concomitant serum thyroglobulin levels were available for 32 pairs of scans. The presence or absence of thyroid cancer was established by clinical, radiologic, and/or biopsy findings. RESULTS: The concordance between iodine-131 and thallium-201 scan findings in the presence of disease (25 scan sets) was 36%. The concordance in the absence of disease (28 scan sets) was 82%. Iodine-131 scanning was found to be significantly better (P < 0.05) than thallium-201 scanning, in terms of sensitivity (0.8 versus 0.6), specificity (0.96 versus 0.82), accuracy (0.89 versus 0.72), and the predictive value of a positive test (0.95 versus 0.75). The measurement of serum thyroglobulin had a low sensitivity (0.3) in the study but had a specificity of 1.0. CONCLUSION: It was concluded that iodine-131 sodium scintigraphy is superior to thallium-201 scintigraphy and serum thyroglobulin estimation for the detection of residual or metastatic differentiated thyroid carcinoma. However, the use of combined modalities provides a higher diagnostic yield. Thallium-201 scintigraphy was especially useful in cases in which iodine-131 scintigraphy was negative and quantitative thyroglobulin levels were elevated.     

Findings at mammographic screening on only one standard projection: outcomes analysis

PURPOSE: To compare thallium-201 scintigraphy with gallium-67 scintigraphy in the detection of residual or recurrent mediastinal Hodgkin disease after treatment. MATERIALS AND METHODS: The authors performed planar Ga-67 and Tl-201 scintigraphy in 39 patients aged 7-18 years (27 with mediastinal primary disease) after primary treatment. These scans and those in a control group of 14 patients with newly diagnosed known mediastinal Hodgkin disease were evaluated independently by two radiologists for abnormal mediastinal activity. Results were compared with chest computed tomographic (CT) findings and with the clinical criteria of disease status. Interobserver agreement and consensus agreement on gallium and thallium scan findings were evaluated with the kappa statistic, and the specificity of the two imaging methods was analyzed. RESULTS: All study patients were judged to be free of mediastinal disease with CT and the clinical criteria. Interobserver agreement on findings in the treated and control patients was stronger with gallium scintigraphy (kappa +/- SD = 0.956 +/- 0.044) than with thallium scintigraphy (kappa = 0.638 +/- 0.110). Specificity of ratings based on thallium (85% +/- 6) and gallium (90% +/- 5) scintigraphic findings of mediastinal disease did not differ significantly (P = .48). Specificity improved when the results of the two examinations were combined (97% +/- 2). CONCLUSION: Thallium scintigraphy can help to predict the absence of mediastinal Hodgkin disease after treatment.     

Sensitivity and specificity of a rapid whole-blood assay for D-dimer in the diagnosis of pulmonary embolism

BACKGROUND: Patients with suspected pulmonary embolism often have nondiagnostic lung scans and may present in circumstances where lung scanning is unavailable. Levels of D-dimer, a fibrin-specific product, are increased in patients with acute thrombosis; this may simplify the diagnosis of pulmonary embolism. OBJECTIVE: To determine the sensitivity and specificity of a whole-blood D-dimer assay in patients with suspected pulmonary embolism and in subgroups of patients with low pretest probability of pulmonary embolism or nondiagnostic lung scans. DESIGN: Prospective cohort. SETTING: Four tertiary care hospitals. PATIENTS: 1177 consecutive patients with suspected pulmonary embolism. MEASUREMENTS: All patients underwent an assessment of pretest probability by use of a standardized clinical model, a D-dimer assay, ventilation-perfusion lung scanning, and bilateral compression ultrasonography. Patients in whom pulmonary embolism was not initially diagnosed were followed for 3 months. Accordingly, patients were categorized as positive or negative for pulmonary embolism. RESULTS: Of the 1177 patients, 197 (17%) were classified as positive for pulmonary embolism. Overall, the D-dimer assay showed a sensitivity of 84.8% and a specificity of 68.4%. In 703 patients (3.4%) with a low pretest probability of pulmonary embolism, the likelihood ratio associated with a negative D-dimer test result was 0.27, resulting in a posterior probability of 1.0% (95% CI, 0.3% to 2.2%). In 698 patients with nondiagnostic lung scans (previous probability, 7.4%), the likelihood ratio associated with a negative D-dimer test result was 0.36, resulting in a posterior probability of 2.8% (CI, 1.4% to 4.8%). CONCLUSIONS: A normal D-dimer test result is useful in excluding pulmonary embolism in patients with a low pretest probability of pulmonary embolism or a nondiagnostic lung scan.