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Biomedical subjects

D R Neumann

Publications and source records attributed to D R Neumann.

30 records · Page 2Linked to original sources
PubMed1993

Pulmonary embolism: increased ventilation in areas of decreased perfusion.

An abnormal finding that is considered characteristic of large or extensive pulmonary embolism has been observed on ventilation-perfusion (V-P) lung scans. This observation is a regional area of increased ventilation radioactivity in the embolized region of the lung that is more than the normal ventilation radioactivity in the adjacent or contralateral normally perfused lung. It has been designated the "enhanced V-P mismatch sign." This sign was noted in 15 cases among approximately 700 routine V-P lung scans interpreted by a nuclear radiologist. Of these, large or extensive emboli were confirmed in only 10 cases, nine by means of angiography and one by means of autopsy studies. The remaining five cases demonstrated clinical correlation only and are not included in this report. Of the 10 confirmed cases with enhanced V-P mismatch sign, increased ventilation radioactivity involved unilateral lung distribution in five and zonal or lobar distribution in five. The Westermark sign was seen in only seven of the 10 cases. It is hoped that this observation will prove useful in the diagnosis of large or extensive pulmonary emboli.

Adult↗
PubMed1993

Clinical outcome of cardiac patients with negative thallium-201 SPECT and positive rubidium-82 PET myocardial perfusion imaging.

In a previous comparison of 202 consecutive patients who underwent myocardial perfusion imaging with both 201Tl SPECT and 82Rb PET, 27 patients were identified as having true-positive 82Rb images, but false-negative 201Tl images. The purpose of this report is to determine the effect of correct image interpretation of coronary artery disease on the final management of those patients and compare it to the previous management scheme wherein a negative image was usually accepted as the end point unless clinical symptoms dictated otherwise. A follow-up study of the clinical course and outcome of these studies showed that 63% (17/27) of the patients with a true-positive 82Rb PET image were recommended for revascularization procedures. It is doubtful that this majority of patients would have received either surgical or interventional management based on the false-negative 201Tl SPECT procedure alone.

Angioplasty, Balloon, Coronary↗
PubMed1992

Myocardial perfusion imaging in the diagnosis of coronary artery disease.

The role of myocardial perfusion imaging has been extended from diagnosis to management and prognosis in patients with coronary artery disease. Great emphasis has been placed on improving the accuracy of the test to better define perfusion, viability, and the extent of damage of the myocardium. To achieve this goal, investigators have focused on several areas including imaging technique, in which the accuracy of single-photon emission CT has been compared with that of positron emission tomography; radiopharmaceuticals, in which 201Tl has been compared with 99mTc-sestamibi and 99mTc-teboroxime; stress modalities, in which dipyridamole and adenosine stress have been compared with exercise; myocardial viability, as determined by delayed and reinjection 201Tl imaging or by measurement of cellular integrity using 82Rb compared with 18fluorodeoxyglucose metabolic PET imaging; and assessment of myocardial salvage and prognosis by exercise or dipyridamole 201Tl imaging in acute myocardial infarction.

Adenosine↗
PubMed1990

Use of the 82Sr/82Rb generator in clinical PET studies.

The use of the 82Sr/82Rb generator in clinical positron emission tomography (PET) studies of myocardial perfusion has been described. An infusion pump is used to deliver the short-lived 82Rb from the generator to the patient. Various characteristics of the generator and the infusion system are described. The 82Rb yield was 69.8 +/- 13.3% and the 82Sr breakthrough was always less than the limit of 0.02 microCi/mCi 82Rb. The yield of 82Rb increased with the flow rate and the potency of the generator. Patients with coronary artery disease were studied for myocardial perfusion abnormalities by the 82Rb PET technique and images of excellent diagnostic quality were obtained.

Coronary Circulation↗
PubMed1990

A prospective comparison of rubidium-82 PET and thallium-201 SPECT myocardial perfusion imaging utilizing a single dipyridamole stress in the diagnosis of coronary artery disease.

The purpose of the present study is to prospectively compare myocardial perfusion imaging with rubidium-82 (82Rb) by positron emission tomography (PET) with thallium-201 (201Tl) imaging by single-photon emission tomography (SPECT) by recording both studies with a single dipyridamole handgrip stress, and reading both sets of images with the same display technique. In a series of 202 patients with previous coronary arteriography, the sensitivity, specificity, and accuracy of 82Rb PET were 93%, 78%, and 90% and for 201Tl SPECT 76%, 80%, and 77%, respectively. When 70 patients with previous therapeutic interventions were excluded, the remaining 132 patients showed a sensitivity, specificity, and accuracy of 95%, 82% and 92% for 82Rb PET and 79%, 76%, and 78% for 201Tl SPECT. The improved contrast resolution of PET resulted in markedly superior images and a more confident identification of defects.

Coronary Circulation↗
PubMedDate not supplied

The incidence of scintigraphically viable and nonviable tissue by rubidium-82 and fluorine-18-fluorodeoxyglucose positron emission tomographic imaging in patients with prior infarction and left ventricular dysfunction.

BACKGROUND: Although reversible perfusion defects, perfusion-metabolism mismatch and match patterns are important for differentiating viable from nonviable myocardium, the frequency of these scintigraphic patterns has not been reported. The study objective was to establish the incidence of these scintigraphic patterns to estimate the clinical need for metabolic positron emission tomography for evaluating tissue viability in patients with prior myocardial infarction (MI). METHODS AND RESULTS: 82Rb perfusion images were interpreted to identify reversible or irreversible defects, followed by determination of their 18F-fluorodeoxyglucose (18F-FDG) uptake pattern. In 155 patients with prior MI, analysis of 613 abnormal segments showed reversible perfusion defects in 13%. The 87% irreversible defects, 18% showed perfusion-metabolism mismatch, whereas 69% showed the match pattern. Reversible perfusion defects and perfusion-metabolism mismatches were noted in 20% (31/155) and 29% (45/155) of patients, respectively, whereas the match pattern was noted in 51% (79/155) of patients. CONCLUSION: Irreversible perfusion defects were common in our patients with prior MI, and distinction between viable and nonviable tissue was not possible by perfusion imaging alone. The identification of hibernating myocardium was possible only with the additional 18F-FDG imaging in about one third of patients. This indicates a significant clinical demand for 18F-FDG imaging that identifies patients who will benefit from revascularization.

Adult↗
PubMedDate not supplied

Parathyroid adenoma localization by PET FDG.

A patient with primary hyperparathyroidism was examined with positron emission tomography using [18F]-2-fluorodeoxyglucose. The radioactive tracer accumulated in a cervical mass that proved to be a parathyroid adenoma resulting in the correct preoperative localization of the parathyroid tumor.

Adenoma↗
PubMedDate not supplied

Regional body FDG-PET in postoperative recurrent hyperparathyroidism.

PURPOSE: The use of preoperative imaging studies in patients with persistent or recurrent hyperparathyroidism after initial operation is generally accepted to improve the success rate and minimize the morbidity from reoperative surgery. The purpose of this study was to define the performance of FDG-PET for the localization of hyperfunctioning parathyroid tissue prior to reoperation. METHOD: Twenty patients with biochemical evidence of recurrent or persistent hyperparathyroidism following previous neck surgery were investigated. Regional body PET imaging of the neck and upper chest (axial field of view 27.5 cm) was acquired 45 min after 5-10 mCi FDG was given intravenously. RESULTS: Subsequent surgery revealed solitary parathyroid adenomas in 14 patients, seven hyperplastic glands in 2 patients, and parathyroid carcinoma in 1 patients. FDG-PET correctly identified 79% (11/14) of the parathyroid adenomas, 29% (2/7) of the hyperplastic glands, and the parathyroid carcinoma. FDG-PET was negative in 79% (30/38) of the surgically identified normal parathyroid glands. Eight false-positive findings led to a positive predictive value of 64%. CONCLUSION: These preliminary data suggest that regional body FDG-PET is a promising procedure in the evaluation of patients with persistent or recurrent postoperative hyperparathyroidism.

Adenoma↗