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Biomedical subjects

G Coates

Publications and source records attributed to G Coates.

122 records · Page 7Linked to original sources
PubMed1974

Postoperative assessment of cerebral neoplasms: the need for an early brain scan.

Brain scans were performed on 40 patients who had had craniotomies for nonmalignant disease during the preceding 11 years. A significant decrease in radioactivity at the craniotomy site with time was found, and in nine patients studied five years post craniotomy there was no activity at all. Because of the frequent difficulty in interpreting the postcraniotomy brain scan when searching for recurrent tumours, it is recommended that baseline scans be obtained a few months after the operation to allow comparison of increased radioactivity at the craniotomy site with what may be seen on future brain scans.

Brain Neoplasms↗
PubMed1973

Measurement of the rate of stomach emptying using Indium-113m and a 10-crystal rectilinear scanner.

Accurate reproducible measurements of the rate of gastric emptying have only been possible since the advent of external radionuclide detection techniques. Indium-113m and a 10-crystal rectilinear scanner have been employed to measure stomach emptying rates. The technique is simple, the results reproducible and it has proved ideal for assessing the results of drug therapy in patients with gastric retention. In the normal individual the T50% was 42 to 95 minutes, and the relationship between counts and time was, to first approximation, a linear function.

Adult↗
PubMedDate not supplied

Aerosol delivery to the rabbit lung with an infant ventilator.

Little is known about delivery of aerosolized medications to infants undergoing assisted positive pressure ventilation. To assess delivery of medications to the lung with an infant ventilator (Bournes LS104), 27 experiments were performed on anesthetized adult rabbits. Lung deposition was determined by using aerosol radiolabeled with 99m technetium sulfur colloid. Initially a traditional nebulizer was studied and very inefficient delivery to the lung was observed (0.19 +/- 0.10 SD% of the initial nebulizer dose). Subsequent experiments using a nebulizer that generates submicronic aerosol particles, at equivalent aerosol output, achieved a highly significant increase in delivery (1.96 +/- 1.19 SD%, P less than 0.001). Our experiments demonstrated that modifications to to traditional nebulizer systems can enhance delivery of aerosolized medication to the lungs of rabbits.

Aerosols↗
PubMedDate not supplied

An analysis of factors which influence the local accumulation of bone-seeking radiopharmaceuticals.

A thoretical consideration of the factors which influence the accumulation of radiopharmaceuticals in bone is presented. The avidity with which 99mTc-Sn-pyrophosphate and 18F fluoride are adsorbed by bone crystals has been measured in vitro and the efficiency with which these radiopharmaceuticals are extracted by normal bone has been measured in vivo. It is postulated that alterations in the capillary permeability in the region of a bone lesion greatly influence the target to background ratio that can be obtained with bone seeking radiopharmaceuticals. Quantitiated gamma camera studies in man are presented in support of this hypothesis.

Animals↗
PubMedDate not supplied

The influence of certain physical and physiological factors on the in vivo measurement of lung density.

The effects of multiple photon scattering and the assumption of infinitesimal beam geometry on the results obtained with a clinical lung densitometer were investigated. In phantom materials, it was possible to account almost completely for the multiple scatter contribution by measurement of transmission for the 170Tm source. A theoretical analysis based on a simplified model showed that the influence of finite geometry was small. Measurements in six normal volunteers showed that lung density is a function of the fractional air content of the lung. To relate density to fractional water content of the lung, measurements must be made at a fixed lung volume. The height in the lung at which measurements are made appears to be unimportant. The results of these experiments enable predictions to be made concerning the clinical usefulness of lung density measurements.

Animals↗
PubMedDate not supplied

Imaging features of primary and recurrent esophageal cancer at FDG PET.

Because of the poor prognosis for patients with esophageal cancer and the risks associated with surgical intervention, accurate staging is essential for optimal treatment planning. Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) is a useful adjunct to more conventional imaging modalities in this setting. FDG PET is not an appropriate first-line diagnostic procedure in the detection of esophageal cancer and is not helpful in detecting local invasion by the primary tumor, and further studies are required to determine its efficacy in the detection of local nodal metastases. However, FDG PET is superior to anatomic imaging modalities in the ability to detect distant metastases. Metastases to the liver, lungs, and skeleton can readily be identified at FDG PET. In addition, FDG PET has proved valuable in determining the resectability of disease and allows scanning of a larger volume than is possible with computed tomography. Recurrent disease is readily diagnosed and differentiated from scar tissue with FDG PET. In addition, FDG PET may play a valuable role in the follow-up of patients who undergo chemotherapy and radiation therapy, allowing early changes in treatment for unresponsive tumors. The management of most patients with esophageal cancer can be improved with use of FDG PET.

Adenocarcinoma↗
PubMedDate not supplied

Emerging role of PET in the diagnosis and staging of lung cancer.

Positron emission tomography (PET) with 18F-fluoro-2-deoxyglucose (FDG) has recently emerged as a practical and useful imaging modality in patients with lung cancer. Malignant tumours demonstrate increased uptake of FDG, a positron-emitting radiopharmaceutical. This increased FDG uptake in tumours can be seen using PET. FDG PET has much higher accuracy than other imaging modalities for the differentiation of benign and malignant lung nodules. The sensitivity of PET is 96% and the specificity 77% for diagnosing malignant nodules. PET is also more accurate than computed tomography (CT) for staging mediastinal nodal involvement (sensitivity 89%, specificity 94%). While CT relies on an arbitrary anatomical cutoff of 1 cm to diagnose malignant nodes, which may simply be enlarged due to inflammation, PET can accurately diagnose metastases in nodes smaller than 1 cm. Several studies have shown significantly better staging of distant metastases with FDG PET than with traditional techniques such as bone scanning. Differentiation of recurrent disease from scar tissue in the postoperative patient is often difficult with CT or magnetic resonance imaging. The low uptake of FDG in scar tissue allows reliable differentiation between scar tissue and a recurring tumour with PET. Early studies suggest a promising role for PET in the evaluation of response to chemotherapy. This may allow treatment to be changed after only one course of chemotherapy, instead of waiting for anatomical disease progression to become obvious clinically or with CT. Finally, significant improvements in cost effectiveness have been demonstrated when FDG PET is added to the preoperative work-up of patients with lung cancer.

Bone Neoplasms↗
PubMedDate not supplied

Vidarkliniken.

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Color↗
PubMedDate not supplied

Recurrent nerve palsy due to parathyroid cyst.

Cysts of the parathyroid gland are uncommon neck masses and difficult to diagnose. They can cause symptoms by endocrinological function or by pressure on surrounding structures. A case of recurrent nerve palsy due to a parathyroid cyst is presented. Aspiration of parathyroid cysts can be diagnostic and therapeutic in some cases.

Cranial Nerve Diseases↗