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Biomedical subjects

P F Sharp

Publications and source records attributed to P F Sharp.

At least 73 records · Page 4Linked to original sources
PubMed1988

Technetium-99m HMPAO imaging in patients with basal ganglia disease.

Technetium 99m hexamethylpropylene-amine oxime (HMPAO) is trapped by cerebral grey matter and the basal ganglia on its first pass through the brain. To assess its potential for studying patients with diseases of the basal ganglia, a study of 15 normal volunteers and 32 patients with known or suspected basal ganglia disease have been investigated. Sixteen patients with idiopathic Parkinson's disease showed no abnormality of the basal ganglia and varying degrees of cerebral underperfusion consistent with their intellectual status. Eight patients with Huntington's chorea showed a characteristic pattern of reduced or absent caudate nucleus uptake. Patients with diseases affecting the basal ganglia, such as Fahr's disease, Wilson's disease and hemibalismus had varying degrees of basal ganglia underperfusion as demonstrated by an HMPAO scan. We believe that this new radiopharmaceutical for the demonstration of cerebral blood flow shows significant potential for the diagnosis and management of patients with basal ganglia disease.

Adult↗
PubMed1988

Effective use of physics services in the NHS.

The work of medical physics departments in the national health service encompasses physics, electronic and mechanical engineering, computing, mathematics, biophysics and bioengineering. In some cases, there are separate bioengineering departments, but for the purpose of this article, no distinction is made.

Biomedical Engineering↗
PubMed1987

Nuclear magnetic resonance imaging and single photon emission tomography with radio-iodine labelled compounds in the diagnosis of dementia.

White matter lesions and T1 changes were identified using NMR and then compared between groups of patients suffering from dementia of the Alzheimer type (DAT), Multiple infarct dementia (MID) and normal controls. All DAT and MID patients were also imaged with a gamma camera using 123Iodo-n-isopropyl-amphetamine, a radiopharmaceutical whose uptake in the brain follows the regional blood flow. While NMR was not able to differentiate between DAT and MID, 19 out of 21 DAT patients compared to four out of 18 MID patients showed bilateral parietal lesions on IMP scans.

Adult↗
PubMed1986

Technetium-99m HM-PAO stereoisomers as potential agents for imaging regional cerebral blood flow: human volunteer studies.

A total of nine normal volunteer subjects were studied with three forms of [99mTc] hexamethylpropyleneamineoxime (HM-PAO), a potential cerebral blood flow imaging agent. One, the d,l isomer, showed 4.1% uptake in the brain which remained constant over 8 hr. There was good differentiation between uptake in gray and white matter on tomographic slices. We propose that this agent may allow regional cerebral blood flow imaging to be performed on a routine basis.

Adult↗
PubMed1985

Comparison of quantitative and visual detection of new focal bone lesions.

A comparison is made between the sensitivity of detection of focal abnormalities in radionuclide bone images by visual examination and by using simple quantification. The quantitative method calculates the ratio of radiopharmaceutical uptake in a region of interest drawn around a lesion to that in an area of normal bone. Quantification is found to be far more sensitive than visual examination in detecting focal metastases. The use of "baseline" images improved the precision of quantitation of rib lesions, but appeared not to alter the sensitivity of visual detection. This method of quantification is therefore limited more by the inability of observers to notice suspicious areas to which it should be applied than by inaccuracies inherent in the method itself. Further work should concentrate more on image enhancement than on improving quantitative techniques.

Bone Neoplasms↗
PubMed1985

A simple filtering routine for radionuclide bone images.

The evaluation is carried out of a simple filtering routine for improving the detectability of low contrast lesions in bone scans. With this routine, the unprocessed image is displayed together with three filtered versions, the final decision on the presence of abnormalities being made by comparing the four images. Emphasis is placed on producing a routine which is quick in implementation and, therefore, only small filter arrays are used. Using a routine consisting of a low-pass, a median, and a differential filter, 73% more lesions are detected when the filtered images are also used. The whole routine takes less than 1 min to run.

Bone and Bones↗
PubMed1983

Relationship between objective and subjective assessment of gamma camera image sharpness.

In order to relate the performance of the human observer to the objective specifications of a gamma camera system, images of a test object were taken under various conditions that could be expected to cause changes in resolution. Observers were asked to put the images in the order of increasing/decreasing sharpness. For the same physical conditions, objective measurements were made from which the resolution parameters FWHM and FWTM could be derived. By looking for significant differences in ordering of the images, it was possible to show that, within the limitations of the specific system investigated, a fractional change in FWHM of about 10% caused a significant change in image quality. Further experiments to test the universality of this figure are suggested.

Humans↗
PubMed1983

Frequency of venous thrombosis in patients with an exacerbation of chronic obstructive lung disease.

The presence or absence of venous thrombosis was determined in 29 patients with an acute exacerbation of chronic obstructive lung disease by the technique of autologous platelet labelling with indium-111. Deep venous thrombosis was diagnosed in 13 patients and in nine of these patients thrombosis was located proximal to the knee--that is, in areas associated with an appreciable risk of pulmonary embolism. One patient died; pulmonary emboli were found at postmortem examination. The incidence of venous thrombosis seen in this study is high enough to suggest that these patients may benefit from prophylactic antithrombotic treatment.

Aged↗
PubMed1983

Radionuclide image minification can compensate for coarse digitization: concise communication.

Although it is common practice to digitize radionuclide images onto the finest matrix available, their low count densities and poor spatial resolution suggest that quite large pixels should be adequate. Observers find these large pixels visually obtrusive, but minification of the image can reduce this effect. Experiments reported here have investigated how minification (achieved by increasing viewing distance) affects the perceived quality of images digitized onto different sized matrices. Observers' subjective preference for different pixel sizes was measured at various viewing distances using clinical bone images as test patterns. An objective measure of image quality was made by comparing the detectability of computer-generated focal areas of increased activity both in simple noisy backgrounds and in clinical bone images. The results show that a 128 X 128 matrix is adequate when the image is 8 cm2 and is viewed from 1 and 2 m. A finer matrix failed to produce better results.

Bone and Bones↗
PubMed1982

Hepatobiliary imaging using Tc-pyridoxylideneglutamate in the diagnosis of obstructive jaundice.

In 77 of 114 consecutive patients with suspected hepatobiliary disease undergoing cholescintigraphy a firm clinical or operative diagnosis was possible. These patients were classified as normal, or as having extra-hepatic biliary obstruction (partial or complete) or hepatocellular disease. On a double-blind basis cholescintigraphy correctly interpreted 18 of 20 (90%) normal controls, 12 of 14 (86%) of those with partial obstruction, 16 of 16 (100%) of those with complete obstruction and 23 of 27 (85%) of those with hepatocellular disease giving an overall diagnostic accuracy of 69 of 77 (90%). There were no complications or toxic reactions. Ninety-three percent of patients with biliary obstruction (sensitivity) and 87% of those without biliary obstruction (specificity) were correctly diagnosed. Cholescintigraphy is a non-invasive, cheap and reliable investigation which can be used in the presence of icterus to discriminate between patients with and without extra-hepatic biliary obstruction. In contrast to grey scale ultrasonography the production and interpretation of scans are simple. Moreover cholescintigraphy adds a functional element to the investigation of liver disease.

Cholestasis↗