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Biomedical subjects

P F Sharp

Publications and source records attributed to P F Sharp.

85 records · Page 5Linked to original sources
PubMed1982

The influence of picture element size on the quality of clinical radionuclide images.

The effect of picture element (pixel) size on image quality is investigated. Asked simply to state their preference for clinical images displayed with different pixel sizes, observers preferred those with the smallest pixel. Specific perceptual tasks, however, such as abnormality detection, are found to be insensitive to changes in pixel size up to a limit. Interpolation is found to have no effect on perceptual tasks, but 'random interpolation' produced a more pleasing image than simple linear interpolation.

Humans↗
PubMed1981

Intravenous radionuclide cystography for the detection of vesicorenal reflux.

Intravenous radionuclide cystography using a single intravenous injection of 99mtechnetium diethylenetriaminepentaacetic acid, provides information on individual kidney function, coarse anatomy and vesicorenal reflux. This study investigates the effectiveness of intravenous radionuclide cystography in detecting reflux. In 58 children intravenous radionuclide cystography detected 53 ureters with reflux compared to 32 detected by voiding cystography. This difference was investigated further with patients in whom other test suggested reflux. While there was no statistically significant difference for patients having pyelonephritis or hydronephrosis, intravenous radionuclide cystography detected significantly more ureters with reflux in patients with abnormal ureteral orifices or infected urine and, therefore, predisposed to reflux. Intravenous radionuclide cystography is a more comprehensive and sensitive test for vesicorenal reflux than voiding cystography.

Adolescent↗
PubMed1981

Reproducibility of gamma camera data.

The increasing use of quantification in the interpretation of nuclear medicine images requires a knowledge of the errors associated with the estimation of the activity in a volume of interest from the recorded count rate data. Using sources of known cross-sectional area from 1 to 25 cm2, errors caused by variations in the count rate, day of measurement, source position in the camera field of view, and source size are evaluated. The effect of source depth in tissue-equivalent (TE) medium on the reproducibility of the data is also investigated. For a given source size at a known depth, variations in camera response lead to an error (SD) of a least 6% that increases as either the source size or the depth of the source in TE medium is increased. Failure to estimate accurately the true depth of the organ can also be a major source of error. The use of two conventional types of flood correction technique ('count-skipping' and matrix division) is found to increase the error only in the case of the smallest source.

Models, Structural↗
PubMed1980

"Stasis"--a test for vesico-ureteric orifice competence in children with reflux.

Intravenous radionuclide cystography (IVRNC) with one injection on 99m-Tc-DTPA measures renal function and detects vesico-renal reflux [1, 2, 3]. This paper describes a possible means of detecting incompetent ureteric orifices during IVRNC examinations. In some patients a hold-up of material in the renal areas (stasis) was observed which suddenly cleared at micturition. A prospective study of 58 patients who had IVRNC and cystoscopy within 28 days of each other revealed that 76.3% had anatomically abnormal ureteric orifices on the same side as the stasis. This contrasted with only 12.8% of abnormal uretic orifices found in patients not showing stasis (p less than 0.005). As incompetent ureteric orifices are recognised as the major aetiological factor in vesico-renal reflux [4, 5, 6] this additional information gained at IVRNC could be of clinical use and perhaps avoid some cystoscopies.

Child↗
PubMedDate not supplied

Differential diagnosis in dementia using the cerebral blood flow agent 99mTc HM-PAO: a SPECT study.

One of the potential clinical uses of the new cerebral blood flow agent 99mTc-hexamethylpropyleneamineoxime (HM-PAO) is the investigation of dementia, in particular to differentiate between dementia of the Alzheimer type (DAT) and multiinfarct dementia (MID). In this study 27 patients, 17 with DAT and 10 with MID, and three normal volunteers were imaged both with single photon emission CT and magnetic resonance. The HM-PAO perfusion deficits were much more common in the DAT group than in the MID group, especially in the temporoparietooccipital (TPO) regions. The two groups of patients were found to be significantly different (p less than 0.02), as regards the frequency of occurrence of bilateral TPO perfusion deficits. Four of the 17 DAT patients did not have bilateral TPO deficits but these included the three least impaired patients as assessed by psychometric testing.

Aged↗