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T K Hames

Publications and source records attributed to T K Hames.

28 records · Page 2Linked to original sources
PubMed1983

Application of statistical techniques to data obtained from Doppler ultrasound examination of the extracranial arteries.

Techniques of increasing sophistication are being used to analyse the data obtained from continuous wave Doppler Ultrasound examination of patients with suspected arterial disease in the extracranial circulation. This study was carried out in order to compare the results of using relatively simple parameters such as the A/B ratio and the Index of Circulatory Resistance, ICR, and more recent techniques such as Principal Component Analysis on the changes apparent in the common carotid arterial waveform, particularly in the presence of disease in the internal carotid artery. This information was obtained from patients undergoing angiography so that the Doppler ultrasound results could be compared directly with an invasive assessment of the arteries under study. The signals obtained were processed off line using a Kay Sonograph Spectrum Analyser. The resulting maximum frequency envelope was further processed using a statistics package on a 2970 ICL computer. The A/B and ICR values were calculated manually. The preliminary results, calculated from 105 comparisons between Doppler ultrasound and angiography, suggest that techniques, such as Principal Components Analysis, are best able to cope with the waveform changes obtained in this study.

Adult↗
PubMed1982

Disseminated malignant phaeochromocytoma: localisation with iodine-131-labelled meta-iodobenzylguanidine.

Meta-iodobenzylguanidine, a guanethidine analogue, is a newly synthesised substance capable of imaging the adrenal medulla. In a woman in whom phaeochromocytoma has been diagnosed iodine-131-labelled metaiodobenzylguanidine was given intravenously; gamma-camera images showed bilateral adrenal tumours and uptake corresponding to bone and liver metastases. 131I-meta-iodobenzylguanidine is effective in localising phaeochromocytomas, and the technique is safe, specific, and non-invasive.

3-Iodobenzylguanidine↗
PubMed1982

The electrocardiographic and anticholinergic effects of trazodone and imipramine in man.

The electrocardiographic and anticholinergic effects of trazodone (150 mg) and imipramine (75 mg) were investigated in 8 healthy volunteers. Both agents increased the QTc interval and decreased T wave height, but the effects occurred earlier with trazodone (from 30 min onwards) than with imipramine (150 and 180 min after dosing). Both drugs decreased heart rate, imipramine at 30 and 60 min and trazodone at 90 min. After 120 min, heart rate began to increase with imipramine an effect which was not seen with trazodone. Salivary volume was significantly decreased by imipramine at 120 and 180 min whereas trazodone did not influence salivary volume. Plasma levels of trazodone and imipramine were significantly related to the decrease in T wave amplitude. The increase in QTc interval correlated significantly with the plasma level of imipramine. These results suggest that trazodone, like the tricyclic antidepressants prolongs ventricular repolarization; but, in contrast to imipramine, it does not have anticholinergic activity.

Adult↗
PubMed1982

Hemodynamic responses of trazodone and imipramine.

The hemodynamic effects of trazodone (150 mg) and imipramine (75 mg) were examined in eight healthy subjects. Trazodone significantly increased left ventricular ejection time 1 (LVETI), but decreased both preejection period (PEP) and PEP/LVET ratio. It also decreased heart rate and systolic and diastolic blood pressure at 90 min after dosing. Imipramine initially increased total electromechanical systole I (QS2I) and PEP (30 min, P less than 0.01), but at 150 and 180 min after dosing QS2I was significantly lower. Imipramine increased diastolic blood pressure at 30 min (P less than 0.05) and increased systolic blood pressure between 90 and 180 min (P less than 0.05). At 30 and 60 min heart rate was significantly depressed by imipramine. There were no significant changes in the values of stroke volume and cardiac output. These results suggest that trazodone has its major effect on the circulation through its alpha-receptor blocking activity, whereas the effects of imipramine are probably mediated through its ability to block reuptake of norepinephrine.

Adult↗
PubMed1982

Detection of arterial dilatation in the distal aorta--lower limb arteries using continuous wave Doppler ultrasound.

Continuous wave Doppler ultrasound techniques were used to obtain signals from the common femoral, popliteal, posterior tibial and dorsalis pedis arterial sites and the ankle systolic pressure indices in 54 patients with arteriographic, ultrasound "B"-Scan or surgical confirmation of arterial dilatation. The Doppler-shifted signals were spectrum-analysed and processed using a maximum frequency detector. The maximum frequency envelopes were examined retrospectively to determine whether there were any characteristics of the signals which could be used as diagnostic indicators of arterial dilatation. Ankle systolic pressure indices (ASPI), pulsatility index (PI), and delta, derived from the Laplacian transform method, were used in an attempt to quantify any changes produced by dilatation. The results indicate that characteristic and distinctive maximum frequency envelope signatures can be identified with arterial dilatation but that parameters such as ASPI and PI cannot distinguish these changes from the normal state and the Laplacian transform parameter "delta" places the dilatation cases in the minor stenosis category. However, generalised dilatation can be detected with a sensitivity of 85% if pattern recognition techniques are used.

Aged↗
PubMedDate not supplied

The accuracy of duplex scanning in the evaluation of early carotid disease.

The accuracy of duplex scanning in 69 comparisons with biplanar angiography in the detection of early carotid disease has been assessed. The various criteria reported for the categorisation of less than 50% disease have been critically analysed. As part of the study, 50 internal carotid arteries of 25 young, presumed normal medical students of mean age 20 years have been examined. The results suggest that duplex scanning has the ability to grade less than 50% carotid disease into normal, 1-24% and 25-49% stenosis categories. The most sensitive indicator of early disease is obtained from the real-time B-scan. The waveform changes of the maximum frequency envelope were more sensitive than spectral broadening except where full spectral broadening was present. For confident assessment, the real-time B-scan and pulsed Doppler must always be used in conjunction.

Adult↗
PubMedDate not supplied

The validation of duplex scanning and continuous wave Doppler imaging: a comparison with conventional angiography.

Colour-coded continuous wave (CW) Doppler imaging and duplex scanning have been assessed prospectively in comparison with biplanar angiography for their accuracy in detecting significant arterial disease in the extracranial circulation. Of 96 comparisons with biplanar angiography, the sensitivity of Doppler imaging was 90% and specificity 98% in the detection of greater than 50% internal carotid stenosis and 86 and 100%, respectively, in the diagnosis of internal carotid occlusion. Of 85 comparisons with biplanar angiography, the sensitivity of duplex scanning was 93% and specificity 98% in the detection of greater than 50% internal carotid stenosis and 92 and 100%, respectively, in the diagnosis of internal carotid occlusion. The value of the peak systolic Doppler shift frequency of the internal carotid artery signal has proved to be the most reliable indicator of greater than 50% stenosis and is utilised in conjunction with a periorbital examination. It is concluded that both Doppler imaging and duplex scanning are effective screening techniques for the presence of significant (greater than 50%) internal carotid artery disease.

Adolescent↗
PubMedDate not supplied

Characterisation of carotid artery disease: comparison of duplex scanning with histology.

The ability of duplex scanning to characterise the component tissue of atheromatous lesions of the internal carotid artery and to detect ulceration has been examined in a histological study of 42 carotid endarterectomy specimens. The results suggest that the only component of atheromatous lesions of the internal carotid artery which can be characterised from the B-scan is calcification. The presence of ulceration, intraluminal and intramural thrombus, fibrous intimal thickening and necrosis are not related to the echogenic appearance of internal carotid stenoses and may not be detected reliably. B-mode imaging alone cannot reliably grade greater than 50% internal carotid stenoses, but when this is combined with pulsed Doppler in the technique of duplex scanning, accurate results may be obtained.

Arterial Occlusive Diseases↗