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Biomedical subjects

A T Irvine

Publications and source records attributed to A T Irvine.

15 recordsLinked to original sources
PubMed1997

The role of CT and MR in imaging the complications of sickle cell disease.

Sickle cell disease is the most common inherited haemoglobinopathy described. Complications of sickle cell disease (SCD) are due to chronic haemolysis of fragile red cells or secondary to vascular occlusion by sickled red cells with subsequent tissue infarction. Traditionally plain film radiography has been the mainstay in the assessment of patients with SCD, but increasingly magnetic resonance (MR) imaging and computed tomography (CT) are being used. In this review the imaging features of a range of complications of SCD are demonstrated with particular emphasis on CT and MR.

Anemia, Sickle Cell↗
PubMed1997

Gadopentate dimeglumine as an alternative contrast agent for use in interventional procedures.

Renal failure due to iodinated contrast media is a serious complication of peripheral angiography in patients with impaired renal function. Gadolinium based agents which are widely used in magnetic resonance imaging have no adverse renal toxicity at recommended doses. These agents have sufficient radiographic density to be seen using digital subtraction equipment. We describe the use of undiluted gadopentate dimeglumine as the radiographic contrast agent in two patients who underwent complex interventional procedures.

Acute Kidney Injury↗
PubMed1996

Coronary subclavian steal syndrome following coronary by-pass surgery.

The coronary steal syndrome is an uncommon but well recognised occurrence following coronary artery by-pass surgery using the internal mammary artery. We report a case of coronary steal successfully treated with percutaneous transluminal angioplasty of a subclavian stenosis.

Angioplasty, Balloon↗
PubMed1995

Improved MR venography: use of fast short inversion time inversion-recovery technique in evaluation of venous angiomas.

Eleven patients (five female and six male, aged 6-67 years) with venous angiomas underwent axial and coronal T1-weighted and fast short inversion time inversion-recovery (STIR) magnetic resonance (MR) imaging to assess the full extent of the malformations. Images were assessed subjectively by the authors in a nonblinded study. In all patients, fast STIR images depicted more anatomic detail than did T1-weighted images and depicted venous angiomas more clearly than did contrast material-enhanced CT scans but did not help discrimination of arteries and veins.

Adolescent↗
PubMed1995

Case report: therapeutic transcatheter embolotherapy in the control of recurrent haemorrhage from lymphoma of the small bowel.

Lymphoma is one of the commonest primary malignancies of the small bowel. Gastrointestinal tract haemorrhage is a relatively infrequent presenting feature or complication. We describe the use of repeated transcatheter embolization as the primary treatment in the control of recurrent haemorrhage from the small bowel in a patient with B-cell lymphoma. Few cases of transcatheter embolotherapy have been described in such situations. This form of treatment is a therapeutic option in those unfit for transcatheter vasoconstrictor infusion or surgery.

Aged↗
PubMed1990

An evaluation of 99mTc-HMPAO uptake in cerebral gliomas--a comparison with X-ray CT.

Nineteen patients with biopsy-proven cerebral gliomas were studied with 99mTc-HMPAO single photon emission tomography (SPECT) imaging and X-ray computed tomography (CT). The uptake of 99mTc-HMPAO was correlated with tumour size and morphology as shown by X-ray CT, and overall patient survival. It appears that uptake of 99mTc-HMPAO is associated with larger, ill-defined tumours and was an adverse factor in patient survival. In those tumours with normal or increased uptake, 99mTc-HMPAO imaging is useful in distinguishing the tumour margin from surrounding oedema.

Brain Neoplasms↗
PubMed1990

Thyroid imaging using positron emission tomography--a comparison with ultrasound imaging and conventional scintigraphy in thyrotoxicosis.

Forty-six comparative studies were performed on 41 patients with hyperthyroidism. Clinically these comprised two groups: those with Graves' disease, and those with multinodular goitre. All patients underwent an ultrasound examination and positron emission tomography (PET) using 124I, then gamma camera pinhole imaging following their 131I therapy administration. Although the 131I pinhole imaging was not performed for diagnostic purposes, there was good correlation (78% agreement) between it and 124I PET in determining relative lobe size. Hence either imaging modality could be used as an indicator of the relative radiation dose delivered to each thyroid lobe at a macroscopic level. In terms of gland morphology the PET images corresponded well to the high resolution ultrasound images (78% agreement), unlike the pinhole images which correlated poorly (only 28% agreement). The results showed that PET imaging gives better anatomical and physiological detail than 131I pinhole imaging. In 77% of cases where the pinhole image showed a uniform distribution of radioisotope, the improved spatial resolution of the PET images revealed non-homogeneous distribution indicating a non-uniform distribution of radiation dose. Since all dosimetry calculations are based on the assumption of uniform distribution of radioiodine, this non-uniformity could possibly have important consequences in the outcome of radioiodine therapy in thyrotoxicosis.

Adult↗
PubMed1988

Deconvolution of emission tomographic data: a clinical evaluation.

A method of improving the quality of images in single photon emission computed tomography (SPECT) is demonstrated using transaxial images of the liver and brain. Deconvolution of the nuclear medicine data by a point source response function (PSRF) acquired previously in a scattering medium attempts to compensate for scattered radiation within the patient. The average geometric response of the collimator of the gamma camera is also compensated for with this technique. Three patients with known metastatic lesions in the liver and three with primary lesions in the brain were imaged. Clinical assessment of reconstructed slices both before and after deconvolution demonstrates that compensating for the effects of scatter and of collimator blurring leads to enhanced detail of pathological lesions. In all cases, cold lesions seen prior to deconvolution were enhanced in detail and, in addition, new lesions were seen with this technique.

Adult↗
PubMed1987

Air-plethysmography and the effect of elastic compression on venous hemodynamics of the leg.

Leg volume changes during exercise have been measured in absolute units (milliliters) by means of a new method of air-plethysmography. Venous volume (VV), venous filling time, and venous filling index on standing from the recumbent position, ejected volume (EV) and ejection fraction (EF = EV x 100/VV) with one tiptoe movement, and residual volume (RV) and residual volume fraction (RVF = RV x 100/VV) after 10 tiptoe movements were measured in normal limbs, limbs with superficial venous incompetence, and limbs with deep venous disease. The same measurements were repeated with a graduated medium compression stocking in limbs with SVI and graduated high compression stockings in limbs with DVD. Ambulatory venous pressure was measured at the same time, with a needle in a vein in the foot. The results indicate that this method of air-plethysmography is not only of diagnostic value but offers a new and unique technique to assess and study the hemodynamic effects of different forms of elastic compression. The lower ambulatory venous pressure, produced by the elastic compression, was the result of a reduction in reflux and an improvement in the calf muscle ejecting ability during rhythmic exercise.

Adult↗