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Biomedical subjects

I Isherwood

Publications and source records attributed to I Isherwood.

At least 37 records · Page 2Linked to original sources
PubMed1989

Diagnosis and assessment of mitral and aortic valve disease by cine-flow magnetic resonance imaging.

Seventy-six aortic and mitral valves, in 44 patients and 5 normal volunteers, were studied by Cine-Flow MRI (on a 0.26-T superconducting magnet system), utilizing compound oblique imaging planes and a Field Echo Even Rephasing sequence. All patients had had cardiac catheterization and echocardiography. All patients with valvular stenosis and aortic sclerosis (n = 45) showed complete signal loss distal to the respective valve. Length of signal loss distal to the aortic valve in those in whom it was measured (n = 15) allowed differentiation of aortic stenosis (n = 9) from sclerosis (n = 6). This also permitted grading of stenosis with highly significant correlation (T = 0.86; P less than 0.002) with pressure gradient measurement. In mitral stenosis (n = 12) calculation of the area of signal loss distal to the mitral valve as a percentage of left ventricular cross-sectional area showed a highly significant correlation (T = 0.77; P = 0.001) with pressure gradient measurement. Clinically significant valvular regurgitation was graded by size and duration of signal loss proximal to the value with concordance with angiocardiography. It is concluded that Cine-Flow MRI has a clinical role in the diagnosis and assessment of valvular heart disease.

Adult↗
PubMed1989

The effects of angiotensin II on Doppler signals from a soft-tissue tumour.

A 10 mHz continuous-wave Doppler system has been used to detect blood flow within a sarcoma implanted in a rabbit's ear. The effects of vasoconstriction produced by intravenous angiotensin II were studied. Criteria are described that enabled differentiation of the Doppler signals from the tumour from those of the adjacent central artery. The effect of vasoconstriction upon these criteria is also described.

Angiotensin II↗
PubMed1988

Evaluation of computer advisor in the interpretation of CT images of the head.

This paper describes the evaluation of a computer advisor system (BRAINS), which was constructed to aid in the interpretation of CT images of the head. It was developed at the National Hospital for Nervous Diseases, Queen Square, London. The system was transferred, without difficulty, to an 'external', that is previously unassociated, site (the Department of Diagnostic Radiology, University of Manchester) for an external evaluation. Response of external users to the system was mixed. Many were unfamiliar with the concept of formal description of images and the evaluation demonstrated the need for a person to person training programme. Users who accessed the HELP facilities most frequently were the most successful in obtaining accurate descriptions and hence satisfactory diagnostic advice. An objective appraisal of user's success in describing images to obtain the correct diagnosis as first choice indicated that, in general, the system performed well.

Brain Diseases↗
PubMed1988

Gadolinium-DTPA as a contrast agent in magnetic resonance imaging of the brain.

One hundred patients with CT-proven intracranial disease have been studied by magnetic resonance imaging (MRI) before and after intravenous injection with Gadolinium-DTPA (Gd-DTPA), in order to assess the role and clinical efficacy of Gd-DTPA. T2-weighted spin echo sequences, although sensitive to the detection of intracranial disease, in general fail to differentiate macroscopic tumor from oedema. Following Gd-DTPA, T1-weighted spin echo sequences in primary tumours demonstrated a variable degree of contrast enhancement unrelated to histological type. Small tumours, especially acoustic neuromas and meningiomas in the posterior fossa, were rendered more conspicuous. Optimum time for scanning was between five and 25 min following injection for all lesions except those adjacent to normal enhancing structures such as nasal/sinus mucosa and pituitary gland when delayed scans up to 45 min were necessary. No differences were observed between the 0.1 and 0.2 mmol/kg Gd-DTPA concentrations used and no complications attributable to Gd-DTPA were detected. Clinical advantages of Gd-DTPA include shorter scan times, macroscopic tumour/oedema separation and improved detection of certain tumours, particularly acoustic neuromas.

Adolescent↗
PubMed1988

Plexiform trigeminal neurofibroma.

Neurofibromas of the trigeminal nerve are uncommon tumours which usually present in patients in the third or fourth decade of life as a localised mass in the posterior or middle cranial fossa. A case is described of a plexiform neurofibroma of this nerve with unusual clinical and radiological features.

Adult↗
PubMed1988

Detection of coronary artery bypass graft patency as assessed by magnetic resonance imaging.

In a study of 22 patients with 60 coronary artery bypass grafts, magnetic resonance imaging (MRI) correctly assessed graft patency or occlusion in 90% of cases when compared with selective coronary graft angiography and computed tomography. It is concluded that MRI can detect a normally functioning coronary artery bypass graft and could be used as a non-invasive technique to assess graft patency in patients presenting with post-operative angina.

Adult↗
PubMed1988

Magnetic resonance imaging of the mini-pig heart: the effect of gadolinium-DTPA on normal myocardium.

The effect of gadolinium-diethylene-triamine-penta-acetic acid (Gd-DTPA) on normal, mini-pig myocardium was investigated with magnetic resonance imaging. Results indicate that intravenous administration of Gd-DTPA produces a significant enhancement of mini-pig myocardial signal intensity, which in all cases was maintained in excess of 50 min. No significant enhancement was demonstrated in skeletal muscle.

Animals↗
PubMed1988

Magnetic resonance imaging of acoustic neuromas: the role of gadolinium-DTPA.

Magnetic resonance imaging (MRI) was performed in 20 patients with evidence on computed tomography (CT) of 21 acoustic neuromas before and after intravenous administration (0.1-0.2 mmol/kg body weight) of gadolinium-diethylene-triamine-pentaacetic acid (Gd-DTPA). Multi-section spin-echo (SE) sequences of varying repetition (TR) and echo (TE) times were performed in the transverse and coronal planes with a section thickness of 10 mm. All acoustic neuromas displayed marked enhancement on the T1-weighted (short TR/TE) SE sequence post-Gd-DTPA. The intrameatal component was particularly well demonstrated compared with non-enhanced magnetic resonance (MR) images and contrast-enhanced CT. Identification of intrameatal tumour was difficult on T2-weighted SE images and one tumour was not identified on the T1-weighted SE sequence prior to Gd-DTPA. Four of five intrameatal tumours measuring less than 8 mm could only be demonstrated on CT by using CT air meatography. Extrameatal tumour extension was demonstrated on contrast-enhanced CT, although the assessment of brain-stem involvement and displacement was not as clearly seen as on coronal MR images. In two patients with large acoustic neuromas and a cyst, the true relationship of the cyst to the tumour could only be identified on the post-Gd-DTPA scan. Magnetic resonance imaging with gadolinium-DTPA is a relatively quick, safe, well tolerated and effective method for the diagnosis of acoustic neuroma.

Adolescent↗
PubMed1988

Dynamic low-dose three-dimensional computed tomography: a preliminary study.

Three-dimensional (3D) computed tomographic reformations have been used successfully as an adjunct to standard axial computed tomography (CT) in the evaluation of disorders affecting areas of complex anatomy. The basic requirements for high-quality 3D reformations are an absence of patient movement and narrow-width transaxial sections. Speed of examination is an important factor in optimizing image quality. One hundred examinations were performed on an IGE CT 9800 scanner. For bone studies, 80 mAs and, for certain soft tissues, 140 or 200 mAs were employed with 120 kVp. The advantages of such a "low-dose" technique are significant reduction in patient skin dose and a faster examination. The main disadvantage is a reduction in signal-to-noise ratio. The image quality obtained in 3D presentations has nevertheless been sufficient to enable all bony abnormalities to be identified. Three-dimensional examinations are now being performed routinely using a dynamic mode and this "low-dose" technique.

Female↗
PubMed1987

Detection of myocardial infarction in the mini-pig using NMR imaging.

Spin-echo images of 10 myocardial infarcts in nine mini-pigs were obtained at 30 h, 3 days, and approximately 10 days postinfarction. Infarcts were not detected at all at 30 h in five out of five cases examined. At 3 days postembolization (six cases) one infarct was certainly detected, whilst at 10 days (nine cases) all infarcts were seen as high-signal areas in long TE spin-echo sequences. After 2 weeks no further infarct signal change was detected (three cases), but myocardial thinning became more evident. Using techniques similar to those reported here, early postinfarct changes in the dog have been detected by other authors. Possible reasons for this difference between pig and dog are discussed.

Animals↗
PubMed1987

Three-dimensional computed tomographic reformations of sellar and para-sellar lesions.

The purpose of this study was to determine whether diagnostically useful three-dimensional (3D) reformations could be obtained from unmodified high resolution pituitary CT scans. Twelve CT examinations in 9 patients in whom an enhancing tumour or extensive bone destruction was identified around the sella, were studied using 3D images obtained on soft tissue and bone thresholds. 3D images were considered superior to conventional CT sections and reformations for the assessment of the vascular relations of tumours with large supra-sellar components, and in cases of extensive bone erosion. In selected cases, 3D CT imaging may facilitate a faster and more comprehensive appraisal of high resolution CT studies by clarifying otherwise complex spatial relationships.

Adult↗
PubMed1987

Three-dimensional CT reformations in the assessment of congenital and traumatic cranio-facial deformities.

Standard radiography and computed tomography (CT) produce two-dimensional representations of anatomical structures under investigation. Recent developments in computer software now enable the production, from a series of conventional CT sections, of three-dimensional images of complex anatomical structures thus providing an opportunity for improved diagnosis and treatment planning.

Facial Bones↗
PubMed1987

Three-dimensional reformations of computed tomography in the assessment of facial trauma.

Three-dimensional (3D) computed tomography (CT) reformations were obtained in 15 patients presenting with facial injuries of differing severity. The 3D images were compared with standard radiographs and high resolution CT, including multiplanar reformations, and assessed under the headings of fracture detection, extent and displacement using a simple scoring system. 3D was valuable in severe trauma with multiple fractures, providing a clear demonstration of fraction extent and fragment displacement. 3D was much less useful in minor trauma in which little or no fragment displacement had occurred, and demonstrated fewer fractures overall than either radiography or CT in all categories of facial injury. When used as part of a high resolution CT examination 3D imaging can provide useful information to both radiologist and surgeon in cases of severe facial trauma.

Facial Injuries↗
PubMed1987

Three-dimensional computed tomographic scans in the planning of procedures for reconstructive craniofacial surgery.

Three-dimensional computed tomographic (3D CT) scans were used in the assessment of three cases being considered for craniofacial reconstructive surgery; the first patient had a frontal encephalocele, the second an orbital encephalocele and the third an apparent asymmetry of the face due to cervical scoliosis caused by developmental defects of the upper two cervical vertebrae. The 3D CT scans provided information which was of great help in deciding how best to manage each case.

Adolescent↗
PubMed1987

Identification of intracardiac thrombus: comparison of computed tomography and cross-sectional echocardiography.

Thirty-eight patients with conditions predisposing to intracardiac thrombus have been studied by computed tomography and cross-sectional echocardiography. Computed tomography identified 22 cases of intracardiac thrombus (13 left ventricular, eight left atrial and one right atrial). Cross-sectional echocardiography identified five of these left ventricular thrombi and the right atrial thrombus, but none of the left atrial thrombi. In addition, measurements of thrombus density on computed tomography identified a significant difference (p less than 0.02) between the density of a new compared with an organized thrombus.

Echocardiography↗