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Biomedical subjects

T Hindmarsh

Publications and source records attributed to T Hindmarsh.

At least 91 records · Page 5Linked to original sources
PubMed1977

Radiopaque marker in the tilting disc of the Björk-Shiley heart valve. Evaluation of in vivo prosthetic valve function by cineradiography.

This paper describes a new, noninvasive method for evaluating the in vivo function of the Björk-Shiley tilting disc valve in the aortic, mitral, and tricuspid positions. The tilting disc was equipped with a ring-shaped radiopaque marker, which permits visualization of the motion of the disc by both cineradiographic and fluoroscopic studies. A beam direction corresponding to the axis of motion of the disc should be sought for calculation of the prosthetic opening angle, whereas prostehtic valve closure is demonstrated by a beam direction deviating 20 to 30 degrees from the valve ring plane. Complete opening to 60 degrees and closure of the prosthetic valve, indicating free motility of the tilting disc, were confirmed by cineradiograms. The error of estimation of the in vivo opening angle is small with deviations of less than 15 degrees from the ideal beam direction and negligible for opening angles approaching 60 degrees. Deviations in two planes simultaneously cause less error than deviation in one plane. The radiopaque marker was designed to detect mechanical valve failure owing to thrombotic obstruction. The incidence of this particular complication was 8.1 per 100 patient-years after aortic valve replacement without anticoagulation treatment. With anticoagulation, this incidence was zero after aortic and 2.5 after mitral valve replacement. In our clinical experience to date, which comprises over 1,250 implants, we have not encountered a single case of primary mechanical valve dysfunction. Our current program includes a change-over to the radiopaque tilting-disc model of the Björk-Shiley prosthesis, which was introduced at this clinic in March, 1975.

Aortic Valve↗
PubMed1975

Lumbar myelography with meglumine iocarmate and metrizamide.

Metrizamide and meglumine iocarmate (Dimer-X), which at present are the contrast media for myelography best tolerated by central nervous system, were compared in a double-blind test comprising a total of 86 patients, all with symptoms of lumbar or sacral root involvement. Symptoms appearing were recorded using a standard interview formula 24 hoaurs after myelography. EEG, routine laboratory analyses of CSF and neurologic examinations were also made. In some cases CSF paper electrophoresis, CSF pressure recordings and determination of CSF iodine content were obtained.

Adult↗
PubMed1975

Myelography in metastatic lesions.

The radiologic appearances at gas myelography were analysed in 57 metastatic lesions, all histologically verified, or having known primary tumours. Five of these cases were also examined with a water-soluble contrast medium, metrizamide. The results were correlated to the findings at surgery and to tumour pathology. It is concluded that myelographic findings simulating juxtamedullary growth are usually due to local indentation of the dura by the extradural tumour, and not to intradural extension.

Adolescent↗
PubMed1975

Elimination of water-soluble contrast media from the subarachnoid space. Investigation with computer tomography.

Contrast media injected into the subarachnoid space may be eliminated in two different ways, by diffusion through the meningeal membranes or by transport through these CSF pathways. The latter mode of transport may be examined using computer assisted tomography of the head. Diffusion predominants with contrast media of low molecular weight, such as methiodal sodium. The transport through the CSF cihculation increases when contrast media of high molecular weight such as meglumine iocarmate and metrizamide are used.

Diagnosis, Computer-Assisted↗
PubMedDate not supplied

Positron emission tomography compared with magnetic resonance imaging and computed tomography in supratentorial gliomas using multiple stereotactic biopsies as reference.

Ten patients with findings at computed tomography (CT) suggesting intracranial supratentorial glioma were investigated to compare the diagnostic efficacy of this technique with that of positron emission tomography (PET) using 11C-methionine and examinations with magnetic resonance (MR). The findings were related to histopathologic examination of serial stereotactic biopsies, which were guided by the appearance of the lesions on PET examination. To obtain corresponding slice orientation with the different examination techniques, an individually shaped helmet fixation was used. However, in 3 cases this fixation device could not be used for MR. Histopathologic diagnosis, obtained in all cases from multiple target stereotactic biopsies, included glioma in 9 patients and reactive gliosis in one case. A detailed comparison of the three imaging techniques and the findings at stereotactic biopsies was possible in 7 patients, while in 3 patients comparison with MR was less exact due to the patient's refusal to wear the helmet during this examination. MR was the most accurate method for outlining the total extent of a lesion, i.e. the tumor and the edema surrounding it. Four lesions had homogeneous signal characteristics and in 6 lesions two (or more) compartments could be distinguished with MR. In 5 cases the MR findings were in complete agreement with the histopathologic findings. However, a thorough correlation between signal characteristics and histology was not possible. Using PET the occurrence and the extent of tumor tissue was correctly predicted in 7 patients. The PET was normal in one case. Findings at CT were in agreement with the histopathologic diagnosis in 5 patients. MR was the most sensitive method for the detection of lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Iohexol in lumbar myelography: preliminary results from an open, noncomparative multicenter clinical study.

This is a preliminary report of the first clinical trials using iohexol as a contrast agent in lumbar myelography. The study was noncomparative and involved 82 adult patients in four centers. Iohexol doses of 10-15 ml (180 mg I/ml) were administered and clinical and laboratory tests were performed before and at intervals during 48 hr after myelography. Side effects were noted in 29 (35%) of 82 patients. Spinal repuncture 6 or 24 hr after myelography was performed in 51 patients. No significant increases in cerebrospinal fluid parameters were seen. No seizures or spikes on electroencephalography were seen.

Adult↗
PubMedDate not supplied

Comparative double-blind investigation of meglumine metrizoate, metrizamide, and iohexol in carotid angiography.

The new nonionic contrast medium iohexol (Omnipaque) was compared with its predecessor metrizamide (Amipaque) and with the conventional ionic medium meglumine metrizoate (Isopaque Cerebral) in carotid angiography using a double-blind crossover technique. The results indicated that iohexol and metrizamide caused less discomfort than the ionic medium. The circulatory effects of the three media were generally mild, and the diagnostic effectiveness was comparable when the iodine concentration was kept in the range of 280-300 mg I/ml.

Adolescent↗