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Biomedical subjects

B M Tress

Publications and source records attributed to B M Tress.

At least 19 recordsLinked to original sources

Prevertebral swelling in cervical spine injury: identification of ligament injury with magnetic resonance imaging.

In a retrospective analysis of 27 consecutive patients with acute cervical spine injury who underwent Magnetic Resonance (MR) Imaging, 14 had prevertebral soft tissue swelling on initial lateral radiographs, of whom 13 had anterior longitudinal ligament disruption on MR. Of the eight patients who had isolated prevertebral swelling in the absence of vertebral body fracture or significant subluxation, seven had anterior longitudinal ligament disruption shown on MR imaging. Of the patients with MR documented ligament injury, three had dynamic flexion-extension radiographs within 2 weeks of injury and all demonstrated cervical instability. As cervical prevertebral swelling following trauma was indicative of ligament injury in nearly half the patients, this finding should prompt clinical and radiographic follow-up to exclude spinal instability.

Adolescent

Suggested MRI criteria for surgical decompression in acute spinal cord injury. Preliminary observations.

The effect of spinal cord compression identified with magnetic resonance imaging (MRI), on neurological prognosis, was retrospectively evaluated in 36 patients with acute spinal cord injury. Of the 21 patients without cord compression, 16 had potentially reversible injury (normal spinal cord or cord oedema), all having functional recovery. Of the 15 patients with cord compression, 3 had operative decompression. In the 12 patients who did not undergo surgery, the degree of recovery was directly related to the magnitude of spinal cord compression, only one of the patients with moderate or marked cord compression having useful motor function at follow up. In contrast, the 3 patients with surgical decompression had at least 2 grades of improvement, all having functional recovery. These findings raise the possibility that MRI may be used to identify a patient group who will benefit from surgical decompression. A numerical index is proposed to prospectively identify patients for surgical decompression, and further studies are underway to evaluate this.

Adolescent

A comparison between M.R.I. and C.T. in acute spinal trauma.

Magnetic Resonance Imaging (MRI) at 0.3T and Computed Tomography (CT) were compared in the retrospective evaluation of 34 patients with acute spinal cord injury. MRI was highly accurate in the imaging of vertebral body fracture, and spondylitic changes, and is the method of choice for imaging ligament injury, traumatic disc protrusion and spinal cord compression. It was also useful for the identification of subtle subluxations in the sagittal plane. CT remains the method of choice for imaging neural arch fractures. MRI at 0.3T is a valid technique for assessing patients with acute spinal trauma.

Acute Disease

Acute stroke outcome: effects of stroke type and risk factors.

We studied 925 consecutive patients hospitalised with acute stroke to determine how stroke type, age, gender and risk factors influence acute, in-hospital outcome. Stroke types included carotid territory cortical or large subcortical infarction (52%), vertebrobasilar infarction (12%), lacunar infarction (11%), intracerebral haemorrhage (16%), and subarachnoid haemorrhage (9%). Mean age (mean +/- 1 SD) was 66 +/- 15 years, but patients with cerebral infarction were older than those with cerebral haemorrhage. The prevalence of hypertension, diabetes mellitus and cardiac disease increased with age across all stroke types, while the prevalence of smoking decreased with age. Mortality was 19% overall, but varied significantly between stroke types, highest in intracerebral haemorrhage (34%), and lowest in lacunar infarction (1%). Age had a marked adverse effect on mortality, independent of stroke type, the probability of death increasing by 3 +/- 0.5% per year from 20-92 years, whereas gender had no effect. Cardiac disease and diabetes were independent adverse prognostic factors (Odds Ratios 1.6 and 1.5 respectively). Cerebral haemorrhage, age, cardiac disease and diabetes all independently worsen acute stroke outcome.

Acute Disease

Epileptic seizures in acute stroke.

We evaluated prospectively the incidence of early seizures in 1000 consecutive patients with stroke and transient ischemic attacks to determine whether seizure occurrence correlates with stroke type, pathogenesis, or outcome. Seizures occurred in 44 patients (4.4%; SE, 0.7%), including 10 (15.4%) of 65 (SE, 4.5%) with lobar or extensive hemorrhage, 6 (8.5%) of 71 (SE, 3.3%) with subarachnoid hemorrhage, 24 (6.5%) of 370 (SE, 1.3%) with cortical infarction, and 4 (3.7%) of 109 (SE, 1.8%) with hemispheric transient ischemic attacks. Lacunar infarcts and deep hemorrhages were not associated with seizures. Arteriovenous malformation was a common cause of lobar hemorrhage with early seizures, but in cortical infarcts there was no association between seizure occurrence and pathogenesis. Seizures generally occurred within 48 hours of stroke onset, were usually single, partial, and readily controlled. Seizures were not associated with a higher mortality or worse functional outcome.

Acute Disease

CT of the spine: are plain spine radiographs necessary?

This study was designed to determine whether plain radiographs added any information of clinical significance to the information provided by CT (computed tomography) and its standard digital radiographs in 100 patients presenting for CT of the lumbar spine and 46 patients presenting for cervical spine CT. In only three (3%) of the lumbar studies and two (4.3%) of the cervical studies did the plain radiographs add diagnostic information. The added diagnostic information did not affect patient management in all cases with indications other than trauma. Good quality oblique cervical spine digital radiographs were obtained in 10 cases simply by moving the tube and detectors to the 45 degrees and 135 degrees azimuths. The evidence from this study suggests that when a CT examination of lumbar or cervical spines is planned on a high resolution CT scanner for indications other than trauma, a conventional plain radiographic examination can be omitted in the first instance.

Cervical Vertebrae

Costs of magnetic resonance imaging services in public hospitals.

Audited cost data from two public hospital installations participating in a trial of the utilisation and efficacy of magnetic resonance imaging are presented. The data cover the period July 1987 to June 1988 when both installations had attained stable patterns of operation. One hospital operated a superconductive system and the other a resistive magnetic resonance imaging unit. Depreciation and salaries represented the major components of cost.

Australia

Hippocampal sclerosis can be reliably detected by magnetic resonance imaging.

Two independent blinded observers reported the preoperative MRIs in a series of 81 consecutive patients with intractable temporal lobe epilepsy who were undergoing temporal lobectomy. We then compared the nature and lateralization of the MRI abnormalities with the pathologic diagnosis and the side of lobectomy. The MRI criteria of hippocampal sclerosis were an increased T2-weighted signal and the signal's confinement to a unilaterally small hippocampus. Imaging was performed in coronal and axial planes, specially orientated along and perpendicular to the long axis of the hippocampal body. We found diagnostic MRI abnormalities in 25 of the 27 cases with pathologically proven hippocampal sclerosis (sensitivity 93%, specificity 86%). In addition, we detected all 13 foreign tissue lesions on MRI. Overall, we detected lateralized lesions on MRI that correctly predicted the side of the epileptogenic temporal lobe in 72 cases (89%), with 2 possible errors. A learning effect in appreciating the relatively subtle MRI changes of hippocampal sclerosis was apparent in our later cases, as shown by an improved correlation between the 2 observers. This study demonstrates that hippocampal sclerosis can be identified on MRI with a high degree of sensitivity and specificity.

Brain Neoplasms

MRI--the investigation of choice in syringomyelia?

During a 12 month period of operation of a 0.3 Tesla MRI iron cored resistive scanner 74 cases of syringomyelia were diagnosed on clinical, radiological and/or surgical grounds. Without knowledge of any clinical or radiological data the syrinxes were classified into five groups--idiopathic, idiopathic associated with Chiari malformation, tumour associated, post-traumatic and arachnoiditis associated--and the lesion characteristics within each group were compared. Although MRI was extremely sensitive in picking up even small syrinxes, there was considerable overlap of MRI characteristics across the sub-groups, so that two post-traumatic syrinxes had lesion characteristics identifiable with those of tumour syrinx and one intramedullary tumour syrinx had the MRI characteristics of a benign, idiopathic syrinx. It is concluded that meticulous attention to technique, including axial as well as sagittal T1 weighted sequences, and the administration of intravenous paramagnetic contrast media are necessary for detection and accurate classification of syrinxes.

Adult

Magnetic resonance imaging in posterior circulation infarction: impact on diagnosis and management.

To compare the diagnostic yield of magnetic resonance imaging (MRI) with computed tomography (CT) in posterior circulation infarction, we used proton MRI with a 0.3 Tesla magnet and a 3rd generation CT scanner in 25 patients. Age-matched controls were compared in a blinded fashion. Seventeen patients (68%) showed relevant pathology on MRI not seen on CT, 11 with normal CT and six with more extensive lesions, chiefly in the brain stem. Evidence of abnormal vertebrobasilar blood flow was seen in 8/25 (32%) of patients, suggested by vascular high intensity signals on MRI. Two tissue and one flow abnormality were seen in the control group. MRI provides additional information concerning infarct site, extent and pathogenesis in posterior circulation infarction.

Adult

Spontaneous internal carotid artery dissection presenting as hypoglossal nerve palsy.

A 42-year-old man presented with right temporal headache, dysarthria, and dysphagia. On examination, he had a right hypoglossal nerve palsy. The diagnosis of right internal carotid artery dissection was suggested by magnetic resonance imaging and confirmed by carotid angiography. A dynamic computed tomogram demonstrated enlargement of the carotid artery. In carotid dissection, the hypoglossal nerve may be compromised by local factors as it passes close to the carotid artery in the neck.

Adult

Dynamic CT brain scanning in the haemodynamic evaluation of cerebral arterial occlusive disease.

Dynamic cerebral CT scanning (DCT) was used to quantitatively analyse the haemodynamic effects of extracranial and intracranial arterial occlusive lesions in 17 patients with TIA's or minor cerebral infarcts. Using DCT and gamma variate curve fitting, mean transit times were determined for the terminal internal carotid arteries, middle cerebral arteries and middle cerebral-supplied Sylvian cortex at the level of the Circle of Willis. Six patients were studied sequentially, four before and after transcranial bypass surgery. No arterial or tissue delays were found in patients without haemodynamic arterial lesions or cortical infarcts. Seven of nine patients with haemodynamic, extracranial carotid lesions showed ipsilateral delays in arterial or tissue transit times. Tissue delays usually correlated with CT or clinical evidence of infarction. Improved haemodynamics in patients re-studied correlated with the effects of surgery or clinical recovery. DCT has several important limitations but has the potential to provide additional haemodynamic information about the cerebral circulation in selected patients with cerebral arterial occlusive disease.

Adult

Analysis of dynamic computed tomography scan brain images.

Dynamic computed tomography (DCT) of the brain can be used to study the transit time of first passage of a bolus injection of intravenous contrast medium. Comparison of cerebral perfusion with corresponding sites in the left and right cerebral hemispheres is of diagnostic interest because a real difference may be indicative of differential damage. A method for estimating the mean transit time and approximating its standard error, by assuming a gamma function for the response curve and an appropriate error structure, is presented. Expressed as log-linear regression, estimation is achieved by maximum likelihood using a statistical package such as GLIM or SPSSX. Statistical comparison of the mean transit time to or between corresponding sites can be made; issues of model fit and biologic interpretation need to be considered as an integral part of statistical inference. These methods enable users of CT equipment (without specific software for estimation of mean transit time) to use any log-linear routine for diagnostic purposes. An example of the fit procedure and interpretation in the light of clinical evidence is given.

Brain

Incremental dynamic computed tomography: practical method of imaging the carotid bifurcation.

A simple, practical method of applying incremental dynamic computed tomography (CT) to the imaging of 20 carotid bifurcations is described. The results are compared with those obtained by conventional carotid angiography and intravenous digital subtraction angiography (DSA). Conventional angiography provided additional information about the carotid bifurcation in only one of 14 cases, while incremental dynamic CT provided information not available from intravenous DSA in two of eight cases. Conventional brain CT is being used increasingly in the workup of patients with transient ischemic symptoms, and dynamic CT scanning at 3-mm increments requires only an extra 5 min of scanner time. The addition of incremental dynamic CT through the carotid bifurcation to the conventional brain CT scan procedure may obviate other screening tests before more definitive angiographic procedures.

Carotid Artery Diseases

Nuclear magnetic resonance imaging. Basic principles.

The physical principles underlying nuclear magnetic resonance (NMR) imaging (also known as MRI) are described. NMR is an important new non-invasive imaging modality, which does not use ionizing radiation. Its ability to map hydrogen ion distribution, and to detect two intrinsic parameters ("relaxation times") which are indicative of the immediate chemical environment of the hydrogen nuclei, results in images of superior spatial detail in the brain and spinal cord. The potential of this technique for quantitating blood flow and for the exact identification of tissues is discussed.

Blood Flow Velocity

Nuclear magnetic resonance imaging. Applications in the diagnosis of cerebrospinal diseases.

The applications of the important new diagnostic modality, nuclear magnetic resonance (NMR) imaging (or MRI), to the diagnosis of diseases of the central nervous system (CNS) are discussed. Specific examples of NMR imaging of cerebral and spinal tumours, infarction, demyelination and subdural haematomas are illustrated and compared with corresponding CT scans. The greater sensitivity of NMR, together with its ability to image in axial, coronal and sagittal planes, suggests that NMR will replace CT for many diagnostic investigations of the CNS.

Adult