Biomedical subjects
Publications and source records attributed to B M Tress.
Recent successes in the management of acute ischaemic stroke have emphasized the importance of early diagnosis and treatment. Patients with a 'brain attack' are best managed as a medical emergency. Imaging is vital in identifying infarct as well as tissue at risk and is best done with ultrafast magnetic resonance imaging.
RATIONALE AND OBJECTIVES: Magnetic resonance contrast enhancement depends on the timing of image acquisition. Human trials have demonstrated efficacy of renal artery stents on salvage of renal function. This study assessed the ability of dynamic gadolinium (Gd)-DTPA administration to demonstrate renal and iliac artery stent patency compared to conventional angiography as the gold standard. METHODS: Seven subjects with eight stents referred for angiography underwent dynamic magnetic resonance studies, all with renal artery stenting. All were examined with conventional angiography and after dynamic Gd-DTPA infusion. Coronal magnetic resonance images were acquired using a GE Signa 1.5 T magnet (fast spoiled gradient echo; echo time = 4.2 ms; repetition time = 68-150 ms; flip angle = 75 degrees) 0 to 600 seconds after 0.1 mmol/Kg Gd-DTPA intravenous bolus injection during sequential breath-hold acquisitions 13 to 32 seconds each. RESULTS: All eight stents were visualized with 100% accurate patency documentation. CONCLUSIONS: Fast spoiled gradient echo magnetic resonance imaging with bolus Gd-DTPA administration can provide adequate time and spatial resolution to demonstrate arterial stent patency.
OBJECTIVES: We examined the utility of echoplanar magnetic resonance perfusion imaging and diffusion-weighted imaging (DWI) in predicting stroke evolution and outcome in 18 patients with acute hemispheric infarction. METHODS: Patients were studied within 24 hours (mean, 12.2 hours), subacutely (mean, 4.7 days), and at outcome (mean, 84 days). Comparisons were made between infarction volumes as measured on perfusion imaging (PI) and isotropic DWI maps, clinical assessment scales (Canadian Neurological Scale, Barthel Index, and Rankin Scale), and final infarct volume (T2-weighted MRI). RESULTS: Acute PI lesion volumes correlated with acute neurologic state, clinical outcome, and final infarct volume. Acute DWI lesions correlated less robustly with acute neurologic state, but correlated well with clinical outcome and final infarct volume. Three of six possible patterns of abnormalities were seen: PI lesion larger than DWI lesion (65%), PI lesion smaller than DWI lesion (12%), and DWI lesion but no PI lesion (23%). A pattern of a PI lesion larger than the DWI lesion predicted DWI expansion into surrounding hypoperfused tissue (p < 0.05). In the other two patterns, DWI lesions did not enlarge, suggesting that no significant increase in ischemic lesion size occurs in the absence of a larger perfusion deficit. CONCLUSIONS: Combined early PI and DWI can define different acute infarct patterns, which may allow the selection of rational therapeutic strategies based on the presence or absence of potentially salvageable ischemic tissue.
Explore the source record for details and available documents.
PURPOSE: To determine the histopathologic findings of patellar tendinosis ("jumper's knee") demonstrated with ultrasonography (US) and magnetic resonance (MR) imaging. MATERIALS AND METHODS: Twenty-four athletes (28 knees) with jumper's knee (23 men, one women; mean age, 30.9 years) scheduled to undergo open tenotomy underwent US patellar tendon examination. Seventeen patients (19 knees) also underwent MR imaging. Tissue was obtained for histopathologic examination in all 28 cases. Eleven age-, height-, and weight-matched athletes (22 knees) without previous knee symptoms served as control subjects for the US examination. Control material for histopathologic examination was obtained in 20 cadavers (39 knees). Data were analyzed with standard statistical methods. RESULTS: MR imaging and US both revealed an abnormal zone at the proximal patellar tendon attachment. Histopathologic examination revealed mucoid degeneration in all tendons in patients and in 8% (three of 39) of tendons in cadavers (P < .01). CONCLUSION: Jumper's knee is characterized by consistent changes at MR imaging, US, and histopathologic examination and is appropriately described as patellar tendinosis.
OBJECTIVE: To compare the acute Allen's Prognostic Score, Canadian Neurological Score, and subacute Barthel Index as predictors of outcome functional status and infarct size at 3 months in patients with acute cortical infarction. DESIGN: A prospective study of acute stroke predictors and outcome measurements in a cohort of sequential hospitalized patients. PATIENTS: Fifty-one patients with acute cortical infarction and without previous disability assessed 24 hours after onset with Allen's Prognostic Score and the Canadian Neurological Score and at 7 days with the Barthel Index. MAIN OUTCOME MEASURES: Mortality, Barthel Index, and volumetric measurement of infarct size on computed tomography 3 months after stroke. RESULTS: There were seven deaths. The outcome Barthel Index was measured in all 44 survivors, of whom 29 had computed tomography at the time outcome was determined. In a multivariate analysis, functional outcome was best predicted by Allen's Prognostic Score, a score of less than -15 having a sensitivity of 82% and specificity of 97% in predicting a poor outcome (Barthel Index, < or = 12 or death). Volumetric tissue loss was predicted only by Allen's Prognostic Score (r = .62, P < .001). CONCLUSIONS: Allen's Prognostic Score is a robust predictor of both functional outcome and tissue loss in acute cortical infarction and has a potentially important role in the analysis of the results of acute stroke intervention trials.
A case of malignant granular cell tumour of the sciatic nerve is presented. Computed tomography demonstrated isodensity with muscle and minimal enhancement. Magnetic resonance demonstrated T1 isointensity with muscle with marked enhancement, and isointensity with fat on proton and T2 images. Pathological evidence is presented for its probable Schwann cell histogenesis.
Cerebral venography and manometry in nine patients with idiopathic intracranial hypertension consistently showed venous hypertension in the superior sagittal sinus and proximal transverse sinuses, with a significant drop in venous pressure at the level of the lateral third of the transverse sinus. The abnormality, clearly demonstrated by manometry, was not well shown on the venous phase of cerebral angiography. The appearance of the transverse sinus on venography varied from smooth tapered narrowing to discrete intraluminal filling defects that resembled mural thrombi. Two patients with intracranial hypertension due to minocycline did not show venous hypertension.
The aim of this study was to evaluate the safety of the 'open' method of contrast medium delivery in the angiographic theatre, in which contrast medium is decanted into open galley pots on sterile trolleys. The air bacterial load within the angiographic theatre was sampled before and during angiographic procedures. The relationship of staff and patient activity to bacterial load was assessed. Samples of Iopromide (Ultravist 370; Schering Pty Ltd, Sydney, NSW, Australia) decanted into galley pots were taken for bacterial culture at the end of seven patient procedures. Air bacterial loads were comparable with operating theatre levels and were heaviest during staff activity. Three of seven samples taken at the end of angiographic procedures from air-exposed galley pots yielded contaminants, but the number of bacteria was below that required to produce septicaemia under normal conditions. These results suggest that the open system of contrast medium delivery can be safely used, providing that bacterial checks of room contamination are performed and personnel entry into the theatre is strictly limited.
Preparations of Iopromide (Ultravist 370; Schering Pty Ltd, Sydney, NSW, Australia), brain/heart infusion broth (BHI; positive growth control) and distilled water (negative control) were inoculated with 10(3) to 10(4) Pseudomonas aeruginosa, Escherichia coli or Staphylococcus aureus cells and incubated at 37 degrees C. Slow decreases (up to one log) were observed in each organism's count in Iopromide and distilled water at room temperature and in S. aureus and E. coli in Iopromide and distilled water at 35 degrees C until 6-8 h, when counts stabilized. BHI cultures showed logarithmic increases. P. aeruginosa counts increased (half log over 8 h) in Ultravist at 37 degrees C. Radiology laboratories were shown to have similar airborne bacterial loads to operating theatres. Samples from repeatedly entered Iopromide bottles showed no contamination. Multiple intravenous doses from a single bottle of non-ionic contrast medium can safely be used as a cost-saving measure provided scrupulous attention is paid to aseptic preparation. Unused decanted contrast medium should be discarded after 4 h.
BACKGROUND: Alzheimer's disease is the commonest cause of dementia. Clinical diagnosis of Alzheimer's disease may be difficult. Magnetic resonance imaging has a role to play in diagnosis. AIM: To assess whether volumetric and/or visual assessment of the mesial temporal structures is useful in separating patients with Alzheimer's disease from age matched controls. METHODS: Twenty-four patients with Alzheimer's disease diagnosed by NINCDS/ADRDA criteria and 15 age matched controls were studied with magnetic resonance imaging (MRI) and volumetric techniques. Segmented volumes of the mesial temporal structures were assessed visually and volumetrically. RESULTS: Volumetric analysis demonstrated significant (p < .001) differences between the two groups, but showed overlap in individual cases. Discriminant function analysis predicted correct group membership (patient or control) in 85% of cases. Visual assessment alone demonstrated a sensitivity of 92% and a specificity of 93% in distinguishing the Alzheimer patients from controls. CONCLUSION: Volumetric and visual assessment of the mesial temporal structures is useful in separating Alzheimer patients from controls. Overlap is present in individual cases. Visual assessment was as useful in separating the two groups as the volumetric analysis.
Explore the source record for details and available documents.
The results of 4504 0.3 T magnetic resonance (MR) examinations, of which 3262 had clinical follow up are described. The overall true positive rate of MR imaging was 72%, with a range of 69-100%. While the best results were obtained for evaluation of spinal cord syrinx and normal cerebral examinations, 31% of patients with cerebral demyelination were incorrectly diagnosed. The false positive rate was relatively low (3-5% in most cases), but a significant 17% of patients considered to have normal cerebral examinations were later shown to have pathology. While the true positive rate of magnetic resonance imaging was greater than that of the suspected clinical diagnosis (37% correct), the results of this assessment at 0.3 T are significantly poorer than those previously published at 1.5 T.
The objective of this paper is to describe the basic physical principles important in magnetic resonance angiography (MRA). The data used were obtained from recent articles on MRA retrieved from Index Medicus 1985-92 and direct experience working with prototype MRA sequences. The information is presented in a manner suitable for those unfamiliar with the principles of MRA and magnetic resonance imaging (MRI). Magnetic resonance angiography is an important method that can be used to obtain angiograms without the injection of intravascular contrast medium. It is already proving to be of clinical use in the assessment of vascular disease.
The objective of this paper is to describe clinical applications of magnetic resonance angiography. The data used were obtained from recent articles on vascular and flow magnetic resonance imaging retrieved from Index Medicus 1988-91. Other contributions were from the 19th Annual Meeting of the American Society of Neuroradiology held in Washington DC in June 1991 and the 10th Annual Conference of the Society of Magnetic Resonance in Medicine in August 1991. The data are presented in such a way as to give the reader unfamiliar with magnetic resonance a basic insight into some of the new imaging techniques. Magnetic resonance imaging is advancing at a rapid rate. Magnetic resonance angiography is already finding many areas of clinical use with concomitant reduction in conventional angiographic and duplex Doppler ultrasound procedures.
Explore the source record for details and available documents.
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.
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.