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A Blane

Publications and source records attributed to A Blane.

5 recordsLinked to original sources
PubMed2002

Repeatability of long and short echo-time in vivo proton chemical-shift imaging.

We carried out long (145 ms) and short (25 ms) echo time spectroscopic imaging of the brain (chemical-shift imaging, CSI) on two occasions 1 week apart on 15 healthy individuals. We found coefficients of variation (CVs) generally in the range 10-25% for long and 15-30% for short echo-time measurements. The CVs of metabolite ratios were higher by about 5-10%. Limits of agreement (defined as mean+/-2 SD of the week 1-week 2 differences) were wider at the shorter echo time. The modest repeatability may be due in part to the difficulty of repositioning spectroscopic voxels at a scale of 1 mm. The generally higher CVs and wider limits of agreement at TE25 ms suggest that the increased spectral complexity more than offsets the theoretical advantage of increased signal at short echo-times. Analysis of variance general linear modelling of metabolites and metabolite ratios showed that, in general, the subject, region of the brain and hemisphere were more important than the occasion in explaining the variability of results. Unless information on short-T2 metabolites is specifically required, better results can probably be achieved with longer echo-times. The magnitude of the CVs needs to be taken into account in the calculation of sample size for cross-sectional or linear studies.

Adult↗
PubMed2000

Memory impairment in out-of-hospital cardiac arrest survivors is associated with global reduction in brain volume, not focal hippocampal injury.

BACKGROUND AND PURPOSE: More than 30% of out-of-hospital cardiac arrest (OHCA) survivors suffer significant memory impairment. The hippocampus may be vulnerable to hypoxic injury during cardiac arrest. The purpose of this study was to determine whether selective hippocampal injury is the substrate for this memory impairment. METHODS: Seventeen OHCA survivors and 12 patients with uncomplicated myocardial infarction were studied. OHCA survivors were divided into those with impaired and intact memory. Memory was assessed by use of the Rivermead Behavioural Memory Test and Doors and People Test. MRI was used to determine intracranial, whole-brain, amygdala-hippocampal complex, and temporal lobe volumes. Brain structure was also examined by statistical parametric mapping. RESULTS: Left amygdala-hippocampal volume was reduced in memory-impaired OHCA victims compared with control subjects (mean 3. 93 cm(3) and 95% CI 3.50 to 4.36 cm(3) versus mean 4.65 cm(3) and 95% CI 4.37 to 4.93 cm(3); P=0.002). Left temporal lobe and whole-brain volumes were also reduced. There were no differences in amygdala-hippocampal volume indexed against ipsilateral temporal lobe volume. Significant correlations were observed between total brain volume and Rivermead Behavioural Memory Test (r=0.56, P<0.05) and Doors and People Test (r=0.67, P<0.01) scores in OHCA survivors. Both recall and recognition were compromised in memory-impaired subjects. Statistical parametric mapping did not detect focal brain abnormalities in these subjects. Global cerebral atrophy was confirmed by qualitative assessment. CONCLUSIONS: Memory impairment in OHCA survivors is associated with global cerebral atrophy, not selective hippocampal damage. Rehabilitation protocols need to account for the global nature of the brain injury.

Aged↗
PubMed1992

Quantitative early phase scintigraphy in the prediction of healing of tibial fractures.

Imaging with technetium-99m methylene diphosphonate (99mTc-MDP) is established in the diagnosis of infection, neoplasia and ischaemic necrosis in orthopaedic practice, but its role in fracture healing is less well-defined. Previous studies have shown a relationship between fracture site activity (region A), activity in adjacent normal bone (region C) and time to union. The predictive value of the A/C ratio of the image obtained 300-800 s after injection was assessed in a prospective study of 50 patients with closed tibial fractures managed with plaster casts, external fixators and intramedullary nails. There were significant differences in absolute uptake and A/C ratio between the three groups (P less than 0.05), but this was not related to time to union. Reamed nailing alters the distribution of 99m-Tc-MDP uptake so as to reduce the A/C ratio (1.10 +/- 0.20), but there is a promising role for early phase bone scanning in non-operative (A/C = 1.40 +/- 0.21) or externally fixed (A/C = 1.26 +/- 0.22) fractures in conjunction with other non-invasive methods of monitoring the biomechanical environment.

Adolescent↗
PubMed1989

Differential regulation of right and left ventricular levels of atrial natriuretic factor mRNA and peptide.

Over a 16-day period post-hypophysectomy both atrial natriuretic factor (ANF) mRNA and peptide levels were quite differently regulated in right and left ventricles. In the right ventricle ANF mRNA levels showed a large increase 2 days post-hypophysectomy, and returned to control levels by day 8. In the left ventricle mRNA levels doubled by day 2, and continued to rise to reach plateau levels (approximately 3-fold control) 8-16 days post-hypophysectomy. Tissue levels of ANF peptide were also measured by radioimmunoassay over the same time period. Right ventricular ANF levels rose 10-fold 2 days post-hypophysectomy, and returned to 3 times control levels by 8 days, mirroring the changes in mRNA. In the left ventricle, however, ANF peptide levels did not change significantly from intact values over the entire 16-day period following hypophysectomy despite the progressive increase in ANF mRNA levels in this tissue, suggesting that the dichotomy between mRNA and peptide levels in the left ventricle reflects an increased rate of peptide secretion.

Animals↗