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Biomedical subjects

N Tubridy

Publications and source records attributed to N Tubridy.

28 records · Page 2Linked to original sources
PubMed1999

Long term use of desmopressin for urinary symptoms in multiple sclerosis.

The benefit of desmopressin (DDAVP) in the treatment of the urinary symptoms of multiple sclerosis has until now only been shown in short crossover studies of up to 6 weeks. We report 19 patients who have used the drug for an average of 2 years and 4 months, 18 of whom confirmed continued dramatic benefit without any obvious change in dosage used or efficacy and with few side effects. Ten of the 19 patients had also used DDAVP during daytime for special occasions with notable success. This is the first study to suggest that DDAVP is safe and effective in long term use in MS.

Adult↗
PubMed1998

Optimisation of unenhanced MRI for detection of lesions in multiple sclerosis: a comparison of five pulse sequences with variable slice thickness.

We used five MRI sequences in six patients with multiple sclerosis (MS): conventional spin-echo (CSE) with 5-mm slices; 2D fast spin-echo (FSE) with 2-mm slices; multishot T2*-weighted echo-planar imaging (EPI) with 5-mm slices; fast fluid-attenuated inversion recovery (fFLAIR) with 2-mm slices; and 3D fast spin-echo with 1.5-mm-thick slices. A total of 225 lesions were detected on CSE, 274 on 2D FSE, 137 on EPI, 385 on fFLAIR and 320 on 3D FSE. The EPI sequence was clearly the least sensitive and susceptibility artefact was a problem, particularly in the brain stem and temporal lobes. Fast FLAIR displayed a much higher number of supratentorial lesions (380) than 3D FSE (297), 2D FSE (264) or CSE (211). However, in the posterior cranial fossa 3D FSE was the most sensitive sequence (23 lesions), followed by CSE (14) and 2D FSE (10), while fFLAIR (5) was extremely insensitive.

Adult↗
PubMed1998

Secondary progressive multiple sclerosis: the relationship between short-term MRI activity and clinical features.

We report the findings in 60 patients with secondary progressive multiple sclerosis who had monthly brain MRI studies for 4 months (one baseline and three follow-up scans). The purpose was to define the short-term MRI natural history in a large cohort with secondary progressive disease and to ascertain its relationship with other clinical and MRI features. The patients were participating in either a natural history study or the placebo arm or non-treatment phase of a therapeutic trial. The cohort had clinical features typical of secondary progressive disease: thus, all had moderate or severe locomotor disabilities [Expanded Disability Status Scale (EDSS), score 3.5-8], with a median disease duration of 12 years. There was equal representation of males and females. During the 3 months of follow-up there was a total of 362 new enhancing lesions seen in 42 patients, and there were 24 relapses in 20 patients. There was no correlation between new enhancing lesions and age at study entry, age of disease onset, gender disease duration or EDSS, but there was a strong correlation with the number of enhancing lesions on the baseline scan (r = 0.65, P < 0.0001) and subsequent activity. There was a non-significant trend for higher numbers of new enhancing lesions in those having relapses during the 3 months of scanning (P = 0.14) or in the preceding 6 months (P = 0.06). The 34 patients who did not relapse in either period had significantly fewer new active lesions (P = 0.02) than those who relapsed at some stage during the 9 months. Nevertheless, considerable activity was seen in the non-relapsing cohorts: there was a mean of 3.5 (median 2) new enhancing lesions in those not relapsing during the 3 month study, and 5.5 (median 2) in those not relapsing in the previous 6 months. We conclude that short-term MRI activity is generally high in secondary progressive disease, confirming a useful role for the technique in exploratory trials. Further work should concentrate on elucidating the mechanisms of secondary progression by longer term follow-up studies of larger cohorts using multiple MRI and clinical measurements.

Adult↗
PubMed1998

Exploratory treatment trials in multiple sclerosis using MRI: sample size calculations for relapsing-remitting and secondary progressive subgroups using placebo controlled parallel groups.

OBJECTIVES: Serial brain MRI is widely used in pilot studies of new agents to monitor treatment efficacy in relapsing-remitting (RR) and secondary progressive (SP) multiple sclerosis (MS). For pilot trials, sample size calculations for the RR subgroup are based on the data from small numbers of patients and separate calculations for the SP subgroup have not been performed. The present study considers these issues. METHODS: The sample size calculations were based on data from six months of monthly T2 weighted and gadolinium enhanced MRI in 31 RR and 28 SP untreated patients undergoing natural history studies or in the placebo arm of a therapeutic trial. The calculations were for a placebo controlled, parallel groups design lasting six months. The sample sizes were based on bootstrap analysis with an 80% likelihood of showing a given treatment effect. RESULTS: With a single pretreatment scan, demonstration of a 70% reduction in newly active lesions required 2x30 RR and 2x50 SP patients. With an extra run-in scan one month before treatment, the sample sizes were 2x20 for RR and 2x30 for SP patients. CONCLUSIONS: The sample sizes required for RR patients were comparable with previous smaller studies. Larger sample sizes were needed for the SP group, but the extra run in scan resulted in a reduction in both groups. The larger sample sizes in the SPMS group were probably due to the combination of a higher proportion of patients with low MRI activity (< or =2 active MRI lesions in 50% of SP and 32% RR patients), as well as a few patients who displayed extremely high activity, thus increasing interpatient variability. These data should be considered in planning pilot MRI outcome trials.

Adult↗
PubMed1998

Three-dimensional fast fluid attenuated inversion recovery (3D fast FLAIR): a new MRI sequence which increases the detectable cerebral lesion load in multiple sclerosis.

Two-dimensional (2D) fluid attenuated inversion recovery (FLAIR) magnetic resonance imaging is superior to T2 weighted conventional spin echo (CSE), in certain areas of the brain but not in others, in detecting the lesions of multiple sclerosis (MS). The present study evaluates the ability of a recently developed three-dimensional fast FLAIR (3D fast FLAIR) sequence in detecting and quantifying the brain lesions of multiple sclerosis. The lesion volumes measured on the 3D fast FLAIR sequence with 1.5 mm thick slices were compared with those obtained from CSE brain images with 5 mm thick slices. The findings seen in 3D fast FLAIR brain images in 10 normal control subjects are also described. 3D fast FLAIR images showed an overall increase of 34% in lesion volume compared with CSE. The increase was most marked in the periventricular and "discrete" areas of the cerebral hemispheres. Lesion volumes seen in the subcortical areas were similar in both sequences. The CSE images displayed higher lesion volumes in the posterior cranial fossa. It is concluded that 3D fast FLAIR is a promising technique for quantifying cerebral pathology in MS which is not accessible to 2D CSE.

Adult↗
PubMed1998

The effect of section thickness on MR lesion detection and quantification in multiple sclerosis.

BACKGROUND AND PURPOSE: The purpose of our study was to investigate the effect of section thickness on MR detection of brain lesion volume and measurement precision in patients with multiple sclerosis (MS). METHODS: Eight subjects with known MS were studied on a 1.5-T MR system. We used a 3D fast fluid-attenuated inversion-recovery sequence to obtain contiguous axial brain images at section thicknesses of 5 mm, 3 mm, and 1 mm. Two sets of images were acquired at each section thickness during two sessions, between which the patient was removed from the scanner. Lesion volumes were measured at each section thickness using a semiautomated local thresholding technique. RESULTS: We found that progressive reduction in section thickness led to detection of smaller lesions, resulting in a significant (8%) increase in lesion volume on MR images as section thickness was reduced from 5 mm to 3 mm. However, despite a further increase in lesion detection at a section thickness of 1 mm, this did not result in an increase in total lesion volume. This finding indicates that the relationship between section thickness and lesion volume on MR images is not linear. Scan-rescan reproducibility was improved by reducing section thickness, at the cost of increased analysis time. CONCLUSION: This study shows that acquisition of very thin sections increases the sensitivity and precision of MS lesion measurement. Serial studies assessing lesion changes over time are needed to define the impact of this increase on sample size requirements for MS treatment trials.

Adult↗
PubMed1997

Improving interobserver variation in reporting gadolinium-enhanced MRI lesions in multiple sclerosis.

Gadolinium-enhanced MRI is a sensitive and objective means to monitor disease activity in multiple sclerosis (MS). We evaluated the interobserver agreement and the value of observer training in reporting enhancing lesions from serial MRI. Scans of 16 MS patients were evaluated by five inexperienced and five experienced observers before and after consensus formation and training. The number of lesions at baseline, and the number of new and persistent lesions at follow-up were scored. For each condition, weighted kappa values (kappa) and the mean average difference to the median (MADM) scores were calculated. Without training, the experienced readers showed good agreement on number of lesions at baseline and new lesions at follow-up, and moderate agreement for persistent lesions. The inexperienced readers showed poor agreement for baseline and persistent lesions, and moderate agreement for new lesions. After training, both groups reported lower absolute numbers of lesions, especially the inexperienced readers. The experienced readers showed good agreement for all lesion types, the inexperienced readers showed agreement for baseline and new lesions, and agreement was moderate for persistent lesions. In both groups MADM scores were < 0.72 for baseline and new lesions, but > 1.2 for persistent lesions. Interobserver agreement is improved by training, especially in inexperienced readers. Interobserver agreement in reporting gadolinium-enhanced lesions is high, which validates the use of serial, enhanced MRI as an outcome parameter in treatment trials in MS.

Analysis of Variance↗