Chaudhary, UJ; (2008) Evaluation of a rating scale to investigate the presence and anatomical distribution of brain microbleeds in patients with cerebrovascular disease. Doctoral thesis , UCL (University College London).

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Abstract

Introduction: Brain microbleeds are small do- like well-defined areas of low signal intensity detectable on GRE T2*W MRI sequences because of the paramagnetic properties of blood breakdown products. Microbleeds are generally considered to range from 2 to 10 mm in size. Histologically they consist of deposits of hemosiderin laden macrophages. Microbleeds are reported both in healthy populations and patients with CVD. They are a risk factor for stroke and may be a marker of SVD including CAA and hypertensive small vessel vasculopathy. Microbleeds are also implicated in the development of cognitive dysfunction and focal neurological clinical symptoms. Perhaps the most important potential clinical question regarding microbleeds is whether they may help in predicting the risk of intracranial bleeding in patients on antithrombotic or thrombolytic treatment. To address all these questions a reliable rating scale is required. Objective: The purpose of this project is to determine intra and inter-rater agreement for the presence, number and anatomical distribution of microbleeds in a cohort of subjects with CVD, using a new rating scale, on two different GRE T2*W MRI sequences. Methods: Out of the initial cohort of 360 unselected, consecutive patients with suspected stroke, 303 patients were included and were divided into two groups based on different TE values for T2*W GRE MRI sequences (TE 40msec, N = 273 TE 26msec, N = 30). Both definite and possible microbleeds were identified, counted and anatomically categorized according to the rating scale by two trained, independent raters. Statistical analysis was performed on SPSS and ST AT A inter cooled. Results: The prevalence of microbleeds was 31 to 38%. Agreement for the presence of definite microbleeds in any location of the brain was good to very good (intra-rater K, = 0.87, inter-rater K, = 0.69). Agreement for the presence of definite microbleeds in the lobar, deep and infratentorial distribution and individual anatomical regions was also good to very good. Conclusion: This rating scale has good intra and inter-rater agreement for the presence of definite microbleeds in any location of the brain, including the lobar, deep and infratentorial areas and in individual anatomical regions, and should be validated in prospective and cross-sectional multicentre studies.

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