Essence of ADC Values in Leukoaraiosis Imaging and Association of Leukoaraiosis with Cognitive Dysfunction

Introduction: Leukoaraiosis is a common cerebral white matter disease identified radiologically as discrete focal or diffuse patchy bilateral hypodense on computed tomography and hyperintense on T2 weighted Resonance Imaging. Underlying pathogenesis and clinical essence of this radiological finding is yet to be defined clearly. Some patients present with impairment of cognition and dementia. Aim: To assess the usefulness of ADC values in grading the leukoaraiosis and defining its complete extent, identification of the normal appearing white matter with early demyelination changes which is not detectable on conventional MRI and to evaluate the association of leukoaraiosis with impaired cognition. Materials and Methods: This prospective study was done at MRI unit of Department of Radiodiagnosis, C.S.M. Medical University, Lucknow, India during a period of one year from August 2007 to July 2008. Study comprised of Group 1 (cases, n-60) with leukoaraiosis and Group 2 (controls, n-20), healthy subjects with no leukoaraiosis both above 50 years of age. All subjects were studied with 1.5T MRI machine, ADCav values of leukoaraiosis lesions and normal white matter (WM) were estimated. Results: The ADCav values of the leukoaraiotic regions were higher than the normal white matter and the values proportionately increased with the grade of the lesions (p-value ≤ 0.001). The ADCav values of normal white matter were higher in cases than controls and the values increased with grade of leukoaraiosis (p-value < 0.001). Significant association found between reduced Mini Mental Status Examination (MMSE) and presence of leukoaraiosis (p-value ≤ 0.001) and proportional reduction of MMSE score with increasing grade of leukoaraiosis (p-value ≤ 0.001). Conclusions: Increasing ADC values of leukoaraiosis lesions with increasing grade could be used as a grading scale of leukoaraiosis. Higher ADCav values of normal white matter in patients with leukoaraiosis which were increasing with higher grades of leukoaraiosis, is probably representing those areas that are prone to develop leukoaraiosis over time and hence help in assessment of complete extent of the lesion. The significant association of leukoaraiosis with impaired cognition, proposes leukoaraiosis as one of the cause for cognitive function.