Fig 1.
DWI = diffusion-weighted imaging.
Table 1.
Diagnostic yield of diffusion-weighted imaging in patients with cognitive impairment and clinical characteristics of patients with positive findings.
Fig 2.
Exemplary diagnoses of recent small subcortical infarct, transient global amnesia, Creutzfeldt-Jakob disease, encephalitis and lymphoma made on diffusion-weighted imaging.
(a) A 62 year old man with memory impairment since one year ago was subsequently diagnosed with vascular dementia. Axial diffusion-weighted image (left, b value = 1000 sec/mm2, slice thickness/gap, 2/0 mm) showed a tiny diffusion restricted lesion in the right paracentral lobule suggesting a recent small subcortical infarct (arrow). There was hyperintensity in the corresponding area (arrow) on the axial fluid-attenuated inversion recovery image (right), which was indistinguishable from white matter hyperintensity due to severe small vessel disease. (b) A 50 year old man with a history of transient memory impairment was subsequently diagnosed with transient global amnesia. Axial, diffusion-weighted image (left, b value = 1000 sec/mm2, slice thickness/gap, 2/0 mm) showed a tiny diffusion restricted lesion in the right hippocampus (arrow). This lesion was not demonstrable in the corresponding area (arrow) on the axial fluid-attenuated inversion recovery image (right). (c) A 63 year old woman who presented with rapidly progressive memory decline was subsequently diagnosed with Creutzfeldt-Jakob disease. Axial, diffusion-weighted image (left, b value = 1000 sec/mm2, slice thickness/gap, 2/0 mm) showed diffuse cortical diffusion restriction in bilateral parietal lobes (arrows) with subtle hyperintensity in the corresponding area (arrows) on the axial fluid-attenuated inversion recovery image (right). (d) A 50 year old woman who reported memory impairment following bone marrow transplantation for myelodysplastic syndrome was subsequently diagnosed as encephalitis on multidisciplinary consensus. Axial diffusion-weighted image (left, b value = 1000 sec/mm2, slice thickness/gap, 2/0 mm) showed diffusion restriction in bilateral medial temporal lobes (arrows), with subtle hyperintensity in the corresponding area (arrows) on the axial fluid-attenuated inversion recovery image (right). (e) A 75 year old man who presented with progressive memory impairment was subsequently diagnosed as diffuse large B cell lymphoma on stereotactic biopsy. Axial diffusion-weighted image (left, b value = 1000 sec/mm2, slice thickness/gap, 2/0 mm) showed diffusion restriction associated with a mass-like lesion involving the splenium of the corpus callosum that was hyperintense with perilesional edema on the axial fluid-attenuated inversion recovery image (right).
Table 2.
Diagnostic yield of diffusion-weighted imaging in patients with cognitive impairment by age groups and sex.
Fig 3.