Functional imaging of the dopamine transporter (I-123 Ioflupane) using SPECT might identify a defect in the nigrostriatal pathway that occurs in a variety of disorders including DLB and Parkinson disease. I-123 Ioflupane striatal activity tends to be normal in AD and low in DLB and Parkinson disease; however, AD and DLB can coexist in the same patient, potentially confounding results [11,51]. This is not a first-line imaging test but may be valuable after cross-sectional imaging to exclude other pathology. MR Spectroscopy Head There is sparse MR spectroscopy data on DLB. In one study [55], DLB patients were characterized by decreased NAA/Cr in the occipital voxel. AD patients were characterized by lower NAA/Cr in the frontal and posterior cingulate voxels. Normal NAA/Cr levels in the frontal voxel differentiated DLB patients with preserved hippocampal volumes from AD patients. MR spectroscopy abnormalities associated with loss of neuronal integrity localized to the occipital lobes in DLB, and the posterior cingulate gyri and frontal lobes in AD. The pattern of MR spectroscopy abnormalities may have a role in differential diagnosis of DLB and in distinguishing DLB patients with overlapping AD pathology. Although in the future, MR spectroscopy can provide additional useful information in the ante-mortem diagnosis of DLB; at present, its usefulness is limited. MRI functional (fMRI) Head Studies with fMRI show reduced activation of the occipital-temporal lobe regions during visual tasks. Resting state fMRI has demonstrated increased functional connectivity between the right posterior cingulate gyrus and other regions of the brain and reduced cortico-cortical connectivity. However, the diagnostic utility of fMRI for diagnosis of DLB has not been validated, and thus it cannot be recommended [56]. MRI Head Routine MRI head is performed to exclude other lesions like tumor or subdural hematoma. Contrast-enhanced MRI is not needed for initial evaluation.
Dementia. Functional imaging of the dopamine transporter (I-123 Ioflupane) using SPECT might identify a defect in the nigrostriatal pathway that occurs in a variety of disorders including DLB and Parkinson disease. I-123 Ioflupane striatal activity tends to be normal in AD and low in DLB and Parkinson disease; however, AD and DLB can coexist in the same patient, potentially confounding results [11,51]. This is not a first-line imaging test but may be valuable after cross-sectional imaging to exclude other pathology. MR Spectroscopy Head There is sparse MR spectroscopy data on DLB. In one study [55], DLB patients were characterized by decreased NAA/Cr in the occipital voxel. AD patients were characterized by lower NAA/Cr in the frontal and posterior cingulate voxels. Normal NAA/Cr levels in the frontal voxel differentiated DLB patients with preserved hippocampal volumes from AD patients. MR spectroscopy abnormalities associated with loss of neuronal integrity localized to the occipital lobes in DLB, and the posterior cingulate gyri and frontal lobes in AD. The pattern of MR spectroscopy abnormalities may have a role in differential diagnosis of DLB and in distinguishing DLB patients with overlapping AD pathology. Although in the future, MR spectroscopy can provide additional useful information in the ante-mortem diagnosis of DLB; at present, its usefulness is limited. MRI functional (fMRI) Head Studies with fMRI show reduced activation of the occipital-temporal lobe regions during visual tasks. Resting state fMRI has demonstrated increased functional connectivity between the right posterior cingulate gyrus and other regions of the brain and reduced cortico-cortical connectivity. However, the diagnostic utility of fMRI for diagnosis of DLB has not been validated, and thus it cannot be recommended [56]. MRI Head Routine MRI head is performed to exclude other lesions like tumor or subdural hematoma. Contrast-enhanced MRI is not needed for initial evaluation.