Diagnostic patterns of regional atrophy on MRI and regional cerebral blood flow change on SPECT in young onset patients with Alzheimer's disease, frontotemporal dementia and vascular dementia.
OBJECTIVE
Alzheimer's disease (AD), frontotemporal dementia (FTD) and vascular dementia (VaD) are the three most common causes of young onset dementias. Most neuroimaging studies of these disorders have involved comparisons with normal controls. The aims of this study were to examine the clinical diagnostic value of magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) (in combination and in isolation) in the differentiation of one form of dementia from another from amongst a group of AD, FTD and VaD.


METHODS
T1 weighted MRI images and 99mTc-HMPAO SPECT images were obtained from consecutive patients with FTD (n=21), AD (n=23) and VaD (n=20) and rated visually by experienced neuroradiologists and nuclear medicine physicians.


RESULTS
Asymmetrical atrophy was seen only in FTD. Frontotemporal dementia patients were the most atrophic whereas severe atrophy was rarely observed in VaD. Severe frontal atrophy (unilaterally or bilaterally) and/or asymmetrical atrophy on MRI is highly diagnostic (sensitivity 0.71, specificity 0.93, LR 10.24) of FTD from within a group of FTD and non-FTD (AD, VaD) patients. Mild or severe parietal atrophy with severe reduction in parietal regional cerebral blood flow on SPECT is diagnostic (sensitivity 0.71, specificity 0.76, LR 3.02) of AD from within a group of AD and non-AD (VaD, FTD) patients.


CONCLUSIONS
Anatomical (MRI) and functional (SPECT) imaging provide different information and a combination of these modalities improves diagnostic specificity.
Varma
A R
AR
Cerebral Function Unit, Neurology Department, Manchester Royal Infirmary, Central Manchester Healthcare Trust, Manchester, UK. anoop.varma@btinternet.com
Adams
W
W
Lloyd
J J
JJ
Carson
K J
KJ
Snowden
J S
JS
Testa
H J
HJ
Jackson
A
A
Neary
D
D
D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D001284:Atrophy; D002560:Cerebrovascular Circulation; D003704:Dementia / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D015140:Dementia, Vascular / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010296:Parietal Lobe / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D015899:Tomography, Emission-Computed, Single-Photon