Can MRI Visual Assessment Differentiate the Variants of Primary-Progressive Aphasia?
OBJECTIVE
Primary-progressive aphasia is a clinically and pathologically heterogeneous condition. Nonfluent, semantic, and logopenic are the currently recognized clinical variants. The recommendations for the classification of primary-progressive aphasia have advocated variant-specific patterns of atrophy. The aims of the present study were to evaluate the sensitivity and specificity of the proposed imaging criteria and to assess the intra- and interrater reporting agreements.


METHODS
The cohort comprised 51 patients with a root diagnosis of primary-progressive aphasia, 25 patients with typical Alzheimer disease, and 26 matched control participants. Group-level analysis (voxel-based morphometry) confirmed the proposed atrophy patterns for the 3 syndromes. The individual T1-weighted anatomic images were reported by 3 senior neuroradiologists.


RESULTS
We observed a dichotomized pattern of high sensitivity (92%) and specificity (93%) for the proposed atrophy pattern of semantic-variant primary-progressive aphasia and low sensitivity (21% for nonfluent-variant primary-progressive aphasia and 43% for logopenic-variant primary-progressive aphasia) but high specificity (91% for nonfluent-variant primary-progressive aphasia and 95% for logopenic-variant primary-progressive aphasia) in other primary-progressive aphasia variants and Alzheimer disease (sensitivity 43%, specificity 92%). MR imaging was least sensitive for the diagnosis of nonfluent-variant primary-progressive aphasia. Intrarater agreement analysis showed mean κ values above the widely accepted threshold of 0.6 (mean, 0.63 ± 0.16). Pair-wise interobserver agreement outcomes, however, were well below this threshold in 5 of the 6 possible interrater contrasts (mean, 0.41 ± 0.09).


CONCLUSIONS
While the group-level results were in precise agreement with the recommendations, semantic-variant primary-progressive aphasia was the only subtype for which the proposed recommendations were both sensitive and specific at an individual level.
From the Department of Neurology (S.A.S.), University of California, Irvine, Irvine, California ssajjadi@uci.edu.
S A
http://orcid.org/0000-0002-8960-2213
SA
Sajjadi
Department of Radiology (N.S.-B., J.H.G.), University of Cambridge, Cambridge, UK.|Department of Radiology (N.S.-.B., J.C., J.H.G., D.S.), Cambridge University Hospitals, Cambridge, UK.
N
http://orcid.org/0000-0001-7029-7215
N
Sheikh-Bahaei
Department of Radiology (N.S.-.B., J.C., J.H.G., D.S.), Cambridge University Hospitals, Cambridge, UK.
J
http://orcid.org/0000-0002-9163-3318
J
Cross
Department of Radiology (N.S.-B., J.H.G.), University of Cambridge, Cambridge, UK.|Department of Radiology (N.S.-.B., J.C., J.H.G., D.S.), Cambridge University Hospitals, Cambridge, UK.
J H
http://orcid.org/0000-0003-4787-8091
JH
Gillard
Department of Radiology (N.S.-.B., J.C., J.H.G., D.S.), Cambridge University Hospitals, Cambridge, UK.
D
http://orcid.org/0000-0002-0220-853X
D
Scoffings
German Center for Neurodegenerative Diseases (P.J.N.), Magdeburg, Germany.
P J
http://orcid.org/0000-0002-5860-5921
PJ
Nestor
D000368:Aged; D018888:Aphasia, Primary Progressive / Q000000981:diagnostic imaging*; D001921:Brain / Q000000981:diagnostic imaging*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging / Q000379:methods*; D012680:Sensitivity and Specificity