Evidence of bilateral temporal lobe involvement in primary progressive aphasia: a SPECT study.
Primary progressive aphasia (PPA) is rare. Only limited series have been reported with SPECT or PET. Moreover, in the majority of studies, the left-to-right asymmetry ratio was used, leading to difficulties in right hemisphere analyzes.


METHODS
Twenty-nine patients with clinical criteria of PPA (Mesulam and Weintraub) were included and compared with 12 control subjects. Complete language examination was performed in all patients. SPECT was performed on a double-head gamma camera after intravenous injection of hexamethylpropyleneamine oxime (22 patients and 12 control subjects) or ethylcysteinate dimer (7 patients). Nineteen regions of interest (ROIs) were drawn on each hemisphere in all patients using the Talairach atlas. The perfusion index (PI = cortex-to-cerebellum ratio) was calculated for each ROI. Atrophy was quantified on MRI by consensus of 3 observers in 16 cortical ROIs. ANOVAs were used to compare the PI between (a). patients and control subjects, (b). patients with (n = 15) or without (n = 14) lexicosemantic abnormalities (LS+ vs. LS-) and patients with (n = 19) or without (n = 10) arthric disorders (A+ vs. A-), and (c). patients with or without atrophy.


RESULTS
In the 29 patients, the PI was significantly lower in the left temporopolar, left lateral temporal, left Wernicke, left parietal, and right lateral temporal cortex when compared with control subjects (P < 0.001). In LS+ patients versus control subjects, the PI significantly decreased in the left temporal cortex (lateral temporal; medial temporal; temporopolar; Wernicke), left Broca, left parietal, and right lateral temporal cortex (P < 0.001). In addition, LS+ versus LS- comparison showed a significant decrease in the left lateral, left medial temporal, and left Broca cortex (P < 0.001). In comparison with control subjects, the PI was not significantly different in A+ patients, whereas in A- patients the PI was significantly decreased in the left and right lateral temporal cortex, left Wernicke, and left parietal cortex. Moreover, the PI significantly decreased in the left lateral temporal region in A+ patients compared with A- patients. Finally, in patients without atrophy, the PI significantly decreased in the right and left lateral temporal cortex and the left parietal cortex (P < 0.01).


CONCLUSIONS
Our study demonstrates that right-handed patients with PPA present a decreased perfusion in the bilateral temporal cortex. Moreover, in these regions, morphologic abnormalities are preceded by perfusion abnormalities. Finally, our results show that large left temporal dysfunction occurs in patients with LS disorders.
Soriani-Lefèvre
Marie-Hélène
MH
Department of Nuclear Medicine, Rouen University Hospital, Henri Becquerel Center, Laboratoire Universitaire Quantification en Imagerie Fonctionnelle, Rouen, France.
Hannequin
Didier
D
Bakchine
Serge
S
Ménard
Jean-François
JF
Manrique
Alain
A
Hitzel
Anne
A
Kotzki
Pierre-Olivier
PO
Boudousq
Vincent
V
Vera
Pierre
P
D000368:Aged; D018888:Aphasia, Primary Progressive / Q000150:complications / Q000175:diagnosis / Q000000981:diagnostic imaging*; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D003545:Cysteine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007806:Language Disorders / Q000150:complications / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013064:Speech Disorders / Q000150:complications / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000378:metabolism; D019690:Technetium Tc 99m Exametazime / Q000493:pharmacokinetics; D013702:Temporal Lobe / Q000000981:diagnostic imaging* / Q000378:metabolism; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime; C059659:technetium Tc 99m bicisate; D003545:Cysteine