Morbelli Silvia, Ferrara Michela, Fiz Francesco, Dessi Barbara, Arnaldi Dario, Picco Agnese, Bossert Irene, Buschiazzo Ambra, Accardo Jennifer, Picori Lorena, Girtler Nicola, Mandich Paola, Pagani Marco, Sambuceti Gianmario, Nobili Flavio
Nuclear Medicine Unit, Department of Health Science (DISSAL), University of Genoa and IRCCS AOU San Martino-IST, Largo R. Benzi 10, 16132, Genoa, Italy.
Clinical Neurology, Department of Neuroscience (DINOGMI), University of Genoa and IRCCS AOU San Martino-IST, Genoa, Italy.
Eur J Nucl Med Mol Imaging. 2016 Jul;43(7):1337-47. doi: 10.1007/s00259-016-3335-3. Epub 2016 Mar 1.
The diagnosis of behavioural variant frontotemporal dementia (bvFTD) is challenging during the predementia stage when symptoms are subtle and confounding. Morphological and functional neuroimaging can be particularly helpful during this stage but few data are available.
We retrospectively selected 25 patients with late-onset probable bvFTD. Brain structural MRI and FDG PET were performed during the predementia stage (mean MMSE score 27.1 ± 2.5) on average 2 years before. The findings with the two imaging modalities were compared (SPM8) with those in a group of 20 healthy subjects. The bvFTD patients were divided into two subgroups: those with predominant disinhibition (bvFTD+) and those with apathy (bvFTD-).
Hypometabolism exceeded grey matter (GM) density reduction in terms of both extension and statistical significance in all comparisons. In the whole bvFTD group, hypometabolism involved the bilateral medial, inferior and superior lateral frontal cortex, anterior cingulate, left temporal and right parietal cortices and the caudate nuclei. GM density reduction was limited to the right frontal cortex and the left medial temporal lobe. In bvFTD+ patients hypometabolism was found in the bilateral medial and basal frontal cortex, while GM reduction involved the left anterior cingulate and left inferior frontal cortices, and the right insula. In bvFTD- patients, atrophy and mainly hypometabolism involved the lateral frontal cortex and the inferior parietal lobule.
These findings suggest that hypometabolism is more extensive than, and thus probably precedes, atrophy in predementia late-onset bvFTD, underscoring different topographic involvement in disinhibited and apathetic presentations. If confirmed in a larger series, these results should prompt biomarker operationalization in bvFTD, especially for patient selection in therapeutic clinical trials.
行为变异型额颞叶痴呆（bvFTD）在痴呆前期的诊断具有挑战性，因为此时症状较为隐匿且容易混淆。形态学和功能神经影像学检查在此阶段可能会特别有帮助，但相关数据较少。
我们回顾性选取了25例晚发型可能的bvFTD患者。在痴呆前期（平均简易精神状态检查表（MMSE）评分27.1±2.5）平均2年前进行了脑结构磁共振成像（MRI）和氟代脱氧葡萄糖正电子发射断层显像（FDG PET）检查。将这两种成像方式的检查结果与20名健康受试者组成的对照组进行比较（使用统计参数映射8（SPM8）软件）。bvFTD患者被分为两个亚组：以脱抑制为主的患者（bvFTD+）和以淡漠为主的患者（bvFTD-）。
在所有比较中，无论是在范围还是统计学意义上，代谢减低均超过了灰质密度降低。在整个bvFTD组中，代谢减低涉及双侧内侧、下部和上部外侧额叶皮质、前扣带回、左侧颞叶和右侧顶叶皮质以及尾状核。灰质密度降低仅限于右侧额叶皮质和左侧内侧颞叶。在bvFTD+患者中，双侧内侧和基底额叶皮质出现代谢减低，而灰质减少涉及左侧前扣带回、左侧下部额叶皮质和右侧岛叶。在bvFTD-患者中，萎缩以及主要是代谢减低涉及外侧额叶皮质和顶下小叶。
这些发现表明，在痴呆前期晚发型bvFTD中，代谢减低比萎缩更广泛，因此可能先于萎缩出现，这突出了脱抑制和淡漠表现中不同的部位受累情况。如果在更大规模的研究中得到证实，这些结果应促使在bvFTD中进行生物标志物的应用，特别是在治疗性临床试验中用于患者选择。
