Visual Assessment of Atrophy on Magnetic Resonance Imaging in the Diagnosis of Pathologically Confirmed Young-Onset Dementias

Abstract

Objectives: To investigate the diagnostic accuracy of visual inspection of magnetic resonance imaging (MRI) in a range of pathologically confirmed diseases causing young-onset dementia and to assess the sensitivity and specificity of atrophy patterns for Alzheimer disease (AD) and frontotemporal lobar degeneration (FTLD). Design: Sixty-two patients with pathologically confirmed diseases that may present as young-onset dementia were selected from a biopsy and postmortem series. The first diagnostic T1-weighted volumetric MRI was obtained for each patient, together with images from 22 healthy control subjects. All MRIs were assessed for regional atrophy independently by 3 neuroradiologists, blinded to all clinical details except age. Observers were also asked to use their clinical judgment to form a diagnosis. Results: Eighty-seven percent of dementia cases were distinguished from controls after visual inspection of MRI, and a correct pathologically confirmed diagnosis was given in 58% of cases. Hippocampal atrophy was noted in 92% of AD cases but was commonly seen in other dementias and controls. A bilateral symmetrical pattern of hippocampal atrophy discriminated AD from FTLD with 47% specificity, while posterior greater than anterior gradient of atrophy was 92% specific for AD. Atrophy of the anterior, inferior, and lateral temporal lobes was suggestive of FTLD pathology (Ն90% sensitivity), while anterior greater than posterior gradient of atrophy and hemispheric asymmetry of atrophy were each at least 85% specific for FTLD. Conclusion: Despite variation and overlap of atrophy patterns, visual inspection of regional atrophy on MRI may aid in discriminating AD and FTLD.

Biomarkers for Alzheimer’s disease and other forms of dementia: Clinical needs, limitations and future aspects

“…For example, patients with amnestic MCI who converted to AD showed larger atrophy in several areas including hippocampus and inferior and middle temporal gyri, compared with non-converters (Chetelat et al, 2005). With the progression of AD, the corpus callosum usually appears atrophic anteriorly, differentiating this disease from FTLD, in which the posterior area of the corpus callosum is more affected (Likeman et al, 2005).…”

CSF neurogranin or tau distinguish typical and atypical Alzheimer disease

“…Given that synaptic dysfunction and neurodegeneration are common to a number of neurodegeneration diseases, the reason for this specificity is unclear. It might relate to the anatomical focus of the disease, noting that Ng is highly expressed in the amygdala, hippocampi and cortical regions,10, 11 areas typically and prominently involved in AD, although there is also prominent hippocampal involvement in some forms of frontotemporal dementia (FTD) 12. An alternative explanation is that it is specific to the pathological process that underpins AD.…”

Individual patient diagnosis of AD and FTD via high-dimensional pattern classification of MRI

“…Structural MRI has the potential to both aid diagnosis and provide objective surrogate markers of effects of pharmacological interventions designed to slow or halt the neurodegenerative process. Advanced image analysis methodologies have also been described in the literature, aiming to quantify structural characteristics of healthy individuals and patients with AD or FTD (Thompson, Mega et al 2001;Resnick, Pham et al 2003;Fox and Schott 2004;Grossman, McMillan et al 2004;Chang, Lomen-Hoerth et al 2005;Likeman, Anderson et al 2005;Short, Broderick et al 2005;Barnes, Whitwell et al 2006).…”