Distinct cerebral perfusion patterns in FTLD and AD

Abstract

Objective: We examined the utility of distinguishing between patients with frontotemporal lobar degeneration (FTLD) and Alzheimer disease (AD) using quantitative cerebral blood flow (CBF) imaging with arterial spin labeled (ASL) perfusion MRI.

Methods: Forty-two patients with FTLD and 18 patients with AD, defined by autopsy or CSF-derived biomarkers for AD, and 23 matched controls were imaged with a continuous ASL method to quantify CBF maps covering the entire brain.

Results: Patients with FTLD and AD showed distinct patterns of hypoperfusion and hyperperfusion. Compared with controls, patients with FTLD showed significant hypoperfusion in regions of the frontal lobe bilaterally, and hyperperfusion in posterior cingulate and medial parietal/precuneus regions. Compared with controls, patients with AD showed significant hypoperfusion in the medial parietal/precuneus and lateral parietal cortex, and hyperperfusion in regions of the frontal lobe. Direct comparison of patient groups showed significant inferior, medial, and dorsolateral frontal hypoperfusion in FTLD, and significant hypoperfusion in bilateral lateral temporal-parietal and medial parietal/precuneus regions in AD.

Conclusions: Doubly dissociated areas of hypoperfusion in FTLD and AD are consistent with areas of significant histopathologic burden in these groups. ASL is a potentially useful biomarker for distinguishing patients with these neurodegenerative diseases.

Figures

Figure 1 Statistical parametric map of significant cerebral blood flow differences between patients and controls (A) Patients with frontotemporal lobar degeneration (FTLD). The significance level used for thresholding the maps in A was p < 0.005 (t >2.66, uncorrected). Green = hypoperfusion and purple = hyperperfusion in FTLD. (B) Patients with Alzheimer disease (AD). The significance level used for thresholding the maps in B was p < 0.05 (t >3.4, with false discovery rate correction). Turquoise = hypoperfusion and red = hyperperfusion in AD.

Figure 2 Statistical parametric map of significant cerebral blood flow differences between patients with FTLD and AD The significance level used for thresholding the statistical parametric map is p < 0.05 (t >3.2, with false discovery rate correction). Yellow indicates significantly reduced perfusion in Alzheimer disease (AD) compared with frontotemporal lobar degeneration (FTLD); blue indicates significantly reduced perfusion in FTLD compared with AD.