Steve Huntz Fung MD, Presenter: Nothing to Disclose

Christof Karmonik, Abstract Co-Author: Nothing to Disclose

Mario F. Dulay, Abstract Co-Author: Nothing to Disclose

Gustavo C. Roman, Abstract Co-Author: Nothing to Disclose

To evaluate test-retest reproducibility of cerebral blood flow (CBF) estimation from arterial spin labeling (ASL) in elderly patients evaluated for cognitive impairment, as part of longitudinal study assessing CBF changes over time in relationship to progression of disease and response to therapy.

Nineteen patients (ages 62-84, M:F 0.9) with cognitive impairment (including MCI, AD, PD, DLB, PPA, NPH, vascular and mixed dementia) had brain MRI using 3.0T clinical scanner. Pseudo-continuous ASL (pCASL) with post-labeling delay of 2.5 s was repeated within a 20 min imaging session, once in the beginning and again in the end of the imaging session after the patient was removed and repositioned back in the scanner to maximize real-world system-related errors while minimizing physiological fluctuations. High-resolution anatomical images were also obtained using SPGR for registration of M0 and CBF maps. FSL was used for image registration, gray matter (GM)/white matter (WM) segmentation, and image analysis. Reproducibility was evaluated by test-retest scatter plot, intraclass correlation coefficient (ICC), and within-subject coefficient of variation (wCV) calculations.

Figure shows test-retest scatter plots of GM and WM CBF values, demonstrating high correlation along line of identity. Scatter was slightly higher for tissues with lower CBF values (i.e. WM and some GM). Calculated ICC and wCV of GM and WM were comparable (GM ICC 0.88, WM ICC 0.84, GM wCV 10.6%, WM wCV 10.4%).

ASL is a reliable technique for estimating CBF even in elderly patients being evaluated for cognitive impairment, as these patients are more likely to have prolonged arterial transit times and suboptimal vessel geometry, which can confound CBF quantification using ASL. pCASL has relatively high precision, SNR, and insensitivity to vessel geometry, making it the preferred ASL technique for evaluating elderly patient population.

Knowing short-term test-retest reproducibility of ASL is essential for determining confidence limits in distinguishing true physiological changes from system-related errors in longitudinal CBF studies

Fung, S, Karmonik, C, Dulay, M, Roman, G, Test-Retest Reliability of Arterial Spin Labeling in Elderly Patients with Cognitive Impairment.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12036864.html