Evaluation of measures of technical image quality for intracranial magnetic resonance angiography

We evaluate three measures of technical image quality for intracranial magn etic resonance angiography (MRA): (1) a two-alternative forced choice (2AFC ) evaluation of vessel visibility, (2) vessel-to-background signal-differen ce-to-noise ratio (SDNR), and (3) observer ranking of the fidelity of vesse l morphology compared to that in a gold standard image. The gold standard u sed for both the 2AFC and ranking measures is intraarterial catheter angiog raphy. These measures are applied to healthy arterial segments. The 2AFC an d SDNR measures directly evaluate the visibility of artery segments for whi ch the existence is known from the gold standard images. We argue that (1) 2AFC evaluates the carrier signals on which any vascular disease process is modulated and provides an upper bound on the detectibility of vascular les ions, (2) SDNR is a predictor of 2AFC, and (3) ranking may be used to predi ct the relative performance of techniques in the detection of vascular lesi ons. (C) 1999 Academic Press.