OBJECTIVE STENOSIS QUANTIFICATION FROM POSTSTENOTIC SIGNAL LOSS IN PHASE-CONTRAST MAGNETIC-RESONANCE ANGIOGRAPHIC DATASETS OF FLOW PHANTOMSAND RENAL-ARTERIES

In this study a semi-automated and observer-independent algorithm for quantifying post-stenotic signal loss (PSL) in three-dimensional phase -contrast (PC) magnetic resonance angiography (MRA) of patients with r enal artery stenosis is presented. This algorithm was developed on MRA datasets of stenotic phantoms, included in a flow circuit with statio nary flows. The length and the severity of the PSL (incorporating both the length and the degree of PSL) in the MRA datasets were proposed f or quantifying the stenoses. The algorithm was tested in renal arterie s; ten patients with renal artery stenosis and seven healthy volunteer s were investigated. Digital subtraction angiography was performed in the patients and served as the gold standard. Stenosis severity showed better correlation with the severity of the PSL than with the length, both for in vitro and in vivo measurements. Spearman correlation coef ficients (r(s)) showed statistically significant correlations between the severity of the PSL and parameters determined by digital subtracti on angiography, i.e., percent diameter stenosis (r(s) = 0.90). The len gth of the PSL showed no correlation with the diameter stenosis (r(s) = 0.37). In conclusion, this study presents a semi-automated and obser ver-independent way of quantifying signal loss, and the severity of th e PSL is proposed for quantifying stenoses, rather than the length of PSL. (C) 1998 Elsevier Science Inc.