Ces radiol. 2018, 72(3):188-195 | DOI: 10.55095/CesRadiol2018/027

Impact of partial volume effect, noise, and region of interest selection on aortic flow evaluation using phase contrast MRIOriginal article

Radek Galabov, Jaroslav Tintěra, Lucie Súkupová

Základna radiodiagnostiky a intervenční radiologie IKEM, Praha

Objective: Phase contrast sequence may be used to measure the flux of blood in vessels. The result might be, however, corrupted by many errors including partial volume effect (PVE), region of interest (ROI) contouring, and noise. In this study we aim to quantify the error and if possible to suggest a proper strategy to minimize it.

Methods: Water flux was measured using a plastic flow phantom and changing the flow rate and spatial resolution which affects the PVE error. Signal-to-noise ratio (SNR) of magnitude images was used to estimate error caused by noise and a comparison to a statistical error from several measurements was made. Water flux in vitro and flux through aortal valve and sinotubular junction in vivo was also measured with undersized and oversized ROIs.

Results: The PVE subsides as spatial resolution improves and as the difference between magnitude signal from flowing and static tissue decreases. The error of flow through aortal valve was estimated to be 0.45%. Noise affects random error (estimation 0.05%) less then flow fluctuations (0.25%). The ROI size underestimation may lead to a severe underestimation of flow (over 10%) and a small underestimation in the case of aortal valve flow to a mild overestimation (5%). In general, an overestimation of ROI size is also erroneous (6%), although not as severe as underestimation.

Conclusion: The most relevant source of error out of the three sources examined is ROI contouring with overestimation being recommended over underestimation. The error resulting from the PVE is small compared to ROI contouring error. The error caused by noise is negligible compared to flow fluctuation.

Keywords: error, flow, magnetic resonance, phase contrast

Grants and funding:

Podpořeno z programového projektu Ministerstva zdravotnictví ČR s reg. č. 15-27178A.

Accepted: August 15, 2018; Published: September 1, 2018  Show citation