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Abstract: The preferred vascular access for hemodialysis is an autologous arteriovenous fistula (AVF) in the arm: a surgically created connection between an artery and vein. The surgeon selects the AVF location based on experience and preoperative diagnostics. However, 20–50% of all lower arm AVFs are hampered by a too low access flow, whereas complications associated with too high flows are observed in 20% of all upper arm AVFs. We hypothesize that a pulse wave propagation model fed by patient-specific data has the ability to assist the surgeon in selecting the optimal AVF configuration by predicting direct postoperative flow. Previously, a 1D wave propagation model (spectral elements) was developed in which an approximated velocity profile was assumed based on boundary layer theory. In this study, we derived a distributed lumped parameter implementation of the pulse wave propagation model. The elements of the electrical analog for a segment are based on the approximated velocity profiles and dependent on the Womersley number. We present the application of the lumped parameter pulse wave propagation model to vascular access surgery and show how a patient-specific model is able to predict the hemodynamical impact of AVF creation and might assist in vascular access planning. The lumped parameter pulse wave propagation model was able to select the same AVF configuration as an experienced surgeon in nine out of ten patients. In addition, in six out of ten patients predicted postoperative flows were in the same order of magnitude as measured postoperative flows. Future research should quantify uncertainty in model predictions and measurements. [Copyright &y& Elsevier]

Aim: To compare the objective and subjective image quality of non-contrast three-dimensional (3D) navigator-gated balanced steady state free precession magnetic resonance angiography (NC-MRA) and contrast-enhanced magnetic resonance angiography (CE-MRA) along the entire thoracic aorta.Materials and Methods: Fifty consecutive patients with thoracic aortic disease underwent NC-MRA and CE-MRA using a 1.5 T MRI system. Vessel sharpness was assessed using signal intensity profiles at five predefined levels of the thoracic aorta. Two readers scored subjective quality. Manual diameter measurements of both readers were used for calculation of interobserver variation.Results: NC-MRA resulted in significantly sharper delineation of the aortic root, ascending aorta, and distal descending aorta compared to CE-MRA. Sharpness was comparable at the level of the arch and proximal descending aorta. NC-MRA resulted in significantly better subjective image quality. Interobserver agreement for diameter measurements was excellent for both techniques.Conclusion: NC-MRA resulted in superior image quality for assessment of the thoracic aorta and in better vessel sharpness for assessment of the aortic root and ascending aorta, when compared to CE-MRA. NC-MRA can be considered the MRA technique of choice for the assessment of the thoracic aorta diameters in clinical practice. [ABSTRACT FROM AUTHOR]