PURPOSE: To investigate whether an existing method for correction of phase offset errors in phase-contrast velocity quantification is applicable for assessment of main pulmonary artery flow with an MR scanner equipped with a high-power gradient system. MATERIALS AND METHODS: The correction method consists of fitting a surface through the time average of stationary pixels of velocity-encoded phase images, and subtracting this surface from the velocity images. Pixels are regarded as stationary if their time standard deviation falls into the lowest percentile. Flow was measured in the main pulmonary artery of 15 subjects. Each measurement was repeated on a stationary phantom. The phase offset error in the phantom was used as a reference. Correction was applied with varying polynomial surface orders (0-5) and stationarity percentiles (5-50%). The optimal surface order and stationarity percentile were determined by comparing the fitted surface with the phantom. RESULTS: Using a first-order surface and a (noncritical) 25% percentile, the correction method significantly reduced the phase offset error from 1.1 to 0.35 cm/second (RMS), which is equivalent to a reduction from 11% to 3.3% of mean volume flow. Phase error correction strongly affected stroke volume (range -11 to 26%). CONCLUSION: The method significantly reduces phase offset errors in pulmonary artery flow.
PURPOSE: To investigate whether an existing method for correction of phase offset errors in phase-contrast velocity quantification is applicable for assessment of main pulmonary artery flow with an MR scanner equipped with a high-power gradient system. MATERIALS AND METHODS: The correction method consists of fitting a surface through the time average of stationary pixels of velocity-encoded phase images, and subtracting this surface from the velocity images. Pixels are regarded as stationary if their time standard deviation falls into the lowest percentile. Flow was measured in the main pulmonary artery of 15 subjects. Each measurement was repeated on a stationary phantom. The phase offset error in the phantom was used as a reference. Correction was applied with varying polynomial surface orders (0-5) and stationarity percentiles (5-50%). The optimal surface order and stationarity percentile were determined by comparing the fitted surface with the phantom. RESULTS: Using a first-order surface and a (noncritical) 25% percentile, the correction method significantly reduced the phase offset error from 1.1 to 0.35 cm/second (RMS), which is equivalent to a reduction from 11% to 3.3% of mean volume flow. Phase error correction strongly affected stroke volume (range -11 to 26%). CONCLUSION: The method significantly reduces phase offset errors in pulmonary artery flow.
Authors: Emilie Bollache; Pim van Ooij; Alex Powell; James Carr; Michael Markl; Alex J Barker Journal: Int J Cardiovasc Imaging Date: 2016-07-19 Impact factor: 2.357
Authors: Florian Schuchardt; Laure Schroeder; Constantin Anastasopoulos; Michael Markl; Jochen Bäuerle; Anja Hennemuth; Johann Drexl; José M Valdueza; Irina Mader; Andreas Harloff Journal: Eur Radiol Date: 2015-02-01 Impact factor: 5.315
Authors: Erik J Offerman; Ioannis Koktzoglou; Christopher Glielmi; Anindya Sen; Robert R Edelman Journal: Magn Reson Med Date: 2012-03-05 Impact factor: 4.668
Authors: Peter D Gatehouse; Marijn P Rolf; Martin J Graves; Mark Bm Hofman; John Totman; Beat Werner; Rebecca A Quest; Yingmin Liu; Jochen von Spiczak; Matthias Dieringer; David N Firmin; Albert van Rossum; Massimo Lombardi; Juerg Schwitter; Jeanette Schulz-Menger; Philip J Kilner Journal: J Cardiovasc Magn Reson Date: 2010-01-14 Impact factor: 5.364
Authors: Philip J Kilner; Tal Geva; Harald Kaemmerer; Pedro T Trindade; Juerg Schwitter; Gary D Webb Journal: Eur Heart J Date: 2010-01-11 Impact factor: 29.983