Noninvasive Assessment of Transstenotic Pressure Gradients in Porcine Renal Artery Stenoses by Using Vastly Undersampled Phase-Contrast MR Angiography

• Published in: Radiology Vol. 261; no. 1; pp. 266 - 273
• Main Authors: BLEY, Thorsten A, JOHNSON, Kevin M, FRANCOIS, Christopher J, REEDER, Scott B, SCHIEBLER, Mark L, LANDGRAF, Benjamin R, CONSIGNY, Daniel, GRIST, Thomas M, WIEBEN, Oliver
• Format: Journal Article
• Language: English
• Published: Oak Brook, IL Radiological Society of North America 01-10-2011; Radiological Society of North America, Inc
• Subjects: Animals; Biological and medical sciences; Cardiovascular system; Investigative techniques, diagnostic techniques (general aspects); Magnetic Resonance Angiography - methods; Medical sciences; Original Research; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Radiography; Renal Artery Obstruction - diagnostic imaging; Renal Artery Obstruction - physiopathology; Swine; Vertebrata; Mammalia; Renal artery; Phase contrast; Animal; Non invasive method; Medical imagery; Artiodactyla; NMR angiography; Nuclear magnetic resonance imaging; Ungulata; Pig
• ISSN: 0033-8419; 1527-1315
• DOI: 10.1148/radiol.11101175

To compare noninvasive transstenotic pressure gradient (TSPG) measurements derived from high-spatial- and temporal-resolution four-dimensional magnetic resonance (MR) flow measurements with invasive measurements obtained from endovascular pressure wires with digital subtraction angiographic guidance.
After Animal Care and Use Committee approval, bilateral renal artery stenosis (RAS) was created surgically in 12 swine. Respiratory-gated phase-contrast vastly undersampled isotropic projection (VIPR) MR angiography of the renal arteries was performed with a 1.5-T clinical MR system (repetition time, 11.4 msec; echo time [first echo], 3.7 msec; 18,000 projection angles; imaging volume, 260 × 260 × 200 mm; acquired isotropic spatial resolution, 1.0 × 1.0 × 1.0 mm; velocity encoding, 150 cm/sec). Velocities measured with phase-contrast VIPR were used to calculate TSPGs by using Navier-Stokes equations. These were compared with endovascular pressure measurements (mean and peak) performed by using fluoroscopic guidance with regression analysis.
In 19 renal arteries with an average stenosis of 62% (range, 0%-87%), there was excellent correlation between the noninvasive TSPG measurement with phase-contrast VIPR and invasive TSPG measurement for mean TSPG (R² = 95.4%) and strong correlation between noninvasive TSPG and invasive TSPG for the peak TSPG measures (R² = 82.6%). The phase-contrast VIPR-derived TSPG measures were slightly lower than the endovascular measurements. In four arteries with severe stenoses and one occlusion (mean, 86%; range, 75%-100%), the residual lumen within the stenosis was too small to determine TSPG with phase-contrast VIPR.
The unenhanced MR angiographic technique with phase-contrast VIPR allows for accurate noninvasive assessment of hemodynamic significance in a porcine model of RAS with highly accurate TSPG measurements.