TY - JOUR
T1 - A tri-exponential model for intravoxel incoherent motion analysis of the human kidney
T2 - In silico and during pharmacological renal perfusion modulation
AU - van der Bel, René
AU - Gurney-Champion, Oliver J.
AU - Froeling, Martijn
AU - Stroes, Erik S.G.
AU - Nederveen, Aart J.
AU - Krediet, C. T.Paul
N1 - Funding Information:
This project was funded by the Dutch Kidney Foundation (Project KJPB 12.029 to CTPK). CTPK is supported by the Netherlands Organization for Health Research (Clinical Fellowship 40007039712461). This support is gratefully acknowledged.
Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2017/6
Y1 - 2017/6
N2 - In the kidneys, there is both blood flow through the capillaries and flow of pre-urine through the tubuli and collecting ducts. We hypothesized that diffusion-weighted (DW) MRI measures both blood and pre-urine flow when using a tri-exponential intravoxel incoherent motion (IVIM) model. Our aim was to systematically investigate and optimize tri-exponential IVIM-analysis for the kidney and test its sensitivity to renal perfusion changes in humans. The tri-exponential fit probes the diffusion coefficient (D), the intermediate (D*i) and fast (D*f) pseudo-diffusion coefficients, and their signal fractions, fD, fi and ff. First, we studied the effects of fixing the D*-coefficients of the tri-exponential fit using in silico simulations. Then, using a 3T MRI scanner, DW images were acquired in healthy subjects (18–24 years) and we assessed the within-subject coefficient of variation (wsCV, n = 6). Then, renal perfusion was modulated by Angiotensin II infusion during which DW imaging of the kidneys and phase contrast MRI of the renal artery was performed (n = 8). Radioisotope clearing tests were used to assess the glomerular filtration rate. Simulations showed that fixing the D*-coefficients - which could potentially increase the fit stability - in fact decreased the precision of the model. Changes in D*-coefficients were translated into the f-parameters instead. Fixing D*-coefficients resulted in a stronger response of the fit parameters to the intervention. Using this model, the wsCVs for D, fD, fi and ff were 2.4%, 0.8%, 3.5%, 19.4% respectively. fi decreased by 14% (p = 0.059) and ff increased by 32% (p = 0.004) between baseline and maximal Angiotensin II dose. ff inversely correlated to renal plasma flow (R = −0.70, p i correlated to glomerular filtration rate (R = 0.39, p = 0.026). We validated a kidney-specific method for IVIM analysis using a tri-exponential model. The model is able to track renal perfusion changes induced by Angiotensin II.
AB - In the kidneys, there is both blood flow through the capillaries and flow of pre-urine through the tubuli and collecting ducts. We hypothesized that diffusion-weighted (DW) MRI measures both blood and pre-urine flow when using a tri-exponential intravoxel incoherent motion (IVIM) model. Our aim was to systematically investigate and optimize tri-exponential IVIM-analysis for the kidney and test its sensitivity to renal perfusion changes in humans. The tri-exponential fit probes the diffusion coefficient (D), the intermediate (D*i) and fast (D*f) pseudo-diffusion coefficients, and their signal fractions, fD, fi and ff. First, we studied the effects of fixing the D*-coefficients of the tri-exponential fit using in silico simulations. Then, using a 3T MRI scanner, DW images were acquired in healthy subjects (18–24 years) and we assessed the within-subject coefficient of variation (wsCV, n = 6). Then, renal perfusion was modulated by Angiotensin II infusion during which DW imaging of the kidneys and phase contrast MRI of the renal artery was performed (n = 8). Radioisotope clearing tests were used to assess the glomerular filtration rate. Simulations showed that fixing the D*-coefficients - which could potentially increase the fit stability - in fact decreased the precision of the model. Changes in D*-coefficients were translated into the f-parameters instead. Fixing D*-coefficients resulted in a stronger response of the fit parameters to the intervention. Using this model, the wsCVs for D, fD, fi and ff were 2.4%, 0.8%, 3.5%, 19.4% respectively. fi decreased by 14% (p = 0.059) and ff increased by 32% (p = 0.004) between baseline and maximal Angiotensin II dose. ff inversely correlated to renal plasma flow (R = −0.70, p i correlated to glomerular filtration rate (R = 0.39, p = 0.026). We validated a kidney-specific method for IVIM analysis using a tri-exponential model. The model is able to track renal perfusion changes induced by Angiotensin II.
KW - Angiotensin II
KW - Diffusion-weighted imaging
KW - Functional imaging
KW - Intravoxel incoherent motion
KW - Kidney
KW - Magnetic resonance imaging
KW - Perfusion
UR - http://www.scopus.com/inward/record.url?scp=85018408300&partnerID=8YFLogxK
U2 - 10.1016/j.ejrad.2017.03.008
DO - 10.1016/j.ejrad.2017.03.008
M3 - Article
C2 - 28629565
AN - SCOPUS:85018408300
SN - 0720-048X
VL - 91
SP - 168
EP - 174
JO - European Journal of Radiology
JF - European Journal of Radiology
ER -