ORIGINAL RESEARCH n TECHNICAL DEVELOPMENTS 858 radiology.rsna.org n Radiology: Volume 268: Number 3—September 2013 Measurement of Tissue Interstitial Volume in Healthy Patients and Those with Amyloidosis with Equilibrium Contrast-enhanced MR Imaging 1 Steve Bandula, MA, MB, BChir Sanjay M. Banypersad, MBChB Daniel Sado, BM, BSc Andrew S. Flett, MD Shonit Punwani, PhD Stuart A. Taylor, MD Philip N. Hawkins, FMedSci James C. Moon, MD Purpose: To investigate equilibrium contrast material–enhanced magnetic resonance (MR) imaging measurement of ex- tracellular volume (ECV) fraction within healthy abdomi- nal tissues and to test the hypotheses that tissue ECV in systemic amyloid light-chain (AL) amyloidosis is greater than in healthy patients and show that this increase corre- lates with organ amyloid burden. Materials and Methods: A local ethics committee approved the study and all pa- tients gave written informed consent. Forty healthy vol- unteers (18 men, 22 women; median age, 43 years; age range, 24–88 years) and 67 patients with AL amyloidosis (43 men, 24 women; median age, 65 years; age range, 38–81 years) underwent equilibrium MR imaging of the upper abdomen. ECV was measured in the liver, spleen, and paravertebral muscle. Patients with amyloidosis also underwent serum amyloid P (SAP) component scintigra- phy so that specific organ involvement by amyloid could be scored. Variation in ECV between tissues was assessed by using a Friedman Test. Tissue ECV in healthy and amy- loidosis groups were compared by using a Mann-Whitney U test. Spearman correlation was used to test for an asso- ciation between the organ SAP score and ECV. Results: ECV measured at equilibrium MR imaging varied signifi- cantly between organs in healthy volunteers (x 2 = 31.0; P , .001). ECV was highest in the spleen (0.34), followed by liver (0.29) and muscle (0.09). ECVs measured within the spleen (0.39; P, .001), liver (0.31; P = .005), and muscle (0.16; P, .001) were significantly higher in pa- tients with amyloidosis than in healthy control subjects. ECV measured in the liver and spleen showed increas- ing organ amyloid burden assessed at SAP scintigraphy (liver, r s = 0.54; spleen, r s = 0.57). Conclusion: Equilibrium MR imaging can be used to define ECV within healthy tissues. ECV is increased in amyloidosis compared with healthy tissues, and this increase correlates with ris- ing tissue amyloid burden. q RSNA, 2013 Supplemental material: http://radiology.rsna.org/lookup /suppl/doi:10.1148/radiol.13121889/-/DC1 1 From the Centre for Medical Imaging (S.B., S.P., S.A.T.), Institute of Cardiovascular Science (S.M.B., J.C.M.), and Centre for Amyloidosis and Acute Phase Proteins (P.N.H.), University College London, London, England; and University College London Hospital, London, England (S.B., S.M.B., D.S., A.S.F., S.P., S.A.T., J.C.M.). Received September 10, 2012; revision requested November 5; revision received December 23; accepted January 25, 2013; final version accepted February 13. This work was undertaken at the Comprehensive Biomedical Research Centre, University College Hospital London, which received a proportion of the funding from the National Institute for Health Research. S.B. supported by a doctoral fellowship from the National Institute for Health Research, UK. Address correspondence to J.C.M., The Heart Hospital, 16-18 Westmoreland St, Lon- don W1G 8PH, England (e-mail: james.moon@uclh.nhs.uk). The views expressed in this publication are those of the authors and not necessarily those of the UK Department of Health. q RSNA, 2013 Note: This copy is for your personal non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, contact us at www.rsna.org/rsnarights.