Quantification of Femoral Perfusion via DCE-MRI

To analyse blood perfusion, dynamic contrast-enhanced MRIs for the bilateral proximal femora were performed 6 weeks after the injection of MPS using a 3.0 T superconducting system (ACS-NT Intera, Philips Healthcare, The Netherlands) described previously [16 (link), 22 (link)]. As the contrast agent, 0.8 mmol per kg of body weight of gadopentetatedimeglumine (Gd-DTPA, Magnevist, Schering, Berlin, Germany) was rapidly injected manually via a previously placed 21-gauge intravenous catheter in the right ear vein, followed by a 5-mL saline flush. A set of DCE-MRI was obtained soon after Gd-DTPA injection, and the signal intensity (SI) was measured. SI for each femur was plotted against time to create a time-signal intensity curve, and the perfusion index ‘maximum enhancement’ was calculated. Maximum enhancement was defined as (SI_max − SI_base)/SI_base × 100%. SI_base was the baseline signal intensity obtained before Gd-DTPA injection, and SI_max was the maximum signal intensity after Gd-DTPA injection.