Acs nt intera

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.

For Dynamic MRI–derived vascular function index, rabbits were anesthetized with 2.5% sodium pentobarbital (0.4 ml/kg) and then placed in the prone position with lower limbs flexed for MRI scanning using a 1.5-T superconducting system (ACS-NT Intera; Philips Medical Systems, Best, The Netherlands) with a maximum gradient strength of 30 mT/m. A bolus of dimeglumine gadopentetate (Magnevist; Schering, Berlin, Germany) (0.3 mmol/kg/body weight) was rapidly injected by an automatic pump linked to a previously placed 21-gauge catheter into an auditory vein. Dynamic MRI scans were performed in the prescribed plane with the following parameters: short T1-weighted gradient echo sequence, TR/TE = 4/1.4 msec, flip angle = 15, slice thickness = 5 mm, in-plane resolution = 0.86 × 0.86 mm, average = 1. The temporal resolution was approximately 0.6 s per image acquisition. A series of dynamic images were obtained in 600 s to cover the wash-out phase3 (link)24 (link)37 (link)38 (link). The vascularization index ‘Peak Enhancement Percentage’ (PEP) and permeability index ‘Permeability Surface Area Product per Unit Volume of Tissue’ (PSρ) were accordingly calculated using our established protocol24 (link)25 (link).