Randomly segmented central k-space ordering in high-spatial-resolution contrast-enhanced MR angiography of the supraaortic arteries: initial experience.

Contrast material-enhanced three-dimensional (3D) magnetic resonance (MR) angiography of the supraaortic arteries with randomly segmented central k-space ordering (ie, contrast-enhanced timing-robust angiography [CENTRA]) was performed in 16 patients. CENTRA enabled reliable depiction of the aortic arch up to the circle of Willis at high spatial resolution (true voxel size, 0.81 x 0.81 x 1.0 mm(3)). With CENTRA, the divergent demands of high spatial resolution, wide anatomic coverage, and arterial phase imaging have been reconciled. The random order of central k-space acquisition may minimize artifacts in contrast-enhanced 3D MR angiography caused by unstable contrast material opacification at the initiation of sampling.

Evaluation of a new ultrasmall superparamagnetic iron oxide contrast agent Clariscan, (NC100150) for MRI of renal perfusion: experimental study in an animal model.

PURPOSE: To determine the diagnostic value of a new ultrasmall superparamagnetic iron oxide Clariscan, (NC100150) for the evaluation of renal perfusion in an animal model using a 3D-FFE-EPI sequence. MATERIALS AND METHODS: Four groups of four rabbits each were imaged after bolus injection of NC100150, using a 1.5 T MR system (Gyroscan ACS-NT). T2*w MR images in the coronal plane were acquired over 60 seconds with an echo-shifted 3D-FFE-EPI sequence (TR/TE/alpha = 18/25 msec/8 degrees ). Data were transferred to a workstation and converted into concentration curves. Based on the fitted concentration time curves, parameter maps were calculated pixelwise: bolus arrival time (T0), time-to-peak (TTP), mean transit time (MTT), and relative bolus volume (rBV). Maximum signal decrease was determined with respect to the baseline value. RESULTS: Mean MTT increased from 4.2 seconds at a dose of 0.25 mg to 5.9 seconds at 1.0 mg (P < .0001). The maximum signal decrease was observed at 0.75 mg, corresponding to 85% of the baseline value. Transit times of the contrast bolus were accurately calculated for the cortex and the outer medulla, but at the level of the inner medulla no arterial flow profile was identified. No significant difference between the cortex and the outer medulla was found for either T0 or rBV, but medullar TTP and MTT were prolonged with regard to cortical TTP and MTT (6.3 seconds vs. 5.7 seconds, P < .001; 5.7 seconds vs. 4.2 seconds, P < .0001). CONCLUSION: The employed intravascular contrast agent is well suited to assess renal perfusion. By the use of a T2*w3D perfusion sequence, cortical and medullar transit times can be quantified and physiologic information on regional perfusion differences can be obtained.