Improved renal perfusion measurement with a dual navigator-gated Q2TIPS fair technique.

A dual navigator-gated, flow-sensitive alternating inversion recovery (FAIR) true fast imaging with steady precession (True-FISP) sequence has been developed for accurate quantification of renal perfusion. FAIR methods typically overestimate renal perfusion when respiratory motion causes the inversion slice to move away from the imaging slice, which then incorporates unlabeled spins from static tissue. To overcome this issue, the dual navigator scheme was introduced to track inversion and imaging slices, and thus to ensure the same position for both slices. Accuracy was further improved by a well-defined bolus length, which was achieved by a modification version of Q2TIPS (quantitative imaging of perfusion using a single subtraction, second version with interleaved thin-slice TI(1) periodic saturation): a series of saturation pulses was applied to both sides of the imaging slice at a certain time after the inversion. The dual navigator-gated technique was tested in eight volunteers. The measured renal cortex perfusion rates were between 191 and 378 mL/100 g/min in the renal cortex with a mean of 376 mL/100 g/min. The proposed technique may prove most beneficial for noncontrast-based renal perfusion quantification in young children and patients who may have difficulty holding their breath for prolonged periods or are sedated/anesthetized.