Gadolinium-enhanced multiphasic 3D MRI of the liver with prospective adaptive navigator correction: phantom study and preliminary clinical evaluation.

OBJECTIVE: The purpose of this study was to determine whether prospective adaptive navigator correction improves slice position invariability while maintaining image quality and enables efficient cine display observation on gadolinium-enhanced multiphasic thin-slice 3D MRI of the liver. MATERIALS AND METHODS: The study consisted of two parts: a phantom study and a clinical study. To explore the effect of navigator correction, a phantom was imaged in the resting state and in continuous movement. In the clinical study, gadolinium-enhanced four-phase 3D spoiled turbo field-echo images (3-mm thickness with no intersectional gap, 60 slices for whole liver) were retrospectively assessed. The subjects were 83 patients with 130 focal hepatic lesions randomized into two groups: with (n = 45) and without (n = 38) navigator correction. Images were qualitatively assessed by two blinded radiologists using a three-point slice position invariability scale for liver and focal hepatic lesions. Image degradation due to motion or artifacts was qualitatively assessed. RESULTS: Phantom images were obtained with excellent slice position invariability while image quality was maintained with navigator correction. Navigator correction substantially degraded the quality of the images of two patients (one with a large amount of ascites and the other with a large hepatic cyst). In the other 81 patients, the degree of slice position invariability for the liver was greater (p < 0.001) with (score, 2.84 +/- 0.43 [SD]) than without (score, 2.37 +/- 0.75) navigator correction. For focal hepatic lesions, slice position invariability also was greater (p < 0.0001) with (score, 2.95 +/- 0.21) than without (score, 2.18 +/- 0.88) navigator correction. No difference in degree of image degradation was found with or without navigator correction. CONCLUSION: Prospective navigator correction improves slice position invariability for cine display observation while preserving image quality for gadolinium-enhanced multiphasic thin-slice 3D MRI of the liver.