|Paper title||Feasibility of GRASP in clinical routine detection of pituitary microadenomas|
|Form of presentation||Poster|
To demonstrate the clinical feasibility of a novel MRI pulse sequence, Golden-angle radial sparce parallel MRI (GRASP) through comparison to the current imaging technique, dynamic contast enhanced (DCE) imaging in terms of image quality and lesion depiction in the detection of microlesions (microadenomas and cysts) of the pituitary gland.
16 patients (11 microadenomas, 5 cysts) underwent two MRI examinations (Siemens 1.5T and 3T) on separate dates, one using standard DCE (resolution 0.9 x 0.9 mm, slice thickness 2 mm, temporal resolution of 30 seconds) and the other using GRASP (spatial resolution 1.0 x 1.0 x 1.0 mm isotropic voxels, temporal resolution of 4 seconds). Two neuroradiologists separately recorded measures of image quality (Scale 1-5, 5=best), lesion size and contrast arrival times in terms of first and optimal lesion conspicuity.
In qualitiative analysis there were no significant differences in terms of average visual image sharpness (DCE 3.9 0.9, GRASP 3.9 0.9, p> 0.05) or visual contrast scores (DCE 4.1 1.2, GRASP 4.4 0.8, p > 0.05). Pearson's correlation coefficients for interreader lesion measurements (width and height, mm) ranged from substantial to almost perfect agreement (r= 0.73 to 0.88). Analysis of contrast arrival times revealed an average lesion first-conspicuity time of 60.7 16.7 s for DCE compared to 50.2 10.3 s for GRASP with a difference of 10.5 16.2 s (p=0.023). Lesion best-conspicuity was 91.9 39.5 s for DCE compared to 77.4 23.6 s for GRASP (p> 0.05).
The significant difference in average contrast arrival times for lesion first-conspicuity between DCE and GRASP shows the advantage of the continuous data acquisition with GRASP. Even though the in-plane resolution for the isotropic GRASP voxels was less than the anisotropic DCE voxels no significant difference in visual assessment was found on GRASP images. For microadenoma detection GRASP is feasible in clinical routine, delivers visually similar results and detects microadenoma at least as reliable as DCE. Taking into account the known robustness against motion artefacts and the advantage of earlier detection of microadenomas with GRASP this technique might offer better diagnostic yield than DCE which is to be proved in larger cohorts.