Dynamic magnetic resonance sialography for patients with xerostomia

MR Sialography: A Pictorial Review

“…While the evolution of the MR sialographic technique has brought about improved image quality, intrinsic disadvantages of the MR imaging technique remain, including suboptimal spatial resolution (compared with conventional sialography); suboptimal signal intensity-to-noise ratio (SNR) of the T2-weighted hydrographic technique; lower contrast resolution of calcifications (relative to conventional or CT sialographic techniques); and specific MR imaging artifacts, including dental amalgam, motion, and susceptibility effects. [3][4][5] Several applications, including the evaluation of sialolithiasis, 3,5,6-9 ductal stenosis, 3,6,7,9 xerostomia, [10][11][12] Sjö gren syndrome, [13][14][15][16] juvenile recurrent parotitis, 17 and sialadenitis, 3,8,18 have been described in the literature.…”

“…To achieve strong T2-weighting of pulse sequences, numerous MR sialographic protocols have been described in the literature, most which are described at a 1.5T field strength. The technical specifics of these protocols are beyond the scope of this review, but prior studies have shown the utility of several techniques, including 3D constructive interference in the steady-state (CISS), 3,5,17 half-Fourier acquisition single-shot turbo spin-echo, 3,17 2D fast asymmet-ric spin-echo (FASE) dynamic postsialogogue, 12,19 T2weighted turbo spin-echo, 6 T2-weighted spin-echo sequence with 3D and maximum-intensity-projection reconstructions, 6 3D fast recovery fast spin-echo, 4 3D heavily T2-weighted TSE with and without a frequency and spatially selective binomial radio-frequency water-selective pulse sequence, 10 3D-FASE, 20,21 3D fast spin-echo, 15 T2-weighted single-shot TSE, 8 3D extended-phase conjugate-symmetry rapid spin-echo (3D-EXPRESS), 7 2D heavily T2-weighted FSE, 9,18 T2-weighted single-shot FSE, 13 and rapid acquisition with relaxation enhancement. 5,14 For each of these techniques, supplemental coils are used and the specific coil used varies by institution.…”

“…Several authors have advocated adjuvant techniques to improve the quality of MR sialographic studies, including salivary stimulation 4,5,12,22 and passive ductal occlusion. 4 These techniques aim to increase salivary volume, resulting in more complete filling of the salivary duct tree with high T2 signal-intensity contrast, which in turn results in improved SNR of the MR sialographic technique.…”

“…MR sialography has evolved from a strictly anatomic imaging technique; and with the implementation of dynamic, postsialogogue protocols, radiologists may now achieve quantifiable, functional salivary gland imaging. 12,19 Building on methods described by Morimoto et al, 21 Tanaka et al 12 imaged patients every 30 seconds postsialogogue (citric acid 5% drops) administration by using a 2D-FASE sequence with a single-section acquisition of thick sections. Significant differences in maximal cross-sectional ductal diameter, total salivary volume, and response to the sialogogue were demonstrated between healthy controls and patients with xerostomia.…”

“…24,25 Furthermore, unlike traditional 99m Tcpertechnetate salivary gland scintigraphy, dynamic MR sialography does not use ionizing radiation or radiopharmaceuticals, obviating appropriate radioisotope storage, administration, and disposal. 12 Advances in scanner and coil technology now allow fluidsensitive, high-spatial-resolution, single-slab, isotropic, volumetric acquisitions during MR sialography. These advances allow dynamic postprocessing and rendering of virtual sialoendoscopic views (Fig 3).…”