Dynamic near‐real‐time magnetic resonance imaging for analyzing the velopharyngeal closure in comparison with videofluoroscopy

Abstract

Purpose:To demonstrate the feasibility of dynamic magnetic resonance imaging (MRI) with near-real-time temporal resolution ("real-time MRI") for analyzing the velopharyngeal closure in comparison with multiview videofluoroscopy. Materials and Methods:Seven patients (three females and four males, 5-21 years old, mean age ϭ 11.3 years) with suspected velopharyngeal insufficiency, and one healthy volunteer were examined with videofluoroscopy and real-time MRI using a turbo-spin-echo (TSE) sequence (TR ϭ 170 msec, TE ϭ 21 msec, slice thickness ϭ 6 mm, six images per second). Imaging was done during phonation in all three image planes. The results were analyzed by two radiologists in comparison with videofluoroscopy as the standard of reference for overall image quality and the pattern of velopharyngeal closure.Results: Real-time MRI correctly depicted the pattern of velopharyngeal closure in correspondence to videofluoroscopy in all cases. Concerning the movement of the pharyngeal walls, real-time MRI falsely depicted a general movement of the dorsal pharyngeal wall in one case, whereas videofluoroscopy showed no movement. In one patient, real-time MRI provided additional information by showing an asymmetric movement of the lateral pharyngeal walls that could not be depicted by videofluoroscopy due to technical limitations. Concerning image quality, the coronal plane was more difficult to evaluate with real-time MRI compared to videofluoroscopy. The axial plane was easier to analyze in real-time MRI compared to videofluoroscopy. Conclusion:Real-time MRI has the potential to depict the pattern of velopharyngeal closure in close correlation with videofluoroscopy, and may deliver additional information in selected cases.

Towards clinical assessment of velopharyngeal closure using MRI: evaluation of real-time MRI sequences at 1.5 and 3 T

“…As a result, MRI has been used to obtain images of the musculature of the palate at rest and during sustained phonation [10,18,19]. It has also been used to image the whole vocal tract at rest or during sustained phonation [20][21][22][23][24][25][26][27] and with a single mid-sagittal image dynamically during speech [13,[15][16][17][28][29][30][31][32][33][34][35].…”

“…Dynamic MRI of the vocal tract has been performed using both segmented [17,33,37] and real-time acquisitions [13,15,16,28,31,38]. Segmented acquisitions [39] acquire only a fraction of the k-space data required for each image during one repetition of the test phrase and, hence, require multiple identical repetitions.…”

“…The turbo spin echo (TSE) zoom technique [40] has been used to perform real-time MRI of the vocal tract [29,31] and is available as a clinical tool. The zoom technique excites a reduced field of view in the phase encode direction, hence allowing a smaller acquisition matrix and shorter scan for a constant spatial resolution.…”

“…The zoom technique excites a reduced field of view in the phase encode direction, hence allowing a smaller acquisition matrix and shorter scan for a constant spatial resolution. While such spin echo-based techniques are less susceptible to magnetic field inhomogeneity related signal dropout artefacts than other sequences, the frame rates achieved with these sequences are limited to 6 fps [31]. Gradient echo-based techniques have also been used to achieve similar temporal resolution [12,41,42] in the upper vocal tract, but are often used at much higher frame rates in other MRI applications such as cardiac imaging [43,44].…”

Dynamic 1.5-Tvs3-T true fast imaging with steady-state precession (trueFISP)-MRI sequences for assessment of velopharyngeal function

“…3 The structural resolution is acceptable; the repeatability and relative comfort for the patient are additional advantages. The information gained is similar to that of videofluoroscopy.…”