Visualization of swallowing using real-time TrueFISP MR fluoroscopy

Abstract

The aim of this study was to evaluate the ability of different real-time true fast imaging with steady precession (TrueFISP) sequences regarding their ability to depict the swallowing process and delineate oropharyngeal pathologies in patients with dysphagia. Real-time TrueFISP visualization of swallowing was performed in 8 volunteers and 6 patients with dysphagia using a 1.5 T scanner (Magnetom Sonata, Siemens, Erlangen Germany) equipped with high-performance gradients (amplitude 40 mT/m). Image quality of four different real-time TrueFISP sequences (TR 2.2–3.0 ms, TE 1.1–1.5 ms, matrix 63×128–135×256, field of view 250 mm², acquisition time per image 139–405 ms) was evaluated. Water, yoghurt, and semolina pudding were assessed as oral contrast agents. Functional exploration of the oropharyngeal apparatus was best possible using the fastest real-time TrueFISP sequence (TR 2.2 ms, TE 1.1 ms, matrix 63×128). Increased acquisition time resulted in blurring of anatomical structures. As the image contrast of TrueFISP sequences depends on T2/T1 properties, all tested foodstuff were well suited as oral contrast agents, but image quality was best using semolina pudding. Real-time visualization of swallowing is possible using real-time TrueFISP sequences in conjunction with oral contrast agents. For the functional exploration of swallowing high temporal resolution is more crucial than spatial resolution.