Dynamic manoeuvres on MRI in oral cancers – A pictorial essay

Abstract

Magnetic resonance imaging has been shown to be a useful tool in the evaluation of oral malignancies because of direct visualization of lesions due to high soft tissue contrast and multiplanar capability. However, small oral cavity tumours pose an imaging challenge due to apposed mucosal surfaces of oral cavity, metallic denture artefacts and submucosal fibrosis. The purpose of this pictorial essay is to show the benefits of pre and post contrast MRI sequences using various dynamic manoeuvres that serve as key sequences in the evaluation of various small oral (buccal mucosa and tongue as well as hard/soft palate) lesions for studying their extent as well as their true anatomic relationship.

Techniques, Tricks, and Stratagems of Oral Cavity Computed Tomography and Magnetic Resonance Imaging

“…However, MRI can overcome some limitations of MSCT in cases of small oral cavity lesions in patients with submucosal fibrosis, retromolar trigone lesion, and post-surgical complications. Metal dental artifacts are more obvious on MSCT images too [47]. These dynamic manoeuvres can be summarised as follows:…”

“…facial muscles (risorius, levatorangulioris, depressor angulioris, and orbicularis oris) create a broad soft tissue density pseudomass (arrowheads in (A)) that should not be confused with a real lesion. For best results, patients should move their tongue away from the hard palate and teeth to allow the tongue to be distinguished from the floor of the mouth/gingiva and the gingiva from the tongue/lip [47]. Henrot et al [28] proposed a modified puffed cheek technique for MRI.…”

“…It allows the separation of the palatal mucosa from the muscular component of the tongue clarifying the exact origin, infiltration, and thickness of tumoural masses (Figures 12 and 13). For best results, patients should move their tongue away from the hard palate and teeth to allow the tongue to be distinguished from the floor of the mouth/gingiva and the gingiva from the tongue/lip [47]. Henrot et al [28] proposed a modified puffed cheek technique for MRI.…”

“…Lingual protrusion causes "stretching" of the oropharyngeal structures and distends the glosso-tonsillar sulcus. Small lesions located on the lateral or ventral margin of the anterior tongue or located on the lingual apex are clearly highlighted by such manoeuvre [47].…”

“…This technique is exclusively used on MRI examinations since MRI has a high contrast for liquids by using specific sequences, especially T2 sequences. Water distension of the oral vestibule is performed by asking patients to drink 20-40 mL of still water and keep it in the mouth for the time necessary to acquire the images (T2 and pre-and post-contrast T1 sequences) [47]. This manoeuvre distends the oral vestibule and the presence of water provides excellent natural contrast between the lesion and the adjacent mucosal surfaces (Figure 17).…”