Normal magnetic resonance imaging anatomy of the tongue, oropharynx, hypopharynx, and larynx

A preliminary application of principal components and cluster analysis to internal tongue deformation patterns

Complex patterns of muscle contractions create gross tongue motion during speech. It is of scientific and medical importance to better understand speech motor strategies and variations due to language or disorders. Dense patterns of tongue motion can be imaged using tagged magnetic resonance imaging, but characterisation of motion strategies is difficult using visualisation alone. This paper explores the use of principal component analysis for dimensionality reduction and cluster analysis for tongue motion categorisation. Velocity fields were acquired and analysed from midsagittal tongue slices during motion from /i/ to /u/ for eight datasets containing multiple languages and a glossectomy patient. The analyses were carried out on the tongue-only and tongue-plus-floor of the mouth regions. The results showed that both the analyses were sensitive to region size and that cluster analysis was harder to interpret. Both the analyses grouped the Japanese speaker with the glossectomy patient, which although explicable with biologically plausible reasons, highlights the limitations of extensive data reduction.

Measuring tongue motion from tagged cine-MRI using harmonic phase (HARP) processing

A cine series of tagged magnetic resonance (MR) images of the tongue is used to measure tongue motion and its internal deformation during speech. Tagged images are collected in three slice orientations (sagittal, coronal, and axial) during repetitions of the utterance "disouk" (/disuk/). A new technique called harmonic phase MRI (HARP-MRI) is used to process the tagged MR images to measure the internal deformation of the tongue. The measurements include displacement and velocity of tissue points, principal strains, and strain in the line-of-action of specific muscles. These measurements are not restricted to tag intersections, but can be calculated at every pixel in the image. The different motion measurements complement each other in understanding the tongue kinematics and in hypothesizing the internal muscle activity of the tongue.

Ultrasonic assessment of the anatomy and function of the tongue

The tongue is a complex muscular structure. Apart from its intrinsic strength, it has a major influence on the adjacent bony structures. Real time ultrasound appears to be the method of choice for assessing the topographic and functional anatomy. The examination was performed using an Acuson 128 scanner, with a 5 MHz probe, either a sector scanner (sagittal plane) or linear array probe (coronal plane). The scans were performed using the sub-hyoid approach, between the rami of the mandible. The images were stored on U-matic videotape. Thirty adult patients were included in the study population. The scan protocol consisted of an examination of the tongue at rest, a scan of the swallowing mechanism with and without a liquid bolus and a study of the posterior lingual positions (which show some anatomical variation). The intrinsic muscles of the tongue and the floor of the mouth could be identified on the "at rest" images. The lingual mass is the most important parameter and is opposed against the palate in order to propel a bolus during the swallowing mechanism. The mobility, shape and supporting structures of the tongue are variable depending on the nature of the bolus, the patient and the two imaging planes. Ultrasound is a simple and non-invasive method for the examination of the buccal cavity. The function of the posterior portion of the tongue must be taken into consideration prior to any treatment concerning the oral cavity.

Magnetic resonance imaging of head and neck tumors

Magnetic resonance imaging has revolutionized the imaging of head and neck malignancies and is now rapidly replacing computed tomography as the study of choice in the majority of lesions in the head, neck, larynx, hypopharynx, oropharynx, paranasal sinuses, paranasopharynx, and skull base. CT scanning can be used in the same region; however, inflammation obtained in CT is not as clearly demonstrated and in some situations, such as malignancies of the tongue, the lesions may be missed entirely. There are still occasional difficult clinical problems when the two studies are complementary, but this situation will definitely be rare.