Jamie L. Perry

High-Resolution Dynamic Speech Imaging with Joint Low-Rank and Sparsity Constraints

To enable dynamic speech imaging with high spatiotemporal resolution and full‐vocal‐tract spatial coverage, leveraging recent advances in sparse sampling.

Variations in Velopharyngeal Structures Between Upright and Supine Positions Using Upright Magnetic Resonance Imaging

Objective No studies have used MRI to compare the dimensional changes of the velopharyngeal musculature between upright and supine positions. The purpose of this study is to provide a comparison between structures of the velopharyngeal mechanism while in the supine and upright positions during rest and sustained speech productions of four female subjects. Methods Four healthy white female subjects between 30 and 36 years of age (mean, 32.5 ± 1.75 years) were imaged using a 0.6-tesla open-type multi-position MRI scanner. Subjects produced two speech tasks (/i/ and /s/) in the two body positions. Results Velar measures (length, thickness, and height), pharyngeal measures (retrovelar and retrolingual), and levator muscle measures (length and angles of origin) demonstrated a small variation between upright and supine positions. Differences in velar height during production of /i/ between the two positions was significant for all subjects. In most cases, the velar thickness remained nearly the same (group mean difference was between –0.2 and 1.2 mm). Group means demonstrated an average levator muscle shortening from upright to supine of 2.8 mm at rest, 2.0 mm during /i/ production, and 2.3 mm during /s/ production. Percentage of levator shortening were 17% for /i/ production and 21% for /s/ production, which were independent of body position. Conclusions Overall, gravity had a minimal effect on velar thickness, velar length, velar height, levator muscle length, angles of origin, and pharyngeal dimensions. Differences between the two body positions (upright and supine) were not significant during rest or during production of /i/ and /s/, with the exception of velar height during /i/ production.

Morphology of the Levator Veli Palatini Muscle Using Magnetic Resonance Imaging

Background No studies have reported the circumference and diameter of the levator veli palatini muscle at multiple points along its length and from both views (frontal and lateral). The purpose of this study was to provide quantitative data regarding the levator muscle morphology along the length of the muscle using magnetic resonance imaging and advanced three-dimensional computer technology. Methods Ten Caucasian male subjects participated in the study. Subjects were scanned using a Siemens 3 T Trio. Levator muscle measures were obtained using a two-dimensional image plane. A three-dimensional model was used to measure the circumference and muscle diameter (in two directions) at six points along the length of the levator muscle. Results Levator muscle length ranged from 41.67 mm to 52.85 mm across all subjects. Mean extravelar muscle length was 30.55 mm (SD, 2.8 mm) and 30.01 mm (SD, 2.9 mm) for right and left muscles. The mean circumference at the origin was 18.90 mm (SD, 2.6 mm). At the second point, the muscle circumference mean increased slightly (mean, 22.40 mm; SD, 4.9 mm). The means for the remainder of the measures (points 3, 4, 5, and 6) were consistent, showing little to no change. Conclusion Circumference and diameter values were similar to those reported in previous literature. The muscle did diverge at the point where the muscle bundle entered the velum, as it has been previously described. Instead, the muscle diverges near the midline insertion becoming sparser (smaller superior-to-inferior diameter).

Anatomy and physiology of the velopharyngeal mechanism.

Understanding the normal anatomy and physiology of the velopharyngeal mechanism is the first step in providing appropriate diagnosis and treatment for children born with cleft lip and palate. The velopharyngeal mechanism consists of a muscular valve that extends from the posterior surface of the hard palate (roof of mouth) to the posterior pharyngeal wall and includes the velum (soft palate), lateral pharyngeal walls (sides of the throat), and the posterior pharyngeal wall (back wall of the throat). The function of the velopharyngeal mechanism is to create a tight seal between the velum and pharyngeal walls to separate the oral and nasal cavities for various purposes, including speech. Velopharyngeal closure is accomplished through the contraction of several velopharyngeal muscles including the levator veli palatini, musculus uvulae, superior pharyngeal constrictor, palatopharyngeus, palatoglossus, and salpingopharyngeus. The tensor veli palatini is thought to be responsible for eustachian tube function.

Using MRI for assessing velopharyngeal structures and function.

Objective Direct visualization of the velopharynx and, in particular, the levator muscle is particularly important in the assessment of velopharyngeal function and normal speech production. The purpose of this study is to demonstrate the development of a static and dynamic magnetic resonance imaging protocol for evaluation of velopharyngeal structures and function. Methods A high-resolution, T2-weighted turbo-spin-echo three-dimensional anatomical scan (sampling perfection with application optimized contrasts using different flip angle evolution) was used to acquire a large field of view covering the velopharyngeal anatomy. Dynamic speech assessment was obtained using a fast-gradient echo, fast low-angle shot, multi-shot spiral technique to acquire 15.8 frames per second (FPS) of the sagittal and oblique coronal image planes. Results Using a three-dimensional data set, as opposed to two-dimensional data, the full contour of the levator muscle can be appreciated. Dynamic images were obtained at 15.8 FPS in the sagittal and oblique coronal planes, enabling visualization of the movements of the velum, posterior pharyngeal wall, lateral pharyngeal walls, and levator muscle during speech. Conclusions A three-dimensional magnetic resonance imaging sequence, such as that used in the present study, may provide better analyses and more precise measurements. A dynamic fast low-angle shot sequence allows for visualization of the levator muscle and the velum during speech at a high image rate. This protocol could have a significant impact in improving the process of visualizing pathology and promoting clinical treatment plans for individuals born with cleft lip and palate.

Magnetic resonance imaging and computer reconstruction of the velopharyngeal mechanism.

Further research is needed to fully understand the mechanics of the levator veli palatini muscle in coordination with surrounding structures in individuals born with a cleft palate. The purpose of this study was to combine magnetic resonance imaging (MRI) and three-dimensional computer modeling and animation to study the velopharyngeal mechanism in infants with and without a cleft palate. Two infants with a normal velopharyngeal anatomy (subjects 1 and 2) and 2 infants with a cleft lip and palate (subjects 3 and 4) were scheduled to receive a whole-head MRI for clinical reasons unrelated to the current study. This study demonstrated a successful method for combining MRI and three-dimensional computer technology to study the velopharyngeal mechanism in infants with and infants without a cleft palate. Subject 1 displayed a levator muscle sling arrangement that was shaped like a narrow U, whereas subject 2 had a wider U-shaped muscle arrangement. Subject 4 exhibited smaller angles of origin in the oblique coronal compared with that of subject 1. Both subjects with a normal anatomy showed steeper muscles compared with those of both subjects with a cleft palate. The current study enhances the body of literature in the area of MRI by acquiring MR images from infants before and after primary palatoplasty and combining the imaging with three-dimensional computer technology. The angles of the levator muscle may prove to be a significant factor in velar elevation for normal speech.

Craniometric and velopharyngeal assessment of infants with and without cleft palate.

Background: The current study was designed to obtain qualitative and quantitative information of the velopharyngeal mechanism and craniometric dimensions in infants born with a normal mechanism and in infants with an unrepaired cleft palate. Materials and Methods: Clinical magnetic resonance imaging data were obtained from the medical charts of 4 infants (2 with cleft lip and palate and 2 without) between the ages of 8 and 9 months. Craniometric measures and levator veli palatini muscle morphology were analyzed using visualization modeling software. Both raw measures and measures normalized by head circumference were examined. Results: Patients 1 and 2 demonstrated normal velopharyngeal anatomy and a similar distance between levator muscle origins (38.9-40.7 mm), sagittal angles of origin (56-57 degrees), and levator muscle bundle lengths (28.4-30.7 mm). Patients with an unrepaired cleft palate displayed smaller oblique coronal angles of origins (58-62 degrees) compared with patients without cleft palate (62-67 degrees). Patients without cleft palate showed a steeper muscle (56-57 degrees) compared with patients without cleft palate (66-67 degrees). The basion-sella-nasion angle, hard palate length, and hard palate width measurements are related systematically to head circumference in this patient group. Discussion: Results from the current study are in agreement with previous studies demonstrating variations across patients with cleft palate particularly in the muscle bundle lengths, distance between muscle origins, velar thickness, and velar length. Longitudinal studies are needed to determine how levator muscle and craniometric dimensions vary between those with and without cleft palate. A larger sample size is necessary to provide statistical analysis.

Anthropometric Analysis of the Velopharynx and Related Craniometric Dimensions in Three Adult Populations Using MRI

Objective The purpose of this study is to examine effects of sex, race, and craniometry among three distinct racial groups of adults with normal velopharyngeal anatomy and to determine whether craniofacial structures could be used to predict velopharyngeal structures. Methods A total of 88 adults across three racial groups including white, black, and Asian (Japanese) participated. Magnetic resonance images were obtained using a high-resolution, three-dimensional anatomical scan. Measurements were obtained on the levator veli palatini muscle, velum, and craniofacial structures. Results Head circumference was used as a covariate to control the effect of overall cranial size on the analyses. Palate height, linear cranial base, and face height and width vary based on sex, with men demonstrating larger values compared with women. Linear base values, cranial base angle, and face width vary significantly based on race, with Japanese subjects showing the smallest anterior to posterior measures and larger face-width values. Levator muscle measures, excluding angle measures, vary significantly (P < .0001) based on sex. There was no statistically significant difference (P > .05) among racial groups in the levator muscle measures. Velar length and thickness varied significantly based on race and sex. Conclusions This is the first study to examine the interaction of race and sex on levator muscle morphology. In spite of the differences in velar dimensions, no significant differences were found in muscle size, specifically the levator veli palatini, which is contained within the velum.

Sexual dimorphism of the levator veli palatini muscle: an imaging study.

Objective Magnetic resonance imaging studies of the levator veli palatini muscle have used small numbers of subjects and have not consistently controlled for sex, race, or age. The purpose of this study was to conduct a structural assessment using a large homogeneous sample to examine the sex differences in the levator muscle morphology. Methods Thirty white adult subjects (15 men and 15 women) were imaged using a 3 Tesla MRI system. A high-resolution SPACE (sampling perfection with application-optimized contrasts using different flip-angle evolution) sequence was used to acquire images of the velopharyngeal anatomy. Levator muscle measurements were obtained. Results Men displayed significantly greater levator extravelar segment length (P = .003), levator intravelar segment muscle length (P < .001), greater distance between levator insertion points (P < .001), and greater angles of origin (P = .008) compared with women. There was no statistically significant variation between men and women in the distance between points of origin at the base of the skull. Conclusions This study provides normative data to improve understanding of levator dysmorphology such as that in cleft palate muscle anatomy. Results of the study demonstrate significant differences between white men and women across several levator muscle measures. Variations in the relative size of the cranium or height of the individual were not proportionate to the variations observed in the levator muscle.

Effects of gravity on the velopharyngeal structures in children using upright magnetic resonance imaging.

Objective The influence of gravity on the velopharyngeal structures in children is unknown. The purpose of this study is to compare the velopharyngeal mechanism in the upright and supine positions while at rest and during sustained speech production in children between 4 and 8 years old. Methods A 0.6 Tesla open-type, multipositional magnetic resonance imaging scanner was used to image subjects in the upright and supine positions. The scanning protocol included a T2 fluid attenuation inversion recovery and an oblique coronal turbo spin echo scan with short scanning durations (7.9 seconds) to enable visualization of the velopharyngeal anatomy during rest and production of sustained /i/ and /s/. Results The magnetic resonance imaging protocol used for this study enabled successful visualization of the velopharyngeal anatomy in the sagittal and oblique coronal planes at rest and during sustained phonation of /i/ and /s/. Positional differences demonstrated a small nonsignificant (P > .05) variation for velar measures (length, thickness, and height), retrovelar space, and levator veli palatini measures (length and angles of origin). Conclusions Gravity had a negligible effect on velar length, velar thickness, velar height, retrovelar space, levator muscle length, and levator angles of origin. Supine imaging data can be translated to an upright activity such as speech. This is the first study to provide normative levator muscle lengths for children between 4 and 8 years old. Upright imaging may be a promising tool for difficult-to-test populations.