RESUMEN
This study was performed to assess the feasibility of investigating the complex lingual myoarchitecture through segmentation of muscles from diffusion tensor imaging (DTI) data. The primary eigenvectors were found to be adequate for delineating the superior and inferior longitudinalis, genioglossus, and hyoglossus. The tertiary eigenvector orientations effectively revealed the homogeneous and systematic change of muscle orientation in the tongue core. In the longitudinalis near the tongue tip, the secondary eigenvectors were oriented in the radial direction. Lingual muscles were segmented using two methods: modified directional correlation (DC) and tensor coherence (TC) methods. The DC method, based on one eigenvector, was found to be inadequate for lingual muscle segmentation, whereas the TC method, based on the tensor shape and orientation, was used successfully to segment most lingual muscles. The segmentation result was used to report the diffusion tensor properties of individual lingual muscles. Also found was a continuous change in skewness of the intrinsic tongue core from negative in the anterior region to positive in the posterior region. DTI and the proposed segmentation method provide an adequate means of imaging and visualizing the complex, compartmentalized musculature of the tongue. The potential for in vivo research and clinical applications is demonstrated.
Asunto(s)
Imagen de Difusión por Resonancia Magnética/métodos , Imagenología Tridimensional/métodos , Fibras Musculares Esqueléticas , Procesamiento de Señales Asistido por Computador , Lengua/anatomía & histología , Animales , Anisotropía , Bovinos , Aumento de la Imagen , Músculo Esquelético/anatomía & histologíaRESUMEN
The time dependence of the apparent diffusion tensor of ex vivo calf heart and tongue was measured for diffusion times (tau(d)) between 32 and 810 ms. The results showed evidence of restricted diffusion in the muscle tissues of both organs. In regions where the myofibers are parallel, the largest eigenvalue (lambda(1)) of the diffusion tensor remained the same for all diffusion times measured, while the other eigenvalues (lambda(2), lambda(3)) decreased by 29-36% between tau(d) = 32 ms and tau(d) = 400 ms. In regions where the fibers cross, the lambda(1) also changed, decreasing by 17% between tau(d) = 32 ms and tau(d) = 400 ms. The restricting compartment size and volume fraction were effectively estimated by fitting the time courses of the eigenvalues to a model consisting of a nonrestricted compartment and a cylindrically restricted compartment. To our knowledge, this study is the first demonstrating diffusion time dependence of measured water diffusion tensor in muscular tissue. With improvement in scanning technology, future studies may permit noninvasive, in vivo detection of changes in muscle myoarchitecture due to disease, treatment, and exercise.
Asunto(s)
Imagen de Difusión por Resonancia Magnética/métodos , Interpretación de Imagen Asistida por Computador/métodos , Músculo Esquelético/citología , Músculo Esquelético/metabolismo , Miocardio/citología , Miocardio/metabolismo , Agua , Algoritmos , Animales , Anisotropía , Bovinos , Simulación por Computador , Difusión , Aumento de la Imagen/métodos , Técnicas In Vitro , Tasa de Depuración Metabólica , Modelos Biológicos , Lengua/citología , Lengua/metabolismo , Agua/metabolismoRESUMEN
Because of its distinct advantage in radiation-free soft tissue imaging, ultrasonography has been widely used to study lingual, pharyngeal, hyoid, laryngeal, and even esophageal action during swallowing in individuals of all ages. Qualitative ultrasonographic observations have made considerable contributions to our understanding of deglutition. Quantitative ultrasonographic swallowing research has also grown by leaps and bounds over the years with advances in imaging technologies and analytical methodologies. As a technical primer for new investigators, this paper reviews the modem methods for quantitative analysis in ultrasonographic swallowing research. The intended outcome is a basic understanding of the application of ultrasonography with various analysis options to the quantitative study of the deglutitive action of selected upper aerodigestive structures. Though proven useful for swallowing research, ultrasonography has inherent limitations and methodological issues. Future technological advancement and sophisticated image processing and analysis algorithms will resolve some of these issues.
Asunto(s)
Deglución/fisiología , Laringe/diagnóstico por imagen , Faringe/diagnóstico por imagen , Lengua/diagnóstico por imagen , Fenómenos Biomecánicos , Humanos , Laringe/fisiología , Movimiento , Faringe/fisiología , Lengua/fisiología , Transductores , Ultrasonografía/instrumentación , Ultrasonografía/métodosRESUMEN
OBJECTIVE: To determine whether real-time ultrasound imaging can provide quantitative data that distinguish pathologic from healthy muscle and that correlate with strength measures. DESIGN: Nonrandomized matched-pair, repeated-measures design. SETTING: Ultrasound imaging laboratory, rehabilitation medicine department, government research hospital. PARTICIPANTS: Nine patients with stable active or inactive myositis, stratified into 3 groups based on their 10-point manual muscle test (MMT) scores, and 9 age- and gender-matched controls. INTERVENTIONS: Maximal isometric contraction of the rectus femoris muscle in 2 knee-flexion positions (60 degrees, 90 degrees ) during simultaneous ultrasound imaging and muscle force dynamometry. MAIN OUTCOME MEASURES: Changes of the rectus femoris muscle in horizontal (X) and vertical (Y) diameters between relaxed and contracted states, and muscle force measurements. RESULTS: The X diameters decreased and the Y diameters increased during isometric contraction in all participants. For each group, average changes in cross-sectional diameters were consistently higher in controls than in patients. Patients with MMT less than 8 differed significantly from controls in both X and Y dimensions. A moderately strong correlation was found between muscle force and the Y diameter during contraction at 60 degrees (r =.78) and 90 degrees (r =.67) knee-flexion angles. CONCLUSIONS: Ultrasonography provided a quantitative measure of change between relaxed and contracted state of muscle, which correlated with muscle force. Ultrasound identified significant differences in cross-sectional diameters between the myopathic and normal muscles sampled and may be useful for measuring muscle response to drug and exercise therapy.
Asunto(s)
Debilidad Muscular/diagnóstico por imagen , Miositis/diagnóstico por imagen , Adulto , Estudios de Casos y Controles , Femenino , Humanos , Contracción Isométrica/fisiología , Masculino , Persona de Mediana Edad , Debilidad Muscular/fisiopatología , Músculo Esquelético/patología , Análisis de Regresión , Muslo , UltrasonografíaRESUMEN
Using ultrasonography with head and transducer stabilization, this study examined the effects of maximally controlled, systematic changes in bolus viscosity (thin juice-like, 7 cP; nectar-like, 243-260 cP; honey-like, 724-759 cP; spoon-thick, 2760-2819 cP) and volume (5, 10, 20, 30 cc) on hyoid kinematics in 31 healthy subjects (16 male, 15 female) in three age groups (20-39, 40-59, 60-79 years). Frame-by-frame hyoid displacements were tracked from digitized images of 612 swallows. Measures of movement durations, maximal amplitudes, total distances, and peak velocities were subjected to repeated measures multivariate analyses of variance with viscosity, volume, age, and gender as factors. Results showed that (1) spoon-thick swallows had the greatest preswallow gesture and total movement durations; (2) larger-volume swallows had significantly greater maximal amplitudes, forward peak velocity, and total vertical distance; (3) older subjects had longer start-to-max duration (though shorter preswallow gesture and total movement durations), greater maximal vertical amplitude, longer total vertical distance, and greater backward peak velocity than younger subjects; (4) males had greater values for all kinematic parameters except preswallow gesture, hyoid-at-max, and max-to-end durations. The results illustrate the importance of examining the interrelations among kinematic variables to better understand task accommodation and motor control strategies. The evidence also supports the concept of suprahyoid-infrahyoid functional adaptation and compensation in the healthy elderly.
Asunto(s)
Fenómenos Biomecánicos , Deglución/fisiología , Hueso Hioides/fisiología , Movimiento/fisiología , Viscosidad , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valores de ReferenciaRESUMEN
Past videofluoroscopic and EMG evidence has shown that rapid sequential swallowing differs from discrete swallows, but our knowledge of the control strategies remains incomplete. This study examined in detail the interrelationships among kinematic variables to discern the strategies for deglutitive hyoid motion during discrete (5 cc, 10 cc, 20 cc, 30 cc) and rapid sequential (120 cc) swallowing tasks. Submental ultrasound was conducted with head and transducer stabilization on 30 healthy subjects (15 males, 15 females) in three age groups (20-39, 40-59, 60-79 yrs). Frame-by-frame changes in hyoid position were tracked from digitized images of 236 discrete and 318 rapid sequential swallows. Repeated-measures analyses of variance were conducted on a number of kinematic variables with corrections for multiple tests and comparisons. The main effect of task was significant for all variables except forward peak velocity. Per post hoc contrasts, rapid sequential swallows had significantly reduced maximal amplitude (maximal displacement), total distance, backward peak velocity, at-max and total durations, and time to backward peak velocity in comparison with discrete swallows of any volume. Amplitude "down-scaling" was the prominent kinematic strategy used to accomplish rapid sequential swallows in a shorter time while keeping forward peak velocity essentially unchanged. In contrast, amplitude "up-scaling" was the strategy for accommodating larger-volume discrete swallows. Our results confirm built-in flexibility in the functional range of deglutitive hyoid motion.