To Explore the Changes and Differences of Microstructure of Vocal Fold in Vocal Fold Paralysis and Cricoarytenoid Joint Dislocation by Diffusion Tensor Imaging

OBJECTIVE

The diffusion characteristics of water molecules were measured in the vocal folds of canines exhibiting unilateral vocal fold paralysis and unilateral cricoarytenoid joint dislocation. These characteristics were used in conjunction with a histological examination of the microstructural changes of vocal fold muscle fibers to explore the feasibility of diffusion tensor imaging (DTI) in distinguishing unilateral vocal fold paralysis and unilateral cricoarytenoid joint dislocation as well as evaluating microstructural changes.

METHODS

Ten beagles were randomly divided into three groups: four in the unilateral vocal fold paralysis group, four in the unilateral cricoarytenoid joint dislocation group, and two in the normal group. Unilateral recurrent laryngeal nerve resection was performed in the vocal fold paralysis group. Unilateral cricoarytenoid joint dislocation surgery was performed in the dislocation group. No intervention was performed in the normal group. Four months postintervention, the larynges were excised and put into a magnetic resonance imaging (MRI) system (9.4T BioSpec MRI, Bruker, German) for scanning, followed by an analysis of diffusion parameters among the different groups for statistical significance. After MRI scanning, the vocal folds were cut into sections, stained with hematoxylin and eosin, and scanned digitally. The mean cross-sectional area of muscle fibers, and the mean diameter of muscle fibers in the vocal folds were calculated by target detection and extraction technology. Mean values of each measurement were used to compare the differences among the three groups. Pearson correlation analysis was performed on the DTI parameters and the results from histological section extraction.

RESULTS

The paralysis group had significantly higher Fractional Anisotropy (FA) compared to the dislocation group and normal group (P = 0.004). The paralysis group also had a significantly lower Tensor Trace value compared to the dislocation group and normal group (P = 0.000). The average cross-sectional area of vocal fold muscle fibers in the paralysis group was significantly smaller than the dislocation group and normal group (P = 0.000). Pearson correlation analysis yielded values of, r = -0.785, P = 0.01 between the average cross-sectional area of vocal muscle fibers and FA, and values of r = 0.881, P = 0.00 between Tensor Trace and the average cross-sectional area of vocal muscle.

CONCLUSION

FA and Tensor Trace can be used as effective parameters to reflect the changes of microstructure in vocal fold paralysis and cricoarytenoid joint dislocation. DTI is an objective and quantitative method to effectively evaluate unilateral vocal fold paralysis and unilateral cricoarytenoid joint dislocation, also capable of noninvasively evaluating vocal fold muscle fiber microstructure.

Diffusion tensor imaging and diffusion modeling: Application to monitoring changes in the medial gastrocnemius in disuse atrophy induced by unilateral limb suspension

BACKGROUND

Diffusion tensor imaging (DTI) assesses underlying tissue microstructure, and has been applied to studying skeletal muscle. Unloading of the lower leg causes decreases in muscle force, mass, and muscle protein synthesis as well as changes in muscle architecture.

PURPOSE

To monitor the change in DTI indices in the medial gastrocnemius (MG) after 4-week unilateral limb suspension (ULLS) and to explore the feasibility of extracting tissue microstructural parameters based on a two-compartment diffusion model.

STUDY TYPE

Prospective cohort study.

SUBJECTS

Seven moderately active subjects (29.1 ± 5.7 years).

FIELD STRENGTH/SEQUENCE

3T, single-shot fat-suppressed echo planar spin echo sequence.

ASSESSMENT

Suspension-related changes in the DTI indices (eigenvalues: λ₁ , λ₂ , λ₃ , fractional anisotropy; coefficient of planarity) were statistically analyzed. Changes in model-derived tissue parameters (muscle fiber circularity and diameter, intracellular volume fraction, and residence time) after suspension are qualitatively discussed.

STATISTICAL TESTS

Changes in the DTI indices of the MG between pre- and postsuspension were assessed using repeated-measures two-way analysis of variance (ANOVA).

RESULTS

All the eigenvalues (λ₁ : P = 0.025, λ₂ : P = 0.035, λ₃ : P = 0.049) as well as anisotropic diffusion coefficient (P = 0.029) were significantly smaller post-ULLS. Diffusion modeling revealed that fibers were more circular (circularity index increased from 0.55 to 0.95) with a smaller diameter (diameter decreased from 82-60 μm) postsuspension.

DATA CONCLUSION

We have shown that DTI indices change with disuse and modeling can relate these voxel level changes to changes in the tissue microarchitecture.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018.

Significance of Diffusion Tensor Imaging of Vastus Medialis Oblique in Recurrent Patellar Dislocation

Background:

Numerous studies have investigated the influence of osseous factors on patellofemoral joint instability, but research on the influence of dynamic muscle factors in vivo is still in the exploratory stage. This study aimed to use magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) to evaluate vastus medialis oblique (VMO) fiber bundles in patients with recurrent patellar dislocation to explore the changes in muscle morphology and function.

Methods:

This prospective study involved 30 patients (7 males and 23 females; average age, 21.4 ± 3.8 years) clinically diagnosed with recurrent patellar dislocation in Peking University Third Hospital and 30 healthy volunteers matched for age, sex, and body mass index in our medical school between January 2014 and October 2014. None of the patients had a recent history of traumatic patellar dislocation or transient patellar dislocation. All patients underwent conventional MRI and DTI of the knee. The cross-sectional area of the VMO on MRI and the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and primary (λ1), secondary (λ2), and three-level characteristic (λ3) values on DTI were measured. The independent-samples t-test was used to compare these parameters between the two groups.

Results:

Compared with the control group, the patient group showed significantly higher FA values (0.39 ± 0.05 vs. 0.33 ± 0.03) and significantly lower ADC (1.51 ± 0.13 vs. 1.58 ± 0.07), λ2 (4.96 ± 0.13 vs. 5.04 ± 0.07), and λ3 values (4.44 ± 0.14 vs. 4.58 ± 0.07; t = 5.99, t = –2.58, t = –3.02, and t = –4.88, respectively; all P < 0.05). Cross-sectional VMO area and λ1 values did not differ between the two groups (t = –1.82 and t = 0.22, respectively; both P > 0.05).

Conclusions:

The functional status of the VMO is closely associated with recurrent patellar dislocation. MRI, especially DTI (FA, ADC, λ2, and λ3), can detect early changes in VMO function and might facilitate the noninvasive monitoring of the functional status of the VMO in patients with recurrent patellar dislocation.

Techniques and applications of skeletal muscle diffusion tensor imaging: A review

Diffusion tensor imaging (DTI) is increasingly applied to study skeletal muscle physiology, anatomy, and pathology. The reason for this growing interest is that DTI offers unique, noninvasive, and potentially diagnostically relevant imaging readouts of skeletal muscle structure that are difficult or impossible to obtain otherwise. DTI has been shown to be feasible within most skeletal muscles. DTI parameters are highly sensitive to patient-specific properties such as age, body mass index (BMI), and gender, but also to more transient factors such as exercise, rest, pressure, temperature, and relative joint position. However, when designing a DTI study one should not only be aware of sensitivity to the above-mentioned factors but also the fact that the DTI parameters are dependent on several acquisition parameters such as echo time, b-value, and diffusion mixing time. The purpose of this review is to provide an overview of DTI studies covering the technical, demographic, and clinical aspects of DTI in skeletal muscles. First we will focus on the critical aspects of the acquisition protocol. Second, we will cover the reported normal variance in skeletal muscle diffusion parameters, and finally we provide an overview of clinical studies and reported parameter changes due to several (patho-)physiological conditions.