MR arthrography of the labral capsular ligamentous complex in the shoulder: imaging variations and pitfalls

OBJECTIVE

Using MR arthrography, we examined normal anatomy, anatomic variations, and pitfalls of imaging the labral capsular ligamentous complex in the asymptomatic shoulder.

SUBJECTS AND METHODS

We obtained 108 MR arthrograms of the glenohumeral joint in 95 asymptomatic volunteers with axial (108 shoulders) and oblique coronal (56 shoulders) images. We examined labral shape, patterns of capsular insertion, presence or absence of glenohumeral ligaments, and pitfalls of imaging. Our patients were men (auxiliary policemen) between 19 and 24 years old (mean age, 21 years).

RESULTS

The shapes of labra were triangular (anterior part, 64%; posterior part, 47%), round (17%; 33%), flat (2%; 17%), cleaved (11%; 1%), notched (3%; 0%), or absent (2%; 2%). Using the system of Mosely and Overgaard, the anterior capsular insertion was type 1 in 63% of shoulders, type 2 in 20%, and type 3 in 17%; the posterior capsular insertion was type 1 in 60% of shoulders, type 2 in 31%, and type 3 in 9%. The superior and inferior glenohumeral ligaments were present in 99% of shoulders, but the middle glenohumeral ligament was present in only 79%. We also detected many pitfalls of MR imaging in identifying findings such as the undercutting of the labrum by cartilage (32% of shoulders), prominent axillary folds (46%), sublabral holes (7%) or recesses (33%), Buford complexes (2%), and sulci between the biceps tendon and superior labrum (30%).

CONCLUSION

Knowledge of normal anatomy and anatomic variations of the labral complex is important for the examination of the shoulder with MR arthrography.

Videostrobokymography: a new method for the quantitative analysis of vocal fold vibration

OBJECTIVES

To develop a new analysis method for the quantitative assessment of vibration of the vocal folds, using conventional videostroboscopic image data.

METHODS

We used prerecorded videostroboscopic images to evaluate quantitatively the vibration of the vocal folds. Successive images were converted as digital images by means of an image-grabbing board, processed for analysis, and reconstructed as kymograms by rearranging the same lines of all processed images along the time axis.

RESULTS

We developed a new technique for evaluating the vibration of the vocal folds. The vibrations of multiple vocal fold regions were easily and objectively evaluated by this technique. The objective parameters, such as open quotient and asymmetry index, could be obtained easily using this technique.

CONCLUSIONS

Videostrobokymography demonstrated objectively the vibrations of several vocal fold regions at the same time. This technique has the potential to be a new tool to analyze and monitor the pathological changes and treatment results of vocal fold movement in a more refined quantitative fashion, using videostroboscopic images.

Crosstalk reduction with a micromachined diaphragm structure for integrated ultrasound transducer arrays

Crosstalk reduction in a polyvinylidene fluoride (PVDF) integrated ultrasound transducer array with a micromachined diaphragm structure is reported. Three sets of linear arrays with nine 1 mmx1 mm elements on dielectric diaphragms have been made. They were fabricated with (1) a solid substrate, (2) a single large diaphragm window underneath the entire array, and (3) a small diaphragm window (SW) for each array element. To estimate crosstalk and fringe field effects in each array, the authors measured each array's angular response in the far field of an unfocused source transducer. A Fourier transform analysis was then performed on the measured data to obtain each array's directivity pattern, which in turn was fitted to theoretical curves based on a crosstalk model. Crosstalk-related parameters have been extracted from curve-fitting and their values show that the array with the SW structure for each element has the least electrical and acoustical crosstalk and fringe field effects.