Faculty Bibliography

The aim of this study was to evaluate the ability of power Doppler sonography to distinguish between hypoechoic fluid and synovium in patients with suspected tenosynovitis. Gray scale sonography and power Doppler sonography were performed on 26 tendons in 24 patients with tenosynovitis and 30 tendons in five asymptomatic volunteers. Peritendinous blood flow was graded on a scale of 0 to 3 and the percentage of the hypoechoic rim that contained blood flow was also noted. In the symptomatic group, flow was demonstrated in more than 50% of the peritendinous hypoechoic rim in 17 of 26 tendons. A positive correlation was found between the power Doppler sonographic grade and the percentage of the rim that had flow. These results suggest that a significant proportion of the hypoechoic rim probably represents vascularized synovium rather than complex fluid.

PURPOSE: To normalize the power Doppler ultrasound (US) signal to the expected signal from 100% blood in the calculation of a fractional moving blood volume estimate. MATERIALS AND METHODS: To locate the signal from flowing blood with a consistent backscatter coefficient, the authors estimated the knee of the cumulative Doppler power distribution function. They used a flow-tube phantom to test the use of this knee to locate a radial position that would fall into a region of high shear stress and minimal rouleaux formation. They also studied how well the method normalized fractional moving blood volume estimates of the right renal cortex in a volunteer when simulating different body habitus and in a group of six healthy volunteers to estimate variability. RESULTS: Over five flow velocities and over undersaturated to severely oversaturated receiver gains, the calculated flow-tube area was a mean 89% +/- 7 (+/- standard deviation) of a standard. In humans, the technique normalized the fractional moving blood volume estimates over an 8-dB receiver gain variation; the mean +/- standard deviation of fractional moving blood volume estimates for the six volunteers was 37.6% +/- 3.6. CONCLUSION: Vascularity estimates with power Doppler US are feasible with a normalization scheme based on the cumulative Doppler power distribution function.

OBJECTIVE: The purpose of this study was to show the ability of power Doppler sonography (PDS) to evaluate exercise-induced changes in muscle blood volume. SUBJECTS AND METHODS: We evaluated 20 biceps muscles with PDS in 10 healthy volunteers before and after they underwent a standardized exercise protocol. Intramuscular blood volume was qualitatively analyzed using a subjective scoring system to evaluate vascular conspicuity, comparing sonograms obtained before and after exercise. We also collected preliminary data on the quantification of estimated fractional moving blood volume (EFMBV) measured on sonograms obtained in eight biceps muscles of five volunteers. Assessment of significance was calculated using a Wilcoxon signed-rank correlation of significance. The stability of relative changes in EFMBV was also assessed with measurements performed at three different times in five healthy volunteers. RESULTS: With exercise, all 20 biceps muscles showed a significant subjective increase in apparent vascularity (p < .0005). Likewise, preliminary data on EFMBV showed significant increases (p < .01) between baseline and peak exercise values (mean, 470%; range, 180-900%). CONCLUSION: PDS revealed marked increases in intramuscular vascular conspicuity after exercise. EFMBV provided a potentially useful parameter to document such increases quantitatively.

We measured the incidence of cuff retear and injury to the suprascapular nerve after mobilization and repair of a massive rotator cuff tear. Of one hundred four rotator cuff repairs performed over a 5-year period, 10 patients (7 men and 3 women, age range 22 to 68 years) had primary repairs of massive rotator cuff tears requiring cuff mobilization and an acromioplasty as their only procedure. These patients were evaluated at a mean of 2.5 years (range 2.0 to 3.0 years) after surgery. At follow-up electromyographic examination confirmed that 1 of the 10 patients had an iatrogenic suprascapular nerve injury, whereas ultrasound evaluation revealed that 2 of 10 repairs failed. Pain relief was achieved in the eight patients with intact repairs and not in the two with recurrent tears. All patients had some limitation of active motion or strength, especially in external rotation. Thus 7 of 10 patients had neither evidence of nerve injury nor recurrent rotator cuff tears yet still showed limited active motion or weakness. It appears that operative injury to the suprascapular nerve during cuff mobilization can occur, but other factors such as inadequate cuff muscle function are more frequently responsible for the poor functional outcomes seen after successful repairs of massive rotator cuff tears.

We describe a patient with unexplained hypercalcemia who under went bone scintigraphy, which demonstrated marked tracer uptake within the hilar lymph nodes. The pattern strongly suggested sarcoidosis, which was subsequently confirmed by bronchoscopy-directed biopsy.

The majority of adults over the age of 65 y develop osteoarthritis (OA), a joint disease characterized by degeneration of articular cartilage and subchondral sclerosis. Early in the disease, the articular cartilage surface begins to change histologically from a smooth to a rough or fibrillated appearance. A prerequisite for any chondroprotective pharmacological intervention is detection of OA in its preclinical phase. Current diagnostic imaging modalities, such as radiographs or (nuclear) magnetic resonance imaging, either cannot directly image the cartilage surface or lack sufficient resolution to detect surface fibrillations. We have developed an ultrasonic technique that can be used to characterize these surface fibrillations directly. We present our in vitro results with validation by laser-based confocal microscopic imaging.

Power Doppler sonography was used in eight symptomatic knees in seven patients with arthritis before and after joint aspiration and intraarticular administration of steroids. A qualitative decrease in synovial perfusion was observed in all eight knees, and symptoms improved in seven of the eight cases. These preliminary data suggest a role for power Doppler sonography in assessment of serial changes in synovial inflammation.

A projection-operator technique is applied to a general three-component model for magnetization transfer, extending our previous two-component model [R.S. Adler and H.N. Yeung, J. Magn. Reson. A 104, 321 (1993), and H.N. Yeung, R. S. Adler, and S.D. Swanson, J. Magn. Reson. A 106, 37 (1994)]. The PO technique provides an elegant means of deriving a simple, effective rate equation in which there is natural separation of relaxation and source terms and allows incorporation of Redfield-Provotorov theory without any additional assumptions or restrictive conditions. The PO technique is extended to incorporate more general, multicomponent models. The three-component model is used to fit experimental data from samples of human hyaline cartilage and fibrocartilage. The fits of the three-component model are compared to the fits of the two-component model.

The integrated power Doppler signal arising from blood flow is a random process. In this article, a general approach to model this random process is studied. Both the theoretical and experimental results show that the temporal autocorrelation function of the integrated power Doppler signals is directly related to properties of the insonified medium, such as the scattering strengths and velocities of all moving scatterers, and as well as the properties of the Doppler imaging system, such as the point spread function (psf) of the power Doppler images. Some initial experiments are performed to test the proposed model. Its potential application for flow measurement, such as perfusion evaluation, is also discussed.

Evaluation of a painful total knee replacement has been limited to physical examination, aspiration, plain radiographs, and radionuclide studies. Visualization of the polyethylene tibial-bearing component without surgery has not been possible. Polyethylene wear is a well-recognized cause of total knee replacement failure. We have developed an ultrasound method to evaluate polyethylene insert shape and thickness with the ability to clearly demonstrate structural loss of plastic. Before clinical trials, a total knee replacement was cemented into a fresh cadaver knee. Ultrasound imaging of the polyethylene insert was performed in the longitudinal plane using a 10 MHz linear transducer. A characteristic bone/metal/polyethylene interface enabled recognition of the insert material from which its dimension was estimated. The entire perimeter of the liner, the metal tray, and the bone-metal interface was visualized. Five consecutive measurements at each location were performed on each of the 8-, 10-, and 12-mm polyethylene liners with the ultrasonographer blind to the insert thickness. Once removed, measurements were made directly on the liners adjacent to the marked points with an electronic caliper. Coefficient of variation (r2) ranged from 1.6% to 8.3% for the ultrasound measurements, and 0.26% to 1.5% for the caliper measurements. A plot of ultrasound versus caliper measurements allowed calculation of a linear equation, with r2 = 0.98, demonstrating high correlation between the two measurements. Our ultrasound measurements are accurate to 0.5 mm with a 95% confidence interval. Ultrasound is an accurate way to measure the dimensions of the polyethylene liner in total knee replacement arthroplasty. Early experiences with ultrasound evaluation prior to revision have been very encouraging for the evaluation of polyethylene wear, defects, and of prosthetic loosening.