Theodore T. Miller

Fat-suppressed MRI of musculoskeletal infection: fast T2-weighted techniques versus gadolinium-enhanced T1-weighted images

Abstract Purpose. To investigate gadolinium’s role in imaging musculoskeletal infection by comparing the conspicuity and extent of inflammatory changes demonstrated on gadolinium-enhanced fat-suppressed T1-weighted images versus fat-suppressed fast T2-weighted sequences. Design. Eighteen patients with infection were imaged in a 1.5-T unit, using frequency-selective and/or inversion recovery fat-suppressed fast T2-weighted images (T2WI) and gadolinium-enhanced frequency-selective fat-suppressed T1-weighted images (T1WI). Thirty-four imaging planes with both a fat-suppressed gadolinium-enhanced T1-weighted sequence and a fat-suppressed T2-weighted sequence were obtained. Comparison of the extent and conspicuity of signal intensity changes was made for both bone and soft tissue in each plane. Results. In bone, inflammatory change was equal in extent and conspicuity on fat-suppressed T2WI and fat-suppressed T1WI with gadolinium in 19 planes, more extensive or conspicuous on T2WI in three planes, and less so on T2WI in two planes. Marrow was normal on all three sequences in 10 cases. In soft tissue, inflammatory change was seen equally well in 20 instances, more extensively or conspicuously on the T2WI in 11 instances, and less so on T2WI in 2 instances. One case had no soft tissue involvement on any of the sequences. Five abscesses and three joint effusions were present, all more conspicuously delineated from surrounding inflammatory change on the fat-saturated T1WI with gadolinium. The average imaging time for the fat-saturated T1WI with gadolinium was 6.75 min, while that of the T2-weighted sequences was 5.75 min. Conclusion. Routine use of gadolinium is not warranted. Instead, gadolinium should be reserved for clinically suspected infection in or around a joint, and in cases refractory to medical or surgical treatment due to possible abscess formation.

Sonography of injury of the ulnar collateral ligament of the elbow—initial experience

ObjectiveThe purpose of this study is to describe the sonographic appearance of injuries of the ulnar collateral ligament (UCL) of the elbow.Design and patientsEight non-professional male baseball pitchers, ages 13–35 years, with medial elbow pain and clinical suspicion of ulnar collateral ligament injury, were referred for imaging. All eight underwent sonography of the affected and contralateral asymptomatic elbow, and six also underwent MR imaging. Neither valgus stress nor power Doppler was used during the sonographic examinations. Time from onset of symptoms to imaging was 1.5 weeks to 6 months. Three patients had surgical confirmation of their injuries, with time from imaging to surgery of 2 days to 9 months.ResultsIn four patients, the UCL was ruptured, manifest sonographically in three cases as discontinuity of the normally hyperechoic ligament with anechoic fluid in the gap and in one case as non-visualization of the ligament with heterogeneous echogenicity in the expected location of the ligament. Two adolescent patients had avulsions of the UCL from the medial epicondyle, with sonographic demonstration of the avulsed echogenic bony fragment in both cases. One patient had a mild sprain, manifest as mild thickening and decreased echogenicity of the ligament sonographically compared with the contralateral normal elbow, with mild surrounding hypoechoic edema. The eighth patient had a small partial tear of the deep surface of the distal aspect of the ligament, visualized as a hypoechoic focus between the deep surface of the ligament and its ulnar attachment.ConclusionTears of the ulnar collateral ligament are manifested sonographically as non-visualization of the ligament or alteration of the normal morphology.

MRI Findings in Painful Metal-on- Metal Hip Arthroplasty

OBJECTIVE The objective of our study was to compare the frequency of osseous and soft-tissue abnormalities in patients presenting with hip pain after resurfacing arthroplasty and after total hip arthroplasty (THA), correlate the MRI findings with histologic results, and determine which MRI findings are predictive of aseptic lymphocytic vasculitis-associated lesions. MATERIALS AND METHODS The MRI examinations of patients with metal-on-metal hip prostheses placed at resurfacing arthroplasty (n=31) or THA (n=29) were reviewed for osteolysis, synovitis, extracapsular disease, synovial pattern, and mode of decompression into adjacent bursae. Regional muscles and tendons were assessed for tendinosis, tear, atrophy, and edema. Histologic and operative findings were reviewed in 19 patients (20 hips) who underwent revision surgery. Chi-square tests were performed to detect differences between the resurfacing arthroplasty and THA groups. The Wilcoxon rank sum test was performed to detect differences in MRI findings in patients with and those without aseptic lymphocytic vasculitis-associated lesions. RESULTS Synovitis was detected in 77.4% of resurfacing arthroplasty hips and 86.2% of THA hips. Extracapsular disease was present in 6.5% of resurfacing arthroplasty hips and 10.3% of THA hips. Osteolysis was detected in 9.7% of resurfacing arthroplasty hips and 24.1% of THA hips. There was no difference in the incidence of synovitis (p=0.51), osteolysis (p=0.17), or extracapsular disease (p=0.67) between the resurfacing arthroplasty and THA groups. Patients with aseptic lymphocytic vasculitis-associated lesions had higher volumes of synovitis (p=0.04) than patients without aseptic lymphocytic vasculitis-associated lesions. Extracapsular disease and muscle edema were seen only in patients with aseptic lymphocytic vasculitis-associated lesions. CONCLUSION Synovitis is common in patients with metal-on-metal hip prostheses and occurs with a similar incidence after resurfacing arthroplasty and after THA; osteolysis and extracapsular disease are uncommon. The MRI signs most suggestive of aseptic lymphocytic vasculitis-associated lesions are high volumes of synovitis, extracapsular disease, and intramuscular edema.

Lamellated Hyperintense Synovitis: Potential MR Imaging Sign of an Infected Knee Arthroplasty

PURPOSE To determine the sensitivity and specificity of lamellated hyperintense synovitis for infection following knee arthroplasty and to determine the inter- and intraobserver variability of this sign at magnetic resonance (MR) imaging. MATERIALS AND METHODS The purpose of the retrospective case control study was approved by the hospitals institutional review board. MR images from 28 patients with proved infected total knee arthroplasty and 28 patients with noninfected arthroplasty were reviewed by two musculoskeletal radiologists for the presence of lamellated hyperintense synovitis. Cases were rereviewed 2 weeks later by each reader. The sensitivity and specificity were calculated with the initial reads. The κ statistic was used to assess inter- and intraobserver reliability. RESULTS The sensitivity of lamellated hyperintense synovitis for infection was 0.86-0.92 (95% confidence interval [CI]: 0.75, 0.97) and the specificity was 0.85-0.87 (95% CI: 0.74, 0.94). There was almost perfect interobserver agreement (κ = 0.82; 95% CI: 0.72, 0.93; P < .001) and intraobserver agreement (for reader 1, κ = 0.89 [95% CI: 0.78, 1.00; P < .001] and for reader 2, κ = 0.89 [95% CI: 0.77, 1.00; P < .001]) in the classification of the synovial pattern. CONCLUSION In this selected series of patients, the presence of lamellated hyperintense synovitis at MR imaging of knee arthroplasty had a high sensitivity and specificity for infection. This sign had high inter- and intraobserver reliability.

Spectral Doppler Sonography of Musculoskeletal Soft Tissue Masses

Objective. To determine whether resistive indices obtained from spectral Doppler waveforms can be used to distinguish benign from malignant musculoskeletal soft tissue masses. Methods. A retrospective review of Doppler sonograms was performed for 52 patients with 53 soft tissue masses. All masses showed internal flow on color or power Doppler sonography, and spectral Doppler sonography yielded waveforms from which resistive indices were calculated. This information was analyzed along with the histologic diagnosis of each lesion with significance set at P > .05. Results. There were 19 benign lesions and 34 malignancies. The resistive indices of the benign masses ranged from 0.44 to 1.0 (mean ± SD, 0.72 ± 0.42), whereas the malignant masses had resistive indices ranging from 0.28 to 1.0 (mean, 0.62 ± 0.36). There was no statistically significant (P > .05) difference between the resistive indices of benign and malignant lesions. Conclusions. Resistive indices cannot be used to distinguish benign from malignant musculoskeletal soft tissue masses.

MR arthrography of the shoulder and hip after fluoroscopic landmarking.

Abstract  Purpose. To describe a technique for intra-articular injection in the MR suite after conventional fluoroscopic landmarking in order to streamline MR arthrography. Design and patients. This technique was performed on 33 consecutive patients referred for MR arthrography of the shoulder to evaluate the glenoid labrum and on 15 consecutive patients referred for MR arthrography of the hip to evaluate the acetabular labrum. The patients were landmarked in the fluoroscopy suite, followed by a conventional MR examination. The intra-articular injection was then performed on the MR table and the MR arthrographic sequences obtained. Results. One of the 48 injections was extra-articular, requiring a second injection. The other injections were performed without incident, and the average total procedure time for all injections was 10 min. Conclusions. This technique is a reliable method of streamlining intra-articular injections when performing conventional MR imaging prior to the MR arthrographic portion of the examination. It shortens the total MR examination time by eliminating a visit to the fluoroscopy suite in the middle of the MR study, and its use of a straight anterior approach for both the shoulder and hip joints should be familiar to most people who perform conventional arthrography.

Sonographic Evaluation of Femoral Trochlear Cartilage in Patients With Knee Pain

The purpose of this study was to investigate whether routine clinical sonographic evaluation of femoral trochlear cartilage can identify abnormalities in patients with knee pain.

Isolated injury of the cuboid bone

Abstract. The purpose of this study was to describe isolated injury of the cuboid bone as a potentially radiographically occult cause of foot pain. The imaging studies of 17 patients, 13 women and 4 men aged 17–79 years (average 45 years), who presented with pain over the lateral aspect of the midfoot were retrospectively reviewed. Frontal, lateral, and inversion-oblique radiographs were available for all patients. In addition, MR imaging was performed in eight patients, CT in two, conventional tomography in two, and bone scan in one. Conventional radiographs revealed cuboid fracture in seven patients. Of the remaining ten, eight underwent MR imaging which demonstrated four fractures, three bone bruises, and one stress reaction, and two had tomography, CT, and/or bone scan, all of which documented an isolated cuboid fracture. Isolated fracture of the cuboid may be radiographically occult. Other imaging modalities, particularly MR imaging, can document this injury as the source of pain.

Sonography of Supraspinatus Tendon Abnormalities in the Neutral Versus Crass and Modified Crass Positions A Prospective Study

The purpose of this study was to investigate how well the neutral arm position correlates with the Crass and modified Crass positions in sonographic evaluation of supraspinatus tendon abnormalities.

Comparative Analysis of 2- Versus 3-Dimensional Sonography of the Supraspinatus Tendon

The purpose of this study was to determine the reliability in the analysis of images acquired using a dedicated 3‐dimensional (3D) ultrasound transducer and conventional 2‐dimensional (2D) images in the detection and characterization of supraspinatus tendon tears.