Comparison of MRI and arthroscopy findings for transitional zone cartilage damage in the acetabulum of the hip joint.

OBJECTIVE: To assess the performance of morphologic and hypointense signal changes on MRI to predict grades and types of acetabular cartilage damage in the chondrolabral transitional zone (TZ) of the hip identified at arthroscopy. MATERIALS AND METHODS: This retrospective single-center study reviewed conventional 3T MRI hip studies from individuals with symptomatic femoroacetabular impingement (FAI) and subsequent hip arthroscopy surgery within 6 months. Independent review was made by three radiologists for the presence of morphologic damage or a hypointense signal lesion in the TZ on MRI. Fleiss' kappa statistic was used to assess inter-reader agreement. The degree of TZ surfacing damage (modified Outerbridge grades 1-4) and presence of non-surfacing wave sign at arthroscopic surgery were collected. Relationship between sensitivity and lesion grade was examined. RESULTS: One hundred thirty-six MRI hip studies from 40 males and 74 females were included (mean age 28.5 years, age range 13-54 years). MRI morphologic lesions had a sensitivity of 64.9-71.6% and specificity of 48.4-67.7% for arthroscopic surfacing lesions, with greater sensitivity seen for higher grade lesions. Low sensitivity was seen for wave sign lesions (34.5-51.7%). MRI hypointense signal lesions had a sensitivity of 26.3-62% and specificity of 43.8-78.0% for any lesion. Inter-reader agreement was moderate for morphologic lesions (k = 0.601) and poor for hypointense signal lesions (k = 0.097). CONCLUSION: Morphologic cartilage damage in the TZ on MRI had moderate sensitivity for any cartilage lesion, better sensitivity for higher grade lesions, and poor sensitivity for wave sign lesions. The diagnostic value of hypointense signal lesions was uncertain.

Ultrasound-guided nerve block prior to biopsy of suspected neurogenic tumors: safety and feasibility in a pilot study.

OBJECTIVE: The aim of this study is to investigate the safety and feasibility of ultrasound-guided nerve block prior to biopsy of potentially neurogenic tumors. MATERIALS AND METHODS: A retrospective review of the medical record from June 2017 to June 2022 identified ultrasound-guided biopsies of potentially neurogenic tumors that were performed with a pre-procedural nerve block. Patient demographics, biopsy site, number of passes, needle gauge, use of sedation, pathology results, and procedural complications were recorded and summarized. RESULTS: The structured search found 16 patients that underwent biopsies of 18 potentially neurogenic tumors with the use of a pre-procedural nerve block at a variety of upper and lower extremity locations. Average patient age was 52 (range 18-78) and 9 patients (56%) were female. Of the 16 patients, 10 were performed without intravenous sedation. Three patients were unable to tolerate biopsy until a nerve block was used. All biopsies yielded a diagnostic sample with 13 of the tumors neurogenic in origin. One patient reported mild postprocedural pain which resolved with conservative treatment; no other complications were reported. CONCLUSION: Nerve block prior to ultrasound-guided biopsy of potentially neurogenic tumors is a safe and feasible technique. Further study is needed to determine the extent to which nerve block can decrease intra-procedural pain and reduce or eliminate the need for sedation during biopsy.

Fluoroscopy-guided percutaneous needle aspiration of posterior epidural abscesses: a report of two cases.

Introduction: Spinal epidural abscesses are most commonly treated with surgical decompression and antibiotics or in specific instances managed medically with antibiotic therapy alone. Image-guided percutaneous aspiration as an alternative to surgery has only rarely been reported in the literature. Case presentation: We report two cases of successful fluoroscopy-guided needle aspiration of posterior epidural abscesses. Case 1 is a 48-year-old man who presented with several days of escalating back pain and constitutional symptoms with MRI showing a posterior epidural abscess at L2-L3 causing spinal stenosis. The patient remained neurologically intact. Percutaneous needle aspiration of the collection provided dramatic pain relief with the aspirate growing methicillin sensitive Staphylococcus aureus. The patient made a full recovery on antibiotic therapy. Case 2 is an 81-year-old man who presented with worsening upper back pain and was found to have osteomyelitis/discitis with a large posterior epidural abscess in the thoracic spine. Needle drainage was performed with the sample growing Bacteroides fragilis. This patient also responded successfully to nonsurgical management with full recovery after appropriate antibiotic therapy. Discussion: In carefully selected patients, image-guided needle aspiration of posterior epidural abscesses may be a viable and less invasive alternative to surgery.

Detection of pediatric musculoskeletal pathology using the fluid-sensitive sequence.

BACKGROUND: Musculoskeletal complaints are common among children, and magnetic resonance (MR) is increasingly used to supplement the clinical assessment. The validation of a short triage protocol could reduce the number of unnecessary contrast-enhanced MR studies that sometimes also require the need for sedation. OBJECTIVE: To compare the diagnostic accuracy between fluid-sensitive sequence and contrast-enhanced MR study in the detection of musculoskeletal pathology in the pelvis and the appendicular skeleton in children older than 2 years. MATERIALS AND METHODS: We performed a retrospective review between Feb. 1, 2016, and Oct. 31, 2016, and identified 99 studies from 96 patients (48 boys and 48 girls; mean age ± standard deviation, 11.1±4.6 years) without syndromic deformity, recent trauma, a history of infectious or inflammatory arthropathy, prior instrumentation or incomplete records. Two radiologists reviewed each study twice, at least 1 month apart, first using only the fluid-sensitive sequences (triage study) and later using the contrast-enhanced study. Readers rated the presence or absence of pathology independently and generated final impressions in consensus. We used Cohen's kappa (κ) and percentage agreement to compare agreement between readers and between studies, respectively. RESULTS: Inter-reader agreement was overall higher for the contrast-enhanced studies (κ range = 0.91-1) than for the triage studies (κ range = 0.49-1). Percentage agreement between studies was high for the detection of pathology (97-100%) and for the impressions (93%). Clinical diagnoses were stress reaction or overuse in 31%, infection in 21%, space-occupying process in 17%, normal in 15%, inflammatory in 14%, and both inflammatory and overuse in 1%. The full study increased diagnostic confidence in five studies and accuracy in two but did not alter management. CONCLUSION: The fluid-sensitive sequence had a near-perfect percentage of agreement with the contrast-enhanced study in the detection of musculoskeletal pathology and could possibly be used to screen children who need a contrast-enhanced MR study.

US Evaluation of Juvenile Idiopathic Arthritis and Osteoarticular Infection.

Juvenile idiopathic arthritis (JIA) and osteoarticular infection can cause nonspecific articular and periarticular complaints in children. Although contrast material-enhanced magnetic resonance imaging is the reference standard imaging modality, musculoskeletal ultrasonography (US) is emerging as an important adjunct imaging modality that can provide valuable information relatively quickly without use of radiation or the need for sedation. However, diagnostic accuracy requires a systemic approach, familiarity with various US techniques, and an understanding of maturation-related changes. Specifically, the use of dynamic, Doppler, and/or multifocal US assessments can help confirm sites of disease, monitor therapy response, and guide interventions. In patients with JIA, ongoing synovial inflammation can lead to articular and periarticular changes, including synovitis, tenosynovitis, cartilage damage, bone changes, and enthesopathy. Although these findings can manifest in adult patients with rheumatoid arthritis, important differences and pitfalls exist because of the unique changes associated with an immature and maturing skeleton. In patients who are clinically suspected of having osteoarticular infection, the inability of US to evaluate the bone marrow decreases its sensitivity. Therefore, the US findings should be interpreted with caution because juxtacortical inflammation is suggestive, but neither sensitive nor specific, for underlying osteomyelitis. Similarly, the absence of a joint effusion makes septic arthritis extremely unlikely but not impossible. US findings of JIA and osteoarticular infection often overlap. Although certain clinical scenarios, laboratory findings, and imaging appearances can favor one diagnosis over the other, fluid analysis may still be required for definitive diagnosis and optimal treatment. US is the preferred modality for fluid aspiration and administering intra-articular corticosteroid therapy. © RSNA, 2017.

Correlation Between Hip Arthroscopy Outcomes and Preoperative Anesthetic Hip Joint Injections, MR Arthrogram Imaging Findings, and Patient Demographic Characteristics.

OBJECTIVE: The purpose of this study is to determine whether the preoperative response to intraarticular hip anesthetic injection correlates with the outcome of hip arthroscopy. A secondary aim is to determine whether the outcome of arthroscopy correlates with intraarticular pathologic findings or patient demographic characteristics. MATERIALS AND METHODS: Ninety-three patients who underwent MR arthrography (MRA), preoperative injections of anesthetic into the hip joint (with pain scores documented), and subsequent hip arthroscopy (with a modified Harris Hip Score [mHHS] determined at 1 year after arthroscopy) were included in the study. MRA images and surgery reports were retrospectively reviewed to identify information about labral tear type and size and cartilage damage grade. The correlation between the response to hip anesthetic injection (defined as poor [0-30% improvement], moderate [31-60% improvement], or good [61-100% improvement]) and the surgical outcome (poor, fair, or good, as determined on the basis of the mHHS or the need for repeat surgery) was evaluated using the Fisher exact test. Univariate analysis (performed using the Fisher exact test) and multivariate analysis (performed using ANOVA) of correlations with age, sex, body mass index (BMI [weight in kilograms divided by the square of height in meters]), the interval between injection and surgery, labral tear type and size, and cartilage damage grade were also performed. RESULTS: Comparison of the response to preoperative hip anesthetic injection with the outcome of arthroscopy at 1 year indicated no statistically significant association (p = 0.59). The BMI of the patient, however, was statistically significantly associated with surgical outcome (p = 0.03), with a BMI of less than 25 denoting a higher likelihood of a good surgical outcome. No statistically significant correlations were noted in analyses of surgical outcomes and patient age (p = 0.31) and sex (p = 0.83); the interval between injection and surgery (p = 0.28); labral tear type, as determined by MRA (p = 0.34) and arthroscopy (p = 0.47); labral tear size, as determined by MRA (p = 0.34); and cartilage grade, as determined by MRA (p = 0.58) and arthroscopy (p = 0.26). CONCLUSION: No positive or negative correlation was noted between the response to preoperative hip anesthetic injection and the outcome at 1 year after hip arthroscopy. Only BMI was shown to correlate with the surgical outcome.

Magnetic resonance imaging of the meniscus.

The treatment of meniscal tears has evolved secondary to a better understanding of the essential roles that the menisci play in the normal function of the knee, including load transmission, stress distribution, shock absorption, joint lubrication, resistance to capsular and synovial impingement, and maintenance of joint congruity. Imaging evaluation of the menisci requires an understanding of the normal anatomy, the imaging criteria necessary to accurately diagnose a meniscal tear, meniscal tear patterns, and awareness of common diagnostic pitfalls.

MR imaging-based diagnosis and classification of meniscal tears.

Magnetic resonance (MR) imaging is currently the modality of choice for detecting meniscal injuries and planning subsequent treatment. A thorough understanding of the imaging protocols, normal meniscal anatomy, surrounding anatomic structures, and anatomic variants and pitfalls is critical to ensure diagnostic accuracy and prevent unnecessary surgery. High-spatial-resolution imaging of the meniscus can be performed using fast spin-echo and three-dimensional MR imaging sequences. Normal anatomic structures that can mimic a tear include the meniscal ligament, meniscofemoral ligaments, popliteomeniscal fascicles, and meniscomeniscal ligament. Anatomic variants and pitfalls that can mimic a tear include discoid meniscus, meniscal flounce, a meniscal ossicle, and chondrocalcinosis. When a meniscal tear is identified, accurate description and classification of the tear pattern can guide the referring clinician in patient education and surgical planning. For example, longitudinal tears are often amenable to repair, whereas horizontal and radial tears may require partial meniscectomy. Tear patterns include horizontal, longitudinal, radial, root, complex, displaced, and bucket-handle tears. Occasionally, meniscal tears can be difficult to detect at imaging; however, secondary indirect signs, such as a parameniscal cyst, meniscal extrusion, or linear subchondral bone marrow edema, should increase the radiologist's suspicion for an underlying tear. Awareness of common diagnostic errors can ensure accurate diagnosis of meniscal tears. Online supplemental material is available for this article.

MRI characteristics of healed and unhealed peripheral vertical meniscal tears.

OBJECTIVE: The objective of our study was to retrospectively compare the MRI characteristics of surgically confirmed healed and unhealed peripheral vertical meniscal tears. MATERIALS AND METHODS: The study group consisted of 64 patients with 86 peripheral vertical meniscal tears diagnosed on MRI who subsequently underwent knee surgery. The MRI examinations were retrospectively reviewed to assess the following tear characteristics: tear location relative to the meniscocapsular junction, tear width, tear length, tear extension through one or both surfaces, sequences on which tear was visualized, signal intensity of tear on T2-weighted imaging, and presence of low-signal-intensity strands bridging the tear on T2-weighted imaging. Multivariate logistic regression models were used to determine whether MRI characteristics could be used to distinguish between healed and unhealed tears at surgery. RESULTS: Tear location was the most significant characteristic (p<0.001) for distinguishing between healed and unhealed tears: 17 of 18 (94.4%) tears located at the meniscocapsular junction of the medial meniscus were healed and 15 of 68 (22.1%) tears not located at the meniscocapsular junction were healed. For tears not located at the meniscocapsular junction, MRI characteristics significantly associated with healed tears included a tear width of less than 2 mm (p=0.01), tear visualized only on intermediate-weighted imaging (p=0.01), tear showing intermediate or bright signal intensity on T2-weighted imaging (p=0.06), and low-signal-intensity strands bridging the tear on T2-weighted imaging (p<0.001). CONCLUSION: Most peripheral vertical tears at the meniscocapsular junction of the medial meniscus spontaneously heal. The MRI characteristics of tears not located at the meniscocapsular junction can help distinguish between healed and unhealed tears.

Magnetic resonance imaging and arthroscopic appearance of the menisci of the knee.

The menisci are critical for normal function of the knee, providing shock absorption and load transmission that reduce stress on the articular cartilage. When torn, a meniscus may require surgery to restore function, reduce pain, and eliminate mechanical symptoms. Patterns of meniscal tears include longitudinal and bucket-handle, which are often reparable; and horizontal, radial, vertical flap, horizontal flap, and complex. Root tears are usually radial and occur in the posterior roots. When reviewing magnetic resonance images, one must be aware of normal variants and imaging pitfalls that may simulate pathology.

Hounsfield units for assessing bone mineral density and strength: a tool for osteoporosis management.

BACKGROUND: Measurements obtained from clinical computed tomography examinations may yield information leading to the diagnosis of decreased bone mineral density, without added expense to the patient. The purpose of the present study was to determine if Hounsfield units, a standardized computed tomography attenuation coefficient, correlate with bone mineral density and compressive strength. METHODS: Twenty-five patients (including eighteen female and seven male patients with a mean age of 71.3 years) undergoing both lumbar spine dual x-ray absorptiometry scans and computed tomography imaging were evaluated to determine if Hounsfield units correlated with bone mineral density and T-scores. Normative data were generated from lumbar spine computed tomography examinations for eighty consecutive trauma patients and were stratified by age and sex. Separately, polyurethane foam blocks of varying densities were imaged with computed tomography and were subjected to mechanical testing to determine compressive strength. Compressive strength values and Hounsfield units were analyzed for correlation. RESULTS: Significant correlations were found between Hounsfield units and bone mineral density, age, and T-scores and between Hounsfield units and compressive strength (p < 0.001). CONCLUSIONS: Hounsfield units obtained from clinical computed tomography scans that are made for other purposes correlate with dual x-ray absorptiometry scores as well as compressive strengths based on osseous models and potentially provide an alternative method for determining regional bone mineral density at no additional cost to the patient. The information could conceivably be applied toward fracture risk assessment, diagnosis of osteoporosis, and early initiation of needed treatment.

The current state of imaging the articular cartilage of the upper extremity.

MR imaging has increasingly been used to image joints since its inception. Historically, there has been more emphasis on the evaluation of internal derangement rather than cartilaginous disease. This article reviews cartilaginous diseases of the upper extremity emphasizing those that can be assessed using current clinical MR imaging protocols and addresses the limitations of current imaging techniques in evaluating the articular cartilage of smaller joints. It also provides a brief overview of novel techniques that may be instituted in the future to improve the diagnostic performance of MR imaging in the evaluation of the articular cartilage of the upper extremity.

Musculoskeletal ultrasound: how to treat calcific tendinitis of the rotator cuff by ultrasound-guided single-needle lavage technique.

OBJECTIVE: The purpose of this video article is to illustrate the ultrasound appearance of calcium deposition in the rotator cuff and provide a detailed step-by-step protocol for performing the ultrasound-guided single-needle lavage technique for the treatment of calcific tendinitis with emphasis on patient positioning, necessary supplies, real-time lavage technique, and steroid injection into the subacromial subdeltoid bursa. CONCLUSION: Musculoskeletal ultrasound is well established as a safe, cost-effective imaging tool in diagnosing and treating common musculoskeletal disorders. Calcific tendinitis of the rotator cuff is a common disabling cause of shoulder pain. Although most cases are self-limiting, a subset of patients is refractory to conservative therapy and requires treatment intervention. Ultrasound-guided lavage is an effective and safe minimally-invasive treatment not readily offered in the United States as an alternative to surgery, perhaps because of the limited prevalence of musculoskeletal ultrasound programs and limited training. On completion of this video article, the participant should be able to develop an appropriate diagnostic and therapeutic algorithm for the treatment of calcific tendinitis of the rotator cuff using ultrasound.