Faculty Bibliography

OBJECTIVE:To retrospectively evaluate the diagnostic utility of dual-energy computed tomography (DECT) virtual non-calcium bone marrow edema (BME) maps in the assessment of osseous pelvic trauma compared to conventional CT. In addition to fracture detection rates, we sought to determine the DECT effect on reader diagnostic confidence and follow-up recommendations. MATERIALS AND METHODS/METHODS:Three radiologists performed independent retrospective reviews of 92 consecutive pelvic CTs for the presence of fractures, without the use of DECT-generated BME maps. Following a washout period of ≥ 4 weeks, the cases were re-reviewed with the addition of DECT BME maps. Comparison of fracture detection rates, frequency of "indeterminate" reads, reader confidence ratings, and follow-up imaging recommendations were performed using McNemar's test and mixed-effects logistic regressions. Mixed-effect models were utilized to assess the effect of DEXA-derived patient bone mineral density, when available, on fracture detection rates. RESULTS:The use of DECT BME maps resulted in higher pooled reader diagnostic confidence, with a mean 0.19 increase on a 5-point Likert scale (p < 0.001). There was, however, no statistically significant difference in fracture detection rates for readers utilizing DECT versus conventional CT alone, with similar rates of "indeterminate" interpretations between the groups. For patients with recent DEXAs (n = 27), DECT was not associated with change in fracture detection rates among patients with osteoporosis or osteopenia. Readers recommended follow-up imaging more frequently in cases interpreted with DECT, but this effect was not significant (p = 0.266). CONCLUSION/CONCLUSIONS:When interpreting pelvic CT for trauma, DECT-generated BME maps increased diagnostic confidence without changing detection rates.

PURPOSE/UNASSIGNED:To assess correlation of pre-operative symptoms, labral damage and chondrolabral junction pathology on MRI with intra-operative findings in patients undergoing hip arthroscopy for femoroacetabular impingement (FAI). METHODS/UNASSIGNED:Consecutive patients with FAI treated surgically were included. Data were collected on patient demographics and preoperative clinical outcome measures. Three radiologists performed retrospective independent reviews of pre-operative MRIs in 96 hips. The presence of cartilage fraying, chondrolabral separation, labral tear pattern (intrasubstance, linear, complex), chondral flap, cartilage delamination, and ligamentum teres (LT) pathology (degeneration/partial or complete tear) were recorded on preoperative MRI and intraoperatively during arthroscopy. Inter-reader and inter-method agreement were measured using weighted-Cohen's or Fleiss'-kappa, or Kendall's coefficient. Associations between MRI and arthroscopic findings and preoperative modified-Harris-Hip-Score (mHHS) and Non-Arthritic-Hip-Score (NAHS) were assessed using Mann-Whitney-U or Kruskal-Wallis test. RESULTS/UNASSIGNED:All readers detected lower rates of chondrolabral separation, cartilage delamination, and chondral flap, and higher rates of LT tear on MRI compared to arthroscopy. Linear tears were the most common tear pattern detected by readers on MRI (29%-50%) and arthroscopy (71%). The inter-reader agreement was moderate for LT findings and fair for remaining MRI variables. Between MRI and arthroscopy, there was moderate agreement for labral fraying for one reader (k = 0.303, 95% CI[0.106-0.501], p = 0.004) and fair agreement for labral tear pattern for one reader (k = 0.187, 95% CI[0.037-0.337], p = 0.006). There was poor-to-no agreement between MRI and arthroscopy for the remaining MRI variables for all readers (p = 0.05). Preoperative mHHS and NAHS scores demonstrated no significant association with preoperative MR or intraoperative findings (p > 0.05). CONCLUSION/UNASSIGNED:MRI labral and chondrolabral findings in patients with FAI underestimated the intraoperative pathology identified during hip arthroscopy and were not associated with preoperative patient reported outcome measures. LEVEL OF EVIDENCE/UNASSIGNED:III (retrospective case series).

The abscopal effect is a rare but important phenomenon in which targeted therapy of the primary tumor, mainly radiation therapy, leads to the regression of malignant cells at distant sites from the primary tumor and outside the field of treatment. Radioembolization is a developing area of interventional oncology, typically involving microscopic radioactive spheres loaded with yttrium-90. The abscopal effect on distant bone metastases has been previously reported in patients following palliative radiotherapy; however, it has also been observed with more targeted radiation treatments, such as yttrium-90, primarily outside the musculoskeletal system. Musculoskeletal radiologists should be familiar with the abscopal effect, as the indications for radiation therapy are on the rise, and recent advancements in immune therapy have resulted in the induction of the abscopal effect. Herein, we present a case of the abscopal effect in musculoskeletal metastatic disease following targeted radioembolization. We also review the literature on the abscopal effect involving metastatic bone lesions resulting from different types of cancer therapy. Finally, we present recent advancements in cancer treatment with the aim of utilizing this effect.

OBJECTIVE:To assess the correlation of pre-operative symptoms, pre-operative diagnostic imaging for cartilage loss, and intra-operative cartilage findings in patients undergoing hip arthroscopy for femoroacetabular impingement syndrome. MATERIALS AND METHODS/METHODS:Three radiologists performed retrospective independent reviews of pre-operative MRIs in 96 hips for acetabular/femoral cartilage loss utilizing a simplified "high-low" classification and the International Cartilage Repair Society grading system. Severity of supra-foveal central femoral head cartilage loss was separately noted. Pre-operative radiographs were graded using the Tonnis and Kellgren-Lawrence systems and for central joint space narrowing. Pre-operative patient symptoms were prospectively gathered utilizing the Nonarthritic Hip Score and the modified Harris Hip Score. Intra-operatively, cartilage loss was recorded using the Outerbridge system. RESULTS: CONCLUSION/CONCLUSIONS:Despite MRI underestimation of cartilage loss, the very weak-to-weak correlation of clinical symptoms with pre-operative imaging and intra-operative findings emphasizes the importance of MRI in pre-operative evaluation.

RATIONALE AND OBJECTIVES/OBJECTIVE:Multiple modalities exist for diagnosing ulnar neuropathy at the elbow (UNE), including electrodiagnostic testing (EDX), ultrasound (US), and magnetic resonance imaging (MRI), with no consensus on the optimal strategy. This study's objective was to determine the most cost-effective diagnostic strategy in patients with suspected UNE. MATERIALS AND METHODS/METHODS:We developed a decision analytic model from the U.S. healthcare perspective over a 1-year time horizon. Our hypothetical population comprised 56-year-old males with medial elbow pain and/or paresthesias radiating to the hand, without weakness. We compared incremental cost-effectiveness and total net monetary benefit (NMB) of single-modality strategies (EDX, US, MRI) and multimodality strategies (combinations of US/MRI, EDX/US, EDX/MRI). Input probabilities and utility values were obtained from the literature, and costs from Centers for Medicaid & Medicare Services and institutional data. The primary outcome was quality-adjusted life years (QALYs). Willingness-to-pay threshold was $100,000. RESULTS:The diagnostic strategy utilizing US first, followed by MRI, was favored with the highest total QALYs, .935, and total NMB, $92,667. EDX and US single-modality strategies were less favorable, with lower total QALYs, .894 and .906, respectively, and lower total NMB, $88,866 and $90,022. Other diagnostic strategies were excluded by absolute or extended dominance. One-way sensitivity analyses found model results sensitive to the utility of UNE recovery, but otherwise robust over a range of costs/probabilities. CONCLUSION/CONCLUSIONS:Our cost-effectiveness analysis suggests an initial US, then MRI is the most cost-effective strategy in the workup of patients with suspected UNE.

Imaging plays an important role in the workup of musculoskeletal infection, in conjunction with clinical history and physical exam. There are multiple imaging modalities that can be of clinical utility in the setting of suspected infection, each with their own benefits and limitations. Radiography is a low-cost, accessible modality providing a broad osseous overview, but can be insensitive for early osteomyelitis. Ultrasound plays a more limited role in the workup of musculoskeletal infection, but can be useful in the pediatric population or for real-time guidance for joint and soft tissue aspirations. Computed tomography (CT) plays an important role in the timely and accurate diagnosis of critically ill patients in the emergency setting. Its superior soft tissue characterization allows for diagnosis of abscesses, and it can help confirm the clinical diagnosis of necrotizing fasciitis when soft tissue gas is present. Magnetic resonance imaging (MRI) is often the modality of choice in the diagnosis of infection, as its superior contrast resolution allows for clear delineation of the presence and extent of both soft tissue infection and osteomyelitis. Additionally, the use of intravenous contrast and advanced imaging sequences such as diffusion weighted imaging (DWI) further increases the diagnostic utility of MRI in the assessment for infection. Familiarity with the diagnostic utility of each imaging modality will allow the radiologist to appropriately guide imaging workup in the setting of clinically suspected infection.

The diagnosis of prosthetic joint infection (PJI) remains challenging, despite multiple available laboratory tests for both serum and synovial fluid analysis. The clinical symptoms of PJI are not always characteristic, particularly in the chronic phase, and there is often significant overlap in symptoms with non-infectious forms of arthroplasty failure. Further exacerbating this challenge is lack of a universally accepted definition for PJI, with publications from multiple professional societies citing different diagnostic criteria. While not included in many of the major societies' guidelines for diagnosis of PJI, diagnostic imaging can play an important role in the workup of suspected PJI. In this article, we will review an approach to diagnostic imaging modalities (radiography, ultrasound, CT, MRI) in the workup of suspected PJI, with special attention to the limitations and benefits of each modality. We will also discuss the role that image-guided interventions play in the workup of these patients, through ultrasound and fluoroscopically guided joint aspirations. While there is no standard imaging algorithm that can universally applied to all patients with suspected PJI, we will discuss a general approach to diagnostic imaging and image-guided intervention in this clinical scenario.

OBJECTIVE:Shear wave elastography (SWE) was used to quantify change in upper extremity muscle stiffness in patients with unilateral spastic cerebral palsy (USCP) following botulinum toxin A (BTX-A) therapy. We hypothesized that SWE measures would decrease following ultrasound-guided BTX-A injection, and correlate with functional improvement. METHODS:SWE measures of BTX-A treated muscles were recorded immediately pre-injection, and at 1-, 3- and 6-months post-injection. At the same timepoints, functional assessment was performed using the Modified Ashworth Scale (MAS), and passive and active range of motion (PROM and AROM) measures. Correlation of SWE with MAS, PROM and AROM, as well as the relationship between change in SWE and change in MAS, PROM and AROM was determined using Spearman's rank correlation coefficient and generalized estimating equation modeling. RESULTS:16 muscles were injected and longitudinally assessed. SWE and MAS scores decreased following BTX-A injection (p = 0.030 and 0.004, respectively), reflecting decreased quantitative and qualitative muscle stiffness. Decreased SWE reached statistical significance at 1- and 3-months, and 1-, 3- and 6-months for MAS. When comparing relative change in SWE to relative change in AROM, larger change in SWE strongly correlated with positive change in AROM (p-value range:<0.001-0.057). BTX-A responders also demonstrated lower baseline SWE (1.4 m/s) vs. non-responders (1.9 m/s), p = 0.035. CONCLUSION/CONCLUSIONS:Ultrasound-guided BTX-A injections in patients with USCP resulted in decreased quantitative and qualitative muscle stiffness. Strong correlation between change in SWE and AROM, as well as the significant difference in baseline SWE for BTX-A responders and non-responders, suggests SWE may provide a useful tool to predict and monitor BTX-A response.

OBJECTIVE:The purpose of this technical report is to review the sonographic spectrum of abnormalities accounting for peri-articular pain after knee replacement surgery, as well as to demonstrate the clinical utility of ultrasound in the diagnosis and treatment of this subset of patients. MATERIALS AND METHODS/METHODS:Utilizing an imaging report database, we performed a search for ultrasound examinations performed by a single radiologist for knee pain after knee arthroplasty at our institution over a 10-year period. The search yielded 63 patients, whom we have categorized by causative pathology, with representative diagnostic and procedural ultrasound images selected for inclusion. RESULTS:Our search yielded multiple causes of peri-articular knee pain after arthroplasty, including medial and lateral retinacular impingement and scarring, iliotibial band or conjoined tendon irritation, popliteus tendon impingement, medial collateral ligament impingement, pes anserine bursitis, and scarring of Hoffa's fat pad. CONCLUSION/CONCLUSIONS:While knee arthroplasty is an often-successful procedure, it can be complicated by post-operative peri-articular knee pain. Ultrasound provides a valuable tool for the diagnosis of painful peri-articular knee pathology, as it allows for both static and dynamic evaluation, as well as direct correlation with patient symptoms, and is not confounded by the metal components. In addition to its diagnostic utility, ultrasound can also guide diagnostic and/or therapeutic injections of anesthetic and corticosteroid. Given these advantages, ultrasound is an important tool in managing the painful post-arthroplasty knee.