Imaging approach to prosthetic joint 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.

Approach to imaging modalities in the setting of suspected infection.

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.

Utilization of shear wave elastography to quantify and predict response to upper extremity botulinum toxin injections in patients with cerebral palsy: A pilot study.

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: 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.

Deep-learning-reconstructed high-resolution 3D cervical spine MRI for foraminal stenosis evaluation.

OBJECTIVE: To compare standard-of-care two-dimensional MRI acquisitions of the cervical spine with those from a single three-dimensional MRI acquisition, reconstructed using a deep-learning-based reconstruction algorithm. We hypothesized that the improved image quality provided by deep-learning-based reconstruction would result in improved inter-rater agreement for cervical spine foraminal stenosis compared to conventional two-dimensional acquisitions. MATERIALS AND METHODS: Forty-one patients underwent routine cervical spine MRI with a conventional protocol comprising two-dimensional T2-weighted fast spin echo scans (2 axial planes, 1 sagittal plane), and an isotropic-resolution three-dimensional T2-weighted fast spin echo scan reconstructed over a 4-h time window with a deep-learning-based reconstruction algorithm. Three radiologists retrospectively assessed images for the degree to which motion artifact limited clinical assessment, and foraminal and central stenosis at each level. Inter-rater agreement was analyzed with weighted Fleiss's kappa (k) and comparisons between two-dimensional and three-dimensional sequences were performed with Wilcoxon signed-rank test. RESULTS: Inter-rater agreement for foraminal stenosis was "substantial" for two-dimensional sequences (k = 0.76) and "excellent" for the three-dimensional sequence (k = 0.81). Agreement was "excellent" for both sequences (k = 0.85 and 0.83) for central stenosis. The three-dimensional sequence had less perceptible motion artifact (p ≤ 0.001-0.036). Mean total scan time was 10.8 min for the two-dimensional sequences, and 7.3 min for the three-dimensional sequence. CONCLUSION: Three-dimensional MRI reconstructed with a deep-learning-based algorithm provided "excellent" inter-observer agreement for foraminal and central stenosis, which was at least equivalent to standard-of-care two-dimensional imaging. Three-dimensional MRI with deep-learning-based reconstruction was less prone to motion artifact, with overall scan time savings.

Diagnostic ultrasound and ultrasound-guided injections for peri-articular pain after knee replacement.

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: 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: 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.

Imaging of Emerging Infectious Diseases.

PURPOSE OF REVIEW: Emerging infectious diseases have seen a record increase in prevalence, and understanding their management is critical in an increasingly global community. In this paper, we review current literature detailing the role of radiology in the diagnosis and treatment of the Ebola (EVD), Zika (ZVD), Chikungunya (CHIKF), H1N1, Middle East Respiratory (MERS), and Severe Acute Respiratory Syndrome (SARS) viruses. RECENT FINDINGS: Complex protocols are required to safely use portable imaging in EVD to prevent nosocomial spread of disease. In ZVD, antenatal ultrasound can detect fetal abnormalities early, allowing implementation of care and support to affected families. Imaging is useful in assessing the extent of involvement of chronic CHIKF and monitoring treatment effect. Chest radiography and CT play a more direct role in the diagnosis and monitoring of the viral infections with primarily respiratory manifestations (H1N1, MERS, and SARS). SUMMARY: Radiology plays a variable role in emerging infectious diseases, requiring an understanding of disease transmission and safe imaging practices, as well as imaging features that affect clinical management.

Outcomes of Preoperative MRI-Guided Needle Localization of Nonpalpable Mammographically Occult Breast Lesions.

OBJECTIVE: MRI-guided needle localization allows access to MRI-detected mammographically occult breast lesions that are not amenable to MRI-guided biopsy. The purpose of this study was to examine the safety and outcomes of MRI-guided needle localization. MATERIALS AND METHODS: Ninety-nine consecutive breast lesions that underwent preoperative MRI-guided needle localization were identified. Clinical indications for breast MRI, reasons for performing MRI-guided needle localization, and surgical pathology results were recorded. Lesion characteristics, procedure time, and complications were assessed. RESULTS: Of 99 lesions, 60 (60.6%) were in a location inaccessible for MRI biopsy, necessitating MRI-guided needle localization. Histologic evaluation revealed 38 (38.4%) carcinomas, 31 (31.3%) high-risk lesions, and 30 (30.3%) benign lesions. Carcinoma was more likely to be found in women with known cancer (31/61 [50.8%]; p = 0.003) than in women undergoing imaging for high-risk screening (2/18 [11.1%]) or problem solving (6/20 [30%]). Masses (p = 0.013) and foci (p < 0.001) were more likely to be malignant than were lesions with nonmass enhancement. Foci were significantly more often malignant compared with all other lesion types (9/10 [90%]; p < 0.001). The mean (± SD) procedure time was 32.9 ± 9.39 minutes. All lesions were occult on specimen radiographs. There were no procedure-related complications. CONCLUSION: The positive predictive value of MRI-guided needle localization (38.4%) is comparable to that of mammography- and tomosynthesis-guided localizations and is highest in women with a known diagnosis of cancer. It is highly accurate in targeting small enhancing lesions, thereby improving surgical management. MRI-guided needle localization is a safe, accurate, and time-efficient procedure.

WNT10B/ß-catenin signalling induces HMGA2 and proliferation in metastatic triple-negative breast cancer.

Wnt/ß-catenin signalling has been suggested to be active in basal-like breast cancer. However, in highly aggressive metastatic triple-negative breast cancers (TNBC) the role of ß-catenin and the underlying mechanism(s) for the aggressiveness of TNBC remain unknown. We illustrate that WNT10B induces transcriptionally active ß-catenin in human TNBC and predicts survival-outcome of patients with both TNBC and basal-like tumours. We provide evidence that transgenic murine Wnt10b-driven tumours are devoid of ERα, PR and HER2 expression and can model human TNBC. Importantly, HMGA2 is specifically expressed during early stages of embryonic mammogenesis and absent when WNT10B expression is lost, suggesting a developmentally conserved mode of action. Mechanistically, ChIP analysis uncovered that WNT10B activates canonical ß-catenin signalling leading to up-regulation of HMGA2. Treatment of mouse and human triple-negative tumour cells with two Wnt/ß-catenin pathway modulators or siRNA to HMGA2 decreases HMGA2 levels and proliferation. We demonstrate that WNT10B has epistatic activity on HMGA2, which is necessary and sufficient for proliferation of TNBC cells. Furthermore, HMGA2 expression predicts relapse-free-survival and metastasis in TNBC patients.