Purpose This study examined the impact of the COVID-19 pandemic on emergency department CT use for acute nontraumatic abdominal pain, to better understand why imaging volume so drastically decreased during the COVID-19 pandemic. Methods This was a retrospective review of emergency imaging volumes from January 5 to May 30, 2020. Weekly volume data were collected for total imaging studies, abdominopelvic CT, and abdominopelvic CTs positive for common causes of acute nontraumatic abdominal pain. Two emergency radiology attendings scored all diverticulitis cases independently, and weekly volume data for uncomplicated and complicated diverticulitis cases was also collected. Volume data prior to and during the COVID-19 pandemic was compared, using 2019 volumes as a control. Results During the COVID-19 pandemic, overall emergency imaging volume decreased 30% compared to 2019 ( p = 0.002). While the number of emergency abdominopelvic CTs positive for appendicitis and small bowel obstruction did not significantly change during the COVID-19 pandemic, the number of cases of diverticulitis decreased significantly compared to 2019 ( p = 0.001). This reduction can be specifically attributed to decreased uncomplicated diverticulitis cases, as the number of uncomplicated diverticulitis cases dropped significantly ( p = 0.002) while there was no significant difference in the number of complicated diverticulitis cases ( p = 0.09). Conclusions Reduced emergency abdominopelvic CT volume during the COVID-19 pandemic can partially be explained by decreased imaging of lower acuity patients. This data may help formulate future strategies for imaging resource utilization with an improved understanding of the relationship between perceived imaging risk and symptom acuity.

Osteoarthritis (OA) is a leading cause of chronic disability whose mechanism of pathogenesis is largely elusive. Local inflammation is thought to play a key role in OA progression, especially in injury-associated OA. While multiple inflammatory cytokines are detected, the timing and extent of overall inflammatory activities in early OA and the manner by which joint inflammation correlates with cartilage structural damage are still unclear. We induced OA via destabilization of the medial meniscus (DMM) in NFκB luciferase reporter mice, whose bioluminescent signal reflects the activity of NFκB, a central mediator of inflammation. Bioluminescence imaging data showed that DMM and sham control joints had a similar surge of inflammation at 1-week post-surgery, but the DMM joint exhibited a delay in resolution of inflammation in subsequent weeks. A similar trend was observed with synovitis, which we found to be mainly driven by synovial cell density and inflammatory infiltration rather than synovial lining thickness. Interestingly, an association between synovitis and collagen structural damage was observed in early OA. Using Second Harmonic Generation (SHG) imaging, we analyzed collagen fiber organization in articular cartilage. Zonal differences in collagen fiber thickness and organization were observed as soon as OA initiated after DMM surgery, and persisted over time. Even at 1-week post-surgery, the DMM joint showed a decrease in collagen fiber thickness in the deep zone and an increase in collagen fiber disorganization in the superficial zone. Since we were able detect and quantify collagen structural changes very early in OA development by SHG imaging, we concluded that SHG imaging is a highly sensitive tool to evaluate pathological changes in OA. In summary, this study uncovered a dynamic profile of inflammation and joint cartilage damage during OA initiation and development, providing novel insights into OA pathology.

Wnt7a is a protein that plays a critical role in skeletal development. However, its effect on cartilage homeostasis under pathological conditions is not known. In this study, we found a unique inverse correlation between Wnt7a gene expression and that of MMP and IL-1β in individual human OA cartilage specimens. Upon ectopic expression in primary human articular chondrocytes, Wnt7a inhibited IL-1β-induced MMP and iNOS gene expression. Western blot analysis indicated that Wnt7a induced both canonical Wnt signaling and NFAT and Akt non-canonical signaling. Interestingly, inhibiting the canonical and Akt pathway did not affect Wnt7a activity. However, inhibiting the NFAT pathway impaired Wnt7a’s ability to inhibit MMP expression, suggesting that Wnt7a requires NFAT signaling to exert this function. In vivo, intraarticular injection of lentiviral Wnt7a strongly attenuated articular cartilage damage induced by destabilization of the medial meniscus (DMM) OA-inducing surgery in mice. Consistently, Wnt7a also inhibited the progressive increase of joint MMP activity in DMM animals. These results indicate that Wnt7a signaling inhibits inflammatory stimuli-induced catabolic gene expression in human articular chondrocytes and is sufficient to attenuate MMP activities and promote joint cartilage integrity in mouse experimental OA, demonstrating a novel effect of Wnt7a on regulating OA pathogenesis.

areas of the affected joint. Radiographic findings may be incorrectly found to be 'normal' in the early stages of the disease because the cartilage is not directly visualized. In this study we performed experiments with a confocal microprobe in the OA knee joint to track the delivery of therapeutically targeted compounds encapsulated in nanoparticles. This procedure allows for high quality images of a very thin focusing field. Methods: 10 weeks old male C57/Bl6 mice were used to induce OA. OA was induced by two consecutive intra articular injections of 10 ml highly purified bacterial type VII collagenase (10 U) into the right knee. As analgesic, the mice received also a subcutaneous injection of Temgesic (0.01 mg/kg body weight). To track the delivery of therapeutic compounds, PLGA based nanoparticles (NP) loaded with drug and Near Infra-Red (NIR) 800 dye were prepared with a water-in-oil-in-water double emulsion and solvent evaporation method. After characterizing with imaging techniques, 100 ml NP was injected in the mouse tail vein (iv). The NP delivery and distribution were followed by for several weeks with the Pearl Impulse imaging system (Li-Cor, Nebraska, USA) and Cellvizio 785 nm prototype fluorescence-based Confocal Laser Endomicroscopy (CLE) system (Mauna Kea, Paris, France). The Pearl Impulse is specifically optimized for whole small animal imaging while the CLE 785 nm prototype system is made to image the tissue of interest and provides real-time in vivo video sequences at cellular resolution. This system allows us to monitor in real time the delivery of a drug to a target site compound of interest within its anatomical environment in the living animal by simply to bring the flexible microprobe in contact with the tissue of interest to record real-time images of the tissue at cellular resolution. The knee joint was exposed by a superficial skin incision and a S300B with 3.3 mm resolution confocal microprobe was directly positioned onto the surface to scan the NIR 800 dye. During the scans all the mice were anesthetized with a 2% isoflurane/N 2 O/O 2 mixture. Results: CLE imaging in vivo, after induction of OA using collagenase, was performed according to the results of the whole animal fluorescent imaging and knee joint. No significant fluorescent signal was observed in the controls. The results from ex vivo fluorescent imaging of knee joint cryosections were consistent with in vivo CLE findings. Conclusions: Our study shows that targeted imaging using a fluorescently labeled NP is possible with CLE. These findings indicate that we can follow the NP loaded with drug and NIR dye in the OA knee joint at different stages of the disease. This will impact upon future clinical approaches for OA, whereby diagnosis can be determined by optical imaging.Purpose: Histopathological grading of osteoarthritis (OA) from thin tissue sections is the gold standard method in research, which has multiple known drawbacks. To capture complex three-dimensional (3D) OAinduced changes, we have previously developed a semi-aut...