Abstract Objective: To evaluate musculoskeletal ultrasound (MSUS) as a screening tool for rheumatoid arthritis (RA) and osteoarthritis (OA) patients in a rheumatology-screening program. Patients and methods: To raise awareness for rheumatic diseases, a mobile rheumatology office was deployed in different cities of Germany (“Rheuma-Truck”). Standardized questionnaire assessment, testing for rheumatoid factor and citrullinated peptide antibodies and medical student driven MSUS of the clinically dominant hand/foot including wrist, MCP-II, -III, -V, PIP-II, -III, MTP-II and -V were offered free of charge to the population. In case of suspicious results, a rheumatologist was consulted. Results: In MSUS, 192 of 560 selected volunteers (aged 18–89, mean 52.7 years; 72.9% female) had suspicious findings including synovitis or erosions primarily affecting the MTP-II (11.8%), dorsal wrist (8.9%), and MCP-II (7%). 354 of the 560 volunteers further visited a rheumatologist of whom 76 were diagnosed with RA. According to the ‘US7 Score’, a sum scores ≥ 5 was significantly predictive for RA (odds ratio (OR) 5.06; confidence interval (CI) 0.83–35.32). 313 volunteers displayed signs of OA including osteophytes, while MCP-II (36.2%), MCP-III (14.8%), and the wrist (10.5%) were mostly affected. Diagnosis of RA was favoured over OA if the wrist (OR 4.2; CI 1.28–13.95), MTP-II (OR 1.62; CI 1.0–2.6), and MCP-V (OR 2.0; CI 1.0–3.8) were involved. Conclusion: Medical student driven MSUS by the ‘US7 Score’ can facilitate diagnosis of RA in rheumatology-screening programs due to the level of the score and the affected joints. A high rate of unknown OA signs was detected by MSUS. A mobile rheumatology office displays an opportunity to screen patients for RA and OA.

In 1992 Unser and colleagues proved that the sequence of normalized and scaled B-splines Bm tends to the Gaussian function as the order m increases, [1]. In this article the result of Unser et al. is extended to the derivatives of the B-splines. As a consequence, a certain sequence of wavelets defined by B-splines, tends to the famous Mexican hat wavelet. Another consequence can be observed in the continuous wavelet transform (CWT) of a function analyzed with different B-spline wavelets.