Objective. Varus and valgus malalignment increase the risk of medial and lateral osteoarthritis (OA) progression, respectively. The impact of a mechanical factor such as alignment depends not only on the factor itself, but also on the state of the joint. The lessdamaged joint of mild OA may be less vulnerable to malalignment effects than the more-damaged joint of moderate OA. Our goal was to explore the impact of alignment on subsequent progression of knee OA according to the baseline stage of disease.Methods. Two hundred thirty patients with knee OA (defined by the presence of osteophytes and symptoms) recruited from the community underwent assessment of both lower limbs at baseline and at an 18-month followup. Alignment was measured on a full-limb radiograph as the angle made by the intersection of the femoral and tibial mechanical axes. Compartmentspecific progression was defined as an increase between baseline and 18 months in the grade of severity of joint space narrowing on radiographs of semiflexed knees taken after fluoroscopic confirmation of position. Knees were grouped according to their baseline stage of OA as Kellgren/Lawrence (K/L) grades 0-1, 2, or 3. Progression odds ratios were estimated from logistic regression using generalized estimating equations.Results. There were 377 K/L grade 0-3 knees in 230 subjects (173 women and 57 men, mean age 64.0 years, mean body mass index 30.4 kg/m 2 ) in this longitudinal study. In knees with mild OA (K/L grade 2), the odds of 18-month progression in the medial compartment were significantly increased 4-fold by varus alignment at baseline. In K/L grade 2 knees, the odds of lateral progression were increased 2-fold by valgus alignment (approaching significance). In knees with moderate OA (K/L grade 3), the risk of progression was comparably increased by varus or valgus alignment (10-fold).Conclusion. While some effect of malalignment was suggested at almost all stages of knee OA examined, the impact of varus or valgus malalignment on the odds of OA progression over the ensuing 18 months was greater in knees with moderate (K/L grade 3) OA at baseline, possibly due to greater joint vulnerability with some contribution from slightly more severe malalignment.

The goals and current efforts of the Radiological Society of North America Radiology Reporting Committee are described. The committee's charter provides an opportunity to improve the organization, content, readability, and usefulness of the radiology report and to advance the efficiency and effectiveness of the reporting process.

Image annotation and markup are at the core of medical interpretation in both the clinical and the research setting. Digital medical images are managed with the DICOM standard format. While DICOM contains a large amount of meta-data about whom, where, and how the image was acquired, DICOM says little about the content or meaning of the pixel data. An image annotation is the explanatory or descriptive information about the pixel data of an image that is generated by a human or machine observer. An image markup is the graphical symbols placed over the image to depict an annotation. While DICOM is the standard for medical image acquisition, manipulation, transmission, storage, and display, there are no standards for image annotation and markup. Many systems expect annotation to be reported verbally, while markups are stored in graphical overlays or proprietary formats. This makes it difficult to extract and compute with both of them. The goal of the Annotation and Image Markup (AIM) project is to develop a mechanism, for modeling, capturing, and serializing image annotation and markup data that can be adopted as a standard by the medical imaging community. The AIM project produces both human- and machine-readable artifacts. This paper describes the AIM information model, schemas, software libraries, and tools so as to prepare researchers and developers for their use of AIM.

Does the subject of this series of articles intrigue you but you're not sure if the topics covered really apply to you and your practice? Before you read another word, go to the end of this introduction and seriously try to answer the questions posed there. If you answer "yes" to questions 1, 4, 5, 6, and 7, you need to read these articles.

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