A case of idiopathic granulomatous mastitis mimicking breast carcinoma clinically and radiographically is reported with mammography, sonography and MR images.

Twenty patients with longstanding polyarticular rheu~ matoid arthritis (including knee involvement) were se~ lected for this study. The severity of the knee synovitis was assessed before and during treatment (with intraarticular corticosteroid injections) using clinical scores, sonography, and thermography. In all patients, the in· flammation regressed during treatment. During followup, the quantity of synovial fluid, as measured sonographically 10 days after the start of therapy, correlated Q uantification of pain and inflammation in rheumatoid arthritis is a difficult clinical problem; 1 as a result, any evaluation based on patient symptoms is fraught with error. A standardized and reproducible method of grading both the severity of disease and the response to treatment is sorely needed.1.2In the last 20 years, various methods have been proposed to assess the severity of articular involvement, including radioisotope scanningM and thermography.5-7 More recently, the use of sonography and magnetic resonance has been suggested. a-u The aim of the present study is to compare the utility of the sonographic parameters, synovial thickness and 7:561, 1988) intra-articular fluid, with the clinical and thermographic rating systems, 2.5;7 both before and during treatment of rheumatoid arthritis of the knee. MATERIALS AND METHODSSixteen women and four men aged 40 to 73 (mean 59 years) were included in this study. All patients had classical rheumatoid arthritis and were classified according to the grading system of the American Rheumatism As· sociation. u All patients had persistent and disabling knee symptoms despite control of the articular symptoms elsewhere by conventional drug therapy.The mean duration of the rheumatoid arthritis in our group was 10 years (range 2 to 26 years). The duration of the acute exacerbation of knee arthritis ranged between 8 and 52 weeks (mean 21 weeks).According to the rating system of the American Rheumatism Association, eight patients were in stage 1 and 12 were in stage 2. uThe patients were assessed on day 0 (before treatment) and at 10 days and three months after treatment

The visibility of micro calcifications is a determining factor for digital mammography. To address the problem of quantification, we developed a procedure to simulate micro calcifications into real mammograms. First, the shapes, sizes and x-ray transmission coefficients of real micro calcifications were derived from the appearance of biopsy specimens in the raw data of magnified, digital images acquired at 27 kVp and Mo/Mo anode-filter combination. This allowed us to create "ideal templates" of micro calcifications. The x-ray transmissions of the real micro calcifications values were expressed in Al-equivalent thickness. This made it possible to recalculate the x-ray transmission characteristics of a particular ideal template for other x-ray beam qualities. Extra corrections for differences in spatial resolution were based on the presampled two-dimensional modulation transfer functions and on the difference in pixel size. Three radiologists compared the appearance of real and simulated micro calcifications in a two-alternative forced choice (2AFC) evaluation. They perceived no differences between real and simulated lesions. Preliminary results show that it is possible to simulate micro calcifications with well defined characteristics that are indistinguishable from real ones. It should be noted, however, that the full potential of the approach has not been proven. In future work, these templates may be useful to evaluate particular aspects of digital mammograms, such as the effects of processing and of viewing conditions on the visibility of micro calcifications.

This paper gives an overview of test procedures developed to assess the performance of full field digital mammography systems. We make a distinction between tests of the individual components of the imaging chain and global system tests. Most tests are not yet fully standardised. Where possible, we illustrate the test methodologies on a selenium flat-panel system.

These data using clinical images confirm results found in simple QA tests for many mammography systems that detectability falls as breast thickness increases. Results obtained with the AEC setup for constant detectability above 49 mm showed an increase in lesion detection with compressed breast thickness, bringing detectability of lesions to the same level.

• Performance parameters showed no major differences after digitalisation to CR or DR. • Transition from SFM to CR results in a higher mean glandular dose. • Transition from SFM to DR results in a lower mean glandular dose.

In order to quantify the clinical quality of full-field digital mammography, a set of image quality parameters is developed. The set consisted of 12 image quality criteria and 8 physical characteristics of the image. The first set interrogates the visibility of anatomical structures and typical characteristics of a digital image, such as noise and saturation of dark and white areas. The second set of criteria evaluates contrast, sharpness and confidence with the representation of masses, microcalcifications and the image. The use of these criteria is reported in a retrospective study, in which the impact of dose on the radiological quality of digital mammograms is evaluated. Fifty patients acquired in a low-dose mode were retrieved and compared with 50 patients acquired in a dose mode that was set 41% higher. The dose affects, more than expected, contrast and sharpness of the image, whereas the visibility of the anatomical structures remains unchanged. With these parameters, quantification of the image quality is possible; however, because of subjectivity of the parameters, only intra-observer comparison and evaluation of the individual parameters rather than the overall results are advised. Together with physical tests of image quality, critical radiological evaluation of the quality should be included in the acceptance process of digital mammography.

Full field digital mammography (FFDM) has advantages over screen-film mammography (SFM), but some important challenges remain. The first challenge is related to the specific characteristics of FFDM. It remains unclear, which shape and limiting values of the modulation transfer function have the most influence on the performance of a detector, such as the effect of the image display on the overall image quality and the effect of processing on cancer detection. In order to assess the image quality of FFDM, we have set up a scoring system. The second challenge is related to screening mammography: is the quality of an image the same when it is viewed on different monitors and with different processing algorithms? Is Computer Aided Diagnosis necessary in a screening environment? In FFDM, the effect of different detectors, processing and display possibilities on the image and on cancer detection are not clearly investigated.