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This paper studies the decomposition of the time reversal operator (DORT, by the French acronym) technique for microwave breast lesion classification. We apply the finitedifference time-domain (FDTD) method to a realistic numerical breast phantom where lesion-like targets are artificially introduced, and obtain the multistatic data matrix (MDM) for a particular antenna array configuration. Then, the singular value decomposition (SVD) of this matrix is derived for different targets, which represent malignant and benign lesions. We show that the singular value spectrum can assist in classifying these targets as malignant or benign, especially in the case where contrast-enhanced agents can be employed to allow the analysis of differential backscatter data.

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INTRODUCTION: To justify economically the use of autologous blood re-infusion after total knee replacement surgery compared with vacuum drains. To determine if the patients using autologous re-infusion units have a reduced allogenic blood transfusion requirement and hospital stay. PATIENTS AND METHODS: Prospectively, 50 patients undergoing primary unilateral total knee replacements with autologous re-infusion units were studied. They were matched for age, sex, type of prosthesis and the month in which surgery took place to a second group undergoing the same surgery with vacuum drains. The results for the second group were obtained retrospectively from the notes. The outcome measures were the need for allogenic blood transfusion and length of postoperative hospital stay. RESULTS: The use of re-infusion units reduced the need for postoperative allogenic blood transfusion from 28% to 4% in total knee replacement surgery. The cost of using re-infusion units was the same as vacuum drains. Overall, the autologous re-infusion patients were discharged 2 days earlier (99% confidence interval). CONCLUSIONS: Re-infusion units are no more expensive than vacuum drains. In addition, autologous blood has many clinical benefits compared to allogenic blood. Re-infusion may shorten the hospital stay for patients undergoing total knee replacement surgery.

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Acetabular cement extrusion (CE) is a common finding after total hip arthroplasty, but the incidence is unclear from the literature, and there is no accepted way of measuring it. We report a retrospective observational study of 100 patients (25 consecutive patients from each of 4 consultants, 112 hips) to determine the site and incidence of CE on postoperative radiographs, and to measure its area and the maximum distance of the extruded cement from the edge of the cement mantle. We found that 50 of 112 (44.6%) hips showed evidence of CE, with a 15.2% incidence of CE > 200 mm(2).

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We present this case of an unusual recurrence of a periosteal osteosarcoma in the distal right tibia 2 years after a successful proximal right tibia primary periosteal osteosarcoma excision with a successful fibular graft. This recurrence lead to a right below-knee amputation.

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A 78-year-old man presented with a mass on his right forearm. A 5 x 4 x 3 cm(3) mass was excised en bloc with extensions along the course of the cephalic vein and its tributaries. Histological analysis revealed the mass to be a high-grade leiomyosarcoma arising within the cephalic vein. The tumour was controlled locally and distally until the patient died 10 months later, from an unrelated illness. This is the first reported case of a venous leiomyosarcoma of the cephalic vein.

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We report here a young male athlete who had an acute myocardial infarction after strenuous exercise. Coronary angiography clearly demonstrated thrombus formation within a prominent myocardial bridge. Periarterial resection surgery was performed, which resulted in resolution of the angiographic "milking" effect of muscle bridge. Our observation, along with previous reports, suggests that myocardial bridges should be added to the list of known causes of sudden death or myocardial infarction in young persons after strenuous exercise. Thrombus formation within a myocardial bridge may be a potential mechanism whereby this anatomic curiosity may cause a tragic clinical event.

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The feasibility and safety of running an elective orthopaedic service at the weekend is demonstrated. Weekend timing of such surgery appears to be very popular with patients. The cost of not assessing patients pre-operatively in terms of theatre time lost is shown.

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Five patients undergoing routine total knee replacement received standard antibiotic prophylaxis of 1000 mg of iv cefamandole and also regional administration of 750 mg of cefuroxime. Regional dosing was carried out at the start of the operation, following the application of a mid-thigh tourniquet, by administration into a foot vein. Samples of bone and fat were collected during the operation and assayed for cefuroxime and cefamandole by HPLC analysis. The mean cefuroxime bone (133.1 mg/l) and fat (88.4 mg/l) levels following regional administration were significantly higher (P less than 0.001) than the mean cefamandole bone (9.1 mg/l) and fat (9.8 mg/l) levels following systemic dosing. The possibility of administration of prophylaxis by the regional route is suggested.

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There is a trend away from amputation for limb cancer; salvage procedures are becoming more widespread. We describe one case of interscapulothoracic resection of the shoulder and discuss methods of maximising the residual function of the arm. The procedure is recommended for patients with the correct indications.

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Vacuolization of the polymorphonuclear leukocyte (PMN) has generally been regarded as an indication of bacterial infection and has been particularly useful in diagnosing septicemia. In an effort to predict septicemia, peripheral blood smears from 69 febrile children were examined and systematically scored for severity of vacuolization. Thirteen children had remarkable vacuolization compared to the others. These 13 included only five children with bacterial illnesses and only one of the seven children with septicemia. Our finding that PMN vacuolization was neither diagnostic of septicemia nor predictive of bacterial infection suggests that the specificity of the link between vacuoles and bacteremia needs to be reassessed.

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Acute renal insufficiency developed in three patients receiving chemotherapy for tuberculosis. It is proposed that acute diffuse interstitial nephritis related to the drugs was responsible for the renal injury. Recovery of renal function was slow and incomplete. Physicians administering chemotherapy to patients with tuberculosis must be aware of the potential nephrotoxicity of the common treatment regimens.

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