CT of metal implants: reduction of artifacts using an extended CT scale technique.

PURPOSE: The purpose of this work was to use an extended CT scale technique (ECTS) to reduce artifacts due to metal implants and to optimize CT imaging parameters for metal implants using an experimental model. METHOD: Osteotomies were performed in 20 porcine femur specimens. One hundred cobalt-base screws and 24 steel plates were used for osteosynthesis in these specimens. Artificial lesions were produced in 50 screws, such as osteolysis near the screws (mimicking lysis due to infection, tumor, or loosening), displacement of the screws, as well as fractures of the screws. All specimens were examined using eight different CT protocols: four conventional (CCT) and four spiral (SCT) CT protocols with different milliampere-second values (130 and 480 mAs for CCT, 130 and 300 mAs for SCT), kilovolt potentials (120 and 140 kVp), and slice thicknesses (2 and 5 mm). The images were analyzed by three observers using a standard window (maximum window width 4,000 HU) and ECTS (maximum window width 40,000 HU). Receiver operating characteristic analysis was performed, and image quality was assessed according to a five level scale. RESULTS: Metal artifacts were significantly reduced using ECTS (p < 0.05). The highest diagnostic performance was obtained using ECTS with the thinnest slice thickness. Metal artifacts were more pronounced using SCT. In this experimental model, exposure dose and kilovolt potential had no significant impact on diagnostic performance (p > 0.05). CONCLUSION: ECTS improved imaging of metal implants. In this study, no significant effects of exposure dose and kilovolt potential were noted. Metal artifacts were more prominent using SCT than using CCT.

[Percutaneous therapy of osteoid osteoma]. / Zur perkutanen Therapie des Osteoidosteoms.

Osteoid osteomas are tumors with intense clinical symptoms and extensive reactive bone changes far exceeding the volume of the lesion itself. Because of their small size they can be approached by minimally invasive surgical procedures. We treated ten symptomatic patients with osteoid osteomas (n 6 hip point, n 1 iliac bone, n 1 femoral diaphysis, n 2 tibial diaphysis) by excision of the nidus with a 3-mm Harlow-Wood needle using a percutaneous CT-guided approach. Seven patients with residual tumor were treated with either thermocautery (n 2) or sclerosis with 1 ml of 96% ethanol (n 5). Six patients had instant and constant relief (3 years' observation) of their pain. In two patients a second transcutaneous intervention was successful. Only two patients needed open resection. Compared with the invasive open resection of the tumors, sometimes even putting the stability of the femoral neck at risk, transcutaneous CT-guided enucleation of the nidus of the osteoid osteoma with additional sclerotherapy is a good alternative method, especially in the region of the femoral neck.

Percutaneous bone biopsy, techniques and indications.

In the first part of this article we discuss some special technical aspects of percutaneous bone biopsy (PBB). But our main intention is to illuminate the critical indication of PBB against the background of the diagnostic and clinical utility. Reliable indications for PBB are: lytic metastases, solitary lytic lesions in a patient with known primary tumour and infection. Sclerotic metastases and vertebral compressions, on the other hand, have a lower diagnostic utility. Negative biopsies must be interpreted carefully and repeated if considered to be nonrepresentative The indication for percutaneous biopsy of primary bone tumours remains doubtful. Most of them require open biopsy.

Esterase-30 (ES-30) of the house mouse: biochemical characterization and genetics of a new carboxylesterase isozyme linked to cluster-2 loci on chromosome 8.

A new carboxylesterase isozyme (EC 3.1.1.1), designated ES-30, is described in mouse liver. Two phenotypes were distinguished, ES-30A, a possible null type, was found in SPE/Pas and in other lines derived from Mus spretus, and ES-30B was found in BALB/cJ and other laboratory inbred strains. ES-30B is characterized by a distinct electrophoretic band when stained using 5-bromoindoxyl acetate as the substrate. After isolation and purification from other esterases by ion-exchange chromatography and molecular sieving, the molecular mass was estimated by two independent methods to be 62 and 64 kDa, respectively. The activity of ES-30B is higher in adult males than in females and can be stimulated in vivo by testosterone. The distribution of phenotypes on the progeny of a backcross series suggests a separate locus, Es-30, with the allele a for absence and b for presence of the isozyme. Locus Es-30 is shown to be closely linked to Es-2 and to Es-7 of cluster-2 on chromosome 8. The gene order Es-9--Got-2--(Es-2, Es-7, Es-30) is suggested.

[Percutaneous bone biopsy. Critical analysis of 153 patients]. / Zur perkutanen Knochenbiopsie. Kritische Analyse von 153 Patienten.

The value of transcutaneous bone biopsy was critically examined in a retrospective study of 153 patients with various bone diseases. A comparison of the clinical, radiological and histological findings gave reliable results in approximately 82%. Specific results were worse in inflammatory processes than in those involving tumours. The results of biopsy were of particular interest where clinical and radiological examinations pointed to an isolated bone metastasis in cases of known and unknown primary tumours. The advantages of the method are discussed with regard to the patient's well-being and to cost.

[Results and assessment of computerized tomography in the initial diagnosis in polytrauma]. / Ergebnisse und Beurteilung der Computertomographie in der Erstdiagnostik beim Polytrauma.

In a period from 1984 to 1986 (T-scan was used as acute diagnostic in 74 polytraumatized patients. The patients were brought by emergency car or helicopter during or shortly after shock treatment directly to the computerized tomography. In all patients several regions of the body (head, thorax, abdomen, extremities) were examined in the (T-scan. Nearly two third of the patients (n = 58) were examined because of an uncertain abdominal trauma. In 27 of these patients pathological results were found, which have been followed by immediate laparotomy. Besides the high efficiency one more advantage of the method is its non-invasivity.

[Clinical aspects and radiology of histiocytosis X in the skeleton--a retrospective study of 18 patients]. / Zur Klinik und Radiologie der Histiozytose X am Skelett--eine retrospektive Studie an 18 Patienten.

The present paper presents the clinical and radiological findings from a retrospective study of 18 children suffering from histiocytosis with skeletal involvement (20 lesions) treated between 1971 and 1983. The different forms of manifestation on the skull, vertebral column, and long bones are described and problems of differential diagnosis discussed. Possible forms of therapy are considered.

Identification and development of a genetically closely-linked carboxylesterase family of the mouse liver.

Six carboxylesterase isozymes (viz. ES-1, ES-6, ES-9, ES-20, ES-22 and ES-24), governed by esterase gene cluster 1 on chromosome 8 of the house mouse, were identified electrophoretically in liver supernatants using their biochemical, genetic and developmental characteristics. ES-1 and ES-20 were expressed as liver-specific forms. The peri- and postnatal development of the six isozymes indicated that they were individually regulated at the genetic level, although the isozymes were regulated as a group when compared to genetically unrelated esterases. The concept of evolutionary divergence following repeated gene duplication of an ancestral esterase structural gene was extended to cover divergence of the temporal (regulatory) genes associated with the multigene family. Allelic variation of the temporal genes was more limited than that of the corresponding structural genes.