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The most accurate attenuation correction in positron emission tomography (PET) is achieved by measuring a transmission scan with a rotating rod source in combination with a blank scan using the rod windowing technique. In clinical routine, however, transmission scans often have to be acquired after the administration of the radiotracer. The raw data recorded this way are biased by coincidences generated by the additional activity in the scanner's field of view. In a first approximation, these additional true coincidences can be removed by subtracting a decay-corrected emission scan from the post-injection transmission data. But there are also additional 'mixed' random events generated by the single photon fluxes from the patient activity and the rod source together. In this work, the correction for post-injection transmission data was extended to take into account the effect of the rod windowing and the 'mixed' randoms. A couple of experiments were performed to determine the reduced scanner sensitivity for the additional true and random events with active rod windowing. The resulting correction, which can be used for most tomographs without a measured random correction, was validated in a study with the EEC whole-body phantom.

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Angiosarcomas are high-grade vascular tumors associated with poor prognosis due to their aggressive nature. Occasional skeletal manifestations present commonly as osteolytic destruction. The 55-years-old patient presented in this case report had a disease-free 4 years interval between splenectomy after primary angiosarcoma of the spleen and an unusual skeletal metastatic pattern mimicking benign angiomatosis. Despite lacking radiographic evidence for a highly aggressive osseous process, the histopathological resemblance of the bone biopsy with the primary tumor manifestation and the fulminant course of disease after onset of disseminated osseous spread confirmed the malignant character of the vascular tumor. The case demonstrates the highly variable radiographic pattern and particular pathobiological behavior of vascular malignancies. [ABSTRACT FROM AUTHOR]

Recent data suggested an increased frequency of KIT aberrations in mucosal melanomas, whereas c-KIT in most types of cutaneous melanomas does not appear to be of pathogenetic importance. However, studies investigating the status of the KIT gene in larger, well-characterised groups of patients with mucosal melanomas are lacking. We analysed 44 archival specimens of 39 well-characterised patients with mucosal melanomas of different locations. c-KIT protein expression was determined by immunhistochemistry, KIT gene mutations were analysed by PCR amplification and DNA sequencing of exons 9, 11, 13, 17 and 18. c-KIT protein expression could be shown in 40 out of 44 (91%) tumours in at least 10% of tumour cells. DNA sequence analysis of the KIT was successfully performed in 37 patients. In 6 out of 37 patients (16%) KIT mutations were found, five in exon 11 and one in exon 18. The presence of mutations in exon 11 correlated with a significant stronger immunohistochemical expression of c-KIT protein (P=0.015). Among the six patients with mutations, in two patients the primary tumour was located in the head/neck region, in three patients in the genitourinary tract and in one patient in the anal/rectal area. In conclusion, KIT mutations can be found in a subset of patients with mucosal melanomas irrespective of the location of the primary tumour. Our data encourage therapeutic attempts with tyrosine kinase inhibitors blocking c-KIT in these patients. [ABSTRACT FROM AUTHOR]

The mediastinum is a unique anatomic area containing several structures and pluripotent cells that allow for the development of a range of tumours. Uncommon neoplasms of the mediastinum account for less than 10% of all mediastinal masses and include primary thymic carcinomas, neuroendocrine carcinomas, germ-cell tumours (GCTs), lymphomas, and neurogenic, endocrine, and mesenchymal tumours. Primary thymic carcinomas and neuroendocrine carcinomas, although rare, are highly malignant lesions. GCTs are thought to derive from primitive germ cells and can be classified in seminomatous and non-seminomatous GCTs. They are located predominantly in the anterior mediastinum, as are the primary mediastinal lymphomas that include Hodgkin lymphoma, large B cell lymphoma, and lymphoblastic lymphoma. Neurogenic tumours may arise from peripheral nerves, sympathetic ganglia, or rarely parasympathetic ganglia and are located predominantly in the posterior mediastinum. Endocrine tumours are the ectopic thyroid and parathyroid tumours. Mesenchymal tumours are rare tumours and no less problematic than they are in peripheral sites. The clinical, radiological, and therapeutic aspects of these tumours are reviewed. [ABSTRACT FROM AUTHOR]

A correlation is demonstrated between chronic hemodialysis using cuprophane membranes (mean duration: 13 years) and pathological fractures (n = 7 in 6 patients) after lytic bone deposits of beta 2-microglobulin amyloid (n = 13 patients). The characteristic symptom complex includes painful impingement syndrome of the shoulder, carpal tunnel syndrome, painful hip and recurrent knee effusions. The first steps of the clinical diagnostic procedure are to demonstrate lytic defects in skeletal radiographs and to verify the presence of beta 2m by biopsy or puncture. Due to reduced regeneration capacity in amyloid bone lesions the resulting surgical therapy should aim at total joint replacement or augmented osteo synthesis. Definitive operative treatment should be aspired even in the absence of manifest fractures, as the natural course of the disease is characterized by progression of the bone destruction and a continuous pain syndrome. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Presents cases of endoscopic diagnosis of tumors of the small intestine. Result of the x-ray examination of the esophagus, stomach and duodenum; Background on the patient who suffered from stomach pains; Technique used in the removal of tumor.