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  • 1
    ISSN: 1619-7089
    Keywords: Key words: l-3-[I-123]iodo-α-methyltyrosine ; Dosimetry ; Brain tumours ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The synthetic amino acid l-3-[123I]iodo-α-methyltyrosine (IMT) is currently under clinical evaluation as a single-photon emission tomography (SPET) tracer of amino acid uptake in brain tumours. So far, dosimetric data in respect of IMT are not available. Therefore we investigated the whole-body distribution of IMT in six patients with cerebral gliomas and the radiation doses were estimated. Whole-body scans were acquired at 1.5, 3 and 5 h after i.v. injection of 370–550 MBq IMT. The bladder was voided prior to each scan and the radioactivity excreted in the urine was measured. Based on the MIRD-11 method and the updated MIRDOSE3, the mean absorbed doses for various organs and the effective dose were calculated from geometric means of the anterior and posterior whole-body scans using seven source organs and the residence time. IMT was predominantly excreted by the kidneys (52.8%±11.5% at 1.5 h p.i., 63.0%±15.7% at 3 h p.i. and 74.6%±9.8% at 5 h p.i.). No organ system other than the urinary tract showed significant retention of the tracer. Early whole-body scans revealed slightly increased tracer uptake in the liver and in the bowel. Highest absorbed doses were found for the urinary bladder wall (0.047 mGy/MBq), the kidneys (0.010 mGy/MBq), the lower large intestinal wall (0.011 mGy/MBq) and the upper large intestinal wall (0.008 mGy/MBq). The effective dose according to ICRP 60 was estimated to be 0.0073 mSv/MBq for adults. This leads to an effective dose of 3.65 mSv in a typical brain SPET study using 500 MBq IMT. The MIRDOSE3 scheme yielded similar results. Thus, in spite of the relatively high tracer dose required for optimal brain scanning, radiation exposure in SPET studies with IMT is in the normal range of routine nuclear medicine investigations.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-2451
    Keywords: Follicular thyroid carcinoma ; Morphology ; Prognosis ; DNA-cytophotometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung In einer retrospektiven Studie an 95 folliculären Schilddrüsencarcinomen wurden verschiedene morphologische und klinisch-biologische Parameter auf ihre prognostische Bedeutung geprüft. Das klinische Verhalten der Tumoren wurde vorrangig durch Vorhandensein oder Fehlen einer Kapselbegrenzung bestimmt: Grob invasive Carcinome zeigten sechsfach häufiger einen letalen Verlauf als gekapselte Neoplasien. Ein ungünstigeres Verhalten ergab sich ferner bei Manifestation des Tumors im höheren Lebensalter (Schwellenalter: 52 Jahre) und bei Nachweis einer oxyphilen Differenzierung, weiterhin bei Vorliegen von Lymphknotenmetastasen, einer Halsweichteilinfiltration und - im Fall gekapselter Carcinome - von Fernmetastasen. Dagegen hatten die Faktoren Differenzierungsgrad und Geschlecht keinen signifikanten Einfluß auf die Prognose. Bei 22 Tumoren erfolgten cytophotometrische und flußcytometrische DNS-Bestimmungen. Der diagnostische Nutzen dieser Verfahren war dadurch limitiert, daß an Hand der DNSHistogramme in der Mehrzahl der Carcinome keine eindeutige Dignitätsbeurteilung getroffen werden konnte. Dagegen erwiesen sie sich als brauchbares Instrument für die Prognosebeurteilung individueller grob invasiver Tumoren. Die diagnostische, differentialtherapeutische und prognostische Bedeutung der Befunde sowie deren Relevanz für die Subklassifikation folliculärer Schilddrüsencarcinome wird diskutiert.
    Notes: Summary A retrospective study of 95 follicular thyroid carcinomas was conducted to evaluate the prognostic value of different morphological and clinical features. The biological behaviour of these tumours was primarily influenced by presence or absence of a capsule type of confinement: the frequency of lethal outcome among widely invasive carcinomas was six times higher than among encapsulated neoplasms. Furthermore, dismal prognosis could be demonstrated for tumours occurring in older patients (with a sharp break in the prognosis at the age of 52 years) and for those lesions which displayed oxyphilic metaplasia. The same effect was shown for presence of lymph node metastasis, tumour invasion of the cervical soft tissue and, for the case of encapsulated carcinomas, distant haematogenous spread. Conversely, the degree of differentiation and the patients' sex proved to have no significant influence on prognosis. In 22 carcinomas, cytophotometric and flow-cytometric determinations of DNA values were performed. These procedures revealed to have only limited diagnostic value, since for the majority of the tumours, benignancy or malignancy could not be judged from the DNA histograms. However, DNA measurements proved to contribute valuable information for the prognosis in individual cases of widely invasive follicular carcinomas. The discussion focuses on the diagnostic, therapeutic and prognostic relevance of these findings and on their impact on subclassification of follicular thyroid carcinomas.
    Type of Medium: Electronic Resource
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