Direct radiation exposure of the eye lenses in cranial computed tomography and exposure reduction through radiographer training.

INTRODUCTION: Ionizing radiation can cause increased opacity of the lens and later lead to radiation-induced cataract. Therefore, the eye lens should be positioned outside of the direct radiation beam in cranial computed tomography (CCT). If this is not possible, protective measures must be taken, which includes the use of external lens protectors. In this study we assess whether direct radiation exposure of the eyes in CCT can be reduced by trained radiographers and whether the use of eye lens protectors improves after training. METHODS: First, we evaluated 763 non-enhanced CCT regarding direct radiation exposure of eyeballs and eye lenses and usage of lens shielding. Afterwards, we trained radiographers to avoid radiation exposure of the eyes by head adjustment and protectors and assessed the improvements in a subsequent study of 678 CCT. We tried to identify factors that influenced radiation exposure of the eye lens. RESULTS: After training, frequency of radiation exposure of lenses was significantly reduced by 5.9% (220/763 patients in pre- vs. 155/678 patients in post-training group, p = 0.01). The use of external lens protectors significantly increased after training by 9.8% (37/763 patients in pre- vs. 99/678 patients in post-training group, p < 0.001). The absence of tiltable headrest was a risk factor for increased eye lens radiation exposure in the pre-training group. The presence of cervical spine immobilizer was associated with more frequent radiation exposure of the lenses in the pre- and post-training group. CONCLUSIONS: Radiographer training and the use of tiltable headrest lead to reduction of radiation exposure to the eye lens. IMPLICATIONS FOR PRACTICE: Radiographer training is an effective method to reduce eye lens exposure in CCT. The usage of tiltable headrest minimizes the radiation exposure of the lenses.

Measuring Ventricular Width on Cranial Computed Tomography: Feasibility of Dose Reduction in a Custom-Made Adult Phantom.

PURPOSE: To estimate feasible dose reduction to reliably measure ventricular width in adults with hydrocephalus in follow-up cranial computed tomography (CCT) using a custom-made phantom. MATERIALS AND METHODS: A gelatine-filled adult calvarium with embedded central fibers of two carrots representing the lateral ventricles was used as a phantom. The phantom was scanned 11 times with two CT scanners (LightSpeed Ultra, GE and Somatom Sensation, Siemens), using tube currents of 380/400, 350, 300, 250, 200, 150 and 100 mA, and tube voltages of 140, 120, 100 and 80 kV. The width of the carrots was measured at four sites in consensus decision of two principle investigators blinded to the scan parameters. Values measured at 380/400 mA and 140 kV served as a reference for the width of the ventricles. Measurements received 1 point if they did not differ more than 0.5 mm from the reference values. A maximum score of 4 could be achieved. RESULTS: The relationship between the correct width measurement of the carrots (lateral ventricles) and the radiation dose can be described by a quadratic regression function. Pixel noise increases and accuracy of measurements decreases with a lower radiation dose. Starting from a tube current of 380/400 mA and a tube voltage of 140 kV, the dose can be reduced by 76 % for LightSpeed Ultra and by 80 % for Somatom Sensation provided that a margin of error of 37.5 % (score = 2.5) for correct width measurement of the carrots is accepted. CONCLUSION: Lowering the radiation dose by up to 48 % for LightSpeed Ultra and by 52 % for Somatom Sensation, compared to the standard protocol (120 kV and 400 mA) still allowed reliable measurements of ventricular widths in this model. KEY POINTS: • There is a quadratic relationship between correct width measurements of lateral ventricles and radiation dose in CT. • Reduction of radiation dose results in increased pixel noise and increased error for correct ventricle width measurement. • Due to a considerable attenuation difference between cerebrospinal fluid and brain parenchyma, a dose reduction for the determination of ventricular size in CT seems feasible and should be performed.

[Diagnosis and differential diagnosis of Graves' orbitopathy in MRI]. / Diagnose und Differenzialdiagnose der endokrinen Orbitopathie in der MRT.

Imaging of Graves' orbitopathy (GO) includes radiological and nuclear medicine procedures. Depending on the method used they provide information about the distribution and activity of the disease. Magnetic resonance imaging (MRI) is not only a helpful tool for making the diagnosis it also enables differentiation of the active and inactive forms of GO due to intramuscular edema. The modality is therefore appropriate to evaluate the disease activity and the course of therapy. The disease leads to the typical enlargement of the muscle bodies of the extraocular muscles. The inferior rectus, medial rectus and levator palpebrae muscles are mostly involved. Signal changes of the intraconal and extraconal fat tissue are possible and a bilateral manifestation is common. The differential diagnosis includes inflammatory diseases and tumors, of which orbital pseudotumor (idiopathic, unspecific orbital inflammation), ocular myositis and orbital lymphoma are the most important. The specific patterns (localization, involvement of orbital structures and signal changes) can be differentiated by MRI.

[Long-term results of iridocyclectomy for iris tumours]. / Langzeitergebnisse nach Iridozyklektomie bei Iristumoren.

BACKGROUND: The aim of this study was to evaluate the long-term survival rate and functional results after iridocyclectomy. PATIENTS AND METHOD: Between 1980 and 2002 39 patients (26 female and 13 male) ranging in age from 20 to 79 years (median m = 58 years) underwent iridocyclectomy for a tumour of periphery iris by means of a lamellar technique or by trepanating. Follow-up time ranged from 3 months to 24 years (m = 11.2 years). RESULTS: In 21 cases (54 %) there was a malignant tumour including 20 melanomas (mostly spindle-cell and mixed-cell melanomas) and one filiae of a bronchial carcinoma. There was a variety of histopathological entities in the 18 benign lesions (46 %). Naevi were the most frequent. The outcome was satisfactory: 57 % of the patients kept a visual acuity of > 0.5. Three eyes had to be enucleated. The rate of recurrence was 10 % (4 cases). The Kaplan-Meyer estimate for the 10-year-survival of the patients with a malignant iris tumour was 77 %. Two patients died of metastic melanoma following spindle-cell and mixed-cell melanoma. CONCLUSION: The long-term functional results after Iridocyclectomy are good, whereas complications and recurrences are rare. The 10-year-survival is high. Over a long period iridocyclectomy is a recommendable surgical procedure for removal of progredient tumours of the anterior uvea.

Prosthetic valve endocarditis: importance of surgical treatment.

Surgical therapy of prosthetic valve endocarditis (PVE) is still associated with a high mortality of up to 80 %. Further risk analysis and characterization of clinical features are important for a further improvement of surgical results. The aim of this retrospective study was a risk analysis of clinical features of the pre-, intra-, and postoperative period. Between February 1998 and December 2004, 70 patients (52 male, 18 female, age 62 +/- 11 years) were referred to our institution for surgical therapy of PVE. This cohort included 16 patients with early PVE and 54 patients with late PVE. Preoperative, intraoperative and postoperative features were evaluated with respect to their influence on the early postoperative course and the midterm follow-up. The aortic valve was affected in 41 patients (58.6 %) and the mitral valve in 15 patients (21.4 %). Double valve infection was recorded in 14 patients (20.0 %). Staphylococci (n = 36, 51.4 %), Streptococci (n = 9, 12.9 %) and others (n = 24, 14.5 %) were identified as causative agents in blood cultures. The hospital mortality rate was 20.0 % (n = 14), during follow-up (mean follow up: 3.3 +/- 2.5 years), a further 11 patients (15.7 %) died, resulting in an overall mortality of 35.7 %. The main predictors for hospital mortality were preoperative heart failure ( P = 0.01) and Staphylococci infection ( P = 0.01). Predictors of overall mortality were Staphylococci infection ( P = 0.01), heart failure ( P = 0.02) and abscess formation ( P = 0.02). Surgical therapy of prosthetic valve endocarditis is still associated with quite a high mortality during the early and midterm follow-up. Predictors of outcome particularly include preoperative risk constellations (heart failure, Staphylococci infection).

Establishment and characterization of an EBNA-negative human lymphoma cell line (BHL-89).

BACKGROUND: The aim of the work was to establish human malignant lymphomas in culture, in order to study the biological characteristics and drug sensitivity of lymphomas of human lymphoid origin. MATERIALS AND METHODS: Lymph nodes of patients were explanted and kept in cultures using conventional tissue culture methods. Cytogenetic methods were used for karyotype analysis. Clonogenic assay was applied to test drug sensitivity. The tumorigenic capacity of the cells was determined by inoculating them into immunosuppressed mice. Immunological and other markers were examined with conventional techniques. RESULTS: A cell line, BHL-89, was established in culture from a patient with B-cell type non-Hodgkin's malignant lymphoma. Cells started to grow after a few days without a feeder layer in stationary suspension. The population doubling time was 48 h. The cells were hyperploid, and non-random aberrations were +1, -15, +14q+. Cloning efficiency in soft agar was found to be as high as 50-60%. The cells expressed markers characteristic of early B cells. The BHL-89 cells were Epstein-Barr nuclear antigen (EBNA) negative. They produced tumors when 10(7) cells were injected into immunosuppressed mice. The cells were sensitive to dibromodulcitol (Elobromol), an alkylating antitumor drug, and resistant to the phorbol ester TPA. CONCLUSIONS: The established EBNA-negative BHL-89 cell line has a few unique characteristics, e.g. rapid establishment without feeder cells, origin from the lymph node of an adult patient, high clonogenicity in soft agar, and resistance to TPA. The cell line is suitable for studying the nature of B lymphomas and testing compounds against lymphoproliferative disorders.

Antitumour effect of a gonadotropin-releasing-hormone antagonist (MI-1544) and its conjugate on human breast cancer cells and their xenografts.

Our gonadotropin-releasing hormone (GnRH) antagonist analogue MI-1544 ([Ac-D-Trp1,3,D-Cpa2,D-Lys6,D-Ala10]GnRH) was developed as a potential contraceptive material, because it decreased the luteinizing hormone level without unfavourable side-effects. The antagonist was covalently bound to poly[Lys-(Ac-Glu0.96-DL-Ala3.1)] (AcEAK)-a branched polypeptide having a polylysine backbone--resulting in a MI-1544-AcEAK conjugate. According to our in vitro experiments the MI-1544 induced a 33%-35% decrease in cell numbers of MCF-7 and MDA-MB-231 human breast cancer cell lines at a dose of 30 microM. The biodegradable polymeric carrier, AcEAK, alone inhibited cell proliferation by only 13%-15%, while the MI-1544-AcEAK conjugate, applied at the same dose, was capable of producing 45%-50% inhibition of cell proliferation. Our in vivo experiments using immunosuppressed mice showed that MI-1544, applied twice daily s.c., inhibited the growth of oestrogensensitive and -insensitive xenografts by 65% and 30% respectively. This effect was potentiated (70%) in both types of xenografts by the presence of the polymeric carrier in the conjugate; however, the carrier by itself did not cause tumour growth inhibition. The polymeric polypeptide carrier is supposed to increase the stability of the GnRH antagonist and to prevent the rapid excretion of the covalently bound peptide molecule. The antagonist and its conjugate may have various direct and indirect effects on breast cancer cells and, as a consequence, the new GnRH antagonist conjugates are suitable for treating an extended range of breast cancers.

Establishment, characterization and drug sensitivity of a new anaplastic thyroid carcinoma cell line (BHT-101).

A thyroid carcinoma cell line, BHT-101, has been established in vitro from a metastatic lymph node deposit in a female patient with a non-hormone producing anaplastic, partly thyroglobulin- and thyroxine (T4)-positive papillary thyroid cancer. The cell population is heterogeneous, containing epithelial-like and fibroblast-like cells, and has a doubling time of 24 h. The cell line is polyploid with hypertetraploid predominance and the karyotype showed trisomies, tetrasomies, pentasomies as well as many marker chromosomes. The majority of the cells are negative or weakly positive for thyroglobulin and thyroxine and estrogen and progesterone receptors are present in the cells. BHT-101 cells produce tumours when injected into immunosuppressed CBA/Ca mice. The cells are sensitive to adriamycin, methotrexate and tamoxifen but not to methimazole (Favistan). The epithelial-like clone 1 and the fibroblast-like clone 3, isolated from the parental line, differed in drug sensitivity. This new cell line is suitable for studying the biology of thyroid carcinoma and for parallel in vivo and in vitro studies of drug activity against thyroid cancer.

Comparative studies on the polyamine metabolism and DFMO treatment of MCF-7 and MDA-MB-231 breast cancer cell lines and xenografts.

In order to characterize the estrogen receptor (ER)-positive MCF-7 and ER-negative MDA-MB-231 human breast cancer cells and xenografts, their growth kinetic parameters and some biochemical characteristics concerning the receptor status and polyamine metabolism were determined and compared. The doubling times calculated from the growth curves showed higher proliferation rate of MDA-MB-231 cells, both in culture (21 hours) and in xenograft (9.7 days), in comparison to the MCF-7 cells which had values of 32 hours and 11.6 days, respectively. Growth-dependent changes observed in the intracellular putrescine, spermidine and spermine concentrations indicated a higher activity of polyamine metabolism in the MDA-MB-231 cells and xenograft as well. However, biosynthetic key-enzyme ornithine decarboxylase activity (ODC, EC 4.1.1.17) showed neither characteristic differences between the two types of breast cancer, nor consistent relationship with their proliferation rate. Metabolic alterations of the MCF-7 and MDA-MB-231 cell lines grown in vitro were also reflected in the polyamine composition of their culture medium. Independently of their receptor status, both types of breast cancer were responsive to difluoromethylornithine (DFMO) treatment. DFMO inhibited the ODC activity totally and depleted the cellular polyamine levels. MCF-7 cells in culture were more sensitive to the antitumoral effect of DFMO than the MDA-MB-231 line, while the rate of growth inhibition did not differ significantly in the xenografts. The present results provided further evidence on the different polyamine metabolism of ER-positive MCF-7 and ER-negative MDA-MB-231 human breast cancer cells in vitro and in vivo, suggesting a correlation of hormonal modulation with polyamines as a determinant group of biological response modifiers.

Influence of luteinizing hormone-releasing hormone agonists on human mammary carcinoma cell lines and their xenografts.

The specific binding of luteinizing hormone-releasing hormone (LH-RH) agonist in estradiol-dependent MCF-7 and estradiol-independent MDA-MB-231 human breast cancer cells has been studied using [3H]Ovurelin [(D-3H-Phe6),des-Gly10-LH-RH- ethylamide]. The results of Scatchard analyses suggest the presence of a single class of receptor sites, both in cell suspensions and membrane fractions. Evaluation of these peptide receptors appears to reflect additional characteristics of biological behaviour of these human breast cancer cells. The synthetic LH-RH agonist Ovurelin [(D-Phe6),des-Gly10-LH-RH-ethylamide] can directly interfere (25-30%) with the proliferation of MDA-MB-231 human breast cancer cells in culture. The inhibitory effect of Ovurelin in vitro was negligible in the MCF-7 cell line. In the in vivo experiments the treated immunosuppressed mice bearing either MCF-7 or MDA-MB-231 xenografts responded to the high-dose LH-RH analogue Zoladex depot and Decapeptyl depot therapy. Since the MDA-MB-231 tumour was found to be ER-negative it seems possible that the regression of this xenograft results from the direct antitumor action of the LH-RH agonist.