A possible role for somatostatin receptor scintigraphy in the diagnosis and follow-up of children with medulloblastoma.

The surgical resection of medulloblastoma (MB), the most frequent malignant brain tumor in children, often remains subtotal. To estimate the response to further treatment the residual tumor is monitored by CT or MRI. The interpretation of both imaging techniques is complicated by disturbances resulting from surgery and radiation. Our study searched for alternative imaging techniques and asked the following questions. 1) Do MB express somatostatin receptors (SSTR), 2) is SSTR scintigraphy a sensitive imaging technique for the follow-up and the detection of vital tumor tissue in children with MB, and 3) do the results of SSTR scintigraphy correlate with the in vitro analysis of MB tissue by SSTR autoradiography. We analyzed the SSTR status in 20 children with MB, aged 1 to 15 years. Sixteen SSTR scintigraphies using Indium-111-DTPA-D-Phel-pentetreotide were performed in 14 children. MB tissue of 14 children was analyzed by SSTR autoradiography using Iodine-125-Tyr3-octreotide. In 8 cases SSTR were measured by both methods in vivo and in vitro. In comparison with conventional imaging, results of SSTR scintigraphy were true positive in 7 of 7 patients, true negative in 9 of 9 patients, including one patient with false positive findings in MRI, false negative in only one patient with small spinal metastases (diameter < 3 mm) and false positive in none of the analyzed patients. In all cases with residual tumor (n = 3) and suspected relapse (n = 4) the diagnosis could be confirmed (n = 4) or excluded (n = 3), consistent with the results of MRI and tumor histology. All MB tissues analyzed by SSTR autoradiography (n = 14) showed an extremely high density of SSTR ranging from 4047 to 15526 dpm/mg MB tissue. MB (n = 8) which were analyzed by SSTR scintigraphy and autoradiography demonstrated consistent results in evaluation by both methods. In cases where the integrity of the blood-brain barrier was tested by Tc-99m-DTPA scintigraphy (n = 10), the SSTR-to-brain scintigraphy index confirmed the tumor specificity of radionuclide uptake. We conclude that 1) MB tissue expresses a particularly high density of SSTR, 2) the high density of SSTR in autoradiography correlates with a sensitive imaging of these tumors by SSTR scintigraphy, 3) SSTR scintigraphy might be a valuable imaging method for detection of vital MB tissue in patients with residual tumor or relapse.

Effect of specific activity on cardiac uptake of iodine-123-MIBG.

UNLABELLED: Radioiodinated meta-iodobenzylguanidine (MIBG), an analog of norepinephrine, has been used to assess myocardial sympathetic innervation. Recent in vivo studies predict enhanced cardiac uptake of this radiopharmaceutical with high specific activity. METHODS: To clarify the effect of specific activity on cardiac uptake of radioiodinated MIBG, the distribution and kinetics of no-carrier-added [123I]MIBG (> or = 7.4 TBq/mumol) were compared with those of commercial [123I]MIBG (approximately 74 MBq/mumol) in three healthy volunteers by serial imaging and blood sampling. RESULTS: Higher specific activity result in higher uptake of radioiodinated MIBG in all volunteers in the heart (p < 0.05) and liver (p < 0.05) but not in the lung (p = 0.26). Due to rapid deiodination, a more pronounced accumulation of radioactivity was present in plasma after no-carrier-added MIBG than commercial [123I]MIBG, resulting in higher background and thyroid activity after administration of the former. Calculated heart-to-liver (p = 0.96) and heart-to-lung (p = 0.42) count ratios in all volunteers revealed no significant improvement in cardiac imaging with no-carrier-added [123I]MIBG compared to commercial [123I]MIBG. CONCLUSION: This study highlights the appreciably higher in vivo deiodination of no-carrier-added [123I]MIBG compared to commercial preparation of [123I]MIBG in humans. Cardiac images acquired with no-carrier-added [123I]MIBG do not seem to be superior to those obtained with commercial MIBG.

Comparison of transcranial sonography, magnetic resonance imaging, and single photon emission computed tomography findings in idiopathic spasmodic torticollis.

Various lines of evidence suggest that the basal ganglia and thalamus are involved in the pathogenesis of idiopathic dystonia, but unfortunately neuroradiological and pathological data are sparse and controversial. In this study, we have examined 10 patients with spasmodic torticollis by neuroimaging techniques, including transcranial sonography (TS; n = 10), conventional (n = 10) and diffusion-weighted (n = 5) magnetic resonance imaging (MRI), and single photon emission computed tomography (SPECT; n = 10), employing [123I]iodobenzamide (IBZM) as a ligand with a high affinity to the D2 receptor. In seven patients, TS showed small hyperechogenic lesions in the medial segments of the lentiform nucleus contralateral to the side of head deviation. In accordance with the site of TS abnormalities, diffusion-weighted MRI displayed a hyperintense lesion in only one patient, while standard MRI of this area was normal in all patients. SPECT revealed a slight but statistically nonsignificant reduction of IBZM tracer uptake in an area corresponding to the dorsal portions of the striatum in 9 of the 10 patients. TS findings support the hypothesis that structural alternations of the pallidothalamic circuit contralateral to the side of head deviation are involved in the pathogenesis of idiopathic spasmodic torticollis. TS may be more sensitive in detecting basal ganglia alterations than MRI.

A comparison of qEEG and HMPAO-SPECT in relation to the clinical severity of Alzheimer's disease.

Electroencephalographical studies have disclosed correlations between topographical features of Fast Fourier Transformation maps and the severity of Alzheimer's disease (DAT). The object of the present study was to explore the relations of HMPAO-SPECT and quantitative EEG (qEEG) with the severity of dementia. Twenty-three patients were included in the study. Spectral and topographical EEG parameters were compared with global and regional cerebral blood flow, and with psychometric measures of clinical severity. None of the regions of interest of the SPECT scans were significantly correlated with clinical severity. Low values in delta- and theta bands, however, were related to high scores on the Mini-Mental-State examination (P < 0.01), whereas the Syndrome-Kurz test correlated inversely with the power values in the alpha and beta band. The global decrease in cerebral blood flow (CBF) was associated with a shift on the topographical alpha-centroids in the posterior direction (P < 0.01). In previous studies correlations between CBF and clinical severity were weak, indicating a high interindividual variance, or interactions with concomitant vascular lesions. Whereas SPECT is a well-established tool for the diagnosis of dementia, the present study indicates qEEG as a potential marker for the staging of the cognitive decline in DAT.

Effect of specific activity on organ uptake of iodine-123-meta-iodobenzylguanidine in humans.

Radioiodinated meta-iodobenzylguanidine (MIBG), an analogue of norepinephrine, has been used in management of neuroendocrine tumors. Recent studies reveal that distribution of radioiodinated MIBG in animals depends on the specific activity of this radiopharmaceutical. In order to clarify the effect of specific activity on organ uptake of radioiodinated MIBG. the kinetics of no-carrier-added (n.c.a.) [I-123]MIBG (greater than or equal to 7.4 TBq/mu mol) were compared with those of commercial (com.) [I-123]MIBG (similar to 74 MBq/mu mol) in 3 healthy volunteers by serial imaging and blood sampling. The organ uptake of radioiodinated MIBG did not remarkably differ between the two specific activities. Due to rapid degradation a more pronounced accumulation of radioactivity was present in plasma alter n.c.a. than after com. [I-123]MIBG resulting in a higher background and thyroid activity. In addition due to a prolonged residence time of the radioactivity, the radiation exposure to organs was in general slightly higher with n.c.a. [I-123]MIBG as compared to com. [I-123]MIBG. This finding highlights the higher in vivo deiodination of n.c.a. [I-123]MIBG than of com. [I-123]MIBG in humans. In the treatment of children suffering from neuroblastoma, therefore, degradation of n.c.a. [I-123]MIBG may decrease the concentration of radioiodinated MIBG available for binding at tumor sites and result in higher radiation exposure of non-tumor tissue.

Improved determination of variant erythrocytes at the glycophorin A (GPA) locus and variant frequency in patients treated with radioiodine for thyroid cancer.

Red blood cells from individuals with the blood group MN express each form of the allelic GPA protein (GPAM and GPAN) on their cell surface. Variant cells have lost one form of the protein. Their frequency is about 10(-5) in blood from unexposed persons. The BR6 assay is currently the most widely used assay to determine variant frequency (VF) by immunolabelling and flow cytometry. The precision of the BR6 assay is mainly limited by the Poisson error because only small numbers of variant cells are detected in each assay. The BR6 assay has been improved by magnetic cell separation (MACS) of variant erythrocytes prior to their determination by this assay. This new version of the assay is named 'MACS-BR6'. It allows enumeration of variant cells from 2 x 10(8) or more blood cells instead of 5 x 10(6) in the BR6 assay with a precision which is about 5 times higher than that of the BR6 assay. The MACS-BR6 assay was used to determine the VF of GPAN/0 and GPAN/N variant cells in 12 healthy adults and 11 patients treated with radioiodine for thyroid cancer 2 to 16 years before. The average red bone marrow dose was 347 mGy. In healthy adults the mean VF of GPAN/0 and GPAN/N variant cells was 16.1 x 10(6) and 5.3 x 10(-6) respectively. In patients the corresponding mean VF was 25.4 x 10(6) and 11.9 x 10(-6), respectively. The patients GPAN/0 VF was significantly higher than that of controls. In patients VF increases linearly with the dose. The linear regression parameters of VF were 16.6 x 10(-6) (intercept), 23.7 x 10(-6) GY-1 (slope) and 6.3 x 10(-6) (intercept), 12.9 x 10(-6) Gy-1 (slope) for GPAN/0 and GPAN/N variant cells, respectively.

Left hemispheric reductions of regional cerebral blood flow (rCBF) correlate with measures of dementia severity in patients with Alzheimer's disease: a SPECT study.

Regional cerebral blood flow (rCBF) values were measured by single photon emission computed tomography (SPECT) in different regions of the brain in 27 patients with DAT. Significant correlations were found between rCBF in left parieto-temporooccipital regions and psychometric test scores. Patients with hemisphere asymmetry in SPECT performed worse on psychometric tests. SPECT did not permit prediction of or differentiation between depressive and psychotic symptoms.

[Significance of 2 different bone density measurement methods in the assessment of mineral content of the peripheral and axial skeleton]. / Stellenwert zweier unterschiedlicher Knochendichtemessmethoden zur Bestimmung des Mineralgehalts am peripheren und axialen Skelett.

Between May 1990 and February 1991 we enrolled 212 patients of 410 referred to our clinic for bone mass evaluation according to different diagnosis or therapeutic procedures. These patients were divided into 7 groups. The question had to be answered, which method of measurement and which skeletal site would give better information about the influence of the diseases of therapeutic procedures. We measured the areal mineral density of the lumbar spine with dual x-ray absorptiometry (DEXA) and the mineral content of the total and trabecular bone mass of a cross-sectional slice at the distal radius with peripheral quantitative computed tomography (pQCT). The results were statistically analysed. We calculated the percentage deviation from young normals. Trabecular mineral content showed the greatest difference (18% to 44%), compared to the healthy reference group, corresponding to the known higher turnover of this bone compartment. In contrast, the difference of the areal density of the lumbar spine was found to be lowest (4% to 27%). In order to compare the methods objectively, we additionally calculated a ROC-analysis of two postmenopausal groups (51 healthy, 46 osteoporotic) to demonstrate the diagnostic validity. The validity proved to be substantially better when purely trabecular bone at the distal radius was measured. The ROC-curves showed a sensitivity of 84% for radial trabecular bone on a specificity level of 90%, whereas the lumbar spine values presented with a sensitivity of only 68%.

Histochemical localization and quantification of glucose-6-phosphate dehydrogenase in bovine leydig cells.

Some of the critical steps in the qualitative histochemical localization of glucose-6-phosphate dehydrogenase (freezing procedures, incubation techniques and the influence of intermediate electron carriers, respiratory chain inhibitors and different tetrazolium salts) were evaluated in sections of bovine testis as a prerequisite for the microdensitometric estimation of the activity of the enzyme in bovine Leydig cells in situ. A modification of the gel incubation method of Rieder et al. (1978) gave the best results and was used for the quantitative investigations. Quantitative data for the dehydrogenase activity gained from microdensitometry of the formazan final reaction products in Leydig cells in situ were compared with the results of assays of the activity in homogenates of testis. The following apparent kinetic properties of glucose-6-phosphate dehydrogenase were obtained for the enzyme in Leydig cells in situ: Vmax = 0.11 absorbance units/min, Km = 0.37 mM. The quantitative characterization of glucose-6-phosphate activity in Leydig cells in situ appears to be suitable for combined morphological and functional diagnoses of small tissue samples such as testicular biopsies. This would give valuable information of the functional status of Leydig cells in normal and diseased testicular tissue.