Biochemical markers of bone turnover in patients with thyroid dysfunctions and in euthyroid controls: a cross-sectional study.

Hyperthyroidism is associated with reduced bone mineral density. Conflicting data exist regarding the effects of thyroxine therapy on bone metabolism. The aim of the present study was to assess changes in markers of bone turnover in thyroid dysfunction. A total of 28 patients with overt hyperthyroidism, eight patients with suppressed TSH levels (thyroid hormones within the euthyroid range, no T4 therapy), 25 euthyroid and four hypothyroid patients were included in the present study. Hyperthyroidism resulted in increased bone metabolism, as reflected by increased bone resorption and bone formation parameters. No significant differences in mean levels between patients with TSH supression and those with euthyroidism could be observed; however, a higher frequency of elevated urinary PYD- and DPD excretion rates were noted in patients with TSH suppression. Regression analysis revealed highly significant correlations between bone resorption markers and thyroid parameters, suggesting, that even a mild thyroid hormone excess may lead to an increase in bone resorption. In subjects with suppressed TSH levels and peripheral thyroid hormone levels within the euthyroid range, elevated bone resorption markers point to subclinical hyperthyroidism, if other reasons for an increase in bone turnover rates can be excluded.

Neuroimaging findings in a patient recovering from global alexia to spelling dyslexia.

The authors report findings in a 67-year-old right-handed man who had an ischemic infarct in the territory of the left posterior cerebral artery. The clinical manifestation consisted mainly of total alexia without agraphia. The patient gradually recovered, subsequently showing the syndrome of spelling dyslexia. Cerebral MR-images revealed a circumscript infarction of medial and basal parts of left temporal lobe. In the acute stage [99mTc]HM-PAO SPECT was characterized by a diminished uptake in the definitely infarcted area and hyperfixation in the region of the left forceps major. Because high retention of HM-PAO indicates potentially salvageable tissue after an ischemic event, the depicted area might be correlated with the recovery of function. Thus, the authors' neuroimaging data give further support to the assumption that the left forceps major is a critical area for global alexia, whereas spelling dyslexia is due to involvement of the left medio-basal temporal lobe.

Partial epileptic seizure with versive movements examined by [99m Tc] HM-PAO brain single photon emission computed tomography: an early post study analyzed by computerized brain atlas methods.

The consecutive steps of a seizure with leftward versive movements of the head and eyes were analyzed after video monitoring and correlated with findings on single photon emission computed tomography (SPECT) using [99m Tc] hexamethyl propylene amine oxime (HM-PAO). Evaluation included reconstruction of subtraction images from the early postictal state, obtained immediately after the video-monitored seizure, and the interictal baseline. Based on normalized perfusion indexes within voxels of Talairach space, we concluded that the primary epileptogenic focus was in the premotor cortex of the contralateral hemisphere. We then placed the functional data in an anatomic context by adapting a dedicated computerized brain atlas (CBA) to the patient's brain with the aid of magnetic resonance imaging (MRI) slices. By inverse transformation, the patient's data were aligned with the standard geometry of the brain atlas for comparison purposes with data from the literature. The validated activation field projected exactly onto the right precentral sulcus with the anterior border zone including the right frontal eye field.

[Surgical and nuclear medicine treatment of hyperthyroidism]. / Chirurgische und nuklearmedizinische Behandlung der Hyperthyreose.

Radioiodine and surgery are the therapeutic tools of choice for the definitive treatment of patients suffering from hyperthyroidism. The decision on the therapy to choose for an individual patient will depend on several different factors: etiology of the hyperthyroidism, size of the goiter, age and general medical considerations, availability of radioiodine therapy or of an experienced endocrine surgeon, and the patient's own preferences. It is important for the general practitioner attending and advising a patient to have a basic knowledge of both therapeutic modalities. An overview of indications, results and risks of the radioiodine and surgical therapy is presented.

Single photon emission computed tomography with 99mTc hexamethyl propylene amine oxime (HMPAO) and focal motor seizures.

The proper localization of regions of interest (ROIs) in Single Photon Emission Computed Tomography (SPECT) is an essential task. The limited spatial resolution makes it difficult to define regions by their structure. The particular problems are: 1) the difficulty to find the appropriate slice and its orientation in space; 2) the individual variation of the brain in dimension and shape. Referring to the basic work of Talairach and Szikla (1967), research is conducted to overcome these methodical problems in interpreting cranial computed tomography by using a proportional localization system. We analyzed four cases with focal motor seizures of different aetiology (tumour, hemorrhagic infarction, intracerebral hematoma, multifocal leukencephalopathy) by 99mTc HMPAO SPECT. The accumulation of the radiopharmacon was measured in ROIs which were delineated with the aid of the above mentioned system. The regions were selected in accordance to the autoradiographic study of penicillin induced epileptic seizures in animal experiments. Dependent on the severity of the clinical manifestation we were able to document the involvement of the supposed primary focus and of several related zones. We suggest that this approach should prove some usefulness in the examination of the interdependency of different brain areas.

In vitro and in vivo testing of the dopamine D1 ligand [123I]SCH 23982 with respect to its potential application in SPET investigations.

[123I]SCH 23982, a dopamine D1 ligand, was labelled in a large scale process and then tested in vitro for binding to rat brain sections and membranes. Because of the promising values of KD = 1.5 x 10(-10) M and Bmax = 0.7 x 10(-11) mol/g, in vivo evaluation was performed on rats and normal volunteers to test its possible usefulness for SPET imaging. In competition experiments, a higher binding in the presence of sulpiride was found while ketanserin displaced [123I]SCH 23982 only at a 10,000-fold excess. Differences between rats and men were seen with respect to their metabolism. SPET investigations failed because the washout of [123I]SCH 23982 was too rapid.

Evaluation of a multicentre study with Iomazenil--a benzodiazepine receptor ligand.

After showing in an earlier publication that Iomazenil is a potent benzodiazepine receptor antagonist, the substance has been distributed to 11 clinical centres in Europe for further tests. The protocol asked for volunteers, epileptic cases and patients with Alzheimer's disease. Prior to the Iomazenil examination, flow images by perfusamine or HMPAO were required, and as comparative methods EEG, computed tomography (CT) and magnetic resonance imaging (MRI) were performed. The results allowed first the determination of the normal distribution of the benzodiazepine receptors in the human brain. The highest uptake was found in medial occipital cortex. Second, the evaluation of the epileptic cases shows a 100% positive prediction value for Iomazenil compared to 92% for flow images. Negative prediction values were calculated as 81% for Iomazenil and 54% for flow images. Furthermore, one group reported the successful diagnosis of Alzheimer's disease at an early stage. The visual image examination was tentatively compared to a more objective semiquantitative one based on quotients of corresponding left/right regions of interest. This semiquantitative method has not proved successful yet, but the problems have been identified. A more precise protocol for further studies is therefore proposed.

[The contribution of single-photon emission-computed tomography in cerebral function diagnosis]. / Der Beitrag der Single-Photon-Emissionscomputertomographie zur zerebralen Funktionsdiagnostik.

Single photon emission computed tomography (SPECT) makes it possible to visualize physiological and chemical processes in the cerebrum. In this technique, single photon emitting nuclides such as 99m technetium and 123 iodine, which are tagged to other compounds, or 133xenon, are used for the study of several clinical conditions. After injection of the radiopharmaceutic agent the radioactivity is measured by a rotating gamma-camera from numerous directions. Based on the measured values, its distribution within the brain can be computed and transformed in tomographic slices. We present our experience with the method in clinical practice using preferentially N-isopropyl-(123I)-p-iodoamphetamine (123I-IMP) and 99mTc hydroxymethyl-propylene-amine-oxime (99mTc-HMPAO). These substances are distributed in accordance with regional cerebral blood flow (rCBF). Hitherto, the application of the method has concentrated on the study of cerebrovascular disease and epilepsy. SPECT has contributed to a better understanding of the pathophysiological processes and their dynamics after ischemic infarction. The method also provides essential insights in epileptics. In partial epilepsy, a focus of reduced or enhanced tracer activity can be ascertained, dependent on the timing of the examination, in the interictal and ictal stage respectively. Even in the early course of senile dementia of Alzheimer type, zones of diminished neuronal activity in temporo-parietal and frontal cortex are demarcated. Preliminary results in psychiatric diseases and parkinsonism need further confirmation. In this connection future interest will focus especially upon the use of receptor ligands.