The best approach to radioiodine dose selection in the treatment of Graves' hyperthyroidism remains highly controversial. The formula to calculate the individual dose of 131 I to be delivered has been used for half a century and takes into account the thyroid mass, the effective half-life and the maximum uptake of 131 I. The objective of the present study was to evaluate the accuracy of this formula by determining the relationship between the administered dose of 131 I calculated to deliver a target dose of 50 Gy to the thyroid and the actual exact organ dose. We further analyzed if therapeutic success, defined by euthyroidism following the individually calculated dose, can be predicted by different pretreatment parameters and particularly by organ dose.One hundred patients with a first episode of Graves' disease and who had received optimal thyroid irradiation after precise dosimetry were retrospectively reviewed. The patients were categorized according to their thyroid function (plasma free thyroxine (T 4 ) serum concentration) as eu-, hyperor hypothyroid during and 1 year after treatment. The relationship between the administered dose and organ dose was assessed by simple regression. We compared free T 4 , free tri-iodothyronine, thyroid weight, the number of patients with antithyroperoxidase antibodies and TSH receptor autoantibodies, 24 h urinary iodine excretion, 131 I uptake, and the exact dose of 131 I delivered to the thyroid as pretreatment variables. Although we found a correlation between administered dose (mCi) and organ dose (Gy) (r = 0.3, P = 0.003), the mean coefficient of variation for organ dose was 45%. Individualized radioiodine therapy enabled euthyroidism in 26% of patients and failed in 74% of patients (33% had persistent or recurrent hyperthyroidism and 41% permanent hypothyroidism). 131 I uptake was significantly higher in the hyperthyroidism group in comparison with the euthyroid group. However, organ dose and other pretreatment variables did not differ among the three groups.In conclusion, these results confirm the low performance of individual dosimetry using what are established ratios, since the delivered dose to the gland, although correlated to the intended dose, is highly variable. The finding that other usual pretreatment variables are not different between groups, gives little hope for improving the way of calculating the ideal dose of radioiodine. We suggest to those not yet ready to give a standard or an ablative dose for Graves' hyperthyroidism that they abandon this way to calculate the 131 I dose.

The present method enables the noninvasive assessment of mean pulmonary arterial pressure from magnetic resonance phase mapping by computing both physical and biophysical parameters. The physical parameters include the mean blood flow velocity over the cross-sectional area of the main pulmonary artery (MPA) at the systolic peak and the maximal systolic MPA cross-sectional area value, whereas the biophysical parameters are related to each patient, such as height, weight, and heart rate. These parameters have been measured in a series of 31 patients undergoing right-side heart catheterization, and the computed mean pulmonary arterial pressure value (Ppa(Comp)) has been compared with the mean pressure value obtained from catheterization (Ppa(Cat)) in each patient. A significant correlation was found that did not differ from the identity line Ppa(Comp) = Ppa(Cat) (r = 0.92). The mean and maximal absolute differences between Ppa(Comp) and Ppa(Cat) were 5.4 and 11.9 mmHg, respectively. The method was also applied to compute the MPA systolic and diastolic pressures in the same patient series. We conclude that this computed method, which combines physical (whoever the patient) and biophysical parameters (related to each patient), improves the accuracy of MRI to noninvasively estimate pulmonary arterial pressures.

Amongst urinary tests, the combined use of HPLC/ED determination of normetanephrine and metanephrine seems the most effective screening strategy for the diagnosis of pheochromocytoma. The older total metanephrine photometric assay is grieved by analytical interferences.

Purpose:To investigate the feasibility of assessing, noninvasively, aortic pulse pressure (APP) and pulse wave velocity (PWV) in the ascending aorta of young adults by means of velocity-encoded magnetic resonance (MR) imaging. Materials and Methods:In a series of 11 healthy volunteers, velocity-encoded MR imaging provided pairs of magnitude and phase-contrast images. Blood flow velocity and aortic cross-sectional area (CSA) were determined with a 30-msec temporal resolution. A model analysis revealed that variation in aortic CSA and in maximal blood flow velocity throughout systole could be used to estimate APP and, hence, to derive PWV by means of two different methods. Results:Mean Ϯ SD values of the APP for the series were 54.2 Ϯ 16.4 mmHg (range 32.2-84.1 mmHg). The ascending aortic PWV mean Ϯ SD values were 5.03 Ϯ 1.10 m/second and 5.37 Ϯ 1.23 m/second according to the two methods, and both estimates were not significantly different (95% confidence level). Conclusion:These results are in agreement with previously published data, suggesting that APP and PWV can be determined, noninvasively, in young adults using MRI.

Bone mineral content is reliably measured by dual energy X-ray absorptiometry (DXA), if manufacturers' recommendations and quality control (QC) procedures are followed. Several phantoms (Hologic anthropomorphic spine phantom, the Groupe de Recherche et d'Informations sur les Osteoporoses (GRIO) test objects and the European semi-anthropomorphic phantoms) were used to evaluate reproducibility, linearity, accuracy and spatial resolution of two DXA devices in vitro. These parameters were also evaluated in vivo from measurements performed on 120 volunteer patients. It was found that when one device (a single beam monodetector QDR 1000) is replaced by another (a fan beam multidetector QDR 4500/A), the novel combination of procedures described here, ensures that the accuracy of DXA study results is maintained when both devices are used in succession for the same patient. To study the possible responses in clinical situations, the influence of bone environment (soft and adipose tissues) was also evaluated. In both systems, similar performances (in vitro coefficients of variation of 0.5%) were established. At extreme bone density values, slight differences in linearity were found, as well as differences in accuracy and spatial resolution. Lumbar spine and femoral neck measurements were performed with both systems in 120 volunteers, both measurements being made on the same day. The corresponding bone mineral density (BMD) values were highly correlated (r2 = 0.985 for lumbar spine and 0.948 for the femoral neck), and the mean BMD differences were 0.68% and 0.37% for each anatomical site, respectively. Although small, these differences add to the precision error of the method, which is near 1%. A calibration curve has to be obtained in order that both devices can be equally used in regular clinical study. We concluded that when a DXA system is replaced by a new one, appropriate QC procedures must be strictly observed.