Abstract : Radioiodine thyroid uptake measures the percentage of 131I that accumulates in the thyroid at selected times following ingestion. Our objective was to investigate the errors underlying erroneous Radioiodine Thyroid Uptake (RITU) values experienced at Mubarak Al-Kabeer Hospital and develop a quality assurance method. The RITU procedure requires determination of the count rate from 1311 by a NaI(TI) scintillation detector. The electronic stability of the Nal(T1) detector was investigated along with attenuation effects of the metallic rod distance indicator. Positional effects on the observed count rates were investigated for both a thyroid phantom and "'I capsules placed in a neck phantom. The effect of depth of the "'I capsules in the neck phantom was investigated. The effect of the metallic rod was investigated for a series of 79 patients over a two year period. The accuracy of the manufacturer's quoted activity for the "'I capsules were investigated over this two-year period. The Biodex thyroid uptake system was found to be stable (+ 2%) electronically over the investigation period. The metallic rod was found to be capable of introducing an attenuation of up to 40% for the '31I capsules and 4% for the thyroid phantom. The count rate for both capsule and patient followed an inverse square law thus distances need to be standardized to 0.5 cm at the 28.5 cm distance between the source and detector. Without the rod in place patient motion produced errors of 60% in the RITU values. The unknown thyroid depth introduces a 10% error per cm that the thyroid is away from the assumed 2.6 cm depth. The 131I capsules were observed to have variation of +2% when normalized to nominal activity. The 131I uptake determination requires that no attenuating rods be placed in the direct path of the scintillation detector. The distance has to be stable to within 0.5 cm thus the patient should be supine or a head rest provided. The thyroid's unknown depth limits the precision of the RITU value. The 131I capsules precision is to + 2% of the manufacturer activity thus a capsule's count rate can be verified even after use for an erroneous RIM value.

Abstract : There is sufficient evidence that 5-hydroxytryptamine, (5-HT) may play a physiological role in the control of motor functions of the gastrointestinal tract and its appendage, the gallbladder. This amine has met most of the criteria required for a neurotrans¬mitter role within the enteric neural system and may participate in the regulation of inter-neuronal functions. However, no investigator has so far attempted to characterize the receptor on which 5-HT acts in the biliary tract. There is some confusion about the classification of the types of 5-HT receptors and their nomenclature. Bradley et al. (1986) have reviewed the current status, and the original "D" and "M" receptors of Gaddum and Picarelli (1957) have now been equated with the 5-HT2 and 5-HT3 receptors more recently proposed. The 5-HT1 receptors appear to be a heterogenous group and for lack of adequate knowledge, have been proposed to be called as "5-HT1-like" receptor. With the recent availability of selective agonists and antagonists of the 5-HT receptors it is possible to functionally characterize the different 5- HT receptors involved in 5-HT action. In the present study, qualitative effects produced by different 5-HT receptors were subjected to pharmacological manipulations with the object of delineating the functional role of each 5-HT receptor type in the sheep gallbladder fundus and the sphincter of Oddi. In vitro studies on the fundus of gall bladder were carried out using an isolated tissue organ bath and a microorgan bath was employed for the sphincter of Oddi rings. The result of the present study indicated that all three types of 5-HT receptors were involved in the motor responses of the sheep gallbladder fundus as well as sphincter of Oddi. In the sheep gallbladder fundus and sphincter of Oddi, the contraction of the smooth muscle was due to activation of cholinergic mechanisms, which was mediated through muscarinic receptors ptors and relaxations arose from an activation of nonadrenergic, noncholinergic (NANC) neuronal mechanism, possibly purinergic. The serotonergic mechanisms were concerned with facilitation of neuronal release of the transmitters involved in contraction and relaxation of the smooth muscle via the 5-HT3 presynpatic receptors on the cholinergic and purinergic nerves respectively. In the gallbladder fundus the "5-HT1 -like" and 5-HT2 receptors were concerned with relaxation and contraction respectively. In the sphincter of Oddi the "5-HT1 - like" and 5-HT2 receptors had functions opposite to those observed in the fundus of the gallbladder. The "5-HT1 -like" receptor was responsible for contraction of the smooth muscle, whereas relaxation appeared to be favoured by 5-HT2 receptor activation.

Abstract : 99mTc pertechnetate thyroid scintigraphy is a valuable procedure in many clinical situations. However, if a thyroid uptake is required, non-utilization of uptake determination by quantitative methods for this test necessitates performing a radioiodine uptake measurement. The aims of this study were: to establish the range of 99mTc pertechnetate thyroid uptake (TcTU) in euthyroid subjects; to study the correlation between TcTU & 131 I thyroid uptake; to derive a conversion formula from TcTU to 24-hour iodine uptake and to study the relationship between TcTU, clinical parameters and thyroid hormone levels. Material & Methods: This is a prospective consecutive case study conducted over a period of one year where patients referred for both thyroid uptake and scintigraphy were included. TcTU was derived from 20-minute thyroid image performed using 99m Tc pertechnetate and a gamma camera equipped with a pinhole collimator. 131 I uptake was measured using a counting probe 24 hours after oral administration of 131 I. Results & Discussion: 229 subjects (47 males, 182 females) were studied. Among 79 euthyroid patients TcTU was 1.7 + 1.4. In the hyperthyroid and subclinical hyperthyroid groups mean TcTU was 11.8 + 9.6 and 2.4 + 3.1, respectively. A highly significant positive correlation was found between TcTU and 131 I uptake (r=0.837, P<0.001). Both studies showed differences between the euthyroid & hyperthyroid groups and between the frank hyperthyroid & subclinical hyperthyroid groups. Both parameters showed significant correlations with some of the clinical parameters, TFTs, and the size of the thyroid gland. TcTU, however, in many of these comparisons had more significant and stronger associations than 24-hour 131 I uptake. A conversion equation was derived (131 I uptake =14.6 In [TcTU] + 26.9) with a correlation coefficient R2 of 0.67. Conclusion: TcTU is an additional reliable quantitative parameter which potentially eliminates the need for a separate 131 I uptake measurements in patients with thyroid disorders.

Abstract : Metabolic bone disease due to hyperparathyroidism is characterized by increased bone resorption and new bone formation. 99mTc- hexakis-2-methoxyisobutylisonitrile (99mTc MIBI) accumulation in cells is controlled by metabolic function and cell viability. F