Effect of reserpine on salivary gland radioiodine uptake in thyroid cancer

Nine patients with thyroid cancer were treated with reserpine in an attempt to reduce radiation exposure to the salivary glands from 100-150 mCi doses of I-131 therapy to thyroid remnants or metastases. Three control patients were not treated with reserpine but did receive 100-150 mCi of I-131. Parotid/background ratios of activity after radioablative doses of I-131 in patients not treated with reserpine were significantly higher than the patients treated with reserpine, and this was also true seven days after the radioablative dose. Combined therapy with reserpine, chewing gum, lemon candies, and hydration is suggested for the prevention of sialadenitis and xerostomia due to large doses of radioiodine.     

The effect of susceptibility of gadolinium contrast media on diffusion-weighted imaging and the apparent diffusion coefficient

RATIONALE AND OBJECTIVES: The development of parallel magnetic resonance imaging has resulted in the frequent use of diffusion-weighted imaging (DWI) in clinical medicine, which usually involves the use of contrast medium. However, gadolinium (Gd) contrast medium may have some effect on DWI and the apparent diffusion coefficient (ADC). The present study was performed to determine whether the magnetic susceptibility of contrast medium alters the DWI signal and the value of ADC in some imaging techniques. MATERIALS AND METHODS: Nonfat suppression DWI, short-time inversion recovery (STIR) combination, and chemical shift selective (CHESS) combination DWI were performed to examine 10 phantoms with gadolinium-meglumine gadopentetate (Gd-DTPA) dissolved at concentrations from 0.0005 to 0.1 mmol in physiologic saline as a contrast medium. The average pixel value and ADC of each method were determined. RESULTS: ADC showed no differences between before and after treatment with contrast medium for all imaging techniques with Gd considered distributed over the whole tumor. The signal intensity did not change on nonfat suppression or CHESS combination DWI, but deteriorated on STIR. CONCLUSIONS: ADC was not influenced by the magnetic susceptibility of contrast medium. In addition, it was suggested that the ability of tumor detection may be reduced if STIR is used as fat suppression.     

The effect of high-dose radioiodine treatment on lacrimal gland function in patients with differentiated thyroid carcinoma

PURPOSE: There are a limited number of case reports confirming the radioiodine (I-131) presence in tears and only a few case reports of lacrimal gland dysfunction after I-131 therapy. This study was designed to clarify whether lacrimal gland function can be affected by I-131 therapy. MATERIALS AND METHODS: We studied 100 eyes of 50 patients who had received high doses of I-131 for treatment of differentiated thyroid carcinoma and 100 eyes of 50 age- and sex-matched control individuals without a history of interfering conditions. The exposed group was studied at least 3 months after their last I-131 therapy. Dry eye symptoms and Schirmer test values (wetting level in millimeters per 5 minutes) of an exposed group were compared with those of an unexposed group. RESULTS: Fifty-one percent of the exposed eyes and 50% of the unexposed ones revealed at least 1 of the dry eye symptoms. There was no significant difference in symptoms between 2 groups, except for burning sensation and eye redness, which were significantly higher in the exposed eyes. A lower Schirmer test value was noted in the exposed group, 14.5 +/- 10.8 mm, when compared with that in controls, 18.2 +/- 11.0 mm (P = 0.016), and the relative risk of an abnormal Schirmer test in exposed cases to control group was 1.78 +/- 0.62. Correlation coefficient analysis showed no significant relationship between Schirmer test values and cumulative doses of administered I-131. CONCLUSIONS: Reduction in the tear secretion from lacrimal glands is seen after high-dose I-131 therapy; however, their symptoms are no greater than an unexposed population.     

Relationship between cumulative radiation dose and salivary gland uptake associated with radioiodine therapy of thyroid cancer

AIM: To estimate the individual absorbed dose to the parotid and submandibular salivary glands in radioiodine therapy and its dependence from the previous cumulative therapy. METHODS: Fifty-five patients with differentiated thyroid carcinoma after thyroidectomy received 1-21 GBq (131)I using single activities of 1-6 GBq. The patients were stratified according to the cumulative activities into low-activity (1-2 GBq), middle-activity (3-7 GBq), and high-activity groups (9-21 GBq). The time-activity curves over the respective salivary glands were derived from multiple static calibrated images measured for each patient up to 48 h after ingestion of the radioiodine therapy capsule with a gamma camera. Manually drawn regions of interests were used to determine the background activities and the activities arising from the salivary glands. The gland volumes were determined by ultrasonography using appropriate volume models. RESULTS: The median absorbed dose per administered activity of each single parotid and submandibular gland was about 0.15 Gy.GBq (range, 0.1-0.3 Gy.GBq(-1)) and 0.48 Gy.GBq(-1) (range, 0.2-1.2 Gy.GBq(-1)), respectively. The maximum uptake of both gland types was significantly lower for the high-activity than for the low-activity groups and correlated with the mean cumulative administered activity of the activity groups. CONCLUSION: The iodine uptake of salivary glands is significantly reduced, whereas the absorbed dose per administered (131)I activity was not significantly decreased during the course of therapy. Comparing the well-known dose-effect relationships in external radiation therapy, the absorbed dose per administered (131)I activity is too low to induce comparable radiation damage, suggesting an inhomogeneous distribution of (131)I in human salivary glands.     

The use of iodinated and gadolinium contrast media during pregnancy and lactation

The use of iodinated or gadolinium-based contrast media in pregnant or lactating women often causes concerns in the radiology department because of the principle of not exposing a fetus or neonate to any drugs. Because of the uncertainty about the use of contrast media during pregnancy and lactation, the Contrast Media Safety Committee of the European Society of Urogenital Radiology decided to review the literature and draw up guidelines. An extensive literature search was carried out and summarized in a report. Based on the limited information available, simple guidelines have been drawn up. The report and guidelines were discussed at the 11th European Symposium on Urogenital Radiology in Santiago de Compostela, Spain. Mutagenic and teratogenic effects have not been described after administration of gadolinium or iodinated contrast media. Free iodide in radiographic contrast medium given to the mother has the potential to depress fetal/neonatal thyroid function. Neonatal thyroid function should be checked during the 1st week if iodinated contrast media have been given during pregnancy. No effect on the fetus has been seen after gadolinium contrast media. Only tiny amounts of iodinated or gadolinium-based contrast medium given to a lactating mother reach the milk, and only a minute proportion entering the babys gut is absorbed. The very small potential risk associated with absorption of contrast medium may be considered insufficient to warrant stopping breast-feeding for 24 h following either iodinated or gadolinium contrast agents.Members of the Committee: H.S. Thomsen (Chairman, Denmark), S.K. Morcos (Secretary, United Kingdom), T. Almén (Sweden), P. Aspelin (Sweden), M.F. Bellin (France), H. Flaten (Amersham Health, Norway), J.Å. Jakobsen (Norway), A. Löwe (Schering, Germany), R. Oyen (Belgium), A. Spinazzi (Bracco, Italy), F. Stacul (Italy), A.J. van der Molen (The Netherlands), J.A.W. Webb (United Kingdom).     

The thyroid gland with low uptake lesions: evaluation by ultrasound

An ultrasound examination was performed in 401 patients who had isotopically cold, solitary lesions of the thyroid gland. Of the parameters studied, the level of echoes was the most useful in making the sonographic diagnosis: the rate of malignancy was extremely low both in hyperechoic and echo-free lesions. The presence of a peripheral, complete "halo" appeared to be helpful in differentiating benign lesions from malignant lesions. Approximately 20-25% of the lesions thought to be solitary on the radionuclide study were found to be multinodular on US. When fine-needle aspiration biopsy was used with US the need for surgical exploration of the thyroid gland was obviated in selected cases.     

Diffuse radioiodine lung uptake in miliary thyroid carcinoma metastases

A diffuse pattern of homogeneous tracer uptake is seen by I-131 scintigraphy in a patient with widespread miliary lung metastases due to papillary thyroid carcinoma. This case report emphasizes the need to include metastatic thyroid carcinoma in the differential diagnosis of miliary lung nodules.     

The developmental history of the gadolinium chelates as intravenous contrast media for magnetic resonance

The developmental history of the gadolinium chelates, which spans 30 years, is described, focusing, in part, on the seminal work with each of the major agents in use today. By examining this history, insight is gained into important issues of efficacy and safety, with valuable lessons to be learned from the mistakes made during this period. An overview of physicochemical characteristics and chemical structures is also provided. The review concludes with a discussion of current research directions involving this field, which is that of the intravenous contrast media for magnetic resonance, in the past 5 years.