Biomedical subjects

M Monsieurs

Publications and source records attributed to M Monsieurs.

6 recordsLinked to original sources

PubMed2002

Thyroid uptake and radiation dose after (131)I-lipiodol treatment: is thyroid blocking by potassium iodide necessary?

In radionuclide therapy with iodine-131 labelled pharmaceuticals, free (131)I may be released and trapped by the thyroid, causing an undesirable radiation burden. To prevent this, stable iodide such as potassium iodide (KI) can be given to saturate the thyroid before (131)I is administered. The guidelines of the European Association of Nuclear Medicine do not, however, recommend special precautions when administering (131)I-lipiodol therapy for hepatocellular carcinoma. Nevertheless, some authors have reported (131)I uptake in the thyroid as a consequence of such therapy. In this study, the influence of prophylactic KI on the thyroid uptake and dose (MIRD dosimetry) was prospectively investigated. (131)I-lipiodol was given as a slow bolus selectively in the proper hepatic artery or hyperselectively in the right and/or left hepatic artery. Patients were prospectively randomised into two groups. One group received KI in a dose of 100 mg per day starting 2 days before (131)I-lipiodol administration and continuing until 2 weeks after therapy (KI group; n=31), while the other group received no KI (non-KI group; n=37). Thyroid uptake was measured scintigraphically as a percentage of administered activity 7 days after (131)I-lipiodol ( n=68 treatments). The absorbed radiation dose to the thyroid was assessed by scintigraphy after 7 and 14 days using a mono-exponential fitting model and MIRD dosimetry ( n=40 treatments). The mean activity of (131)I-lipiodol administered was 1,835 MBq in a volume of 2 ( n=17) or 4 ( n=51) ml. Thyroid uptake was lower in the KI group, being 0.23%+/-0.06% of injected activity ( n=31) compared with 0.42%+/-0.20% in the non-KI group ( n=37); the mean thyroid dose was 5.5+/-1.6 Gy in the KI group ( n=19) versus 11.9+/-5.9 Gy in the non-KI group ( n=21). These differences were statistically significant ( P<0.001). No effect of the amount of added cold lipiodol (4 vs 2 ml total volume) or selectivity of (131)I-lipiodol administration was evident ( P>0.1). (131)I-lipiodol is associated with a generally low thyroid uptake and dose that may be significantly decreased by KI premedication. Given the low cost and the very good tolerance of the KI treatment, we believe the use of KI should be recommended in the majority of the patients.

Carcinoma, Hepatocellular↗

PubMed2001

Translocation frequencies measured in patients one year after radioactive iodine therapy for thyrotoxicosis.

PURPOSE: To investigate the incidence of translocations induced by iodine-131 therapy in thyrotoxicosis patients 1 year after the administration of the radiolabelled compound. MATERIALS AND METHODS: Tricolour FISH with whole-chromosome-specific probes for chromosomes 2, 4 and 8 was used for scoring translocations. From the genomic translocation frequencies, derived using the Lucas formula, equivalent whole-body doses were calculated, based on the in vitro (60)Co gamma-ray dose-response curve. RESULTS: A total of 101 translocations were observed in 4864 metaphases, 63% being of the two-way type. In the control group used for obtaining dose-response data, nine translocations were observed in 5278 metaphases, 55% being two-way translocations. No correlation was found between the observed frequency of translocations and administered radioactivity. Using the in vitro dose-response, an estimated average dose for the group of nine patients of 0.79 +/- 0.22Gy was obtained. Compared with frequencies following the assumption that the involvement of a particular chromosome in a two-break exchange-type aberration is proportional to its DNA content, chromosome 4 was more frequently involved and chromosomes 2 and 8 less frequently involved in chromosomal rearrangements. CONCLUSION: This study shows that (131)I therapy for thyrotoxicosis patients induced translocations, especially in chromosome 4, which could be detected 1 year after the administration of the radiolabelled compound.

Adult↗

PubMed2000

Nonuniform transmission in brain SPECT using 201Tl, 153Gd, and 99mTc static line sources: anthropomorphic dosimetry studies and influence on brain quantification.

UNLABELLED: Nonuniform attenuation correction in brain SPECT can be done routinely by means of additional gamma transmission CT (TCT) measurements, using different commercially available line-source isotopes, 201Tl, 153Gd, and 99mTc are among the most commonly used isotopes, depending on practical and cost-effectiveness issues. We have measured additional radiation burden from static uncollimated brain SPECT transmission sources for these isotopes. The influence of the transmission isotope on brain quantification was also measured and compared with uniform attenuation correction for phantom and human data. Full iterative transmission and emission reconstruction were compared with filtered backprojection techniques. METHODS: Rod sources with 201Tl, 153Gd, and 99mTc were used on a triple-head gamma camera. Dosimetry was performed using LiF TLD-100 pellets and an anthropomorphic RANDO phantom. Effective dose equivalents were calculated on the basis of measured and extrapolated absorbed doses. For brain activity measurements, a Hoffman phantom was used. Images were corrected for scatter (triple-energy window) and were reconstructed by Chang attenuation correction and filtered backprojection as well as full iterative reconstruction (ordered-subsets expectation maximization [OSEM]). To study the effect of inhomogeneous bone attenuation, realistic measurements were performed on 10 young, healthy volunteers with 153Gd TCT. After stereotactic image realignment, a volume-of-interest analysis normalized to total counts was performed. RESULTS: Brain SPECT-TCT using 201Tl, 153Gd, and 99mTc produced total effective dose-rate equivalents of 50.3 +/- 11.2, 32.0 +/- 2.7, and 71.1 +/- 7.1 microSv/GBq x h, respectively, representing dose equivalents of 18.6, 11.9, and 26.3 microSv for a typical 20-min brain SPECT scan at maximal used source strength. Standardized quantification resulted in insignificant differences between the isotopes and methods (Chang versus OSEM) used for nonuniform correction. Iterative reconstruction enhanced image contrast and provided more accurate gray-to-white matter ratios. Between nonuniform and uniform attenuation with an optimized attenuation coefficient, slight central discrepancies were found for volunteer studies. Significantly lower intersubject variation was found for nonuniform corrected values in infratentorial and posterior brain regions. CONCLUSION: Brain transmission scanning using 201Tl, 153Gd, or 99mTc results in limited effective radiation dose equivalents compared with the typical radiation burden. Relative brain perfusion quantification is not significantly different for the various nonuniform TCT isotopes. Iterative reconstruction improves gray-to-white contrasts but has no significant influence on brain perfusion semiquantification. Nonuniform attenuation correction decreases intersubject variability in the posterior brain regions that were compared, which may lead to improved sensitivity toward clinical applications.

Adult↗

PubMed1998

Real-life radiation burden to relatives of patients treated with iodine-131: a study in eight centres in Flanders (Belgium).

In view of the EURATOM 96/29 [1] regulations, a prospective multicentre study was performed to evaluate the present guidelines given to relatives of patients treated with iodine-131 for both thyroid carcinoma and thyrotoxicosis, based on the real-life radiation burden. This study comprised 166 measurements carried out on a group of 94 relatives of 65 patients. All relatives wore a thermoluminescent dosemeter (TLD) on the wrist for 7 days. Sixty-one relatives agreed to wear another TLD for an additional 7 days. TLD were placed on nine patients' bedside tables. The eight participating centres were arbitrarily divided into three groups according to the period of time they advised their patients to sleep separately. Groups I, II and III respectively advised their patients to sleep separately for 0, 7-10 and 14-21 days. The median dose received by in-living relatives of thyroid carcinoma patients during the 14 days following hospital discharge was 281 microSv (doses to infinity not calculated); the median dose to infinity received by in-living relatives of ambulatory treated thyrotoxicosis patients was 596 microSv, as compared with 802 microSv for in-living relatives of hospitalised thyrotoxicosis patients. In general the children of patients received a significantly (P < 0.1) lower mean dose than their partners. For thyroid carcinoma patients, only two relatives out of 19 (10%) exceeded the EURATOM 96/29 limit of 1 mSv/year. For thyrotoxic patients, 28% of relatives exceeded the EURATOM 96/29 limit, but none of them were relatives of patients who followed guidelines for 21 days. The results of this study indicate that sleeping separately for 7 days, after a period of hospitalisation of 2-3 days, will usually be sufficient for thyroid carcinoma patients. For thyrotoxicosis patients, up to 21 days of sleeping separately could be necessary in order to strictly abide by EURATOM 96/29. Therefore, the authors propose the implementation of a non-rigid dose constraint for people who "knowingly and willingly" help patients treated with 131I, while still following the ALARA principle.

Adolescent↗

PubMed1997

201Tl scintigraphy does not allow visualization of the thyroid in euthyroid and hyperthyroid patients treated with amiodarone.

A retrospective study was performed to evaluate the usefulness of thallium scintigraphy for visualization of thyroid morphology and function. Moreover, applying absolute quantitation, we wished to confirm the qualitatively reduced 99Tc(m) uptake reported by Wiersinga et al. in both euthyroid and hyperthyroid patients treated with amiodarone. Over a period of 2 years (1995-96), 10 patients (group A; 2 females, 8 males, mean age 68.6 years, range 61-74 years) receiving amiodarone treatment for cardiac arrhythmias for at least 4 months were referred for exploration of either hyperthyroidism (n = 4) or for exclusion of parathyroid adenoma (n = 6). During the same period, 17 patients (group B; 10 females, 7 males, mean age 62 years, range 19-91 years) referred for Tc-Tl subtraction scintigraphy, and in whom follow-up revealed no thyroid or parathyroid pathology, were used as controls. In all patients, thyroid status was assessed by thyroid function tests. 201Tl and 99Tc(m) uptake was calculated as a percentage of the injected dose, taking account of net injected counts and background and isotope decay correction. Original images were scored using a 2-point scoring system (0 = poor, 1 = fair or good). Uptake of both 99Tc(m) and 201Tl was significantly reduced in group A (99Tc[m]: 0.16 +/- 0.21%; 201Tl: 0.30 +/- 0.21%; mean +/- S.D.) compared to group B (99Tc[m]: 1.58 +/- 1.07%; 201Tl: 0.72 +/- 0.37%) (P < 0.005). The mean relative reduction in 99Tc(m) uptake was more pronounced (90% decrease) than that of 201Tl (58% decrease). In group A, the 99Tc(m) and 201Tl image quality was poor in 10 of 10 and 8 of 10 patients respectively. In group B, the 99Tc(m) and 201Tl image quality was poor in 3 of 17 and 4 of 17 patients respectively. The decreased uptake of 201Tl may reflect the inhibitory effect of iodides on adenyl cyclase and its stimulation by TSH. In conclusion, the data presented confirm the qualitatively reduced pertechnetate uptake reported by Wiersinga et al. Furthermore, 201Tl uptake by the thyroid in euthyroid or hyperthyroid patients treated with amiodarone is also reduced. Although quantitatively less pronounced, it does not allow proper visualization of the thyroid.

Adult↗

PubMed1995

Bordetella hinzii sp. nov., isolated from poultry and humans.

A polyphasic taxonomic study that included DNA-rRNA hybridizations, DNA-DNA hybridizations, DNA base ratio determinations, whole-cell protein and fatty acid analyses, and an examination of classical phenotypic characteristics was performed in order to classify human and veterinary isolates that resemble Bordetella avium. Twelve poultry isolates and two human isolates were assigned to a new species, for which we propose the name Bordetella hinzii. The position of this organism in the family Alcaligenaceae and various genotypic, phenotypic, and chemotaxonomic characteristics are described.

Animals↗