Prognostic Value of Serum Tumor Markers in Medullary Thyroid Cancer Patients Undergoing Vandetanib Treatment.

Tyrosine kinase inhibitors (TKIs) such as vandetanib have shown clinical effectiveness in advanced medullary thyroid cancer (MTC). During TKI treatment, fluctuations in the tumor markers carcinoembryonic antigen (CEA) and calcitonin (CTN) are frequently observed. Their role for treatment monitoring and the decision-making process has not been fully elucidated yet.Twenty-one patients (male, 16, female, 5; mean age, 49 ±â€Š13 years) with progressive MTC receiving vandetanib (300 mg orally per day) were considered. Tumor restaging was performed every 3 months including contrast-enhanced computed tomography (CT). Response was assessed according to recent criteria (Response Evaluation Criteria in Solid Tumors, RECIST 1.1). Additionally, CEA and CTN were measured at the day of CT imaging and alterations observed in tumor markers were compared to respective imaging findings (partial response, PR; stable disease, SD; progressive disease, PD).During long-term follow-up (510 ±â€Š350 days [range, 97-1140 days]), CTN and CEA levels initially dropped in 71.4% and 61.9% of the patients followed by fluctuations in serum marker levels. A rise in CTN ≥39.5% between 2 subsequent measurements (defined by ROC analysis) had a sensitivity of 70.6% and a specificity of 83.2% in predicting PD with an accuracy of 82.0% (area under the curve (AUC), 0.76). Oscillations in CEA levels were not predictive for PD.Whereas tumor marker fluctuations in MTC patients undergoing TKI treatment are a frequent phenomenon, a significant rise in CTN ≥40% turns out to as an early indicator of tumor progression.

The absorbed dose to blood from blood-borne activity.

The radiation absorbed dose to blood and organs from activity in the blood is relevant for nuclear medicine dosimetry and for research in biodosimetry. The present study provides coefficients for the average absorbed dose rates to the blood from blood-borne activity for radionuclides frequently used in targeted radiotherapy and in PET diagnostics. The results were deduced from published data for vessel radius-dependent dose rate coefficients and reasonable assumptions on the blood-volume distribution as a function of the vessel radius. Different parts of the circulatory system were analyzed separately. Vessel size information for heart chambers, aorta, vena cava, pulmonary artery, and capillaries was taken from published results of morphometric measurements. The remaining blood not contained in the mentioned vessels was assumed to reside in fractal-like vascular trees, the smallest branches of which are the arterioles or venules. The applied vessel size distribution is consistent with recommendations of the ICRP on the blood-volume distribution in the human. The resulting average absorbed dose rates to the blood per nuclear disintegration per milliliter (ml) of blood are (in 10(-11) Gy·s(-1)·Bq(-1)·ml) Y-90: 5.58, I-131: 2.49, Lu-177: 1.72, Sm-153: 2.97, Tc-99m: 0.366, C-11: 4.56, F-18: 3.61, Ga-68: 5.94, I-124: 2.55. Photon radiation contributes 1.1-1.2·10(-11) Gy·s(-1)·Bq(-1)·ml to the total dose rate for positron emitters but significantly less for the other nuclides. Blood self-absorption of the energy emitted by ß-particles in the whole blood ranges from 37% for Y-90 to 80% for Tc-99m. The correspondent values in vascular trees, which are important for the absorbed dose to organs, range from 30% for Y-90 to 82% for Tc-99m.

The limit of detection in scintigraphic imaging with I-131 in patients with differentiated thyroid carcinoma.

Radioiodine scintigraphy influences staging and treatment in patients with differentiated thyroid carcinoma. The limit of detection for fractional uptake in an iodine avid focus in a scintigraphic image was determined from the number of lesion net counts and the count density of the tissue background. The count statistics were used to calculate the diagnostic activity required to elevate the signal from a lesion with a given uptake significantly above a homogeneous background with randomly distributed counts per area. The dependences of the minimal uptake and the minimal size of lesions visible in a scan on several parameters of influence were determined by linking the typical biokinetics observed in iodine avid tissue to the lesion mass and to the absorbed dose received in a radioiodine therapy. The detection limits for fractional uptake in a neck lesion of a typical patient are about 0.001% after therapy with 7000 MBq, 0.01% for activities typically administered in diagnostic assessments (74-185 MBq), and 0.1% after the administration of 10 MBq I-131. Lesions at the limit of detection in a diagnostic scan with biokinetics eligible for radioiodine therapy are small with diameters of a few millimeters. Increasing the diagnostic activity by a factor of 4 reduces the diameter of visible lesions by 25% or about 1 mm. Several other determinants have a comparable or higher influence on the limit of detection than the administered activity; most important are the biokinetics in both blood pool and target tissue and the time of measurement. A generally valid recommendation for the timing of the scan is impossible as the time of the highest probability to detect iodine avid tissue depends on the administered activity as well as on the biokinetics in the lesion and background in the individual patient.

Self-irradiation of the blood from selected nuclides in nuclear medicine.

Nuclear medicine dosimetry and research in biodosimetry often require the knowledge of the absorbed dose to the blood. This study provides coefficients for the absorbed dose rates to the blood related to the activity concentration in the blood as a function of the vessel radius for radionuclides commonly used in targeted radiotherapy and in PET-diagnostics: C-11, F-18, Ga-68, Y-90, Tc-99 m, I-124, I-131, and Lu-177. The energy deposition patterns after nuclear disintegrations in blood vessel lumina (cylinders homogeneously filled with blood) with radii from 0.01 to 25.0 mm were simulated with the Monte-Carlo radiation transport code MCNPX. An additional contribution from photon radiation from activity in blood in the remainder of the body was taken into account based on a reasonable blood distribution model. The fraction of energy absorbed from non-penetrating radiation in the blood is low in thin blood vessels but approaches the total energy emitted by particles with increasing lumen radius. For photon radiation, irradiation to blood in small vessels is almost completely due to radioactive decays in distant blood distributed throughout the body, whereas the contribution from activity in the vessel becomes dominant for lumen radii exceeding 13 mm. The dependences of the absorbed dose rates on the lumen radius can be described with good accuracy by empirical functions which can be used to determine the absorbed doses to the blood and to the surrounding tissue.

Molecular radiotherapy: the NUKFIT software for calculating the time-integrated activity coefficient.

PURPOSE: Calculation of the time-integrated activity coefficient (residence time) is a crucial step in dosimetry for molecular radiotherapy. However, available software is deficient in that it is either not tailored for the use in molecular radiotherapy and/or does not include all required estimation methods. The aim of this work was therefore the development and programming of an algorithm which allows for an objective and reproducible determination of the time-integrated activity coefficient and its standard error. METHODS: The algorithm includes the selection of a set of fitting functions from predefined sums of exponentials and the choice of an error model for the used data. To estimate the values of the adjustable parameters an objective function, depending on the data, the parameters of the error model, the fitting function and (if required and available) Bayesian information, is minimized. To increase reproducibility and user-friendliness the starting values are automatically determined using a combination of curve stripping and random search. Visual inspection, the coefficient of determination, the standard error of the fitted parameters, and the correlation matrix are provided to evaluate the quality of the fit. The functions which are most supported by the data are determined using the corrected Akaike information criterion. The time-integrated activity coefficient is estimated by analytically integrating the fitted functions. Its standard error is determined assuming Gaussian error propagation. The software was implemented using MATLAB. RESULTS: To validate the proper implementation of the objective function and the fit functions, the results of NUKFIT and SAAM numerical, a commercially available software tool, were compared. The automatic search for starting values was successfully tested for reproducibility. The quality criteria applied in conjunction with the Akaike information criterion allowed the selection of suitable functions. Function fit parameters and their standard error estimated by using SAAM numerical and NUKFIT showed differences of <1%. The differences for the time-integrated activity coefficients were also <1% (standard error between 0.4% and 3%). In general, the application of the software is user-friendly and the results are mathematically correct and reproducible. An application of NUKFIT is presented for three different clinical examples. CONCLUSIONS: The software tool with its underlying methodology can be employed to objectively and reproducibly estimate the time integrated activity coefficient and its standard error for most time activity data in molecular radiotherapy.

Improved follow-up of patients with differentiated thyroid carcinoma. The quantitative detection limit of 131I uptake in diagnostic scans.

AIM: Physicians typically are unaware of the radioiodine uptake (RIU) detection limit (LoD) on scintigrams of differentiated thyroid carcinoma (DTC) patients. We evaluated a novel method to determine LoD as a quantitative upper limit for RIU in negative scans and as a value to contextualize faint visible uptake. PATIENTS, METHODS: To test whether LoD is related to physicians' ratings, RIU and LoD were calculated from scintigraphic count statistics for 120 static planar neck scans and were compared with the ratings of five nuclear medicine specialists blinded to patient/scan characteristics regarding visible cervical uptake. Scans were acquired on days 1 (d1) and 2 (d2) post-administration of 298 ± 30 MBq iodine-131 in 60 consecutive DTC patients after recombinant human thyrotropin (rhTSH) or thyroid hormone withdrawal (THW) (n = 30 each). RESULTS: Indicating good inter-observer agreement, ≥ 4 readers concurred regarding 56 (93.3%) [54 (90.0%)] d1[d2] scans. Seventeen scans from 12 patients received ≥ 3 positive votes; in 15 (88.2%), RIU exceeded LoD. RIU assessed from regions-of-interest over former thyroid beds in scans with ≤ 2 positive votes was typically below the LoD (99/103 scans, 96.1%). In 48 patients with ≤ 2 positive votes in both scans, LoD was a median 0.0094% (0.0050%) in d1(d2) images and was significantly lower (p < 0.01) on early or late scans in 22 euthyroid rhTSH patients versus 26 hypothyroid THW patients. CONCLUSION: LoD data obtained by the proposed method closely reflect nuclear medicine specialists' scan ratings and provide comparators in serial scintigrams, improving diagnostic 131I imaging accuracy in differentiated thyroid carcinoma.

Patients with recurrent glioblastoma multiforme. Initial experience with p-[(131)I]iodo-L-phenylalanine and external beam radiation therapy.

AIM: The objective of this study was to assess the feasibility, dosimetry, tolerability and efficacy of systemically administrated p-[(131)I]iodo-L-phenylalanine ((131)IPA) combined with hypo-fractionated external beam radiation therapy (EBRT) in patients with recurrent glioblastoma multiforme (GBM). PATIENTS, METHODS: Five patients (2 women, 3 men, aged 27-69) with recurrent GBM and exhaustion of regular therapy options were included. All had a positive O-(2-[(18)F]Fluoroethyl)-L-tyrosine positron emission tomography (FET-PET) and pretherapeutic dosimetry was performed. Tumour targeting was verified by (131)IPA-SPECT up to six days after radiotracer administration. After (131)IPA therapy, patients were treated with hypo-fractionated EBRT in six fractions of 5 Gy (n = 4) or in eleven fractions of 2 Gy in one case. RESULTS: Based on the individual dosimetry, the patients received a single intravenous administration of 2 to 7 GBq of (131)IPA, resulting in radiation absorbed doses to the blood of 0.80-1.47 Gy. The treatment was well tolerated; only minor complaints of nausea and vomiting that responded to ondansetron and pantoprazol were noticed in the first two patients. After preventive medication, the last three patients had no complaints during therapy. In none of the patients a decrease of leukocyte or thrombocyte counts below the baseline level or the lower normal limit was observed. Tumour doses from (131)IPA were low (≤ 1 Gy) and all patients died three to eight (median 5.5) months after therapy. CONCLUSION: In this initial experience, treatment of GBM with (131)IPA in combination with EBRT was demonstrated to be safe and well tolerated, but less effective than suggested by the animal studies.

Radioiodine therapy of metastatic lesions of differentiated thyroid cancer.

Seventy years after the first successful radioiodine treatment of metastatic differentiated thyroid cancer (DTC), radioiodine (131I) therapy for this type of tumor is still without alternative. During the last decade, some key issues such as individual dosimetry, and preparation of 131I therapy by recombinant human TSH have been addressed, but this has not yet lead to conclusive results; furthermore a number of questions related to indication, preparation, and treatment protocol of 131I therapy still remain unanswered. In this review, we will address the literature pertaining to the latest developments in the field of 131I therapy of advanced DTC and we will give an overview of the state of the art regarding patient preparation, dosimetry, and therapy.

Identification of factors associated with risk of fall using a force platform and power spectrum analysis technique.

The purpose of this retrospective study was to investigate some parameters of neuromuscular performance of the lower limbs in a population cross-section and their relationship to the risk of falls, using a force platform (FP). Individuals from the Lower Franconia population were invited by public advertisement. Out of a total of 1720 invited subjects 50-90 years of age, the successful completion of all tests were achieved by 807 women, age 66.4±9.3, and 442 men, age 64.0±9.2. A novel FP measured the time series of vertical forces over 10 s during 3 kinds of tests: tandem stand with eyes closed, knee bends, and chair rise. Proprietary software captured the peak force and calculated the power density distribution (PSD), intended to characterize balance and power through the FP. Grip strength as a common geriatric force test was dynamometrically measured for comparison. The parameters were related to the number of falls in the past 12 months in both genders. Mean PSD showed little age dependency and was not related to falls in tandem stance. Peak forces and power over 10 s knee bends showed a larger age-related decrease in men than in women and these parameters were related to falls (p<0.001), whereas they were not related to falls in the chair rise test. Chair rise time and grip strength was related to falls in women (p<0.01). The PSD obtained from the tandem test with eyes closed did not provide a sensitive parameter associated with falls. Knee bends may be a meaningful FP screening test that justifies further studies of physical performance related to the risk of falls, whereas chair rise and grip measurements provided inferior information in this study.

The use of dosimetry in the treatment of differentiated thyroid cancer.

The standard treatment for the ablation of thyroid remnant tissue following surgery as well as for the treatment of iodine avid metastases in patients suffering from differentiated thyroid cancer (DTC) is therapy with radioactive iodine. Mostly fixed standard activities are used with the inherent risk of under- or overdosing the patient. Therefore, the rationale for using a dosimetry-based approach is to replace the conventional fixed activity regimen by a patient-tailored approach which allows the administered therapeutic activity to be increased while avoiding unwanted side effects. The purpose of this review was to describe the presently used dosimetric concepts: 1) the blood dosimetry approach (optimizing the "safety" aspect of the treatment); and 2) lesion-based dosimetry (optimizing the "efficacy" of the treatment) and their respective clinical findings. In addition, a simplified method for performing blood dosimetry and its application towards further enhancement of radioiodine therapies are introduced. Finally, a new concept for potentially determining patient-specific radiation sensitivity using blood dosimetry is introduced.

[Radiation exposure in (90)Y-Zevalin therapy: results of a prospective multicentre trial]. / Strahlenexposition bei der (90)Y-Zevalin-Therapie: Ergebnisse einer prospektiven multizentrischen Studie.

UNLABELLED: AIM of this study was the assessment of the radiation exposure from preparation and application of (90)Y-Zevalin, the measurement of the dose rate at the patient, the exposure of family members as well as the determination of the activity concentration in urine of patients. METHODS: Overall data from 31 therapeutic administrations carried out in four institutions were evaluated. During preparation and application of (90)Y-Zevalin the finger exposures of radiochemists, technicians, and physicians were measured. The dose rate of the patient was measured immediately after radioimmunotherapy. In patients treated in a nuclear medicine therapy unit, urine was collected over a two day period and the corresponding activity was determined. Family members of outpatients were asked to wear a dosimeter over a seven day period. RESULTS: During the preparation we found a maximum skin dose of 6 mSv at the average, and during application of 3 mSv, respectively. After administration of (90)Y the dose rate was 0.4 +/- 0.1 microSv/h at 2 m distance. Urine measurements yielded a cumulated 24 h excretion of 3.9 +/- 1.4% and 4.4 +/- 1.4% within 48 h, respectively, that is equivalent to 43 +/- 18 and 50 +/- 20 MBq of (90)Y, respectively. Family members received a radiation exposure of 40 +/- 14 microSv over seven days. CONCLUSION: During preparation and application of (90)Y-Zevalin appropriate radiation shielding is necessary. For family members as well as nursing staff no additional special radiation protection measures beyond those being common for other nuclear medicine procedures are necessary.

Radioiodine ablation of thyroid remnants after preparation with recombinant human thyrotropin in differentiated thyroid carcinoma: results of an international, randomized, controlled study.

CONTEXT: After surgery for differentiated thyroid carcinoma, many patients are treated with radioiodine to ablate remnant thyroid tissue. This procedure has been performed with the patient in the hypothyroid state to promote endogenous TSH stimulation and is often associated with hypothyroid symptoms and impaired quality of life. OBJECTIVE AND INTERVENTION: This international, randomized, controlled, multicenter trial aimed to compare the efficacy and safety of recombinant human TSH (rhTSH) to prepare euthyroid patients on L-thyroxine therapy (euthyroid group) to ablate remnant thyroid tissue with 3.7 GBq (100 mCi) 131I, compared with that with conventional remnant ablation performed in the hypothyroid state (hypothyroid group). Quality of life was determined at the time of randomization and ablation. After the administration of the 131-I dose, the rate of radiation clearance from blood, thyroid remnant, and whole body was measured. RESULTS: The predefined primary criterion for successful ablation was "no visible uptake in the thyroid bed, or if visible, fractional uptake less than 0.1%" on neck scans performed 8 months after therapy and was satisfied in 100% of patients in both groups. A secondary criterion for ablation, an rhTSH-stimulated serum thyroglobulin concentration less than 2 ng/ml, was fulfilled by 23 of 24 (96%) euthyroid patients and 18 of 21 (86%) hypothyroid patients (P = 0.2341). Quality of life was well preserved in the euthyroid group, compared with the hypothyroid group, as demonstrated by their lower pretreatment scores on the Billewicz scale for hypothyroid signs and symptoms, 27 +/- 7 vs. 18 +/- 4 (P < 0.0001) and their significantly higher Short Form-36 Health Assessment Scale scores in five of eight categories. Euthyroid patients had a statistically significant one third lower radiation dose to the blood, compared with patients in the hypothyroid group. CONCLUSIONS: This study demonstrates comparable remnant ablation rates in patients prepared for 131I remnant ablation with 3.7 GBq by either administering rhTSH or withholding thyroid hormone. rhTSH-prepared patients maintained a higher quality of life and received less radiation exposure to the blood.

[Intrathyroidal iodine concentration after application of non-ionic contrast media with and without prophylactic application of perchlorate]. / Intrathyreoidale Iodkonzentration nach Applikation nichtionischer Kontrastmittel ohne und mit Perchlorat-Gabe.

AIM: This study was designed to show the effect of a nonionic contrast medium (Iomeprol-300; CM) on the intrathyroidal iodine concentration with and without a concomitant medication with perchlorate (1380 mg/d) to block the thyroidal iodine uptake. VOLUNTEERS AND METHODS: Twelve volunteers recieved 100 ml Iomeprol-300 intravenously and the perchlorate prophylaxis mentioned above. Another 12 volunteers got 100 ml Iomeprol-300 only. By means of X-ray-fluorescence-analysis the intrathyroidal iodine concentration was determined in advance as well as 0.2, 1, 3, 5, 7, 24, 48, 72, and 96 hours after the application of the CM. RESULTS, CONCLUSION: The intrathyroidal iodine concentration did not change in the group of volunteers on perchlorate medication. Without perchlorate the intrathyroidal iodine concentration decreased after the application of the CM when it was initially high (722 +/- 66 microg/ml before, 670 +/- 65 microg/ml after CM; p = 0.046) and increased in case of a low initial concentration (327 +/- 40 microg/ml before, 381 +/- 25 microg/ml after CM; p = 0.046). The effect is significant but its magnitude is too small to be harmful for a patient with a healthy thyroid. The oral application of 1.4 g/d perchlorate inhibits the thyroidal iodine uptake and the intrathyroidal iodine concentration is unaffected by the application of a CM.

[Monitoring of 131I incorporation in nuclear medicine personnel by self accomplished measurements]. / 131I-Inkorporationsüberwachung in der Nuklearmedizin durch regelmässige Eigenmessung des Personals.

AIM: The personnel in nuclear medicine therapy wards must be monitored according to German guidelines for incorporations of (131)I. A surveillance with the employees measuring themselves similarly to the autonomous contamination survey using hand-foot-clothing monitors is presented as an alternative to the monitoring according to the official guidelines. METHOD: The employees use a dedicated device to measure themselves every working day. The automatic individual positioning of the device ensures reliable and reproducible results. The thyroid dose is determined from the measured time activity curve. The individual values of depth and mass of the thyroid are taken into account for activity measurement and dose evaluation, respectively. RESULTS: The employees measure themselves regularly and utilize the device to check for activities in the thyroid at an early stage after suspected incorporation. The almost complete surveillance permits a dosimetry with slight uncertainty. The determined thyroid doses of all monitored persons average to 0.35 mSv per month. CONCLUSION: The incorporation surveillance by autonomous monitoring allows a more reliable and more precise dosimetry than the monitoring according to the official guidelines. Despite numerous measurements the practice saves time and money as a result of the automation.

Does an individual estimation of halflife improve the results of radioiodine therapy of Graves' disease?

AIM: The impact of our dosimetry concept on radioiodine therapy success in Graves' disease (GD) was analysed. Three questions arised: Did individual estimation of pretherapeutic halflife improve therapeutic success? Did individual dosimetry result in accurate dose calculation? Did antithyroid medication have a measurable influence on therapeutic success under the prevailing conditions? METHODS: 126 consecutive patients were treated with 200 Gy I-131 in our therapy ward for GD and followed-up six to nine months after therapy. Success quote was assessed using a standardized protocol and treatment was classified as successful when the patient was eu- or hypothyroid, or unsuccessful when he or she presented with a suppressed TSH-level or in hyperthyroid condition after antithyroid medication withdrawal. Antithyroid medication, activity I-131, dose, concentration of fT3 and fT4, specific delivered dose and halflife were put into a multiple regression model to assess their influence on therapeutic success. In order to assess possible factors disturbing the therapeutic outcome, relevant parameters were analyzed using Logit transformation. RESULTS: Out of 126 patients 84 were classified as successfully treated and 42 (33.3%) as failures. A significant influence on the outcome only was found for thyroid mass. However, therapeutic success appeared to be more distinctly determined by the specific delivered dose using an estimated halflife of 5.5 days (Odds: 10.0, p < 0.001). Accurate intratherapeutic dosimetry did not play a significant role to enhance therapeutic success. Neither did antithyroid medication during radioiodine therapy exert any significant impact. CONCLUSIONS: Measurement of individual intratherapeutic halflife as opposed to an estimate using a standard halflife did not provide improved results concerning the target dose. Retrospectively, the therapeutic outcome on the basis of a measured halflife as compared to a standard halflife did not significantly improve. In addition, no influence of antithyroid medication on therapy success was found.

Antithyroid drugs as a factor influencing the outcome of radioiodine therapy in Graves' disease and toxic nodular goitre?

There is controversy over the factors that may influence the outcome of radioiodine therapy for benign thyroid diseases. Antithyroid medication has been claimed to negatively influence the effectiveness of radioiodine therapy in Graves' disease. In a longitudinal study, we assessed the influence of sex, age, antithyroid drugs, target radiation dose, target mass, applied activity, delivered dose, interval between last meal and application, and TSH, FT3 and FT4 levels on the outcome of radioiodine therapy. One hundred and forty-four patients (111 female, 33 male) suffering from Graves' disease (GD) and 563 patients (434 female, 129 male) with toxic nodular goitre (TNG) were entered in the study and followed up until 8 months after therapy. Treatment was defined as successful when the TSH level was found to be normal or elevated. Ninety-eight GD patients and 418 TNG patients were successfully treated. Forward stepwise multiple regression analysis models retained only the target mass in GD and the applied activity in TNG as significantly associated with the outcome of therapy. The predictive value of all variables involved was extremely low in both disease groups. Whereas concomitant antithyroid medication had no influence in GD, it adversely influenced radioiodine therapy of TNG. This effect may be attributed to a radioiodine "steal phenomenon" induced by TSH-stimulated normal thyroid tissue, which causes overestimation of the uptake in toxic nodules.

[Comparison of the effectiveness of two different dosages of levothyroxine-iodide combinations for the therapy of euthyroid diffuse goiter]. / Vergleich der Wirksamkeit zweier verschieden dosierter Levothyroxin-Iodid-Kombinationen in der Therapie der euthyreoten diffusen Struma.

BACKGROUND AND OBJECTIVE: Administration of levothyroxine and/or iodide can effectively reduce the volume of endemic goitre. However, TSH suppression during levothyroxine treatment may increase the number of recurrences through the persistence of intrathyroidal iodine deficiency. With special attention paid to the level of levothyroxine, a comparison was made of two dosages of combined levothyroxine and iodide. PATIENTS AND METHODS: 44 patients with diffuse euthyroid goitre were randomized to two treatment groups. Group A received 100 micrograms levothyroxine + 100 micrograms iodide, group B 75 micrograms levothyroxine + 150 micrograms iodide, all of them for three months. This was followed by three months without the medication. Intrathyroidal iodine concentration was measured at the onset of the study, then three months and six months later. At these same times thyroid volume was measured by ultrasound, as well as urinary iodine and various parameters of thyroid function. RESULTS: Thyroid gland volume was reduced in both groups (group A: -17.3%; group B: -14.8%; p < 0.001). There was no significant difference of intrathyroidal iodine concentration and thyroid volume between both groups. After the treatment period, TSH suppression was more marked in group A, while TSH rise was greater in group B. CONCLUSIONS: Both drug combinations resulted in comparable reduction of thyroid volume, while the intrathyroid concentration of iodine remained unchanged. The smaller rise of TSH after the treatment suggests that the dosage of 75 micrograms levothyroxine + 150 micrograms iodine is to be preferred.

[Is the post-therapeutic dosimetry of patients with short-term hospitalization after 131I therapy sufficiently reliable?]. / Ist die posttherapeutische Dosimetrie bei verkürzter stationärer Verweildauer der Patienten nach 131-I-Therapie ausreichend zuverlässig?

AIM: According to the new recommendations of the Federal German Radiation Protection Committee (SSK) for patient discharge, that were published in April 1997, patients can be discharged after radioiodine therapy with a radiation exposure of less than 1 mSv per year in 2 m distance. The aim of this study was to evaluate whether the measurement of the achieved dose was different 48 hours after application of I-131 and after an interval of one week. The study was planned in order to ensure quality management in the follow-up of the patients. METHOD: In a prospective study 115 patients were followed, that were treated for a benign thyroid disease. The patients were discharged 48 hours after the intake of I-131 after falling short of the exposure limit. All patients were measured at discharge and about 8 days later with the same uptake facility. RESULTS: Because of similar results focal and disseminated forms of benign thyroid diseases could be analysed together. The calculated doses 8 days after the discharge were higher than the values at the time of discharge. The doses were underestimated about 4% with an standard error of 15%. CONCLUSION: The error in early dosimetric measurements is small in comparison to the overall uncertainty in therapy and uptake dosimetry. A valid dosimetry and sufficient quality management can be guaranteed even for an early discharge.