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Background: We provide an update on calcitonin (Ctn) screening for the early detection of medullary thyroid carcinoma (MTC) and present the results of a large single-center analysis evaluating sex-specific cut-off-levels and long-term courses. Methods: A total of 12,984 consecutive adult patients (20.1% male and 79.9% female) with thyroid nodules who had undergone routine Ctn measurement were retrospectively analyzed. Patients with confirmed suspicious Ctn values were referred for surgery. Results: Ctn measurements were elevated in 207 (1.6%) patients, with values below twice the sex-specific reference limit in 82% of these cases. Further clarification was possible in 124/207 cases, of which MTC could be ruled out in 108 cases. Histopathological assessment confirmed MTC in 16/12,984 patients. Conclusions: Our extrapolated MTC prevalence of 0.14% is significantly lower than that described in early international screening studies. The stimulation test can usually be dispensable when using a decision-making concept based on sex-specific basal Ctn cut-off values. Ctn screening is recommended even in patients with very small thyroid nodules. High quality standards in pre-analytics, laboratory measurements, and the interpretation of data must be ensured, as well as close interdisciplinary cooperation between medical disciplines.

Purpose An accurate postoperative assessment is pivotal to inform postoperative 131I treatment in patients with differentiated thyroid cancer (DTC). We developed a predictive model for post-treatment whole-body scintigraphy (PT-WBS) results (as a proxy for persistent disease) by adopting a decision tree model. Methods Age, sex, histology, T stage, N stage, risk classes, remnant estimation, TSH, and Tg were identified as potential predictors and were put into regression algorithm (conditional inference tree, ctree) to develop a risk stratification model for predicting the presence of metastases in PT-WBS. Results The lymph node (N) stage identified a partition of the population into two subgroups (N-positive vs N-negative). Among N-positive patients, a Tg value > 23.3 ng/mL conferred a 83% probability to have metastatic disease compared to those with lower Tg values. Additionally, N-negative patients were further substratified in three subgroups with different risk rates according to their Tg values. The model remained stable and reproducible in the iterative process of cross validation. Conclusions We developed a simple and robust decision tree model able to provide reliable informations on the probability of persistent/metastatic DTC after surgery. These information may guide post-surgery 131I administration and select patients requiring curative rather than adjuvant 131I therapy schedules.

Aims In contrast to all prior AJCC/TNM classifications for differentiated thyroid cancer (DTC) the 8th edition does not take minimal extrathyroidal extension (M-ETE) into consideration for local tumor staging. We therefore aimed to retrospectively assess the specific impact of M-ETE on the outcome of M-ETE patients treated in our clinic. Methods DTC patients with M-ETE and a follow-up time of ≥ 5 years were included and matched with an identical number of patients without M-ETE, but with equal histopathological tumor subtype and size. The frequency of initially metastatic disease among groups was compared using Fisher’s exact test, the recurrence rate by virtue of log-rank test. Fisher’s exact test and multivariate analysis were used to account for the presence of confounding risk factors. Results One hundred sixty patients (80 matching pairs) were eligible. With other confounding risk factors being equal, the prevalence of N1-/M1-disease at initial diagnosis was comparable among groups (M-ETE: 42.5 %; no M-ETE: 32.5 %; p = 0.25). No differences with regard to the recurrence rate were shown. However, M-ETE patients were treated with external beam radiation therapy more often (16.3 % vs. 1.3 %; p = 0.004) and received higher median cumulative activities of 131I (10.0 vs. 8.0 GBq; p Discussion Although having played a pivotal role for local tumor staging of DTC for decades M-ETE did not increase the risk for metastases at initial diagnosis and the recurrence rate in our cohort. Patients with M-ETE had undergone intensified treatment, which entails a possible confounding factor that warrants further investigation in randomized controlled trials.

Background. Differentiated thyroid carcinoma (DTC) is characterized by an excellent prognosis with a 10-year survival rate > 90%. However, when DTC develops in a metastatic form, it has been shown to significantly impact patient survival and quality of life. Although I-131 has been shown to be an effective therapy in patients with metastatic DTC, whether its efficacy after recombinant human TSH (rhTSH) is comparable to endogenous TSH stimulation by thyroid hormone deprivation (THW) is still debated. Our present study was prompted to compare clinical results obtained in metastatic DTC by I-131 administered after rhTSH and THW stimulation protocols, respectively. Methods. A systematic search on PubMed, Web of Science, and Scopus was performed from January to February 2023. Pooled risk ratios with 95% CI were determined for evaluating the initial response after to I-131 therapy after preparation with rhTSH or THW and the disease progression. To track the accumulation of evidence and reduce type I errors because of small data, a cumulative meta-analysis was performed. A sensitivity analysis was also performed to examine the impact of individual studies on overall prevalence results. Results. Ten studies were included with a total of 1929 patients pre-treated with rhTSH (n = 953) and THW (n = 976), respectively. The cumulative data of our systematic review and meta-analysis showed an increase in the risk ratio over the years without any change in favour of a pre-treatment or the other on the effectiveness of I-131 therapy of metastatic DTC. Conclusions. Our data suggest that pretreatment with rhTSH or THW has no significant impact on the effectiveness of I-131 therapy for metastatic DTC. This implies that concerns about the use of one or the other pretreatment should be deferred to clinical evaluations made considering patient characteristics and reduction in side effects.

ZusammenfassungAus fachfremder Sicht wird der Stellenwert der „konventionellen“ Schilddrüsenszintigrafie zur Klärung diverser thyreologischer Fragestellungen international mittlerweile weit niedriger eingeschätzt, als dies dem hierzulande tätigen Nuklearmediziner bewusst ist. Dieser Aufsatz gibt einen Überblick über häufig geäußerte Kritikpunkte an der Schilddrüsenszintigrafie und möchte einiges hierzu klarstellen sowie in berechtigten Fällen fundierte Gegenargumente liefern. In diesem Rahmen wird ein Überblick über die weiterhin bestehenden Indikationen gegeben, es werden aber auch Aspekte angeschnitten, bei denen Verbesserungsbedarf besteht. Abschließend erfolgt eine Aussicht auf zukünftige Perspektiven und Weiterentwicklungen der funktionellen Charakterisierung von thyreoidalem Gewebe.

Background Regarding the longer-term recurrence rate the optimal activity for the remnant thyroid ablation in patients with differentiated thyroid cancer (DTC) is discussed controversially. For the short-term ablation success rate up to 12 months there are already several meta-analyses. In this study we performed the first meta-analysis regarding the longer-term recurrence rate after radioactive 131-I administration. Methods We conducted an electronic search using PubMed/MEDLINE, EMBASE and the Cochrane Library. All randomized controlled trials (RCTs) assessed the recurrence rate after radioactive iodine ablation in patients with DTC, with a follow-up of at least two years were selected. Statistics were performed by using Review Manager version 5.3 and Stata software. Results Four RCTs were included in the study, involving 1501 patients. There was no indication for heterogeneity (I2 = 0%) and publication bias. The recurrence rate among patients who had a low dose 131-iodine ablation was not higher than for a high dose activity (odds ratio (OR) 0.93 [95% confidence interval (CI) 0.53–1.63]; P = 0.79). The mean follow-up time was between 4.25 and 10 years. The subgroup analysis regarding the TSH stimulated thyroglobulin values ( Conclusions For the first time we showed that the longer-term, at least 2-year follow-up, recurrence rate among patients who had 131-iodine ablation with 1.1 GBq was not higher than with 3.7 GBq.

Radioiodine-131 treatment has been a well-established therapy for benign thyroid diseases for more than 75 years. However, the physiological reasons of the so-called stunning phenomenon, defined as a reduced radioiodine uptake after previous diagnostic radioiodine administration, are still discussed controversially. In a recent study, a significant dependence of thyroid stunning on the pre-therapeutically administered radiation dose could be demonstrated in patients with goiter and multifocal autonomous nodules. A release of thyroid hormones to the blood due to radiation-induced destruction of thyroid follicles leading to a temporarily reduced cell metabolism was postulated as possible reason for this indication-specific stunning effect. Therefore, the aim of this study was to develop dose-dependent correction factors to account for stunning and thereby improve precision of radioiodine treatment in these indications. A retrospective analysis of 313 patients (135 with goiter and 178 with multifocal autonomous nodules), who underwent radioiodine uptake testing and radioiodine treatment, was performed. The previously determined indication-specific values for stunning of 8.2% per Gray in patients with multifocal autonomous nodules and 21% per Gray in patients with goiter were used to modify the Marinelli equation by the calculation of correction factors for hyperfunctioning radiation-induced stunning (CHRIS). Subsequently, the calculation of the required activity of radioiodine-131 to obtain an intra-therapeutic target dose of 150 Gy was re-evaluated in all patients. Furthermore, a calculation of the hypothetically received target dose by using the CHRIS-calculated values was performed and compared with the received target doses. After integrating the previously obtained results for stunning, CHRIS-modified Marinelli equations could be developed for goiter and multifocal autonomous nodules. For patients with goiter, the mean value of administered doses calculated with CHRIS was 149 Gy and did not differ from the calculation with the conventional Marinelli equation of 152 Gy with statistical significance (p = 0.60). However, the statistical comparison revealed a highly significant improvement (p

Purpose: (i) To examine the criterion taller-than-wide (TTW) for the sonographic assessment of thyroid nodules in areas of iodine deficiency in terms of frequency, anatomical distribution within the thyroid gland and risk of malignancy. (ii) To develop a model for nodule growth in the thyroid gland. Methods: German multicenter study consisting of two parts. In the prospective part, thyroid nodules were sonographically measured in all three dimensions, location within the thyroid gland and contact to a protrusion-like formation (horn) in the dorsal position of thyroid gland was noted. In addition, further sonographic features such as the composition, echogenity, margins and calcifications were investigated. All nodules from the prospective part were assessed for malignancy as part of clinical routine at the decision of the treating physician adhering to institutionally based algorithms. In the retrospective part, only nodules with fine needle aspiration and/or histology were included. The risk of malignancy in TTW nodules was determined by correlating them with cyotological and histological results. Results: Prospective part: out of 441 consecutively evaluated thyroid nodules, 6 were found to be malignant (1.4%, 95% CI 0.6–2.7%). Among the 74 TTW nodules (17%), 1 was malignant (1%, 95% CI 0–4%). TTW nodules were more often located in the dorsal half of the thyroid than non-TTW nodules (factor 2.3, p = 0.01, 95% CI 2.1–2.5) and more often located in close proximity to a horn than non-TTW nodules (factor 3.0, p = 0.01, 95% CI 2.4–3.8). Retrospective part: out of 1315 histologically and/or cytologically confirmed thyroid nodules, 163 TTW nodules were retrieved and retrospectively analyzed. A TTW nodule was 1.7 times more often benign when it was dorsal (95% CI 1.1–2.5) and 2.5 times more often benign when it was associated with a horn (95% CI 1.2–5.3). The overall probability of malignancy for TTW nodules was 38% (95% CI 30–46%) in this highly preselected patient group. Conclusion: TTW nodules are common in iodine deficient areas. They are often located in the dorsal half of the thyroid gland and are frequently associated with a dorsal protrusion-like formation (horn) of the thyroid. Obviously, the shape of benign nodules follows distinct anatomical preconditions within the thyroid gland. The frequency of TTW nodules and their predominant benignity can be explained by a pole concept of goiter growth. The difference between the low malignancy risk of TTW nodules found on a prospective basis and the high risk found retrospectively may be the result of a positive preselection in the latter.

To investigate the interobserver agreement (IA) and the impact of consensus reading using four risk stratification systems for thyroid nodules (TN). Four experienced specialists independently rated US images of 80 TN according to the Kwak-TIRADS, EU-TIRADS, ACR TI-RADS, and ATA Guidelines. The cases were randomly extracted from a prospectively acquired database (n > 1500 TN). The observers were blinded to clinical data. This study was divided into two sessions (S1 and S2) with 40 image sets each. After every session, a consensus reading was carried out (C1, C2). Subsequently, the effect of C1 was tested in S2 with 40 new cases followed by C2. Fleiss’ kappa (κ) was calculated for S1 and S2 to estimate the IA and learning curves. The results of C1 and C2 were used as reference for diagnostic accuracy calculations. IA significantly increased (p

The aim of this study was to investigate in a longitudinal approach whether levothyroxine (LT4) substitution has a different impact on quality of life (QoL) and thyroid related QoL in younger (60 years) with elevated thyroid-stimulating hormone (TSH) concentrations. The study included male and female patients with newly diagnosed, untreated subclinical hypothyroidism defined by TSH>8 mU/l. Patients were recruited throughout Germany from 2013–2016 and evaluated by clinical assessment, blood sampling and questionnaires for health related QoL and thyroid-disease thyroid-related QoL (ThyPRO) at time of diagnosis and six months after initiation of LT4 treatment. We found significantly lower QoL in both young and old patients with subclinical hypothyroidism compared to age-matched healthy individuals. Higher scores on follow-up were found in all patients irrespective of age, indicating better QoL on LT4 therapy. Analysis of the ThyPRO questionnaire showed that old patients experienced less Emotional Susceptibility, Tiredness, and Impaired Day Life on LT4, while young patients reported less Cognitive Complaints, Emotional Susceptibility, and Impaired Day Life compared to baseline assessment. Hypothyroidism with TSH concentrations>8 mU/l is associated with impairment in general and ThyPRO QoL in young and old age. Older patients benefited from LT4 therapy and remarkably show similar degree of improvement as younger patients, albeit with some thematic variation in ThyPRO QoL. Our data confirm current recommendations on initiation of LT4 substitution and suggest that this should not be withheld in elderly with TSH concentration above 8–10 mU/l.

to evaluate the time trend of epidemiology of follicular cell derived thyroid cancer (TC) based on data from a well documented cancer registry.Population based data on TC from Lower Franconia (LF), Germany, within 1981 and 2015 were analysed to estimate the regional epidemiology of TC. The incidence was assessed in 5-year-intervals for gender, histology, and tumor stage.Incidence of TC solely attributable to papillary TC (PTC) doubled mainly in T1- and T2-stages within the evaluation period from 4.5 to 8.7/100.000/y in females and 1.7 to 4.1/100.000/y in males. There was no significant change of follicular TC (FTC), whereas anaplastic TC (ATC) decreased in the same interval. The number of lymph-node metastases and T3-cases increased, while the frequency of T4-stage and distant metastases decreased. Increased incidences of T1- and T2-stages suggest an over-diagnosis. In contrast, increasing number of tumors at T3-stage and with lymph node involvement contradict the over-diagnosis as the only reason for rising incidence. Declining of T4-stages in spite of increasing of T3-stages and N1-cases indicates the value of timely detection and treatment of TC. In accordance, reduced incidence of advanced cancers with M1-stage and ATC cases promote our current management of TC.Timely diagnosis and adequate risk-adopted treatment of thyroid cancer reduce the frequency of high-risk cases with distant metastases and the possible protracted dedifferentiation of TC to anaplastic features. Our analyses support the management algorithm in thyroid cancer according to the recent guidelines of German Nuclear Medicine Society.ZIEL: Evaluierung des Trends der Epidemiologie von Schilddrüsenkrebs (TC) in Unterfranken (UF).Populationsbasierte Daten aus Unterfranken aus den Jahren 1981 bis 2015 wurden analysiert und die Änderung der Inzidenz des TC ermittelt. Die Inzidenz wurde in 5-Jahres-Intervallen in Bezug auf Geschlecht, Histologie, und Tumorstadium berechnet.Die TC-Inzidenz verdoppelte sich im Auswertungszeitraum, bei Frauen von 4,5 auf 8,7/100.000/J und von 1,7 auf 4,1/100.000/J bei Männern, was überwiegend den papillären Schilddrüsenkarzinomen (PTC) in T1- und T2-Stadien zuzuschreiben ist. Es gab keine signifikante Änderung beim follikulären TC (FTC), während die Häufigkeit des anaplastische TC (ATC) abnahm. Die Anzahl der Lymphknotenmetastasen und T3-Fälle stieg, während die Frequenz der T4-Fälle und der Fernmetastasen in diesem Intervall abnahm. Eine erhöhte Inzidenz von Karzinomen in T1- und T2-Stadien ließe sich durch Überdiagnostik erklären. Im Gegensatz dazu sprechen die Zunahme der Inzidenz von Tumoren in T3- und N1-Stadien gegen eine Überdiagnose als einzigen Grund für den Anstieg. Die abnehmende Zahl von Patienten mit T4-Stadium bei gleichzeitigem Anstieg der Fälle im T3- und N1-Stadium sprechen vielmehr für eine rechtzeitige Diagnose von Schilddrüsenkarzinomen. Die abnehmende Inzidenz der weit fortgeschnittenen Fälle mit Fernmetastasen und mit ATC im gleichen Zeitraum bestätigen das bei uns verfolgte Konzept.Die rechtzeitige Diagnose und adäquate risikoadaptierte Behandlung des Schilddrüsenkarzinoms im Frühstadium reduziert die Häufigkeit von Hochrisiko-Fällen mit Fernmetastasen und verhindert die mögliche Entdifferenzierung vom DTC zu anaplastischen Tumoren. Unsere Analysen bestätigen das therapeutische Management von Schilddrüsenkrebs gemäß Leitlinien der Deutschen Gesellschaft für Nuklearmedizin.

Both, ultrasonography but also radionuclide imaging using [99mTc]Pertechnetate or radioactive iodine isotopes are essential tools used during the diagnostic workup of hyperthyroidism with or without structural alterations of the thyroid. Colour duplex sonography and ultrasound elastography may add important information in order to find the cause of the hormone excess. During the last years, also hybrid imaging using SPECT/-(CT) or PET-based methods, such as [124]Iodine-PET/CT or [124]Iodine-PET/ultrasound also have nodularbeen increasingly used and especially play a role in the context of localizing ectopic thyroid tissue or in multinodular goiter. Recently also promising data has been published on the use of [99mTc]MIBI imaging in amiodarone induced hyperthyroidism.

Objective The usefulness of routine calcitonin measurement for early detection of medullary thyroid carcinoma (MTC) in patients with nodular thyroid disease (NTD) has been investigated in various studies. Recently, a Cochrane review has been published on this issue, but a meta-analysis is lacking yet. Therefore, we performed this meta-analysis. Methods We performed an electronic search using PubMed/Medline, Embase and the Cochrane Library. Studies assessing the diagnostic accuracy of routine calcitonin measurement for detecting MTC in patients with NDT were selected. Statistics were performed by using Stata software, risk of bias was assessed using Review Manager version 5.3. Results Seventeen studies, involving 74,407 patients were included in the study. Meta-analysis, using the bivariate random effects model and the hierarchical summary receiver operating characteristic (HSROC) curve revealed the following pooled estimates: sensitivity 0.99 (95% CI, 0.81–1.00), specificity 0.99 (95% CI, 0.97–0.99), positive likelihood ratio (L+) 72.4 (95% CI, 32.3–162.1), and negative likelihood ratio (L−) 0.01 (95% CI, 0.00–0.23). Meta-regression analysis showed that the threshold of basal calcitonin is an independent factor, but in particular performing stimulation test is not an independent factor. Conclusions We showed that routine basal serum calcitonin measurement in the management of patients with thyroid nodules is valuable for the detection of MTC. However, the published cut-off values should be considered and, if applicable, the patients monitored in a wait-and-see strategy by experienced physicians to avoid overtreatment.

Objective: Thyroglobulin (Tg) is an important tumor marker for therapy control and follow-up of differentiated thyroid carcinoma (DTC). Over the past decade, assays for highly sensitive Tg measurement have become increasingly established. We evaluated a newly developed high-sensitive Tg assay running on an automated platform (LIAISON® Tg II Gen assay, DiaSorin), with a limit of quantification of 0.10 ng/ml. Design and Methods: Tg values of 166 sera from subjects without thyroid diseases and of more than 500 sera of well-defined DTC patients were determined with the new LIAISON® Tg II Gen assay and compared with two established assays (Elecsys® Tg II/Roche, and Medizym® Tg REM/Medipan). Results: Tg reference values from healthy subjects were up to 37.93 ng/ml (women) resp. 24.59 ng/ml (men) with the LIAISON® Tg II Gen assay. Tg values showed good correlations in healthy subjects and patients with active tumorous disease. In contrast, Tg values in the very low range from cured thyroidectomized patients were poorly comparable between the three assays, while clinical differences between the cohorts were correctly reflected by all assays. Conclusions: With the new LIAISON® Tg II Gen assay, another automated assay standardized against the first International Reference Preparation CRM-457 for highly sensitive measurement of Tg values is available. OA Förderung 2021

Due to the widespread use of ultrasound, small thyroid nodules (TNs) &le, 10 mm are common findings. Standardized approaches for the risk stratification of TNs with Thyroid Imaging Reporting and Data Systems (TIRADS) were evaluated for the clinical routine. With TIRADS, the risk of malignancy in TNs is calculated by scoring the number or combination of suspicious ultrasound features, leading to recommendations for further diagnostic steps. However, there are only scarce data on the performance of TIRADS for small TNs. The aim was to compare three different TIRADS for risk stratification of small TNs in routine clinical practice. We conducted a retrospective cohort analysis of TNs &le, 10 mm and their available histology. Nodules were classified according to three different TIRADS. In the study, 140 patients (n = 113 female) with 145 thyroid nodules (n = 76 malignant) were included. Most of the malignant nodules were papillary carcinoma (97%), and the remaining 3% were medullary carcinoma. For all tested TIRADS, the prevalence of malignancy rose with increasing category levels. The highest negative predictive value was found for ACR TI-RADS and the highest positive predictive value for Kwak-TIRADS. All tested variants of TIRADS showed comparable diagnostic performance for the risk stratification of small TNs. TIRADS seems to be a promising tool to reliably assess the risk of malignancy of small TNs.

Thyroid nodules are a common finding, especially in iodine-deficient regions. Ultrasonographic scoring systems such as the Thyroid Imaging Reporting and Data System (TIRADS) are helpful in differentiating between benign and malignant thyroid nodules by offering a risk stratification model. Depending on the constellation or number of suspicious ultrasound features, a fine-needle biopsy is recommended. However, none of the previous TIRADS publications considered the functional status of the nodules. Hyperfunctioning thyroid nodules (HTNs) were presumed to exclude malignancy with a very high negative predictive value. Particularly in regions where the iodine supply is low, most HTNs are seen in patients with normal thyroid-stimulating hormone levels. Therefore, thyroid scintigraphy is essential for the detection of HTNs. We investigated whether TIRADS identifies HTNs as nonsuspicious. Methods: We evaluated 615 HTNs (23.2 ± 10.0 mm in maximum diameter in 582 patients ([442 women, 57.7 ± 13.2 y old, and 140 men, 60.1 ± 12.7 y old) detected by 99mTc-pertechnetate or 123I scintigraphy. Before evaluating the scintigraphic appearance, all nodules were analyzed prospectively with sonography, using the TIRADS model referenced in Kwak et al., wherein fine-needle biopsy is recommended for TIRADS 4A or higher. We also investigated 2 subgroups, 42 nodules with available histology and 117 patients with subclinical or overt hyperthyroidism. Results: Whereas 15.9% of the nodules were classified as TIRADS 3 or lower and less than 0.1% as TIRADS 5, most of the nodules were classified as TIRADS 4A (29.3%), 4B (29.3%), or 4C (24.9%). Altogether, more than 80% of the autonomous thyroid nodules were classified as TIRADS 4A or higher, a grade that would result in a recommendation of fine-needle biopsy. Focusing on those 117 HTNs that were already associated with hyperthyroid laboratory values, the rates were similar: 81.2% were categorized as TIRADS 4A or higher (4A, 33.3%; 4B, 29.9%; 4C,17.1%; 5, 0.9%). In the subgroup of patients who underwent thyroid surgery, all nodules were benign, confirming the known negative predictive value of HTNs with regard to malignancy exclusion. Conclusion: Integration of thyroid scintigraphy into the TIRADS model is essential to prevent unnecessary fine-needle biopsy and thyroid surgery.

Calcitonin (hCt) ist ein vergleichsweise anspruchsvoller Parameter – sowohl hinsichtlich der Probenbehandlung als auch der Interpretation der Laborergebnisse sowie der hieraus zu ziehenden Konsequenzen. Hinsichtlich der Referenzbereiche sollten geschlechtsspezifische Unterschiede berucksichtigt werden. Die Aussagekraft des Kalzium-Stimulationstests zur Abklarung nur masig erhohter hCt-Basalwerte ist derzeit umstritten; hier besteht noch weiterer Bedarf zur Optimierung bzw. Standardisierung der Durchfuhrung und Interpretation der Ergebnisse. Sofern erwogen wird, hCt im Rahmen eines Screenings bei nodularem Schilddrusenbefund oder als Tumormarker in der Verlaufskontrolle behandelter medullarer Schilddrusenkarzinom-Patienten zu bestimmen, mussen einige Rahmenbedingungen sichergestellt sein. Hierzu gehoren insbesondere: optimale praanalytische und stabile laborchemische Bedingungen, Etablierung kontrollierter geschlechtsspezifischer Interventionsschwellenwerte, ein Recall-System fur Patienten mit zunachst kontrollbedurftigen Werten, die Verfugbarkeit von validierten Stimulationstests im Falle fraglich pathologischer basaler hCt-Werte, Kenntnis moglicher Einflussparameter auf die Messwerte, eigene Expertise hinsichtlich der Besonderheiten des medullaren Schilddrusenkarzinoms (MTC) und die enge interdisziplinare Kooperation zwischen Nuklearmedizin, Endokrinologie, Chirurgie und Pathologie.

Radioiodine therapy is a matter of controversy because different opinions exist about its use for differentiated thyroid carcinoma. The following article sheds light on the different opinions and explains why we advocate the use of radioiodine therapy in more than only high-risk patients. In comparison to other malignancies, differentiated thyroid carcinoma has a different tumor biology due to its usually slow growth pattern. Radioiodine therapy was first used about 75 y ago and provided cure at a time when prospective randomized controlled trials had yet to be developed. Large patient cohorts and usually at least a decade of clinical follow-up are needed to demonstrate a benefit from radioiodine therapy. Thus, especially in low-risk patients, many factors define an individual treatment decision, including tumor stage, extent of surgery, tumor biology, clinical and imaging data, life expectancy, and patient preferences.

Background: The aim of this study was to evaluate whether [18F]-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is useful in the further characterization of sonographically suspicious and scintigraphically hypofunctional thyroid nodules. Methods: 65 patients with a sonographically suspicious thyroid nodules that were hypofunctional on 99m-Tc-pertechnetate scintigraphy (diameter > 1 cm) were retrospectively analyzed. All patients underwent evaluation with FDG-PET/CT. Thyroid nodules were sonographically categorized by TIRADS criteria. FDG uptake in the thyroid nodules was visually compared with the remainder of the thyroid tissue and categorized as pathological or non-pathological. In cases of pathologically increased uptake, maximum standardized uptake value (SUVmax) of the suspicious nodule and the perinodular thyroid tissue were determined. Depending on the results of the FDG-PET/CT, patients underwent thyroid surgery (pathological FDG uptake) or follow-up examinations (...

SummaryAim: Several studies described the ultrasound based real-time elastography (USE) having a high sensitivity, specificity and negative predictive value in the diagnosis of suspicious thyroid nodules. Recently published studies called these results into question. Until now the usefulness of USE in the diagnosis of scintigraphically hyperfunctional thyroid nodules is not examined. Patients, methods: This study included 135 hyperfunctional thyroid nodules of 102 consecutive patients. The following attributes of the nodules were analyzed: stiffness with the USE using scores of Rago or Asteria and ultrasound criteria using TIRADS. Results: 94 of the examined thyroid nodules (70%) were rated as hard (suspicious for malignancy) and 41 nodules (30%) as soft (not suspicious) with a specificity of 30%. The scoring systems of Rago and Asteria showed no sigificant difference. Applying the TIRADS criteria 44 nodules (33%) have a higher risk for malignancy (33 nodules TIRADS 4a, 11 nodules TIRADS 4b). Combining USE and TIRADS 32 nodules (24%) are categorized as suspicious (intersection of hard nodules that are categorized as TIRADS 4a or 4b). Conclusion: Ultrasound based real-time elastography cannot identify scintigraphically hyperfunctional thyroid nodules as benign nodules reliably. Its accuracy in the assessment of at least “hot” thyroid nodules is to be questioned.

Background: An association between smoking and the risk of goitre is reported in some, but not all studies. We investigated the association between smoking, goitre and iodine intake, with respect to different risk factors in 483 healthy men in Germany. Methods: A total of 483 healthy male employees of 4 institutions in Essen in Western part of Germany, aged between 17 and 68 years (43.1 ± 9.6 y) were examined by ultrasound of the neck to determine the thyroid volume between April 2001 and April 2002. Information on age, BMI, smoking, daily use of iodized salt, and familial history of thyroid disorders were assessed by standardized questionnaires. Logistic regression analysis was performed to adjust for smoking, age, iodine status and familial history of goitre. Results: The overall prevalence of goitre was 25.7%. Median thyroid volume among smokers, (23.4 ± 10.1 ml), was higher (p

This study evaluated the impact of 68Ga-DOTATOC PET/CT in detecting recurrence or metastases in differentiated thyroid carcinoma (DTC) patients with elevated serum thyroglobulin and both negative radioiodine imaging and negative 18F-FDG PET/CT. Methods:68Ga-DOTATOC PET/CT (CT without contrast, low-dose) was performed on average 6 wk after negative 18F-FDG PET/CT (CT contrast-enhanced, full-dose) in 15 consecutive radioiodine-negative DTC patients with elevated and rising thyroglobulin. Visual assessment of 68Ga-DOTATOC PET/CT images used a 4-point scale for classification of lesions (0, no pathologic findings; 1, benign; 2, equivocal; 3, malignant). PET findings were correlated with the histologic subtype of tumor, levels of serum thyroglobulin, and morphologic findings on full-dose CT and neck ultrasound. Histology or clinical and imaging follow-up served as a reference standard. Analysis was performed on a patient and lesion basis. Results:68Ga-DOTATOC PET/CT was true-positive in 5 patients (10 tumor lesions) and was false-positive in 1 patient. The rate of positive 68Ga-DOTATOC PET/CT was significantly higher in poorly differentiated/oxyphilic carcinomas (4/4 patients) than in papillary (1/5) or follicular (0/6) tumors. Thyroglobulin levels tended to be higher in patients with tumor localization on 68Ga-DOTATOC PET/CT, but differences were not significant. In 2 of 5 patients with true-positive findings on 68Ga-DOTATOC PET/CT, CT alone but not ultrasound identified 2 of 10 tumor lesions, but in both patients 68Ga-DOTATOC-PET/CT revealed further tumor lesions not detected on CT alone. Conclusion:68Ga-DOTATOC PET/CT should be considered in the case of negative 18F-FDG PET/CT in radioiodine-negative DTC patients with elevated and rising thyroglobulin. Imaging with 68Ga-DOTATOC appears promising especially in poorly differentiated and oxyphilic subtypes of DTC.

Item does not contain fulltext BACKGROUND: Tumor marker doubling time (DT) has been proposed as a prognostic marker for various types of cancer. The present study analyzed the DT of the thyroid-specific tumor marker thyroglobulin (Tg), focusing on patients with progressive differentiated thyroid cancer (DTC). METHODS: A total of 144 Tg courses of 99 patients with progressive or recurrent DTC were included (median observation period 19 months, 3-11 Tg measurements per course) in this retrospective study. The distribution of Tg-DT was determined for both a highly sensitive assay (functional working range 0.03-3 ng/mL) and a routine assay. Tg-DT and other prognostic markers were used to perform uni- and multivariate statistical analyses for survival predictors. RESULTS: The median Tg-DT was 212 days (95% percentile: 49-961 days). No significant differences were observed between DT derived from Tg values in the very low range using a highly sensitive assay and DT calculated from Tg values measured by a conventional Tg assay. Multivariate analysis yielded no simple correlation between Tg-DT and survival rate, but the mortality risk of patients with a Tg-DT 14 months. Highly significant differences on survival rates were only observed in patients with a high tumor load (Tg >100 ng/mL). CONCLUSIONS: Tg-DT alone is not an independent survival predictor in all patients with progressive DTC; however, analyzing only patients with a high tumor load, we found highly significant differences in survival rates.

Background: To evaluate the predictive factors of goitre prevalence in females. Methods: In a questionnaire-based survey, data from 370 female employees aged between from 4 institutions in western part of Germany was collected between April 2001 and April 2002 and the association between parity and simple goitre was examined with respect to age, daily use of iodized salt, contraceptives, the history of goitre in the first degree relatives and smoking. Ultrasound of the neck was performed in all cases to determine the thyroid volume. Logistic regression analyses were performed to adjust for age, iodine status, parity, contraceptives, familial history of goitre and smoking. Results: The overall prevalence of goitre was (80/370) 21.6%. Median thyroid volume Goitre was present in 44 out of 140 parous (31.4%) vs. 34/220 (15.5%) in nulliparous (odds ratio: 2.5; p

Summary Context In patients with differentiated thyroid carcinoma (DTC) who, after thyroidectomy, are to receive radioiodine therapy or diagnostics, a strong TSH stimulus is necessary. Traditionally, this is induced by thyroid hormone withdrawal (THW) over a period of 4–5 weeks; alternatively thyroid hormone replacement therapy is continued and recombinant human thyrotropin (rhTSH) is administered. During the hypothyroid state due to THW, patients often report mood disturbances and physical complaints but also an impairment of performance during attention demanding tasks. Objective Based on physiological, self-report and performance test data collected from various studies, we proposed the hypothesis that thyroidectomized DTC patients perform significantly worse in cognitive-motor functions that are relevant for driving when in the THW-induced hypothyroid state compared to when thyroid hormone replacement therapy is continued and rhTSH is administered. Methods We compared 41 DTC patients (age 42.3 (9.4) years; 80.5% female) after 4 weeks THW with 41 DTC patients after the application of rhTSH, pairwise matched according to age, gender and educational level, with respect to performance in 4 core tests of the Act-React-Testsystem ART-90, a validated test battery for examining fitness to drive. Results Contrary to our expectations, no statistically relevant impairment of performance could be confirmed in the THW group in comparison to the rhTSH group for any variable (at adjusted α). At most there is a tendency in the THW group for slowed reaction times in simple-choice reaction tasks; the (standardized) difference to the rhTSH group is however small (d′ = 0.31). Furthermore, large effects due to THW, as they are suggested by several studies, could be excluded.

Purpose Advanced tumour stage and initial metastases are associated with reduced general and tumour-free survival in patients with differentiated thyroid carcinoma. Optimal initial therapy is mandatory for a positive patient outcome, but can only be performed if all non-iodine-avid tumour lesions are known before planning treatment. We analysed the benefit of 18F-FDG PET/CT at initial diagnosis in patients with high-risk differentiated thyroid carcinoma and determined whether the 18F-FDG PET/CT results led to a deviation from the standard procedure, which consists of two consecutive radioiodine treatments with thyroid hormone suppression in between and no additional imaging, with individual patient management.

Die Radioiodtherapie des differenzierten Schilddrusenkarzinoms hat eine 70-jahrige Tradition. Sie wird sehr gut toleriert, ist nebenwirkungsarm und tragt einen substanziellen Anteil zur guten Prognose der Erkrankung bei. An den Grundprinzipien der Therapie hat sich nichts geandert. Voraussetzung fur den Erfolg ist die gute Aufnahme des Iods in die Schilddrusenkarzinomzelle und die moglichst lange Retention. In den letzten Jahren sind verschiedene Innovationen zu verzeichnen. Die fur die Iodaufnahme fur erforderlich gehaltene TSH-Stimulation ist seit einigen Jahren auch mittels rhTSH-Injektionen moglich, wodurch die durch den Schilddrusenhormonentzug bedingten hypothyreoten Beschwerden vermieden werden konnen. Eine zuverlassige und vorhersagbar positive (im Sinne einer hoheren Lasionsstrahlendosis) Beeinflussung der Iodkinetik ist derzeit jedoch weiterhin nicht bekannt. Die Gabe von Li + konnte ebenso hilfreich sein wie andere Modalitaten zur Beeinflussung der Iodkinetik, die von der Behandlung gutartiger Schilddrusenerkrankungen her bekannt sind. Die Identifizierung von Patienten, bei denen eine kurative Radioiodtherapie nicht zu erwarten ist, wird durch die Dosimetrie mit 124 I – PET/CT moglich und daruber hinaus mittels der pratherapeutischen Dosimetrie auch die individuelle Festsetzung der 131 I-Therapieaktivitat. Durch die Einfuhrung der SPECT/CT steht eine Gammakamera-basierte Schnittbilddiagnostik mit anatomischer Korrelation auch mit dem Therapienuklid 131 I zur Verfugung, wodurch die Aussagekraft der Post-Therapie-Szintigrafie gesteigert wird.

BACKGROUND Calcitonin (CT) is a sensitive marker for evaluation of medullary thyroid cancer (MTC). However, CT measurement can vary with assay- and nonassay-dependent factors, and procalcitonin (PCT) measurement has been proposed for evaluating questionable increases in CT. METHODS We tested 2 fully automated CT assays (Immulite [IL] and Liaison [LIA]) and 1 nonautomated CT assay (IRMA, Medipan) and compared these results with PCT (Brahms Kryptor). We evaluated preanalytical conditions and PCT cross-reactivity in sera of 437 patients with clinical conditions associated with hypercalcitoninemia. Additionally, we determined the true “nil” CT concentration in 60 thyroidectomized patients and defined CT cutoff concentrations for pentagastrin stimulation testing in 13 chronic kidney disease (CKD) patients and 10 MTC patients. RESULTS Markedly decreased CT concentrations were found after storage of sera for >2 h at room temperature and >6 h at 4 °C. Cutoff concentrations for basal and stimulated CT were disease and assay dependent. Proton pump inhibitor therapy was the most frequent reason for increased CT. PCT concentrations were higher in patients with MTC than in patients with CKD without infections (P < 0.001). Whereas IL and LIA demonstrated comparable analytical quality, the IRMA gave increased CT concentrations in nil sera and showed cross-reactivity with PCT in patients with concomitant bacterial infection. CONCLUSIONS IL, LIA, and IRMA detected increased CT concentrations in non-MTC patients and discriminated MTC from CKD patients in pentagastrin tests. PCT assessment may be helpful in the diagnostic work-up of increased CT concentrations in questionable clinical circumstances.

SummaryObjective: Optimization of a specially developed automatic microaspirator for fine-needle aspiration of suspicious thyroid nodules. Patients, method: In a preliminary test biopsy effectiveness was evaluated in 20 native resected thyroid glands in vitro with both a Cameco® gun and a specially designed microaspirator respectively. In addition in both techniques two different needles (21-G and 27-G) were used to evaluate the influence of these two cannula. Subsequently, 103 thyroid nodules were biopsied in vivo and compared the results with a preliminary series of the same physician. In the workup and evaluation of the cytology the ThinPrep® technology was used. Results: In vitro the automatic microaspirator was superior to Cameco gun in both when using the 21-Gauge and the 27-Gauge needle. In terms of needle sizes a statistically significant difference at the 95% confidence level was evident for both comparisons in favor of 21-gauge needle. In vivo, 91% of punctures with the microaspirator were usable, while in the pre-series only 84% were usable (p > 0.05). Conclusion: The automatic microaspirator is superior to the manual aspiration. Moreover, under sonographic control it is more convenient, to biopsy even very small nodules and lesiosn (down to 4 mm in diameter)

Ziel: In den vergangenen Jahren wurden von verschiedenen Fachgesellschaften Leitlinien zur diagnostischen Abklarung von Schilddrusenknoten publiziert, in denen die Indikation zur Szintigraphie beschrankt wird auf Patienten mit subnormalen TSH-Werten. Es wird kontrovers gesehen, ob diese Empfehlungen auf Deutschland ubertragen werden sollten, u. a. wegen der hierzulande geringeren Iodversorgung und des dadurch bedingten hoheren Anteils fokaler Autonomien, die nicht mit messbarer Dysfunktion einhergehen. Da hierzu kaum belastbare Daten publiziert sind, wollten wir multizentrisch das Spektrum szintigraphisch „heiser“ und „warmer“ Knoten unter aktuellen epidemiologischen Bedingungen analysieren. Patienten, Methoden: In 10 nuklearmedizinischen Praxen in unterschiedlichen Regionen Deutschlands werteten wir die diagnostischen Daten von 514 Patienten aus, bei denen sich mittels 99mTc-Pertechnetatszintigraphie eindeutig mehranreichernde Knoten (fokale Mehranreicherungen im Vergleich zum perinodularen Gewebe mit sonographischem Knotenkorrelat ≥1 cm) nachweisen liesen. Um den Selektionsbias zu minimieren, wurden die Erhebungen nicht in Kliniken durchgefuhrt. Zu den erfassten Parametern gehorten die Schilddrusenhormonwerte, der globale 99mTc-Uptake (TcTU), die Grose der einzelnen Knoten und das autonome Gesamtknotenvolumen (Vaut). Ergebnisse: Lediglich bei 20% der Patienten mit „heisen“ Knoten lagen die TSH-Werte im subnormalen Bereich (

Thyroglobulin and calcitonin are established humoral tumor markers for therapy monitoring and follow up of thyroid cancer of follicular origin or medullary thyroid cancer, respectively. In comparison to many other tumor markers these analytes offer a high diagnostic specificity, which increases with the radicalness of thyroid ablation. Over the last years, assays with rising functional sensitivity became commercially available, being however a challenge in respect to laboratory performance, quality assurance and medical judgement in the „ultrasensitive” range of detectable concentrations. Anyway, hTg and hCT must be considered to be ambitious laboratory parameters. The results considerably depend on various in vivo and in vitro influences, and even under constant conditions, different assays may not necessarily produce identical results. hCt assays that measure the monomer (mature) calcitonin form have the advantage of an enhancement of the diagnostic specificity. Apart from follow up investigations in treated MTC patients, a couple of medical societies assume hCt measurement to be justified in the presence of a thyroid nodule. In contrast, guidelines do not recommend hTg measurement as a routine procedure for the assessment of the malignancy of thyroid nodules. However, hTg measurement may have an indication in differential diagnosis of connatal hypothyroidism, in assumed thyrotoxicosis factitia and as a marker of destructive thyroidal disease like subacute or amiodarone-induced thyroiditis.

Radioiodine therapy of benign thyroid diseases (focal = [toxic adenoma], multifocal, disseminated autonomy, Grave's disease or clinical relevant goitre) needs to be and can be performed individually for each patient. Most frequently a radioiodine test is performed applying a small activity of iodine-131 ( 131 I). The paper discusses some protocols for pre- or posttherapeutic dosimetry and discusses their advantages and disadvantages. All are based on the volumetry of the target tissue as well as the radioiodine kinetics in the target volume what may be represented by maximum uptake and half life of iodine retention in the thyroid. Possible disturbances and measuring uncertainties of these parameters are presented and discussed. In spite of the discussed uncertainties in dosimetry, due to its high therapeutic width radioiodine therapy is a very successful procedure to cure hyperthyroidism or to reduce goitre volume with only little side effects.

AIM: The influence of various geometric factors on I uptake measurements for solitary thyroid nodule was systematically investigated to derive an approach, based on routinely performed ultrasound examinations, to correct for the effect of geometric variations. METHODS: The influence of size, shape, and position of a thyroid nodule, neck-to-detector distance and neck curvature on the uptake value was analyzed with a three-dimensional model. Uptake measurements using a tissue-equivalent neck phantom were carried out to verify the calculated correction factors and also to check the influence of scatter. Sonograms of 92 patients with solitary nodules were analyzed to correct for geometric variations. RESULTS: The correction factors were independent of the size and shape of the nodule, and the activity distribution of the solitary nodules can be approximated by a point source. The correction factors were mainly determined by the nodular depth and by the accuracy of the neck-to-detector distance and were affected to a lesser extent by the lateral position of the nodule as well as the curvature of the neck. The effect of scatter can be neglected if the energy window largely excludes Compton scatter, as is the case in the I uptake measurement. The ultrasound-derived correction factors ranged from 0.85 to 1.25. CONCLUSION: The proposed approach is capable of correcting for the geometric variation for a solitary nodule and can be easily applied in routine clinics. The accuracy of absorbed dose in radioiodine therapy can be improved in particular for nodules located well beneath the neck surface.

SummaryAims: Objective of this prospective study was to evaluate the role of somatostatin receptor scintigraphy (SRS) in advanced renal cell carcinoma (RCC) with respect to potential therapy with somatostatin analogue (SST-A) and to assess the response rate under therapy with SST-A. Patients, methods: 16 patients with documented progression of histologically confirmed advanced RCC were included. Planar whole-body SRS was performed 4, 24 and 48h post i.v. injection of 175–200 MBq 111In-pentetreoide. 5 and 25 h p.i. SPECT of thorax and abdomen were performed. Documentation of somatostatin receptor expression via SRS in >50% of known tumour lesions was the criteria for treatment start with SST-A (Sandostatin LAR®-Depot 30mg i.m. every four weeks). Results: In 9/16 of the patients SRS showed at least one metastasis with moderate (n = 5) or intense (n = 4) tracer uptake. Lesion-based SRS evaluation showed only 12.1% (20/165) of all metastases. Most false-negative lesions were located in the lungs. In two patients, the majority of the known metastases was SRS positive and these patients received SST-A therapy. The first radiographic evaluation after a twomonth interval showed progressive disease in both patients. Conclusions: We conclude that SRS is of limited value in staging of advanced RCC. In our patients SST-A did not result in a growth control of RCC. Consequently, the use of SST-A in advanced RCC seems to be no relevant therapeutic option.

Rationale and Objectives In recent years, picture archiving and communication systems and electronic transfer of radiologic images using the digital imaging and communications in medicine file standard has become more widely employed in diagnostic radiology. It seems to be likely that nuclear medicine will be integrated within such systems. On the other hand, many departments possess older nuclear medicine equipment without digital output facilities. There is an increasing tendency to display and archive evaluated images (“save-screens,” printouts) on nondedicated, inexpensive systems using file formats capable of data compression. This was the reason for examining the value of the JPEG format in this pilot study. Materials and Methods Fifty scanned planar bitmap images of the most frequent scintigraphic examinations (thyroid, bone, myocardium, lungs, and kidneys) were compared with JPEG format at different data compressions by two blinded observers. The visualization of details (eg, pathologic findings) is described for all these images as the visual appearance of the images and the storage capacity required. Results Relevant loss of clinical information did not occur up to compression factors of 0.75. A major decrease of subjective image quality was seen at compression factors >0.90. Compared with bitmap files, the use of these factors reduced the storage capacity required by 98% at a (JPEG-related) compression factor of 0.50, and 99% at a compression factor of 0.90. Compared with the GIF format, a reduction by 4.0–5.7 could be achieved. Conclusions Use of the JPEG format can therefore be recommended to save costs of image transfer or archiving of standard planar scans for nuclear medical evaluation.

Zusammenfassung Hintergrund: Depressivitat und Angstlichkeit zahlen bei Patienten mit Schilddrusenkarzinom (DTC) zu den haufigsten Befindlichkeitssymptomen mit einem wichtigen Einfluss auf die Lebensqualitat. In der vorliegenden Studie wurde das Ziel verfolgt, protektive Faktoren fur Depression und Angst bei DTC-Patienten zu identifizieren. Methodik: In einer konsekutiven Querschnittstudie wurden 230 DTC-Patienten mit der Hospital Anxiety and Depression Scale (HADS-D), der Sense of Coherence Skala (SOC) und dem Fragebogen zu Sozialer Unterstutzung (F-SOZU) untersucht. Ergebnisse: Eine hoch signifikante Korrelation zeigte sich zwischen Depression und Angstlichkeit (r = .633, p = 0,001). Soziale Unterstutzung und Sense of Coherence hingegen korrelierten sehr signifikant negativ sowohl mit Depression als auch mit Angstlichkeit (beide p 0,001). Geringer, dennoch signifikant, fiel die Korrelation zwischen Alter und Angstlichkeit aus (r = -.19; p 0,005). Der TSH-Spiegel als Mas fur die Auspragung der Hypothyreo...

Nodal involvement is an independent risk factor of recurrence in papillary thyroid cancer (PTC). Neither the international guidelines nor the recently introduced ongoing risk adaptation concept consider the extent of initial surgical clearance of radioiodine sensitive lymph node metastases in their stratification systems. We investigated the prognostic relevance of incomplete initial surgical clearance in patients with purely lymphogeneous metastatic PTC (pN1 M0) despite successful radioiodine therapy. Accurate assessment of pre-ablative nodal status was attempted using PET/CT studies with both (124)I-NaI and (18)F-FDG along with high-resolution cervical ultrasound.Sixty-five patients with histologically diagnosed lymph node metastases (pN1 M0) were retrospectively analyzed. Patients with iodine-negative lymph node metastases diagnosed by (18)F-FDG PET/CT or distant metastases were excluded from the analysis. The association of disease recurrence with the pre-ablative nodal status, as well as other baseline characteristics, were examined applying nonparametric tests for independent samples and multiple regression analysis. Patients with persistent lymph node metastases in (124)I-NaI PET/CT were further divided according to the additional presence or absence of FDG-uptake in (18)F-FDG PET/CT. Survival analyses were performed using Kaplan-Meier curves and the Cox proportional hazards model for uni- and multivariate analyses to assess the influence of prognostic factors on progression free survival (PFS).Incomplete metastatic lymph node resection captured by (124)I-NaI PET/CT (n = 33) was an independent risk factor for recurrence (61 % vs 25 %, p = 0.006) and shorter PFS (46 months vs not reached, HR 4.0 [95 %-CI, 1.7-9.2], p = 0.001). Ultrasound could detect lymph node metastases only in 19/33 patients (58 %). Among patients with positive nodal status, FDG-avidity of metastatic iodine positive lymph nodes worsened the outcome (16 vs 69 months, p = 0.047). From all other investigated factors including age, N-stage (N1a vs N1b), and T-Stage (T4 vs T1-3), only large tumor size (pT4) had a significant impact on PFS (HR 2.9 [95 %-CI, 1.3-6.4], p = 0.007).Incomplete initial surgical clearance of lymph node metastases even after successful radioiodine therapy may increase the chances of recurrence and is an independent risk factor for impaired survival of patients with PTC. Pre-ablative (dual tracer PET/CT) imaging with (124)I-Na and (18)F provides a prognostic tool for these patients and may considerably complement the current risk stratification systems.

SummaryAim: A theoretical dosimetry-based model was applied to estimate the lowest effective radioiodine activity for thyroid remnant ablation of low-risk differentiated thyroid cancer patients. Patients, methods: The model is based on the distribution of the absorbed (radiation) dose per administered radioiodine activity and the absorbed dose threshold of 300 Gy for thyroid remnants, the level believed to destroy most thyroid remnants. For this purpose, 124I PET/CT images of 49 thyroid-ectomised patients were retrospectively analysed to measure the distribution of the (average) absorbed doses to thyroid remnant per administered 131I activity. The fraction of thyroid remnants that received at least 300 Gy was determined for standard activities between 0.37 and 5.55 GBq. The lower activity was considered to be equally effective to that obtained with higher activity if the (absolute) fraction difference was below 5%. Results: A total of 62 thyroid remnants were included. The medians and ranges (in parentheses) for the absorbed dose per unit 131I activity were 359 Gy/GBq (34 to 1825 Gy/ GBq). The fractions of thyroid remnants receiving more than 300 Gy at different therapy activities (within parentheses) were 60% (1.11 GBq), 76% (1.85 GBq), 79% (2.22 GBq), and 81–82% for activities between 2.59 and 3.70 GBq. The therapy activity of 1.11 GBq is considerably less effective than that of 1.85 or 2.22 GBq; therapy activities were equally effective in the range between 2.22 to 3.70 GBq. Conclusion: On the basis of the model and the patients' data included, the lowest effective therapy activity appears to be approximately 2.2 GBq to ablate thyroid remnants. The results of this study may help to guide the design of prospective clinical studies.