[Update of the S2k guidelines : Surgical treatment of benign thyroid diseases]. / Aktualisierung der S2k-Leitlinie : Operative Therapie benigner Schilddrüsenerkrankungen.

Thyroid resections represent one of the most common operations with 76,140 interventions in the year 2016 in Germany (source Destatis). These are predominantly benign thyroid gland diseases. Recommendations for the operative treatment of benign thyroid diseases were last published by the CAEK in 2010 as S2k guidelines (Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften e.V. [AWMF] 003/002) against the background of increasingly more radical resection procedures. Hemithyroidectomy and thyroidectomy are routinely performed for benign thyroid disease in practice. The operation-specific risks show a clear increase with the extent of the resection. Therefore, weighing-up of the risk-indications ratio between unilateral lobectomy or thyroidectomy necessitates an independent evaluation of the indications for both sides. This principle in particular has been used to update the guidelines. In addition, the previously published recommendations of the CAEK for correct execution and consequences of intraoperative neuromonitoring were included into the guidelines, which in particular serve the aim to avoid bilateral recurrent laryngeal nerve paralysis. Moreover, the recommendations for the treatment of postoperative complications, such as hypoparathyroidism and postoperative infections were revised. The updated guidelines therefore represent the current state of the science as well as the resulting surgical practice.

[Lutetium-177-PSMA radioligand therapy : Consensus within the framework of GKV-funded care between the university hospitals in Aachen, Bonn, Düsseldorf, Essen, and Cologne and the MDK Nordrhein]. / Lutetium-177-PSMA-Radioligandentherapie : Konsensus im Rahmen der GKV-finanzierten Versorgung zwischen den Hochschulkliniken in Aachen, Bonn, Düsseldorf, Essen und Köln und dem MDK Nordrhein.

In the last 3 years, Lutetium-177 prostate-specific membrane antigen radioligand therapy (Lu-177-PSMA-RLT) has received increasing attention in nuclear medicine as a new form of treatment for castration-resistant metastatic prostate cancer. This therapy combines the radionuclide Lutetium-177, which has been therapeutically used in nuclear medicine for many years, with a molecular target of the transmembrane prostate-specific membrane antigen expressed by prostate cancer cells. Since there are no prospective randomized studies on Lu-177-PSMA-RLT and the question of reimbursement has repeatedly been the subject of review by the MDK Nordrhein (Medischenische Dienst der Krankenversicherung), there was a desire because of the increasing number of patients being treated to clarify under which circumstances Lu-177-PSMA-RLT can be reimbursed by German statutory health insurance. The goals of this article are to help treating physicians understand how this new therapy option works, to integrate it in the overall therapy concept for castration-resistant metastatic prostate cancer, and, above all, to use Lu-177-PSMA-RLT-based on the current data-at the right place in the therapy sequence of castration-resistant metastatic prostate cancer.

[Somatostatin receptor PET/CT (SSTR-PET/CT)]. / Somatostatinrezeptor-PET/CT.

The present guideline is focused on quality assurance of somatostatin receptor PET/CT (SSTR-PET/CT) in oncology patients. The document has been developed by a multidisciplinary board of specialists providing consensus of definitions, prerequisites, methodology, operating procedures, assessment, and standardized reporting. In particular, imaging procedures for the two most commonly used radioligands of human SSTR, i. e. 68Ga-DOTATOC and 68Ga-DOTATATE are presented. Overall, SSTR-PET/CT requires close interdisciplinary communication and cooperation of referring and executing medical disciplines, taking into account existing guidelines and recommendations of the European and German medical societies, including the European Association of Nuclear Medicine (EANM), German Society for Endocrinology (DGE), German Society for Nuclear Medicine (DGN) and German Society for Radiology (DRG).

[Relevance of Ablation Therapies for HCC: "A Real Bridging" for Liver Transplantation?]. / Stellenwert der ablativen Tumortherapie beim HCC: "eine reale Brücke" zur Lebertransplantation?

BACKGROUND: The utilisation of interventional ablation procedures in the context of bridging and downstaging plans for hepatocellular carcinomas before liver transplantation is increasing. The aim of the present study was to summarise current data for the application of bridging and downstaging procedures before liver transplantation. METHODS: The present study is based on an extensive investigation of the literature in PubMed. RESULTS of controlled trials, cohort studies, meta-analyses and reviews were included. RESULTS: Recommendations for the usage of bridging procedures for hepatocellular carcinomas within the Milan criteria and an expected waiting time of more than 6 months until transplantation depend on the size of the lesions and have a low level of evidence. After successful downstaging of hepatocellular carcinomas beyond the Milan criteria into the range of the Milan criteria liver transplantation is recommended with a low level of evidence, as well. CONCLUSION: Randomised controlled trials, clearly proving the success of bridging and downstaging procedures, are not available at the time and are not awaited for ethical reasons. Due to the uncomplicated application and low risk for therapy-associated complications, interventional procedures for bridging and downstaging are accepted and recommended.

Imaging with (124)I in differentiated thyroid carcinoma: is PET/MRI superior to PET/CT?

PURPOSE: The aim of this study was to compare integrated PET/CT and PET/MRI for their usefulness in detecting and categorizing cervical iodine-positive lesions in patients with differentiated thyroid cancer using (124)I as tracer. METHODS: The study group comprised 65 patients at high risk of iodine-positive metastasis who underwent PET/CT (low-dose CT scan, PET acquisition time 2 min; PET/CT2) followed by PET/MRI of the neck 24 h after (124)I administration. PET images from both modalities were analysed for the numbers of tracer-positive lesions. Two different acquisition times were used for the comparisons, one matching the PET/CT2 acquisition time (2 min, PET/MRI2) and the other covering the whole MRI scan time (30 min, PET/MRI30). Iodine-positive lesions were categorized as metastasis, thyroid remnant or inconclusive according to their location on the PET/CT images. Morphological information provided by MRI was considered for evaluation of lesions on PET/MRI and for volume information. RESULTS: PET/MRI2 detected significantly more iodine-positive metastases and thyroid remnants than PET/CT2 (72 vs. 60, p = 0.002, and 100 vs. 80, p = 0.001, respectively), but the numbers of patients with at least one tumour lesion identified were not significantly different (21/65 vs. 17/65 patients). PET/MRI30 tended to detect more PET-positive metastases than PET/MRI2 (88 vs. 72), but the difference was not significant (p = 0.07). Of 21 lesions classified as inconclusive on PET/CT, 5 were assigned to metastasis or thyroid remnant when evaluated by PET/MRI. Volume information was available in 34 % of iodine-positive metastases and 2 % of thyroid remnants on PET/MRI. CONCLUSIONS: PET/MRI of the neck was found to be superior to PET/CT in detecting iodine-positive lesions. This was attributed to the higher sensitivity of the PET component, Although helpful in some cases, we found no substantial advantage of PET/MRI over PET/CT in categorizing iodine-positive lesions as either metastasis or thyroid remnant. Volume information provided by MRI for some iodine-positive lesions might be useful in dosimetry.

[Clinical importance of thyroid gland cytology]. / Klinische Bedeutung der Schilddrüsenzytologie.

The cytological evaluation of fine needle biopsies (FNB) of the thyroid gland crucially depends on a close cooperation between clinicians and cytopathologists. Scintigraphy, sonography as well as clinical data and patient history are necessary for a correct interpretation of the indications for FNB; moreover, these data are of outstanding importance for cytopathologists for the correct interpretation of the cytomorphological findings. This overview describes the present standards in the acquisition, technical workup and cytopathological interpretation of thyroid gland tissue obtained by FNB, particularly focusing on the rapidly growing relevance of additional molecular pathological investigations to increase the diagnostic accuracy of thyroid FNB.

Lowest effective 131I activity for thyroid remnant ablation of differentiated thyroid cancer patients. Dosimetry-based model for estimation.

AIM: 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 thyroidectomised 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.

[Peptide receptor radionuclide therapy for patients with somatostatin receptor expressing tumours. German Guideline (S1)]. / Peptidrezeptor-Radionuklidtherapie Somatostatinrezeptor-exprimierender Tumore. DGN-Leitlinie (S1).

This document describes the guideline for peptide receptor radionuclide therapy (PRRT) published by the German Society of Nuclear Medicine (DGN) and accepted by the Association of the Scientific Medical Societies in Germany (AWMF) to be included in the official AWMF Guideline Registry. These recommendations are a prerequisite for the quality management in the treatment of patients with somatostatin receptor expressing tumours using PRRT. They are aimed at guiding nuclear medicine specialists in selecting likely candidates to receive PRRT and to deliver the treatment in a safe and effective manner. The recommendations are based on an interdisciplinary consensus. The document contains background information and definitions and covers the rationale, indications and contraindications for PRRT. Essential topics are the requirements for institutions performing the therapy, e. g. presence of an expert for medical physics, intense cooperation with all colleagues involved in the treatment of a patient, and a certificate of instruction in radiochemical labelling and quality control are required. Furthermore, it is specified which patient data have to be available prior to performance of therapy and how treatment has to be carried out technically. Here, quality control and documentation of labelling are of great importance. After treatment, clinical quality control is mandatory (work-up of therapy data and follow-up of patients). Essential elements of follow-up are specified in detail. The complete treatment inclusive after-care has to be realised in close cooperation with the involved medical disciplines. Generally, the decision for PRRT should be undertaken within the framework of a multi-disciplinary tumour board.

[Differentiated thyroid cancer]. / Differenzierte Schilddrüsenkarzinome.

Thyroid carcinoma is a rare and heterogeneous disease. Initial therapy and follow-up has to be adjusted to the individual risk for an excellent vs. poor prognosis. Differentiated thyroid cancer has a very high cure rate and is treated by surgery, usually followed by radioiodine ablation. Depending on the response to initial therapy the risk for persisting or recurrent disease should be re-evaluated. Continued TSH suppressive levothyroxine therapy is only recommended in high-risk patients. In contrast, metastatic radioiodine-refractory thyroid cancers have a poor prognosis and may benefit from multidisciplinary treatment concepts including tyrosine kinase inhibitors. Due to its complexity, management of thyroid cancer patients should be performed in close collaboration with a specialized thyroid cancer team.

Expression of the cAMP binding protein EPAC1 in thyroid tumors and growth regulation of thyroid cells and thyroid carcinoma cells by EPAC proteins.

The thyrotropin receptor-cAMP pathway is central in growth regulation of thyroid cells and thyroid tumorigenesis, and it regulates expression of thyroid specific genes. Recently, 2 new protein kinase A-independent cAMP effectors named EPAC1 and 2 were described that activate additional intracellular pathways. The aim of our study was to investigate the role of EPAC proteins in growth regulation of thyroid cells and thyroid carcinomas. EPAC1 expression was investigated immunohistochemically in tissues of various thyroid tumors. Utilizing MTT assay, the effect of EPAC stimulation on proliferation in thyroid carcinoma cells and in non-transformed rat FRTL5 cells was investigated. The activation of intracellular signaling pathways was examined by RAP pull-down assay and Western blots. EPAC1 expression was strong in non-oxyphilic follicular thyroid adenomas and carcinomas and in follicular papillary thyroid carcinomas. It was moderate in oxyphilic follicular tumors and classical and tall cell papillary carcinomas. In contrast, EPAC1 expression was low in poorly differentiated carcinomas and very low in anaplastic carcinomas. Thyroid carcinoma cell lines showed no or very weak EPAC1 expression and exhibited no growth-promoting effect after EPAC stimulation. Non-transformed rat FRTL5 cells were growth-stimulated by an EPAC-specific cAMP-analogue and showed EPAC-dependent activation of RAP, ERK, and p70S6 kinase. EPAC1 expression and cellular response to EPAC activation in rat FRTL5 cells reflect cellular responses to cAMP and TSH stimulation in non-transformed thyroid cells. In undifferentiated thyroid carcinomas, loss of EPAC1 expression may be in accordance with the loss of thyroid-specific functions and the loss of responsiveness of the TSHR-cAMP pathway.

Diagnosis of hyperfunctional thyroid nodules: impact of US-elastography.

AIM: 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 significant 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.

Selective internal radiation therapy of hepatic tumours: is coiling of the gastroduodenal artery always beneficial?

AIM: To assess the effect of gastroduodenal artery (GDA) occlusion prior to selective internal radiation therapy (SIRT) with regards to arterial hepato-intestinal collateralization (HIC). MATERIALS AND METHODS: Six hundred and six patients were scheduled for SIRT between 2006 and 2012 at University Hospital Essen, Germany. Digital subtraction angiography (DSA) followed by administration of 99m-technetium labelled human serum albumin microspheres ((99m)Tc-HSAM) and single-photon emission computed tomography combined with computed tomography (SPECT/CT) was initially performed. Depending on vascular anatomy and hepatic tumour load, GDA coil embolization was considered. In subsequent (99m)Tc-HSAM rescans or therapeutic DSA, HIC and its consequences for SIRT were analysed. RESULTS: The GDA was occluded in 86 of 606 patients (14%). Twenty-two of these 86 patients did not undergo SIRT due to the patients' clinical status or SIRT contraindications. In 28 of the remaining 64 patients, newly apparent or reopened HIC were seen either at the site of the proximal GDA (n = 21) or in the periphery of the hepatic arteries (n = 7). In 25 of these 28 patients, the HIC could be occluded or the catheter position could be changed achieving a safe (90)Y application. However, due to the newly visible HIC in three of 28 patients, SIRT was regarded as unsafe and was abandoned. CONCLUSION: Coil embolization of the GDA may induce arterial hepato-intestinal collaterals. Although most of these collaterals do not impede (90)Y administration, SIRT may become unfeasible in specific occasions. Hence, segmental or lobar SIRT instead of a whole-liver approach with coiling of the GDA is recommended.

Hepatic volume changes after lobar selective internal radiation therapy (SIRT) of hepatocellular carcinoma.

AIM: To assess volume changes of treated and non-treated liver segments after selective internal radiation therapy (SIRT) in patients with hepatocellular carcinoma (HCC) and compromised hepatic function due to cirrhosis over a time course of 12 months after SIRT. MATERIALS AND METHODS: All patients underwent SIRT of the right liver lobe with yttrium 90 (Y-90). Absolute volumes of the right liver lobe (RLV) and left liver lobe (LLV) were assessed using computed tomography (CT) before and 1, 3, 6, 9, and 12 months after SIRT. Changes at follow-up relative to baseline volumes were analysed ("normalized" volumes). Furthermore, the relative volume of the LLV [LLV/(RLV + LLV)] was calculated ("relative" volumes). For statistical analysis p < 0.05 was considered statistically significant. RESULTS: Forty-five HCC patients (36 men, nine women, mean age 71.9 years, range 55-90 years) were studied. The mean baseline RLV and LLV reached 1116 ml [95% confidence intervals (CI): 1006-1226 ml] and 601 ml (95% CI: 514-688 ml), respectively. At 6 months following radioembolization, the LLV increased by 30.8% (RLV -33.9%), with the relative LLV increasing from 35% (pre-radioembolization) to 50.5%. RLV further decreased and LLV increased 12 months after SIRT (nRLV -44.9%, nLLV +40.1%, relative LLV 56.5%). All changes were significant. CONCLUSION: Constraints of liver function after radioembolization of one liver lobe can be partially compensated through hypertrophy of the contralateral lobe. The rate of volumetric changes is the highest in the first 6 months following radioembolization. The present data can also be the basis to propagate radiation lobectomy for selected patients, simultaneously providing tumour control and future remnant liver hypertrophy before curative hemihepatectomy.

18FDG-PET to assess recurrence and long term survival in patients with malignant melanoma.

AIM: To assess the diagnostic and prognostic value of FDG-PET/CT in the follow-up of malignant melanoma in comparison to the serum protein S100B. PATIENTS AND METHODS: A total of ninety patients with either low-risk or high-risk malignant melanoma, respectively, were included in this study. The follow-up of the patients was pursuant with the guidelines of the German Dermatological Association. The diagnostic accuracy and diagnostic power were determined for PET/CT and for the serum protein S100B. RESULTS: In 28 of the 90 patients PET/CT was positive in the follow up, 47 patients had an elevated Serum S100B level. Sensitivity, specificity, PPV and NPV of PET/CT for the total groups of patients were 87%, 93%, 87% and 93%. The corresponding values for the serum protein S100B were 65%, 52%, 43% and 74%, respectively. PET/CT positive patients showed a significantly (p < 0.001) higher risk of melanoma associated death compared to patients with PET/CT negative findings. No statistical significance could be found in the 5 year survival rate between the S100B positive and S100B negative patients. CONCLUSION: PET/CT is suitable to confirm or exclude recurrences and can be used to assess the prognosis in melanoma patients. The diagnostic accuracy and the prognostic power is much higher compared to the serum protein S100B.

Correlation of the apparent diffusion coefficient (ADC) with the standardized uptake value (SUV) in hybrid 18F-FDG PET/MRI in non-small cell lung cancer (NSCLC) lesions: initial results.

PURPOSE: To compare the apparent diffusion coefficient (ADC) in non-small cell lung cancer lesions with standardized uptake values (SUV) derived from combined 18F-fluoro-deoxy-glucose-positron emission tomography/magnetic resonance imaging (FDG-PET/MRI) and those derived from FDG-PET/CT. MATERIALS AND METHODS: In 18 consecutive patients with histologically proven NSCLC (17 men, 1 woman; mean age, 61 ± 12 years), whole-body FDG-PET/MRI was performed after whole-body FDG-PET/CT. Regions of interest (ROI) encompassing the entire primary tumor were drawn into FDG-PET/CT and FDG-PET/MR images to determine the maximum and mean standardized uptake value (SUVmax; SUVmean) and into ADC parameter maps to assess mean ADC values. Pearson's correlation coefficients were calculated to compare SUV and ADC values. RESULTS: The SUVmax of NSCLC was 12.3 ± 4.8 [mean ±SD], and the SUVmean was 7.2 ± 2.8 as assessed by FDG-PET/MRI. The SUVmax and SUVmean derived from FDG-PET/CT and FDG-PET/MRI correlated well (R = 0.93; p < 0.001 and R = 0.92; p < 0.001, respectively). The ADCmean of the pulmonary tumors was 187.9 ± 88.8 × 10-5 mm²/s [mean ± SD]. The ADCmean exhibited a significant inverse correlation with the SUVmax (R = -0.72; p < 0.001) as well as with the SUVmean assessed by FDG-PET/MRI (R = -0.71; p < 0.001). CONCLUSION: This simultaneous PET/MRI study corroborates the assumed significant inverse correlation between increased metabolic activity on FDG-PET and restricted diffusion on DWI in NSCLC.Citation Format:

Monte Carlo-based 3-dimensional dosimetry of salivary glands in radioiodine treatment of differentiated thyroid cancer estimated using 124I PET.

AIM: Salivary gland toxicity is of concern in radioiodine treatment of thyroid cancer. Toxicity is often observed while the estimated radiation absorbed dose (AD) values are below expected toxicity thresholds. Monte Carlo-based voxelized 3-dimensional radiobiological dosimetry (3D-RD) calculations of the salivary glands from eight metastatic thyroid cancer patients treated with 131I are presented with the objective of resolving this discrepancy. METHODS: GEANT4 Monte Carlo simulations were performed for 131I, based on pretherapeutic 124I PET/CT imaging corrected for partial volume effect, and the results scaled to the therapeutic administered activities. For patients with external regions of high uptake proximal to the salivary glands, such as thyroid remnants or lymph node metastases, separate simulations were run to quantify the AD contributions from both (A) the salivary glands themselves, and (B) the external proximal region of high uptake (present for five patients). The contribution from the whole body outside the field of view was also estimated using modeling. Voxelized and average ADs and biological effective doses (BEDs) were calculated. RESULTS: The estimated average therapeutic ADs were 2.26 Gy considering all contributions and 1.94 Gy from the self-dose component only. The average contribution from the external region of high uptake was 0.54 Gy. This difference was more pronounced for the submandibular glands (2.64 versus 2.10 Gy) compared to the parotid glands (1.88 Gy versus 1.78 Gy). The BED values were on average only 6.6 % higher than (2.41 Gy) the ADs. CONCLUSION: The external sources of activity contribute significantly to the salivary gland AD, however neither this contribution, nor the radiobiological effect quantified by the BED are in themselves sufficient to explain the clinically observed toxicity.

124I-PET/CT images of differentiated thyroid cancer patients. Distinguishing lymph node metastases from thyroid remnants using kinetic quantities.

UNLABELLED: For an adequate therapy planning and staging of patients with differentiated thyroid cancer (DTC), the correct assignment of thyroid remnants (TRs) and lymph node metastases (LMs) is important. PATIENTS, METHOD: We retrospectively analyzed whether kinetic quantities can help improving LM assignment using serial 124I-PET/CT data. 127 patients with a total of 317 lesions (TR: n = 265; LM: n = 52) received pre-therapy 124I-PET/CT lesion dosimetry using images 24 h and > 96 h after 124I administration. For each lesion, maximum activity concentration (MAC) at 24 h and effective half-life (EHL) were determined. Moreover, the product of MAC and EHL was also investigated as a quantity and is referred to CAQ (cumulated activity proportional quantity). In addition, differences between endogenous and exogenous thyroid-stimulating hormone (TSH) stimulation and between papillary (PTC) and follicular thyroid cancer (FTC) were investigated. RESULTS, CONCLUSION: The median MAC, EHL, and CAQ values in TR were significantly higher than in LM but a clinically relevant cut-off value could not be determined because of high overlapping regions. No significant differences for the three quantities were found for the mode of TSH stimulations, but a significant difference for MAC and CAQ between PTC and FTC.

Estimation of tumour mass in patients with differentiated thyroid carcinoma using serum thyroglobulin.

UNLABELLED: Serum thyroglobulin (Tg) is a reliable tumour marker in follow-up of patients with differentiated thyroid carcinoma (DTC). A positive correlation between Tg level and tumour mass was recently observed, but no attempts were made to derive a numerical relation. The aim of this study was to derive a numerical relationship between serum Tg level and tumour mass that allows optimizing the diagnostic procedures. PATIENTS, METHOD: 78 DTC patients with tumour lesions in either 124I-NaI or 18F-FDG PET/CT were included. For each patient, the total tumour mass was determined functionally in iodine- and FDG-positive lesions as well as morphologically in only CT-positive lesions. The serum Tg level was measured under TSH stimulation prior to imaging. Regression analyses were performed to derive an approach for estimation of the total tumour mass based on Tg levels. RESULTS: A positive correlation of serum Tg and tumour mass was confirmed and a mathematical expression was given to estimate the tumour mass along with its 95% confidence interval using only the serum Tg level. The results demonstrated that the range of predicted tumour mass was higher per serum Tg unit for iodine-positive lesions than for FDG-positive tumour lesions and was higher for follicular than for papillary thyroid carcinoma. CONCLUSION: This study provides an approach to estimate the tumour mass and its 95% confidence intervals in DTC patients using the serum Tg level. The range of the estimated tumour mass for a given Tg level is rather large, and therefore, the approach is of limited value in clinical application.

Success rate of repeated fine needle aspiration biopsy of clinically suspicious thyroid nodules.

UNLABELLED: In this study we evaluated the success rate of double fine needle aspiration biopsy (FNAB) of clinically suspicious thyroid nodules in one session. AIM: The success rate of FNAB in clinical setting is quite low. There were several attempts made to improve the success rate of this method. It is anticipated that a double FNAB in one session would increase the success rate of FNAB. PATIENTS, METHODS: 176 consecutive patients (130 women, 46 men; mean age 56 years ± 11) with at least one clinically suspicious nodule were included in this study. Each individual nodule was biopsied twice (20G- and 21G-needle). In 33 patients, two suspicious nodules were biopsied, accounting for a total of 209 biopsied thyroid nodules. To evaluate the success rate the number of cell formations and the total number of cells in each cell formation were counted. RESULTS: The biopsy with the 20G needle provided in mean 40 cell cluster with a mean of 830 cells whereas the 21G needle provided in mean 41 cell cluster with a mean of 1010 cells. With the 20G needle the success rate was 73%, with the 21G needle 78% and the combination of the both biopsies provided a success rate of 87% (p = 0.01). Based on the number of cell formations and the total number of cells, the difference between the two needle sizes was not significant (p = 0.5 for cell formations and p = 0.9 for the total number of cells, respectively). CONCLUSION: A double FNAB of suspicious thyroid nodules in one session provides a higher success rate, and a 21G needle is sufficient enough.