Connectivity based on glucose dynamics reveals exaggerated sensorimotor network coupling on subject-level in Parkinson's disease.

PURPOSE: While fMRI provides information on the temporal changes in blood oxygenation, 2- [18F]fluoro-2-deoxy-D-glucose ([18F]FDG)-PET has traditionally offered a static snapshot of brain glucose consumption. As a result, studies investigating metabolic brain networks as potential biomarkers for neurodegeneration have primarily been conducted at the group level. However, recent pioneering studies introduced time-resolved [18F]FDG-PET with constant infusion, which enables metabolic connectivity studies at the individual level. METHODS: In the current study, this technique was employed to explore Parkinson's disease (PD)-related alterations in individual metabolic connectivity, in comparison to inter-subject measures and hemodynamic connectivity. Fifteen PD patients and 14 healthy controls with comparable cognition underwent sequential resting-state dynamic PET with constant infusion and functional MRI. Intrinsic networks were identified by independent component analysis and interregional connectivity calculated for summed static PET images, PET time series and functional MRI. RESULTS: Our findings revealed an intrinsic sensorimotor network in PD patients that has not been previously observed to this extent. In PD, a significantly higher number of connections in cortical motor areas was observed compared to elderly control subjects, as indicated by both static PET and functional MRI (pBonferroni-Holm = 0.027), as well as constant infusion PET and functional MRI connectomes (pBonferroni-Holm = 0.012). This intensified coupling was associated with disease severity (ρ = 0.56, p = 0.036). CONCLUSION: Metabolic connectivity, as revealed by both static and dynamic PET, provides unique information on metabolic network activity. Subject-level metabolic connectivity based on constant infusion PET may serve as a potential marker for the metabolic network signature in neurodegeneration.

Long-term predictive value of highly sensitive thyroglobulin measurement.

OBJECTIVE: To examine the predictive value of unremarkable nonstimulated highly sensitive thyroglobulin (hsTg) measurement with regard to the results of stimulated thyroglobulin (Tg) measurement, diagnostic whole-body scintigraphy, recurrence and differentiated thyroid cancer (DTC)-related death. DESIGN, PATIENTS AND MEASUREMENTS: We retrospectively analysed the data of all 461 (410 without anti-Tg-antibodies [TgAbs], 51 with) DTC patients who were referred to our department for treatment and follow-up care of differentiated thyroid cancer from 2004 onwards, and in whom at least one posttreatment Tg value was measured in our hospital at least 3 months after I-131 ablation. RESULTS: In the group of TgAb-negative patients, 2.0% of patients with an unstimulated Tg < 0.1 ng/ml showed a stimulated Tg ≥ 1.0 ng/ml, whereas this happened in 77.6% with an unstimulated Tg ≥ 0.1 but <1.0 ng/ml. An unstimulated hsTg ≥ 0.1 ng/ml had a sensitivity specificity positive and negative predictive value of 90.0%, 94.1%, 77.6% and 97.6%, respectively, for a stimulated Tg ≥ 1.0 ng/ml. In TgAb-positive patients, this was 75%, 97%, 75% and 97%, respectively. An unstimulated Tg ≥ 0.1 ng/ml did not significantly discriminate with regard to the risk of DTC-related death (p = .06), but ≥1.0 ng/ml did (p = .012), as did a stimulated Tg ≥ 1.0 ng/ml (p = .029). Excluding patients with distant metastases at diagnosis nullifies this significance. CONCLUSION: Except for patients with distant metastases, both TgAb negative and TgAb positive patients with an undetectable nonstimulated hsTg measurement have a very good prognosis. The high net present value of unstimulated hsTg testing means that further diagnostic procedures can be omitted in such patients.

The EANM guideline on radioiodine therapy of benign thyroid disease.

This document provides the new EANM guideline on radioiodine therapy of benign thyroid disease. Its aim is to guide nuclear medicine physicians, endocrinologists, and practitioners in the selection of patients for radioiodine therapy. Its recommendations on patients' preparation, empiric and dosimetric therapeutic approaches, applied radioiodine activity, radiation protection requirements, and patients follow-up after administration of radioiodine therapy are extensively discussed.

Current research topics in FAPI theranostics: a bibliometric analysis.

PURPOSE: The study aimed to provide a comprehensive bibliometric overview of the current scientific publications on fibroblast activation protein inhibitor (FAPI) positron emission tomography imaging and radionuclide therapy. METHODS: A PubMed search was performed to identify all MEDLINE-indexed publications on FAPI imaging and radionuclide therapy. The last update was performed on 31 May 2022. An online database of this literature was created, and hierarchical topic-related tags were subsequently assigned to all relevant studies. Frequency analysis was used to evaluate the distribution of the following characteristics: first author's country of origin, journal of publication, study design, imaging techniques and radiopharmaceutical used, histopathological correlation, the type of cancer, and benign disease/uptake types evaluated. RESULTS: A total of 294 relevant publications on original studies were identified, consisting of 209 (71%) case reports/series and 85 cohort studies (29%). The majority of studies focused on imaging topics, predominantly comparing uptake on FAPI-PET/CT with 2-[18F]FDG-PET/CT, anatomical imaging, and/or histopathology results. 68% of studies focused on malignancies, with gastro-intestinal cancer, hepato-pancreato-biliary cancer, mixed cancers/metastases, lung cancer, sarcoma, head and neck cancer, and breast cancer being the most frequently reported. 42% of studies focused on benign disease categories, with cardiovascular, musculoskeletal, HPB, head and neck, and IgG4-related disease as most common categories. 16/294 (5%) studies focused on radionuclide therapy, with preliminary reports of acceptable toxicity profiles, tumour activity retention, and suggestion of disease control. CONCLUSION: FAPI research is rapidly expanding from diagnostic studies in malignancies and benign diseases to the first reports of salvage radionuclide therapy. The research activity needs to shift now from low-level-of-evidence case reports and series to prospectively designed studies in homogenous patient groups to provide evidence on how and in which clinical situations FAPI theranostics can be of added value to clinical care. We have provided an overview of current research topics to build upon.

Normal organ dosimetry for thyroid cancer patients treated with radioiodine as part of the multi-centre multi-national Horizon 2020 MEDIRAD project.

PURPOSE: Dosimetry is rarely performed for the treatment of differentiated thyroid cancer patients with Na[131I]I (radioiodine), and information regarding absorbed doses delivered is limited. Collection of dosimetry data in a multi-centre setting requires standardised quantitative imaging and dosimetry. A multi-national, multi-centre clinical study was performed to assess absorbed doses delivered to normal organs for differentiated thyroid cancer patients treated with Na[131I]I. METHODS: Patients were enrolled in four centres and administered fixed activities of 1.1 or 3.7 GBq of Na[131I]I using rhTSH stimulation or under thyroid hormone withdrawal according to local protocols. Patients were imaged using SPECT(/CT) at variable imaging time-points following standardised acquisition and reconstruction protocols. Whole-body retention data were collected. Dosimetry for normal organs was performed at two dosimetry centres and results collated. RESULTS: One hundred and five patients were recruited. Median absorbed doses per unit administered activity of 0.44, 0.14, 0.05 and 0.16 mGy/MBq were determined for the salivary glands of patients treated at centre 1, 2, 3 and 4, respectively. Median whole-body absorbed doses for 1.1 and 3.7 GBq were 0.05 Gy and 0.16 Gy, respectively. Median whole-body absorbed doses per unit administered activity of 0.04, 0.05, 0.04 and 0.04 mGy/MBq were calculated for centre 1, 2, 3 and 4, respectively. CONCLUSIONS: A wide range of normal organ doses were observed for differentiated thyroid cancer patients treated with Na[131I]I, highlighting the necessity for individualised dosimetry. The results show that data may be collated from multiple centres if minimum standards for the acquisition and dosimetry protocols can be achieved.

EANM dosimetry committee recommendations for dosimetry of 177Lu-labelled somatostatin-receptor- and PSMA-targeting ligands.

The purpose of the EANM Dosimetry Committee is to provide recommendations and guidance to scientists and clinicians on patient-specific dosimetry. Radiopharmaceuticals labelled with lutetium-177 (177Lu) are increasingly used for therapeutic applications, in particular for the treatment of metastatic neuroendocrine tumours using ligands for somatostatin receptors and prostate adenocarcinoma with small-molecule PSMA-targeting ligands. This paper provides an overview of reported dosimetry data for these therapies and summarises current knowledge about radiation-induced side effects on normal tissues and dose-effect relationships for tumours. Dosimetry methods and data are summarised for kidneys, bone marrow, salivary glands, lacrimal glands, pituitary glands, tumours, and the skin in case of radiopharmaceutical extravasation. Where applicable, taking into account the present status of the field and recent evidence in the literature, guidance is provided. The purpose of these recommendations is to encourage the practice of patient-specific dosimetry in therapy with 177Lu-labelled compounds. The proposed methods should be within the scope of centres offering therapy with 177Lu-labelled ligands for somatostatin receptors or small-molecule PSMA.

An essential practice summary of the new EANM guidelines for parathyroid imaging.

Parathyroid imaging is essential for the detection and localization of hyperfunctioning parathyroid tissue in patients with primary hyperparathyroidism (pHPT). Surgical treatment of pHPT mainly consists of minimally invasive parathyroidectomy (MIP), as a single adenoma represents the most common cause of this endocrine disorder. Successful surgery requires an experienced surgeon and relies on the correct preoperative detection and localization of hyperfunctioning parathyroid glands. Failure to preoperatively identify the culprit parathyroid gland by imaging may entail a more invasive surgical approach, including bilateral open neck exploration, with higher morbidity compared to minimally invasive parathyroidectomy. Parathyroid imaging may be also useful before surgery in case of secondary hyperparathyroidism (sHPT) or hereditary disorders (MEN 1, 2, 4) as it enables correct localization of typically located parathyroid glands, detection of ectopic as well as supernumerary glands. It is now accepted by most surgeons experienced in parathyroid surgery that preoperative imaging plays a key role in their patients' management. Recently, the European Association of Nuclear Medicine (EANM) issued an updated version of its Guidelines on parathyroid imaging. Its aim is to precise the role and the advantages and drawbacks of the various imaging modalities proposed or well established in the preoperative imaging strategy. It also aims to favor high performance in indicating, performing, and interpreting those examinations. The objective of the present article is to offer a summary of those recent EANM Guidelines and their originality among other Guidelines in this domain issued by societies of nuclear medicine physicians or other disciplines.

Thyroglobulin and thyroglobulin antibodies: assay-dependent management consequences in patients with differentiated thyroid carcinoma.

OBJECTIVES: International guidelines recommend fixed cut-off values for thyroglobulin (Tg). These cut-offs do not take potential assay differences into account. This study aimed to evaluate if different assays for Tg and Tg antibodies (TgAb) affect management guidance for differentiated thyroid cancer (DTC) patients. METHODS: In 793 samples derived from 413 patients with DTC, Tg and TgAb were simultaneously measured with two immunometric assays: Immulite 2000XPi and Kryptor compact plus. In addition, a qualitative measurement for TgAb interference (recovery test) was performed on the Kryptor compact plus platform. The extent to which different assays lead to different classifications of response to therapy was evaluated when applying the current cut-offs for Tg. RESULTS: Mean Tg concentrations were 37.4% lower with Kryptor as compared with Immulite. Applying guideline based cut-off values for Tg, 33 (4.7%) samples had a Tg-on concentration ≥1.0 µg/L with Immulite and <1.0 µg/L with Kryptor. Of the samples tested as TgAb+ with at least one assay (n=125), 68 (54.4%) samples showed discrepancy in TgAb status. Differences between Immulite and Kryptor measurements resulted in a change in the response to therapy classification in 94 (12.0%) measurements derived from 67 (16.2%) individual patients. CONCLUSIONS: A substantial portion of DTC patients were classified differently dependent on which Tg and TgAb assays are used, when applying the cut-off values as defined in clinical guidelines. Such differences can significantly affect clinical management. In the context of large between-method variation, the recommended Tg cut-offs in guidelines should be used with wisdom rather than as fixed cut-offs.

EANM position paper on article 56 of the Council Directive 2013/59/Euratom (basic safety standards) for nuclear medicine therapy.

The EC Directive 2013/59/Euratom states in article 56 that exposures of target volumes in nuclear medicine treatments shall be individually planned and their delivery appropriately verified. The Directive also mentions that medical physics experts should always be appropriately involved in those treatments. Although it is obvious that, in nuclear medicine practice, every nuclear medicine physician and physicist should follow national rules and legislation, the EANM considered it necessary to provide guidance on how to interpret the Directive statements for nuclear medicine treatments.For this purpose, the EANM proposes to distinguish three levels in compliance to the optimization principle in the directive, inspired by the indication of levels in prescribing, recording and reporting of absorbed doses after radiotherapy defined by the International Commission on Radiation Units and Measurements (ICRU): Most nuclear medicine treatments currently applied in Europe are standardized. The minimum requirement for those treatments is ICRU level 1 ("activity-based prescription and patient-averaged dosimetry"), which is defined by administering the activity within 10% of the intended activity, typically according to the package insert or to the respective EANM guidelines, followed by verification of the therapy delivery, if applicable. Non-standardized treatments are essentially those in developmental phase or approved radiopharmaceuticals being used off-label with significantly (> 25% more than in the label) higher activities. These treatments should comply with ICRU level 2 ("activity-based prescription and patient-specific dosimetry"), which implies recording and reporting of the absorbed dose to organs at risk and optionally the absorbed dose to treatment regions. The EANM strongly encourages to foster research that eventually leads to treatment planning according to ICRU level 3 ("dosimetry-guided patient-specific prescription and verification"), whenever possible and relevant. Evidence for superiority of therapy prescription on basis of patient-specific dosimetry has not been obtained. However, the authors believe that a better understanding of therapy dosimetry, i.e. how much and where the energy is delivered, and radiobiology, i.e. radiation-related processes in tissues, are keys to the long-term improvement of our treatments.

Higher thyroid hormone levels and cancer.

PURPOSE: This narrative review aims to summarize the relationship between hyperthyroidism, upper reference range thyroid hormone (TH) levels, and cancer, and to address the clinical management of hyperthyroidism in cancer patients. METHODS: A comprehensive search was performed by an independent reviewer through Google Scholar and PubMed Electronic databases. All searches were restricted to English language manuscripts published between 2000 and 2020. RESULTS: Numerous in vitro, in vivo, and population-based studies suggest cancer-stimulating effect of triiodothyronine and thyroxin. THs are presented as mediators for tumor growth, proliferation, and progression. Many population and case-control studies suggest an increased risk of several solid but also hematologic malignancies in relation to hyperthyroidism and upper normal range TH levels. However, results are not unambiguous. In this review, we will summarize population and case-control studies that investigated the relationship between hyperthyroidism, upper reference range TH levels, lower thyrotropin (TSH) levels, lower reference range TSH levels with cancer risk, cancer prognosis, and cancer outcome. The vast majority of evidence suggests an association between clinical and subclinical hyperthyroidism with the risk of developing several types of cancer. Furthermore, hyperthyroidism is also linked with a poorer cancer prognosis. In this review, we will also discuss the diagnosis of hyperthyroidism in patients with pre-existing cancer and cover the management of hyperthyroidism in cancer patients, with special attention on the role of nuclear medicine. CONCLUSIONS: It is crucial to emphasize the importance of the rapid establishment of euthyroidism, and consequently, the importance of radioiodine therapy, as the therapy of choice in most cancer patients. We want to show that in this day and age there still is a high relevance for I-131 to achieve a permanent solution and thus likely reduce the risk of adverse influence of hyperthyroidism on the occurrence of new and course of existing cancer cases.

The EANM practice guidelines for parathyroid imaging.

INTRODUCTION: Nuclear medicine parathyroid imaging is important in the identification of hyperfunctioning parathyroid glands in primary hyperparathyroidism (pHPT), but it may be also valuable before surgical treatment in secondary hyperparathyroidism (sHPT). Parathyroid radionuclide imaging with scintigraphy or positron emission tomography (PET) is a highly sensitive procedure for the assessment of the presence and number of hyperfunctioning parathyroid glands, located either at typical sites or ectopically. The treatment of pHPT is mostly directed toward minimally invasive parathyroidectomy, especially in cases with a single adenoma. In experienced hands, successful surgery depends mainly on the exact preoperative localization of one or more hyperfunctioning parathyroid adenomas. Failure to preoperatively identify the hyperfunctioning parathyroid gland challenges minimally invasive parathyroidectomy and might require bilateral open neck exploration. METHODS: Over a decade has now passed since the European Association of Nuclear Medicine (EANM) issued the first edition of the guideline on parathyroid imaging, and a number of new insights and techniques have been developed since. The aim of the present document is to provide state-of-the-art guidelines for nuclear medicine physicians performing parathyroid scintigraphy, single-photon emission computed tomography/computed tomography (SPECT/CT), positron emission tomography/computed tomography (PET/CT), and positron emission tomography/magnetic resonance imaging (PET/MRI) in patients with pHPT, as well as in those with sHPT. CONCLUSION: These guidelines are written and authorized by the EANM to promote optimal parathyroid imaging. They will assist nuclear medicine physicians in the detection and correct localization of hyperfunctioning parathyroid lesions.

Questions and Controversies in the Clinical Application of Tyrosine Kinase Inhibitors to Treat Patients with Radioiodine-Refractory Differentiated Thyroid Carcinoma: Expert Perspectives.

Notwithstanding regulatory approval of lenvatinib and sorafenib to treat radioiodine-refractory differentiated thyroid carcinoma (RAI-R DTC), important questions and controversies persist regarding this use of these tyrosine kinase inhibitors (TKIs). RAI-R DTC experts from German tertiary referral centers convened to identify and explore such issues; this paper summarizes their discussions. One challenge is determining when to start TKI therapy. Decision-making should be shared between patients and multidisciplinary caregivers, and should consider tumor size/burden, growth rate, and site(s), the key drivers of RAI-R DTC morbidity and mortality, along with current and projected tumor-related symptomatology, co-morbidities, and performance status. Another question involves choice of first-line TKIs. Currently, lenvatinib is generally preferred, due to greater increase in progression-free survival versus placebo treatment and higher response rate in its pivotal trial versus that of sorafenib; additionally, in those studies, lenvatinib but not sorafenib showed overall survival benefit in subgroup analysis. Whether recommended maximum or lower TKI starting doses better balance anti-tumor effects versus tolerability is also unresolved. Exploratory analyses of lenvatinib pivotal study data suggest dose-response effects, possibly favoring higher dosing; however, results are awaited of a prospective comparison of lenvatinib starting regimens. Some controversy surrounds determination of net therapeutic benefit, the key criterion for continuing TKI therapy: if tolerability is acceptable, overall disease control may justify further treatment despite limited but manageable progression. Future research should assess potential guideposts for starting TKIs; fine-tune dosing strategies and further characterize antitumor efficacy; and evaluate interventions to prevent and/or treat TKI toxicity, particularly palmar-plantar erythrodysesthesia and fatigue.

False positive FDG uptake in melanoma patients treated with talimogene laherparepvec (T-VEC).

Talimogene laherparepvec (T-VEC) is a genetically modified herpes simplex virus-1-based oncolytic immunotherapy and has been approved for the local treatment of unresectable (stage IIIB/C and IVM1a) cutaneous melanoma. During T-VEC treatment, tumor response is often evaluated using [18F]2-fluoro-2-deoxy- d-glucose(FDG) positron emission tomography/computed tomography (PET/CT). In a Dutch cohort (n = 173), almost one-third of patients developed new-onset FDG uptake in uninjected locoregional lymph nodes during T-VEC. In 36 out of 53 (68%) patients with new nodal FDG uptake, nuclear medicine physicians classified this FDG uptake as "suspected metastases" without clinical or pathological confirmation in the majority of patients. These false positive results indicate that new-onset FDG uptake in locoregional lymph nodes during T-VEC treatment does not necessarily reflect progressive disease, but may be associated with immune infiltration. In current clinical practice, physicians should be aware of the high false positive rate of FDG uptake during treatment with T-VEC in patients with melanoma. Therefore, pathological examination of lymph node lesions with new FDG uptake is recommended to differentiate between progressive disease and immune infiltration after treatment with T-VEC.

Clinical performance of calcitonin and procalcitonin Elecsys® immunoassays in patients with medullary thyroid carcinoma.

OBJECTIVES: Medullary thyroid carcinoma (MTC) is caused by a malignant transformation in the parafollicular C-cells of the thyroid, where calcitonin (CT) is released. Nowadays, CT is the main tumor marker used in the diagnosis and follow-up of MTC patients. Nonetheless, procalcitonin (PCT) has recently been proposed as a useful complementary/alternative biomarker in MTC. Our aims were to investigate the diagnostic performance of CT and PCT and their combination in the differential diagnosis between active and inactive MTC and between MTC and non-MTC thyroid diseases, respectively. METHODS: Serum samples were collected from 16 patients with active (i.e. primary tumour before surgery or post-surgical recurrent disease) and 23 with inactive (i.e. complete remission) MTC, 125 patients with non-MTC benign thyroid disease and 62 patients with non-MTC thyroid cancers, respectively. Elecsys® CT and PCT measurements were simultaneously performed on the Cobas e601 platform (Roche Diagnostics, Rotkreutz, Switzerland). RESULTS: Both CT and PCT median values in active MTC (94 pmol/L and 1.17 ng/mL, respectively) were significantly higher compared with inactive MTC (0.28 and 0.06) and either benign (0.37 and 0.06) or malignant (0.28 and 0.06) non-MTC. Undetectable PCT was found in five non-MTC patients with false positive CT results. CONCLUSIONS: Elecsys® PCT assay is a highly sensitive and specific alternative MTC marker. At the very least it appears useful in patients with positive CT results as negative PCT values securely exclude active MTC. The availability of both markers on the same automated platform facilitates reflex or reflective strategies to refine the laboratory diagnosis.

Differentiated thyroid cancer patients potentially benefitting from postoperative I-131 therapy: a review of the literature of the past decade.

BACKGROUND: Since the last major review of literature on the benefit of I-131 therapy, the continued debate on postoperative radioiodine treatment (RIT) in differentiated thyroid carcinoma (DTC) has led to a number of further studies being published on this topic. AIM: The aim of the present paper is to report the results of an updated structured review of the literature pertaining to the prognostic benefits of postoperative RIT in DTC in terms of recurrence-free and disease-specific survival. METHODS: A systematic search of the literature was performed using the Medline and Cochrane Library database. The search period started in August 2007 and ended on December 6, 2017. Search terms used included "differentiated thyroid cancer" and "radioiodine therapy" amended by specific terms for recurrence/disease-free survival or overall and/or cancer-specific survival. Included in the search were systematic reviews, randomized clinical trials, or cohort studies consisting of both patients who underwent postoperative RIT and patients treated by surgery alone. RESULTS: Eleven retrospective cohort studies met the defined inclusion criteria and were included in the present review. Results of the studies were mixed, with some showing a benefit of RIT even in microcarcinoma whereas others showed no benefit at all. CONCLUSION: Literature published in the last decade offers data that support adjuvant postoperative RIT in DTC patients with a tumor diameter exceeding 1 cm. Therefore, at least until randomized prospective studies prove otherwise, the prescription of adjuvant I-131 treatment to all DTC patients with a primary tumor diameter exceeding 1 cm remains a reasonable option.

EANM practice guideline for PET/CT imaging in medullary thyroid carcinoma.

BACKGROUND: Medullary thyroid carcinoma (MTC) is a malignant tumour derived from the para-follicular thyroid C cells. It may occur in sporadic or hereditary forms and surgery represent the primary cure. METHODS: Ultrasound examination and, in selected cases, cross-sectional anatomic imaging procedures, are adopted to stage the disease before primary surgery while different anatomic/morphologic and functional/molecular imaging procedures can be adopted in detecting persistent/recurrent disease. Positron emitting radiopharmaceuticals including fluorine-18 fluorodeoxyglucose (18F-FDG), fluorine-18 dihydroxyphenylalanine (18F-FDOPA) and somatostatin analogues labelled with gallium-68 (68Ga-SSA) tracks different metabolic pathways or receptor expression/functioning, and proved to be useful in detecting MTC recurrences/metastasis. CONCLUSIONS: This practice guideline from the Thyroid Committee of the European Association of Nuclear Medicine (EANM), with involvement of external experts, provides recommendations based on updated literature's evidences. The purpose of this practice guideline is to assist imaging specialists and clinicians in recommending, performing and interpreting the results of PET/CT with various radiopharmaceuticals in patients with MTC.

68 Ga-PSMA-PET/CT helps to select patients for salvage radical prostatectomy with local recurrence after primary radiotherapy for prostate cancer.

OBJECTIVE: To investigate the diagnostic performance of gallium-68 prostate-specific membrane antigen positron emission tomography/computed tomography (68 Ga-PSMA PET/CT) in patients with recurrent prostate cancer with regard to the presence of lymph node metastases (LNM) and local recurrences after primary radiotherapy. PATIENTS AND METHODS: We retrospectively reviewed 142 patients following salvage radical prostatectomy (sRP), 50 of which had a 68 Ga-PSMA PET/CT performed as a preoperative staging module. Predictive clinical parameters were analysed in a multivariate Cox regression analysis. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) and the accuracy of 68 Ga-PSMA PET/CT were analysed with regard to LNM and local recurrence. RESULTS: In all, 613 lymph nodes were resected in 40 patients and 23 lymph nodes had metastatic deposits in 14 patients. In all patients local recurrence could have been found with 68 Ga-PSMA PET/CT. Sensitivity, specificity, PPV and NPV and accuracy on a per lymph node basis were 34.78% (16.38-57.2%), 100% (99.38-100%), 100%, 97.52% (96.69-98.15%) and 97.55% (96.00-98.62%). For detecting local recurrence, the sensitivity and PPV were both 100% with an accuracy of 100% (92.89-100%). CONCLUSION: 68 Ga-PSMA PET/CT should be the standard imaging in biochemical recurrent prostate cancer. With this imaging module one detects first local recurrence and can detect locoregional and distant metastases more precisely than standard CT and bone scan.

The time point of completion thyroidectomy has no prognostic impact in patients with differentiated thyroid cancer.

BACKGROUND: After partial resection of the thyroid gland, a second operation referred to as "completion thyroidectomy" may be required if histopathological analysis indicates the presence of differentiated thyroid cancer (DTC). Although there is little evidence, it is assumed that the time point of completion thyroidectomy is not critical for oncological prognosis of patients with DTC. We assessed whether patients with total thyroidectomy (TTx) in a two-step procedure have an equal long-term prognosis with regard to disease-specific survival (DSS) compared to patients immediately undergoing total thyroidectomy in a one-step procedure. METHODS: A database study using the Würzburg thyroid cancer database with 2258 patients with pT1a-pT4b tumours DTC who were operated between 1980 and 2016 was carried out. RESULTS: A total of 277 patients with papillary microcarcinoma pT1aN0M0 were treated by hemithyroidectomy. TTx as one-step procedure was performed in 1114 patients compared to 867 with TTx as a two-step procedure. Patients with papillary thyroid cancer more frequently had a TTx as one-step procedure than follicular thyroid cancer patients (59.4% vs 47%; P < 0.001). Compared to a one-step thyroidectomy, overall complication rate was not different compared to patients undergoing a single operation. Multivariate analysis showed that the presence of distant metastases, T-stage and age at diagnosis were the only independent determinants for DTC-specific survival, regardless of a one- or two-time thyroidectomy. CONCLUSION: The present study on the largest of such patient collectives provides evidence that a delayed completion operation does not affect DSS in DTC, nor does it lead to a significant increase in complication rates.

Advantages of dosimetry in 131I therapy of differentiated thyroid carcinoma.

For advanced differentiated thyroid carcinoma (DTC) several iodine-131 (131I) activity selection strategies are available. The most common approach empirical activity selection, in which the physician chooses an activity based on convention, experience and patient related parameters. The second available strategy is to perform lesion dosimetry. In this case, the activity to be administered is determined after a pretherapeutic dosimetric assessment to calculate the minimal activity required to achieve an effective absorbed dose or a maximum safe activity based on the delivered blood/bone marrow absorbed dose of 2 Gy as determined by blood and whole-body measurements. In contrast to the situation for lesion-based dosimetry, for the maximum safe activity-based approach several studies on outcome are available. In the present paper, an argument for the use of dosimetry in advanced DTC will be presented.

Measuring thyroglobulin in patients with thyroglobulin autoantibodies: evaluation of the clinical impact of BRAHMS Kryptor® Tg-minirecovery test in a large series of patients with differentiated thyroid carcinoma.

Background The present study was undertaken to evaluate the clinical impact of a thyroglobulin (Tg) minirecovery test (Tg-mRec) in a large series of differentiated thyroid carcinoma (DTC) patients treated and monitored homogeneously in a tertiary referral center. Methods Included were 1120 serum samples from 798 DTC patients. Tg, Tg autoantibodies (TgAb) and Tg-mrec measurements were performed on the automated Kryptor® platform and results compared to the corresponding clinical status. Results Among included samples 228 (20%) were TgAb-positive (TgAb+) and 892 (80%) TgAb-negative (TgAb-), respectively. Tg cutoff points were settled at 0.31 µg/L and 0.15 µg/L for TgAb- and TgAb+ patients, respectively, by ROC curve analysis. The diagnostic performance of serum Tg was reduced in TgAb+ compared to TgAb- patients, however, 87% of TgAb+ patients with recurrent disease and, particularly, all patients with distant metastases were correctly detected by adopting an optimized Tg cutoff for TgAb+ patients. A disturbed recovery was found in only 1% of TgAb- patients and in these cases no clinically relevant information was added by the Tg-mRec. Among TgAb+ patients with undetectable Tg and undisturbed Tg-mRec, no one had recurrent disease. However, a falsely undetectable Tg was demonstrated in two patients with recurrent disease who next to increased TgAb also had a disturbed Tg-mRec test. Conclusions There is no additional clinical benefit from performing Tg-mRec in most patients. It can however be considered in TgAb+ patients with undetectable Tg levels as it may help differentiate between patients with true negative and false negative Tg levels in the presence of such antibodies.