[Pain reduction by radiosynoviorthesis in rheumatism-induced synovitis of the elbow : Results of a retrospective multicenter data analysis]. / Schmerzreduktion durch Radiosynoviorthese bei rheumatisch bedingter Synovialitis des Ellenbogens : Ergebnisse einer retrospektiven, multizentrischen Datenanalyse.

BACKGROUND: Radiosynoviorthesis (RSO) is a nuclear medical local treatment modality for inflammatory joint diseases. It is indicated in patients with rheumatoid arthritis (RA) in joints with persistent synovitis despite adequate pharmacotherapy. Arthritis of the elbow joint occurs in up to 2/3 of patients with RA. Intra-articular radiotherapy using the beta emitter [186Re] rhenium sulfide leads to sclerosis of the inflamed synovial membrane with subsequent pain alleviation. The clinical efficacy in cubital arthritis, however, has so far only been described in small monocentric studies. OBJECTIVE: The degree of pain alleviation by RSO was analyzed in patients with rheumatoid cubital arthritis, treated in several nuclear medical practices specialized in RSO. MATERIAL AND METHODS: The subjective pain intensity before and after RSO was documented in a total of 107 patients with rheumatic cubital arthritis using a 10-step numeric rating scale (NRS). A difference of ≥ -2 is rated as a significant improvement. Follow-up examinations were done after a mean interval of 14 months after RSO (at least 3 months, maximum 50 months). RESULTS: The mean NRS value was 7.3 ± 2.1 before RSO and 2.8 ± 2.2 after RSO. A significant pain alleviation was seen in 78.5% of all patients treated. The subgroup analysis also showed a significant improvement in the pain symptoms in all groups depending on the time interval between the RSO and the control examination. A significant pain progression was not observed. The degree of pain relief was independent of the time of follow-up. CONCLUSION: Using RSO for local treatment of rheumatoid cubital arthritis leads to a significant and long-lasting pain relief in more than ¾ of the treated patients.

Intra-articular Treatment of Digital Osteoarthritis by Radiosynoviorthesis-Clinical Outcome in Long-term Follow-up.

PURPOSE: This retrospective study analyzed the long-term effects of radiosynoviorthesis (RSO) with special emphasis to local joint pain in patients from 4 different RSO centers in Germany and Austria. METHODS: A total of 168 finger joints in 147 patients with digital joint OA were investigated. The indication for RSO was based on both clinical complaints and a proven synovitis, despite anti-inflammatory pharmacotherapy and previous intra-articular corticosteroid injections. Radiosynoviorthesis was performed according to international guidelines. A numeric visual analog scale (VAS) before and after treatment was used to measure the outcome. Follow-up was done for at least 2 years after treatment, in some patients even over 10 years. RESULTS: Radiosynoviorthesis resulted in a significant reduction of VAS values in most of the patients, lasting for the whole period of follow-up. Two-thirds of the treated joints showed clinically relevant improvement, if a reduction of 30% in VAS values was defined as a reasonable cutoff. The best results were achieved in thumb base joints. CONCLUSIONS: This article confirms that RSO is a suitable treatment option for digital joint OA with a proven synovitis. The analgesic effect is long-lasting and comparable to the success of RSO in patients with rheumatoid arthritis.

The future of radiosynoviorthesis: bright or bleak?

Radiosynoviorthesis (RSO) is a decades known, effective intra-articular nuclear medicine local therapy, with few rare side-effects, in which inflamed synovial membrane is treated by means of colloidal beta-emitters. There are major variations worldwide in terms of acceptance, frequency of use and approved indications for this procedure. Thus, reliable figures that reflect reality are only available for a few countries. A Europe-wide survey revealed that RSO is carried out most frequently in Germany, where RSO is the most common nuclear medicine therapy with about 70,000 joints treated per year. The main indications include synovitis due to rheumatoid arthritis, hemophilia and pigmented villonodular synovitis (PVNS), and depending on national approvals, osteoarthritis. Despite the many indications, there are very few published scientific studies and therefore, RSO evidence is lacking. Reliable data on the clinical usage of RSO and demographics of RSO specialists are only available in Germany, thus we discuss the future challenges of RSO mainly from a German perspective. In the German healthcare system, RSO is performed primarily on an outpatient basis and plays only a minor role in the university setting. The necessary expertise for RSO is therefore lacking, for the most part, at university training centers. Currently, nearly more than three quarters of the German RSO experts are over fifty years old, illustrating a shortage of young talent. In the future, RSO providers from the non-university or private sector will have to cooperate with universities through networks and will have to intensify their cooperation with referring physicians, such as rheumatologist and orthopedic surgeons, and patients in order to maintain a timely and beneficial exchange of information. In networks of RSO experts, the participants must jointly develop and establish training concepts and facilities for future talents, elaborate on guidelines, if clinically useful expand the range of indications, initiate studies to generate further evidence and finally make the procedure more public. In addition, it is worthwhile to apply this process beyond human medicine to other fields, such as medical physics and veterinary medicine. If these points are implemented, the future of RSO will be bright, if it fails, it looks bleak.

[The Baker's cyst - a blunt sword of Damokles in radiosynoviorthesis (RSO)?] / Die Bakerzyste ­ das stumpfe Damoklesschwert bei der Radiosynoviorthese (RSO)?

The existence of a popliteal Baker's cyst was regarded as a contraindication for radiosynoviorthesis of the knee joint since decades. A so-called "ventile mechanism" was discussed leading to a significant concentration of the intraarticularly applied, high energy beta emitting radiopharmaceutical yttrium-90-colloid in the cyst. This cyst arises from a bursa beneath the tendon of the medial head of the gastrocnemius muscle, normally communicating with the knee joint space. Since the cyst wall is much thinner than the knee joint capsule, a radiogenic rupture of the cyst was feared, leading to severe radiogenic necroses of the surrounding soft tissue. Due to this potential hazard, knee joint ultrasound is mandatory prior to radiosynoviorthesis to check for any popliteal cysts. New studies however decline the risk of a radiogenic cyst rupture after an appropriately performed radiosynoviorthesis of the knee joint.In case of a preexistent cyst rupture, the risk of a radiogenic tissue damage remains an issue and magnetic resonance imaging (MRI) is the method of choice to exclude this potential hazard. However, MRI sometimes leads to equivocal results. Scintigraphy of the knee joint after intraarticular application of Tc-99m-nanocolloid offers the possibility to check for the integrity of the Baker's cyst in these patients to be sure that radiosynoviorthesis will not lead to a relevant extraarticular leakage with soft tissue necroses. This study describes the procedure of intracavitary distribution scintigraphy by means of representative case reports.

COVID-19 Pandemic: What Have We Learned and What to Expect in the Future?

The COVID-19 pandemic resulted in an unprecedented and unexpected challenge for societies and healthcare systems, including nuclear medicine providers. This article summarizes the major events imposed on nuclear medicine by COVID-19 from a global perspective, focuses on the major lessons learned regarding attitude, medical procedures, organizational implications and strategical considerations, and then discusses what to expect (and how to prepare) for the future. While the look back to what has happened is clearly evidence based, the look ahead and the conclusions drawn require the disclaimer of only representing the personal opinion and prediction of the authors. The COVID-19 pandemic relentlessly revealed deficiencies on an organizational, systematic and leadership level in nuclear medicine and beyond. Crisis gives us the opportunity to learn and furthermore perpare for the future. The authors' take home messages include the recommendation to focus on developing a culture of responsibility and ownership as opposed to blame, strengthening teams and communication, adapting existing structures based on the lessons learned during COVID-19, as well as establishing an environment of active decision making, prioritizing proposal of solutions rather than simply stating problems, incentivizing support and collaboration, not opposition.

Changes in the global impact of COVID-19 on nuclear medicine departments during 2020: an international follow-up survey.

AIM: As a follow-up to the international survey conducted by the International Atomic Energy Agency (IAEA) in April 2020, this survey aims to provide a situational snapshot of the COVID-19 impact on nuclear medicine services worldwide, 1 year later. The survey was designed to determine the impact of the pandemic at two specific time points: June and October 2020, and compare them to the previously collected data. MATERIALS AND METHODS: A web-based questionnaire, in the same format as the April 2020 survey was disseminated to nuclear medicine facilities worldwide. Survey data was collected using a secure software platform hosted by the IAEA; it was made available for 6 weeks, from November 23 to December 31, 2020. RESULTS: From 505 replies received from 96 countries, data was extracted from 355 questionnaires (of which 338 were fully completed). The responses came from centres across varying regions of the world and with heterogeneous income distributions. Regional differences and challenges across the world were identified and analysed. Globally, the volume of nuclear medicine procedures decreased by 73.3% in June 2020 and 56.9% in October 2020. Among the nuclear medicine procedures, oncological PET studies showed less of a decline in utilization compared to conventional nuclear medicine, particularly nuclear cardiology. The negative impact was also significantly less pronounced in high-income countries. A trend towards a gradual return to the pre-COVID-19 situation of the supply chains of radioisotopes, generators, and other essential materials was evident. CONCLUSION: The year 2020 has a significant decrease in nuclear medicine diagnostic and therapeutic procedures as a result of the pandemic-related challenges. In June, the global decline recorded in the survey was greater than in October when the situation began to show improvement. However, the total number of procedures remained below those recorded in April 2020 and fell to less than half of the volumes normally carried out pre-pandemic.

[Joint DGN, OGNMB and SGNM S1 guideline for radiosynoviorthesis]. / Gemeinsame Handlungsempfehlung (S1-Leitlinie) von DGN, OGNMB und SGNM ­ Radiosynoviorthese ­ Stand: 9/2019 ­ AWMF-Registernummer: 031-023.

This recommendation is intended to provide a guideline for radiosynoviorthesis (RSO) in the effective local treatment of chronic inflammatory (non-infectious) joint diseases. It was developed in an interdisciplinary manner and describes the general objectives, definitions, clinical background information, indication and contraindications of this radionuclide therapy. The requirements to be met by a treatment center, the results of pretherapeutic examinations as well as recommendations on how the treatment should be carried out. Here, organizational and technical issues have been considered. Furthermore, information on the surveillance and follow-up of the treated patients can be found. In general, treatment and follow-up should be done in in close cooperation of the participating disciplines.

[Impact of COVID-19 on Nuclear Medicine Procedures in Germany 2020 - Results of a National Survey]. / Auswirkungen von COVID-19 auf nuklearmedizinische Untersuchungen und Therapien im Verlauf von 2020 ­ Ergebnisse einer nationalen Umfrage.

INTRODUCTION: The COVID-19 pandemic imposed an unimaginable challenge to the healthcare systems worldwide. This online survey captured the impact of the COVID-19 pandemic on nuclear medicine services in Germany comparing 2020 to 2019. MATERIALS AND METHODS: A web-based questionnaire was developed to record the 2020 numbers of nuclear medicine procedures and, in particular, the change compared with 2019. The changes in nuclear medicine diagnostics and therapy were queried, as well as the extent to which "Coronavirus SARS-CoV-2" recommendations provided by the DGN were implemented. RESULTS: 91 complete responses were recorded and evaluated. This corresponds to about 20 % of all German nuclear medicine facilities. Nuclear medicine diagnostic tests showed a decrease in scintigraphies for thyroid (15.9 %), bone (8.8 %), lung (7.6 %), sentinel lymph nodes (5.5 %), and myocardium (1.4 %) with small increases in PET/CT examinations (1.2 %) compared with 2019. Among nuclear medicine therapies, reductions were highest for benign indications (benign thyroid 13.3 %, RSO 7.7 %), while changes from 2019 were less pronounced for malignant indications (PRRT: + 2.2 %, PSMA: + 7.4 %, SIRT: -5.9 %, and RJT for thyroid carcinoma -2.4 %). The DGN recommendations for action were fully or partially applied in 90 %. CONCLUSIONS: The initial significant reduction in nuclear medicine procedures in the first three weeks of the COVID-19 pandemic did not continue, but there was no compensation of the previously not performed services. The decrease in diagnostics and therapy procedures of benign diseases was particularly severe.

[RSO in clinical practice: Status in Germany 2020]. / RSO im klinischen Alltag: Statuserfassung in Deutschland 2020.

BACKGROUND: Radiosynoviorthesis (RSO) is a local radionuclide therapy of inflammatory joint diseases, successfully performed since several decades mainly as an outpatient-protocol in ambulatory health care centers or nuclear medicine practices. Despite of long-term experience in some centers, only very few valuable or comparable data about the procedure itself and/or the clinical results of this treatment are available. OBJECTIVES: The aim of this online survey is to assess reliable data of the current status in Germany. MATERIALS AND METHODS: A web-based questionnaire was designed to evaluate the status of RSO in Germany including demographic data, training, pretherapeutic diagnostics, clinical procedures, and follow-up. The survey was distributed via the supplier of RSO-nuclides, national nuclear medicine societies, and personal networks. It was available for 28 days and closed on November 30, 2020. RESULTS: A total of 78 specialists in nuclear medicine answered the questionnaire, which corresponds to a response rate of 23 %. Several differences and concordances in pre-therapeutic diagnostics, in the procedure of RSO itself, and follow-up were documented in this survey for the first time. Most important, less than 70 nuclear medicine specialists in Germany perform more than 75 % of all RSO-procedures and most of them are older than 50 years of age. This implies the urgent need of a dedicated advancement of young academics in nuclear medicine and a professional advanced training in RSO to offer this beneficial treatment to future patients. CONCLUSIONS: To achieve these goals, an association of RSO experts would be useful, through which, among other things, an RSO training curriculum is developed and theoretical and practical trainings are organized. Moreover, possible cooperation agreements between ambulant and inpatient institutions would foster the education of young nuclear medicine specialists interested in RSO.

Global Impact of COVID-19 on Nuclear Medicine Departments: An International Survey in April 2020.

The coronavirus disease 2019 (COVID-19) pandemic has placed significant challenges on health-care systems worldwide, whether in the preparation, response, or recovery phase of the pandemic. This has been primarily managed by dramatically reducing in- and outpatient services for other diseases and implementing infection prevention and control measures. The impact of the pandemic on nuclear medicine departments and their services has not yet been established. The aim of this online survey was to evaluate the impact of COVID-19 on nuclear medicine departments. Methods: A web-based questionnaire, made available from April 16 to May 3, 2020, was designed to determine the impact of the pandemic on in- and outpatient nuclear medicine departments, including the number of procedures, employee health, availability of radiotracers and other essential supplies, and availability of personal protective equipment. The survey also inquired about operational aspects and types of facilities as well as other challenges. Results: A total of 434 responses from 72 countries were registered and analyzed. Respondents reported an average decline of 54% in diagnostic procedures. PET/CT scans decreased by an average of 36%, whereas sentinel lymph-node procedures decreased by 45%, lung scans by 56%, bone scans by 60%, myocardial studies by 66%, and thyroid studies by 67%. Of all participating centers, 81% performed radionuclide therapies, and they reported a reduction of 45% on average in the last 4 wk, ranging from over 76% in Latin America and South East Asia to 16% in South Korea and Singapore. Survey results showed that 52% of participating sites limited their 99mTc/99Mo generator purchases, and 12% of them temporarily cancelled orders. Insufficient supplies of essential materials (radioisotopes, generators, and kits) were reported, especially for 99mTc/99Mo generators and 131I, particularly in Africa, Asia, and Latin America. Conclusion: Both diagnostic and therapeutic nuclear medicine procedures declined precipitously, with countries worldwide being affected by the pandemic to a similar degree. Countries that were in the postpeak phase of the pandemic when they responded to the survey, such as South Korea and Singapore, reported a less pronounced impact on nuclear medicine services; however, the overall results of the survey showed that nuclear medicine services worldwide had been significantly impacted. In relation to staff health, 15% of respondents experienced COVID-19 infections within their own departments.

Impact of COVID-19 on Nuclear Medicine in Germany, Austria and Switzerland: An International Survey in April 2020.

INTRODUCTION: Preparations of health systems to accommodate large number of severely ill COVID-19 patients in March/April 2020 has a significant impact on nuclear medicine departments. MATERIALS AND METHODS: A web-based questionnaire was designed to differentiate the impact of the pandemic on inpatient and outpatient nuclear medicine operations and on public versus private health systems, respectively. Questions were addressing the following issues: impact on nuclear medicine diagnostics and therapy, use of recommendations, personal protective equipment, and organizational adaptations. The survey was available for 6 days and closed on April 20, 2020. RESULTS: 113 complete responses were recorded. Nearly all participants (97 %) report a decline of nuclear medicine diagnostic procedures. The mean reduction in the last three weeks for PET/CT, scintigraphies of bone, myocardium, lung thyroid, sentinel lymph-node are -14.4 %, -47.2 %, -47.5 %, -40.7 %, -58.4 %, and -25.2 % respectively. Furthermore, 76 % of the participants report a reduction in therapies especially for benign thyroid disease (-41.8 %) and radiosynoviorthesis (-53.8 %) while tumor therapies remained mainly stable. 48 % of the participants report a shortage of personal protective equipment. CONCLUSIONS: Nuclear medicine services are notably reduced 3 weeks after the SARS-CoV-2 pandemic reached Germany, Austria and Switzerland on a large scale. We must be aware that the current crisis will also have a significant economic impact on the healthcare system. As the survey cannot adapt to daily dynamic changes in priorities, it serves as a first snapshot requiring follow-up studies and comparisons with other countries and regions.

An International Survey on Clinical Reporting of PET/CT Examinations: A Starting Point for Cross-Specialty Engagement.

Combined PET/CT imaging has become an integral part of patient management, particularly in oncology. After the imaging examination, a report of the findings is created by expert readers and sent to the referrers as a basis for subsequent decisions. In view of the known wide variation in operational models for PET/CT imaging, we surveyed PET/CT users on their approaches toward PET/CT reporting. Methods: The electronic survey comprised 28 questions on the demographics and professional background of the responders, as well as questions on the structure and quality of PET/CT reports, including the type of reported information, the use of reporting standards, and the mix of reporting standards and expert opinions. The survey was active for 6 wk in early 2018. In total, 242 responses were collected worldwide. Results: The responders were mainly from Europe (78%), with 22% being nuclear medicine specialists, 42% radiologists, 22% dual board-certified, 10% residents in either nuclear medicine or radiology, and 5% medical physicists, radiographers, or oncologists. A slim majority (55%) of responses indicated reports being done according to the European Association of Nuclear Medicine 2015 guidelines for 18F-FDG PET/CT imaging, but 30% of responders were unaware of these guidelines. Report structures varied across sites, with most sites (38%) reporting the PET findings with supplementary localization information from CT, whereas 27% of sites reported along the lines of a CT report with supplementary PET information. One third of the sites included information on the TNM stage of the oncology patient in all reports, whereas 34% and 12% of sites included this information occasionally or only for selected tumors, respectively. For therapy response assessment, various well-established criteria were used. The number of sites utilizing these criteria ranged from 15% (European Organisation for Research and Treatment of Cancer criteria) to 57% (Deauville criteria). Conclusion: Broad variation in the PET/CT reporting strategies adopted for oncology studies and widespread lack of awareness of existing guidelines for PET/CT reporting are evident from responses to this survey, raising concerns as to whether reporting clinicians are optimally using the complementary information from each modality. Greater efforts are needed to ensure harmonization of reporting practices.

[Development of a national competency-based learning objective catalogue for undergraduate medical education in Germany]. / Entwicklung eines kompetenzbasierten Lernzielkatalogs Nuklearmedizin für das Studium der Humanmedizin in Deutschland.

AIMS: Implementation of the guidelines on the Competency-based Learning Objective Catalogue for Undergraduate Medical Education for a Nuclear Medicine curriculum on behalf of the committee on professional training and continuing education of the German Association of Nuclear Medicine (DGN) METHODS:: In 7 domains 100 learning objectives (LOs) were subject to a prioritization in 3 categories (A, B and C) by means of a questionnaire as part of a Delphi method, in collaboration with all members of the DGN holding a "venia legendi" as experts. Category A defined the essential LOs for each medical practitioner. The prioritization was made by ranking the frequency of the A-classifications. In the 2nd step of the Delphi method, a list of LOs with the ranking positions 1-5 in each domain was presented to the first round's experts as a core curriculum, asking either for acceptance or modifications. RESULTS: The results of the 1st step of the Delphi method deliver a return rate of 29% of the questionnaires (55 out of 184). The 2nd round shows a return rate of 30.9% (57 out of 184) and full approval of the proposed LOs in all LO domains by in median 72 % of the experts consulted (61%-81%). The present final version contains 37 competency-based LOs in the LO domains "legal basis and radiation protection", "basic science", indications and contra-indications for "PET/CT", "scintigraphy and SPECT", "patient preparation", "image interpretation" as well as "therapy". CONCLUSION: The Competency-based Learning Objective Catalogue for Nuclear Medicine describes the knowledge and competencies, every physician should have at the end of his medical studies. The LO catalogue is a living document, which needs to be adapted continuously to the progress of the medical and technological development.

99mTc-DPD SPECT/CT for localisation of inflammatory and chronic osteoarthritis of the foot and ankle. Comparison with planar imaging and SPECT as a clinical adjunct in radiosynovectomy.

AIM: The precise localisation of osteoarthritic and inflammatory changes is crucial for selective treatment planning of radiosynovectomy (RSV). The present study evaluated the diagnostic accuracy of planar bone imaging and SPECT for the detection of pathological bone metabolism and inflammation in joints of the foot and ankle, compared with SPECT/CT. PATIENTS, METHODS: 39 patients (mean age 65.6 ± 11.1 years) with suspected inflammatory osteoarthritis underwent SPECT/CT of the feet. After injection of approximately 500 MBq 99mTc DPD, all patients had three-phase planar bone imaging and late-phase hybrid SPECT/CT. late-phase SPECT, and CT of the foot. Increased bone metabolism and blood-pool was assigned to the respective joint of the fore-, mid-, and hindfoot, using SPECT/CT as the reference standard. RESULTS: Overall, SPECT had a higher sensitivity than planar imaging (0.80 vs 0.68, n.s.). The advantage of SPECT was most obvious in the anatomically complex midfoot area (0.63 vs 0.26, p < 0.05) and less obvious in the forefoot (0.85 vs 0.79, n.s.) and hindfoot (0.89 vs 0.89, n.s.). The overall concordance (Cohen`s Kappa) between SPECT/CT and planar (late-phase) imaging and SPECT was high for the forefoot and the hindfoot (planar: 0.78/0.81; SPECT 0.86/0.88) and comparatively low for the midfoot (planar: 0.27; SPECT 0.61). CONCLUSION: SPECT was significantly superior to planar bone imaging for the detection of joint lesions in the midfoot. The differences between SPECT and planar imaging in the fore- and hindfoot were not significant, most likely due to the inherently less complex anatomy. Compared with SPECT alone, a benefit from the use of SPECT/CT can be observed in the midfoot region where it facilitates the identification of the correct joint for RSV.

Pre-therapeutic blood dosimetry in patients with differentiated thyroid carcinoma using 124-iodine: predicted blood doses correlate with changes in blood cell counts after radioiodine therapy and depend on modes of TSH stimulation and number of preceding radioiodine therapies.

OBJECTIVE: Pre-therapeutic blood dosimetry prior to a high-dose radioiodine therapy (RAIT) is recommended and a blood dose of 2 Gy is considered to be safe. In this study, changes in the blood cell count after radioiodine therapy of high risk differentiated thyroid carcinoma (DTC) were analyzed and compared with the results of the pre-therapeutic blood dosimetry using 124I. Moreover, the influence of different modes of TSH stimulation and the number of preceding radioiodine therapies on the blood dose were assessed. METHODS: 198 patients with locally advanced or metastasized DTC received a pre-therapeutic blood dosimetry using 124I. To analyze the influence of the modes of TSH stimulation and the number of preceding RAITs on blood dose subgroups were built as follows: patients with endogenous TSH stimulation versus patients with exogenous TSH stimulation and patients with no preceding RAIT versus patients with at least one preceding RAIT. In 124/198 patients subsequent RAIT was performed. In 73/124 patients, hemograms were performed from day 2 to 12 month after RAIT. RESULTS: There was no high-grade bone marrow toxicity (i.e. ≥ grade 3) in patients receiving less than 2 Gy blood dose-independent of the therapeutic history. Within the first month after radioiodine therapy, there was an overall decrease in the white blood cell and platelet counts. The erythrocyte count was essentially stable. There was a correlation between cell count decrease and predicted blood doses (Spearman's correlation coefficient >-0.6 each) for the white cell line and the platelets. With regard to the subgroups, the blood dose per administered 131I activity (BDpA) was significantly higher in patients with endogenous TSH stimulation (median 0.08 Gy/GBq) than in patients with exogenous TSH stimulation (0.06 Gy/GBq) and in patients with no previous RAIT (0.08 Gy/GBq) compared to patients who had previously undergone at least one RAIT (0.07 Gy/GBq). CONCLUSIONS: The range of BDpA among DTC patients is rather wide. Our results suggest that lower blood doses can be expected when using exogenous TSH stimulation and blood doses are generally higher at first RAIT compared to subsequent RAITs. Thus, we advise to make blood dosimetry standard praxis prior to a high-activity RAIT.

Subjective perception of radiation risk.

Physicians, medical staff, and patients, much like the general population, are becoming increasingly sensitized to the issue of radiation exposure from diagnostic or therapeutic procedures. The attitudes of patients undergoing diagnostic imaging procedures that use ionizing radiation vary widely. Patient perception of radiation dose strongly influences their acceptance of diagnostic examinations or therapies involving radioactivity. Here, we review perceptions and concerns about radiation and radioactivity by laypersons and medical experts. Several studies show that physicians are frequently poorly informed about radiation levels associated with nuclear medicine and radiologic examinations. In addition, patients' decisions against undergoing an imaging procedure are frequently based on partial and sometimes incorrect information. Thus, physicians must take the concerns of their patients seriously. From the literature and our own experience, we conclude that it is extremely important to thoroughly and carefully educate all involved in patient work-up about radiation exposure levels and perceived or actual health risks. Although the choice and timing of imaging examinations should always outweigh the risk that secondary illness will develop, the patients' concerns still must be alleviated.

Clinical applications of 124I-PET/CT in patients with differentiated thyroid cancer.

(124)I-PET/CT has a high clinical potential in patients with differentiated thyroid cancer (DTC). Two aspects deserve special mention: staging of recurrent or residual disease and pretherapy dosimetry. Used in combination (124)I-PET and CT allows foci of highly specific (124)I uptake to be localized with a low radiation dose, which is specifically important in pretherapy diagnostics. In addition in the combination of FDG-PET and CT non-iodine-avid lesions may be detected and may be discriminated from simultaneously occurring iodine-positive lesions. In clinical applications, the pretherapy (124)I-PET dosimetry may result in a significant alteration in the therapeutic procedure compared to standard therapy using fixed therapeutic activities. In this context, (124)I-PET dosimetry is a useful procedure especially in advanced DTC, and allows the administration of safer and more effective radioiodine activities as well as earlier multimodal interventions compared to standard empirical protocols. This review summarizes the clinical data on (124)I-PET/CT in patients with DTC, and addresses future prospects.