An international survey on hybrid imaging: do technology advances preempt our training and education efforts?

BACKGROUND: Hybrid PET/CT and PET/MRI are increasingly important technologies in the evaluation of malignancy and require cooperation between radiologists and specialists in molecular imaging. The aim of our study was to probe the mindsets of radiological and nuclear medicine professionals in regard to current hybrid imaging practice and to assess relevant training aspirations and perceived shortfalls, particularly amongst young professionals. In this context, we initiated an international survey on "Hybrid Imaging Training". METHODS: An online survey was prepared on-line and launched on October-2, 2016. It was composed of 17 multiple-choice and open questions regarding the professional background, a perspective on hybrid imaging training efforts and lessons to be learned from disparate craft groups. The survey ran for 2 weeks. We report total responses per category and individual free-text responses. RESULTS: In total, 248 responses were collected with a mean age of all responders of (41 ± 11) y. Overall, 36% were within the target age range of (20-35) y. Across all responders, the majority (72%) commented on there being too few hybrid imaging experts in their country, whereas only 1% said that there were too many. Three quarters of the responders were in favour of a curriculum allowing sub-specialisation in hybrid imaging. With respect to reporting of hybrid imaging, confidence increased with age. The average rating across all responders on the level of cooperation among the two specialties suggested a low overall level of satisfaction. However, the survey feedback indicated the local (on-site) cooperation being somewhat better than the perceived cooperation between the relevant associations on a European level. CONCLUSION: We consider these results to represent an appropriate cross-section of professional opinions of imaging experts across different demographic and hierarchical levels. Collectively they provide evidence supporting a need to address current shortfalls in developing hybrid imaging expertise through national educational plans, and, thus, contribute to helping improve patient care.

Radioiodine therapy of metastatic lesions of differentiated thyroid cancer.

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

Variations of clinical SPECT/CT operations: an international survey.

AIM: This survey gathers information about clinical SPECT/CT operations worldwide to help guide standardization of clinical SPECT/CT imaging. METHODS: An international, web-based survey of SPECT/CT users was initiated in 12/2010 through an e-mail distribution. Users were asked 71 questions related to (A) demographics, (B) SPECT/CT operations/utilization and (C) variations in imaging protocols. RESULTS: Collected responses originated from 117 imaging centers in the Americas (66%), Europe (20%), Asia-Pacific (11%) and the Middle-East (3%), with the majority of responding sites representing public health care institutions (69%). Most sites operate 1-2 SPECT/CT-systems (74%), typically installed in Nuclear Medicine departments (84%) with extensive prior SPECT-only experience (82%). Only 14% of SPECT/CTs are installed in Radiology departments. Clinical SPECT/CT imaging is performed either as routine (51%) or ad-hoc "add-on" procedure (49%) with a high inter-site and inter-examination variability. The main application of the integrated CT is to provide anatomical localization of the tracer uptake rather than to produce contrast-enhanced or other high-quality CT images. Consequently, in only 22% of the sites a CT contrast injector is installed. Only 6% of centers use SPECT/CT devices for stand-alone CT procedures. CONCLUSION: An international survey among clinical SPECT/CT users revealed that SPECT/CT is a not a routine component of nuclear medicine procedures. The majority of the centers responding do not fully utilize the diagnostic potential of the CT components. Significant variations in standard imaging protocols were observed. These findings illustrate the need for training and standardization and underscore the need for revisiting the role of SPECT/CT in diagnostic imaging.

[Nuclear medicine in Europe: education]. / Nuklearmedizin in Europa. Die Ausbildungssituation.

The technical developments that have taken place in the preceding years (PET, hybrid imaging) have changed nuclear medicine. The future cooperation with radiologists will be challenging as well as positioning nuclear medicine in an European context. It can also be expected that education in nuclear medicine will undergo a harmonization process in the states of the European Union. In this paper, we describe how nuclear medicine education is organized in several European countries. We aim to stimulate constructive discussions on the future development of the specialization in nuclear medicine in Germany.

[Scintigraphically "hot" thyroid nodules mainly go hand in hand with a normal TSH]. / Szintigraphisch mehranreichernde Schilddrüsenknoten gehen überwiegend mit normwertigem TSH einher.

AIM: In recent years, various professional societies published guidelines for diagnostic evaluation of thyroid nodules, in which the indication for scintigraphy is restricted to patients with subnormal TSH values. It is seen controversial whether such recommendations should be transferred to Germany, partly because of lower iodine intake in this country and the consequent higher percentage of autonomous thyroid nodules, which are not accompanied by a measurable dysfunction. Since reliable data to this topic are scarce, we analyzed multicentrically the spectrum of scintigraphically "hot" and "warm" nodules under the current epidemiological conditions. PATIENTS, METHODS: In 10 German nuclear medicine out-patient institutions we evaluated the diagnostic data from a total of 514 patients, in whom unequivocally hyperfunctional nodules (focal increased uptake in comparison to perinodular tissue with a sonographically nodular correlative ≥1 cm) could be detected by (99m)Tc-pertechnetate scintigraphy. To minimize selection bias, the surveys were not carried out in hospitals.The recorded parameters included the thyroid hormone levels, the global (99m)Tc-uptake (TcTU), the size of each nodule and the total autonomous nodular volume (V(aut)). RESULTS: Only 20% of the patients with "hot" nodules had subnormal TSH levels (<0.1 to 0.33 mU / l), the remaining patients had TSH levels from 0.34 to 3.5 mU /l (in one third of the patients TSH levels even exceeded 1.0 mU/l). Moreover, we found no relevant correlation between TSH and TcTU or V(aut). CONCLUSIONS: In Germany, in at far the largest proportion of patients with autonomous thyroid nodules objectified by means of scintigraphy, TSH levels are within the normal range. Since such nodules with maximum safety can be classified as benign, a corresponding scintigraphic finding has a high priority for the patient. These current data support that it is not reasonable to restrict scintigraphy to patients with subnormal TSH values in this country.

Quantitative imaging of (124)I with PET/ CT in pretherapy lesion dosimetry. Effects impairing image quantification and their corrections.

Iodine-131-labelled agents are successfully used in cancer treatment. In the pretherapy dosimetry approach, positron emission tomography/computed tomography (PET/CT) using (124)I provides a modality to estimate absorbed dose to tumours and can be considered as the preferred imaging method for this purpose in (131)I radiopharmaceutical therapies. For accurate dosimetry, serial measurements of activity concentrations (ACs) over an appropriate time period are necessary. Consequently, accurate AC determination is of paramount importance in PET/CT-based lesion dosimetry using (124)I-labelled agents. After presenting an historical overview of (124)I clinical application, this review focuses on factors impairing PET image quantification accuracy and on methods of correcting for these effects. Specifically, the emission of prompt gamma photons in the (124)I decay process that are detected in coincidence with each other and with the annihilation photon, and the low (124)I positron branching ration of only 23% raise concerns regarding image quantification accuracy. This review discusses this prompt gamma effect, its impact and approaches to correct for this phenomenon. In (124)I lesion dosimetry, recovery coefficients (RCs) are commonly used to compensate primarily for partial-volume effect but also, in a simplistic way, for prompt gamma coincidence effect; the main methodological factors affecting the RC-corrected (124)I AC are described. Finally, special issues in image (124)I quantification are reviewed, including coadministration of high therapeutic activities of 131I, shine-through artefact, and transmission-contamination effect occurring in stand-alone PET systems.

[E-learning in nuclear medicine - a nationwide survey in Germany]. / E-Learning in der Nuklearmedizin: Eine Erhebung an deutschen Universitäten.

AIM: To assess available e-learning concepts and programmes for nuclear medicine at university hospitals in Germany. METHODS: All (34) departments of nuclear medicine at German university hospitals were asked to participate in an anonymized online survey. Questions were categorized into four topics: 1.) clinic and education; 2.) on-site strategies for e-learning; 3.) available e-learning offers and 4.) free text comments on experiences and expectations. All input was reviewed descriptively; free text was analyzed analytically. RESULTS: The response rate was 56% (19/34). 13/19 responses indicated well-defined e-learning strategies, mainly to support frontal teaching courses. Future e-learning perspectives focus on clinical case studies with sufficient imaging materials. Only 7/19 university hospitals operate a centralized e-learning platform (e. g. Moodle). The acceptance of the available e-learning options by the students is considered relatively poor. CONCLUSIONS: Today e-learning concepts for nuclear medicine are available at selected university hospitals only. All responders wish to expand on e-learning but many report the lack of administrative support to do so. These data could be regarded as a basis for discussions of inter-university teaching scenarios.

Thyroid remnant dose: 124I-PET/CT dosimetric comparison of rhTSH versus thyroid hormone withholding before radioiodine remnant ablation in differentiated thyroid cancer.

AIM: Recombinant human thyroid-stimulating hormone (rhTSH) recently was approved as an alternative to thyroid hormone withholding (THW) to elevate TSH for thyroid remnant ablation in differentiated thyroid carcinoma patients. High ablation success rates are reported with diverse rhTSH-aided (131)I activities. Improved renal function causes approximately 50% faster radioiodine clearance under euthyroidism versus hypothyroidism. Knowledge of comparative remnant radioiodine kinetics, particularly the remnant radiation dose in Gy/GBq of administered (131)I activity (RDpA), could assist in choosing rhTSH-aided ablative activities. MATERIAL AND METHODS: To compare the RDpA, determined through (124)I-positron emission tomography/computed tomography (PET/CT), under the two stimulation methods, we retrospectively divided into two groups 55 consecutive totally-thyroidectomized, radioiodine-naïve patients. The rhTSH group (n=16) received (124)I on thyroid hormone, 24 h after two consecutive daily intramuscular injections of rhTSH, 0.9 mg. The THW group (n=39) received (124)I after weeks-long THW, when serum TSH first measured > or = 25 mIU/L. We performed PET investigations 4 h, 24 h, 48 h, 72 h and 96 h and PET/CT 25 h after (124)I administration. RESULTS: Median stimulated serum thyroglobulin was 15 times higher (p=0.023) and M1 disease almost twice as prevalent (p=0.05) in rhTSH versus THW patients. Mean+/-standard deviation RDpA was statistically equivalent between the groups: rhTSH, 461+/-600 Gy/GBq, THW, 302+/-329 Gy/GBq, two-sided p=0.258. CONCLUSIONS: rhTSH or THW deliver statistically equivalent radiation doses to thyroid remnant and may be chosen based on safety, quality-of-life, convenience and pharmacoeconomic factors. Institutional fixed radioiodine activities formulated for use with THW need not be adjusted for rhTSH-aided ablation.

[Impact of nuclear medicine imaging techniques for lymph node surgery]. / Bedeutung der nuklearmedizinischen Bildgebung für die Lymphknotenchirurgie.

Nuclear medicine imaging techniques allow the noninvasive in vivo visualization of cellular and subcellular molecular processes. In the context of lymph node surgery and patient management in uro-oncology, two molecular nuclear imaging techniques deserve special interest: positron emission tomography (PET) for staging, restaging, and follow-up, and preoperative identification and subsequent biopsy of the sentinel lymph node (the first lymph node in the lymphatic drainage system of the tumor). Both methods and their clinical potential are described in this review. Future trends in molecular imaging in uro-oncology are also discussed.

Whole-body PET/CT-mammography for staging breast cancer: initial results.

The purpose of this study was to evaluate the feasibility and utility of a dedicated positron emission tomography (PET)/CT protocol in breast cancer patients. 40 patients with suspected recurrent breast cancer underwent whole-body PET/CT in the supine position (SP) followed by PET/CT of the breasts and axillae in the prone position (PP) using a special positioning aid. PP and SP images were compared in terms of the tumour-to-thoracic-wall distance, tumour-to-skin distance and tumour volume, diameter, density, maximal standardized uptake value (SUV(max)) and localization. The size of axillary areas, the number of intra-axillary lymph nodes, their transverse diameters, their SUV(max) and the number of distant metastases were compared between PP and SP images. Differences were tested for significance using the Student's t-test. All patients tolerated PP imaging well. Five locally recurrent breast cancers were detected, both in the SP and in the PP. Mean tumour-to-thoracic-wall distances (PP, 19 mm; SP, 8 mm; p = 0.003) and tumour-to-skin distances (PP, 10 mm; SP, 7 mm; p = 0.013) were significantly larger in the PP than in the SP. Potential thoracic wall or skin infiltration, as well as quadrant localization, were determined more easily in PP. The axillary area was wider in the PP when compared with SP (PP, 14.4 cm(2); SP, 10.6 cm(2); p<0.001). No other parameters were significantly different. In conclusion, a dedicated whole-body PET/CT examination, including PET/CT mammography, is feasible for clinical practice and may offer important information on the possible infiltration of a breast lesion into the adjacent thoracic wall and skin. Even though the axilla may be delineated more clearly in the PP, there seems to be no benefit with regard to N-staging.

Somatostatin receptor scintigraphy in advanced renal cell carcinoma. Results of a phase II-trial of somatostatine analogue therapy in patients with advanced RCC.

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

Combined metabolic and morphologic imaging in thyroid carcinoma patients with elevated serum thyroglobulin and negative cervical ultrasonography: role of 124I-PET/CT and FDG-PET.

PURPOSE: This study sought to compare iodine-124 positron emission tomography/computed tomography (124I-PET/CT) and 2-[18F]fluoro-2-deoxy-D: -glucose- (FDG-) PET in the detection of recurrent differentiated thyroid carcinoma (DTC) lesions in patients with increasing serum thyroglobulin (Tg), Tg-antibodies, or both, but without pathological cervical ultrasonography. We assessed the lesion detection accuracy of 124I-PET alone, CT alone, (124)I-PET/CT, FDG-PET, and all these modalities combined. MATERIAL AND METHODS: The study included 21 patients (9 follicular, 12 papillary DTC) who had been rendered disease-free by thyroidectomy and radioiodine treatment (RIT) and followed up for 21-275 months after the last RIT. In all patients, FDG-PET was performed first. Within 1 week, 124I-PET/CT was performed 24 h after oral administration of 43 +/- 11 MBq 124I. Imaging results were correlated with further clinical follow-up with (n = 12) or without (n = 9) post-study histology as the reference standard. RESULTS: The sensitivities for DTC lesion detection were: 124I-PET, 49%; CT, 67%; 124I-PET/CT, 80%; FDG-PET, 70%; and all modalities combined, 91%. For local recurrences (distant metastases), the sensitivities were: 124I-PET, 60% (45%); CT, 20% (84%); and FDG-PET, 65% (71%). One-third of lesions demonstrated pathological tracer uptake with both 124I- and FDG-PET, while two-thirds were positive with only one of these modalities. CONCLUSION: Used together, 124I-PET and CT allow localization of foci of highly specific 124I uptake as well as non-iodine-avid lesions. The combination of 124I-PET/CT and FDG-PET improves restaging in recurrent DTC by enabling detection on whole-body scans of local recurrence or metastases that are often not found if only one of the methods or other imaging modalities are applied.

Cancer of unknown primary.

FDG-PET has been proven to be very sensitive in detecting a large variety of carcinomas. The FDG accumulation in malignant tumors is quite stereotyped and often reflects the aggressiveness of the tumor. Therefore, FDG appears to be suitable to detect unknown primaries independent of the type of disease. Being unaware of the site of the primary and also being unaware of the intensity of glucose metabolism, the interpretation of FDG-PET images needs rules accepting a reduced specificity for the definition of malignancy. However, due to physiological FDG-uptake in the head and neck area, especially in lymphatic tissue and vocal cords, one has to accept a high rate of equivocal findings interpreting FDG-PET alone. In this situation, the use of dual-modality PET/CT is of particular value. It allows for correlating the suspicious or unclear PET finding directly with morphology and by that the rate of false-equivocal or false-positive findings is reduced. In addition, PET/CT can precisely define the site of the PET finding in terms of anatomy, helping to direct the surgeon. This characteristic is of different value depending on the location of the primary and tends to be of utmost importance in the head and neck area. Finally, CT by itself may contribute with the detection of PET-negative findings. Thus in conclusion, PET and PET/CT can help localize the primary in CUP in approximately 40% of all cases, even after a thorough work-up with a variety of other investigations.

124-iodine positron emission tomography/computed tomography dosimetry in pediatric patients with differentiated thyroid cancer.

AIM: Publications on 124-iodine (124I-)-positron emission tomography/computed tomography (PET/CT) dosimetry contain few if any data on pediatric patients with differentiated thyroid carcinoma (DTC). Aim of our study is to determine safety and informativeness of 124I-PET/CT dosimetry in DTC patients2Gy blood dose portending serious myelotoxicity. RESULTS: Besides hypothyroid fatigue, no symptoms were noted. In 4 dosimetry procedures before the first radioiodine therapy, RDpAs were generally high (median 288 Gy/GBq, range 59-648 Gy/GBq). LDpAs (4 lymph node metastases) were much lower (median 6.5 Gy/GBq, range 1-9 Gy/GBq). CBAs were high (median 26 GBq, range 19-42, n=5). Disease management was modified or disease extent clarified in 2/4 patients. CONCLUSIONS: A standard adult 124I-PET/CT dosimetry protocol appears to be safe and informative in pediatric DTC patients.

Cervical lymph node metastases of unknown origin: primary tumor detection with whole-body positron emission tomography/computed tomography.

BACKGROUND: Identification of primary tumor in patients with cervical lymph node metastasis of unknown primary (MUO) has a great impact on therapy approach and potentially on patient prognosis. PURPOSE: To assess the diagnostic accuracy of combined positron emission tomography(PET)/computer tomography (CT) for primary tumor detection in cervical metastases of unknown origin compared to PET, CT, and PET+CT side-by-side evaluation. MATERIAL AND METHODS: 39 consecutive patients (eight women, 31 men; mean age 59.9 ± 11.2 years) with MUO were enrolled in this study. PET/CT images were obtained 1 hour after injection of 350 MBq of fluorodeoxyglucose. Oral and intravenous contrast agents were administered in all patients to ensure diagnostic CT data. Fused PET/CT data were evaluated for primary tumor detection. Diagnostic accuracy was calculated and compared with CT alone, PET alone, and side-by-side PET+CT evaluation.Statistical analysis of differences in diagnostic performance between the different imaging procedures was based on the McNemar test. RESULTS: Fused PET/CT depicted the primary tumor in 11 of 39 (28%) patients. In 28(72%) patients, the primary tumor remained occult. CT revealed the primary in five(13%), PET alone in 10 (26%), and side-by-side evaluation of PET+CT in 10 (26%) of 39 patients. Statistical analysis showed no significant differences between the imaging modalities. CONCLUSION: PET, side-by-side PET+CT, and PET/CT revealed similar detection rates for primary tumors in cervical MUO patients. Therefore, cervical metastases of an unknown primary may be assessed with either of these imaging modalities. Detection rates with CT were substantially lower. Thus, inclusion of functional data for assessment of cervical MUO patients must be recommended.

124I-PET dosimetry in advanced differentiated thyroid cancer: therapeutic impact.

PURPOSE: This study evaluated the impact of (124)I-positron emission tomography (PET) dosimetry on post-primary surgery therapy in radioiodine-naïve patients with advanced differentiated thyroid cancer (DTC). PATIENTS, MATERIAL, METHODS: In each of 28 thyroidectomized patients with high-risk DTC (one or more of pT4, pN1 or pM1), we gave 23-50 MBq of (124)I as an oral capsule and performed PET dosimetry to calculate the individualized therapeutic (131)I activity that would, insofar as possible, achieve a radioiodine dose >or=100 Gy to all metastases without exceeding 2 Gy to the blood (a surrogate for bone marrow toxicity). We thus determined the absorbed lesion dose per GBq of administered 131I activity (LDpA) based on serial PET (4, 24, 48, 72 and 96 h after oral 124I intake) and PET/computed tomography (25 h after (124)I intake) and the critical blood activity (CBA) based on blood and whole-body radiation counting (2, 4, 24, 48, 72, 96 h after 124I intake). We compared the dosimetry-based interventions with our standard empirical protocol. RESULTS: 25 patients had a total of 126 iodine-positive metastases. 18 (72%) of the 25 had solely iodine-avid metastases, while seven (28%) had both iodine-avid and -non-avid metastases. In two patients (8%), none of the iodine-avid metastases could have been practically treated with a sufficient radiation dose. Relative to the empirical protocol, (124)I-PET dosimetry findings changed management in 7 (25%) patients, e.g. allowing application of activities >11 GBq (131)I. Further changes included implementation of hematological back-up in a patient found to be at risk of life-threatening marrow toxicity, and early multimodal therapy in 9 (32%) patients. CONCLUSION: 124I-PET dosimetry is a useful routine procedure in advanced DTC and may allow safer or more effective radioiodine activities and earlier multimodal interventions than do standard empirical protocols.