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ZusammenfassungUltraschall ist die bildgebende Basisdiagnostik zur Beurteilung der Schilddrüse. Aufgrund der hohen Prävalenz struktureller Parenchymveränderungen kommt das Untersuchungsverfahren in Deutschland sehr häufig zum Einsatz, in vielen Fällen im Rahmen von Verlaufskontrollen. Die Beurteilung thyreoidaler Pathologien und deren Dynamik unterliegt einer relevanten Inter- und Intraobservervariabilität. Befunde die während des Live-Ultraschalls nicht identifiziert und aufgezeichnet wurden, können retrospektiv nicht mehr beurteilt werden. Durch die Akquisition und Dokumentation von standardisierten Videosequenzen der Ultraschallbilder (sogenannte Cine Loops), wird eine sekundäre Nachbetrachtung unter Berücksichtigung von Voraufnahmen analog anderer Schnittbildverfahren wie der CT oder MRT möglich. Die Durchführung könnte dabei auch von nichtärztlichem Personal übernommen werden. Das gewonnene Bildmaterial kann im lokalen PACS gespeichert und für die Lehre und Forschung verwendet werden.

ZusammenfassungDie nuklearmedizinische Ultraschall-Fusionsbildgebung lässt sich unter anderem für die Diagnostik der Schilddrüse und Nebenschilddrüsen klinisch sinnvoll einsetzen und erlaubt die zweifelsfreie räumliche Korrelation metabolischer und morphologischer Informationen. Allerdings beschränkt sich die praktische Anwendung aufgrund derzeit noch limitierender Aspekte auf ausgewählte Fälle und wissenschaftliche Untersuchungen. Die Entwicklung eines integrierten hybriden Detektors zur simultanen nuklearmedizinisch-sonografischen Bildgebung wäre eine Möglichkeit, die bestehenden Limitationen zu überwinden.

In-ovo imaging using ostrich eggs has been described as a potential alternative to common animal testing. The main advantage is its independence from small animal imaging devices as ostrich eggs provide good image quality on regular CT, MRI, or PET used in examinations of humans. However, embryonal motion during dynamic imaging studies produce artifacts. The aims of this study were (1) to explore the feasibility of biomagnetism to detect cardiac signals and embryonal motion and to use these findings (2) to investigate the effect of isoflurane anesthesia on ostrich embryos. A standard magnetoencephalography developed for brain studies was used to detect embryonal signals of ostrich eggs on developmental day 34. Signals were instantly shown on a screen and data were also postprocessed. For assessing the effects of anesthesia, nine ostrich eggs were investigated using isoflurane 6% for 90 min. Biomagnetic signals were recorded simultaneously. A control group consisting of eight different ostrich eggs was also investigated. Cardiac signals similar to electrocardiography were observed in all eggs. Postprocessing revealed frequent motion of embryos without anesthesia. The exposure to isoflurane led to a significant decrease in motion signals in 9/9 ostrich embryos after 8 min. Motion was significantly reduced in the isoflurane group versus control group. There were no isoflurane-related deaths. This study shows that biomagnetism is feasible to detect cardiac signals and motion of ostrich embryos in-ovo. Application of isoflurane is safe and leads to a rapid decrease in embryonal motion, which is an important prerequisite for the implementation of in-ovo imaging using ostrich eggs.

Background: Prostate-specific membrane antigen (PSMA)-directed radioligand therapy (RLT) is a novel treatment for patients with castration-resistant prostate cancer (CRPC). Given the mode of action, patients in an earlier disease stage, such as hormone-sensitive prostate cancer (HSPC), are also likely to benefit from [177Lu]Lu-PSMA- (177Lu-PSMA) or [225Ac]Ac-PSMA-radioligand treatment (225Ac-PSMA). In this retrospective study, we analyzed the safety and efficacy of PSMA-RLT in early-stage and hormone-sensitive metastatic prostate cancer patients. Methods: A retrospective study was performed in patients who received 177Lu-PSMA and/or 225Ac-PSMA with early-stage metastatic prostate cancer. The primary outcome parameter evaluated in this study was the progression-free survival (PFS) after PSMA-RLT and toxicity according to the Common Terminology Criteria for Adverse Events. Secondary outcome parameters were prostate-specific antigen (PSA) response and the date of onset of CRPC state. Results: In total, 20 patients were included of which 18 patients received 177Lu-PSMA radioligand and two patients received tandem treatment with both 177Lu-PSMA and 225Ac-PSMA radioligands. Patients received a median of 2 treatment cycles (range 1–6) and a median activity of 6.2 GBq 177Lu-PSMA per cycle (interquartile range (IQR) 5.2–7.4 GBq). PSMA-RLT was overall well-tolerated. The most common grade 1–2 side effects were xerostomia (n = 6) and fatigue (n = 8), which were only temporarily reported. One patient that received 225Ac-PSMA developed grade 3–4 bone marrow toxicity. The median PFS was 12 months (95% confidence interval (CI), 4.09–19.9 months). Seventeen (85%) patients had a ≥50% PSA response following PSMA-RLT. One patient developed CRPC 9 months following PSMA-RLT. Conclusions: In this small cohort study, PSMA-RLT appeared safe and showed encouraging efficacy for (metastasized) early-stage and hormone-sensitive prostate cancer patients. Prospective studies are awaited and should include long-term follow-up.

The biochemical relapse of prostate cancer is diagnostically challenging but of high clinical impact for subsequent patient treatment. PET/CT with radiolabeled PSMA ligands outperforms conventional diagnostic methods in the detection of tumor recurrence. Several radiopharmaceuticals were and are available for use. The aim of this study was to investigate whether the routinely applied [68Ga]Ga-PSMA ligands PSMA-617, -I&T and -11 (HBED-CC) differ in physiological and pathological distribution, or in tumor detection rate. A retrospective evaluation of 190 patients (39 patients received PSMA-617, 68 patients PSMA-I&T and 83 patients PSMA-11) showed significant differences in tracer accumulation within all organs examined. The low retention within the compartments blood pool, bone and muscle tissue is a theoretical advantage of PSMA-11. Evaluation of tumor lesion uptake and detection rate did not reveal superiority of one of the three radiopharmaceuticals, neither in the whole population, nor in particularly challenging subgroups like patients with very low PSA levels. We conclude that all three [68Ga]Ga-PSMA ligands are equally feasible in this clinically important scenario, and may replace each other in case of unavailability or production restrictions.

A 68-year-old woman was referred with the diagnosis of symptomatic pHPT (primary hyperparathyroidism). Ultrasonography (US) and 99mTc-MIBI scintigraphy could not clearly identify a parathyroid adenoma. A primary unilateral surgical exploration remained unsuccessful to remove adenomatous parathyroid tissue and the pHPT persisted. 18F-ethylcholine PET/CT showed a left-sided retropharyngeal lesion with intense tracer uptake that could not be detected on US images at first sight. Therefore, additional 18F-ethylcholine PET/US fusion imaging was performed and revealed a poorly definable nodular structure on US that could be unambiguously correlated to the PET finding. Surgical excision confirmed an oncocytic variant of parathyroid adenoma, and parathormone and calcium levels normalized immediately.

To proof the feasibility of manufacturing patient-indivdual (anthropomorphic) thyroid replicas from I-124 PET DICOM datasets by means of 3D printing. A possible field of application is the use of those phantoms for the calibration of gamma probes. After editing of the DICOM datasets using several software types and transferring into a dedicated stereolithography format, 10 fillable thyroid replicas (35-200 mL) made of polylactide acid were manufactured via 3D printing. All replicas were filled with a water-solution containing 3.5 MBq I-131 and applied to a standard neck phantom. Calibration factor measurements were carried out using a clinical gamma probe. Measurements were performed with three different tilts: + 15°, 0° and -15°. The influence of the replicas' volume and the tilt was investigated. Manufacturing of the replicas was successful in all cases. The time required for data processing was 13 ± 2 (median: 12, range: 9-25) min and 4-11 h for 3D printing (size-dependent). The printing process could be done overnight. Measured mean calibration factor for straight gamma probe positioning (0° tilt) was 31 965 ± 3360 (33 893, 25 470-34 253) cpm/MBq. A tilt of -15° resulted in lower calibration factors (-7.7 %), whereas a tilt of + 15° led to higher values (+ 9.5 %); p = 0.001. The calibration factors were highly inversely proportional correlated to the volume of the replicas (r = -0.91, p 0.001). 3D printing of patient-individual (anthropomorphic) fillable thyroid replicas was feasable for a large range of volumes. The study demonstrates the influence of the volume as well as the tilt of the measured object for calibration factor measurements with gamma probes.ZIEL: Diese Studie adressiert die Herstellung von patientenspezifischen (anthropomorphen) Schilddrüsenrepliken aus I-124-PET-DICOM-Datensätzen mittels eines handelsüblichen 3D-Druckers. Als mögliches Anwendungsgebiet wurden diese Phantome zur Kalibrierung von Gammamesssonden eingesetzt. Nach Aufbereitung der DICOM-Datensätze mittels mehrerer unterschiedlicher Computerapplikationen und Übertragung der Daten in ein spezielles Stereolithografie-Format, wurden 10 füllbare Schilddrüsenrepliken (Volumen: 35–200 ml) im 3D-Druckverfahren hergestellt. Alle Repliken wurden mit einer Wasserlösung (inklusive 3,5 MBq I-131) befüllt und in ein standardisiertes Halsphantom eingebracht. Es wurden Kalibrierfaktoren unter Verwendung einer klinischen Gammamesssonde ermittelt. Die Messungen wurden mit 3 verschiedenen Neigungen der Sonde durchgeführt: + 15°, 0° und –15°. Der Einfluss des Replikatvolumens und der Gammasondenneigung auf den Kalibrierungsfaktor wurde berechnet. Die Herstellung der Repliken war in allen Fällen erfolgreich. Die für die Datenverarbeitung erforderliche Zeit betrug 13 ± 2 (Median: 12, Bandbreite: 9–25) Minuten und 4–11 Stunden für den 3D-Druck (größenabhängig). Der 3D-Druck konnte über Nacht erfolgen. Der Kalibrierfaktor betrug bei gerader Sondenpositionierung (0° Neigung) 31 965 ± 3360 (33 893, 25 470–34 253) cpm/MBq. Eine Neigung von –15° führte zu niedrigeren Kalibrierfaktoren (–7,7 %), während eine Neigung von + 15° höhere Werte ergab (+ 9,5 %; p = 0,001). Es zeigte sich eine starke umgekehrte Proportionalität der Kalibrierfaktoren zum Volumen der Schilddrüsenrepliken (r = –0,91; p 0,001). Der 3D-Druck von patientenindividuellen (anthropomorphen) Schilddrüsenreplikaten war für eine große Bandbreite an Volumina möglich. Die Studie demonstrierte den Einfluss der Schilddrüsenvolumina sowie des Neigungswinkels auf die Messung von Kalibrierfaktoren mittels Gammasonden.

To investigate the value of I-124 positron emission tomography (PET) / ultrasound (US) fusion imaging in comparison to conventional diagnostics (CD) of Thyroid nodules (TN) by multiple observers. Digital patient case files (PCF) of patients that received CD and I-124-PET/US in clinical routine were prepared containing cine-loops of the examinations. All physicians with nuclear medicine specialty from Germany, Austria, and Switzerland were invited to participate. 106 acquired observers completed 7.2 ± 1.8 (median: 8, range: 4-14) randomly assigned PCF (CD only or CD+PET/US). They assessed the TN function, stated their confidence in functional assessment, and suggested a treatment course for each TN. 68 PCF of 34 patients comprising 66 TN ≥ 1 cm (= 1.94 TN/patient) were created. A total of 748 (11.2/TN), and 751 ratings (11.4/TN) were recorded for CD only, and CD+PET/US, respectively. The functional assessment revealed more hyper- or hypofunctioning (524 vs. 320, p 0.0001) and less indifferent or not rateable (209 vs. 428, p 0.0001) TN in CD+PET/US vs. CD only. The observers' confidence in functional assessment was superior in CD+PET/US (p 0.0001). Furthermore, the ratings were carried out more homogeneous in CD+PET/US (p 0.0001). Fewer suggestion of follow up (p 0.0001), and more (p 0.0001) suggestion of invasive treatments (fine-needle aspirationsurgery) was observed in CD+PET/US. Radioiodine therapy was more often (p = 0.0036), and thyroid medication less often (p = 0.0167) advised in CD+PET/US. Functional assessment of equivocal TN shows frequent failures in CD, underestimating the incidence of hyper- and hypofunctioning lesions. Confidence in functional assessment significantly increases with additional PET/US. This influences the proposed treatment course.ZIEL: Multi-Observer-Untersuchung des diagnostischen Mehrwerts der I-124-Positronenemissionstomografie (PET)/Ultraschall (US) -Fusionsbildgebung im Vergleich zur konventionellen Diagnostik (CD) bei der Funktionsbeurteilung von Schilddrüsenknoten. Es erfolgte die Erstellung digitaler Patientenakten inklusive Filmsequenzen von Probanden, die im Rahmen der klinischen Routine sowohl mittels CD als auch I-124-PET/US untersucht wurden. Alle nuklearmedizinischen Ärzte aus Deutschland, Österreich und der Schweiz waren zur Teilnahme eingeladen. 106 Untersucher absolvierten jeweils 7,2 ± 1,8 (Median: 8, Bandbreite: 4–14) randomisiert zugewiesene digitale Patientenakten (CD oder CD+PET/US). Sie beurteilten die Funktion der Schilddrüsenknoten, ihre subjektive Sicherheit bei der Funktionsbeurteilung und schlugen einen Behandlungsverlauf vor. 68 digitale Patientenakten von 34 Patienten mit 66 Schilddrüsenknoten ≥ 1 cm (= 1,94 Knoten pro Patient) wurden erstellt. Insgesamt wurden 748 Bewertungen (11,2 pro Knoten) für CD und 751 Bewertungen (11,4 pro Knoten) für CD+PET/US dokumentiert. Bei CD+PET/US wurde die Funktion der Knoten im Vergleich zu CD häufiger als hyper- oder hypofunktionell (524 vs. 320; p 0,0001) und seltener als indifferent oder nicht bewertbar (209 vs. 428; p 0,0001) beurteilt. Die subjektive Sicherheit der Untersucher war bei CD+PET/US höher (p 0,0001) und die Funktionsbeurteilungen wurden mit größerer Homogenität abgegeben (p 0,0001). Bei CD+PET/US wurden im Vergleich zu CD weniger Verlaufskontrollen (p 0,0001), mehr invasive Behandlungen (FeinnadelaspirationOperation) (p 0,0001), häufiger Radioiodtherapien (p = 0,0036) und seltener medikamentöse Therapien (p = 0,0167) empfohlen. Die Funktion von Schilddrüsenknoten wird in der konventionellen Diagnostik häufig falsch beurteilt. Der Anteil hyper- oder hypofunktioneller Läsionen wird unterschätzt. Die subjektive Sicherheit bei der Funktionsbeurteilung steigt durch den Einsatz der I-124-PET/US. Diese Ergebnisse beeinflussen die vorgeschlagenen Behandlungsverläufe.

Fusion imaging with nuclear medicine and ultrasound via mobile handheld gamma cameras has been recently introduced, however a phantom for the registration accuracy of this fusion approach is still lacking. We developed a hybrid phantom, consisting of poly-methyl methacrylate and exchangeable ultrasound (US) compatible windows made of silicone or poly-vinyl chloride. A standard balloon catheter, filled with a mixture of [99mTc]TcO4 and water, was positioned at the center of the water-filled phantom. This approach enabled an objective measurement of the registration accuracy.

Purpose FDG PET/CT has been described for noninvasive grading, detection of extrahepatic spread, and recurrence in hepatocellular carcinoma (HCC). As compared with localized imaging approaches (MRI, ultrasonography), FDG PET/CT not only focuses on the liver, but covers a long field of view from the base of the skull to the thighs, visualizing pathologic findings not related to HCC. The aims of this retrospective study were to (1) describe the frequency of relevant incidental findings on FDG PET/CT in HCC patients, (2) evaluate the impact on treatment strategy in HCC patients considered for liver transplantation, and (3) to discuss the role of FDG PET/CT in patients considered for transplantation in general. Methods Four hundred thirty-nine FDG PET/CT examinations of 345 HCC patients were screened for incidental findings. The clinical information system was searched for examinations performed after FDG PET/CT and aimed at verification of incidental findings. Of 345 HCC patients, 81 patients were considered for liver transplantation. The impact of incidental findings was recorded separately for this subgroup. Results One hundred one patients with incidental findings in 439 FDG PET/CT examinations were identified. The incidental findings comprised 22 neoplasms (9 malignant) and 52 inflammations. Liver transplantation was not performed because of an incidental finding on FDG PET/CT in 9 (11.1%) of 81 patients. Conclusions FDG PET/CT is capable of identifying relevant incidental findings (ie, secondary malignancy, benign tumors, and inflammation) in HCC patients and HCC patients considered for liver transplantation and thus influencing HCC patient management. FDG PET/CT might also be beneficial in patients considered for transplantation of different organs.

Aims: To investigate the feasibility and accuracy of 3D-US extended field of view volumetric analyses acquired with mechanically-swept ultrasound probes with different measurement methods for large volume thyroid phantoms.Materials and methods: Fifteen thyroid phantoms with different shapes (regular, nodular, thickened isthmus) and volumes (50-400 mL) were created. Two different mechanically-swept US probes were used for the separate scanning of the left and right lobes: convex and linear probe. After specific modifications, the 3D-US datasets were stitched together to an extended field of view using predefined landmarks. Volumetric analyses were performed by conventional ellipsoid model and manual tracing methods. The correspondence of measured and reference volumes was calculated using Pearson’s correlation coefficients and limits of agreement according to Bland and Altman.Results: The C-probe proved feasible for the acquisition and processing of the three-dimensional ultrasound extended field of view images; very high levels of agreement (correlation coefficients for volume analyses: 0.9843-0.9992) were observed for all shapes and volumes investigated. The manual tracing method showed superior results in comparison to the ellipsoid model, but was more time consuming. The linear probe was only applicable for the 50 mL phantoms due to its limited field of view.Conclusions: The investigated mechanically-swept convex probe was suitable for the three-dimensional ultrasound extended field of view stitching of large volume thyroid phantoms. Accurate volume analyses could be carried out. The mechanically-swept linear probe is limited to a maximum of 50 m

Intravenous radionuclide therapies are gaining importance. With the increased frequency of these therapies, safe application procedures in combination with effective radiation protection are needed. We present a shielded system which can be universally used for the application of liquid radiopharmaceuticals. The application system consists of a cuboidal box made of lead with stainless steel coating, an inner layer of polymethyl methacrylate (PMMA), a disposable line/bottle system, and a medical infusion pump. No proprietary disposable parts are used. The system was tested and validated ex-vivo, and evaluated for Lu-177 peptide receptor radionuclide and for radioligand therapies (PRRT, RLT). Construction of the application system was performed in accordance with the physical characteristics of the used isotopes. 10 validation procedures with 1 GBq Tc-99m-pertechnetate confirmed functionality. 38 PRRT and 13 RLT procedures were performed successfully and completely. At least 98 % of the prescribed activities were infused. No leakage of radioactivity occurred. Dose rate measurements showed that the radiation in the box is shielded completely, and that exposure arises only from the infusion line outside the box and from the patient. The presented application system for intravenous radionuclide therapies is feasible, safe, and cost-efficient. It has been shown that Lu-177-PRRT and -RLT can be performed without complications while ensuring nearly complete infusion of the prescribed radiopharmaceutical dose. Radiation exposure of the applying physician and other staff is low. The construction of the shielding box ensures complete shielding of all radionuclides currently used for radiomolecular therapies.ZIEL: Intravenöse Radionuklidtherapien gewinnen an Bedeutung. Mit der zunehmenden Häufigkeit dieser Therapien sind sichere Applikationsverfahren in Kombination mit einem wirksamen Strahlenschutz erforderlich. Wir präsentieren ein abgeschirmtes System, das universell für flüssige Radiopharmazeutika eingesetzt werden kann. Das Applikationssystem besteht aus einer quaderförmigen Box aus einer Bleilegierung mit Edelstahlbeschichtung, einer inneren Schicht aus Polymethylmethacrylat (PMMA, Plexiglas), einem Einweg-Schlauch-/Flaschensystem und einer Infusionspumpe ohne proprietäre Einwegteile. Das System wurde ex vivo getestet und validiert. Der praktische Einsatz erfolgte bei Lu-177-Peptid-Radiorezeptor- und bei Radioliganden-Therapien (PRRT, RLT). Das Applikationssystem wurde unter Berücksichtigung der physikalischen Eigenschaften der verwendeten Isotope konstruiert. 10 Validierungsprozeduren mit je 1GBq Tc-99m-Pertechnetat bestätigten die Funktionalität. 38 PRRT und 13 RLT wurden erfolgreich durchgeführt. Mindestens 98 % der Ausgangsaktivität wurden infundiert. Es trat keine Leckage von Radioaktivität auf. Radioaktive Strahlung aus dem Inneren der Box wird vollständig abgeschirmt. Eine Strahlenexposition geht nur von der Infusionsleitung außerhalb der Box und vom Patienten aus. Das vorgestellte Applikationssystem ist funktionell, sicher und kostengünstig. Lu-177-PRRT und -RLT konnten ohne Komplikationen mit nahezu vollständiger Infusion der therapeutischen Aktivität durchgeführt werden. Die Strahlenexposition des applizierenden Arztes und des übrigen Personals ist gering. Die Konstruktion der Abschirmbox gewährleistet eine vollständige Abschirmung aller derzeit für radiomolekulare Therapien verwendeten Radionuklide.

Renal function and effective half-life (t1/2,eff) of I-131 have not been fully elucidated in patients undergoing radioiodine therapy (RAIT) for differentiated thyroid cancer (DTC). Aim of the present analysis was to evaluate the potential of cystatin C-based estimated glomerular filtration rate (eGFRCysC) in comparison to conventional creatinine (eGFRCrea) and to verify which methods to determine t1/2,eff are most accurate to predict t1/2,eff. Forty-eight patients receiving whole-body I-131-scintigraphy were included. eGFRCysC was compared to eGFRCrea with regard to accuracy of t1/2,eff prediction. Three different methods (i.e. blood-based, gamma camera-based and probe-based) and two protocols with either three (short period,SP; up to 42 h) or four (long period,LP; up to 114 h) time points were compared using the Akaike’s information criterion. The eGFRCysC measurement is more likely than eGFRCrea in predicting the t1/2,eff. High correlation coefficients were found between t1/2,eff assessed by gamma camera and probe measurements and blood-based determination revealed lower values. Patients with normal eGFR showed higher values of t1/2,eff of LP compared to SP. eGFRCysC should be included in further study protocols. As camera and probe measurements lead to almost superimposable results, one of the methods is expendable. Blood-based results of t1/2,eff were lower, presumably due to unspecific iodine retention, whereas the lower correlation with renal function may be caused by individual differences in intestinal iodine resorption. SP-protocols up to 42 h after I-131 administration are sufficient to determine t1/2,eff. Further studies are necessary for specific recommendations regarding I-131 activity reduction during RAIT in patients with DTC and renal insufficiency.

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

In ovo studies are a valuable option in preclinical research, but imaging studies are severely limited by the costs of dedicated equipment needed for small-sized eggs. We sought to verify the feasibility of using larger, ostrich, eggs (Struthio camelus) for imaging on the PET/CT scanners used for routine clinical investigations. Methods: Ostrich eggs were incubated until shortly before hatching, prepared for intravitelline venous injection of contrast medium or radiotracer, and imaged using native CT, contrast-enhanced CT, and PET/CT. Any technical adaptations that were needed to improve the outcome were noted. Results: Of the 34 eggs initially incubated, 12 became fully available for imaging of embryonal development. In ovo imaging with conventional PET/CT not only was feasible but also provided images of good quality, including on dynamic PET imaging. Conclusion: In ovo imaging with ostrich eggs and routine clinical scanners may allow broader application of this field of preclinical research, obviating costly dedicated equipment and reducing the number of animals needed for classic animal research. Further experiments are warranted to refine this novel approach, especially to reduce motion artifacts and improve monitoring of viability.

The purpose of this study is to investigate I-124 positron emission tomography (PET)/ultrasound (US) fusion imaging for function assessment of thyroid nodules. In 70 patients, 201 lesions were examined with conventional diagnostics (CD) (thyroid US, laboratory findings and Tc-99m pertechnetate scintigraphy), Tc-99m pertechnetate single photon emission computed tomography (SPECT) and I-124 PET/computed tomography (CT). Subsequently, US fusion imaging (SPECT/US and PET/US) was performed by three experienced investigators. Patients referred for thyroid diagnostics in a clinical routine setting were included in this study if CD produced equivocal results. PET/US was superior to CD and SPECT/US in 96% and 86%, respectively, and ambiguous findings in CD were clarified by PET/US in 96% of the 70 patients. Regarding nodule-based function assessment, 10% (66%), 39% (14%) and 71% (4%) of the 201 lesions were rated with absolute certainty (equivocal or uncertain) using CD, SPECT/US and PET/US, respectively (p < 0.001). PET/US has the potential to improve the function assessment of thyroid nodules in comparison to CD.

SummaryBackground and objectives : 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) frequently reveals incidental findings. The present study focused on incidental FDG-PET/CT findings in cutaneous melanoma patients, and verified their relevance with respect to further diagnostic measures and interventions. Patients and methods : Medical records of 181 consecutive melanoma patients were retrospectively evaluated to verify the management of incidental findings, with particular emphasis on histological findings. Results : Thirty-three of 181 (18 %) patients showed 39 relevant incidental findings, located in the colorectal tract (n = 15 patients), thyroid (n = 8), prostate (n = 2), locomotor system (n = 2), lymph nodes (n = 2), parotid gland (n = 1), tonsils (n = 1), kidneys (n = 1), and gallbladder (n = 1). Performed in 25 patients, additional diagnostic procedures revealed a clinical correlate in 21 cases. Sixteen of 21 patients had tumoral involvement, including five malignant lesions (four colorectal and one prostate carcinoma). The malignancies were diagnosed at an early stage, and successfully removed in the majority of cases. Conclusions : The diagnostic use of FDG-PET/CT is routinely recommended for stage IIC melanoma and higher, and is widely accepted as indication. This study effectively identified otherwise undetected cancers, especially colorectal malignancies. Early interventions were possible in most cases. Incidental findings on FDG-PET/CT should be worked up with appropriate diagnostic measures, considering the patient's condition and wishes.

HINTERGRUND UND ZIELE Bei der (18) F-Fluordeoxyglucose-Positronenemissionstomographie/Computertomographie (FDG-PET/CT) ergeben sich haufig Zufallsbefunde. In der vorliegenden Studie konzentrierten wir uns auf mittels FDG-PET/CT erhaltene Zufallsbefunde bei Patienten mit kutanem Melanom und uberpruften deren Relevanz hinsichtlich weiterer diagnostischer Masnahmen und Interventionen. PATIENTEN UND METHODEN Die Krankenakten von 181 konsekutiven Melanom-Patienten wurden retrospektiv ausgewertet, um das Management von Zufallsbefunden zu dokumentieren. Der Schwerpunkt lag dabei auf den histologischen Befunden. ERGEBNISSE Bei 33 von 181 (18 %) Patienten lagen 39 relevante Zufallsbefunde vor, und zwar im Kolorektalbereich (n = 15 Patienten), in der Schilddruse (n = 8), der Prostata (n = 2), dem Bewegungsapparat (n = 2), in Lymphknoten (n = 2), der Parotis (n = 1), den Mandeln (n = 1), den Nieren (n = 1) und der Gallenblase (n = 1). Bei 25 Patienten schlossen sich weitere diagnostische Verfahren an, wobei in 21 Fallen ein klinisches Korrelat nachgewiesen wurde. Bei 16 von 21 Patienten ergab sich eine Neoplasie, darunter funf maligne Lasionen (vier Kolonkarzinome und ein Prostatakarzinom). Die Malignome wurden fruhzeitig diagnostiziert und in der Mehrzahl der Falle erfolgreich entfernt. SCHLUSSFOLGERUNGEN Der Einsatz der FDG-PET/CT als Routine-Diagnostik wird in den Leitlinien empfohlen und ist indiziert bei malignem Melanom ab Stadium IIC. In dieser Studie wurden auf effektive Weise ansonsten nicht erkannte Krebserkrankungen, insbesondere Kolonkarzinome, detektiert. In den meisten Fallen war eine fruhe Intervention moglich. Zufallsbefunde durch FDG-PET/CT sollten, unter Berucksichtigung des Zustands und der Wunsche des Patienten, mit den geeigneten diagnostischen Masnahmen abgeklart werden.

This study aimed to assess a hypothetical minimum administered activity of (124)I required to achieve comparability between pretherapeutic radioiodine uptake (RAIU) measurements by (124)I PET/CT and by (131)I RAIU probe, the clinical standard. In addition, the impact of different reconstruction algorithms on (124)I RAIU and the evaluation of pixel noise as a parameter for image quality were investigated.Different scan durations were simulated by different reconstruction intervals of 600-s list-mode PET datasets (including 15 intervals up to 600 s and 5 different reconstruction algorithms: filtered-backprojection and 4 iterative techniques) acquired 30 h after administration of 1 MBq of (124)I. The Bland-Altman method was used to compare mean (124)I RAIU levels versus mean 3-MBq (131)I RAIU levels (clinical standard). The data of 37 patients with benign thyroid diseases were assessed. The impact of different reconstruction lengths on pixel noise was investigated for all 5 of the (124)I PET reconstruction algorithms. A hypothetical minimum activity was sought by means of a proportion equation, considering that the length of a reconstruction interval equates to a hypothetical activity.Mean (124)I RAIU and (131)I RAIU already showed high levels of agreement for reconstruction intervals of as short as 10 s, corresponding to a hypothetical minimum activity of 0.017 MBq of (124)I. The iterative algorithms proved generally superior to the filtered-backprojection algorithm. (124)I RAIU showed a trend toward higher levels than (131)I RAIU if the influence of retrosternal tissue was not considered, which was proven to be the cause of a slight overestimation by (124)I RAIU measurement. A hypothetical minimum activity of 0.5 MBq of (124)I obtained with iterative reconstruction appeared sufficient both visually and with regard to pixel noise.This study confirms the potential of (124)I RAIU measurement as an alternative method for (131)I RAIU measurement in benign thyroid disease and suggests that reducing the administered activity is an option. CT information is particularly important in cases of retrosternal expansion. The results are relevant because (124)I PET/CT allows additional diagnostic means, that is, the possibility of performing fusion imaging with ultrasound. (124)I PET/CT might be an alternative, especially when hybrid (123)I SPECT/CT is not available.

Aims: Thyroid volume has to be measured in goiters prior to radioiodine treatment to calculate the needed amount of radioactivity. Modern clinical equipment for ultrasonography shows the trend to smaller probes, so that larger goiters do not fit any longer into the probe’s field of view. This study evaluated the feasibility and accuracy of stitching procedures applied to thyroid volumetric analysis performed using three-dimensional ultrasound (3D-US).Material and methods: Ad hoc thyroid phantoms of different shapes (regular, nodular, thickened isthmus) and volumes (ranging between 50 and 400 mL) were developed. In 15 such phantoms the left and right lobes were separately scanned, and the 3D-US datasets were then assembled (stitched) using predefined landmarks and dedicated software. Volumetric analysis was then assessed via a conventional ellipsoid model (em) and manual tracing (mt). The correlation of measured and reference volumes was determined using Pearson’s correlation coefficients and Bland and Altman limits of agreement.Results: The results showed a high level of agreement (with correlation coefficients ranging from 0.974 to 0.999) for all shapes and volumes tested, including the largest volume of 400 mL. The mt method, although more time consuming, proved superior to the em.Conclusions: Stitching-mediated thyroid volumetric analysis is accurate, and its clinical performance should be investigated in future studies

Renal function and effective half-life (tForty-eight patients receiving whole-body I-131-scintigraphy were included. eGFRThe eGFReGFR

Side-by-side evaluation of thyroid ultrasound (US) and 99mTcO4 scintigraphy can lead to uncertainties in the correct topographic assignment of thyroid nodules. The aim of this study was to evaluate 99mTcO4 single-photon emission computed tomography/ultrasound (SPECT/US) fusion imaging. Seventy-nine patients were prospectively investigated. If conventional diagnostics of the thyroid gland (B-mode-US, scintigraphy) produced unclear findings, SPECT was performed and transferred to a US device for real-time sensor-navigated 3-D fusion US investigation. The data sets were manually matched according to their contours. Finally, SPECT/US versus conventional diagnostics was rated using an ordinal 4-point scale (SPECT/US >> conventional diagnostics, SPECT/US > conventional diagnostics, SPECT/US = conventional diagnostics, SPECT/US >, >) in 84% and equivalent (=) in 16% of the cases, respectively. No statistically significant differences were observed for uni-, bi- and multinodular goiters (p ≥ 0.3). In 67%, the respective problem that arose after conventional diagnostics was clarified by SPECT/US. SPECT/US was feasible and was helpful for the clarification of uncertain functionality assessments of thyroid nodules.

The purpose of this study is to compare functional MR urography (MRU) with the results of ultrasound and radionuclidePediatric patients with proven congenital anomalies of the kidney and urinary tract were included (n = 112). The morphologic findings of MRU were compared with previous diagnostic ultrasound findings. For evaluation of split renal function and urinary tract obstruction, MAG3 scintigraphy was used as a reference standard.MRU provided detailed morphologic information of the whole urinary tract for all 112 patients. In 94.6% of cases (n = 106), diagnostic findings could be verified, and in 5.4% of cases (n = 6), more detailed information could be gained. Equivalent split renal function showed good concordance between functional MRU and MAG3 scintigraphy. However, in kidneys with restricted function (35%), functional MRU underestimated the remaining renal function, with a mean difference of 6.6% and an SD of 24.4%. For evaluation of relevant urinary tract obstruction, the sensitivity of functional MRU was 100%, specificity was 81.6%, positive predictive value was 70.8%, and negative predictive value was 100%.Regarding split renal function, functional MRU shows a lack of accuracy in comparison with the clinical standard MAG3 scintigraphy, especially in patients with severely diminished function of one kidney. However, functional MRU allows an adequate assessment of urinary tract obstruction and a high-resolution morphologic evaluation of the whole urinary tract. Thus, functional MRU is suitable to add diagnostic value, especially as a complementary examination for complex individual cases in the presurgical state.

Circulating epithelial tumor cells (CEC) are the link between the primary tumor and distant metastases. Only few studies have been performed investigating the role of CEC in patients with differentiated thyroid carcinoma. CEC can be detected in patients with DTC and metastases as well as patients with benign thyroid diseases, raising the question of CEC origin. Single cell analyses of CEC show that mRNA typical for thyroid tissue can be found in part of the CEC; therefore, thyroid origin is highly probable. Considering the influence of RIT on the number of CEC, there are patients in which patterns can be identified, presuming a destruction of CEC following RIT. The experiences presented in this book chapter are based on a limited number of patients and served as pilot studies to establish the method of CEC detection in DTC patients; therefore, its use in clinical routine cannot be recommended yet. Further studies are required to investigate the clinical performance of this method.

The objective of this study was to assess the radiation exposure of the investigators' hand during free-hand single photon emission tomography/ultrasound ((99m)TcO4-fhSPECT/US) of the thyroid. Conventional dosimetry by rings with thermoluminescent detectors (TLDs) was performed in 32 patients (Group A), followed by TLD-chipstrate dosimetry in further 20 patients (Group B). In both the groups, the ambient dose rate was measured by dose rate meter (DRM). The applied activity was in the range of 60-80 MBq (99m)TcO4. In Group A, the exposure per investigation was 7.53 µSv (calculated average) by ring dosimetry and 9.02±5.64 µSv by DRM; in Group B, 10.93 and 9.51 ± 1.76 µSv, respectively. Based on estimated 1224 yearly thyroid investigations per nuclear medicine specialist in Germany, the estimated cumulative yearly exposure of the hand was 11.32 mSv. The hand exposure during a thyroid (99m)TcO4-fhSPECT/US of 20-min duration proved modest and comparable with different methods. Yearly examinations in excess of 1000 per investigator are not expected to add a relevant cumulative risk.

Summary 18F-fluorodeoxyglucose positron emission tomography (FDG-PET)/CT is commonly used to assess tumour recurrence in high-risk patients with malignant melanoma (MM). However, results can be ambiguous either because of the CT's insufficient soft-tissue contrast or non-specific FDG accumulation caused by inflammation. Ultrasound (US) can provide additional morphologic information that is superior to CT. For precisely combining PET and US findings, we used a real-time fusion technique based on navigated US (PET/US fusion). Here, we describe our results from patients where PET/US fusion proved helpful in differentiating unclear PET/CT findings. This fusion technique is likely to be helpful for decision making in MM patients and biopsy guidance.

The aim of this study is to determine whether circulating epithelial cells (CEC) detected in patients with differentiated thyroid cancer (DTC) stem from the thyroid gland. CEC have been described to increase in patients with progressive cancer disease and thus have been used as a marker of tumour cell dissemination. CEC were selected from venous blood samples of five DTC patients and analysis of thyroid-specific mRNA (i.e. Tg, TSH-R, TPO, NIS) was performed on a single cell level. 16/48 cells were positive for at least three different thyroid-mRNA transcripts, predominantly found in patients with detectable serum thyroglobulin. In conclusion, evidence was found that in patients with detectable serum thyroglobulin, most of the CECs originate from the thyroid gland. However, further investigations including a larger sample size are needed to validate the clinical impact of this method.

A 65-year-old woman presented with increased human thyroglobulin (3.3 ng/mL) 5 years after resection of a papillary thyroid carcinoma and successful I radioiodine therapy. I whole-body scintigraphy showed a small focus ventrally in the right lower neck, leading to suspicion of a papillary thyroid carcinoma recurrence. I-PET/CT and real-time PET/US fusion matched to a small hypoechoic/anechoic ovoid structure situated between the right sternoclavicular joint and the brachiocephalic trunk. After surgical resection, histology allowed a diagnosis of thymic cyst. A follow-up I whole-body scintigraphy showed no residual iodine accumulation.

To assess the radiation exposure of the investigator during navigated fusion of nuclear medicine images with ultrasound after application of I-124. Dosimetry with two different types of thermoluminescent detectors (TLD) was performed in 25 patients. The dose rate at the patient's neck was measured with a calibrated dose rate meter (DRM) and served as the standard of reference. The average exposure per investigation at the patient's neck measured by LiF:Mg,Cu,P TLDs (cumulative: 212 μSv), LiF:Mg,Ti TLDs (cumulative: 112 μSv) and DRM (cumulative: 150.3 μSv). The radiation exposure of the hand during navigated fusion of nuclear medicine imaging with 124I and ultrasound with a mean duration of 13 min is low and comparable between different methods. Yearly examinations are not expected to add a relevant cumulative risk.

PURPOSE This study aimed at investigating the performance of late I PET/CT for radioiodine uptake (RAIU) measurement at 336 hours after administration in patients with benign thyroid diseases requiring radioiodine therapy. Special attention was paid to the comparability of I uptake (I-RAIU) to the clinical standard (I-RAIU, probe measurement). Considering cost aspects, we sought to establish an economically reasonable examination protocol based on scan duration and administered activity. METHODS List-mode PET data sets of 40-minute acquisition time were acquired 336 hours after administration of 1 MBq I in 18 patients. Different scan durations were simulated by different reconstruction intervals (RIs) ranging from 5 seconds to 40 minutes, and total thyroid activity was measured. Mean I-RAIU levels of each RI were compared with mean I-RAIU levels (3 MBq). A hypothetical scan duration or hypothetical activity, respectively, was sought by means of a proportion equation, considering that the length of an RI is equitable to a hypothetical activity. RESULTS After 336 hours, the mean total thyroid activity was 254 ± 7.7 kBq for I and 26.9 ± 8.7 kBq for I. The mean I-RAIU and I-RAIU showed high levels of agreement for RI from 2 minutes to 40 minutes. Reconstruction interval shorter than 2 minutes did not result in sufficient agreement. CONCLUSIONS The present study confirmed the feasibility of late I PET/CT as alternative method for RAIU measurement in patients with benign thyroid diseases; 1 MBq I PET/CT scans as short as 2 minutes resulted in RAIU levels comparable to those of standard I-RAIU. The parameter "appropriate scan-duration activity product" is proposed to enable an economically reasonable examination protocol.

To detect hypervascularized liver lesions, early dynamic (ED) 18F-FDG PET may be an alternative when contrast-enhanced (CE) imaging is infeasible. This retrospective pilot analysis compared contrast between such lesions and liver parenchyma, an important objective image quality variable, in ED PET versus CE CT. Twenty-eight hypervascularized liver lesions detected by CE CT [21 (75 %) hepatocellular carcinomas; mean (range) diameter 4.9 ± 3.5 (1–14) cm] in 20 patients were scanned with ED PET. Using regions of interest, maximum and mean lesional and parenchymal signals at baseline, arterial and venous phases were calculated for ED PET and CE CT. Lesional/parenchymal signal ratio was significantly higher (P

This concept might be another step toward development of an integrated hybrid imaging technique analogous to PET/CT, SPECT/CT, and PET/MR imaging.

Radioiodine therapy of benign thyroid diseases requires pretherapy assessment of radioactive iodine uptake (RAIU) for reliable therapy planning.Our objective was to assess RAIU by low-activity (124)I-positron emission tomography/low-dose computed tomography ((124)I-PET/CT) in comparison with standard (131)I probe measurements.This prospective comparative study was conducted at the Jena University Hospital, Jena, Germany, in a referral center setting.A total of 79 patients with benign thyroid diseases were screened, 40 of whom met the inclusion criteria (stable TSH, free T3 and free T4 levels; no thyroid-specific medication, no iodine contamination) and 24 of whom agreed to participate by signing an informed consent.All patients received the standard (131)I scintillation probe uptake test 30 hours after administration of 3 MBq (131)I. Seven days later, all patients were subjected to (124)I-PET/CT uptake measurement 30 hours after administration of 1 MBq (124)I.The decay-corrected uptake values of both techniques were compared. Additionally, 3 different volume-of-interest-based evaluation methods in PET/CT (whole neck [WN], automatic isocontour [IC], and manually contoured [MC]) were evaluated.The (131)I probe measurement and (124)I-PET.WN method provided very similar mean RAIU (30.7% ± 10.3%; 31.7% ± 8.9%), resulting in a significant positive correlation (r = 0.93, P.001). Compared with (124)I-PET.WN, the (124)I-PET.IC (29.8% ± 8.6%) and the (124)I-PET.MC (24.5% ± 7.1%) demonstrated lower uptake values.Using activities as low as 1 MBq, the (124)I-PET.WN method shows a good correlation with conventional (131)I probe measurement. Thus, (124)I-PET/CT is a suitable alternative for pretherapy RAIU evaluations. This may offer potential additional benefits such as PET/ultrasound fusion imaging and CT volumetry.

The aim of this pilot study was to investigate the changes of circulating epithelial cells in the blood of patients with differentiated thyroid cancer after radioiodine-therapy with I-131. The cells were detected by fluorescence-microscopy via the epithelial-cell-adhesion-molecule (EpCAM), a molecule described to be over-expressed in most carcinoma tissues and also present on circulating cells deriving from primary site. Epithelial cells were assessed before radioiodine-therapy, as well as 2 days, 14 days, and 3 months after therapy. 2 patient groups were examined: 1) patients with thyroid cancer receiving a first radioiodine-therapy after thyroidectomy (RITfirst, n=13), and 2) patients with thyroid cancer in need of repeated radioiodine-therapy due to local or metastatic recurrences (RITrep, n=15). Circulating epithelial cell changes were correlated to changes of serum-thyroglobulin and to clinical response evaluated 3 months after therapy. Patients with an early decrease of cells after radioiodine-therapy (RITfirst 7/13; RITrep 2/15) showed an increase of serum-thyroglobulin in most of the cases (RITfirst 5/7; RITrep 2/2). In the RITrep group, a decrease in cell counts 2 days after radioiodine-therapy indicated a clinical response in 90% of the cases. This study indicates that the number of circulating epithelial cells in differentiated thyroid cancer undergo changes in response to radioiodine-therapy. The destruction of cells through radioiodine-therapy may induce a short-term release of thyroglobulin in the blood. A clear relationship between the clinical outcome and the cell changes could not be found, but early cell decreases may help identifying patients more likely to respond to radioiodine-therapy.

This study investigates whether early dynamic positron emission tomography/computed tomography (edPET/CT) using (18)F-sodium fluoride-((18)F-NaF) is feasible in depicting early phases of radiotracer distribution in patients with chronic osteomyelitis (COM).A total of 12 ed(18)F-NaF-PET/CT examinations were performed on 11 consecutive patients (2 female, 9 male; age 53 ± 12 years) in list mode over 5 min starting with radiopharmaceutical injection before standard late (18)F-NaF-PET/CT. Eight consecutive time intervals (frames) were reconstructed for each patient: four 15 s, then four 60 s. Several volumes of interest (VOI) were selected, representing the affected area as well as different reference areas within the bone and soft tissue. Maximum and mean ed standardized uptake values (edSUVmax, edSUVmean, respectively) were calculated in each VOI during each frame to measure early fluoride influx and accumulation. Results were compared between affected and non-affected (contralateral) bones.Starting in the 31-45 s frame, the affected bone area showed significantly higher edSUVmax and edSUVmean compared to the healthy contralateral region. The affected bone areas also significantly differed from non-affected contralateral regions in conventional late (18)F-NaF-PET/CT.This pilot study suggests that, in patients with COM, ed(18)F-NaF -PET offers additional information about early radiotracer distribution to standard (18)F-NaF -PET/CT, similar to a three-phase bone scan. The results should be validated in larger trials which directly compare ed(18)F-NaF-PET to a three-phase bone scan.

Evaluation of thyroid ultrasound and Tc-pertechnetate scintigraphy side by side frequently produces ambiguous results regarding the correct assignment of anatomy and functionality of a nodule. We describe the usefulness of Tc-pertechnetate-SPECT/US-fusion imaging. A 75-year-old woman was referred for exclusion of cold nodules. After conventional diagnostics (in vitro thyroid parameters, B mode-US, planar Tc-pertechnetate-thyroid scintigraphy), a SPECT was performed using a conventional gamma camera. The SPECT data set was transferred to an ultrasound device (LOGIQ E9), and sensor-navigated 3D ultrasound was performed. Both data sets (SPECT/US) were fused in real time, revealing the exact functional state of multiple nodules.

Summary Aim: This retrospective study sought to investigate the relationship between biological half-life (t 1/2 biol ) of 131I and estimated glomerular filtration rate (eGFR) in patients with thyroid carcinoma. Patients, methods: 96 patients with differentiated thyroid carcinoma (69 women, 27 men, mean age 64.0 ± 13.6 years) and diagnostic and therapeutic administration of 131I were considered. Patients with pronounced specific iodine storage were not included in the study. The eGFR was estimated according to the Chronic Kidney Disease Epidemiology Collaboration (CKDEPI) formula, the t 1/2 biol via dosimetry. Patients were subdivided in groups with normal clearance (NC) (n = 37, 38.5%), medium clearance (MC) (n = 48, 50.0%), and low clearance (LC) (n = 11, 11.5%) (eGFR _ 90; 60-89; 15-59 ml/min per 1.73 m2, respectively). The relationship between eGFR and t 1/2 biol of 131I was modeled using a power function. Results: The groups significantly differed in terms of age (NC 53.8, MC 68.6, and 78.0 years, respectively), serum creatinine levels (NC: 0.71; MC: 0.85; LC: 1.18 mg/dl), and t 1/2 biol (NC: 0.53; MC: 0.71; LC: 1.01 days). The t 1/2 biol was significantly influenced only by eGFR, and not by age, gender, or body weight. The relationship between t 1/2 biol of 131I and eGFR was described by the formula t 1/2 biol = 20.3 · eGFR−0.782. Conclusions: The calculated relationship between renal function and t 1/2 biol of 131I can be used in principle to estimate a dose reduction for patients with renal insufficiency. The model, however, gives erroneous results in individual cases and therefore a routine utilization cannot be recommended. Prospective studies are necessary, based on larger patient numbers and more accurate methods for dose rate measurement and GFR.

Bei der (18) F-Fluordeoxyglucose-Positronenemissionstomographie/Computertomographie (FDG-PET/CT) ergeben sich häufig Zufallsbefunde. In der vorliegenden Studie konzentrierten wir uns auf mittels FDG-PET/CT erhaltene Zufallsbefunde bei Patienten mit kutanem Melanom und überprüften deren Relevanz hinsichtlich weiterer diagnostischer Maßnahmen und Interventionen.Die Krankenakten von 181 konsekutiven Melanom-Patienten wurden retrospektiv ausgewertet, um das Management von Zufallsbefunden zu dokumentieren. Der Schwerpunkt lag dabei auf den histologischen Befunden.Bei 33 von 181 (18 %) Patienten lagen 39 relevante Zufallsbefunde vor, und zwar im Kolorektalbereich (n = 15 Patienten), in der Schilddrüse (n = 8), der Prostata (n = 2), dem Bewegungsapparat (n = 2), in Lymphknoten (n = 2), der Parotis (n = 1), den Mandeln (n = 1), den Nieren (n = 1) und der Gallenblase (n = 1). Bei 25 Patienten schlossen sich weitere diagnostische Verfahren an, wobei in 21 Fällen ein klinisches Korrelat nachgewiesen wurde. Bei 16 von 21 Patienten ergab sich eine Neoplasie, darunter fünf maligne Läsionen (vier Kolonkarzinome und ein Prostatakarzinom). Die Malignome wurden frühzeitig diagnostiziert und in der Mehrzahl der Fälle erfolgreich entfernt.Der Einsatz der FDG-PET/CT als Routine-Diagnostik wird in den Leitlinien empfohlen und ist indiziert bei malignem Melanom ab Stadium IIC. In dieser Studie wurden auf effektive Weise ansonsten nicht erkannte Krebserkrankungen, insbesondere Kolonkarzinome, detektiert. In den meisten Fällen war eine frühe Intervention möglich. Zufallsbefunde durch FDG-PET/CT sollten, unter Berücksichtigung des Zustands und der Wünsche des Patienten, mit den geeigneten diagnostischen Maßnahmen abgeklärt werden.

(18) F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) frequently reveals incidental findings. The present study focused on incidental FDG-PET/CT findings in cutaneous melanoma patients, and verified their relevance with respect to further diagnostic measures and interventions.Medical records of 181 consecutive melanoma patients were retrospectively evaluated to verify the management of incidental findings, with particular emphasis on histological findings.Thirty-three of 181 (18 %) patients showed 39 relevant incidental findings, located in the colorectal tract (n = 15 patients), thyroid (n = 8), prostate (n = 2), locomotor system (n = 2), lymph nodes (n = 2), parotid gland (n = 1), tonsils (n = 1), kidneys (n = 1), and gallbladder (n = 1). Performed in 25 patients, additional diagnostic procedures revealed a clinical correlate in 21 cases. Sixteen of 21 patients had tumoral involvement, including five malignant lesions (four colorectal and one prostate carcinoma). The malignancies were diagnosed at an early stage, and successfully removed in the majority of cases.The diagnostic use of FDG-PET/CT is routinely recommended for stage IIC melanoma and higher, and is widely accepted as indication. This study effectively identified otherwise undetected cancers, especially colorectal malignancies. Early interventions were possible in most cases. Incidental findings on FDG-PET/CT should be worked up with appropriate diagnostic measures, considering the patient's condition and wishes.