[Technical innovations to optimize ultrasound imaging]. / Technische Innovationen zur Optimierung der Ultraschallbildgebung.

Due to the high incidence of thyroid disease, ultrasound examination of the neck has high priority in many nuclear medicine departments. A precise sonogram with high spatial resolution and image sharpness over the entire imaging area, combined with minimal artifacts, is the prerequisite for meeting the demand for high diagnostic accuracy in modern medicine. In the last 20-30 years, a number of significant technical innovations have been implemented, such as the development of the matrix array, electronic image focusing, realtime compound imaging, artifact limitation by speckle reduction and harmonic imaging, as well as the possibility to extend the field of view.

[Normal values for adult thyroid volume on ultrasound - where do they come from and how should they be evaluated?] / Sonographische Normwerte für das Schilddrüsenvolumen Erwachsener ­ woher kommen sie und wie sind sie zu bewerten?

The upper limit for the thyroid volume is 18 ml for women and 25 ml for men. These reference values are used and taught in many clinics and practices across several disciplines. The thyroid volume is a relevant factor for the treatment course. But where do the standard values for thyroid volumes come from, what kind of studies have been carried out to establish them? Should these upper limits be used as an universal standard in clinical routine, and which factors can influence the physiological organ size? The following article is dedicated to a critical review of the commonly used reference values for the thyroid volume of adults.

[Standardized acquisition and documentation of cine loops on conventional thyroid ultrasound]. / Standardisierte Akquisition und Dokumentation von Videosequenzen bei der konventionellen Schilddrüsensonografie.

Ultrasound is the basic imaging method for the assessment of the thyroid gland. Due to the high prevalence of structural disease, the examination procedure is used very frequently in Germany, in many cases in the context of follow-up. The assessment of thyroid pathologies and their dynamics is subjected to relevant inter- and intraobserver variability. Findings that were not identified during live ultrasound cannot be assessed retrospectively. Applying an SOP for the acquisition and documentation of standardized video sequences of ultrasound images (so-called cine loops), allows for a secondary retrospective evaluation of the thyroid gland, taking into account previously acquired images analogous to other cross-sectional imaging methods such as CT or MRI. The cine loops can be acquired by non-physician personnel, stored to the local PACS and used for educational and research purposes.

Radioembolization With Holmium-166 Polylactic Acid Microspheres: Distribution of Residual Activity in the Delivery Set and Outflow Dynamics During Planning and Treatment Procedures.

PURPOSE: To evaluate the microsphere outflow dynamics and residual Ho-166 activity during and after transarterial radioembolization planning and treatment procedures, and to assess the distribution and predilection sites of residual activity in the proprietary delivery set and the microcatheter. MATERIALS AND METHODS: Fifteen planning and 12 therapeutic radioembolization procedures were performed with poly-l-lactic acid microspheres loaded with Ho-166. The amount and distribution of residual activity was assessed by dose calibrator measurements and SPECT imaging. The activity flow profile from the microcatheter was assessed dynamically. For planning procedures, different injection methods were evaluated in order to attempt to decrease the residual activity. RESULTS: The median residual activities for planning and treatment procedures using standard injection methods were 31.2% (range 17.3%-44.1%) and 4.3% (range 3.5%-6.9%), respectively. Planning residual activities could be decreased significantly with 2 injection methods similar to treatment procedures, to 17.5% and 10.9%, respectively (P = 0.002). Main predilection sites of residual microspheres were the 3-way stopcock and the outflow needle connector. During treatment procedures, more than 80% of the injected activity is transferred during the first 3 injection cycles. CONCLUSION: After treatment procedures with holmium-loaded microspheres, mean residual activity in the delivery set is reproducibly low and between reported values for glass and resin microspheres. The majority of microspheres is transferred to the patient during the second and third injection cycle. An estimated residual waste of 3% to 4% may be included in the treatment activity calculation. For planning procedures, a modified injection technique should be used to avoid high residual activities.

Update on diagnosis and treatment of hyperthyroidism: ultrasonography and functional imaging.

Ultrasonography and radionuclide imaging using [99mTc]Pertechnetate or radioactive iodine isotopes are essential tools used during the diagnostic workup of hyperthyroidism with or without structural alterations of the thyroid. Color duplex sonography and ultrasound elastography may add important information to find the cause of the hormone excess. During the last few years, hybrid imaging using SPECT/-(CT) or PET-based methods, such as [124]Iodine-PET/CT or [124]Iodine-PET/ultrasound have been increasingly used, playing a role in the context of localizing ectopic thyroid tissue or in multinodular goiter. Recently, promising data has been published on the use of [99mTc]MIBI imaging in amiodarone induced hyperthyroidism.

Transarterial Radioembolization with Yttrium-90 Glass Microspheres: Distribution of Residual Activity and Flow Dynamics during Administration.

PURPOSE: To evaluate the microsphere flow dynamics and residual yttrium-90 (90Y) activity during and after transarterial radioembolization with glass microspheres and to assess the distribution and predilection sites of residual activity in the administration devices. MATERIALS AND METHODS: In this laboratory investigation, after 18 consecutive clinical transarterial radioembolization and 4 ex vivo experimental procedures with 90Y glass microspheres, the distribution of residual activity in the administration devices was assessed by activimeter and positron emission tomography (PET)/CT measurements. During ex vivo procedures, microsphere outflow from the administration device was assessed by dynamic scintigraphic measurements. RESULTS: Mean residual activity was 3.4% ± 1.7 (range, 0.9%-8.8%). Calculations showed a negative correlation between relative residual activity and prescribed activity (r = -0.4258, P = .0486) and a positive correlation between absolute residual activity and prescribed activity (r = 0.5345, P = .0104). The main predilection site was the Luer-Lok microcatheter connector. Lower activities were detected in the dose vial. Flow measurements showed that more than 98% of the final injected activity was transferred to the patient with the first 20 mL of saline solution. CONCLUSIONS: Residual activity in the standard administration device for glass microsphere radioembolization is considered to be low compared with similar procedures, but is variable. The microsphere flow profile shows an initial peak, resulting in a rapid activity transfer at the beginning of the injection process. The findings may have implications for safe handling of the administration device and for dose calculation of 90Y glass microspheres.

Renal and Intestinal Excretion of 90Y and 166Ho After Transarterial Radioembolization of Liver Tumors.

OBJECTIVE. The aim of this study was to evaluate the amount of free radioactivity in renal and intestinal excretions during the first 48 hours after transarterial radioembolization (TARE) procedures on the liver. SUBJECTS AND METHODS. Urinary, intestinal, and biliary excretions of patients who underwent TARE with three different types of microspheres were collected during a postinterventional period of 48 hours (divided into two 24-hour intervals). Radioactivity measurements were performed. The detected amounts of activity were correlated to clinical and procedural characteristics, times of excretion, and microsphere types. RESULTS. Twenty-four patients were evaluated, 10 treated with 90Y-glass, 10 with 90Y-resin, and four with 166Ho-poly-L-lactic acid (PLLA) microspheres. Activity excretion occurred in all cases. The highest total excretion proportions of the injected activities were 0.011% for 90Y-glass, 0.119% for 90Y-resin, and 0.005% for 166Ho-PLLA microspheres. Intestinal excretion was markedly less than renal excretion (p < 0.001). Excretion after TARE with 90Y-resin was statistically significantly higher than with 90Y-glass or 166Ho-PLLA micro-spheres (p = 0.002). For each microsphere type, the excreted activity was independent of the activity of the injected microspheres. CONCLUSION. Renal and intestinal excretion of radioactivity after TARE is low but not negligible. The radiation risk for individuals interacting with patients can be minimized if contact with urine and bile is avoided, particularly during the first 24 hours after the procedure.

Case report of a cystic parathyroidal adenoma with rapid growth induced by cinacalcet.

BACKGROUND: Primary hyperparathyroidism is a rare condition of disease which can seldomly present as giant retrotrhyroideal cysts, complicating the localization of the adenoma to resect. CASE PRESENTATION: A 56-year old female presented with hypercalcaemia of 3.38 mmol/L (2.2-2.65 mmol/L) and a history of breast cancer. A fast growing cystic parathyroidal adenoma was diagnosed by a multimodal approach including comprehensive diagnostic imaging (ultrasonography, scintigraphies, dynamic MRI) and cytopathological investigations after ultrasonography-guided puncture. The patient was cured by surgical extraction of the whole adenoma. In retrospect, the rapid growth was most likely induced by cinacalcet (initially 30 mg/d, later 60 mg/d) therapy which the patient received for few months only. Primary hyperparathyroidism was ascertained because surgical removal of the solitary adenoma cured the patient. Furthermore, there was no relevant renal insufficiency or history of prolonged calcium-level deregulation. CONCLUSIONS: This phenomenon of cystic degeneration of parathyroidal adenoma under therapy with cinacalcet has previously been described in secondary hyperparathyroidism, but not in primary hyperparathyroidism and should be considered in diagnostic approach.

Fusion iENA Scholar Study: Sensor-Navigated I-124-PET/US Fusion Imaging versus Conventional Diagnostics for Retrospective Functional Assessment of Thyroid Nodules by Medical Students.

In conventional thyroid diagnostics, the topographical correlation between thyroid nodules (TN) depicted on ultrasound (US) in axial or sagittal orientation and coronally displayed scintigraphy images can be challenging. Sensor-navigated I-124-PET/US fusion imaging has been introduced as a problem-solving tool for ambiguous cases. The purpose of this study was to investigate the results of multiple unexperienced medical students (MS) versus multiple nuclear medicine physicians (MD) regarding the overvalue of I-124-PET/US in comparison to conventional diagnostics (CD) for the functional assessment of TN. METHODS: Out of clinical routine, cases with ambiguous findings on CD were selected for I-124-PET/US fusion imaging. Sixty-eight digital patient case files (PCF) of 34 patients (CDonly and CD+PET/US PCF) comprising 66 TN were provided to be retrospectively evaluated by 70 MD and 70 MS, respectively. A total of 2174 ratings (32.9 per TN) were carried out: 555 ratings (8.4 per TN) for CDonly and 532 ratings (8.1 per TN) for CD+PET/US by each MD and MS. RESULTS: Functional assessment revealed 8.5%/11.7% (n.s.) (16.4%/25.8% (p = 0.0002)), 41.8%/28.5% (p < 0.0001) (23.9%/17.9% (p = 0.0193)), 36.0%/30.5% (n.s.) (57.3%/53.9% (n.s.)), and 13.7%/29.4% (p < 0.0001) (2.4%/2.4% (n.s.)) hyperfunctioning, indifferent, hypofunctioning, and not rateable TNs for CDonly (CD+PET/US) and MD/MS, respectively. The respective rating confidence was indicated as absolute certain, quite certain, equivocal, uncertain, and not rateable in 11.7/3.4% (p < 0.0001) (44.9%/38.9% (p = 0.0541), 51.9%/26.7% (p < 0.0001) (46.2%/41.5% (n.s.)), 21.6%/29.0% (p = 0.0051) (6.2%/14.8% (p < 0.0001)), 1.1%/11.5% (p < 0.0001) (0.2%/2.3% (p = 0.0032)), and 13.7%/29.4% (p < 0.0001) (2.4%/2.4% (n.s.)) by MD/MS, respectively. There was a significant difference in the diversity of the observers' functional assessment of TN (MD 0.84 vs. MS 1.02, p = 0.0006) and the respective confidence in functional assessment (MD 0.93 vs. MS 1.16, p < 0.0001) between MD and MS on CDonly, whereas CD+PET/US revealed weaker differences for both groups (MD 0.48 vs. MS 0.47, p = 0.57; and MD 0.66 vs. MS 0.83, p = 0.0437). With the additional application of I-124-PET/US, the rating diversity of both MD and MS markedly tends towards more consistency (p < 0.0001 in each case). CONCLUSION: The additional application of sensor-navigated I-124-PET/US fusion imaging significantly influenced the functional assessment of TN positively, especially for unexperienced observers.

Ex Vivo Evaluation of Residual Activity and Infusion Dynamics in a Commercially Available Yttrium-90 Resin Microsphere Administration System.

PURPOSE: To evaluate the infusion dynamics and residual yttrium-90 activity during and after resin microsphere radioembolization with different injection techniques and initial activities. To assess the distribution of residual activity in the administration systems to allow optimization of the procedure and the equipment. MATERIALS AND METHODS: In a setup similar to that in standard clinical practice, radioembolization procedures were performed ex vivo. The influence of different injection techniques was assessed by comparing pulsatile and continuous injections. The influence of the absolute amount of activity to the residual activity was assessed by comparing pulsatile 0.5-GBq- with 1.0-GBq-procedures. Continuous dose rate measurements were performed. Activity distribution was determined by positron-emission tomography (PET)/CT. RESULTS: Fifteen procedures were performed: 5 pulsatile 0.5-GBq-, 5 continuous 0.5-GBq-, and 5 pulsatile 1.0-GBq-procedures. Mean residual activity was 4.0% ± 1.7% (range 1.2%-6.6%), without statistically significant differences between injection techniques (P = .841) or between prescribed activities (P = .222). Dose-rate measurements revealed an exponential decrease of the activities in the vials with high variability. Activity fell rapidly to 32% ± 7.9% (range 23%-55%) after injection of 4 of 20 mL 5% dextrose solution. Residual activity accumulations were identified at the 3-way stopcock (100% of procedures), in the C-line (80%), at the microcatheter connector (20%), and in the A-line (6.7%), but not in the vials. CONCLUSIONS: Residual activity in a commercial administration system for resin microsphere radioembolization is variable and does not systematically depend on initial yttrium-90 activity or on injection technique. Predilection sites for residual activity were identified, which should receive special attention when performing resin transarterial radioembolization procedures, and for further administration system developments.

Standard Needle Magnetization for Ultrasound Needle Guidance: First Clinical Experiences in Fine-Needle Aspiration Cytology of Thyroid Nodules.

Fine-needle aspiration cytology using a novel ultrasound needle guidance system on the basis of standard needle magnetization was consecutively performed in 30 (15 in-plane and 15 out-of-plane) suspicious thyroid nodules. Nondedicated, commercially available needles were used. The technical effectiveness and safety of the system were satisfying; system failures were observed in 2 cases. The needle tip could be (at least occasionally) visualized inside the thyroid nodule in 96%, and the subjective procedure ratings were excellent in 57%. The out-of-plane technique was significantly superior in both respects (P = .021 and .027, respectively). Standard needle magnetization ultrasound needle guidance was easy to apply and cost-effective and has the potential to improve fine-needle aspiration cytology performance.

Static and Functional MR Urography to Assess Congenital Anomalies of the Kidney and Urinary Tract in Infants and Children: Comparison With MAG3 Renal Scintigraphy and Sonography.

OBJECTIVE: The purpose of this study is to compare functional MR urography (MRU) with the results of ultrasound and radionuclide 99mTc-mercaptoacetyltriglycine (MAG3) scintigraphy in evaluating morphologic findings, split renal function, and urinary tract obstruction in pediatric patients. MATERIALS AND METHODS: Pediatric 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. RESULTS: 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%. CONCLUSION: 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.

Dependence of Renal Uptake on Kidney Function in [68Ga]Ga-PSMA-11 PET/CT Imaging.

(1) Background: PSMA ligand PET/CT is increasingly important for diagnostics of prostate cancer and other tumor diseases. In particular, the radiopharmaceutical [68Ga]Ga-PSMA-11 is widely used. Besides its tumor-specific binding, the uptake within the kidneys is dominant and seems to visualize the renal cortex specifically. Kidney diseases may alter the uptake of radiopharmaceuticals. Therefore, the correlation between renal uptake in PET/CT imaging and renal function should be investigated. (2) Methods: A group of 103 male patients were retrospectively evaluated for eGFR according to the CKD-EPI equation, tracer uptake intensity (SUVmax, SUVpeak, SUVmean), the molecular volume of the renal cortex, morphological kidney size, and total renal uptake. Manual and three different computer-assisted contouring methods (thresholds at 50% of SUVmax, 30% of SUVmax, and absolute SUV of 20) were used for measurements. Correlations between parameters were calculated using linear regression models. (3) Results: Renal SUVmax, SUVpeak, and SUVmean do not correlate with eGFR for manual or computer-assisted measurements. In contrast, molecular cortex volume shows a moderate correlation with eGFR (R2 = 0.231, p < 0.001), superior to morphological kidney size. A contouring threshold of 30% of SUVmax outperformed the other settings for renal cortex volume and total renal uptake. (4) Conclusions: Renal uptake of [68Ga]Ga-PSMA-11 cannot predict eGFR, but the functional renal cortex can be quantified by PET/CT imaging.

Transarterial Radioembolization (TARE) in Patients with Hepatocellular Carcinoma: A Comparison of Palliative with Bridging-to-Transplant Concepts.

We investigated transarterial radioembolization (TARE) as a palliative measure and bridging-to-transplant therapy in hepatocellular carcinoma (HCC) patients. A total of 167 patients (50 bridging, 117 palliative) with 245 TARE procedures were assessed. Fourteen patients underwent subsequent liver transplantation (LT). Patients undergoing LT exhibited significantly prolonged progression-free survival (PFS) compared to those with bridging-without-transplant (p = 0.033). No significant differences were observed between patients with bridging-without-transplant and palliative cases (p = 0.116). Median overall survival (OS) post-TARE was 16.6 months, with estimated OS rates at 6/12 months of 82.0%/60.5%, respectively. Patients who underwent LT demonstrated statistically significantly longer OS compared to those with bridging-without-transplant (p = 0.001). No marked outcome distinctions were found between bridging-without-transplant and palliative groups. The findings underscored the superiority of LT over alternative treatments. TARE served as an important component in non-LT scenarios, allowing for subsequent therapeutic options. The study reflected the highly variable and complex situations of patients with HCC, emphasizing the need for further investigations to define an optimal multimodal approach.

Correct and Incorrect Recommendations for or against Fine Needle Biopsies of Hypofunctioning Thyroid Nodules: Performance of Different Ultrasound-based Risk Stratification Systems.

PURPOSE: To evaluate the recommendations for or against fine needle biopsy (FNB) of hypofunctioning thyroid nodules (TNs) using of five different Ultrasound (US) -based risk stratification systems (RSSs). METHODS: German multicenter study with 563 TNs (≥ 10 mm) in 534 patients who underwent thyroid US and surgery. All TNs were evaluated with ACR TI-RADS, EU-TIRADS, ATA, K-TIRADS 2016 and modified K-TIRADS 2021. A correct recommendation was defined as: malignant TN with recommendation for FNB (appropriate) or benign TN without recommendation for FNB (avoided). An incorrect recommendation was defined as: malignant TN without recommendation for FNB (missed) or benign TN with recommendation for FNB (unnecessary). RESULTS: ACR TI-RADS demonstrated the highest rate of correct (42.3 %) and lowest rate of incorrect recommendations (57.7 %). The other RRSs showed similar results for correct (26.5 %-35.7 %) and incorrect (64.3 %-73.5 %) recommendations. ACR TI-RADS demonstrated the lowest rate of unnecessary (73.4 %) and the highest rate of appropriate (26.6 %) FNB recommendation. For other RSSs, the rates of unnecessary and appropriate FNB were between 75.2 %-77.1 % and 22.9 %-24.8 %. The lowest rate of missed FNB (14.7 %) and the highest rate of avoided FNB (85.3 %) was found for ACR TI-RADS. For the other RSSs, the rates of missed and avoided FNB were between 17.8 %-26.9 % and 73.1 %-82.2 %. When the size cutoff was disregarded, an increase of correct recommendations and a decrease of incorrect recommendations was observed for all RSSs. CONCLUSION: The RSSs vary in their ability to correctly recommend for or against FNB. An understanding of the impact of nodule size cutoffs seems necessary for the future of TIRADS.