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The expression status of human epidermal growth factor receptor 2 (HER2) in cancer predicts response to HER2-targeted therapy. Therefore, its accurate determination is of utmost importance. In recent years, there has been an increase in research on noninvasive techniques for molecular imaging, as this method offers the advantages of a more accurate determination of HER2 status without the need for multiple biopsies. The technetium-labeled single-domain antibody RAD201, previously known as 99m Tc-NM-02, has been shown to be safe for use in breast cancer imaging with reasonable radiation doses, favorable biodistribution, and imaging characteristics., Methods: A total of six HER2-positive, heavily pretreated patients with different cancer types aged between 42 and 69 years (5 women and 1 man; the median age of 55.5) have been examined. In six of seven scans, the patients were administered 500 ml of Gelofusine® solution (40 mg/ml) for radiation protection before the tracer injection (434 ± 42 MBq). Planar scans were acquired with the patient supine at 10 min, 60 min, 160 min, 20 h, and 24 h after injection. A CT scan was acquired at 95 min, followed by local tomographic SPECT imaging., Results: One patient was scanned twice with RAD201, 3 months apart, resulting in a total of seven scans for six patients. Here, we show that the use of RAD201 in our patient group shows the same favorable biodistribution as in a previous study with RAD201 (NCT04040686) and that the radiation dose to the critical organ kidney can be reduced by the application of the plasma expander Gelofusine® by almost 50%., Conclusion: RAD201 appears safe for use in humans and is a promising noninvasive tool for discriminating HER2 status in metastatic (breast) cancer, regardless of ongoing HER2-targeted antibody treatment., (© 2022. The Author(s).)

Purpose: The aim of the present paper is to review the role of HER2 antibodies, affibodies and nanobodies as vehicles for imaging and therapy approaches in breast cancer, including a detailed look at recent clinical data from antibody drug conjugates and nanobodies as well as affibodies that are currently under development., Results: Clinical and preclinical studies have shown that the use of monoclonal antibodies in molecular imaging is impaired by slow blood clearance, associated with slow and low tumor uptake and with limited tumor penetration potential. Antibody fragments, such as nanobodies, on the other hand, can be radiolabelled with short-lived radioisotopes and provide high-contrast images within a few hours after injection, allowing early diagnosis and reduced radiation exposure of patients. Even in therapy, the small radioactively labeled nanobodies prove to be superior to radioactively labeled monoclonal antibodies due to their higher specificity and their ability to penetrate the tumor., Conclusion: While monoclonal antibodies are well established drug delivery vehicles, the current literature on molecular imaging supports the notion that antibody fragments, such as affibodies or nanobodies, might be superior in this approach.

Purpose: Increased articular 99m Tc MDP uptake on blood pool imaging (BPI) of patients with rheumatologic conditions is indicative of active inflammatory changes, and has been suggested as a strong predictor of response to radiosynoviorthesis (RSO). In this study, we aimed to assess the value of pretreatment BPI positivity (i.e. scintigraphic-apparent hyperemia) for successful RSO in hemophilic arthropathy., Methods: Thirty-four male patients with painful hemophilic arthropathy underwent RSO after failure of conservative treatment. Treated joints comprised the knee in eight, elbow in five, and ankle in 21 patients. Pretreatment triple-phase bone scintigraphy showed hyperemic joints (pathologic BPI) in 17 patients, whereas 17 patients had no increased tracer uptake on BPI. Response to RSO was evaluated 6 months post-treatment by measuring changes in intensity of arthralgia according to the visual analog scale (VAS), bleeding frequency, and range of motion. The association between hyperemia (pathologic BPI) and treatment outcome was examined using nonparametric tests for independent samples., Results: Clinically evident pain relief occurred in 26 patients (76.5 %), and the mean VAS decreased from 7.7 ± 1.1 to 4.6 ± 2.7 (p < 0.001). Joint bleeding frequency (hemarthrosis) decreased from 4.5 ± 0.6 to 2.1 ± 0.4 during the first 6 months after RSO (p < 0.001). For both parameters (pain relief and bleeding frequency), patients experienced a similar benefit from RSO regardless of pretreatment BPI: arthralgia (p = 0.312) and frequency of hemarthrosis (p = 0.396). No significant improvement was observed for range of motion, but it was significantly more restricted in hyperemic joints both before (p = 0.036) and after treatment (p = 0.022)., Conclusions: Hemophilic arthropathy can be effectively treated with RSO regardless of pre-therapeutic BPI. Patients in whom articular hyperemia is not detectable by scintigraphy may have similar (outstanding) outcomes, and thus should not be excluded from treatment.

Aim: Distant metastasis has a negative impact on survival in differentiated thyroid carcinoma (DTC). The timing of this manifestation, however, is of unknown prognostic relevance. The aim of this retrospective study was to investigate the potential significance of discriminating synchronous versus metachronous distant metastases (SDM vs. MDM) for the outcome of patients with DTC., Methods: We retrospectively analyzed a consecutive cohort of n = 89 patients with distant metastases of DTC (43 with follicular, 46 with papillary DTC histology; mean age 52.6 ± 17.7 years) undergoing radioiodine treatment at our institution. All patients were treated with the same protocol consisting of ablative radioiodine therapy (RIT, 3.7 GBq) and one post-ablation treatment after 3 months (3.7-11.1 GBq). Further cycles of RIT were administered for recurrent, progressive or newly developed metastatic disease. We distinguished 2 types of distant metastases according to the time of manifestation: SDM (within ≤12 months after DTC diagnosis) and MDM (occurring >12 months after diagnosis). Tumor-related survival was analyzed using the Kaplan-Meier method. Uni- and multivariate analyses including the Cox proportional hazards model were performed with a significance level of p < 0.05., Results: The mean follow-up period was 13.8 ± 1.2 years. SDM were present in 49 (55.1 %), MDM in 40 (44.9 %) patients. MDM were associated with shorter tumor-related survival (p = 0.002). 5-year and 10-year survival rates were 68.5 % and 34.8 % for MDM, and 84.3 % and 66.9 % for SDM, respectively. Within both age subgroups of <45 and ≥45 years, SDM were also linked with longer survival. No effect on tumor-related survival was found for the co-variables sex, lymph node metastases and histologic type., Conclusion: Distinguishing synchronous from metachronous manifestation of distant metastases may add an important prognostic feature to risk stratification in DTC, as proven metachronous appearance is associated with impaired survival.

Purpose: Increasing evidence supports the value of peptide receptor radionuclide therapy (PRRT) in patients with metastatic neuroendocrine tumours (NET), but there are limited data on its specific efficacy in NET of small intestinal (midgut) origin. This study aims to define the benefit of PRRT with (177)Lu-octreotate for this circumscribed entity derived by a uniformly treated patient cohort., Methods: A total of 61 consecutive patients with unresectable, advanced small intestinal NET G1-2 stage IV treated with (177)Lu-octreotate (4 intended cycles at 3-month intervals, mean activity per cycle 7.9 GBq) were analysed. Sufficient tumour uptake on baseline receptor imaging and either documented tumour progression (n = 46) or uncontrolled symptoms (n = 15) were prerequisites for treatment. Response was evaluated according to modified Southwest Oncology Group (SWOG) criteria and additionally with Response Criteria in Solid Tumors (RECIST) 1.1. Assessment of survival was performed using Kaplan-Meier curves and Cox proportional hazards model for uni- and multivariate analyses. Toxicity was assessed according to standardized follow-up laboratory work-up including blood counts, liver and renal function, supplemented with serial (99m)Tc-diethylenetriaminepentaacetic acid (DTPA) clearance measurements., Results: The median follow-up period was 62 months. Reversible haematotoxicity (≥ grade 3) occurred in five patients (8.2%). No significant nephrotoxicity (≥ grade 3) was observed. Treatment response according to modified SWOG criteria consisted of partial response in 8 (13.1%), minor response in 19 (31.1%), stable disease in 29 (47.5%) and progressive disease in 5 (8.2%) patients. The disease control rate was 91.8%. Median progression-free survival (PFS) and overall survival (OS) was 33 [95% confidence interval (CI) 25-41] and 61 months (95% CI NA), respectively. Objective response was associated with longer survival (p = 0.005). Independent predictors of shorter PFS were functionality [hazard ratio (HR) 2.1, 95% CI 1.0-4.5, p = 0.05] and high plasma chromogranin A (CgA) levels > 600 ng/ml (HR 2.9, 95% CI 1.5-5.5, p < 0.001) at baseline., Conclusion: PRRT is well tolerated and very effective in advanced well-differentiated small intestinal (midgut) NET. A high disease control rate and long PFS can be achieved with this modality after failure of standard biotherapy with somatostatin analogues. Tumour functionality and high plasma CgA appear to be independent predictors of unfavourable patient outcome.

Purpose: The aim of this study was to evaluate the predictive value of early metabolic response 4 weeks post-treatment using (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in patients with unresectable hepatic metastases of colorectal cancer (CRC) undergoing radioembolization (RE) with (90)Y-labelled microspheres., Methods: A total of 51 consecutive patients with liver-dominant metastases of CRC were treated with RE and underwent (18)F-FDG PET/CT at baseline and 4 weeks after RE. In each patient, three hepatic metastases with the highest maximum standardized uptake value (SUVmax) were selected as target lesions. Metabolic response was defined as >50 % reduction of tumour to liver ratios. Survival analyses using Kaplan-Meier and multivariate analyses were performed to identify prognostic factors for overall survival (OS). Investigated baseline characteristics included age (>60 years), performance status (Eastern Cooperative Oncology Group >1), bilirubin (>1.0 mg/dl), hepatic tumour burden (>25 %) and presence of extrahepatic disease., Results: The median OS after RE was 7 months [95 % confidence interval (CI) 5-8]; early metabolic responders (n = 33) survived longer than non-responders (p < 0.001) with a median OS of 10 months (95 % CI 3-16) versus 4 months (95 % CI 2-6). Hepatic tumour burden also had significant impact on treatment outcome (p < 0.001) with a median OS of 5 months (95 % CI, 3-7) for patients with >25 % metastatic liver replacement vs 14 months (95 % CI 6-22) for the less advanced patients. Both factors (early metabolic response and low hepatic tumour burden) remained as independent predictors of improved survival on multivariate analysis., Conclusion: These are the first findings to show that molecular response assessment in CRC using (18)F-FDG PET/CT appears feasible as early as 4 weeks post-RE, allowing risk stratification and potentially facilitating early response-adapted treatment strategies.

Purpose: The clinical benefit of peptide receptor radionuclide therapy (PRRT) in patients with pancreatic neuroendocrine tumours (pNET) has not yet been well described and defined in its full extent due to limited data in this tumour subgroup. This study was intended to obtain robust, comparative data on the outcome and toxicity of standardized PRRT with (177)Lu-octreotate in a well-characterized population of patients with advanced pNET of grade 1/2 (G1/2)., Methods: We retrospectively analysed a cohort of 68 pNET patients with inoperable metastatic disease consecutively treated with (177)Lu-octreotate (four intended cycles at 3-monthly intervals; mean activity per cycle 8.0 GBq). Of these 68 patients, 46 (67.6 %) had documented morphological tumour progression during the 12 months before initiation of treatment, and PRRT was the first-line systemic therapy in 35 patients (51.5 %). Response was evaluated according to modified Southwest Oncology Group (SWOG) criteria and additionally with Response Criteria in Solid Tumors (RECIST) 1.1. Survival was analysed using Kaplan-Meier curves and Cox proportional hazards model for univariate and multivariate analyses. Toxicity was assessed by standard follow-up laboratory work-up including blood count, and liver and renal function, supplemented with serial (99m)Tc-DTPA clearance measurements., Results: The median follow-up period was 58 months (range 4 - 112). Reversible haematotoxicity (grade 3 or more) occurred in four patients (5.9 %). No significant nephrotoxicity (grade 3 or more) was observed. Treatment responses (SWOG criteria) consisted of a partial response in 41 patients (60.3 %), a minor response in 8 (11.8 %), stable disease in 9 (13.2 %), and progressive disease in 10 (14.7 %). Median progression-free survival (PFS) and overall survival (OS) were 34 (95 % CI 26 - 42) and 53 months (95 % CI 46 - 60), respectively. A G1 proliferation status was associated with longer PFS (p = 0.04) and OS (p = 0.044) in the multivariate analysis. Variables linked to impaired OS, on the other hand, were a reduced performance status (Karnofsky score ≤ 70 %, p = 0.007), a high hepatic tumour burden (≥ 25 % liver volume, p = 0.017), and an elevated plasma level of neuron-specific enolase (NSE >15 ng/ml, p = 0.035)., Conclusion: The outstanding response rates and survival outcomes suggest that PRRT is highly effective in advanced G1/2 pNET when compared to data of other treatment modalities. Independent predictors of survival are the tumour proliferation index, the patient's performance status, tumour burden and baseline plasma NSE level.

Purpose: Renal radiation during peptide receptor radionuclide therapy (PRRT) may result in glomerular damage, a potential reduction of glomerular filtration rate (GFR) and ultimately lead to renal failure. While reported PRRT nephrotoxicity is limited to data derived from serum creatinine-allowing only approximate estimates of GFR-the aim of this study is to accurately determine PRRT-induced long-term changes of renal function and associated risk factors according to state-of-the-art GFR measurement., Methods: Nephrotoxicity was analysed using (99m)Tc-diethylenetriaminepentaacetic acid (DTPA) clearance data of 74 consecutive patients with gastroenteropancreatic neuroendocrine tumours (GEP NET) undergoing PRRT with (177)Lu-octreotate. The mean follow-up period was 21 months (range 12-50) with a median of five GFR measurements per patient. The change of GFR was analysed by linear curve fit. Potential risk factors including diabetes mellitus, arterial hypertension, previous chemotherapy, renal impairment at baseline and cumulative administered activity were analysed regarding potential impact on renal function loss. In addition, Common Terminology Criteria for Adverse Events (CTCAE) v3.0 were used to compare nephrotoxicity determined by (99m)Tc-DTPA clearance versus serum creatinine., Results: The alteration in GFR differed widely among the patients (mean -2.1 ± 13.1 ml/min/m(2) per year, relative yearly reduction -1.8 ± 18.9%). Fifteen patients (21%) experienced a mild (2-10 ml/min/m(2) per year) and 16 patients (22%) a significant (>10 ml/min/m(2) per year) decline of GFR following PRRT. However, 11 patients (15%) showed an increase of >10 ml/min/m(2) per year. Relevant nephrotoxicity according to CTCAE (grade ≥3) was observed in one patient (1.3%) with arterial hypertension and history of chemotherapy. Nephrotoxicity according to serum creatinine was discordant to that defined by GFR in 15% of the assessments and led to underestimation in 12% of patients. None of the investigated factors including cumulative administered activity contributed to the decline of renal function., Conclusion: Serious nephrotoxicity after PRRT with (177)Lu-octreotate is rare (1.3%). However, slight renal impairment (GFR loss >2 ml/min/m(2) per year) can frequently (43%) be detected by (99m)Tc-DTPA clearance assessments. Cumulative administered activity of (177)Lu-octreotate is not a major determinant of renal impairment in our study.

Purpose: We assessed the outcome and toxicity of salvage therapy (repeat treatment) with (177)Lu-octreotate and high cumulative activities in patients with metastatic gastroenteropancreatic neuroendocrine tumours (GEP-NET)., Methods: We retrospectively analysed a consecutive cohort of 33 patients with metastatic GEP-NET who underwent salvage peptide receptor radionuclide therapy (PRRT) in our institution. All patients had progressive NET prior to salvage treatment and had shown an initial response to PRRT. The mean cumulative activity was 44.3 GBq (30.0-83.7 GBq). Radiographic response was assessed using CT and/or MRI according to modified SWOG criteria. Toxicity was evaluated using laboratory data, including complete blood counts and renal function tests using CTCAE 3.0. Survival analysis was performed with the Kaplan-Meier curve method and a significance level at p < 0.05., Results: Radiographic responses consisted of complete response in 1 patient (3.0%), partial response in 6 patients (18.2%), minor response in 1 patient (3.0%), stable disease in 14 patients (42.4%), and progressive disease in 11 patients (33.3%). Median progression-free survival (PFS) from the start of salvage therapy was 13 months (95% CI 9-18) and patients with a history of a durable PFS after initial PRRT tended to have long-lasting PFS after salvage treatment (p = 0.04). None of the patients developed severe nephrotoxicity (grade 3/4) or a myelodysplastic syndrome during follow-up. Relevant albeit reversible haematotoxicity (grade 3/4) occurred in 7 patients (21.2%). The cumulative administered activity was not associated with an increased incidence of haematotoxicity., Conclusion: PRRT with (177)Lu-octreotate in the re-treatment setting is safe and effective in patients with metastatic GEP-NET.

Purpose: Lobar radioembolization (RE) of the liver can result in reduction in volume of the ipsilateral lobe as well as hypertrophy of the contralateral lobe. Theoretically, hypertrophy of the contralateral liver lobe after RE could increase the chance of a successful liver resection, especially in patients with limited liver function reserve. The aim of this preliminary study was to evaluate the early effects of RE with resin microspheres on the volumes of the liver lobes and spleen., Methods: We retrospectively investigated 24 patients (12 women, 44-78 years old) with different types of cancer and liver-dominant metastatic disease who had undergone RE of the liver with resin microspheres. Changes in the volumes of the liver lobes and spleen were quantified by CT before and about 4 to 8 weeks after treatment., Results: Of the 24 patients, 17 suffered from metastases in both liver lobes (group A) and 7 had metastases only in the right liver lobe (group B). The patients in the group A underwent sequential treatment starting with the right liver lobe. The median administered dose was 1.75 GBq. RE was associated with a median increase in volume of the left liver lobe of 34 % (P < 0.001) and a median decrease in volume of the right liver lobe of 11 % (P = 0.03). The volume of the spleen showed a median increase of 17 % (P = 0.01). Separate analysis of the two groups showed a median increases in volume of the left liver lobe of 30 % (P = 0.001) in group A and 70 % (P = 0.01) in group B. There was no correlation between the injected dose and the volume alteration (r = 0.1-0.3)., Conclusion: RE of the right liver lobe with resin microspheres caused a significant increase in the volume of the left liver lobe. This may allow liver resection in patients with metastases in the right liver lobe and a small left liver lobe.

Purpose: Sentinel lymph node biopsy (SLNB) is considered the most powerful prognostic indicator of survival in patients with cutaneous melanoma of intermediate thickness (1-4 mm). The use of SLNB in patients with melanoma with a tumour thickness >4.0 mm is still controversial. The purpose of the current study was to determine the prognostic value of SLNB in patients with thick cutaneous melanomas (tumour thickness >4.0 mm) in terms of progression-free survival (PFS) and overall survival (OS)., Methods: A retrospective single-centre study was performed at the Department of Dermatology and Allergy, University of Bonn, and the Department of Nuclear Medicine, University of Bonn, based on data collected between September 2000 and January 2010. A total of 142 patients with cutaneous melanoma of thickness >4.00 mm were identified, and 63 of these patients underwent SLNB., Results: Of the 63 patients in whom SLNB was performed, 25 (39.7 %) had a positive SLN. Ulceration was more frequent in SLN-positive patients (44 %) than in SLN-negative patients (18.4 %). The mean follow-up time for the 63 patients was 50.7 months. Positive SLN status predicted a significantly reduced life expectancy in the analyses of PFS and OS. In SLN-positive patients 5-year OS was 76 % and in SLN-negative patients was 84.2 % (p = 0.048). Patients with a combination of ulcerated tumour and positive SLN had the worst prognosis., Conclusion: On the basis of our follow-up data, SLNB has to be recommended in patients with a tumour thickness >4.00 mm after exclusion of lymph node macrometastases or distant metastases. SLN status is the most significant prognostic factor in this group of patients.

Purpose: Sentinel lymph node biopsy (SLNB) is a widely accepted procedure to accurately stage melanomas with a thickness ≥1 mm. The value of SLNB in thin melanomas is still controversial, especially because long-term observations of these patients are rare. The purpose of the current study was to identify the positive sentinel lymph node (SLN) ratio in low-risk patients with cutaneous melanoma (CM) of thickness less than 1 mm and its possible prognostic value, focusing on long-term follow-up data., Methods: In a retrospective single-centre study performed at the Department of Dermatology and Allergy, University of Bonn, 121 patients who had received SLNB were identified out of 621 patients with a diagnosis of CM of <1.00 mm thickness presenting between September 2000 and February 2009 (mean follow-up time, 50.9 months)., Results: Of the 121 patients, 5 (4.1%) had a positive SLN. All positive SLNs were found in patients with a tumour thickness between 0.90 mm and 1.00 mm. There were no significant differences in the presence of positive SLNs according to Clark level and ulceration status (Clark levels II and III and no ulceration vs. Clark levels IV and V or ulceration), regression, gender or age. Disease-free survival was 100% in the SLN-positive patients. On the other hand, five SLN-negative patients (4.1%) developed disease progression. One of these five progressive patients showed recurrence in the former negative SLN basin (16.7% false-negative rate)., Conclusion: A positive SLN in thin melanomas is uncommon with a prevalence of 4.1% in our study population. We could not identify reliable clinicopathological risk factors which could predict results of SLNB in thin melanomas. Based on our results, SLNB may be considered in patients with a melanoma of thickness in the range 0.90-0.99 mm, because all SLN-positive patients belonged to this subgroup.

Purpose Unwanted deposition of 90Y microspheres in organs other than the liver during radioembolization of liver tumours may cause severe side effects such as duodenal ulcer. The aim of this study was to evaluate the significance of posttherapy bremsstrahlung (BS) SPECT/CT images of the liver in comparison to planar and SPECT images in the prediction of radioembolization-induced extrahepatic side effects.Methods A total of 188 radioembolization procedures were performed in 123 patients (50 women, 73 men) over a 2-year period. Planar, whole-body and BS SPECT/CT imaging were performed 24 h after treatment as a part of therapy work-up.Any focally increased extrahepatic accumulation was evaluated as suspicious. Clinical follow-up and gastroduodenoscopy served as reference standards. The studies were reviewed to evaluate whether BS SPECT/CT imaging was of benefit.Results In the light of anatomic data obtained from SPECT/CT, apparent extrahepatic BS in 43% of planar and in 52% of SPECT images proved to be in the liver and hence false positive.The results of planar scintigraphy could not be analysed further since 12 images were not assessable due to high scatter artefacts. On the basis of the gastrointestinal (GI)complications and the results of gastroduodenoscopy, true positive,true-negative, false-positive and false-negative results of BS SPECT and SPECT/CT imaging in the prediction of GI ulcers were determined. The sensitivity, specificity, positive and negative predictive values and the accuracy of SPECT and SPECT/CT in the prediction of GI ulcers were 13%, 88%, 8%,92% and 82%, and 87%, 100%, 100%, 99% and 99%,respectively.Conclusion Despite the low quality of BS images, BSSPECT/CT can be used as a reliable method to confirm the safe distribution of 90Y microspheres and in the prediction of GI side effects.

Purpose: While influx of chemoembolic agents into the hepatic falciform artery (HFA) from the hepatic artery can cause supraumbilical skin rash, epigastric pain and even skin necrosis, the significance of a patent HFA in patients undergoing radioembolization is not completely clear. Furthermore, the presence of tracer in the anterior abdominal wall seen in (99m)Tc-macroaggregated albumin ((99m)Tc-MAA) images, which is generally performed prior to radioembolization, has been described as a sign of a patent HFA. The aim of this retrospective study was to evaluate the incidence and consequences of (99m)Tc-MAA accumulation in the anterior abdominal wall, indicating a patent HFA, in patients undergoing radioembolization of liver tumours., Methods: A total of 224 diagnostic hepatic angiograms combined with (99m)Tc-MAA SPECT/CT were acquired in 192 patients with different types of cancer, of whom 142 were treated with a total of 214 radioembolization procedures. All patients received a whole-body scan, and planar and SPECT/CT scans of the abdomen. Only patients with extrahepatic (99m)Tc-MAA accumulation in the anterior abdominal wall were included in this study. Posttreatment bremsstrahlung SPECT/CT and follow-up results for at least 3 months served as reference standards., Results: Tracer accumulation in the anterior abdominal wall was present in pretreatment (99m)Tc-MAA SPECT/CT images of 18 patients (9.3%). The HFA was found and embolized by radiologists before treatment in one patient. In the remaining patients radioembolization was performed without any modification in the treatment plan despite the previously mentioned extrahepatic accumulation. Only one patient experienced abdominal muscle pain above the navel, which started 24 h after treatment and lasted for 48 h without any skin changes. The remaining patients did not experience any relevant side effects during the follow-up period., Conclusion: Side effects after radioembolization in patients with tracer accumulation in the anterior abdominal wall on (99m)Tc-MAA scans indicating a patent HFA are neither common nor severe. Thus, there is no absolute need for prophylactic embolization of the HFA or modification of the treatment plan if the HFA is not detectable on angiography.

Purpose: An angiographic evaluation combined with (99m)Tc-macroaggregated albumin (Tc-MAA) scanning should precede the treatment of any selected candidates for radioembolization (RE) of the liver. If the tumours in one liver lobe have not been targeted in the test angiogram, it should be repeated. However, in a few cases treatment of one liver lobe or at least some segments is safe and feasible and performing a repeated test angiogram with Tc-MAA (Re-MAA) in a separate session leads to more radiation exposure and could be time consuming. Our aim was to evaluate the feasibility of concurrent RE of a part of the liver and therapy planning for another region by simultaneous injection of the Tc-MAA and (90)Y-microspheres in two different locations in the therapy session. Tc-MAA and bremsstrahlung (BS) single photon emission computed tomography (SPECT)/CT were performed separately in an effort to distinguish between the distributions of these two different radiopharmaceuticals., Methods: RE was combined with a simultaneous second test angiogram of another lobe or segments in the same session in six patients [44-70 years; five women (83%)]. Five patients suffered from colorectal carcinoma (CRC) and one from ovarian cancer. Tc-MAA and BS SPECT/CT were performed for all cases., Results: Post-therapeutic Tc-MAA SPECT/CT showed in all patients only the distribution of Tc-MAA without any detectable BS. Evaluation of (90)Y-microsphere distribution was not always possible in the post-therapeutic BS scan performed 24 h later due to remaining Tc-MAA radiation. However, scans performed at 48 h post-intervention no longer showed any Tc-MAA "contamination"., Conclusion: Combining RE and Re-MAA is feasible in appropriately selected patients.

Purpose: The role of the Ki-67 tumour proliferation index (PI) in predicting the efficacy of peptide receptor radionuclide therapy (PRRT) in gastroenteropancreatic tumours (GEP-NET) remains undetermined. This single-centre analysis focused on the potential therapeutic impact of this immunohistochemical parameter., Methods: A total of 81 consecutive GEP-NET patients treated with (177)Lu-DOTA-octreotate (mean activity of 7.9 GBq per cycle, usually four treatment cycles at standard intervals of 3 months) were retrospectively analysed. Both an evaluable PI and tumour response (modified SWOG criteria) were required for patient inclusion., Results: Response of tumours with a PI of ≤20% (partial response 40%, minor response 15%, stable disease 34%, progressive disease 11%) was comparable in all PI subsets, including those with a PI of 20%. However, G3 tumours (PI > 20%) showed progression in 71% of patients., Conclusion: Response to PRRT is consistent over the PI range of ≤20% (G1 + G2). Contrary to preliminary previous suggestions, a PI of 15% or 20% should not preclude candidates from somatostatin receptor-targeted radiotherapy.

Purpose: Recently published data indicated (18)F-fluorocholine to be feasible for imaging vulnerable atherosclerotic plaques in an animal model., Methods: Five patients undergoing whole-body (18)F-fluoromethylcholine-((18)F-FMCH-) PET/CT for imaging of prostate cancer disease were retrospectively evaluated. Whole-body PET scans were started immediately after i.v. injection of (18)F-FMCH. About 5-15 min after tracer injection, acquisition of scans of the pelvis and abdomen was performed. PET, CT, and PET/CT slices were generated for review and visual analyses of the abdominal aorta and the common iliac arteries were performed. Vascular findings in examined arteries and surrounding structures due to artifacts were excluded from further analysis. The lower threshold of (18)F-FMCH uptake was set above the background activity within the examined vessels. Morphological classification of vessel wall alterations (WA) included structural wall alterations without additional calcification (SWA), structural wall alterations associated with calcifications (SWC), and solely calcified lesions (CL). They were correlated with (18)F-FMCH uptake qualified as present and vice versa., Results: A total of 31 WA were identified. Positive (18)F-FMCH uptake was found in 14 lesions (SWA: n = 5; SWC: n = 9). Sixteen of 17 (18)F-FMCH negative lesions were identified as CL without additional structural vessel wall alteration. One SWA did not show any (18)F-FMCH accumulation. None of the CLs as well as unaltered parts of the vessel wall showed (18)F-FMCH uptake., Conclusions: Our initial data in five patients with a total of 31 vessel wall alterations show promising results indicating for the first time the feasibility of (18)F-FMCH for in vivo imaging of structural WA in humans.

Purpose: The aims of this study were to assess the performance of FDG PET at PET/CT imaging for the detection of pulmonary metastases and to evaluate differences in lesion detectability on attenuation-corrected (AC) and non-attenuation corrected (NAC) PET images., Methods: The institutional PET/CT database was searched for patients with pulmonary metastases of 3-60 mm in diameter. Ninety-two patients with 438 metastases to the lungs were included in the study. The primary tumours were 33 malignant melanomas, 12 carcinomas of unknown primary, 11 colorectal carcinomas, eight differentiated thyroid carcinomas, seven aggressive non-Hodgkin's lymphomas, six head and neck cancers, three breast cancers, two prostate cancers and ten others. Lesion detectability was visually compared between PET and CT and between AC and NAC PET images using a five-point scale., Results: Of the 438 pulmonary metastases, 174 were detected with FDG PET (39.7%), six of them on NAC images only (not significant). Visual scores were higher on NAC images in 41.4% and equal in 54.6% of lesions. The sensitivity of FDG PET increased significantly from 0.405 for metastases of 5-7 mm in diameter to 0.784 for lesions of 8-10 mm and to 0.935 for lesions measuring 11-29 mm in diameter. No metastases smaller than 5 mm in diameter were seen on PET images., Conclusion: FDG PET/CT is useful for the assessment of pulmonary metastases. The frequency of lesion detection is similar for AC and NAC PET images. A reduced sensitivity of FDG PET has to be considered for lesions smaller than 11 mm in diameter.