Aim: Retrospective evaluation of the impact of integrated positron emission tomography/computed tomography (PET/CT) using ⁶⁸Ga-DOTA(0)-Phe(1)-Tyr(3)-octreotide (⁶⁸Ga-DOTATOC) on the therapeutic management of patients with neuroendocrine tumors (NET). Methods: The ⁶⁸Ga-DOTATOC-PET/CT data of 66 patients (31 male, 35 female; age: 29–79, mean age: 56 years) with known or suspected NET were included. Imaging data (PET and triple-phase contrast-enhanced CT) were evaluated in consensus by two readers for the visualization of NET manifestations. Combined PET/CT, clinical and imaging follow-up as well as histopathology (if available) served as the reference standard. In order to assess the impact of the respective submodalities on the therapeutic strategy chosen, the results were compared to the treatment decision made by the interdisciplinary NET tumor board of our institution. Results: Two of the initial 66 patients included did not suffer from NET according to further immunohistopathological examination. In 50 of the remaining 64 (78%) NET patients, a total of 181 NET manifestations were detected by PET/CT. 59/181 (32.6%) were detected by one submodality only (CT 17.1%, PET 15.5%, p for comparison of both = 0.459). Combined PET/CT reading had an impact on the therapeutic management in 24 of 64 (38%) NET patients: primary resection (n = 5), curative lymph node resection (n = 1), initiation/switch of chemotherapy (CTx) due to progressive disease (n = 10), no surgery due to systemic disease (n = 2), radiopeptide receptor therapy instead of CTx (n = 1), additional bisphosphonate therapy (n = 4), and hepatic brachytherapy (n = 1). In 12 of 24 (50%) of these patients, relevant findings were detected by a single submodality only: CT (n = 5), PET (n = 7); p for comparison = 0.774). Conclusion:⁶⁸Ga-DOTATOC-PET/CT influences therapeutic management in about one third of patients examined. CT and PET are comparably sensitive, deliver complementary information and equally contribute to therapeutic decision-making. Thus, despite the merits of the PET modality, the CT component must not be neglected and an optimized multiphase CT protocol is recommended.

The diagnostic value of neuroendocrine tumor (NET) imaging using PET with integrated CT is dependent on both components. This retrospective study assessed the value of the single CT phases of a triple-phase (early arterial, portal-venous inflow, and venous) CT protocol in comparison to 68 Ga-DOTATOC PET in a masked reading. Methods: 68 Ga-DOTATOC PET/CT examinations from 51 patients with known or suspected NET were included. Two readers assessed the data of PET and each of the 3 CT phases for NET lesions independently (using a 3-point score: 1 5 benign, 2 5 indeterminate, and 3 5 malignant) and by consensus (using binary benign/malignant interpretation only). Only lesions within the field of the abdominal scan were evaluated. Clinical and imaging follow-up, histopathology (if available), and the decision of an interdisciplinary truth-panel served as a standard of reference. In addition to the calculation of standard statistical parameters (including general linear mixed models), interobserver reliability was estimated (Cohen's k). Results: Of 510 abdominal lesions observed, 354 were classified as malignant. Sensitivity was 77.1% for combined triplephase CT, 53.4% for arterial CT, 66.1% for portal-venous CT, 66.9% for venous CT, and 72.8% for PET. The respective specificities were 85.3%, 92.9%, 92.3%, 89.7%, and 97.4%, and the respective accuracies were 79.6%, 65.5%, 74.1%, 73.9%, and 80.4%. Although arterial CT was found to be inferior to PET, portal-venous CT, and venous CT (P , 0.001), the differences between the other scans were not significant. Detection was exclusively by PET for 16.1% of lesions, by triple-phase CT for 20.3%, by arterial CT for 0.5%, by portal-venous CT for 3.9%, and by venous CT for 3.9%. Regarding interobserver reliability, the k-value was 0.768 for PET, 0.391 for triple-phase CT, 0.577 for arterial CT, 0.583 for portal-venous CT, and 0.482 for venous CT. Conclusion: No CT phase can be omitted in NET imaging, and the triple-phase protocol continues to be strongly recommended also for PET/CT.

The iPET interpretation assured low interobserver variability. High sensitivity for identification of pHL patients suffering relapse is achieved if [18F]-fluorodeoxyglucose uptake above the MBPS value is rated as a PET-positive finding.

Aim: In combinedpositron emission tomography/computed tomography (PET/CT) of neuroendocrine neoplasms using ⁶⁸Ga-DOTA(0)-Phe(1)-Tyr(3)-octreotide (⁶⁸Ga-DOTATOC), partial volume effects (PVEs) may occur in smaller lesions. This study determined the lesional cutoff size for the occurrence of PVEs in a clinical setting. Methods: Retrospective assessment of 51 PET/CT examinations (16-slice PET/CT device) for malignant PET foci was carried out. In all foci, the maximal standardized uptake value (SUVmax) and maximal lesion diameter on axial CT was documented. Determined SUVmax and lesional sizes were correlated via LOESS regression. In the resulting curve, the cutoff point for SUVmax size dependency was determined visually and mathematically using 2 approximating straight lines. Results: In 45 patients, 313 of 413 PET foci found were malignant, measurable on CT and had a roughly spherical geometry (SUVmax: 2.5-103.3, mean ± SD 20.5 ± 15.18; CT diameter: 5-103 mm, mean ± SD 21.8 ± 13.1 mm). The cutoff lesional size for the occurrence of PVEs was 20.4 mm by the mathematical approach and 25 mm by visual assessment. Conclusion: In ⁶⁸Ga-DOTATOC imaging, the clinical lesional size threshold is far larger than expected from systemic resolution only. Thus, tracer uptake quantification is only acceptable in sufficiently large lesions.

Position-dependent renal perfusion should be considered in patients with large blood pressure fluctuations and extreme dipping. If morphological imaging shows no abnormalities, functional imaging provides additional information. Further investigation is needed, foremost if nephropexy could improve blood pressure control in some of these patients.

CT-guided sympathetic denervation proved to be safe and applicable under various anatomical conditions with more renal arteries and such of small diameter.

Most cervical artery dissections occur spontaneously, but traumatic mechanisms can occasionally be identified. Traumatic internal carotid artery dissection has been attributed with several sports, but there are no reports of its occurrence in thriathlon. We report the case of a 63-year-old semi-professional triathlete, who noticed right-sided neck pain and parietooccipital headache after a triathlon competition. Neurological examination revealed an incomplete right Horner's syndrome. MRI and MR-angiography demonstrated a right-sided internal carotid artery dissection with segmental loss of flow-signal and a mural haematoma in the vessel wall. In this case two pathophysiological mechanisms may be considered. Our patient reported receiving several blows to the neck in a congested 50-metre pool during the triathlon swimming stage. Furthermore, the hyperextended position of the neck during the subsequent cycling stage may have contributed, to a large extent, to the arterial dissection. The risk factors, presenting symptoms, diagnosis of internal carotid artery dissection are reviewed.

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