Imaging of Chemokine Receptor 4 Expression in Neuroendocrine Tumors - a Triple Tracer Comparative Approach.

C-X-C motif chemokine receptor 4 (CXCR4) and somatostatin receptors (SSTR) are overexpressed in gastro-entero-pancreatic neuroendocrine tumors (GEP-NET). In this study, we aimed to elucidate the feasibility of non-invasive CXCR4 positron emission tomography/computed tomography (PET/CT) imaging in GEP-NET patients using [68Ga]Pentixafor in comparison to 68Ga-DOTA-D-Phe-Tyr3-octreotide ([68Ga]DOTATOC) and 18F-fluorodeoxyglucose ([18F]FDG). Twelve patients with histologically proven GEP-NET (3xG1, 4xG2, 5xG3) underwent [68Ga]DOTATOC, [18F]FDG, and [68Ga]Pentixafor PET/CT for staging and planning of the therapeutic management. Scans were analyzed on a patient as well as on a lesion basis and compared to immunohistochemical staining patterns of CXCR4 and somatostatin receptors SSTR2a and SSTR5. [68Ga]Pentixafor visualized tumor lesions in 6/12 subjects, whereas [18F]FDG revealed sites of disease in 10/12 and [68Ga]DOTATOC in 11/12 patients, respectively. Regarding sensitivity, SSTR-directed PET was the superior imaging modality in all G1 and G2 NET. CXCR4-directed PET was negative in all G1 NET. In contrast, 50% of G2 and 80% of G3 patients exhibited [68Ga]Pentixafor-positive tumor lesions. Whereas CXCR4 seems to play only a limited role in detecting well-differentiated NET, increasing receptor expression could be non-invasively observed with increasing tumor grade. Thus, [68Ga]Pentixafor PET/CT might serve as non-invasive read-out for evaluating the possibility of CXCR4-directed endoradiotherapy in advanced dedifferentiated SSTR-negative tumors.

Identification of risk factors for catheter-related thrombosis in patients with totally implantable venous access ports in the forearm.

PURPOSE: To identify risk factors for the development of catheter-related thrombosis (CRT) in patients with totally implantable venous access ports (TIVAP) in the forearm, and to analyze the effect of prophylaxis and treatment. METHODS: We retrospectively identified 200 patients (94 men, 106 women, mean age 57.7 +/-14 y) with TIVAP implantation in the forearm between 3/2010 and 11/2010. Type, number of punctures and sonographically defined diameter of the accessed vein were analyzed. Chemotherapy administered prior to the implantation procedure and history of thrombo-embolic events were assessed. Thrombo-embolic prophylaxis (TEP) following port implantation and treatment as well as course of CRT were analyzed. RESULTS: Twenty-one patients (10.5%) were diagnosed with CRT. Accessed vessels and mean diameter were basilic (n=150, 3.7 mm), brachial (n=39, 3.5 mm) and cephalic (n=11, 3.5 mm) vein. Neither type nor vessel diameter had effect on CRT development (P>.05). Implantation in the left forearm resulted in a significantly higher rate of CRT (P=.04). Ninety-five patients (47.5%) received chemotherapy and 30 patients (15.0%) had a history of thrombosis prior to implantation; both had no effect on development of CRT. Low molecular weight heparin (LMWH) was prescribed in 94/200 patients (47.0%) and had no effect on development of CRT (P>.05). Therapeutic anticoagulation with LMWH resulted in clinical improvement in 12/21 patients (57.4%). CONCLUSIONS: TIVAPs of the forearm may be associated with a certain rate of early and late CRT. The simplest vein to puncture should be selected for vascular access. Thrombo-embolic prophylaxis appears to be rather ineffective for prevention of CRT.