We aimed to evaluate 68 Ga-DOTATATE PET/CT for the early prediction of time to progression and clinical outcome after a first cycle of peptide receptor radionuclide treatment (PRRT) in a cohort of patients with well-differentiated neuroendocrine tumors. Methods: Thirty-three consecutive patients (22 men and 11 women; mean age 6 SD, 57.8 6 12.1 y) were investigated at baseline and again 3 mo after initiation of the first cycle of PRRT. 68 Ga-DOTATATE receptor expression was assessed using 2 measures of standardized uptake value (SUV): maximum SUV (SUV max ) and tumor-to-spleen SUV ratio (SUV T/S ). Percentage change in SUV scores after PRRT relative to baseline (DSUV) was calculated. After completing 1-3 cycles of PRRT, patients entered the follow-up study, for estimation of time to progression. According to the Response Evaluation Criteria in Solid Tumors, progression was defined on the basis of contrast-enhanced CT. Clinical symptoms, as well as the tumor markers chromogranin A and neuron-specific enolase, were also recorded during regular follow-up visits. Results: The 23 of 31 patients with decreased SUV T/S after the first PRRT cycle had longer progression-free survival than did the 8 of 31 patients with stable or increased scores (median survival not reached vs. 6 mo, P 5 0.002). For the 18 of 33 patients showing a reduction in SUV max , there was no significant difference in progression-free survival (median survival not reached vs. 14 mo, P 5 0.22). Multivariate regression analysis identified SUV T/S as the only independent predictor for tumor progression during follow-up. In the 17 of 33 patients with clinical symptoms before PRRT, DSUV T/S correlated with clinical improvement (r 5 0.52, P , 0.05), whereas DSUV max did not (r 5 0.42, P 5 0.10). Changes in the tumor markers (chromogranin A and neuronspecific enolase) did not predict DSUV scores, clinical improvement, or time to progression. Conclusion: Decreased 68 Ga-DOTATATE uptake in tumors after the first cycle of PRRT predicted time to progression and correlated with an improvement in clinical symptoms among patients with welldifferentiated neuroendocrine tumors; DSUV T/S was superior to DSUV max for prediction of outcome.

90 Y radioembolization (selective internal radiation therapy [SIRT]) has emerged as a valuable therapeutic option in unresectable, chemotherapy-refractory hepatic metastases from breast cancer. The objective of the present study was to evaluate 18 F-FDG PET/ CT for predicting survival in these patients. Methods: Fifty-eight consecutive patients with hepatic metastases from breast cancer were treated with SIRT. Before therapy, all patients underwent MRI of the liver. 18 F-FDG PET/CT was performed at baseline and 3 mo after SIRT to calculate percentage changes in maximum 18 F-FDG standardized uptake value (SUV max ) relative to baseline. A decrease of more than 30% in the follow-up scan, compared with the baseline examination, indicated therapy response. Treatment response at 3 mo was also assessed in 43 patients using contrastenhanced MRI and CT on the basis of the Response Evaluation Criteria in Solid Tumors. All patients were followed to complete survival data. Results: Overall median survival after SIRT was 47 wk. Response as assessed with SUV max correlated significantly with survival after radioembolization, with responders having significantly longer survival (65 wk) than nonresponders (43 wk; P , 0.05). In multivariate analysis the change in SUV max was identified as the only independent predictor of survival (hazard ratio, 0.23; P , 0.005). Furthermore, a high pretherapeutic SUV max (.20) was associated with a significantly shorter median survival than was an SUV max of 20 or less (21 vs. 52 wk; P , 0.005). The presence of extrahepatic metastases (mean survival in both groups, 47 wk; P 5 0.92), hormone receptor status (estrogen, P 5 0.53; progesterone, P 5 0.79; Her-2/neu, P 5 0.49), and MRI/CT response (P 5 0.91) did not predict survival. Conclusion: The change in SUV max as assessed by 18 F-FDG PET/CT before and 3 mo after SIRT was identified as the only independent predictor of survival in patients with hepatic metastases of breast cancer. Breastcanceri s the most common malignancy affecting women in developed countries. Despite advances in adjuvant treatment, about 20% of patients with initially local disease will still develop metastases (1), frequently involving the liver. In most patients, curative surgical resection of liver metastases is not an option because of the presence of extrahepatic disease or multisegmental involvement of the liver. Other local therapies, such as radiofrequency ablation, are feasible in only a limited number of patients exhibiting only a few, small hepatic metastases. Despite significant advances in chemotherapeutic options in metastatic breast cancer, the presence of liver metastases limits survival in up to 60% of patients. Median survival in women exhibiting liver metastases of breast cancer has been estimated at about 18 mo (2).More recently, radioembolization using 90 Y-microspheres (selective internal radiation therapy [SIRT]) has emerged as a palliative treatment for hepatic metastases of various tumors (3-6). In hepatic metastases of breast cancer (7-9), reported...

In patients with suspected but yet not localized neuroendocrine tumors (NETs), early diagnosis or reliable exclusion is crucial for optimal individual prognosis and therapy. Despite recourse to several imaging modalities, the definite diagnosis of NET can be challenging. Therefore, we tested 68 Ga-DOTATATE PET/CT as a tool for improved diagnosis in a cohort of patients with suspected, nonlocalized NET. Methods: 68 Ga-DOTATATE PET/CT recordings were obtained in 104 consecutive patients meeting at least one of the following criteria: clinical suspicion of NET (n 5 70), elevated blood levels of tumor markers (n 5 49), and image-based suspicion of NET (n 5 53). The presence of NET was validated by histopathology (n 5 49) or clinical follow-up of 107 6 59 wk (n 5 55). Results: In 36 of 104 patients (35%), NET was histologically verified, most frequently located in the small bowel (10/36), pancreas (8/36), lung (5/36), and stomach (2/36). Twelve patients had tumors of nonneuroendocrine origin, and 7 patients had benign tumors. 68 Ga-DOTATATE PET/CT identified NET in 29 of the 36 cases and excluded the presence of a NET in 61 of the 68 non-NET patients, indicating a sensitivity of 81% and specificity of 90%. The PET/CT gave a false-positive result in 7 patients and a false-negative in another 7 patients, indicating positive and negative predictive values of 81% and 90%, respectively, and an accuracy of 87%. Chromogranin A levels were significantly higher in both PET-positive patients (1,841 vs. 342 ng/mL; P , 0.05) and patients with verified NET (2,214 vs. 524 ng/mL; P , 0.05). Conclusion: In patients with suspected NETs due to clinical symptoms, elevated levels of tumor markers, or indeterminate tumors suggestive of NET, 68 Ga-DOTATATE PET/CT is highly accurate, thus supporting its use in clinical routine diagnostics.

(68)Ga-DOTATATE PET/CT is accurate in detection of recurrent NET. Blinded PET/CT review markedly decreased sensitivity, underlining importance of considering clinical parameters in NET recurrence. Present results must be further validated to substantiate use of (68)Ga-DOTATATE PET/CT in routine follow-up after curative resection of NET.

We evaluated the utility of the selective dopamine D 2/3 receptor ligand 18 F-desmethoxyfallypride ( 18 F-DMFP) for the differential diagnosis of patients with idiopathic parkinsonian syndrome (IPS) and nonidiopathic parkinsonian syndrome (non-IPS). On the basis of the superior sensitivity of PET, we hypothesized that 18 F-DMFP should have properties for the differential diagnosis of these syndromes superior to what has been reported for the more conventional SPECT procedures. Methods: A series of 81 patients with parkinsonism (26 women, 55 men; mean age 6 SD, 68 6 11 y) were included in this retrospective analysis. A 30-min 18 F-DMFP PET recording was acquired starting 1 h after injection of the tracer (180-200 MBq, intravenously). The specific binding (SB) in divisions of the striatum was calculated relative to the occipital cortex using an observer-independent semiautomatic volume-of-interest-based technique. The optimal SB threshold was defined by means of receiver-operatingcharacteristic analysis, which was also used for the evaluation of the diagnostic performance of SB, ratios between striatal subregions, and absolute asymmetries in SB. Results: Significant differences (P , 0.001) were found in striatal SB between IPS and non-IPS, most notably in the posterior putamen, for which the diagnostic power for discrimination of IPS and non-IPS was the highest (sensitivity, 87%; specificity, 96%; and accuracy, 91%). A further gain of diagnostic power (sensitivity, 92%; specificity, 96%; and accuracy, 94%) was obtained through discriminant analysis combining 3 parameters: SB of the posterior putamen, the posterior-to-anterior putamen ratio, and the posterior putamen-to-caudate ratio. Conclusion: 18 F-DMFP PET is useful for the differential diagnosis of IPS and non-IPS in patients with parkinsonism. The findings are consistent with relative sparing of D 2/3 receptors in the dopamine-denervated putamen of IPS patients, in contrast to a more substantial loss of striatal dopamine receptors in non-IPS patients. The PET procedure for this differential diagnosis was superior to the reported experience with 123 I-iodobenzamide SPECT.