Monitoring Kidney Function in Neuroendocrine Tumor Patients Treated with (90)Y-DOTATOC: Associations with Risk Factors.

Peptide receptor radionuclide therapy (PRRT) is an established treatment for progressive neuroendocrine tumours with nephrotoxicity as the limiting factor. It is therefore important to monitor kidney function changes after PRRT treatment. We aimed to investigate kidney function by different methods and during a 4-hour and a 24-hour amino acid (AA) infusion protocol. We measured the Glomerular Filtration Rate (GFR) in 28 patients before and 3, 6, 12, and 18 months after (90)YDOTATOC therapy. We used standardized (51)Cr-EDTA plasma clearance (Cr-GFR) and estimated GFR (eGFR) by the simplified 4 variable Modification of Diet in Renal Disease based on serum creatinine values. Further, we determined GFR in 15 patients treated with a 4-hour infusion of AA compared to 13 patients with a 24-hour infusion at 3, 6, 12 and 18 months after therapy. Pre-existing risk factors associated with kidney failure were seen in 82% of the patients. We observed a significant reduction in Cr-GFR up to 12 months after PRRT (mean loss 27 ml/min/1.73 m(2) (32%)). The eGFR continuously overestimated the Cr-GFR with a bias of 8%. There was no significant difference between the two AA protocols, however, the 24-hour AA protocol tended to reduce mean Cr-GFR loss 12 months post therapy. Pre-existing risk factors for kidney failure were highly prevalent in this patient cohort, and kidney function after PRRT treatment is best monitored by (51)Cr-EDTA plasma clearance. Further, the use of a 24-hour AA kidney protection protocol seems to reduce the loss of kidney function in these patients.

Accuracy of 18F-FDG PET-CT in triaging lung cancer patients with suspected brain metastases for MRI.

OBJECTIVE: Brain metastases are common in lung cancer. Whole-body 2-deoxy-2-[fluorine-18]fluoro-D-glucose ([F]FDG) PET/computed tomography (CT) is used for general staging, but MRI is the best modality for characterizing brain abnormalities. We aimed to determine whether PET/CT is suitable for selecting patients for MRI on the suspicion of brain metastases. MATERIALS AND METHODS: F-FDG PET/CT (from the vertex to mid-thigh) was performed in 1108 consecutive patients suspected of lung cancer. The final diagnoses were extracted from medical records as lung cancer, with or without brain metastases, other kinds of cancers, or no cancer. The sensitivity, specificity, and positive predictive value for detecting brain metastases were calculated. Interobserver variation was tested in a subset of 88 PET/CT scans. RESULTS: Of the 1108 referred patients, 596 had lung cancer. Sixty-six had brain metastases. One PET/CT was false positive. Thirty-one scans were true positive among the 43 patients who were diagnosed with brain metastases 1 month before to 3 months after PET/CT (metastasis prevalence, 7.3%). Twelve PET/CT scans were false negative. Sensitivity, specificity, and positive predictive values were 72, 100, and 97%, respectively. Interobserver agreement between two experienced observers was high (κ=0.83), whereas agreement between the experienced and the inexperienced observer was poor. CONCLUSION: The sensitivity of brain PET/CT for detecting brain metastases in lung cancer was above 70%, and the specificity was very high. Thus, PET/CT may be suitable for selecting patients for MRI in diagnostic centers that do not perform routine MRI in the pretherapeutic staging workup. The agreement among experienced readers was very high.