Whole-body bone marrow MRI as used in this study is an effective method for evaluating the entire skeletal system in patients with suspected metastatic disease.

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.

FDG-PET allows for prediction of treatment response by the level of FDG uptake in terms of SUV at baseline and after each cycle of chemotherapy. Moreover, relative changes in SUV after the first and second cycle are a strong predictor of response. Thus, FDG-PET may be helpful for individual treatment stratification in breast cancer patients.

WB-MRI and PET-CT are reliable imaging modalities for tumor staging. WB-MRI is highly sensitive in detecting distant metastases; PET-CT is superior in lymph node staging. PAT makes high-resolution WB-MRI feasible within less than 1 hour.

In this study (68)Ga-DOTA-TATE PET proved clearly superior to (18)F-DOPA PET for detection and staging of NET. (18)F-DOPA uptake tended to be increased in those patients with elevated plasma serotonin. We conclude that (18)F-DOPA PET should be employed in patients with NET with negative (68)Ga-DOTA-TATE PET and elevated plasma serotonin.

The diagnostic accuracy of screening for bone metastases was evaluated using whole-body magnetic resonance imaging (WB-MRI) compared with combined fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) (FDG-PET-CT). In a prospective, blinded study, 30 consecutive patients (18 female, 12 male; 24-76 years) with different oncological diseases and suspected skeletal metastases underwent FDG-PET-CT as well as WB-MRI with the use of parallel imaging (PAT). With a 32-channel scanner, coronal imaging of the entire body and sagittal imaging of the complete spine was performed using T1-weighted and short tau inversion recovery (STIR) sequences in combination. PET-CT was conducted using a low-dose CT for attenuation correction, a PET-emission scan and diagnostic contrast-enhanced CT scan covering the thorax, abdomen and pelvis. Two radiologists read the MRI scans, another radiologist in combination with a nuclear medicine physician read the PET-CT scans, each in consensus. The standard of reference was constituted by radiological follow-up within at least 6 months. In 28 patients, 102 malignant and 25 benign bone lesions were detected and confirmed. WB-MRI showed a sensitivity of 94% (96/102), PET-CT exams achieved 78% (79/102; P<0.001). Specificities were 76% (19/25) for WB-MRI and 80% (20/25) for PET-CT (P>0.05). Diagnostic accuracy was 91% (115/127) and 78% (99/127; P<0.001), respectively. Cut-off size for the detection of malignant bone lesions was 2 mm for WB-MRI and 5 mm for PET-CT. WB-MRI revealed ten additional bone metastases due to the larger field of view. In conclusion, WB-MRI and FDG-PET-CT are robust imaging modalities for a systemic screening for metastatic bone disease. PAT allows WB-MRI bone marrow screening at high spatial resolution and with a diagnostic accuracy superior to PET-CT.

Based on our findings, differentiation between benign prostatic changes, such as benign prostatic hyperplasia or prostatitis, and prostate cancer is feasible in the majority of cases when image interpretation is primarily based on qualitative characteristics. SUV(max) may serve as guidance. False positive findings may occur due to an overlap of (11)C-choline uptake between benign and malignant processes. By providing functional information regarding both the primary malignancy and its metastases, (11)C-choline PET may prove to be a useful method for staging prostate cancer.

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