This study aimed to assess the clinical impact of ⁶⁸Ga-DOTATATE and ¹⁸F-fluorodeoxyglucose with respect to the management plan and to evaluate the prognostic value of both tracers. Methods: A total of 104 patients (55 males, 49 females; median age 58 years, range 20–90) with histopathologically proven NETs underwent both ⁶⁸Ga-DOTATATE and ¹⁸F-FDG PET/CT. Twenty-eight patients (26.9%) had poorly differentiated (PD) and 76 (73.1%), well-differentiated tumors (WD). PET/CT results and SUVs were compared with prognostic factors such as pathologic grading (G1, G2, G3), chromogranin A, and proliferation index (Ki67). Results: ⁶⁸Ga-DOTATATE and ¹⁸F-FDG PET/CT findings were discordant in 65 (62.5%) and concordant in 39 (37.5%) pts. PET/CT results changed the therapeutic plan in 84 (80.8%) pts. In 22 (21.1%) pts decision making was based on ¹⁸F-FDG findings, in 32 (30.8%) on findings with both radiotracers, and in 50 (48.1%) on ⁶⁸Ga-DOTATATE findings. The most frequent management decision based on ¹⁸F-FDG was initiation of chemotherapy (10 pts, 47.6%). The most common treatment decision due to ⁶⁸Ga-DOTATATE was initiation of peptide receptor radionuclide therapy (14 pts, 27.4%). In 11/28 (39.2%) pts with PD NETs the management decision was based only on ¹⁸F-FDG results. For ⁶⁸Ga-DOTATATE, SUV_max was higher for G1 and lower for G3 tumors (P = 0.012). However, no significant differences in ¹⁸F-FDG-derived SUVs were observed between different tumor grades (P = 0.38). Mann-Whitney test showed significant differences in ⁶⁸Ga-DOTATATE SUV_max between tumors with Ki5% (P = 0.004), without significance differences in ¹⁸F-FDG SUV_max. Log-rank analysis showed statistically significant differences in survival for patients with bone vs soft tissue or no metastasis for both ¹⁸F-FDG (P = 0.037) and ⁶⁸Ga-DOTATATE (P = 0.047). Overall survival was found to decline rapidly with increasing histological grade (P = 0.001), with estimated survival of 91 months for G1, 59 months for G2, and 48 months for G3. Conclusion: ¹⁸F-FDG PET/CT has no clinical impact in G1 NETs and moderate impact in G2 NETs. However in PD NETs, ¹⁸F-FDG PET/CT plays a significant clinical role in combination with ⁶⁸Ga-DOTATATE. ⁶⁸Ga DOTATATE SUV_max values relate to tumor grade and Ki67 index and can be used prognostically.

Rationale: ⁶⁸Ga-DOTATATE PET/CT scan is a widely accepted method for imaging of neuroendocrine tumours (NETs). This cross-sectional study was performed to review the first 8 years of patient data from a large ⁶⁸Ga-DOTATATE PET/CT database in order to establish the impact of the modality on patient treatment and survival. Methods: Demographic data, clinical outcome, survival, and change in management after ⁶⁸Ga-DOTATATE PET/CT were evaluated. Results: Between May 2005 and August 2013, 1258 ⁶⁸Ga-DOTATATE PET/CT scans were performed in 728 patients with confirmed or suspected NETs. In most patients the primary site was located in the midgut 26.4%. Analysis of NET grading in patients with known histopathological data revealed that 35.7% had NET grade G1, 12.2% G2 and 8.7% G3. The most common indications for ⁶⁸Ga-DOTATATE PET/CT were follow-up (24.4%) and initial tumour staging (23.4%). Of the 1258 ⁶⁸Ga-DOTATATE PET/CT scans completed, 75.7% were positive and 24.3% negative; there were 14 false positive and 29 false negative scans. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value were 97%, 95.1%, 96.6%, 98.5% and 90.4%, respectively. In 40.9% of patients, the treatment plan was changed after the scans, owing mainly to new, unexpected findings. Statistically significant differences in survival were shown between patients with G1, G2 and G3 grade tumours (p<0.0001), and also between patients with bone metastasis versus patients with soft tissue metastasis (p<0.0001). Conclusion: ⁶⁸Ga-DOTATATE PET/CT scan is safe and influences management in a large proportion of patients. Prognosis was dependent on tumour grade, and the presence of bone metastasis was associated with worse overall survival.

The aim of this study was to prospectively compare whole-body PET/MR imaging and PET/CT, qualitatively and quantitatively, in oncologic patients and assess the confidence and degree of inter- and intraobserver agreement in anatomic lesion localization. Fifty patients referred for staging with known cancers underwent PET/CT with low-dose CT for attenuation correction immediately followed by PET/MR imaging with 2-point Dixon attenuation correction. PET/CT scans were obtained according to standard protocols (56 ± 20 min after injection of an average 367 MBq of (18)F-FDG, 150 MBq of (68)Ga-DOTATATE, or 333.8 MBq of (18)F-fluoro-ethyl-choline; 2.5 min/bed position). PET/MR was performed with 5 min/bed position. Three dual-accredited nuclear medicine physicians/radiologists identified the lesions and assigned each to an exact anatomic location. The image quality, alignment, and confidence in anatomic localization of lesions were scored on a scale of 1-3 for PET/CT and PET/MR imaging. Quantitative analysis was performed by comparing the standardized uptake values. Intraclass correlation coefficients and the Wilcoxon signed-rank test were used to assess intra- and interobserver agreement in image quality, alignment, and confidence in lesion localization for the 2 modalities. Two hundred twenty-seven tracer-avid lesions were identified in 50 patients. Of these, 225 were correctly identified on PET/CT and 227 on PET/MR imaging by all 3 observers. The confidence in anatomic localization improved by 5.1% when using PET/MR imaging, compared with PET/CT. The mean percentage interobserver agreement was 96% for PET/CT and 99% for PET/MR imaging, and intraobserver agreement in lesion localization across the 2 modalities was 93%. There was 10% (5/50 patients) improvement in local staging with PET/MR imaging, compared with PET/CT. In this first study, we show the effectiveness of whole-body PET/MR imaging in oncology. There is no statistically significant difference between PET/MR imaging and PET/CT in respect of confidence and degree of inter- and intraobserver agreement in anatomic lesion localization. The PET data on both modalities were similar; however, the observed superior soft-tissue resolution of MR imaging in head and neck, pelvis, and colorectal cancers and of CT in lung and mediastinal nodal disease points to future tailored use in these locations.

The aim of the present study was to investigate the role of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in the diagnosis of post-transplant lymphoproliferative disorder (PTLD), a serious complication of solid organ and bone marrow transplant. Between January 2004 and January 2012, 40 patients (22 males; median age 52 ± 17.4 years, range 11-77 years) underwent (18)F-FDG PET/CT scans in our department for diagnostic evaluation of PTLD. Twenty-three (57.5%) patients had negative (18)F-FDG PET/CT and 17 (42.5%) had a positive examination. In five patients PET/CT revealed extranodal disease (adrenal, pleural, spleen, liver, lung, esophagus and bone involvement). On the basis of our results, (18)F-FDG PET/CT had a sensitivity of 88.2% (95% confidence interval [CI] 0.62-0.98), a specificity of 91.3% (CI 0.70-0.98), a positive predictive value of 88.2% (CI 0.62-0.98) and a negative predictive value of 91.3% (CI 0.70-0.98). The diagnostic performance of CT in patient-based analysis was: a sensitivity of 87.5% (CI 0.60-0.97), a specificity of 88.8% (CI 0.64-0.98), a positive predictive value of 87.5% (CI 0.60-0.97) and a negative predictive value of 88.8% (CI 0.64-0.98). PET/CT in five cases revealed more findings than CT, upstaging the disease, and revealed three extranodal findings, not visualized in conventional imaging. (18)F-FDG PET/CT plays a significant role in the setting of PTLD diagnosis, demonstrating its high accuracy in detecting PTLD.