title: Comparison of the Impact of 68Ga-DOTATATE and 18F-FDG PET/CT on Clinical Management in Patients with Neuroendocrine Tumors.
abstract: This study aimed to assess the clinical impact of68Ga-DOTATATE and18F-FDG with respect to the management plan and to evaluate the prognostic value of both tracers.
  
  
  METHODS
  A total of 104 patients (55 male and 49 female; median age, 58 y; range, 20-90 y) with histologically proven neuroendocrine tumors (NETs) underwent both68Ga-DOTATATE and18F-FDG PET/CT. Twenty-eight patients (26.9%) had poorly differentiated tumors, and 76 (73.1%) had well-differentiated tumors. PET/CT results and SUVs were compared with prognostic factors such as histologic grade (G1, G2, or G3, for low-grade [well differentiated], intermediate-grade [moderately differentiated], and high-grade [poorly differentiated], respectively), chromogranin A, and proliferation index (Ki-67).
  
  
  RESULTS
  The68Ga-DOTATATE and18F-FDG PET/CT findings were discordant in 65 patients (62.5%) and concordant in 39 patients (37.5%). The results changed the therapeutic plan in 84 patients (80.8%). In 22 patients (21.1%), decision making was based on the18F-FDG findings; in 32 (30.8%), on the findings with both radiotracers; and in 50 (48.1%), on the68Ga-DOTATATE findings. The most frequent management decision based on18F-FDG was initiation of chemotherapy (10 patients, 47.6%). The most common treatment decision due to68Ga-DOTATATE was initiation of peptide receptor radionuclide therapy (14 patients, 27.4%). In 11 (39.2%) of 28 patients with poorly differentiated NETs, the management decision was based on only the18F-FDG results. For68Ga-DOTATATE, SUVmaxwas higher for G1 tumors and lower for G3 tumors (P = 0.012). However, no significant differences in18F-FDG-derived SUVs were observed between different grades (P = 0.38). The Mann-Whitney test showed significant differences in68Ga-DOTATATE SUVmaxbetween tumors with a Ki-67 of less than 5% and tumors with a Ki-67 of more than 5% (P = 0.004), without significance differences in18F-FDG SUVmaxLog-rank analysis showed statistically significant differences in survival for patients with bone metastasis versus soft-tissue or no metastasis for both18F-FDG (P = 0.037) and68Ga-DOTATATE (P = 0.047). Overall survival declined rapidly with increasing grade (P = 0.001), at an estimated 91 mo for G1, 59 mo for G2, and 48 mo for G3.
  
  
  CONCLUSIONS
  18F-FDG PET/CT had no clinical impact on G1 NETs and a moderate impact on G2 NETs. However, in poorly differentiated NETs,18F-FDG PET/CT plays a significant clinical role in combination with68Ga-DOTATATE.68Ga DOTATATE SUVmaxrelates to grade and Ki-67 and can be used prognostically.
authors: Institute of Nuclear Medicine, University College London Hospital, London, United Kingdom; and m_panagiotidis@yahoo.com.
authors: Emmanouil
authors: E
authors: Panagiotidis
authors: Institute of Nuclear Medicine, University College London Hospital, London, United Kingdom; and.
authors: Alshaima
authors: A
authors: Alshammari
authors: Institute of Nuclear Medicine, University College London Hospital, London, United Kingdom; and.
authors: Sofia
authors: S
authors: Michopoulou
authors: Institute of Nuclear Medicine, University College London Hospital, London, United Kingdom; and.
authors: Evangelia
authors: E
authors: Skoura
authors: Neuroendocrine Tumour Unit, ENETS Centre of Excellence, Royal Free Hospital, London, United Kingdom.
authors: Keval
authors: K
authors: Naik
authors: Neuroendocrine Tumour Unit, ENETS Centre of Excellence, Royal Free Hospital, London, United Kingdom.
authors: Emmanouil
authors: E
authors: Maragkoudakis
authors: Neuroendocrine Tumour Unit, ENETS Centre of Excellence, Royal Free Hospital, London, United Kingdom.
authors: Mullan
authors: M
authors: Mohmaduvesh
authors: Institute of Nuclear Medicine, University College London Hospital, London, United Kingdom; and.
authors: Mohammed
authors: M
authors: Al-Harbi
authors: Institute of Nuclear Medicine, University College London Hospital, London, United Kingdom; and.
authors: Maria
authors: M
authors: Belda
authors: Neuroendocrine Tumour Unit, ENETS Centre of Excellence, Royal Free Hospital, London, United Kingdom.
authors: Martyn E
authors: ME
authors: Caplin
authors: Neuroendocrine Tumour Unit, ENETS Centre of Excellence, Royal Free Hospital, London, United Kingdom.
authors: Christos
authors: C
authors: Toumpanakis
authors: Institute of Nuclear Medicine, University College London Hospital, London, United Kingdom; and.
authors: Jamshed
authors: J
authors: Bomanji
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000628:therapy*; D009942:Organometallic Compounds; D010346:Patient Care Management / Q000706:statistics & numerical data*; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D015995:Prevalence; D011379:Prognosis; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016896:Treatment Outcome; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; C513399:gallium Ga 68 dotatate
keywords: 18F-FDG PET/CT; 68Ga-DOTATATE; clinical impact; neuroendocrine tumors; prognosis