title: 68Ga-DOTATATE PET/CT for the detection of inflammation of large arteries: correlation with18F-FDG, calcium burden and risk factors.
abstract: BACKGROUND
  Ga-[1,4,7,10-tetraazacyclododecane-N,N',N″,N'″-tetraacetic acid]-d-Phe1,Tyr3-octreotate (DOTATATE) positron emission tomography (PET) is commonly used for the visualization of somatostatin receptor (SSTR)-positive neuroendocrine tumors. SSTR is also known to be expressed on macrophages, which play a major role in inflammatory processes in the walls of coronary arteries and large vessels. Therefore, imaging SSTR expression has the potential to visualize vulnerable plaques. We assessed 68Ga-DOTATATE accumulation in large vessels in comparison to 18F-2-fluorodeoxyglucose (FDG) uptake, calcified plaques (CPs), and cardiovascular risk factors.
  
  
  METHODS
  Sixteen consecutive patients with neuroendocrine tumors or thyroid cancer underwent both 68Ga-DOTATATE and 18F-FDG PET/CT for staging or restaging purposes. Detailed clinical data, including common cardiovascular risk factors, were recorded. For a separate assessment, they were divided into a high-risk and a low-risk group. In each patient, we calculated the maximum target-to-background ratio (TBR) of eight arterial segments. The correlation of the TBRmean of both tracers with risk factors including plaque burden was assessed.
  
  
  RESULTS
  The mean TBR of 68Ga-DOTATATE in all large arteries correlated significantly with the presence of CPs (r = 0.52; p < 0.05), hypertension (r = 0.60; p < 0.05), age (r = 0.56; p < 0.05), and uptake of 18F-FDG (r = 0.64; p < 0.01). There was one significant correlation between 18F-FDG uptake and hypertension (0.58; p < 0.05). Out of the 37 sites with the highest focal 68Ga-DOTATATE uptake, 16 (43.2%) also had focal 18F-FDG uptake. Of 39 sites with the highest 18F-FDG uptake, only 11 (28.2%) had a colocalized 68Ga-DOTATATE accumulation.
  
  
  CONCLUSIONS
  In this series of cancer patients, we found a stronger association of increased 68Ga-DOTATATE uptake with known risk factors of cardiovascular disease as compared to 18F-FDG, suggesting a potential role for plaque imaging in large arteries. Strikingly, we found that focal uptake of 68Ga-DOTATATE and 18F-FDG does not colocalize in a significant number of lesions.
authors.affiliation: Department of Nuclear Medicine, University of Wuerzburg, Oberdürrbacher Str, 6, Wuerzburg, D-97080, Germany. Samnick_S@klinik.uni--wuerzburg.de.
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.forename: Samuel
authors.initials: S
authors.lastname: Samnick
authors.forename: Constantin
authors.initials: C
authors.lastname: Lapa
authors.forename: Ina
authors.initials: I
authors.lastname: Israel
authors.forename: Andreas K
authors.initials: AK
authors.lastname: Buck
authors.forename: Michael C
authors.initials: MC
authors.lastname: Kreissl
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bauer