title: Preoperative characterization of indeterminate large adrenal masses with dual tracer PET-CT using fluorine-18 fluorodeoxyglucose and gallium-68-DOTANOC: initial results.
abstract: OBJECTIVE
  We aimed to evaluate the usefulness of dual tracer positron emission tomography-computed tomography (PET-CT) with flourine-18 fluorodeoxyglucose (18F-FDG) and gallium-68 [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-1-NaI3-octreotide (68Ga-DOTANOC) in preoperative characterization of large indeterminate adrenal masses.
  
  
  METHODS
  Ten patients (four males, six females; median age, 35 years) with indeterminate, large (≥4 cm) adrenal masses were included in this prospective study. All patients underwent both 18F-FDG PET-CT and 68Ga-DOTANOC PET-CT within one week. Images were evaluated both visually and semi-quantitatively, with standardized uptake value (SUVmax) and SUVratio (SUVmax) of tumor/SUVmax) of mediastinum). Based on differential uptake pattern on 18F-FDG and 68Ga-DOTANOC, lesions were classified as cortical (18F-FDG>68Ga-DOTANOC), medullary (68Ga-DOTANOC>18F-FDG), or indeterminate (18F-FDG=68Ga-DOTANOC). Histopathology was taken as reference standard. Receiver operating characteristic (ROC) analysis was performed to find a cut-off of SUVmax) and SUVratio to differentiate cortical and medullary lesions.
  
  
  RESULTS
  On histopathology, eight lesions were adrenocortical carcinomas, one was benign pheochromocytoma, and one was malignant pheochromocytoma. Visually, 18F-FDG PET-CT was positive in all ten lesions, while 68Ga-DOTANOC PET-CT was positive in two, both of which were pheochromocytomas. On SUVmax) based analysis, nine lesions were cortical and one was medullary. On ROC analysis, a SUVmax) cut-off of > 2.3 was obtained for 18F-FDG PET-CT and 3.6 for 68Ga-DOTANOC PET-CT for differentiating adrenal cortical and medullary lesions. The cut-off for SUVratio was 4.5 on 18F-FDG PET-CT and 11.1 on 68Ga-DOTANOC PET-CT.
  
  
  CONCLUSIONS
  These preliminary results demonstrate that dual tracer PET-CT using 18F-FDG and 68Ga-DOTANOC could be informative in the preoperative characterization of large indeterminate adrenal masses.
authors: Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors: Niraj
authors: N
authors: Naswa
authors: Punit
authors: P
authors: Sharma
authors: Ramya
authors: R
authors: Soundararajan
authors: Manish
authors: M
authors: Patnecha
authors: Sneh
authors: S
authors: Lata
authors: Rakesh
authors: R
authors: Kumar
authors: Arun
authors: A
authors: Malhotra
authors: Chandrasekhar
authors: C
authors: Bal
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging*; D000328:Adult; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D064847:Multimodal Imaging / Q000379:methods; D009942:Organometallic Compounds; D049268:Positron-Emission Tomography / Q000379:methods*; D011300:Preoperative Care / Q000379:methods*; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: C504894:68Ga-DOTANOC; D009942:Organometallic Compounds; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18