title: Comparison of 68Ga-DOTANOC PET/CT and contrast-enhanced CT in localisation of tumours in ectopic ACTH syndrome.
abstract: BACKGROUND
  Localising ectopic adrenocorticotrophic hormone (ACTH) syndrome (EAS) tumour source is challenging. Somatostatin receptor-based PET imaging has shown promising results, but the data is limited to case reports and small case series. We reviewed here the performance of (68)Ga-DOTANOC positron emission tomography (PET)/computed tomography (CT) and contrast-enhanced CT (CECT) in our cohort of 12 consecutive EAS patients.
  
  
  METHODS
  Retrospective data analysis of 12 consecutive patients of EAS presenting to a single tertiary care centre in a period between January 2013 and December 2014 was done. CECT and (68)Ga-DOTANOC PET/CT were reported (blinded) by an experienced radiologist and a nuclear medicine physician, respectively. The performance of CECT and (68)Ga-DOTANOC PET/CT was compared.
  
  
  RESULTS
  Tumours could be localised in 11 out of 12 patients at initial presentation (overt cases), whereas in one patient, tumour remained occult. Thirteen lesions were identified in 11 patients as EAS source (true positives). CECT localised 12 out of these 13 lesions (sensitivity 92.3%) and identified five false-positive lesions (positive predictive value (PPV) 70.5%). Compared with false-positive lesions, true-positive lesions had greater mean contrast enhancement at 60s (33.2 vs 5.6 Hounsfield units (HU)). (68)Ga-DOTANOC PET/CT was able to identify 9 out of 13 lesions (sensitivity 69.2%) and reported no false-positive lesions (PPV 100%).
  
  
  CONCLUSIONS
  CECT remains the first-line investigation in localisation of EAS. The contrast enhancement pattern on CECT can further aid in characterisation of the lesions. (68)Ga-DOTANOC PET/CT can be added to CECT, to enhance positive prediction of the suggestive lesions.
authors.affiliation: Department of EndocrinologySeth G S Medical College and KEM Hospital, Mumbai, Maharashtra, India manjunath.r.goroshi@gmail.com.
authors.forename: Majunath R
authors.initials: MR
authors.lastname: Goroshi
authors.affiliation: Department of EndocrinologySeth G S Medical College and KEM Hospital, Mumbai, Maharashtra, India.
authors.forename: Swati S
authors.initials: SS
authors.lastname: Jadhav
authors.affiliation: Department of EndocrinologySeth G S Medical College and KEM Hospital, Mumbai, Maharashtra, India.
authors.forename: Anurag R
authors.initials: AR
authors.lastname: Lila
authors.affiliation: Department of EndocrinologySeth G S Medical College and KEM Hospital, Mumbai, Maharashtra, India.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Kasaliwal
authors.affiliation: Department of EndocrinologySeth G S Medical College and KEM Hospital, Mumbai, Maharashtra, India.
authors.forename: Shruti
authors.initials: S
authors.lastname: Khare
authors.affiliation: Department of EndocrinologySeth G S Medical College and KEM Hospital, Mumbai, Maharashtra, India.
authors.forename: Chaitanya G
authors.initials: CG
authors.lastname: Yerawar
authors.affiliation: Department of RadiologySeth G S Medical College and KEM Hospital, Mumbai, Maharashtra, India.
authors.forename: Priya
authors.initials: P
authors.lastname: Hira
authors.affiliation: Ruby Hall ClinicPune, Maharashtra, India.
authors.forename: Uday
authors.initials: U
authors.lastname: Phadke
authors.affiliation: Department of Nuclear Medicine and Positron Emission Tomography/Computed TomographyJaslok Hospital and Research Centre, Mumbai, Maharashtra, India.
authors.forename: Hina
authors.initials: H
authors.lastname: Shah
authors.affiliation: Department of Nuclear Medicine and Positron Emission Tomography/Computed TomographyJaslok Hospital and Research Centre, Mumbai, Maharashtra, India.
authors.forename: Vikram R
authors.initials: VR
authors.lastname: Lele
authors.affiliation: Radiation Medicine CentreBhabha Atomic Research Centre, Tata Memorial Centre, Annexe, Parel, Mumbai, Maharashtra, India.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Malhotra
authors.affiliation: Department of EndocrinologySeth G S Medical College and KEM Hospital, Mumbai, Maharashtra, India.
authors.forename: Tushar
authors.initials: T
authors.lastname: Bandgar
authors.affiliation: Department of EndocrinologySeth G S Medical College and KEM Hospital, Mumbai, Maharashtra, India.
authors.forename: Nalini S
authors.initials: NS
authors.lastname: Shah
keywords: 68Ga-DOTANOC PET/CT; CECT; Cushing’s syndrome; DIPNECH; EAS; lung carcinoid; pulmonary paraganglioma