title: Adrenal masses in patients with cancer: PET/CT characterization with combined CT histogram and standardized uptake value PET analysis.
abstract: OBJECTIVE
  Our purpose was to determine the diagnostic performance of 18F-FDG PET/CT for characterizing adrenal masses in patients with cancer, combining standardized uptake value (SUV) and CT histogram analysis.
  
  
  METHODS
  A total of 117 adrenal masses in 93 patients with cancer (61 men and 32 women; mean [± SD] age, 67.2 ± 10.3 years; range, 38-84 years) were evaluated with FDG PET/CT. Of the 117 lesions, 42 were malignant according to histopathologic analysis or size change, whereas 75 were benign on the basis of stability for 6 months. Size, mean attenuation value, percentage of negative pixels at CT histogram analysis, maximum SUV (SUV(max)), and average SUV were calculated for each adrenal lesion. Moreover, FDG adrenal uptake was compared with radioactivity of the aorta, liver, and spleen by calculating the SUV ratios of adrenal lesion to aorta, adrenal lesion to liver, and adrenal lesion to spleen. PET/CT value was assessed by using independent t tests and receiving operating characteristic (ROC) analysis.
  
  
  RESULTS
  There was a statistically significant difference in size, attenuation value, percentage of negative pixels, and SUV between benign and malignant masses. All malignant lesions showed FDG activity higher than that in liver, spleen, and aorta, with SUV(max) greater than 2.8 in all cases, whereas with the CT histogram analysis, all lesions with a percentage of negative pixels higher than 10% were benign. Combined SUV and CT histogram analysis yielded 100% sensitivity, 97.3% specificity, 95.7% positive predictive value, and 100% negative predictive value. At ROC analysis, combined SUV and CT histogram analysis (area under the ROC curve [AUC], 0.996) was more accurate than simple SUV(max) analysis (AUC, 0.961) and the combination of SUV(max) and attenuation value (AUC, 0.987).
  
  
  CONCLUSIONS
  The combination of SUV and CT histogram analysis allowed us to significantly improve the PET/CT diagnostic accuracy for characterizing adrenal lesions, leading to a significant reduction in the number of false-positive cases.
authors.affiliation: Regional Center of Nuclear Medicine, University of Pisa Medical School, Italy. marzioperri@hotmail.com
authors.forename: Marzio
authors.initials: M
authors.lastname: Perri
authors.forename: Paola
authors.initials: P
authors.lastname: Erba
authors.forename: Duccio
authors.initials: D
authors.lastname: Volterrani
authors.forename: Federica
authors.initials: F
authors.lastname: Guidoccio
authors.forename: Elena
authors.initials: E
authors.lastname: Lazzeri
authors.forename: Davide
authors.initials: D
authors.lastname: Caramella
authors.forename: Giuliano
authors.initials: G
authors.lastname: Mariani
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18