title: Impact of attenuation correction on the accuracy of FDG-PET in patients with abdominal tumors: a free-response ROC analysis.
abstract: The aim of this study was to evaluate image quality and lesion detectability with and without attenuation correction in patients with abdominal tumors, using a free-response receiver operating characteristic (FROC) methodology. Thirty-four patients with various abdominal tumors were evaluated (11 men, 23 women, median age 48 years). Whole-body emission scans were performed 68 min (35-102 min) after intravenous injection of 4.3 MBq/kg fluorine-18 fluorodeoxyglucose (FDG). Images were reconstructed using the OS-EM algorithm and corrected for attenuation either using postinjection singles transmission (n=27) or by calculation and body outline (n=7). Total scan duration did not exceed 70 min. Studies were read independently by four observers unaware of any clinical data. The uncorrected (UC) images were systematically read before the attenuation-corrected (AC) images. All studies were given an image quality score ranging from 1 (unreadable) to 5 (excellent). Each focus of increased activity was then localized and given a probability of malignancy using a five-point scale. The average image quality score was similar for both UC and AC images. At the time of the positron emission tomography (PET) scans, 127 lesions (63 liver metastases, 9 retroperitoneal lesions, 50 peritoneal or bowel lesions, and 5 pancreatic carcinomas) were revealed by pathological or correlative studies. The areas under the FROC curves were consistently greater for AC images (range 0.8663-0.8867) than for UC images (range 0.7774 -0.8613). Overall, the difference between the AC images and the UC images was significant (P=0.019). In particular, correction for attenuation increased the sensitivity regardless of the location of the lesions. In conclusion, correction for attenuation significantly improves the diagnostic accuracy of FDG-PET for abdominal staging of neoplasms, without impairing the image quality.
authors.affiliation: Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, USA.
authors.forename: R
authors.initials: R
authors.lastname: Hustinx
authors.forename: R J
authors.initials: RJ
authors.lastname: Dolin
authors.forename: F
authors.initials: F
authors.lastname: Bénard
authors.forename: A
authors.initials: A
authors.lastname: Bhatnagar
authors.forename: D
authors.initials: D
authors.lastname: Chakraborty
authors.forename: R J
authors.initials: RJ
authors.lastname: Smith
authors.forename: S
authors.initials: S
authors.lastname: Jang
authors.forename: A
authors.initials: A
authors.lastname: Alavi
mesh_terms: D000008:Abdominal Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D014055:Tomography, Emission-Computed
chemical_list: D019788:Fluorodeoxyglucose F18