PET/CT Outperforms PET or CT Alone in Imaging Non–Small-Cell Lung Cancer

ESSEN, Germany-Positronemission tomography-computed tomography(PET/CT) is significantlymore accurate than CT alone, PETalone, and side-by-side CT and PETfor evaluating the TNM stage ofvarious malignant diseases. This diagnosticadvantage translates intotreatment plan changes in a substantialnumber of patients, according toresearcher Gerald Antoch, MD, andcolleagues at University HospitalEssen in Germany. Dr. Antoch reportedhis group's findings at the 90thScientific Assembly and Annual Meetingof the Radiological Society ofNorth America (abstract SSA24-02).The researchers viewed scans from260 consecutive patients (167 female)with different oncological diseaseswho had undergone 2-fluorodeoxyglucose(FDG)-PET/CT for tumorstaging. A total of 112 patients wereimaged for primary tumor staging and148 were imaged for suspected recurrent disease Dr. Antoch said.The majority of patients had malignantnon-small-cell lung carcinoma,followed by head and neck tumors,gastrointestinal tumors, andothers. Investigators performed PET/CT with an axial field-of-view fromthe head to the upper thigh, usingintravenous contrast CT to obtaindiagnostic data.Two nuclear medicine specialistsviewed the PET-alone images. Theyevaluated the images first qualitativelyby the areas of increased glucosemetabolism, then quantitatively by thestandard uptake value (SUV).An SUV cutoff of 2.5 for malignancywas applied for all organs exceptthe liver, for which the cutoffvalue was 3.5. The difference in cutoffvalues was based on an analysis of theliterature that showed generally higherFDG uptake in the liver than in therest of the body organs, Dr. Antochtold Oncology News International.Two radiologists examined the CTimages and determined whetherlymph nodes were metastatic, basedon their size. Side-by-side images wereevaluated by radiologists and nuclearmedicine specialists on two differentscreens: CT on the right screen, PETon the left. The images were purposelymisregistered to ensure a degree ofobjectivity.The same radiologists and nuclearmedicine specialists reviewed thefused images 1 month after the sideby-side image analysis. Increased glucosemetabolism was again used todetermine pathology.The researchers performed aseparate analysis for the T-, N-, andM-stages and also determined the impactof PET/CT on patient management.Histopathology was the standardof reference for 77 patients forthe T-stage, 72 patients for theN-stage, and 57 patients for theM-stage. For all other patients, a mean clinical follow-up of 311 days servedas the standard of reference.TNM StagingSignificantly ImprovedFused PET/CT proved significantlymore accurate in assessing the overallTNM stage compared with CTalone, PET alone, and side-by-side CTplus PET. Among the 260 patients,84% were correctly staged with PET/CT, vs 76 % with side-by-side CT plusPET, 64% with PET alone, and 63%with CT alone.Sensitivities and specificities forcharacterization of the N-stage were92% and 93%, respectively, for PET/CT, 88% and 89% for side-by-sideCT plus PET, 85% and 88% for PET,and 64% and 83% for CT.Sensitivities and specificities for assessmentof the M-stage were 94%and 97%, respectively, with PET/CT,92% and 96% with side-by-side CTplus PET, 78% and 99% with PET,and 82% and 95% with CT."The most important point, however,is whether PET/CT had an impacton patient management," Dr.Antoch said. "Does it change patienttherapy from palliative to curative,from curative to palliative? Does itchange the surgical approach from extendedsurgery to limited surgery?"The investigators found that, indeed,PET/CT did impact patient management:Combined PET/CT affected thetreatment plan for 17% of patientscompared with PET alone, for 15% ofpatients compared with CT alone, andfor 6% of patients compared withside-by-side CT plus PET.