title: Evaluation of the Outcome of Lung Nodules Missed on 18F-FDG PET/MRI Compared with 18F-FDG PET/CT in Patients with Known Malignancies.
abstract: The lower detection rate of (18)F-FDG PET/MRI than (18)F-FDG PET/CT regarding small lung nodules should be considered in the staging of malignant tumors. The purpose of this study was to evaluate the outcome of these small lung nodules missed by (18)F-FDG PET/MRI.
  
  
  METHODS
  Fifty-one oncologic patients (mean age ± SD, 56.6 ± 14.0 y; 29 women, 22 men; tumor stages, I [n = 7], II [n = 7], III [n = 9], IV [n = 28]) who underwent (18)F-FDG PET/CT and subsequent (18)F-FDG PET/MRI on the same day were retrospectively enrolled. Images were analyzed by 2 interpreters in random order and separate sessions with a minimum of 4 wk apart. A maximum of 10 lung nodules was identified for each patient on baseline imaging. The presence, size, and presence of focal tracer uptake was noted for each lung nodule detected on (18)F-FDG PET/CT and (18)F-FDG PET/MRI using a postcontrast T1-weighted 3-dimensional gradient echo volume-interpolated breath-hold examination sequence with fat suppression as morphologic dataset. Follow-up CT or (18)F-FDG PET/CT (mean time to follow-up, 11 mo; range, 3-35 mo) was used as a reference standard to define each missed nodule as benign or malignant based on changes in size and potential new tracer uptake. Nodule-to-nodule comparison between baseline and follow-up was performed using descriptive statistics.
  
  
  RESULTS
  Out of 134 lung nodules found on (18)F-FDG PET/CT, (18)F-FDG PET/MRI detected 92 nodules. Accordingly, 42 lung nodules (average size ± SD, 3.9 ± 1.3 mm; range, 2-7 mm) were missed by (18)F-FDG PET/MRI. None of the missed lung nodules presented with focal tracer uptake on baseline imaging or follow-up (18)F-FDG PET/CT. Thirty-three out of 42 missed lung nodules (78.6%) in 26 patients were rated benign, whereas 9 nodules (21.4%) in 4 patients were rated malignant. As a result, 1 patient required upstaging from tumor stage I to IV.
  
  
  CONCLUSIONS
  Although most small lung nodules missed on (18)F-FDG PET/MRI were found to be benign, there was a relevant number of undetected metastases. However, in patients with advanced tumor stages the clinical impact remains controversial as upstaging is usually more relevant in lower stages.
authors.affiliation: Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, Dusseldorf, Germany linomorris.sawicki@med.uni-duesseldorf.de.
authors.forename: Lino M
authors.initials: LM
authors.lastname: Sawicki
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, Medical Faculty, University Duisburg-Essen, Essen, Germany; and.
authors.forename: Johannes
authors.initials: J
authors.lastname: Grueneisen
authors.affiliation: Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, Dusseldorf, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Buchbender
authors.affiliation: Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, Dusseldorf, Germany.
authors.forename: Benedikt M
authors.initials: BM
authors.lastname: Schaarschmidt
authors.affiliation: Department of Nuclear Medicine, Medical Faculty, University Duisburg-Essen, Essen, Germany.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Gomez
authors.affiliation: Department of Nuclear Medicine, Medical Faculty, University Duisburg-Essen, Essen, Germany.
authors.forename: Verena
authors.initials: V
authors.lastname: Ruhlmann
authors.affiliation: Department of Diagnostic and Interventional Radiology and Neuroradiology, Medical Faculty, University Duisburg-Essen, Essen, Germany; and.
authors.forename: Lale
authors.initials: L
authors.lastname: Umutlu
authors.affiliation: Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, Dusseldorf, Germany.
authors.forename: Gerald
authors.initials: G
authors.lastname: Antoch
authors.affiliation: Department of Diagnostic and Interventional Radiology, Medical Faculty, University Dusseldorf, Dusseldorf, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Heusch
mesh_terms: D005188:False Negative Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: MRI; PET/CT; PET/MRI; lung; nodules