RT Journal Article
SR Electronic
T1 Evaluation of the Outcome of Lung Nodules Missed on <sup>18</sup>F-FDG PET/MRI Compared with <sup>18</sup>F-FDG PET/CT in Patients with Known Malignancies
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP 15
OP 20
DO 10.2967/jnumed.115.162966
VO 57
IS 1
A1 Sawicki, Lino M.
A1 Grueneisen, Johannes
A1 Buchbender, Christian
A1 Schaarschmidt, Benedikt M.
A1 Gomez, Benedikt
A1 Ruhlmann, Verena
A1 Umutlu, Lale
A1 Antoch, Gerald
A1 Heusch, Philipp
YR 2016
UL http://jnm.snmjournals.org/content/57/1/15.abstract
AB The lower detection rate of 18F-FDG PET/MRI than 18F-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 18F-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 18F-FDG PET/CT and subsequent 18F-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 18F-FDG PET/CT and 18F-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 18F-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 18F-FDG PET/CT, 18F-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 18F-FDG PET/MRI. None of the missed lung nodules presented with focal tracer uptake on baseline imaging or follow-up 18F-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. Conclusion: Although most small lung nodules missed on 18F-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.