impact of fdg-pet and dynamic contrast-enhanced mri in comparison with dwi for n-staging in lung cancer patients

Background: regarding mediastinal n-staging in lung cancer patients, computed tomography (ct), magnetic resonance imaging (mri), and integrated 18fluorine-fluorodeoxyglucose-positron emission tomography/ct (18f-fdg-pet/ct) are the most widespread imaging methodologies in clinical routine. objectives: in order to further extract information from non-invasive staging, we evaluated the use of 18f-fdg-pet/ct and dynamic contrast enhanced (dce) and diffusion-weighted imaging (dwi) mri using histopathology as the diagnostic gold standard. patients and methods: a total number of 50 patients had undergone mri of the chest within two weeks prior to surgery for histopathological proof. dce-mri was evaluated on the basis of region of interest (roi)-based signal intensity/time (si/t) curves in the respective mediastinal lymph nodes (lns). in total, 28 lns could be allocated to the corresponding histopathological findings, as well as to corresponding findings in 18f-fdg-pet/ct. results: malignant lns presented with significantly higher fdg uptake in pet. significant differences between malignant and benign lns were found for dce-mri regarding the parameters maxe, 4-minutes value, se, ep and ep/maxe. in dwi-mri, malignant lns presented with significantly lower signal intensity compared to benign lns (p < 0.01). an apparent diffusion coefficient (adc) threshold of 1528mm2/s was found to exclude malignancy for lns that are above the threshold. conclusion: 18f-fdg-pet in addition with mri that includes dwi might improve mediastinal n-staging, which is of interest in cases of fdg-equivocal lns. an adc threshold of 1528 mm²/s might potentially help to further classify lns with indefinite pet-findings. dce-mri of mediastinal lns seems not yet to be approved for clinical routine.