PET/CT versus MRI for diagnosis, staging, and follow-up of lung cancer

Positron emission tomography / computed tomography (PET/CT), with its metabolic data of ¹⁸F-fluorodeoxyglucose (FDG) cellular uptake in addition to morphologic CT data, is an established technique for staging of lung cancer and has higher sensitivity and accuracy for lung nodule characterization than conventional approaches. Its strength extends outside the chest, with unknown metastases detected or suspected metastases excluded in a significant number of patients. Lastly, PET/CT is used in the assessment of therapy response. Magnetic resonance imaging (MRI) in the chest has been difficult to establish, but with the advent of new sequences is starting to become an increasingly useful alternative to conventional approaches. Diffusion-weighted MRI (DWI) is useful for distinguishing benign and malignant pulmonary nodules, has high sensitivity and specificity for nodal staging, and is helpful for evaluating an early response to systemic chemotherapy. Whole-body MRI/PET promises to contribute additional information with its higher soft-tissue contrast and much less radiation exposure than PET/CT and has become feasible for fast imaging and can be used for cancer staging in patients with a malignant condition.