Editorial for “Chest PET/MRI in Solid Cancers: Comparing the Diagnostic Performance of a Free‐Breathing 3D Stack‐of‐Stars T1‐GRE (StarVIBE) Acquisition with that of a 3D‐T1‐GRE Volume Interpolated Breath‐Hold Examination (VIBE) for Chest Staging During Whole‐Body PET/MRI”

Editorial for “Chest PET/MRI in Solid Cancers: Comparing the Diagnostic Performance of a Free-Breathing 3D Stack-of-Stars T1-GRE (StarVIBE) Acquisition with that of a 3D-T1-GRE Volume Interpolated Breath-Hold Examination (VIBE) for Chest Staging During Whole-Body PET/MRI” Positron emission tomography/magnetic resonance imaging (PET/MRI) is an emerging hybrid imaging modality that offers potential advantages over PET/computed tomography (CT), including superior soft tissue characterization, better image coregistration, and reduced radiation exposure. Despite being introduced back in 2010 and being approved for clinical use in the United States since 2011, several pragmatic challenges have limited the widespread integration of PET/MRI into clinical practice, such as system and operational costs, provider awareness, and billing issues, but these may change with increased adoption over time, and a steady transition from a predominant research focus to clinical applications can already be seen at a number of medical imaging centers. In a recent review that combined the results of 46 comparative peer-reviewed clinical studies for a total of 2340 patients, PET/MRI was shown to perform equivalently to PET/CT for most types of cancer. One of the hurdles of PET/MRI in the oncologic setting has been the detection of pulmonary lesions, especially for small, F-fluorodeoxyglucose (FDG) non-avid lung nodules. As this limitation also affects the nondiagnostic CT component of PET/CT, additional diagnostic chest CT may currently be considered a necessary part of cancer staging, at the expense of higher radiation exposure and extra time and cost. Recent implementations of non-Cartesian k-space trajectory MR pulse sequences have been improving image quality for pulmonary disease assessment, and lung nodule detection and characterization capabilities have reached a level comparable of standard-dose CT according to some investigations. Should these results be replicated in larger clinical studies and such lung-optimized techniques become widely available, pulmonary MRI might turn out to be a viable radiation-free alternative to CT in the future, especially for cancer patients who undergo repeated examinations to evaluate treatment response and long-term surveillance. In this issue of JMRI, Vermersch et al incorporated a free-breathing radial 3D gradient echo pulse sequence with stack-of-stars sampling (StarVIBE) in the oncologic wholebody PET/MRI acquisition protocol, and compared its diagnostic performance for thoracic staging with a more standard breath-hold Cartesian 3D gradient echo pulse sequence (VIBE), using CT as the reference standard for pulmonary nodule detection and multidisciplinary tumor board consensus for determining the metastatic nature of all chest lesions, taking into account histopathology, F-FDG avidity, and/or lesion behavior during follow-up imaging. In this retrospective study, StarVIBE was particularly advantageous for small lung nodules, with improvement in the detectability of lesions shorter than 5 mm compared to previously published data, benefiting from the thinner slice thickness and reduced motion sensitivity achievable due to the acquisition scheme. Also of note, 90% of metastatic lung nodules were detected using StarVIBE, including 81% of those smaller than 5 mm. Overall, StarVIBE was superior to either VIBE or PET regarding pulmonary metastasis detection, both on per-lesion and per-patient bases. StarVIBE performance also surpassed that of VIBE for nodal disease and that of PET for bone involvement on a per-lesion basis, outperforming both techniques in