7T Brain MRI Scan for Micro-brain Metastasis (microBM) Detection for Patients With Small-cell Lung Cancer (SCLC), Who Decline Prophylactic Cranial Irradiation (PCI)

Inclusion Criteria: * Patient must have a histologically confirmed diagnosis of small-cell lung cancer (SCLC). • Patient must have an MRI of the brain, performed within 4 weeks prior to consent, documenting no evidence of brain metastases or leptomeningeal disease. * Patient also must not have a history of brain metastases or leptomeningeal disease. * Patient must refuse PCI and agree to surveillance with brain MRI scans (1.5T/3T). * Patient must be ≥ 18 years of age. * Patient must have ECOG Performance Status of 0-2 * Patients must be able to tolerate the 7T MRI Exclusion Criteria: * Patient must not have a contraindication to an MRI, such as implanted metal devices or foreign bodies. * Patient must not have a contraindication to gadolinium contrast administration during MR imaging. * Patient must not have other metastatic malignancies requiring current active treatment. * Pregnant patients are excluded. Pregnancy status will be confirmed verbally.