Advanced Magnetic Resonance Imaging Techniques in Management of Brain Metastases

Abstract

Brain metastases are the most common intracranial tumors and occur in 20–40% of all cancer patients. Lung cancer, breast cancer, and melanoma are the most frequent primary cancers to develop brain metastases. Treatment options include surgical resection, whole brain radiotherapy, stereotactic radiosurgery, and systemic treatment such as targeted or immune therapy. Anatomical magnetic resonance imaging (MRI) of the tumor (in particular post-Gadolinium T 1 -weighted and T 2 -weighted FLAIR) provide information about lesion morphology and structure, and are routinely used in clinical practice for both detection and treatment response evaluation for brain metastases. Advanced MRI biomarkers that characterize the cellular, biophysical, micro-structural and metabolic features of tumors have the potential to improve the management of brain metastases from early detection and diagnosis, to evaluating treatment response. Magnetic resonance spectroscopy (MRS), chemical exchange saturation transfer (CEST), quantitative magnetization transfer (qMT), diffusion-based tissue microstructure imaging, trans-membrane water exchange mapping, and magnetic susceptibility weighted imaging (SWI) are advanced MRI techniques that will be reviewed in this article as they pertain to brain metastases.

Advanced Imaging of Brain Metastases: From Augmenting Visualization and Improving Diagnosis to Evaluating Treatment Response

“…However, both methods are limited in spatial resolution and coverage, making MRS susceptible to partial volume effects. Diagnostic accuracy of MRS can also be limited by sampling error, especially with heterogeneous lesions (8). In general, a multi-voxel technique is recommended for evaluation of heterogeneous tumors or multiple lesions in order to minimize sampling error from a specific area of a lesion (26).…”

“…More recently, advanced MRI techniques that have moved beyond anatomical imaging are available to characterize microstructures, cellularity, physiology, perfusion, and metabolism. Changes in these attributes may supersede perceivable macroscopic anatomic changes and can serve as potential biomarkers for monitoring treatment effect, recurrence, and disease progression (8).…”

Clinical Value of Susceptibility Weighted Imaging of Brain Metastases

“…For monitoring of brain metastases multiparametric anatomical imaging is performed in the routine clinical setting (38). Further advanced sequences including chemical exchange saturation transfer imaging (CEST), magnetization transfer (MT) imaging and MR spectroscopy (MRS) have also been assessed regarding their clinical value and have recently been reviewed (39). In the context of neurooncology MT imaging could differentiate glioblastoma from brain metastasis (40).…”

Current multidisciplinary management of brain metastases

“…These MRI characteristics, however, are not pathognomonic for BMs, and the differential diagnosis includes primary brain tumors, infection, demyelinating disease, and vascular abnormalities. Additional MRI sequences and other imaging modalities can be helpful in identifying and evaluating BMs to better differentiate them from other pathologies, such as diffusion‐weighted MRI, diffusion‐tensor MRI, MR spectroscopy, MR perfusion, and positron emission tomography (PET) …”

“…Cancer April 1, 2020 and evaluating BMs to better differentiate them from other pathologies, such as diffusion-weighted MRI, diffusion-tensor MRI, MR spectroscopy, MR perfusion, and positron emission tomography (PET). [7][8][9] PROGNOSTIC ASSESSMENT Historically, untreated patients with BMs experienced a 1-month to 2-month median overall survival (OS), 10 and whole-brain radiation therapy (WBRT) extended this to approximately 4 to 6 months. 11 With modern systemic therapies, supportive care, and early hospice/ palliative interventions, post-WBRT survival is slightly better (7-8 months).…”