CPT® Code 70558

Magnetic resonance (eg, proton) imaging, brain (including brain stem and skull base), during open intracranial procedure (eg, to assess for residual tumor or residual vascular malformation); with contrast material(s)

Magnetic resonance imaging (MRI) is a sophisticated imaging technique utilized to visualize the brain, including the brain stem and skull base, during open intracranial procedures. This procedure is particularly significant as it allows for real-time assessment of the brain's condition while surgery is ongoing. MRI operates on the principle of magnetic properties of hydrogen atoms present in the body, making it a noninvasive and non-radiating method of imaging. During the procedure, the patient is positioned on a motorized table that moves into a large MRI scanner, which contains a powerful magnet. This magnet generates a strong magnetic field that aligns the hydrogen atoms in the body. Subsequently, radiowaves are transmitted through this magnetic field, causing the protons in various tissues to emit specific radiofrequency signals. These signals are captured and processed by a computer, resulting in high-resolution, three-dimensional images of the brain. Intraoperative MRI is performed in specialized surgical suites equipped with MRI scanners, allowing neurosurgeons to obtain critical imaging data at any point during the surgery. This capability is essential for evaluating the extent of tumor removal, assessing residual vascular malformations, or assisting in the placement of deep brain neurostimulator systems. The integration of MRI into surgical procedures enhances the precision of the operation, minimizes the risk of damaging surrounding brain tissue, and ultimately contributes to improved surgical outcomes. The use of contrast material, such as gadolinium, further enhances the visibility of certain structures and abnormalities within the brain, providing the surgeon with vital information to ensure the success of the procedure. When MRI is performed without contrast, a different code is used, and specific coding guidelines apply when contrast is administered during the imaging process.