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Interventional MRI has clearly grown from primarily a preclinical field, into an image guidance modality for safe, effective, and personalized patient care. The chapter provides an overview on why interventional MRI is a unique tool to guide and monitor tumor ablations, biopsies, endovascular interventions or neurosurgical interventions, and what is needed to make it a clinical reality beyond specialized centers.

Gliomas are central nervous system neoplasms that infiltrate the surrounding brain parenchyma, complicating their treatment. Tools that increase extent of resection (EOR) while preventing neurological deficit are vital for improving outcomes for patients diagnosed with gliomas. Intraoperative MRI (iMRI) can be used in the surgical resection of gliomas and has demonstrated great potential for maximizing extent of resection for both high and low grade gliomas in an attempt to improve patient outcomes. iMRI is a promising adjunct for the neurosurgical operating theater that is safe and effective in increasing EOR. However, it has limitations such as cost and need for specialized equipment. Although the majority of evidence is encouraging, it is primarily derived from retrospective studies, thus emphasizing the need for randomized trials more evident and necessary. Here, we review the current evidence supporting the use of iMRI for the resection of gliomas, the potential advantages, and limitations of this imaging technique in the operating room.

Oligodendrogliomas and anaplastic oligodendrogliomas are a well-defined class of infiltrating primary brain tumors characterized by 1p/19q chromosomal co-deletion and isocitrate dehydrogenase (IDH) mutation. These tumors are treated with gross total surgical resection, when possible, followed by adjuvant chemotherapy and radiation. The use of multiple intraoperative tools such as intraoperative magnetic resonance imaging (iMRI), neuronavigation, neurophysiological monitoring, awake craniotomy, ultrasound, and tumor chemiluminescence helps to maximize the extent of resection while minimizing deficits. Herein, we describe the role of these techniques and their limitations for the resection of oligodendroglial tumors.

State-of-the-art magnetic resonance angiography with high-field magnetic resonance imaging (MRI) scanners can be used as a reliable alternative to multislice computed tomography angiography and invasive digital angiography for the assessment of the thoracic and abdominal aorta, both in the diagnosis and posttreatment evaluation. Advances in MRI have led to its current role as an alternative and robust diagnostic modality of choice for the assessment of the whole spectrum of aortic disorders.

Magnetic resonance is a powerful phenomenon that has offered the medical field an imaging technique, magnetic resonance imaging (MRI) that has revolutionized medicine for the past 3 decades. The magnetic field of MRI scanners plays a central role in the quality of images and as such there has been a relentless drive toward higher magnetic fields. The higher fields, however, present formidable challenges such as high magnetic susceptibility, radio frequency inhomogeneities, and patient safety. As of this writing, the magnetic field strength of the majority of clinical scanners is 1.5 T. Today, 3-T whole-body scanners are appearing in hospitals at a rapid rate, and more than 20 academic institutions and research laboratories around the world operate 7-T whole-body scanners. This has changed the classification of MRI scanners as low field, high field, or ultrahigh field. This chapter reviews the theory and physics of ultrahigh field MRI scanning.

The targeting and implantation of deep brain stimulation (DBS) electrodes traditionally is based on the interpretation of preoperative MRI, with most centers employing intraoperative electrophysiological recordings to verify actual lead location. Recent advances in real-time MRI guidance, however, are changing this paradigm. This chapter addresses advances in image guidance for functional neurosurgery in three important areas: (1) optimization of preoperative techniques for visualizing the target structure and related tractography to optimize target selection in DBS, (2) development of interventional-MRI (iMRI) for real-time visualization of DBS electrode placement in MRI-visible anatomic targets, and (3) the development of iMRI gene therapy delivery strategies for the treatment of Parkinson’s disease.

Noninvasive imaging studies involving small animals are becoming increasingly important in preclinical pharmacological, genetic, and biomedical cardiovascular research. Especially small animal magnetic resonance imaging (MRI) using high field and clinical MRI systems has gained significant importance in recent years. Compared to other imaging modalities, like computer tomography, MRI can provide an excellent soft tissue contrast, which enables the characterization of different kinds of tissues without the use of contrast agents. In addition, imaging can be performed with high spatial and temporal resolution. Small animal MRI cannot only provide anatomical information about the beating murine heart; it can also provide functional and molecular information, which makes it a unique imaging modality. Compared to clinical MRI examinations in humans, small animal MRI is associated with additional challenges. These included a smaller size of all cardiovascular structures and a up to ten times higher heart rate. Dedicated small animal monitoring devices make a reliable cardiac triggering and respiratory gating feasible. MRI in combination with molecular probes enables the noninvasive imaging of biological processes at a molecular level. Different kinds of iron oxide or gadolinium-based contrast agents can be used for this purpose. Compared to other molecular imaging modalities, like single photon emission computed tomography (SPECT) and positron emission tomography (PET), MRI can also provide imaging with high spatial resolution, which is of high importance for the assessment of the cardiovascular system. The sensitivity for detection of MRI contrast agents is however lower compared to sensitivity of radiation associated techniques like PET and SPECT. This chapter is divided into the following sections: (1) "Introduction," (2) "Principals of Magnetic Resonance Imaging," (3) "MRI Systems for Preclinical Imaging and Experimental Setup," and (4) "Cardiovascular Magnetic Resonance Imaging."

Publisher Summary This chapter describes a method for combining endonasal endoscopy with intraoperative magnetic resonance (IMRI) in the removal of pituitary tumors. Patients are intubated and positioned supine on the operating table, and a Foley catheter is placed. Antibiotics, glucocorticoids, and antihistamines are administered. MRI-compatible EKG leads are placed and attached to an MRI-compatible anesthesia machine. The nasal mucosa is vasoconstricted topically with cottonoids soaked in 4 ml of 4% cocaine. A 0°, 30-cm, rigid 4-mm endoscope is introduced through the left nostril and held in place with a flexible scope holder. The right nostril is used for introduction of surgical instruments. When IMRI is implemented, a radiofrequency-shielded operating room must be used along with dedicated anesthesia equipment, including ventilator, infusion pumps, and monitoring screens. Pressure transducers must be kept outside the scanner to prevent artifacts. Daily quality assurance and shimming are performed on the magnet. All electronic equipment is unplugged during quality assurance and image acquisition. The magnet and patient reference frames must be placed in the line of sight of the infrared camera. Pre-resection images of the sella, parasellar structures, and nasopharynx are obtained before and after administration of intravenous contrast (gadolinium, 0.6 ml/kg) and are subsequently used for stereotactic navigation. During the surgical procedure, the magnet is lowered under the bed. It is raised after the resection is complete, all electronic equipment is unplugged, and images are obtained with and without intravenous contrast. Post-resection images are compared to pre-resection images. If residual tumor is noted on the post-resection scans, reexploration with the endoscope is performed to visualize and resect tumor remnants, using stereotactic navigation for localization.

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This chapter discusses clinical brain imaging and provides an overview of computerized axial tomography and magnetic resonance imaging. The introduction of computerized axial tomography (CAT or CT) and magnetic resonance imaging (MRI or MR) into the field of brain imaging has resulted in dramatic improvements in the evaluation of suspected intracranial abnormalities. The chapter provides an overview of these two techniques. Magnetic resonance imaging (MRI) represents a recent and dramatic advance in neurodiagnostic imaging. This noninvasive anatomic/pathologic imaging technique utilizes magnetic fields and radiofrequency (RF) energy to manipulate atomic nuclei. The essential components of a CT scanner include the gantry, x-ray source, detection system, computer, and display network. Although MRI represents one of the most sophisticated and detailed central nervous system evaluations possible, there are limitations to this technique. A wide variety of artifacts exist, with the most common being patient motion. X-ray computed tomography (CT), positron emission tomography (PET), single photon emission computed tomography (SPECT), and nuclear magnetic resonance imaging (MRI) all fall in the general imaging class of reconstruction of the object from their projections. Tomography refers to the creation of images in slices or sections.