Intraoperative MRI Enables More Complete Resection of Pediatric Brain Tumors

By Violette Recinos, MD

Pediatric brain tumors are a heterogeneous group of tumors with varying outcomes, prognoses and treatments. Surgery is often the first step in management, with the main goals being tissue diagnosis and, when possible, tumor resection. In many cases, a gross total resection can improve long-term progression-free survival and, in some instances, even be curative.

Certain tumors, such as gliomas, can pose various surgical challenges secondary to location and the extent of infiltration of normal brain tissue. The development of stereotactic navigation systems has made tumor localization and resection a very precise and calculated process. Despite this precision, confirming the extent of surgical resection via navigation is limited by intraoperative brain shifts and surgical manipulation. For tumors with ill-defined infiltrating borders, surgeons often must rely on their visualization, tactile sensation and experience to determine the boundaries of the resection cavity.

A ‘second look’ to confirm resection goals

With the advent of the intraoperative MRI suite (IMRIS Neuro™ intraoperative suite) at Cleveland Clinic, we now have an extra tool to help achieve our surgical goals. The ability to obtain a high-quality scan to evaluate the surgical bed prior to closing allows the surgeon to go back and take a “second look” to confirm that surgical resection goals have been met and provide reassurance for both the physician and the family.

This extra step in the surgical suite has the potential to spare a child an additional operation to remove a small residual tumor (Figure). A better resection may also delay or obviate the need for radiation treatment, an adjuvant therapy with significant potential side effects and developmental consequences.

Figure. Series of MRIs in a recent pediatric patient demonstrating the utility of intraoperative imaging.
Left: Preoperative image showing a cystic mass in the fourth ventricle with enhancing portion in the superior vermis (arrow). Middle: Intraoperative image showing residual tumor in the superior vermis (arrow) after cyst resection, prompting additional operative work to remove the residual tumor. Right: Postoperative image showing complete resection of the tumor (arrow).

Furthermore, because many children need sedation when undergoing MRI, the intraoperative MRI suite has been especially useful in allowing these patients to undergo pre-,intra- and postoperative imaging with a single administration of anesthesia.

Broadly applicable

The intraoperative MRI suite is useful for both benign and malignant tumors. For low-grade processes such as pilocytic astrocytoma, a gross total resection, when possible, can result in a long-term cure. Even for higher-grade tumors such as medulloblastoma, more extensive tumor resection has been associated with better prognosis. Patients with less than 1.5 cm3 of disease may be stratified as average risk and thus may require less adjuvant therapy than those considered high risk because of greater tumor burden.

Our intraoperative MRI suite is also helpful in evaluating for potential complications early on. If there is concern about possible infarct or hemorrhage, an intraoperative scan can help minimize the delay involved in routine closing and transport, allowing for faster action.

On the horizon: LITT in the intraoperative MRI suite

Looking ahead, Gene Barnett, MD, Director of Cleveland Clinic’s Rose Ella Burkhardt Brain Tumor and Neuro-Oncology Center, is using laser-induced interstitial thermotherapy (LITT) in adults to treat deep-seated tumors in difficult-to-access locations that were once deemed inoperable. This surgery is performed in the intraoperative MRI suite to allow for laser placement and real-time monitoring by MRI. Advances in this technology are evolving and will certainly have implications in the pediatric population as well.

Because of the many advantages the intraoperative MRI suite offers, its use is quickly becoming a standard practice for our pediatric patients. Longitudinal outcome studies may well show this to be a superior approach in the formidable task of treating pediatric patients with brain tumors.

Dr. Recinos is Section Head of Pediatric Neurosurgical Oncology and a staff member in the Section of Pediatric and Congenital Neurosurgery and the Rose Ella Burkhardt Brain Tumor and Neuro-Oncology Center. Her specialty interests include brain and spinal cord tumors as well as general pediatric neurosurgery. She can be reached at 216.444.4549 or recinov@ccf.org.