Intraoperative Magnetic Resonance Imaging Guidance Research Articles

Preclinical evaluation of an integrated robotic system for magnetic resonance imaging guided shoulder arthrography.

Shoulder arthrography is a diagnostic procedure which involves injecting a contrast agent into the joint space for enhanced visualization of anatomical structures. Typically, a contrast agent is injected under fluoroscopy or computed tomography (CT) guidance, resulting in exposure to ionizing radiation, which should be avoided especially in pediatric patients. The patient then waits for the next available magnetic resonance imaging (MRI) slot for obtaining high-resolution anatomical images for diagnosis, which can result in long procedure times. Performing the contrast agent injection under MRI guidance could overcome both these issues. However, it comes with the challenges of the MRI environment including high magnetic field strength, limited ergonomic patient access, and lack of real-time needle guidance. We present the development of an integrated robotic system to perform shoulder arthrography procedures under intraoperative MRI guidance, eliminating fluoroscopy/CT guidance and patient transportation from the fluoroscopy/CT room to the MRI suite. The average accuracy of the robotic manipulator in benchtop experiments is 0.90mm and 1.04deg, whereas the average accuracy of the integrated system in MRI phantom experiments is 1.92mm and 1.28deg at the needle tip. Based on the American Society for Testing and Materials (ASTM) tests performed, the system is classified as MR conditional.

A Frameless Stereotactic Implantation Technique for Depth Electrodes in Refractory Epilepsy Using Intraoperative Magnetic Resonance Imaging

Various complex techniques for depth electrode insertion in refractory epilepsy using preoperative imaging have been investigated. We evaluated a simple, accurate, cost-effective, and timesaving method using intraoperative magnetic resonance imaging (MRI). A neuronavigation-guided insertion tube attached to bone facilitated the placement of stereotactic percutaneous drill holes, bolt implantation, and frameless stereotactic insertion of depth electrodes. Image registration was carried out by head coil fiducials with trajectory planning and intraoperative electrode correction. In 6 patients with refractory epilepsy (3 women and 3 men; mean age, 30.0 years; range, 20-37 years), 58 depth electrodes (9-11 per patient) were placed. The mean length of the inserted electrodes was 37.3 mm ± 8.8 (mean ± SD) (range, 22.1-84.4 mm). The overall target point accuracy was 3.2 mm ± 2.2 (range, 0-8.6 mm), which was significantly different from the overall entry point accuracy of 1.4 mm ± 1.2 (P < 0.0001). All electrodes functioned perfectly, enabling high-quality stereo-electroencephalography recordings over a period of 7.3 days ± 0.5 (range, 7-8 days). The mean implantation time for 9-11 electrodes per patient was 115 minutes ± 36.3 (range, 75-160 minutes; 12 minutes for 1 electrode on average) including the intraoperative MRI (T1 three-dimensional magnetization-prepared rapid acquisition gradient echo, T2, and diffusion tensor imaging). There was no hemorrhage, infection, or neurologic deficit related to the procedure. Our frameless technique of depth electrode insertion using intraoperative MRI guidance is an accurate, reliable, cost-effective, and timesaving method for stereo-electroencephalography.

A Preliminary Experience with Use of Intraoperative Magnetic Resonance Imaging in Thalamic Glioma Surgery: A Case Series of 38 Patients

Thalamic gliomas are rare tumors that constitute 1%-5% of all central nervous system tumors. Despite advanced techniques and equipment, surgical resection remains challenging because of the vital structures adjacent to the tumor. Intraoperative magnetic resonance imaging (MRI) might play an active role during brain tumor surgery because it compensates for brain shift or operation-induced hemorrhage, which are challenging issues for neurosurgeons. We reviewed 38 patients treated surgically under intraoperative MRI guidance between January 2008 and July 2015 at our center. Preoperative, intraoperative, and postoperative MRI scans were reviewed. Preoperative and postoperative motor power, morbidity and mortality, resection rate, surgical approach, pathologic results, and patient demographics were also reviewed. Mean patient age was 37 years ± 18; 12 patients were included in the low-grade group, and 26 patients were included in the high-grade group. Under intraoperative MRI guidance, the gross total resection rate was increased from 16 (42.1%) to 26 (68.4%), and the near-total or subtotal resection rate was increased from 5 (13.2%) to 9 (23.7%). Hematoma formation was discovered in 3 patients on intraoperative MRI scan; each patient underwent a hemostatic operation immediately. With improvements in neurosurgical techniques and equipment, surgical resection is considered feasible in patients with thalamic gliomas. Intraoperative MRI may be helpful in achieving the maximal resection rate with minimal surgical-related morbidity. However, because of severe disease progression, the overall prognosis is unfavorable.

Closed-loop asymmetric-tip needle steering under continuous intraoperative MRI guidance.

Magnetic resonance imaging (MRI) provides excellent image contrast for various types of tissues, making it a suitable choice over other imaging modalities for various image-guided needle interventions. Furthermore, robot-assistance is maturing for surgical procedures such as percutaneous prostate and brain interventions. Although MRI-guided, robot-assisted needle interventions are approaching clinical usage, they are still typically open-loop in nature due to the lack of continuous intraoperative needle tracking. Closed-loop needle-based procedures can improve the accuracy of needle tip placement by correcting the needle trajectory during insertion. This paper proposes a system for robot-assisted, flexible asymmetric-tipped needle interventions under continuous intraoperative MRI guidance. A flexible needle's insertion depth and rotation angle are manipulated by an MRI-compatible robot in the bore of the MRI scanner during continuous multi-planar image acquisition to reach a desired target location. Experiments are performed on gelatin phantoms to assess the accuracy of needle placement into the target location. The system was able to successfully utilize live MR imaging to guide the path of the needle, and results show an average total targeting error of 2.5±0.47mm, with an average in-plane error of 2.09±0.33mm.

Successful Deep Brain Stimulation Surgery With Intraoperative Magnetic Resonance Imaging on a Difficult Neuroacanthocytosis Case

Chorea acanthocytosis is a progressive hereditary neurodegenerative disorder characterized by hyperkinetic movements, seizures, and acanthocytosis in the absence of any lipid abnormality. Medical treatment is typically limited and disappointing. We report on a 32-year-old patient with chorea acanthocytosis with a failed attempt at awake deep brain stimulation (DBS) surgery due to intraoperative seizures and postoperative intracranial hematoma. He then underwent a second DBS operation, but under general anesthesia and with intraoperative magnetic resonance imaging guidance. Marked improvement in his dystonia, chorea, and overall quality of life was noted 2 and 8 months postoperatively. DBS surgery of the bilateral globus pallidus pars interna may be useful in controlling the hyperkinetic movements in neuroacanthocytosis. Because of the high propensity for seizures in this disorder, DBS performed under general anesthesia, with intraoperative magnetic resonance imaging guidance, may allow successful implantation while maintaining accurate target localization.

Deep brain stimulation for movement disorders: Patient selection and technical options

Deep brain stimulation (DBS) is used as a treatment for movement disorders. Unlike ablative procedures, DBS is reversible and adjustable. It is approved in the United States for treatment of Parkinson disease (PD), dystonia, and tremor. This surgical procedure is considered safe and effective for the management of the motor symptoms of these disorders, although it does not cure the underlying conditions. Potential complications of DBS surgery include intracranial hemorrhage, infections, and complications related to the hardware. There may also be complications related to stimulation or programming, although these are usually associated with dosages of dopaminergic medications and are reversible. DBS is usually performed under conscious sedation with awake evaluation during intraoperative physiologic testing. Typically, the procedure is performed with stereotactic image guidance, using computed tomography or magnetic resonance imaging (MRI) for targeting. Surgery can be accomplished with stereotactic frames or frameless systems. Recently, intraoperative MRI guidance has become available and is an alternative to the traditional surgical procedure, allowing for implantation of the DBS device under general anesthesia.

Magnetic Resonance Imaging-Guided Focused Laser Interstitial Thermal Therapy for Subinsular Metastatic Adenocarcinoma

To describe the novel use of the AutoLITT System (Monteris Medical, Winnipeg, Manitoba, Canada) for focused laser interstitial thermal therapy (LITT) with intraoperative magnetic resonance imaging (MRI) and stereotactic image guidance for the treatment of metastatic adenocarcinoma in the left insula. The patient was a 61-year-old right-handed man with a history of metastatic adenocarcinoma of the colon. He had previously undergone resection of multiple lesions, Gamma Knife radiosurgery, and whole-brain radiation. Despite treatment of a left insular tumor, serial imaging revealed that the lesion continued to enlarge. Given the refractory nature of this tumor to radiation and the deep-seated location, the patient elected to undergo LITT treatment. The center of the lesion and entry point on the scalp were identified with STEALTH (Medtronic, Memphis, Tennessee) image-guided navigation. The AXiiiS Stereotactic Miniframe (Monteris Medical) for the LITT system was secured onto the skull, and a trajectory was defined to achieve access to the centroid of the tumor. After a burr hole was made, a gadolinium template probe was inserted into the AXiiiS base. The trajectory was confirmed via an intraoperative MRI, and the LITT probe driver was attached to the base and CO2-cooled, side-firing laser LITT probe. The laser was activated and thermometry images were obtained. Two trajectories, posteromedial and anterolateral, produced satisfactory tumor ablation. LITT with intraoperative MRI and stereotactic image guidance is a newly available, minimally invasive, and therapeutically viable technique for the treatment of deep seated brain tumors.

Supratentorial Low-Grade Glioma Resectability: Statistical Predictive Analysis Based on Anatomic MR Features and Tumor Characteristics

To retrospectively assess the main variables that affect the complete magnetic resonance (MR) imaging-guided resection of supratentorial low-grade gliomas. Institutional review board approval was obtained for this retrospective HIPAA-compliant study, with the requirement for informed consent waived. Data from 101 patients (61 men, 40 women; mean age, 39 years; age range, 18-72 years) who had nonenhancing supratentorial mass lesions that were histopathologically diagnosed as low-grade (World Health Organization grade II) gliomas and consecutively underwent surgery with intraoperative MR imaging guidance were analyzed. There were 21 low-grade astrocytomas, 64 oligodendrogliomas, and 16 mixed oligoastrocytomas. Initial and residual tumor volumes were measured on intraoperative T2-weighted MR images and three-dimensional spoiled gradient-echo MR images. The anatomic relationships between the tumor and eloquent cortical and/or subcortical regions and the influence of these relationships on the extent of resection were analyzed on the basis of preoperative MR imaging findings. Summary measures, univariate Fisher exact test and t test, and multivariate logistic regression analyses were performed. Tumor volume ranged from 2.7-231.0 mL. Univariate analyses revealed the following tumor characteristics to be significant predictive variables of incomplete tumor resection: diffuse tumor margin on T2-weighted MR images, oligodendroglioma or oligoastrocytoma histopathologic type, and large tumor volume (P < .05 for all). Tumor involvement of the following structures was associated with incomplete resection: corpus callosum, corticospinal tract, insular lobe, middle cerebral artery, motor cortex, optic radiation, visual cortex, and basal ganglia (P < .05 for all). Multivariate analyses revealed that incomplete tumor resection was due to tumor involvement of the corticospinal tract (P < .01), large tumor volume (P < .01), and oligodendroglioma histopathologic type (P = .02). The main variables associated with incomplete tumor resection in 101 patients were identified by using statistical predictive analyses.

Remotely-Controlled Approach for Stereotactic Neurobiopsy

The objective of this study was to develop, demonstrate, and validate a remotely controlled operation scheme coupled with prospective magnetic resonance imaging (MRI)-based stereotaxy for in vivo neurosurgical applications. The novel concept of the prospective guidance scheme is to employ tomographical imaging feedback, such as MRI or CT, to facilitate prospectively the targeting process of a biopsy needle at near-real-time speed (1 image/s). Because the orientation of a biopsy needle pivoted at an entry point on die patient's skull has 2 degrees of freedom, the alignment of its trajectory to a target point can be guided by two-dimensional (2D) images whose plane is placed perpendicular to the desired trajectory. Using near-real-time 2D visual feedback during the adjustment of the alignment guide, the required trajectory alignment can be translated into a simple targeting task on a computer monitor employing a suitable graphic presentation. Also, both adjustments for the alignment and introduction of the biopsy needle were accomplished remotely with image-based feedback. The use of the method in actual MR-guided brain lesion biopsy procedures at 1.5 T showed an improved tissue yield due to the improved targeting accuracy even in the presence of brain shift. Furthermore, the postalignment trajectory can be validated immediately using near-real-time MRI scans in two orthogonal views before needle insertion. Because the final needle position is always visualized and confirmed, the consequent tissue sampling is performed with greater certainty, even in the case of a negative diagnosis. The actual targeting error was 1.53 ± 0.17 mm from an intended target location, with the maximum distance error of 1.72 mm at a depth of 85 mm. This remotely controlled surgical approach with intraoperative MRI guidance is feasible at 1.5 T, and has allowed neurosurgeons to perform neurobiopsies comfortably and efficiently in a routine clinical MR scanner. This scheme provides a unique alternative stereotactic procedure that can take full advantage of the prospective guidance potential offered by various modern tomographic imaging systems.

Interactive magnetic resonance imaging-guided management of intracranial cystic lesions by using an open magnetic resonance imaging system.

The authors present their experience with neurosurgical procedures requiring real-time imaging feedback such as aspiration of a cystic structure or abscess cavity, decompression of hydrocephalic ventricles, management of arachnoid cysts, and installation of permanent or temporary drainage conduits, in which interactive magnetic resonance (MR) imaging guidance was used to monitor structural alterations associated with the procedure. Drainage of eight intraparenchymal brain abscesses in seven patients, decompression of space-occupying cystic or necrotic brain tumors in four patients, and endoscopic management of hydrocephalus associated with arachnoid cysts in three patients were performed using MR imaging-guided frameless stereotaxy in an open-configuration 0.5-tesla superconducting MR imaging system. Intraoperative MR imaging guidance provided accurate information on the course of the surgical procedure and associated intraoperative changes in tissue position, such as the degree of cyst aspiration, the presence or absence of hemorrhage or induced swelling, and changes associated with decompression of adjacent brain parenchyma and the ventricular system. No clinically significant complications were encountered in any patient. There were no targeting errors, and procedural objectives were accomplished in all cases. Drainage of brain abscesses, punctures of cystic or necrotic intracranial lesions with subsequent aspiration, and management of hydrocephalus can be performed safely and accurately by monitoring the procedure using real-time MR imaging to obtain immediate feedback on associated dynamic tissue changes.

Intraoperative Magnetic Resonance Imaging Guidance for Intracranial Neurosurgical Procedures

A 0.5 Tesla open configuration magnetic resonance imaging (MRI) system (SignaSP [GE Medical Systems; Milwaukee, WI]) is sited in an operating room environment at Brigham and Women's Hospital for MRI-guided surgical and interventional procedures. The vertical gap provides patient access to two surgeons or interventionalists, whereas open flexible transmit-receive coils allow exposure of the surgical field. A major application of this system at Brigham and Women's Hospital is intraoperative MRI guidance for intracranial biopsies and open craniotomies. During the past 2œ years, more than 200 intracranial procedures have been performed using intraoperative MRI guidance. For intracranial biopsies, MRI guidance provides several advantages, including high sensitivity for lesion localization; interactive navigation, eliminating the need for a stereotactic frame; multiplanar image confirmation of biopsy site location; and early detection of complications. Based on our experience with open craniotomies, we think that image guidance significantly improves the ability of the neurosurgeon to resect abnormal tissue selectively while preserving adjacent eloquent areas. Furthermore, our experience indicates that intraoperative imaging offers advantages over conventional stereotactic image guidance, including the ability to compensate for shifts in brain position during surgery, and allows for early identification of complications. Intraoperative MRI-guided neurosurgery is a multidisciplinary effort involving the neurosurgeon, neuroradiologist, technologist, nursing staff, and engineers. In our experience, there is little doubt that MRI guidance improves the technical aspects of the neurosurgical procedures; however, the impact of this technology on clinical outcomes and cost effectiveness await further study.

Surgical treatment of low-grade gliomas in the intraoperative magnetic resonance imager

Radical resection of low-grade gliomas can decrease the incidence of recurrence, the time to tumor progression, and the incidence of malignant transformation. The authors present a series of 25 patients who underwent craniotomy and resection of low-grade tumor in an intraoperative magnetic resonance (MR) imager. This is an open configuration 0.5-tesla imager developed by The Brigham and Women's Hospital and General Electric, in which a patient can be placed to undergo surgery. Gross-total removal was accomplished under real-time image guidance. These intraoperative images allow definitive localization and targeting of the lesions and accommodate anatomical changes that may occur during surgery. The authors consistently found that the extent of abnormality seen on the intraoperatively obtained films of resection was larger than that apparent in the surgical field of view alone. Intraoperative imaging made accurate surgical identification of these abnormal areas and subsequent resection possible. Patients with tumors adjacent to or within motor or language cortex underwent resection while awake, with monitoring of neurological function. In these cases, an aggressive resection without increased neurological morbidity was accomplished using the image guidance in conjunction with serial testing. A 1-month postoperative MR image was obtained in all patients. These correlated with the final intraoperative images obtained after the resection was completed. Only one patient had a mild postoperative deficit that remained at the 1-month follow-up examination. As the long-term outcome in patients with low-grade gliomas has been shown to correspond to the degree of resection, surgical resection in which intraoperative MR imaging guidance is used can be an invaluable modality in the treatment of these tumors.