Toshiki Yoshimine

Computer-assisted Surgical Planning for Cerebrovascular Neurosurgery

OBJECTIVEnWe used three-dimensional reconstructed magnetic resonance images for planning the operations of 16 patients with various cerebrovascular diseases. We studied the cases of these patients to determine the advantages and current limitations of our computer-assisted surgical planning system as it applies to the treatment of vascular lesions.nnnMETHODSnMagnetic resonance angiograms or thin slice gradient echo magnetic resonance images were processed for three-dimensional reconstruction. The segmentation, based on the signal intensities and voxel connectivity, separated each anatomic structure of interest, such as the brain, vessels, and skin. A three-dimensional model was then reconstructed by surface rendering. This three-dimensional model could be colored, made translucent, and interactively rotated by a mouse-controlled cursor on a workstation display. In addition, a three-dimensional blood flow analysis was performed, if necessary. The three-dimensional model was used to assist in three stages of surgical planning, as follows: 1) to choose the best method of intervention, 2) to evaluate surgical risk, 3) to select a surgical approach, and 4) to localize lesions.nnnRESULTSnThe generation of three-dimensional models allows visualization of pathological anatomy and its relationship to adjacent normal structures, accurate lesion volume determination, and preoperative computer-assisted visualization of alternative surgical approaches.nnnCONCLUSIONnComputer-assisted surgical planning is useful for patients with cerebrovascular disease at various stages of treatment. Lesion identification, therapeutic and surgical option planning, and intraoperative localization are all enhanced with these techniques.

Spinal cystic schwannoma: A rare case report

A 78-year-old man was referred to our department with severe low back pain and gait disturbance. Lumbar magnetic resonance imaging (MRI) showed a large, well-circumscribed mass isointense with cerebrospinal fluid on T1- and T2-weighted imaging at the conus level. Arachnoid cyst without performing contrast-enhanced MRI was initially diagnosed. Intraoperative observation and postoperative histopathological examination revealed totally cystic schwannoma. Contrast-enhanced MRI is very important for the diagnosis of this rare tumor and should have been performed in this case. n n xa0 n n Key words: Totally cystic schwannoma, arachnoid cyst, magnetic resonance imaging.

Spontaneous spinal epidural hematoma: Magnetic resonance imaging for diagnosis and patient management in two cases

As far as operative indications for spinal epidural hematoma are concerned, symptoms and duration from onset are thought to be quite important. However, magnetic resonance imaging (MRI) intensity of the hematoma could be a key factor in determining the need for operative intervention. Here, we discuss two cases of spinal epidural hematoma. One was the operative case of a 71-year-old man who presented with left leg paresis. On the initial spinal MRI, a low-iso T1-weighted image (WI) showed a slight high-iso T2WI heterogenous intensity and a thick epidural mass that had compressed the spinal cord dorsolaterally from the C7 to T5 levels. The mass was diagnosed as a cervicothoracic epidural hematoma in the acute phase as coagulation seemed to be starting. Five hours after presentation, his symptoms evolved into complete paraplegia; therefore, decompression laminectomy and hematoma evacuation was performed. The other case was that of a 68-year-old woman with severe neck pain. The initial MRI demonstrated a T1WI iso, T2WI high homogenous intensity epidural mass from the C2 to T4 levels. A spinal epidural hematoma in the hyperacute phase was diagonesd. Conservative treatment was recommended, and her symptoms and hematoma almost disappeared within three days. When coagulation or organization of the hematoma has not started, its absorption might be expected at an early stage. MRI appearances, including hematoma intensity, combined with simultaneous clinical information might be very important for surgical decision making and predicting prognosis in cases of spinal epidural hematomas. n n xa0 n n Key words: Spinal epidural hematoma, MRI intensity, surgical decision making.