Objective We describe the development and implementation of a new open configuration magnetic resonance imaging (MRI) system, with which neurosurgical procedures can be performed using image guidance. Our initial neurosurgical experience consists of 140 cases, including 63 stereotactic biopsies, 16 cyst drainages, 55 craniotomies, 3 thermal ablations, and 3 laminectomies. The surgical advantages derived from this new modality are presented. Methods The 0.5-T intraoperative MRI system (SIGNA SP, Boston, MA), developed by General Electric Medical Systems in collaboration with the Brigham and Women's Hospital, has a vertical gap within its magnet, providing the physical space for surgery. Images are viewed on monitors located within this gap and can also be acquired in conjunction with optical tracking of surgical instruments, establishing accurate intraoperative correlations between instrument position and anatomic structures. Results A wide range of standard neurosurgical procedures can be performed using intraoperative MRI. The images obtained are clear and provide accurate and immediate information to use in the planning and assessment of the progress of the surgery. Conclusion Intraoperative MRI allows lesions to be precisely localized and targeted, and the progress of a procedure can be immediately evaluated. The constantly updated images help to eliminate errors that can arise during frame-based and frameless stereotactic surgery when anatomic structures alter their position because of shifting or displacement of brain parenchyma but are correlated with images obtained preoperatively. Intraoperative MRI is particularly helpful in determining tumor margins, optimizing surgical approaches, achieving complete resection of intracerebral lesions, and monitoring potential intraoperative complications.

Development and implementation of intraoperative magnetic resonance imaging and its neurosurgical applications.

The aim of this retrospective study was to assess the contribution of thallium-201 single-photon emission tomography (SPET) in the detection and differential diagnosis of brain tumours. In 90 patients 201Tl SPET was performed because of clinical or radiological suspicion of tumoral invasion, completed by technetium-99m hexamethylpropylene amine oxime and 99mTc-sestamibi SPET in some patients. For all tumours, diagnosis was based on biopsy or autopsy. Other diagnoses were made only after clinical and radiological follow-up for at least 6 months. Histologically tumours consisted of astrocytoma stage I or II (number of patients, n=6), astrocytoma stage III (n=8), glioblastoma multiforme (n=14) and oligodendroglioma (n=3), brain metastasis (n=14), lymphoma (n=3), meningioma (n=3), pituitary adenoma (n=2), pineal tumour (n=1), colloid cyst (n=1) and craniopharyngioma (n=1). False-negative studies included pineal tumour (n=1), colloid cyst (n=1), craniopharyngioma (n=1), astrocytomas stage I or II (n=6) and stage III (n=3), oligodendroglioma (n=2) and metastasis in the brain stem (n=1). Additional metastases approximately < 1.5 cm were not detected in two patients and 201Tl SPET underestimated tumoral extent in one patient suffering from glioblastoma multiforme (n=1). A false-positive study was obtained in a patient with skull metastasis (n=l). All 15 patients who were finally shown to suffer from ischaemic infarction had a normal SPET study 9–28 days after the onset of symptomatology. Of five patients with haemorrhagic infarction, studied within 2 weeks, four were false-positive. Of six patients with intracranial haemorrhage, studied 9–39 days later, one showed focal 201Tl accumulation. Two further false-positive studies consisted of angioma and epidural haematoma. Finally, SPET studies were normal in six patients with definite diagnosis of (reactive) gliosis (n=3), Binswanger's encephalopathy (n=1), postinfectious encephalopathy (n=1) and multiple sclerosis (n=1). In the patient population presented, sensitivity of 201Tl SPET for supratentorial brain tumours was 71.7% and specificity was 80.9%. Clinical information and control SPET studies in combination with early, 30-min and 3- to 4-h delayed imaging may be expected to improve on these figures. On the other hand it seems that, in addition to tumoral histology, the presence of tumours in the fossa posterior and small volumes contribute to the occurrence of falsenegative 201Tl SPET studies.

Sensitivity and specificity of thallium-201 single-photon emission tomography in the functional detection and differential diagnosis of brain tumours.

Object. The study was conducted to determine the association between dual-isotope single-photon emission computerized tomography (SPECT) scanning and histopathological findings of tumor recurrence and survival in patients treated with high-dose radiotherapy for glioblastoma multiforme. Methods. Studies in which SPECT with 201Tl and 99mTc-hexamethypropyleneamine oxime (HMPAO) were used were performed 1 day before reoperation in 47 patients with glioblastoma multiforme who had previously been treated by surgery and high-dose radiotherapy. Maximum uptake of 201Tl in the lesion was expressed as a ratio to that in the contralateral scalp, and uptake of 99mTc-HMPAO was expressed as a ratio to that in the cerebellar cortex. Patients were stratified into groups based on the maximum radioisotope uptake values in their tumor beds. The significance of differences in patient gender, histological characteristics of tissue at reoperation, and SPECT uptake group with respect to 1-year survival was elucidated by using th...

Dual-isotope single-photon emission computerized tomography scanning in patients with glioblastoma multiforme: association with patient survival and histopathological characteristics of tumor after high-dose radiotherapy.

Thallium-201 for oncological imaging in children

Purpose: The follow-up of patients with malignant brain tumors after surgery, radiation, and/or chemotherapy has been inadequate for evaluating brain tumor burden using computerized tomography (CT) or magnetic resonance imaging (MRI) Thallium-201 has been shown to concentrate in viable tumor, and TI-201 single photon emission computerized tomography (SPECT) imaging can identify tumor burden more accurately than CT Methods and Materials: Thirty-one patients with glioblastoma and three patients with low grade astrocytoma were studied with TI-201 SPECT Histologic diagnosis was obtained in all patients by biopsy and all patients had CT scans within 2 weeks of the SPECT study Seventeen patients were followed with one or more SPECT and CT evaluations Results: Single photon emission computerized tomography studies, after surgery, radiotherapy, and/or chemotherapy, were more accurate than CT in identifying progression or regression of disease Twenty-three patients had evidence of disease and 11 patients had no evidence of recurrent disease in the initial TI-201 SPECT study following therapy Computerized tomography identified 20 of the 23 patients with disease and 6 of 11 patients with no recurrent disease Follow-up with TI-201 SPECT in 17 patients suggested progression of disease in 9 patients, while CT showed progression in only 3 patients Clinical examinations and repeat CT studies confirmed the accuracy of TI-201 SPECT images Conclusion: We found TI-201 SPECT more accurate than CT scans in a prospective evaluation of 34 patients with brain tumor Follow-up studies with both TI-201 SPECT and CT imaging in 17 patients demonstrated that sPECT was more reliable than CT in identifying progression, improvement, or no change in brain tumor burden

A prospective evaluation of thallium-201 single photon emission computerized tomography for brain tumor burden

Dual isotope brain SPECT was performed in a patient with recurrent brain tumor (grade II astrocytoma). In this case, a good coregistration of brain perfusion and tumor images was obtained because Tc-99m HMPAO and the Tl-201 chloride imaging were done simultaneously using a Triad SPECT unit. This method might play an important clinical role in the evaluation of patients with recurrent brain tumors.

Haghbin M

Papers

Dual isotope SPECT in the evaluation of recurrent brain tumor.