Introduction: Intra-axial brain lesions could be neoplastic or non-neoplastic. Some non-neoplastic brain lesions can mimic the neoplastic ones clinically, radiologically and sometimes histopathologically. This may lead to misdiagnosis and hence mismanagement. Magnetic Resonance Spectroscopy (MRS) is usually used as a complementary to conventional MRI to refine the diagnosis of intra-axial parenchymal brain lesions. MRS is based on the chemical shift properties of atoms in the brain tissue. Stereotactic-guided needle biopsy is a well-established method to obtain tissues for histopathological diagnosis of intra-axial brain lesions.
Methods: A prospective study conducted at the Department of neurosurgery, Alexandria University, Egypt, on 27 consecutive patients presenting with multifocal, diffuse, as well as deeply-seated intra-axial brain lesions. All patients had both brain MRI and MRS prior to stereotactic biopsy using Leksell Stereotactic System. Histopathological examinations of the obtained tissue specimens, using appropriate stains including immunostains, were performed.
Results: MRS diagnosed neoplastic brain lesions in 15 (56%) cases and non-neoplastic brain lesions in 12 (44%) cases. Correlation between the preoperative diagnosis by MRS and the histopathoplogical diagnosis following stereotactic biopsy of being either neoplastic or non-neoplastic lesion revealed matching in 25 out of 27 cases (sensitivity 88%, specificity 100%). Within the group of cases (n= 15) diagnosed preoperatively by MRS as being neoplastic, 12 cases were diagnosed having brain gliomas of different grades. The MRS grading of gliomas exactly matched the histopathological grading following stereotactic biopsy in 10 out of the 12 cases (sensitivity 89%, specificity 67%).
Conclusions: MRS may help with differential diagnosis, histologic grading, degree of infiltration, tumor recurrence, radionecrosis as well as differentiating between tumors and pseudotumors. MRS may be used intraoperatively to maximize tumor resection and to reduce the need for subsequent operations.
Patient Care: The present research may improve the patient care by providing a non-invasive diagnostic tool for his intra-axial brain lesion with high efficacy. Such diagnostic tool may save the patient the need for invasive brain biopsy surgery.
Learning Objectives: By the conclusion of this session, the participants should be able to: 1)Describe the importance of proper diagnosis of intra-axial brain lesions, 2)Discuss, in small groups the diagnostic value of MRS versus gold standard stereotactic biopsy in deeply-seated brain lesions, 3)Identify the sensitivity and specificity of using MRS as a diagnostic tool in intra-axial brain lesions