Application of MRS

The diagnosis of a tumor depends on accurate identification of the target area for biopsy. However, tumor heterogeneity and the inability of conventional structural data for identifying the most malignant areas can reduce this accuracy. To evaluate the feasibility and practicality of magnetic resonance spectroscopy (MRS)- and arterial spin labeling (ASL)-guided MRI navigation for needle biopsy of intracranial tumors. Thirty patients with intracranial tumors who underwent intraoperative stereotactic biopsy were retrospectively analyzed. Contrast-enhanced 3D-BRAVO or 3D-T2FLAIR structural data, combined with MRS and ASL data, were used to identify the target area for biopsy. High-choline or high-perfusion sites were chosen preferentially, and then the puncture trajectory was optimized to obtain specimens for histopathologic examination. Twenty-two specimens were collected from 20 glioma patients (two specimens each were collected from two patients) and ten specimens were collected from ten lymphoma patients. The diagnosis rate after the biopsy was 93.3% (28/30). Two gliomas were initially diagnosed as gliosis and subsequently diagnosed correctly after the collection of a second biopsy specimen. Combined MRS and ASL helped target selection in 23 cases (76.7%), including three cases each of low-enhancing and non-enhancing gliomas. In two cases, the target selection decision was changed because the areas initially chosen on the basis of positron emission tomography data did not match the high-perfusion areas identified with ASL. Compared with conventional MRI, combined MRS and ASL improved the accuracy of target selection for the stereotactic biopsy of intracranial tumors