Low-grade gliomas often occur in young adults, with an average age of 40 years. The presence of epilepsy and long-term symptoms prior to definitive diagnosis is typical. However, patients may also present with symptoms of occupancy effects, such as focal symptoms like headache, limb weakness, behavioral and personality changes, visual function deficits, and speech impairment. Although signs and symptoms due to cranial hypertension and occupancy effects can occur suddenly, they are uncommon. Hairy cell astrocytomas growing in the cerebral or cerebellar hemispheres are typically characterized by enhancing nodules and cystic cavities connected to the tumor on imaging. These tumors can also be located in the optic pathway or the midbrain periaqueduct, but cystic changes are uncommon. Diffuse low-grade astrocytomas are usually located in the supratentorial frontal region and appear on computed tomography (CT) as isointense or hypointense occupying lesions with slight or no enhancement. On magnetic resonance imaging (MRI), however, they appear as hyposignal with no enhancement in the T1-weighted phase and high signal in the T2-weighted phase. Oligodendrogliomas show calcifications on CT, and their MRI appearance is similar to that of other low-grade gliomas, and like diffuse low-grade astrocytomas, the tumors are usually non-enhancing. Although a diagnosis of low-grade glioma with biopsy or resection based on “typical” MRI or CT findings generally leads to consistent pathologic findings, there are limitations in the accuracy of grading tumors based on MRI or CT findings alone. Barker et al. performed biopsies of patients with typical low-grade gliomas on MRI and found that the incidence of high-grade gliomas tended to increase with increasing patient age. Other studies have also concluded that conventional imaging has limitations in correctly determining the histologic changes in low-grade gliomas. Although most non-hairy cell low-grade gliomas do not show enhancement on CT or MRI, nearly one-third of tumors may show some degree of enhancement. This enhancement is usually in the form of small patches. If there is significant enhancement on CT or MRI, especially with necrosis in the central region, it is generally suggestive of a progressive tumor. In some, but not all, patients with a pathologic diagnosis of low-grade glioma, contrast enhancement is considered a poor prognostic factor, and Daumas-Duport et al. suggested that imaging enhancement should be considered as a gross manifestation of microvascular proliferation and that the tumor should be malignant. Patients with low-grade oligodendroglioma with a clear diagnosis may develop malignancy during follow-up and monitoring, showing clinical signs of deterioration and accelerated tumor growth on imaging. If new foci of enhancement appear in low-grade gliomas that have not previously shown enhancement, special attention should be paid to tumor malignancy. Pirzkall et al. used three-dimensional magnetic resonance spectroscopy (MRS) to image metabolic tumor changes in 20 patients with low-grade gliomas and used the choline/N-formyl-aspartate index (CNI) to delineate the boundaries of metabolically active tumors. . There was a correlation between the tumor bioactive volume determined by applying this method and the tumor anatomical volume (volume determined by T2-weighted phase), and the CNI (classified as small, medium, or large) was very similar in astrocytomas, oligodendrogliomas, and mixed gliomas in all patients. Overall, the tumor bioactive volume closely matched the anatomical volume of the tumor, as they were consistent in 55% of patients, and in the other 45% of patients, a small portion of the bioactive volume (mean 2.3 mL) exceeded the anatomical volume of the tumor (maximum range 13 mm), and this excess volume was associated with the volume of tumor spread along the conduction tract and corpus callosum. Therefore, the authors propose that the tumor bioactive volume based on CNI determination can help to determine the extent of tumor for stereotactic biopsy and surgical resection. It has even been suggested that the tumor boundary determined by MRS includes exactly the invasive part of the tumor, so that high-dose radiation therapy can be administered to this part of the tumor using either the aptamer technique or the intensity-modulated technique.Croteau et al. found that MRS was superior to conventional MRI in terms of accuracy in determining the tumor boundary and the extent of invasion by correlating tumor MRS changes with stereotactic biopsy. Fuss et al. applied dynamic enhancement MRI to study the relationship between prognosis and tumor angiogenesis in low-grade gliomas. found that early recurrence could occur in the hyperemic fraction of the tumor after radiotherapy and that a decrease in blood volume in both normal brain and tumor could occur 6-12 months after >40 Gy radiotherapy (mean decrease of 30%). Since these changes can also be measured in non-enhanced tumors, suggesting that the application of dynamic enhancement MRI can help detect those tumors with increased angiogenesis and suggest a poor prognosis. Other imaging studies can be used for radiotherapy planning and post-treatment follow-up, such as positron emission tomography (PET) and single photon emission CT (SPECT).MRS, PET or SPECT have been used to measure blood volume and metabolic activity, and increased blood volume and enhanced metabolic activity are not only associated with tumor recurrence, but also help to differentiate tumor recurrence from radiation necrosis.