Key points for MRI diagnosis of brain cancer

The emergence of magnetic resonance imaging (MRI) technology has provided a new means for the diagnosis of brain cancer, with advantages such as no X-ray radiation, high contrast, and multi-layer scanning and reconstruction. The key points of MRI diagnosis of brain cancer are:

1. Location of the tumor

Distinguishing whether the tumor is located inside or outside the brain is the first step of MRI examination. In order to better distinguish this problem, T1-weighted images are key because they are conducive to the display of pathological anatomical relationships. In order to clarify whether the brain pool and sulci are widened or whether they are shifted toward the ventricles, T2-weighted images are indispensable to facilitate comparison with the cerebrospinal fluid signal in the ventricles.

2. Tumor signal characteristics

Most tumors show low signal on T1-weighted images and high signal on T2-weighted images due to increased free water inside and/or outside tumor cells, which constitutes the common feature of signal changes in these tumors. Brain cancer signals are mostly manifested as uneven signal intensity, but some benign tumors also show uneven signal intensity when cystic changes, necrosis, hemorrhage, and calcification occur.

3. Tumor margins

The edges of brain cancer lesions are often unclear and irregular, and they infiltrate into surrounding tissues. Special attention should be paid to tumors with a diameter greater than 4 cm and clear edges, that is, tumors suspected of having a pseudocapsule.

4. Blood supply to the tumor

T2-weighted images are helpful in displaying tumor blood vessels, which may appear as curved or dot-shaped low signals. Some may appear as tree-root-like low signals at the bottom of the tumor, and then appear as scattered curved or dot-shaped signals after entering the tumor, indicating that the tumor has a rich blood supply.