Clinical subspecialties

Neuro-Imaging Resources: A Window on the Brain

MR - 3D image of brain

New imaging technologies have revolutionized both brain tumor surgery and radiation therapy. The Yale Brain Tumor Center Group is skilled in such techniques as positron emission tomography (PET), Single Photon Emission Computed Tomography (SPECT), functional magnetic resonance imaging (fMRI) and MR spectroscopy to ensure the most accurate pre-surgical planning and maximal resection of benign and malignant primary and metastatic brain tumors.

Functional magnetic resonance imaging (fMRI) allows physicians to map areas of the brain associated with vital functions such as speech, vision, hearing, taste, touch and voluntary movement. Sensory and motor activities alter the flow of blood and the use of oxygen in the areas of the brain involved in these functions, producing signals that can be detected by the MRI scanner. A functional MRI assessment before surgery clearly shows the differences in brain organization from one person to another and can be critical in determining the best surgical approach.

Functional MRI of the brain. The colored areas indicate the location of motor function (movement) within the brain.

A PET scan provides physiologic information about a brain tumor. A certain tracer substance is injected into a vein before the scan is done. A large number of malignant brain tumors take up this tracer which makes them visible on the scan whereas low-grade tumors remain 'cold'.

PET scan of a patient with a tumor involving the left side of the brain (right on the image).

A SPECT scan provides a blood perfusion map of brain lesions. It can help differentiating tumors from infectious or inflammatory diseases. It is also used to determine if certain tumors are amenable to specific types of 'targeted therapy'.

SPECT scan of a patient with a tumor at the base of the brain. This scan was used to determine if the patient was eligible for a certain type of treatment.

Magnetic resonance spectroscopy reveals a 'chemical fingerprint' of a brain tumor.

MR spectroscopy of normal brain tissue (left), a brain tumor (middle) and an area of necrosis (dead tumor cells; right) after radiation therapy. Each 'peak' represents a molecule containing protons. Peak height correlates with the relative concentration of each molecule which varies depending on the type of tissue within the area of interest.