Brain Tumors: Primary - Diagnosis

(Page 2)

Other Imaging Techniques. Numerous other advanced or investigational imaging techniques include:

• Single photon emission tomography (SPECT) is similar to PET but is not as effective in distinguishing tumor cells from destroyed tissue after treatments. It may be used after CT or MRI to help distinguish between low-grade and high-grade tumors.
• Magnetoencephalography (MEG) scans measure the magnetic fields created by nerve cells as they produce electrical currents. It is used to evaluate functioning in various parts of the brain. However, this procedure is not widely available.
• MRI angiography evaluates blood flow. MRI angiography is usually limited to planning surgical removal of a tumor suspected of having a large blood supply.

---

---

Lumbar Puncture (Spinal Tap)

A lumbar puncture is used to obtain a sample of cerebrospinal fluid, which is examined for the presence of tumor cells. Spinal fluid may also be examined for the presence of certain tumor markers (substances that indicate the presence of a tumor). However, most primary brain tumors do not have identified tumor markers.

A computed tomography (CT) scan or magnetic resonance imaging (MRI) should generally be performed before a lumbar procedure to make sure that the procedure can be performed safely.

Click the icon to see an image of a lumbar puncture.

Biopsy

A biopsy is a surgical procedure in which a small sample of tissue is taken from the suspected tumor and examined under a microscope for malignancy. The results of the biopsy also provide information on the cancer cell type. Biopsies may be performed as part of surgery to remove a tumor, or as a separate diagnostic procedure.

In some cases, such as with brain stem gliomas, a standard biopsy might be too hazardous because removing any healthy tissue from this area can affect vital functions. In these cases, surgeons can use alternative techniques such as needle biopsy and stereotaxic biopsy. Stereotaxic biopsy is a computer-directed type of needle biopsy that uses images provided from MRI or CT scans to provide precise information on the tumor's location.

Review Date: 10/21/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).