ABSTRACT
Laboratory examination By far the most important element in the evaluation of patients suspected of harboring an intracranial tumor is the magnetic resonance image (MRI). Often, MRI performed before and after the injection of contrast material (gadolinium) is the only laboratory test required prior to initiating therapy. At other times, more extensive evaluation is required, as indicated in the paragraphs below. With very few exceptions, a negative MRI in a patient suspected of harboring an intracranial mass lesion effectively excludes that diagnosis. This, of course, assumes that the scan is of high quality, that it has been read correctly and that it has been performed with injection of contrast. The clinician should review each MRI with the neuroradiologist, paying careful attention to the area, if any, of clinical interest suggested by the history or examination. Early in their course, tumors may be either missed or confused with ischemic changes, particularly in the elderly. We do not suggest that every patient with a headache receive an MRI2 or that the history and physical findings not be meticulously reviewed before ordering an image, but we believe that, for most patients suspected of harboring an intracranial mass, MRI is the first and often the only step required for diagnosis.
