Gadolinium: The New Gold Standard for Diagnosing Cerebellopontine Angle Tumors

Abstract

\s=b\All physicians involved with the diagnosis and management of patients with tumors in the temporal bone and cerebellopontine angle are faced with the challenge removing these tumors while preserving hearing. Part of the challenge is to make the diagnosis while the tumor is still small enough to attempt a hearing-conservation surgical approach. Air-contrast (air cisternography) computed tomography is the "gold standard" by which all techniques of diagnosis are compared. Most physicians, however, are reluctant to use this test as a screen for tumors because of the associated morbidity, time, and expense. We present three case reports of contrast-enhanced magnetic resonance imaging for the detection of small intracanalicular or cerebellopontine angle tumors, and review the literature of this new and exciting technology. We feel that gadolinium-enhanced magnetic resonance imaging is now the procedure of choice for evaluating patients with suspected temporal bone tumors. (Arch Otolaryngol Head Neck Surg. 1989;115:1244-1247 Diagnosing cerebellopontine (CP) angle tumors is a challenge that faces otolaryngologists/head and neck surgeons each time they are con¬ fronted with a patient who exhibits unexplained sensorineural hearing loss, abnormal impedance test results, or abnormal auditory brain-stem re¬ sponses. It should be the goal of all physicians who see these patients to make the diagnosis early in the course of the disease in order to attempt hearing-preservation surgery. Even with the liberal use of computed tomo¬ graphic (CT) scanning, with or without contrast agent, it is possible to miss small acoustic tumors, especially those that are solely intracanalicular.1 There have been numerous reports of hearing preservation following removal of small, primarily intracanalicular acoustic tumors.The recent advent of magnetic reso¬ nance imaging (MRI) permits screen¬ ing of patients for acoustic tumors without exposure to ionizing radiation. There is also no risk of allergic reac¬ tions to contrast agents with plain MRI, as there is with iodinated-agent contrast CT. There are reports that MRI is more accurate than plain or contrast CT for diagnosing acoustic tumors, and in many medical centers, MRI has replaced CT scanning for the diagnosis of cerebellopontine angle tu¬ mors. However, there have recently been cases of acoustic tumors missed on MRI scans but picked up by aircontrast CT scanning (air cisternography).2 Because of these reports, most otologists feel that air-contrast CT scanning is still the "gold stan¬ dard" for acoustic tumor diagnosis.Air-contrast CT scanning is not without risk. Headache and stiff neck associated with air cisternography can persist for up to 3 or 4 days. This may be associated with a persistent cere¬ brospinal fluid leak. Air-contrast CT has a recognized incidence of false-positive diagnoses. This may precipitate unnecessary surgery.3 It is for these reasons that a search for a more reliable, less morbid method of diagnosing acoustic tumors exists. There have been studies to de¬ ...

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