Abstract
Context: Intravenous administration of contrast materials in imaging studies is critical in detection of lesions which may be otherwise missed. Both computed tomography (CT) and magnetic resonance imaging (MRI) benefit from addition of contrast agents. MRI is superior to CT in evaluation of most diseases involving the brain and spine. Contrast resolution and anatomic display are two of the main factors that contribute to the superiority of MRI. Disorders affecting the cerebrospinal fluid (CSF) containing spaces may be under-diagnosed or poorly understood on conventional CT or MRI. Although intrathecal CT-cysternography/myelography with water-soluble iodinated contrast media and radionuclide cisternography (RC) are routinely used, few studies have dealt with intrathecal use of Gadolinium (gadopentetate dimeglumine) (Gd) although it appears superior to both techniques and seems to be potentially less risky. Currently, Gdenhanced MRI cisternography/myelography is not approved by the US Food and Drug Administration and is used offlabel. Objective: i-To summarize the existing literature regarding the use, safety, and indications of intrathecal and intraventricular use of paramagnetic contrast MRI agents, specifically intrathecal Gd-enhanced cisternography or myelography; ii-To outline the technical procedures, safety, and indications, and iii-To provide a critical comparison with other approved studies such as CT-cysternography/myelography and RC. Methods: We reviewed the literature by MEDLINE searches using the terms gadopentate dimeglumine, gadodiamide, diethylenetriaminepentaacetic acid (Gd-DTPA), MRI-cysternography/ventriculography, intrathecal Gd-enhancement, CSF leaks, intracranial hypotension syndrome, spontaneous rhinorrhea and otorrhea, radioisotope cisternography. Reference lists of these articles and ongoing investigations in this area were used as well. Evidence Synthesis: There are no grade III studies of scientific evidence in comparative studies. The major drawback of available comparative studies, which evaluate the accuracy of each imaging technique, including enhanced-MR or CTcisternography/ myelography or RC, is the lack of a recognized “gold standard” imaging study, so that sensitivity or specificity of each imaging study cannot be fully assessed. Currently available studies demonstrate a superiority of intrathecal Gd MRI over CT cisternography/myelography and RC in some applications such as spontaneous or postoperative cranial fistulae, hypotension intracranial syndrome, and specific neurological/neurosurgical diseases of children. Superiority and safety of Gd-enhanced MR cisternography/ventriculography rests on absence of ionizing radiation, absence of bone artifacts, and superior spatial anatomic detail coupled with relatively high contrast resolution. Side effects and toxicity are low. Conclusions: It is unlikely that further studies will compare the efficacy of Gd-enhanced MR cisternography/ventriculography with their CT or RC counterparts since it is unethical to perform two intrathecal enhanced imaging examinations on the same patient. Although still not approved for clinical use worldwide, Gd-enhanced MR cisternography/ myelography seems to be clinically more useful and less risky than CT-cisternography/myelography and RC in certain complex central nervous system (CNS) diseases. Adverse effects, potential lumbar puncture-related side effects, and uncertain effects on the maturing brain and absence of long-term follow-up in patients who have undergone this procedure contribute to the underutilization of Gd-enhanced MR cisternography/myelography.
Keywords: Gd-DTPA, Intrathecal Gd-enhancement gadopentate dimeglumine, MRI-cysternography/ventriculography, CSF leaks, Intracranial hypotension syndrome
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