Diagnosis of epidermoid cysts by metrizamide CT cisternography

Summary The authors describe three cases of intracranial epidermoid cysts specifically diagnosed by metrizamide CT cisternography. In CT cisternography of epidermoid cysts, metrizamide enters deep in the tumor clefts and depicts the lobulated margin of the tumor. We consider these findings are specific for this tumor and similar to the findings reported previously in pneumoencephalography or positive contrast cisternography.     

Determination of ventricular volume following metrizamide CT ventriculography

Summary Volume averaging, relatively slight differences in the mean attenuation coefficients of CSF and white/grey matter, and the irregular contours of the human ventricular system have so far seriously limited the accuracy of CT estimation of ventricular volume. Taking advantage of the high attenuation of metrizamide-containing CSF, we have developed three methods for computing ventricular volume after metrizamide CT ventriculography; these methods depend upon computer analysis of X-ray absorption data obtained from contiguous CT brain slices. All three methods were validated by CT scanning a formalin-fixed cadaver brain containing an epoxy-resin cast of the ventricular system. Calculated ventricular volumes were compared with the actual measured volume of the ventricular cast.     

Patterns of spinal cord atrophy by metrizamide CT

Forty patients with cervical myelopathy underwent high-resolution computed tomography (CT) with intrathecal administration of metrizamide for evaluation of cervical spinal cord atrophy. Thirty of them showed evidence of either focal atrophic distortion or generalized accentuation of the anatomic surface features of the spinal cord. Patients with a Chiari malformation or syringomyelia were excluded. The characteristic features in cervical spondylosis and canal deformity include flattening of the ventral surface of the cord, central infolding, beaking of the lateral funiculi, and wasting of the dorsal surface of the cord. Patients with motor neuron disease showed a combination of anterolateral and posterolateral atrophy reflecting underlying degeneration of the anterior horn cells and/or corticospinal tracts, respectively. Those with monomelic motor neuron disease had a striking ipsilateral hemiatrophy of the spinal cord. Among those presenting with spastic paraparesis, seven with clinically definite multiple sclerosis showed diffuse atrophy or focal degeneration due to a localized plaque of demyelination. Two cases of cord neoplasm showed atrophy secondary to ascending or descending degeneration of the long tracts.     

Cerebrospinal fluid imaging using serial metrizamide CT cisternography

Summary Twenty-five patients studied by serial metrizamide (Amipaque) CT cisternography were used to analyze CSF kinetics. Delayed CSF flow patterns were noted in 7 patients, while intermediate patterns occurred in 4. The abnormal cisternogram was characterized primarily by ventricular reflux and stasis and secondarily by diminution of the parasagittal blush and a periventricular rim of decreased absorption. The intermediate group had minimal ventricular stasis after 24 hours and a normal parasagittal blush. After clinical and biochemical evaluation of the patient with dementia, CT scanning is usually indicated. If a profile suggestive of communicating hydrocephalus emerges, CSF kinetics can be monitored dynamically by CT scanning with metrizamide enhancement.     

Delayed metrizamide CT enhancement of syringomyelia: postoperative observations

Delayed metrizamide computed tomography (CT) was performed both preoperatively and postoperatively in 11 syringomyelia patients. Change of syrinx size between the studies was easily assessed on CT. The morphologic change of the syrinx gave useful information about its continuity. One of our cases had reoperation as a result of this CT information. All cases with Chiari I malformation still showed filling of the syrinx cavity by metrizamide after posterior fossa decompression and obex plugging. This supports the idea that the abnormal fluid circulation maintaining syringomyelic cavities is more than just the flow through the obex to the central canal but may also be from fluid passage through the cord substance.     

Cervical radiculopathy: prospective evaluation with surface coil MR imaging, CT with metrizamide, and metrizamide myelography

A prospective study was undertaken to compare the accuracy of surface coil magnetic resonance (SCMR) imaging, metrizamide myelography (MM), and computed tomography with metrizamide (CTM) in the determination of cervical radiculopathy. Surgical findings were the objective measure of accuracy. Fifty-two patients underwent all imaging studies. Studies were evaluated for disease location and type (bone vs. soft tissue). Twenty-eight patients underwent subsequent cervical surgery at 39 levels form an anterior interbody approach. Predictions made with SCMR imaging were surgically confirmed in 74% of patients, with CTM in 85%, and with MM in 67%. There was 90% agreement with surgical findings when SCMR imaging and CTM were used jointly, and 92% agreement when CTM and MM were used jointly, In general, SCMR imaging was as sensitive as CTM for identification of disease level, but not as specific for type of disease. MM was the modality least specific for disease type. The major advantage of CTM was its ability to distinguish bone from soft tissue, for which contrast material is unnecessary. SCMR imaging is a viable alternative to MM and, together with computed tomography, if needed, provides a thorough examination of the cervical region.     

Dynamics of cerebrospinal fluid circulation evaluated by metrizamide CT cisternography.

Cerebrospinal fluid (CSF) circulation has been analyzed by metrizamide computed tomography (CT) cisternography in 46 patients. Included were 7 patients without any clinical evidence of impaired CSF circulation, and 39 with hydrocephalus due to various causes. CT cisternography delineated the anatomical structures of the CSF pathways clearly and accurately and enabled us to analyze ventricular filling in a quantitative manner. As a result, a new, more precise CT cisternographic classification of the CSF flow patterns has been established. On the basis of the presence of ventricular reflux and stasis, extent of ventricular filling, and convexity flow of metrizamide, seven groups of flow patterns have been defined.     

Comparison of iohexol and metrizamide in dynamic CT of the upper abdomen

Contrast enhancement (CE) of the aorta, liver and spleen obtained with non-ionic monomer of contrast media (CM) iohexol and metrizamide, was studied by dynamic computerized tomography in 18 and 14 patients, respectively. Six scans per minute were performed during 2 minutes and then single scans were taken at 3, 4 and 5 minutes after intravenous bolus doses of 18.5 g iodine. The mean CE and the pattern of washout with these two CM were similar in spite of their different molecular structure and physiochemical properties.     

Posterior fossa extraaxial cyst: diagnosis with metrizamide CT cisternography.

This study describes a new technique for the study of posterior fossa extraaxial cysts. Using metrizamide (Amipaque) CT cisternography, a rapid, simple, low morbidity method is now available which gives both anatomic and physiologic information that may obviate the need for pneumoencephalography and angiography. Two cases are reported; in a third the diagnosis was definitively excluded. By doing serial CT scans following the intrathecal introduction of metrizamide, data concerning the diffusion characteristics of these cysts as well as the accompanying hydrocephalus are obtained.     

Conventional and CT metrizamide myelography in Arnold-Chiari I malformation and syringomyelia

Four normal controls and 26 cases of Arnold-Chiari I malformations and/or syringomyelia were reviewed. The pathologic cases included five isolated Arnold-Chiari I malformations, nine communicating syringomyelia, five idiopathic syringomyelia, four posttraumatic syringomyelia, one syringomyelia with hemangioblastoma, and two postshunt syringomyelia. The objectives of this study were to compare the accuracy of conventional metrizamide myelography with CT metrizamide myelography and to study indirectly the hydrodynamics of CSF flow in syringomyelia by comparing the sequential enhancement patterns of the spinal cords and cord cavities in the different groups of patients. Twenty-five patients underwent conventional metrizamide myelography immediately before CT metrizamide myelography, and one patient underwent CT metrizamide myelography only. Scans were obtained 1-2 hr, 4-8 hr, and 12-24 hr after injection of metrizamide, but not all patients were scanned during all three intervals. CT metrizamide myelography was found to be more sensitive than conventional metrizamide myelography in the diagnosis of both Arnold-Chiari I malformation and syringomyelia. Performing just an immediate and a delayed scan was found to be more cost-effective than doing all three scans. Contrary to previous reports, it was found that delayed (12-24 hr) scans demonstrated more syrinx cavities than intermediate ones. In studying the sequential enhancement patterns of the spinal cords and cord cavities, some interesting trends were observed that tend to support the theories of Aboulker and of Ball and Dayan of transneural passage of CSF into cord cavities in syringomyelia.     

Comparison of metrizamide CT cisternography with radionuclide cisternography in abnormal cerebrospinal fluid dynamics

Summary Metrizamide CT cisternograms were performed on 39 patients with a clinical diagnosis of CSF abnormalities; 20 of these patients underwent radionuclide cisternography as well. Comparison of metrizamide CT and RN cisternography revealed good correlation in the degree, extent, and time sequence of ventricular reflux as well as the extent of cortical staining and cisternal filling. Metrizamide cisternography had the advantage of excellent anatomic detail and lower exposure dose, although minor complications were more frequent with this technique. Metrizamide CT cisternography has a potential to become the preferred method of evaluating patients with abnormal CSF dynamics.