Charles M. Citrin

A study of computer-assisted tomography I. The incidence of positive CAT scans in an asymptomatic group of patients

In order to study the type and number of CAT scan abnormalities of the lumbar spine that occur in asymptomatic people, 52 studies from a control population with no history of back trouble were mixed randomly with six scans from patients with surgically proven spinal disease, and all were interpreted by three neuroradiologists in a blinded fashion. Irrespective of age, 35.4% (26.6%, 51.0%, and 31.3%) were found to be abnormal. Spinal disease was identified in an average of 19.5% (23.8%, 22.7%, and 12.5%) of the under 40-year-olds, and it was a herniated nucleus pulposus in every instance. In the over 40-year-old age group, there was an average of 50% (29.2%, 81.5%, and 48.1%) abnormal findings, with diagnoses of herniated disc, facet degeneration, and stenosis occurring most frequently.

Combined Clinical and Computed Tomographic Diagnosis of Primary Lacrimal Fossa Lesions

We studied 39 patients who had solid mass-lesions primary in the lacrimal gland by computed tomography and reviewed their clinical histories. Twenty-three patients had either inflammatory conditions (16 cases) or lymphoid tumors (seven cases), with average symptomatic periods of less than a year. In this group, soft-tissue contour analysis in the axial and corneal projections demonstrated diffuse, compressed, and molded enlargements of the lacrimal gland in an oblong fashion, and there were no associated bone defects. Sixteen parenchymal benign or malignant tumors (six benign mixed tumors, one schwannoma, and nine malignant epithelial tumors) exhibited rounded or globular soft-tissue outlines and were frequently associated with contiguous bone changes. The benign tumors had smooth encapsulated outlines at their margins, whereas the malignant tumors displayed microserrations indicative of infiltration. The patients with the benign mixed tumors had had symptoms, on the average, for more than a year, whereas those with epithelial malignancies became symptomatic or had a preexisting benign mixed tumor that became exacerbated in periods of less than six months. Contour analysis of the soft-tissue mass depicted in coronal and axial tomograms is a valuable adjunct that leads to more accurate preoperative diagnosis when combined with a radiographic search for bone changes and the clinical history. Once a diagnosis regarding the presumptive lesional family has been made preoperatively, corticosteroid therapy may be instituted for acute inflammation and biopsies through the eyelid should be performed for suspected chronic inflammations, lymphoid lesions, or epithelial malignancies. A lateral orbitotomy without prior biopsy should be performed for rounded, well-encapsulated masses of long duration that are likely to be benign mixed tumors.

Combined Clinical and Computed Tomographic Diagnosis of Orbital Glioma end Meningioma

The clinical information on 22 patients with orbital optic nerve gliomas and 47 patients with meningiomas was correlated with computed tomographic findings obtained in both axial and coronal studies. Most of the gliomas occurred in children, although 7 patients presented after 20 years of age. Among the patients with meningiomas, the majority were women in early middle age, although two tumors occurred in children less than 20 years of age. Low grades of proptosis (median, 2 mm for both tumors), frequent significant visual field obscurations with eye movements, and opto-ciliary shunt vessels pointed toward the diagnosis of an optic nerve tumor. Patients with gliomas generally manifested massively swollen fusiform optic nerves with clear-cut margins due to circumscription by an intact dura. Kinks and bucklings of the optic nerve as well as infarctive cysts distinguished the glioma CT-scan patterns from the meningiomas. Distinctive axial CT-scan features of the meningiomas not shared by the gliomas were narrowly and diffusely enlarged nerves with polar expansions either at the orbital apex or immediately behind the globe; calcification; irregular excrescent margins signifying extradural invasion into the orbital soft tissues; a negative optic nerve shadow running down the center of the lesion; and bone erosion near the orbital apex. Coronal studies often revealed irregular margins signifying transgression of the dura. A diffusely and narrowly enlarged optic nerve shadow with regular margins (intrasheath lesions) was the one morphologically overlapping pattern displayed by 11 meningiomas and three gliomas. In these cases there tended to be more profound visual loss in the gliomas compared with the meningiomas, as well as the more frequent presence of opto-ciliary vessels in the meningiomas. Arteriography may be helpful in this particular category by demonstrating a tumor blush for the meningiomas, whereas this finding is typically absent with optic nerve gliomas. Meningiomas may be very closely simulated by dural or intraneural inflammations.

Magnetic resonance demonstration of normal CSF flow.

The magnetic resonance (MR) imaging appearance and incidence of flowing cerebrospinal fluid (CSF) in the brain were investigated. The MR scans of 46 randomly selected patients with normal examinations were retrospectively reviewed. All patients were studied using both T2-weighted and T1-weighted spin-echo pulse sequences. Thirty-one patients (67%) had decreased intensity in the aqueduct of Sylvius on the T2-weighted images when compared with the intensity of CSF in the lateral ventricles. This was termed the CSF flow-void sign. The feature was present in the caudal fourth ventricle in 15 patients (32%) and in the third ventricle in two patients (4%) on T2-weighted scans. It was seen in only 13% of patients on T1-weighted scans. It is believed the CSF flow-void sign represents pulsatile CSF flow. Its recognition is important because it explains the inhomogeneity in the appearance of the CSF, which could be confused with pathologic processes. It may be valuable in the routine evaluation of MR examinations if it does reflect CSF circulatory dynamics.

The MR Appearance of CSF Pulsations in the Spinal Canal

We investigated the MR appearance and incidence of low-signal areas within the CSF of the spinal canal. Nonuniform areas of decreased signal intensity in intracranial CSF have been named the CSF flow-void sign (CFVS) and appear to be due to spin dephasing secondary to pulsatile CSF motion. Similar areas are seen in the spinal canal. The MR scans of 50 randomly selected patients, constituting a total of 63 spinal studies, were reviewed. There were 27 cervical, 16 thoracic, and 20 lumbar spine examinations. All patients were studied using T2-weighted and T1-weighted spin-echo pulse sequences. T2-weighted images were done with sufficiently long TE and TR to cause the CSF to appear hyperintense compared with brain and spinal cord tissue. Two patients with enlarged spinal canals and two patients with syringohydromyelia were also included to illustrate the appearance of prominent CSF pulsations. The CFVS was identified on T2-weighted scans in the cervical spinal canal in nine patients (33%), in the thoracic spinal canal in one patient (6%), and possibly in the lumbar spinal canal in two patients (10%). The CFVS was prominent in two patients with enlarged CSF spaces and was also seen in the intramedullary cavity of the patients with syringohydromyelia. The CFVS could obscure small dural lesions and, in some instances, simulate enlarged vessels. Recognition of the spinal CFVS is important to avoid the incorrect diagnosis of intraspinal lesions.

MR imaging of syringobulbia

The magnetic resonance (MR) examinations of 65 patients with syringomyelia were evaluated to determine the incidence and MR characteristics of syringobulbia. Syringobulbia was identified in 11 patients (17%), 10 of whom had communicating syringomyelia (associated with the Chiari I malformation) and one idiopathic syringomyelia. The cavities extended from 5 to 20 mm above the plane of the foramen magnum. Two types of syringobulbia were identified. The 10 patients with Chiari I malformation had thin clefts or slits extending into the medulla. These cavities were much smaller than the cervical cavities. The other patient had saccular syringobulbia in which the medullary cavity was similar to the cervical syrinx cavity. The T1-weighted images were most useful in detection of syringobulbic cavities. The theory of syringobulbia development and a brief review of the literature are included.

EEG and neuroimaging localization in partial epilepsy

We have studied cortical localization provided by surface and sphenoidal electroencephalograms (EEGs) and that of computed tomography (CT), magnetic resonance imaging (MR) and single photon emission tomography (SPECT) in 58 patients with partial epilepsy. Each patient had EEG, MR and SPECT during a hospitalization period of 1-2 weeks. CT scans were obtained either during the same period or had been performed in the preceding year. EEG evaluation consisted of 3-5 days of continuous monitoring including video-telemetry and ambulatory recording as well as conventional EEGs with special electrode placements. Additionally 33 of 58 patients (55%) who were potential surgical candidates had sphenoidal recordings. All patients had an abnormal EEG which showed evidence of epileptic hyperexcitability. EEG abnormality was localized in 43 patients (74%). Neuroimaging studies were focally abnormal in 38 patients (66%); 12 CT (21%), 29 MR (50%) and 24 SPECT (41%). Thirty four of 43 patients with localized EEG had at least 1 focally abnormal neuroimaging study (79%), whereas 4 of 15 (27%) patients with non-localized EEG did so. Twenty-eight of 29 patients with focal MR (97%), 11 of 12 patients with focal CT (92%) and 20 of 24 patients with focal SPECT (83%) had a concordant focal EEG. EEG and neuroimaging localization agreed in all 15 patients in whom both MR and SPECT disclosed a concordant focal abnormality. This study demonstrates a significant (P less than 0.005) correlation between surface/sphenoid EEG and neuroimaging localization in partial epilepsy.

Magnetic Resonance Demonstration of Altered Cerebrospinal Fluid Flow by Obstructive Lesions

We investigated the MR imaging appearance of flowing cerebrospinal fluid (CSF) in the brain in the presence of obstructive lesions of the ventricular pathways. The pulsatile movement of CSF through the ventricular system is seen as an area of low signal intensity that has been termed the CSF flow-void sign (CFVS). This is best appreciated in areas of narrowing within the ventricular system; that is, the aqueduct of Sylvius, foramen of Magendie, and interventricular foramina. MR studies of 27 patients with lesions affecting the ventricular pathways were reviewed for the presence of the CFVS. Single-echo T1-weighted and T2-weighted multisection techniques were used in all cases. The CFVS was always seen more prominently on the T2-weighted images. The presence of the CFVS indicated patency of the ventricular pathway in which it was identified. The absence of the CFVS in the presence of hydrocephalus indicated that a possible obstructive lesion was present, but it did not directly indicate the level of the obstruction. The CFVS was absent in the aqueduct of Sylvius in 13 patients with obstruction or stenosis of the aqueduct, but it was also absent in one patient with a colloid cyst of the interventricular foramina. In three patients with preoperative and postoperative MR, the CFVS was seen in the area of interest only after resection of the obstructing lesion. We concluded that the presence of the CFVS is a useful indicator of the patency of the ventricular pathway in which it is seen. The absence of the CFVS at a location in which it is normally seen may indicate the presence of an obstruction, but it must be correlated with other signs to be interpreted correctly. (AJNR 7: 571-579, 1986