Computed tomography and positron emission transaxial tomography evaluations of normal aging and Alzheimer's disease.

Young normal subjects, old normal subjects, and patients with senile dementia of the Alzheimer's type (SDAT) were studied with both computed tomography (CT) and positron emission transaxial tomography (PETT). Increases in ventricular size with both aging and disease were measured. Regional glucose metabolic rate was not affected by age, but was markedly reduced in SDAT patients. These data indicate that in normal aging, structural brain changes may be more salient than biochemical changes. Although both structural and biochemical changes occur in SDAT, the biochemical changes are more marked. The results suggest that PETT is potentially more useful than CT in the in vivo diagnosis of SDAT.

Computed tomography evaluations of brain-behavior relationships in senile dementia of the Alzheimer's type.

Neuropathological investigations have demonstrated brain-behavior relationships in senile dementia of the Alzheimer's type (SDAT), but CT studies have not produced consistent findings. We hypothesized that these discouraging results were in part due to limitations in the methods of CT scan evaluations, and to non-homogeneity of patient populations. The present study examined 43 out-patients with the presumptive diagnosis of SDAT using 37 cognitive test measures and 3 independent CT evaluation strategies. The CT methods included a new rank ordering procedure and two previously used techniques, physical measurement and 4-point rating. Highly significant (p less than or equal to 0.01) brain-behavior correlations were attained using the ranking and rating procedures for evaluation of ventricular and cortical pathology. It was found that rank ordering has high interrater reliability and is superior to the other methods for the evaluation of the ventricular system. The physical measurement of the third ventricle is the single most powerful linear correlate of cognitive impairment. Measurement of cortical sulci are of no correlational significance. Multiple regression analyses indicated that global assessments are the best cognitive predictors of both ventricular and cortical pathology. Thus the present study has demonstrated brain-behavior relationships in vivo in SDAT.

Microembolization techniques of vascular occlusion: radiologic, pathologic, and clinical correlation.

Vascular occlusion is described using microemboli of a predetermined size for the treatment of neoplastic conditions with a "capillary barrier." Particulated microemboli of either 40--60 micron Gelfoam powder or 200--1,000 micron polyvinyl alcohol foam (PVA) are best. Fluid embolic agents such as silicone fluid are used in lesions without a capillary barrier. The radiographic, pathologic, and clinical results in three patients are described in detail. Microembolization is useful in the treatment of neoplastic conditions for it produces tumor necrosis in addition to hemostasis.

Functional anatomy of the facial vasculature in pathologic conditions and its therapeutic application.

The authors describe the functional anatomy of the facial vascular system, using the anastomoses between the facial, maxillary, transverse facial, lingual, and ophthalmic systems to selectively identify the blood flow to a specific territory for embolization and posttreatment evaluation of hemangiomas. In three patients the specific vascular patterns are described and the usefulness of understanding the regional functional anatomy is illustrated for successful embolotherapy of these malformations.

Air-CT cisternography and canalography for small acoustic neuromas.

Disenchantment with the limitations, and in some cases the morbidity, of currently used radiologic techniques for the demonstration or exclusion of small acoustic neuromas prompted development of an examination using small amounts of intrathecal air and computed tomography (CT). A prospective study was designed to evaluate air CT cisternography/canalography, wherein patients with the clinical symptoms of acoustic neuroma but with negative enhanced CT, were evaluated by metrizamide CT cisternography followed by air CT cisternography/canalography. Pantopaque cisternography was then performed as a control procedure. Four patients had surgically proven tumors. In 13 others, accumulated evidence indicated no tumors were present. Results suggest that air-CT cisternography is superior to all other diagnostic methods in defining small acoustic neuromas, and may exclude an intracanalicular lesion without the potential hazards of Pantopaque cisternography or high concentration metrizamide tomocisternography. With air-CT cisternography, there were no errors in this series.

Imaging factors influencing spine and cord measurements by CT: a phantom study.

Metrizamide computed tomography (CT) of the spine allows evaluation of the contents and measurement of the size of intracanalicular structures. The relative size (linear and area measurements) of spinal structures can be changed by varying imaging factors or the density of intrathecal contrast material. Two phantoms, one consisting of rods embedded in a plastic cylinder and the other of a vertebral body with a central rod simulating spinal cord, were evaluated with varying imaging factors (window width and window level) and different contrast concentrations within the surround. It was found that wide window widths allowed the most consistent measurements independent of window level, that a window level midway between the CT number of rod and surround would facilitate uniform measurements independent of window width, and that the use of high concentrations of contrast material (high CT number) in the surround, in combination with a wide window width, was most effective in establishing consistent measurements.

Parenchymal CT correlates of senile dementia (Alzheimer disease): loss of gray-white matter discriminability.

Neuropathologic studies have defined gross anatomic (structural) as well as histologic (parenchymal) changes of senile dementia (Alzheimer disease). This investigation suggests that loss of gray-white matter discriminability by computed tomography (CT) is related to cognitive impairment in this disease. Discriminability is defined as the relative ease of visual differentiation between gray and white tissues. Twenty-six elderly patients with dementia were subjected to extensive psychometric evaluation, a medical and neurologic examination, and CT scanning. Gray and white matter changes were assessed by subjectively evaluating three brain levels, the basal ganglia, the centrum semiovale, and the high convexity, on a five point scale. Quantitated gray and white matter scores were also obtained by sampling CT attenuation values. In addition, CT structural changes were evaluated by previously reported methods. there were significant correlations (P less than 0.05) between the subjectively assessed loss of gray-white matter discriminability at all brain levels and the measures of cognitive decline. At the high convexity level 91% of cognitive measures correlated with loss of gray-white discriminability. In the same patient group no gray-white discriminability correlation with age was demonstrated suggesting that gray-white discriminability does not simply change with age.

Posttraumatic syrinx formation: experimental study.

An experimental study was performed to examine posttraumatic spinal cord cavitation in an animal model by evaluating immediate and delayed computed tomographic (CT) scans obtained after administration of intrathecal contrast material. Four cats underwent midthoracic laminectomy and spinal cord contusion using a standard 400 g-cm model. All animals were studied by CT with intrathecal contrast enhancement before and 4-5 days, 3-4 weeks, and 7-13 weeks after experimental cord contusion. Either metrizamide or iopamidol was used as the contrast agent. Two of the four cats had CT and pathologic evidence of cord cavitation at the site of injury. Another animal had uptake of contrast material into the spinal cord without pathologic evidence of cyst formation, which was believed to represent malacic change. The fourth animal had a normal-appearing cord by both CT and pathologic criteria. Animals that received metrizamide after cord contusion had generalized myoclonic seizures. This did not occur when iopamidol was administered.

Vasospasm secondary to ruptured aneurysm: assessment by digital intravenous angiography.

Digital intravenous angiography was used for the documentation and evaluation of cerebral vasospasm secondary to acute ruptured aneurysm. Attenuation of vessel caliber and/or generalized poor visualization of intracranial arteries and prolongation of circulation time were observed in seven patients with the acute clinical diagnosis of cerebral vasospasm. Posttreatment intravenous angiography demonstrated improvement in both arterial caliber and circulation time in six patients who responded to medical therapy for vasospasm. Digital intravenous angiography allowed repeat investigations of the intracranial vasculature safely and quickly without undue risk to the critically ill patient.

Comparison of radiographic quality and adverse reactions in myelography with iopamidol and metrizamide.

A randomized double-blind study was conducted to compare the radiographic quality and adverse reactions in myelography of the two nonionic water-soluble contrast media, iopamidol and metrizamide. A total of 46 myelograms were obtained, 28 with iopamidol and 18 with metrizamide. Untoward reactions consisted of nausea, headaches, back and leg pain, neuropsychiatric findings, and urinary retention. Iopamidol caused no reactions in 20 of the 28 cases, while metrizamide caused no reactions in only three of 18 cases. Film quality evaluation showed 22 of the 28 studies with iopamidol were judged excellent, whereas only 11 of the 18 metrizamide studies were judged excellent. The results of this study suggest that iopamidol produces better quality studies with fewer and milder adverse reactions than metrizamide.

CT prognostic criteria of survival after malignant glioma surgery.

The serial pre- and postoperative computed tomographic (CT) scans of 115 patients entered in the Cooperative Brain Tumor Study between 1975 and 1982 were analyzed in order to define CT prognostic criteria and to test the hypothesis that radical glioma surgery prolongs patient survival. The CT parameters of mass size, associated edema, and intensity of enhancement were quantitated on all scans. Clinical parameters evaluated included gender, age, length of survival, and useful (Karnofsky greater than 30) survival. Data analyses indicated postoperative residual tumor burden was inversely related to length of survival (p less than 0.01). Postoperative associated edema and intensity of image enhancement were also of prognostic value and showed an inverse relation to survival. Younger patients proved more likely than older patients to attain long-term survival. Residual tumor burden of less than 45 mm diameter on postoperative CT scans was associated with 70% chance of long-term survival. These findings support the radical surgical management of glioma.

Diagnosis of carotid artery stenosis: comparison of 2DFT time-of-flight MR angiography with contrast angiography in 50 patients.

Fifty patients underwent 2DFT time-of-flight MR angiography and intraarterial contrast angiography for evaluation of possible carotid atherosclerotic disease. The MR angiography technique employed contiguous axial flow-sensitive (short TR/TE) slices that were reformatted and postprocessed by using a maximum-intensity projection algorithm to provide 16 angiographic views of the carotid arteries. Both studies were independently reviewed by two observers in a blinded manner. Carotid arteries were categorized as normal, mildly stenotic, moderately stenotic, severely stenotic, or occluded. For the 94 carotid arteries available for review, one observer reported a 70% agreement between the two techniques and the second observer reported a 56% agreement (p = .0001). The best correlation was in the severely stenotic category and the worst was in the occluded category. Agreement between observers was 67% for MR angiography and 72% for contrast angiography, which was similar to that between the two techniques. Although not all carotid atherosclerotic disease was visualized equally well, 2DFT time-of-flight MR angiography had a good overall correlation with the "gold standard" of intraarterial contrast angiography, supporting its use as a screening technique. While further improvements are needed, use of MR angiography as the primary diagnostic tool for many patients with suspected carotid stenosis should continue to increase.

MR of spinal cord ganglioglioma.

PURPOSE: Our purpose was to describe the MR imaging features in a series of spinal intramedullary gangliogliomas and to compare these findings with the MR features of intramedullary astrocytomas and ependymomas. METHODS: A retrospective analysis was performed of 76 MR examinations in 27 patients with histologically proved spinal ganglioglioma; these were then compared with imaging findings in a representative sample of histologically proved spinal cord astrocytomas and ependymomas. RESULTS: Statistically significant observations regarding spinal gangliogliomas included young age of the patients (mean, 12 years), long tumor length, presence of tumoral cyst, presence of bone erosion and scoliosis, absence of edema, presence of mixed signal intensity on T1-weighted images, and presence of patchy enhancement and cord surface enhancement. A trend (not statistically significant) was noted for holocord involvement and lack of magnetic susceptibility. CONCLUSION: Spinal ganglioglioma can be strongly suspected if MR images reflect the above criteria; however, the ultimate diagnosis still depends on radical resection and appropriate histopathologic investigation.

Regional correlation of PET and CT in senile dementia of the Alzheimer type.

Alzheimer disease is manifested by both widespread and regionally restricted brain changes, some of which have recently been identified in vivo with computed tomography (CT) and positron emission tomography (PET). This is a report of the regional correlation of CT and PET measurements in 19 carefully diagnosed subjects comprising 11 controls and eight patients with senile dementia of the Alzheimer type. Regional CT attenuation values did not discriminate between the two groups, but PET using 18F-2-deoxy-2-fluoro-D-glucose demonstrated significant regional reductions (range, 21%-28%) in glucose utilization in the Alzheimer group. PET measures were also more consistently related to cognitive decline. The correlation between CT structural measures and PET metabolic measures demonstrated consistent relations between widespread PET regions and CT changes in the thalamus, posterior limb of the internal capsule, and temporal lobes. However, CT changes in the frontal white matter, caudate nucleus, and anterior limb of the internal capsule were not related to any regional PET changes. These data support previous findings of temporal lobe involvement in Alzheimer disease and suggest the involvement of structures in the region of the third ventricle.

Positron emission tomographic studies of aging and Alzheimer disease.

In this study the positron emission tomographic (PET)-18F-2-deoxy-2-fluoro-D-glucose (FDG) technique was used to study both normal aging and senile dementia. The results derived from 15 young normal subjects (mean age, 26 +/- 5 years) and 22 elderly normal subjects (mean age, 66 +/- 7 years) failed to indicate significant metabolic changes associated with age. A group of 24 patients with senile dementia (mean age, 73 +/- 7 years) showed consistent diminutions in regional glucose use relative to the elderly normals. Across all brain regions the diminutions were 17%-24%. There were also significant correlations between the measures of glucose use and the measures of cognitive functioning. Discriminant function classification analysis results indicate that better than 80% classification accuracy can be achieved for individual PET measures. These data suggest a possible future diagnostic use of PET in senile dementia.

The value of dynamic scanning.

Dynamic CT is a proven alternative to angiography in the assessment of parasellar lesions. Characteristics of the tumor, such as vascularity or cystic regeneration, are easily demonstrated. Dynamic CT is able to diagnose conclusively an intracranial aneurysm and to follow the therapeutic course after ligation of the carotid artery. The application of dynamic CT to cerebrovascular disease is limited by the lack of subsecond sequencing in fragmentation scans. Its importance in documenting the patency of the cervical internal carotid artery that appears to be occluded angiographically cannot be overstressed.

Potential misinterpretation of cervical spondylosis with cord compression caused by metallic artifacts in magnetic resonance imaging of the postoperative spine.

Tiny metallic particles produced by the contact of untempered surgical instruments with a diamond drill produce magnetic susceptibility artifacts that can both limit the diagnostic quality of postoperative magnetic resonance imaging of the cervical spine and cause diagnostic error. A case of cervical pseudospondylosis with apparent cord compression due to such an artifact is presented. The source of these metallic particles is considered, and the nature of the susceptibility artifact is discussed.

Brain tumors studied by computerized tomography.

A brief description of the method and clinical application of CT is given. Various features and absorption values of different intracranial neoplasms are described and compared. The effects of CT on other special diagnostic procedures are discussed. It is emphasized that contrast medium enhancement significantly increases the sensitivity and specificity of the technique when applied to patients who have or are suspected of having cerebral neoplasms.