Longitudinal evaluation of diffusion tensor imaging and cognition in systemic lupus erythematosus.

Objective This pilot study aimed to examine longitudinal changes in brain structure and function in patients with systemic lupus erythematosus (SLE) using diffusion tensor imaging (DTI) and neuropsychological testing. Methods Fifteen female SLE patients with no history of major neuropsychiatric (NP) manifestations had brain magnetic resonance imaging (MRI) with DTI at baseline and approximately 1.5 years later. At the same time points, a standardized battery of cognitive tests yielding a global cognitive impairment index (CII) was administered. At baseline, the SLE patients had mean age of 34.0 years (SD = 11.4), mean education of 14.9 years (SD = 2.1), and mean disease duration of 121.5 months (SD = 106.5). The MRI images were acquired with a 3T GE MRI scanner. A DTI sequence with 33 diffusion directions and b-value of 800 s/mm2 was used. Image acquisition time was about 10 minutes. Results No significant change in cognitive dysfunction (from the CII) was detected. Clinically evaluated MRI scans remained essentially unchanged, with 62% considered normal at both times, and the remainder showing white matter (WM) hyperintensities that remained stable or resolved. DTI showed decreased fractional anisotropy (FA) and increased mean diffusivity (MD) in bilateral cerebral WM and gray matter (GM) with no major change in NP status, medical symptoms, or medications over time. Lower FA was found in the following regions: left and right cerebral WM, and in GM areas including the parahippocampal gyrus, thalamus, precentral gyrus, postcentral gyrus, angular gyrus, parietal lobe, and cerebellum. Greater MD was found in the following regions: left and right cerebral WM, frontal cortex, left cerebral cortex, and the putamen. Conclusions This is the first longitudinal study of DTI and cognition in SLE, and results disclosed changes in both WM and GM without cognitive decline over an 18-month period. DTI abnormalities in our participants were not associated with emergent NP activity, medical decline, or medication changes, and the microstructural changes developed in the absence of macrostructural abnormalities on standard MRI. Microstructural changes may relate to ongoing inflammation, and the stability of cognitive function may be explained by medical treatment, the variability of NP progression in SLE, or the impact of cognitive reserve.

Effect of training and experience on qualitative and quantitative CT perfusion data.

BACKGROUND AND PURPOSE: To evaluate interobserver reliability of obtaining CT perfusion (CTP) data for qualitative identification of perfusion abnormality and quantitative assessment through regions-of-interest (ROIs) placement. MATERIALS AND METHODS: Six observers participated in the study (neuroradiology attending physician, neurology attending physician, neuroradiology fellow, radiology resident physician, senior and junior CT technologists). After a brief training session, each observer evaluated 20 CTP datasets for qualitative identification of a right- or left-sided perfusion abnormality or symmetric perfusion. Observers also placed a single ROI of standard size to obtain quantitative data on the most severely hypoperfused region. An additional 10 ROIs were placed on the cortex to quantitatively evaluate global cortical perfusion. Mean quantitative cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) values were analyzed. RESULTS: The kappa values for qualitative assessment of a perfusion abnormality ranged from 0.55 to 1.0. Coefficients of variation for quantitative assessment of ischemia/infarct region were 27.10% for CBF, 13.33% for CBV, and 4.66% for MTT. Coefficients of variation for quantitative assessment of global cortical perfusion were 11.88% for CBF, 13.66% for CBV, and 3.55% for MTT. The junior CT technologist and neuroradiology fellow showed significant differences compared with other observers for the ischemia/infarct region and global cortical perfusion, respectively. CONCLUSION: Overall, quantitative differences seen in this study would not necessarily affect quality of interpretation of ischemia/infarct region or global cortical perfusion. Therefore, obtaining qualitative and quantitative CTP data can reliably be performed in the clinical setting among observers with various levels of skill and experience when using a uniform and standard technique.

Diffusion anisotropy changes in the brains of professional boxers.

BACKGROUND AND PURPOSE: Professional boxing may result in brain injury. We hypothesize that quantitative MR diffusion imaging may be useful in determining early white matter changes. METHODS: Forty-nine professional boxers (age 30 +/- 4.5 years) and 19 healthy control subjects (age 32 +/- 9.5 years) were imaged on a clinical 1.5T scanner. None of the subjects had neurologic disorder or deficit. The average diffusion constant (D(av)) and diffusion anisotropy (FA) were determined pixel by pixel. Regional diffusion measurements were done in the corpus callosum (CC) and internal capsule (IC). The whole brain diffusion constant (BD(av)) was also determined. Student t test was used to analyze the diffusion difference between boxers and the healthy control subjects. P < .05 was considered statistically significant. RESULTS: Of the 49 professional boxers, 42 had normal conventional MRIs. The remaining 7 boxers had abnormal MR imaging findings dominated by nonspecific white matter disease. There was a significant difference in diffusion and anisotropy measurements in all the boxers compared with the healthy control subjects. In the boxer group, BD(av) increased and FA decreased significantly in the CC and posterior limb of IC. The measured FA and D(av) inversely correlated in regions of CC and IC in boxers but not in healthy control subjects. BD(av) also robustly correlated with both FA and D(av) in the splenium of CC in boxers. CONCLUSION: Increased BD(av) and the decreased FA in the CC and IC may represent preclinical signs of subtle brain injury in professional boxers.

Radiologic estimation of hematoma volume in intracerebral hemorrhage trial by CT scan.

BACKGROUND AND PURPOSE: Therapeutic intervention during the early stages of an intracerebral hemorrhage (ICH) might have value in improving clinical outcomes. During the 73-site International Recombinant Activated Factor VII Intracerebral Hemorrhage Trial, CT techniques were used to monitor the change in hematoma volume in response to treatment. The use of CT imaging technology served 3 functions: to provide accurate measurements of the change in hematoma volume, intraventricular volume (IVH), and edema volume; to evaluate the use of CT scans as a predictor of patient outcomes; and to demonstrate that hematoma volume can serve as a surrogate marker for ICH clinical progression. METHODS: The multicenter clinical trial received institutional review board approval and obtained informed consent from the patient or a legally acceptable representative (waived in a few cases of incapacity, according to local and national regulations). CT scans were used to quantify volumes of hemorrhage and to monitor evolution over a 72-hour period in patients with ICH treated with placebo or 40, 80, or 160 microg/kg of recombinant activated factor VII (rFVIIa). CT image data were transmitted digitally to an imaging laboratory and analyzed by 2 readers masked to patient and treatment data, by using Analyze software, a fully integrated toolkit for interactive display, processing, and measurement of biomedical image data. The use of this software enabled the evaluation of intraclass variability of CT scan interpretations. RESULTS: Interpretations of ICH and IVH volumes of CT scans in patients treated in this study showed minimal intraclass variability. Variability was greatest for interpretations of edema volume. CONCLUSION: These CT assessments of lesions could have value in future early hemostatic interventions in ICH patients.

Protrusion of the Infraorbital Nerve into the Maxillary Sinus on CT: Prevalence, Proposed Grading Method, and Suggested Clinical Implications.

BACKGROUND AND PURPOSE: The infraorbital nerve arises from the maxillary branch of the trigeminal nerve and normally traverses the orbital floor in the infraorbital canal. Sometimes, however, the infraorbital canal protrudes into the maxillary sinus separate from the orbital floor. We systematically studied the prevalence of this variant. MATERIALS AND METHODS: We performed a retrospective review of 500 consecutive sinus CTs performed at our outpatient centers. The infraorbital nerve protruded into the maxillary sinus if the entire wall of the infraorbital canal was separate from the walls of the sinus. We recorded the length of the bony septum that attached the infraorbital canal to the wall of the maxillary sinus and noted whether the protrusion was bilateral. We also measured the distance from the inferior orbital rim where the infraorbital canal begins to protrude into the sinus. RESULTS: There was a prevalence of 10.8% for infraorbital canal protrusion into the maxillary sinus and 5.6% for bilateral protrusion. The median length of the bony septum attaching the infraorbital canal to a maxillary sinus wall, which was invariably present, was 4 mm. The median distance at which the infraorbital nerve began to protrude into the sinus was 11 mm posterior to the inferior orbital rim. CONCLUSIONS: Although this condition has been reported in only 3 patients previously, infraorbital canal protrusion into the maxillary sinus was present in >10% of our cohort. Identification of this variant on CT could help a surgeon avoid patient injury.

Magnetic resonance imaging in amateur boxers.

Nine amateur boxers who participated in the 1985 and 1986 New York City Golden Gloves competition underwent detailed neurologic examinations and magnetic resonance (MR) scanning. All nine boxers were medically suspended secondary to a knockout or excessive head blows. Neurologic examination results and MR scans were normal in all nine boxers. Failure to detect abnormalities on the MR scan, by neurologic examination, or both in these amateur boxers may reflect several factors, including a small sample size, the duration between their last bout and neurologic evaluation, and the lower exposure to head trauma among amateur boxers compared with professionals.

Computed tomography in Herpes simplex encephalitis.

Eight patients with Herpes simplex encephalitis had computed cranial tomography (CT). In every case, areas of decreased attenuation were found in the temporal lobe(s); these areas extended to the insular cortex and often to the frontal or parietal lobes. This change developed between the third and the eleventh day of illness. It was present, sometimes only in retrospect, in patients who were alert as well as patients who were comatose. Compared to the isotopic brain scan, electroencephalogram, and cerebral angiogram, CT demonstrates changes that are indicative of H simplex early enough in the course of the illness to be therapeutically useful.

Computed tomography in cerebrotendinous xanthomatosis.

In nine patients with cerebrotendinous xanthomatosis (CTX), computed tomography (CT) demonstrated diffuse white matter hypodensity above and below the tentorium. This was attributed to sterol infiltration with secondary demyelination. In one patient, a focal right cerebellar hypodense lesion reflected a true xanthoma. These findings suggest that the neurologic symptoms, no matter how longstanding, result from metabolic encephalopathy rather than irreversible destruction of brain tissue by xanthomas.

Luetic meningitis with gumma: clinical, radiographic, and neuropathologic features.

A 28-year-old man had headache and unilateral third-nerve palsy as the presenting features of acute syphilitic meningitis, accompanied by an asymptomatic cerebral gamma.

Computed tomographic demonstration of cerebral edema in a child with galactosemia.

An eight-day-old male infant with galactosemia presented with signs of increased intracranial pressure and no evidence of intracranial infection or hemorrhage. Computed tomographic scans demonstrated the presence of diffuse cerebral edema. With treatment, the edema gradually resolved, although it persisted longer within the white matter and was associated with transient bilateral pyramidal tract signs.

Direct in vivo observation of transventricular absorption in the hydrocephalic dog using magnetic resonance imaging.

RATIONALE AND OBJECTIVES: A model of chronic noncommunicating hydrocephalus in canines was developed, and gadolinium-DTPA (Gd-DTPA)-enhanced magnetic resonance imaging, physiologic and morphologic studies were performed to investigate transventricular absorption of cerebrospinal fluid. METHODS: Chronic hydrocephalus was induced in 12 mongrel dogs by injection of a silastic mixture into the prepontine cisterns. Ventricular pressure was measured during the development of hydrocephalus, and lateral ventriculo-ventricular perfusions with Gd-DTPA were performed under controlled conditions during serial magnetic resonance imaging studies. RESULTS: Hydrocephalus developed over an average of 129 +/- 24 days after induction, and the intraventricular pressure increased from an initial level of 14 +/- 4 cm H2O to a stabilized plateau of 25 +/- 5 cm H2O. Increased signal intensity in the brain matter, as seen on magnetic resonance images of chronic hydrocephalic dogs perfused with Gd-DTPA in the lateral ventricles, was consistent with the presence of the contrast agent in the periventricular extracellular space. This increased signal intensity was not observed in control animals. CONCLUSIONS: These results provide direct evidence of transventricular absorption in chronic hydrocephalus.

MR imaging of cerebral vascular malformations.

Fifteen vascular malformations, including six supratentorial arteriovenous malformations (AVMs), three venous malformations, and six brainstem vascular malformations, were examined on 0.5 T magnetic resonance (MR) and GE 9800 and 8800 computed tomographic (CT) scanners. All the malformations were shown by MR, and the arterial and venous drainage of AVMs was precisely delineated. Hematoma was always differentiated from calcification by MR signal characteristics. Increased signal in the brain parenchyma was often seen adjacent to AVMs. The signal of blood within venous malformations altered with spin-echo techniques using various repetition times and was distinguished from rapidly flowing blood in AVMs that lacked signal in all imaging sequences. Brainstem malformations were seldom demonstrated by angiography. Hemorrhage was common and was invariably associated with multiple areas of absent signal that may have represented abnormal vessels. These appearances are distinct from those of intrinsic tumors and are probably pathognomonic of brainstem vascular malformations.

Detection of acute intracerebral hemorrhage on MR imaging: ineffectiveness of prolonged interecho interval pulse sequences.

MR imaging at 0.6 T was performed in 22 patients with acute (less than 7 days) intracranial hemorrhage to determine the efficacy of prolongation of the interecho interval, which has been demonstrated to enhance T2 shortening in vitro, as a method to improve the detection of hemorrhage in clinical imaging. The protocol included 750/33 (TR/TE), 2150/60,120 (short interecho interval of 60 msec), and 2150/120 (long interecho interval of 120 msec) sequences. Visual comparisons of the 2150/120 images obtained with the short and long interecho intervals demonstrated no difference in the degree of hypointensity in 21 of 22 cases. Quantitative comparisons demonstrated no statistically significant difference in the degree of maximal hypointensity, in the ease of detectability of hypointensity, or in the overall image contrast in 16 of 22 cases. We conclude that prolongation of the interecho interval is not a clinically useful technique to improve the detection of acute hemorrhage.

Diffusion changes in the aging human brain.

BACKGROUND AND PURPOSE: Quantifying changes in the human brain that occur as part of normal aging may help in the diagnosis of diseases that affect the elderly and that cause structural changes in the brain. We sought to assess diffusion changes that are inherently related to brain structure during aging. METHODS: MR scans were obtained from 11 healthy volunteers and 27 patients (ages 26 to 86 years [53.4 +/- 17.0 years]). Images acquired from the patients either showed no abnormalities, contained minimal periventricular white matter changes, or revealed focal lesions. Maps of the average diffusion constant (D(av)) were calculated for each subject. Changes in D(av) were determined with distribution analysis (histogram) for the entire brain and compared with region-of-interest measurements from the periventricular white matter and thalamus. RESULTS: Mean D(av) of the entire brain (0.74 +/- 0.02 x 10(-5) cm2/s) showed weaker age dependency compared with the periventricular white matter D(av)(0.76 +/- 0.04 x 10(-5) cm2/s). The D(av) of the thalamus D(av) (0.75 +/- 0.03 x 10(-5) cm2/s) had no age dependency. The age-dependent changes of entire brain D(av) may be significant for subjects older than 60 years compared with younger subjects. CONCLUSION: In this study, we observed minimal changes in the D(av) of the entire brain with aging. The mean D(av) of the human brain is nearly constant throughout most of adulthood.

Falx and interhemispheric fissure on axial CT: II. Recognition and differentiation of interhemispheric subarachnoid and subdural hemorrhage.

Interhemispheric hyperdensity or unenhanced computed tomography was originally considered a sign of subarachnoid hemorrhage, the "falx sign." It has since been identified as a normal feature and has also been seen with interhemispheric subdural hemorrhage. To determine the differential features of interhemispheric hemorrhage, 50 patients with subarachnoid hemorrhage and 32 patients with interhemispheric subdural hematomas were reviewed. Subarachnoid hemorrhage produced anterior interhemispheric hyperdensity only, with a zigzag contour and extension from the calvarium to the rostrum of the corpus callosum. Interhemispheric subdural hematomas produce unilateral crescentic hyperdensities that are largest in the posterior superior part of the fissure, behind and above the splenium of the corpus callosum. Interhemispheric hyperdensity in children is more complex. Because the anterior part of the fissure is narrow in younger patients, subarachnoid hemorrhage may go undetected. Likewise, interhemispheric subdural hematomas in children are smaller and more difficult to recognize. They produce asymmetric thickening of the falx shadow with extension over the tentorium. They are, however, of great significance since they are generally seen in abused patients and carry a poor prognosis.

The value of unenhanced scans in differentiating lesions producing ring enhancement.

Ring enhancement with contrast material is a nonspecific computed tomographic finding seen in a variety of lesions, including benign and malignant neoplasms, inflammation, infarction, and hematoma. This lack of specificity is especially troublesome in the differentiation of self-limiting disorders (infarction and hematoma) from progressive processes (tumor or abscess) potentially requiring surgical treatment. To determine whether more specific diagnoses were possible, 115 cases with ring lesions were retrospectively evaluated for the usefulness of precontrast scan features. The presence or absence of a complete ring proved useful. A complete ring on unenhanced scans effectively excluded self-limiting processes; it was seen in none of 18 infarcts or 11 hematomas. A complete ring on unenhanced scans occurred in 37 of 65 neoplasms, and was more common in metastatic disease (2:1) than in gliomas. A complete ring on unenhanced computed tomography was also seen in four of 15 pyogenic abscesses.

Axial CT recognition of anteroposterior displacement of fourth ventricle.

The recognition of anterior or posterior displacement of the fourth ventricle on axial computed tomography (CT) has proven to be difficult because the apparent position of this structure is variable and dependent on scanning angle. In most cases direct visualization of a lesion and its relationship to normal anatomic structures allows for the correct assessment. However, in some instances it would be advantageous for lesion localization to be able to identify relatively subtle displacements of the fourth ventricle. This is possible on CT by determining the position of this structure relative to Twining's line (the line between the tuberculum sellae and torcula). The position of the fourth ventricle, tuberculum sellae, and torcula relative to an arbitrary fixed point can be established in virtually all cases, and thus the position of the fourth ventricle relative to Twining's line can be determined. In a control group of 100 patients with normal CT examinations, the ratio of the distance from the tuberculum sellae to the center of the fourth ventricle and the distance from the tuberculum sellae to torcula (Twining's line) was between 0.47 and 0.53. In 66% of the cases the ratio was 0.49-0.51. THere were 54 posterior fossa masses evaluated by this technique. Determination of fourth ventricular position by this method proved to be of particular value in recognizing brainstem glioma, and in determining the site of origin of laterally placed posterior fossa masses.

Dural sinus thrombosis: verification with spin-echo techniques.

Although MR imaging is being used increasingly to detect dural sinus thrombosis, accurate evaluation of images has often been hindered by the presence of artifacts, especially flow-related enhancement, that may simulate intraluminal clot. We tried an approach with spin-echo techniques to eliminate flow-induced artifacts and, thus, facilitate the diagnosis of dural sinus thrombosis. In this investigation, a nonselective single-section spin-echo verification method was used as a prototype of this approach. Both patients and an experimental flow phantom were used to test the validity of this concept. Clinically, thrombosis was seen to persist as isointense or highly intense signal in the vascular lumina with the specialized sequence, while flow-related artifacts were replaced by hypointense signal, but not by signal void. These same changes were examined both quantitatively and qualitatively in the flow phantom by using varying velocities of flow. Although our clinical investigation concerns suspected dural sinus thrombosis, the principles of these specialized spin-echo techniques can be applied successfully throughout the head to eliminate certain flow-related artifacts.

Differentiation between meningeal fibrosis and chronic subdural hematoma after ventricular shunting: value of enhanced CT and MR scans.

Unenhanced CT in four patients with long-standing ventricular shunts demonstrated bilateral low-density extraaxial collections that were indistinguishable from chronic subdural hematomas. After administration of contrast material, however, there was marked enhancement of the collections as well as prominent paratentorial and parafalcial enhancement. MR imaging, performed in three patients, demonstrated the extent and paradural location of the collections better than CT did, but, as with unenhanced CT, the collections could not be distinguished from chronic subdural hematomas. On follow-up CT and MR, there was no change in the size, enhancement, or intensity of the collections. Histologic examination of biopsies from two patients demonstrated fibrosis of the meninges characterized by granulation tissue and collagen deposition. Meningeal fibrosis is a rare postshunt phenomenon that may mimic chronic subdural hematoma on unenhanced CT and MR. Recognition of this entity is important, particularly if therapeutic intervention is being considered. Therefore, an enhanced CT or enhanced MR scan should be obtained in chronically shunted patients to differentiate between a drainable chronic subdural hematoma and meningeal fibrosis.

Large Virchow-Robin spaces: MR-clinical correlation.

High-field MR scans frequently show Virchow-Robin spaces, which conform to the path of the penetrating arteries as they enter either the basal ganglia or the cortical gray matter over the high convexities. A retrospective review of 816 MR scans was undertaken to determine the clinical significance and associations (if any) of this finding. The Virchow-Robin spaces were graded, as were the nonspecific white-matter lesions. The presence of atrophy, infarction, hydrocephalus, and miscellaneous disease was noted. Large Virchow-Robin spaces were identified in 314 cases. A study sample was created consisting of a positive group containing all the larger grade 2 and 3 Virchow-Robin spaces (67 patients) and a negative or control group of 109 randomly selected patients from the original 502 who did not have large Virchow-Robin spaces. The charts of this study sample were reviewed and the following patient variables were noted: age, gender, incidental white-matter lesions, infarction, dementia, hypertension, and atrophy. For each variable, the proportion of patients who were positive for that variable was calculated for each of the two groups and compared across groups by using a Fisher exact test. Multiple logistic regression analysis was used to determine whether any of these variables were jointly associated with being "positive" or "negative" for large Virchow-Robin spaces. Some variables were strongly associated with being positive for large Virchow-Robin spaces: age, hypertension, dementia, and incidental white-matter lesions. Logistic regression analysis revealed that when all of these variables are considered jointly, only age remains significant.(ABSTRACT TRUNCATED AT 250 WORDS)