Central Nervous System and Head and Neck Histiocytoses: A Comprehensive Review on the Spectrum of Imaging Findings.

The histiocytoses are a rare group of varied but related disorders characterized by abnormal tissue proliferation of macrophages and dendritic cells within tissues. The purpose of this article was to review the imaging findings in patients presenting with CNS and with head and neck manifestations of these disorders. Histiocytoses include but are not limited to Rosai-Dorfman disease, Erdheim Chester disease, Langerhans cell histiocytosis, histiocytic sarcoma, and juvenile xanthogranuloma. A review of the literature was performed to determine the sites of disease involvement. This article includes the demographics, histopathologic criteria for diagnosis, and imaging features of these histiocytoses, and describes the manifestations in locations known to harbor disease: intraaxial and extra-axial intracranial regions, the calvaria, skull base, hypothalamopituitary axis, orbits, paranasal sinuses, spine, and the head and neck region. Histiocytoses have variable imaging appearances in the CNS and in the head and neck region, and radiologists should be aware of the spectrum of findings to avoid mistaking them for other disease processes. LEARNING OBJECTIVE: To understand the general pathophysiology, clinical presentation, and typical imaging characteristics of the most common histiocytoses; comprehend the morphologic and immunohistochemical characteristics of these histiocytoses and the hallmark findings on pathology; and be able to differentiate between these disorders based on their most common presentations.

Dynamic contrast-enhanced perfusion processing for neuroradiologists: model-dependent analysis may not be necessary for determining recurrent high-grade glioma versus treatment effect.

BACKGROUND AND PURPOSE: Dynamic contrast-enhanced perfusion MR imaging has proved useful in determining whether a contrast-enhancing lesion is secondary to recurrent glial tumor or is treatment-related. In this article, we explore the best method for dynamic contrast-enhanced data analysis. MATERIALS AND METHODS: We retrospectively reviewed 24 patients who met the following conditions: 1) had at least an initial treatment of a glioma, 2) underwent a half-dose contrast agent (0.05-mmol/kg) diagnostic-quality dynamic contrast-enhanced perfusion study for an enhancing lesion, and 3) had a diagnosis by pathology within 30 days of imaging. The dynamic contrast-enhanced data were processed by using model-dependent analysis (nordicICE) using a 2-compartment model and model-independent signal intensity with time. Multiple methods of determining the vascular input function and numerous perfusion parameters were tested in comparison with a pathologic diagnosis. RESULTS: The best accuracy (88%) with good correlation compared with pathology (P = .005) was obtained by using a novel, model-independent signal-intensity measurement derived from a brief integration beginning after the initial washout and by using the vascular input function from the superior sagittal sinus for normalization. Modeled parameters, such as mean endothelial transfer constant > 0.05 minutes(-1), correlated (P = .002) but did not reach a diagnostic accuracy equivalent to the model-independent parameter. CONCLUSIONS: A novel model-independent dynamic contrast-enhanced analysis method showed diagnostic equivalency to more complex model-dependent methods. Having a brief integration after the first pass of contrast may diminish the effects of partial volume macroscopic vessels and slow progressive enhancement characteristic of necrosis. The simple modeling is technique- and observer-dependent but is less time-consuming.

Computerized tomography for diagnosis of supratentorial tumors.

The brains of 1851 patients were examined with 160 X 160 matrix computed tomography (CT) during a period of nine months. The CT patterns of 90 supratentorial tumors (excluding sellar tumors) were reviewed. A great variety of CT patterns were found with glioblastomas, the most typical being a tumor with mixed absorption values. Astrocytomas appeared as low-density lesions. The characteristic appearance for meningiomas was a homogeneous density, with an obvious increase in density after contrast injection. Metastases appeared as low- or high-density lesions with marked edema surrounding the tumor. Some minor groups such as craniopharyngiomas, epidermoid tumors and pineal tumors were described. The lesion was detected in 94% and a correct diagnosis was made in 92% of cases.

Manic syndrome in AIDS.

A manic syndrome in eight patients with AIDS is described. On the basis of clinical, neuropsychological, laboratory, magnetic resonance imaging, and epidemiological evidence, the authors suggest that the manic syndrome was secondary to HIV infection. The patients also developed concomitant cognitive impairment.

Opportunistic cerebral vasculopathy and stroke in patients with the acquired immunodeficiency syndrome.

OBJECTIVE: To describe an unusual cause of stroke in patients with the acquired immunodeficiency syndrome. DESIGN: An observational case series of hospitalized patients with subsequent autopsy. MEASURES: Clinical, radiological, and pathological examinations were performed. RESULTS: In three of 14 patients with stroke, the infarctions were secondary to an opportunistic vasculopathy caused by Candida albicans, cytomegalovirus, or lymphoma. CONCLUSION: Opportunistic conditions may lead to vascular abnormalities and subsequent stroke in patients with the acquired immunodeficiency syndrome.

Acute cerebellar hemorrhage secondary to capillary telangiectasia in an infant. A case report.

We encountered an unusual case of an acute cerebellar hemorrhage secondary to a capillary telangiectasia in a 4-month-old infant. Prompt surgical evacuation of the cerebellar hematoma resulted in an excellent neurologic outcome. To the best of our knowledge, ours represents the only clinical case report of massive cerebellar bleed due to a capillary telangiectasia.

Magnetic resonance imaging findings in HIV cognitive impairment.

Atrophy and white matter changes seen on magnetic resonance imaging scans have been observed in association with the acquired immunodeficiency syndrome dementia complex, but these appear to be late findings relative to clinical expression. We report a new magnetic resonance imaging observation in patients with early cognitive impairment due to human immunodeficiency virus infection. Fifty-two patients had a total of 86 magnetic resonance imaging scans during the study period. All scans were obtained with a 1.5-T system. The proton density spin echo (repetition time of 2000 milliseconds and echo delay time of 30 milliseconds) study demonstrated high-signal lesions in the region of the splenium of the corpus callosum and in the crura of the fornices. The lesions demonstrated no contrast enhancement with gadopentate dimeglumine. Pathological examination was performed in five patients. The fornix-subcallosal abnormality may be related to the memory dysfunction in patients with human immunodeficiency virus-related cognitive impairment.

Herpes simplex virus encephalitis: new diagnostic and clinical features and results of therapy.

Six patients with herpes simplex virus (HSV) encephalitis underwent diagnostic and clinical evaluation. The HSV or its antigenic material was found in three brain biopsy specimens. In the remaining three cases, the diagnosis was supported by detection of HSV antibodies in the CSF. Cell count and total protein concentration in the CSF reached a maximum level at three weeks and two months, respectively. The IgG index and HSV antibody level in the CSF often remained constant after reaching maximal values. In three patients, a transient low serum sodium level was observed. Characteristic EEG changes were present five to 11 days after the onset of symptoms. Computerized tomographic scanning revealed a temporal low-density lesion. Three patients became deeply comatose and had respiratory failure. The patient without vidarabine therapy and one of the five patients treated with vidarabine died.

Cognitive performance and regional brain volume in human immunodeficiency virus type 1 infection.

BACKGROUND: Brain atrophy has been reported to occur in advancing human immunodeficiency virus (HIV) infection, particularly in patients with HIV-related dementia. Atrophy of the caudate region, as assessed by magnetic resonance imaging measures, has been reported to correlate with cognitive impairment in patients with HIV infection; however, differences in the severity of HIV-induced immunosuppression may have contributed to these findings. OBJECTIVE: To determine the relationship between regional brain volumes and cognitive performance in individuals with HIV infection. PATIENTS AND METHODS: We evaluated 11 patients with advanced HIV disease by using neuropsychologic tests and quantitative magnetic resonance imaging volume analysis. SETTING: University hospital, involving patients from a clinical trial. RESULTS: Caudate volume, expressed as a ratio of total intracranial volume, correlated with performance on the Trails A and Grooved Pegboard tests, but not with other tests of memory, motor speed, or mood (adjusted for age and education). Hippocampal volume did not correlate with any of the neuropsychologic tests. CONCLUSIONS: Caudate volume in patients with advanced HIV disease is associated with poor performance on neuropsychologic tests of complex motor and sequencing skills. Hippocampal volume does not appear to be related to impairment on neuropsychologic tests. These findings are independent of the degree of immunosuppression and the overall extent of brain atrophy; however, these results must be interpreted with some caution, given the limited sample size.

Genetic susceptibility to multiple sclerosis. A co-twin study of a nationwide series.

The problems of differentiation between environmental and genetic influences on the development of multiple sclerosis are well known. Twin studies may provide valuable information on this question. However, most published twin series are selected and no through clinical twin studies based on epidemiologic series have been carried out. In this study, all available same-sex twin pairs with clinically definite multiple sclerosis derived from the Finnish Twin Cohort of 15815 pairs were studied by clinical evaluation, magnetic resonance imaging, and visual and auditory evoked responses. The mean length of follow-up of the pairs after the onset of symptoms of multiple sclerosis was 20 years. Two of the seven monozygotic pairs were concordant; one was definitely so, and in the other, the co-twin of the index case had, in addition to clinical findings, white matter changes suggestive of multiple sclerosis in magnetic resonance imaging and abnormal visual evoked responses. All six dizygotic pairs were discordant. The frequency of the HLA antigen DR2 in probands (69%) was significantly increased, but the distribution among the healthy subjects and patients showed nonsignificant differences. The results indicate a genetic influence on the susceptibility to multiple sclerosis, although still unknown genetic determinants are possible involved.

Clinical evaluation of stenosis of the carotid bifurcation with magnetic resonance angiographic techniques.

We evaluated the images of 60 carotid artery bifurcations in 31 patients suspected to have carotid artery disease who underwent invasive carotid angiography and combined two-dimensional, phase-sensitive and a gradient-echo magnetic resonance angiography. The phase scans consisted of seven serial projections that were obtained at 20 degrees intervals (11.0 minutes) around the carotid bifurcation; the gradient-echo (GRASS) scans were composed of 11 axial images (2.4 minutes) acquired through the bifurcation. The two magnetic resonance angiographic techniques yielded complementary pieces of information and were used together to compare magnetic resonance angiography with invasive angiography. Comparison of magnetic resonance and invasive angiograms of the 60 carotid arteries shows that the sensitivity (86%) and specificity (92%) of the magnetic resonance angiographic techniques we used to diagnose clinically significant carotid stenosis approach but do not reach those of invasive angiography.

Herpes simplex virus encephalitis: progression of lesion shown by CT.

Computed tomography (CT) of six patients with herpes simplex virus encephalitis (HSVE) showed a deep temporal low attenuation with patchy enhancement after contrast injection in the acute phase of the disease. The involvement progressed in all surviving patients, all of whom were treated with adenine arabinoside.

Efficacy of gadolinium in MR brain imaging of HIV-infected patients.

PURPOSE: To determine the value of gadolinium in routine head MR imaging of HIV-infected patients. METHODS: One hundred and three consecutive human immunodeficiency virus-infected patients referred for head MR imaging were scanned without and with intravenous gadopentetate dimeglumine (Gd-DTPA) contrast. RESULTS: The precontrast scans of 82 patients were either normal, or had atrophy or diffuse white matter changes only. Sixteen of these 82 demonstrated enhancing abnormalities: eight meningeal/ependymal enhancement and eight focal enhancing lesions. Twenty-one of the 103 scans had focal or mass lesions on the precontrast images; in eight of these scans, new information was obtained with Gd-DTPA. Of the 24 patients in both groups where new information was obtained with Gd-DTPA, the information contributed to a change in the clinical care of nine patients. CONCLUSION: Gadolinium-enhanced MR is useful in the management of selected patients with human immunodeficiency virus infection, for example those with symptoms suggesting meningeal involvement, focal brain lesions, or if the unenhanced MR does not explain all the patient's symptoms.

Infantile-onset spinocerebellar ataxia: MR and CT findings.

PURPOSE: To report the MR and CT findings in a hereditary disease, infantile-onset spinocerebellar ataxia (IOSCA). METHODS: We studied the brains of 17 patients with infantile-onset spinocerebellar ataxia with CT and/or MR to determine the presence of cerebellar and brain stem atrophy and parenchymal lesions. RESULTS: Cerebellar cortical atrophy was seen in 13 patients. The degree of atrophy correlated with increasing age and clinical deterioration. Brain stem atrophy was seen in 8 patients. It was never severe, and the basis pontis was not flattened even in the most severe cases. Hyperintense lesions were noted within the white matter of cerebellum, in the dentate nuclei, and in the middle cerebellar peduncles in 3 patients. The upper cervical cord was seen in 9 patients and showed mild to moderate atrophy in 4. The basal ganglia and cerebral hemispheres were normal, except in 2 patients transient cortical and subcortical lesions developed during episodes of status epilepticus; mild cortical brain atrophy subsequently developed. CONCLUSION: The brain MR and CT findings of patients with infantile-onset spinocerebellar ataxia correspond to the neuropathologic entities of cerebellar cortical atrophy, olivopontocerebellar atrophy, and spinocerebellar atrophy. The appearance of the findings followed a uniform time sequence from cerebellar cortical atrophy in the early stage of the disease to olivopontocerebellar atrophy and spinocerebellar atrophy in the later stage. The severity of atrophy correlated with clinical deterioration.

Neuroradiologic findings in children with mitochondrial disorders.

PURPOSE: We report the neuroradiologic findings in 25 children with various mitochondrial diseases. METHODS: Twenty-two children with a mitochondrial disorder had MR imaging of the brain and three children had CT studies. In all cases, the diagnosis was based on examination of muscle morphology, analysis of oxygen consumption and respiratory chain enzyme activity in isolated muscle mitochondria, and analysis of rearrangements of the mitochondrial DNA. RESULTS: Fifteen patients were found to have the classical syndromes of mitochondrial diseases. Four children had Kearns-Sayre syndrome, but only one had the typical neuroradiologic findings of basal ganglia and brain stem lesions, T2 hyperintensity of the cerebral white matter, and cerebellar atrophy; the others had nonspecific or normal findings. Eight patients had Leigh syndrome, and all showed changes in the putamina. Involvement of the caudate nuclei, globus pallidi, thalami, and brain stem was common, and diffuse supratentorial white matter T2 hyperintensity was seen in two of these patients. Three patients had mitochondrial encephalopathy with lactic acidosis and strokelike episodes (MELAS), with infarctlike lesions that did not correspond to the vascular territories. Ten children with complex I or IV deficiencies and abnormal muscle morphology had nonspecific imaging findings, such as atrophy and abnormal or delayed myelination. One patient with combined complex I and IV deficiency had extensive white matter changes. None of the patients with clinical encephalopathy had normal findings. CONCLUSION: MR imaging is helpful in the diagnosis of the classical mitochondrial diseases; however, nonspecific findings are common.

Duplication of the extracranial internal carotid artery.

We describe a case of duplication of the left internal carotid artery from a point 1 cm distal to the origin to the proximal petrous segment where the vessel reunites. Duplication and fenestration of the internal carotid artery are discussed. A review of embryologic development is presented. Identification of these entities is important, especially in patients who require surgical intervention involving the internal carotid artery.

A comparison of default and reduced bandwidth MR imaging of the spine at 1.5 T.

The value of a reduced bandwidth MR imaging technique was tested prospectively in 51 spinal MR examinations by using default (16 kHz) bandwidth, 2000/30, 90 (TR/TEs) and 600/30, and reduced (8 kHz) bandwidth, 2000/48, 92 and 600/30, techniques at 1.5 T. Bandwidth reduction was used to maintain the signal-to-noise ratio for a reduced scan time. Concerns have been raised as to the effect of bandwidth reduction at high field, since a savings in time or an increased signal-to-noise ratio occur at the expense of increased chemical shift misregistration artifact. However, when appreciable, the chemical shift-related artifact in the spine was typically located in the frequency-encoding direction at the vertebral body/disk space interface or the dural sac/epidural fat interface in the lower lumbosacral region and was easily distinguished from pathologic lesions. There were no missed diagnoses with the reduced bandwidth technique. This study suggests that chemical shift-related artifact will rarely be confused with pathology by an experienced reader and suggests a clinical role for the bandwidth technique to decrease scanning time in uncooperative patients or to allow acquisition of additional imaging planes in a reasonable time.

A follow-up study of very low field MRI findings and clinical course in multiple sclerosis.

Seventy-three consecutive patients with definite multiple sclerosis (MS) were examined with very low field (0.17 and 0.02 tesla) magnetic resonance imaging (MRI) of the brain. Fifty-seven patients were examined a second time after 6 months, 41 patients a third time after 1 year, and 25 patients a fourth time after 2 years. The initial finding was abnormal in 57/73 patients (78%). The number of lesions increased with age, duration of disease, and increasing disability. Plaques were more numerous in progressive than in remitting MS. Of the patients with abnormal MRI 65% had more than 3 lesions, and in 82% lesions were smaller than 2.5 cm in diameter. After follow-ups of 1 year and 2 years the size of MRI lesions remained unchanged in 55% and 64%, respectively. Unchanged plaque numbers were found in 72% and 60%. Unchanged MRI was most common among patients with remitting MS who were in a stable phase. Decrease in size and disappearance of plaques correlated well with clinical remissions. Increase in size was rare even during relapses. New plaques could appear during all phases of clinical course although they reflected better a relapse of remitting or progressive disease.

Low-field MRI in the evaluation of rheumatoid cervical spine. Comparison with neurological findings and routine plain radiography.

The usefulness of a low-field magnetic resonance imaging (MRI) instrument in the evaluation of cervical spine abnormalities was studied in 20 patients with rheumatoid arthritis and known anterior atlantoaxial subluxation (AAS) (16 patients) or other cervical spine abnormalities (4 patients). The MRI results were compared with routine plain radiographs and with neurological findings. Three patients had a clinical suspicion of cervical spinal cord compression. This was confirmed by MRI, which additionally detected one more patient with compressive myelopathy. Anterior AAS in MR images was seen in 4 patients, but proper flexion images were not obtained. Atlantoaxial impaction was detected by a recent method of Sakaguchi-Kauppi in 16 patients as compared to 9 patients by the McGregor method and 4 patients by MRI. Most of the clinically important consequences of rheumatoid cervical spine are seen with a low-field MR imager, but detailed bony changes and precise measurements are better evaluated with plain X-rays.

Wasp sting-associated cerebral infarction: a role for cerebrovascular sympathetic innervation.

A 38-year-old man, stung repeatedly by wasps on the left face and neck, had his left internal carotid artery occluded 2 days later. A mechanism for ischemic stroke involving the sympathetic innervation of cerebral vasculature is suggested.