Benign fibrous histiocytoma of the nasal cavity in a newborn: MR and CT findings.

Benign fibrous histiocytoma of the nasal cavity in a newborn is rare, and the MR imaging appearance of this entity has not been reported. We present the MR and CT findings in such a case and review the differential diagnosis for intranasal masses in the neonate.

Moyamoya disease in the United States.

The epidemiology and radiological features of Moyamoya disease (MMD) in the US were investigated. This study encompassed 98 cases; 26 were newly collected from eight US institutions and 72 were previously reported in the US literature. The patients ranged in age from 6 months to 67 years with age peaks in the first, third and fourth decades. MMD was seen in various ethnic groups and females were more commonly involved (71%) than males. A specific etiology could not be determined in most cases but arteriosclerosis and use of oral contraceptives were occasional associations. On angiography and/or magnetic resonance angiography (MRA), carotid arterial stenosis or occlusion was seen bilaterally in 95 cases (97%) and unilaterally in three. On MR or MRA, internal carotid steno-occlusive lesions were well demonstrated in all cases but Moyamoya collateral vessels (MMVs) were visualized in only 65% of the patients. MMVs in the basal ganglia and thalami were best demonstrated on T1 weighted images. Parenchymal lesions were seen in all patients and were often bilateral. With advances in MR techniques and increasing awareness of diagnostic guidelines, MMD will be diagnosed more frequently than before in the US.

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.

Vertebrobasilar dolichoectasia: assessment using MR.

We evaluated six patients with vertebrobasilar dolichoectasia (VBD) comparing clinical presentation with magnetic resonance (MR) and computed tomography (CT) imaging. MR diagnosed the condition as well as CT in all cases, but proved superior to CT in delineating the anatomical relationship of the vessels to the neural structures. MR proved especially useful in cases of VBD-associated hydrocephalus and posterior fossa masses. A coexisting tumor was diagnosed by MR in one case.

MR of the cauda equina.

To define the anatomy of the cauda equina nerve roots by MR imaging, the lower spine of 14 normal volunteers was imaged using a high-field surface-coil technique. A total of 56 sagittal and 56 axial MR sections (eight selected slices from each case) were correlated with undistorted anatomic sections from cadaver spine specimens, and the visualization of the nerve roots was assessed. In addition, MR images of three patients with infiltrating or seeding tumors affecting the cauda equina were analyzed. Seventy-eight percent of the MR sections from normal cases clearly showed the anatomy of the cauda equina nerve roots. The nerve roots were fairly shown in 17% of the sections; and false findings (presumably caused by CSF pulsation) were observed in the remaining 5%. Coronal imaging provided excellent anatomic views of the nerve roots within the intervertebral foramina. Morphologic alterations in the pathologic cases were correctly shown when both T1- and T2-weighted imaging were used. In conclusion, MR proved efficient in viewing the cauda equina region.

MR imaging of a spinal teratoma.

A benign intradural teratoma of the lumbar spine was studied with myelography, CT, magnetic resonance imaging, and histologic correlation. The tumor was composed of three portions (adipose tissue, neurofibrous tissue containing a large duct, and a keratinous cyst). Computed tomography distinguished the fat and the solid tissue from surrounding CSF but failed to differentiate the keratinous component of the mass. Magnetic resonance adequately demonstrated all three main components of the tumor.

Computed tomography of malignant lymphoma involving the skull.

The CT findings in two patients with the unusual presentation of malignant lymphoma in the skull are described. The dominant CT findings were contrast enhanced large soft tissue masses without calcifications on both sides of the bone with very little or no changes in the bone itself. This characteristic CT appearance may be helpful to differentiate primary lymphoma of the skull from other bone tumors and osteomyelitis.

Subdural tension pneumocephalus following surgery.

A clinical computed tomographic (CT) study of six patients, two with tension and four with benign postoperative subdural pneumocephalus, was done coupled with a data analysis of the literature. The mass effect of a tension subdural pneumatoma was demonstrable as shift in the midline structures when the air was unilateral, whereas an asymptomatic pneumocephalus showed no actual mass effect. Inspection of the digital lateral scout view studies usually provides a rough estimate of the magnitude of a pneumatoma; the volume of the air could be computed on the axial transverse CT scans. In a preliminary in vivo volume estimation, the subdural air measured more than 65 cm3 for the two symptomatic patients and less than 20 cm3 for the asymptomatic ones. Of 21 reported cases of postsurgical tension pneumocephalus, 18 (86%) had the pneumatoma in the subdural space. The predisposing neurosurgical conditions to tension pneumatoma included: (a) a preexisting open cerebrospinal fluid drainage device; (b) surgery on the posterior fossa in the sitting position; and (c) chronic subdural hematoma.

Patterns of edema in tumors vs. infarcts: visualization of white matter pathways.

The computed tomographic (CT) scans of 339 patients with recent nonhemorrhagic cerebral infarct and 155 patients with supratentorial tumors were reviewed to evaluate the appearance of cerebral edema. White matter pathway edema characterized the CT pattern in 106 (68%) of the 155 tumor cases. In these 106 cases, there were 143 tumors, with edema in the arcuate white matter (73%), the external capsule (33%), the internal capsule (12%) and the corpus callosum (14%). In contrast, only four of the 339 cases of infarct had edema in the white matter pathways. In addition, 260 (77%) of the infarct cases had edema in both gray and white matter and 98% had at least gray matter involvement, while only two of the tumor cases had any gray matter edema. White matter pathway involvement with respect to tumor site is useful in differentiating tumor and infarct edema.