An intracranial aspergilloma with low signal on T2-weighted images corresponding to iron accumulation.

We present a case of cerebral aspergillosis in an immunocompetent patient. The MRI signal characteristics were compared with the histologic findings. Irregular low-signal zones were demonstrated between the wall of the abscess and the central necrosis on T2-weighted images; the pathology specimen revealed concentrated iron in these transitional zones but no hemosiderin. Iron is an essential element for the growth of fungal hyphae. The low-signal zones may represent the areas where there was active proliferation of aspergillus, and the unique location of the low signal may be a helpful imaging characteristic for the diagnosis of an aspergillus abscess.

Temporal lobe injury in temporal bone fractures.

OBJECTIVE: To determine the incidence of intracranial injury, specifically in the temporal lobe, in patients with longitudinal fractures of the temporal bone. DESIGN: Prospective inception cohort. SETTING: University of Maryland Division of Otolaryngology-Head and Neck Surgery and the Maryland Shock Trauma Center, Baltimore. PATIENTS: Twenty-seven consecutive patients with unilateral or bilateral temporal bone fractures. MAIN OUTCOME MEASURES: Evaluation of temporal bone and intracranial trauma using computed tomography (CT) and magnetic resonance imaging (MRI). RESULTS: Of the 27 patients enrolled in the study, 12 had the complete battery of MRI, CT, and physical and audiological examinations. In all 12 patients, MRI demonstrated adjacent middle cranial fossa meningeal enhancement. Results of non-contrast-enhanced CT and MRI demonstrated ipsilateral temporal lobe contusions in 6 of the 13 fractures for an overall incidence of 46%. In addition, MRI demonstrated 4 cerebral contusions not seen in the results of non-contrast-enhanced CT. CONCLUSIONS: While high-resolution CT remains the criterion standard for evaluation of temporal bone fractures, MRI revealed a higher incidence of related temporal lobe injuries. Magnetic resonance imaging data may be valuable in preoperative evaluation of patients who require surgical intervention through a middle cranial fossa approach to document pre-existing injury and potential morbidity before retraction of the middle cranial fossa dura mater and temporal lobe.

Superior blowout fracture of the orbit: the blowup fracture.

We describe a patient who sustained a blowout fracture of the superior orbital roof without an orbital rim fracture. The initial CT study (obtained with 10-mm-thick sections) did not show herniation of the intraorbital fat into the anterior cranial fossa; however, thin (3-mm-thick) direct orbital sections showed a fracture of the midportion of the superomedial orbital roof with displacement of the fracture fragment into the anterior cranial fossa.

Radiologic and pathologic findings of intracerebral schwannoma.

We report the radiologic and pathologic findings of an intracerebral schwannoma. MR imaging studies showed a superficially located cystic mass with an enhancing nodule and evidence of peritumoral edema or gliosis.

Subdural grid implantation for intracranial EEG recording: CT and MR appearance.

PURPOSE: Subdural grid arrays are used when seizure activity cannot be located by ictal scalp recordings and when functional cortical mapping is required before surgery. This study was performed to determine and compare the CT and MR imaging appearance of subdural EEG grids and to identify the types and frequency of associated complications. METHODS: We retrospectively reviewed the medical records and imaging studies of 51 consecutive patients who underwent 54 craniotomies for subdural EEG grid implantation with either stainless steel or platinum alloy contacts between June 1988 and September 1993. Twenty-two patients had both CT and MR examinations, 27 patients had CT only, and five patients had MR imaging only. All studies were assessed for image quality and degradation by the implanted EEG grids, for intra- and extraaxial collections, and for mass effect, with differences of opinion resolved by consensus. RESULTS: Subdural EEG grids caused extensive streak artifacts on all CT scans (corresponding directly to grid composition) and mild to moderate magnetic susceptibility artifacts on MR images. Sixteen associated complications were detected among the 54 patients imaged, including four significant extraaxial hematomas, four subfalcine or transtentorial herniations, two tension pneumocephali, two extraaxial CSF collections, two intraparenchymal hemorrhages, and one case each of cerebritis and brain abscess. In all but four cases, the detected complications were not clinically apparent and did not require specific treatment. There were no residual sequelae. CONCLUSION: Because of extensive streak artifacts, CT showed only gross complications, such as herniation and grid displacement by extraaxial collections. MR imaging artifacts were more localized, allowing superior evaluation of subdural EEG grid placement and associated complications.

Pre- and postoperative imaging analysis for frontal sinus disease following conservative partial middle turbinate resection.

The prudence of partial or complete middle turbinate resection during endoscopic sinus surgery (ESS) is controversial. The greatest concern regarding partial resection relates to the effect on the frontal recess and the development of frontal sinus disease. The purpose of this study was to radiographically evaluate the frontal sinus in patients who had undergone ESS with partial conservative middle turbinate resection. We reviewed the charts and operative records from 195 consecutive cases of ESS performed by a single surgeon (JFB) over a two-year period. Thirty-three of 117 patients who had undergone ESS with conservative partial middle turbinate resection without frontal recess exploration agreed to return for magnetic resonance imaging (MRI) of their sinuses. The preoperative computed tomography (CT) scans and postoperative MR images were reviewed and graded (1-3) by a single neuroradiologist. Significant frontal sinus disease (grades 2 and 3) was seen in 15 of 52 sides preoperatively (29%), and in 14 sides postoperatively (27%). During the postoperative MRI studies, only six frontal sinus sides demonstrated minimal mucosal thickening (grade 1) which had not been apparent on preoperative CT. This radiographic analysis suggests that conservative partial middle turbinate resection during ESS does not adversely affect the frontal sinus. We believe that the surgical technique employed when resecting the middle turbinate, and the avoidance of unnecessary dissection in the recess are both important factors in preventing the development of frontal sinus disease following ESS.

Systemic sarcoidosis with bilateral orbital involvement: MR findings.

A 43-year-old woman with diplopia had a disconjugate gaze on physical examination. MR images revealed enlarged, abnormally enhancing extraocular muscles and lacrimal glands bilaterally. Biopsy results were consistent with sarcoidosis. Chest radiographs and CT scans were normal. Clinical and MR findings improved after appropriate medical therapy.

Neurodevelopmental/neuroradiologic recovery of a child infected with HIV after treatment with combination antiretroviral therapy using the HIV-specific protease inhibitor ritonavir.

BACKGROUND: Neurodevelopmental impairment has been identified in children infected with human immunodeficiency virus (HIV). The frequency and spectrum of neurologic impairment are greater in children than those reported for adults. In children, HIV is known to enter the central nervous system early in the course of the disease. The presentation of pediatric neuro-acquired immune deficiency syndrome ranges from static (eg, nonprogressive developmental delay) to progressive encephalopathy (eg, acquired microcephaly, pyramidal tract signs, and spasticity). It has been demonstrated that antiretroviral agents can improve or even reverse the course of neurologic impairment in children. These changes have been attributed to various degrees of central nervous system drug penetration. Increasingly, protease inhibitors and combination antiretroviral therapy using reverse transcriptase inhibitors are being used in the treatment of children infected with HIV. The addition of a protease inhibitor to nucleoside analogue therapy has been reported to delay disease progression and prolong life in adults with moderate to advanced HIV disease. No data currently exist on the impact of combination therapy using two nucleoside analogues and a protease inhibitor on neurodevelopmental and neurologic function in children with HIV infection. The following case report presents the effects of combination therapy using ritonavir in a child infected with HIV. CASE REPORT: An 8-year, 2-month-old African-American boy was infected with HIV through vertical transmission. Regular monitoring of the patient's neurodevelopmental status has been conducted as part of his participation in longitudinal research protocols. For the first 51/2 years of life, his neurodevelopmental status was normal, with cognitive functioning as measured by standardized psychometric tools solidly in the average range. Speech and language skills were age-appropriate. Tests of gross and fine motor functioning as well as evaluation of overall neurodevelopmental status suggested normal development. Magnetic resonance imaging (MRI) of the brain was consistently normal. His family reported that adaptive functioning, peer and family relationships, and behavior were all within normal limits. School reports indicated consistently that the patient was performing at age and grade level, with respect to both academic achievement and behavior. Initial concerns regarding the patient's development were expressed by both his family and school at age 6 years, 6 months. These concerns included difficulty with classroom work, decreased attention, word-finding problems, fatigue, staring spells, and loss of strength. His family and school reported a marked loss of skills acquired previously. Results of formal psychological and speech and language evaluation reflected statistically significant drops in test scores from baseline, with both delayed and atypical skills evident. The patient's condition worsened rapidly. Within a few months, he was no longer able to use sentences to communicate. Cognitive testing was attempted, but he was unable to participate because of significant fatigue, limited attention, and inability to communicate verbally. His family described periods of disorientation and confusion, lethargy, and disinterest in age-appropriate activities. He became agitated and overstimulated easily both in small group settings and in crowds. He demonstrated both fine and gross motor impairments. When frustrated, he displayed infantile and autistic-like behavior. MRI with contrast showed diffuse atrophy as well as mild prominence of the ventricles and sulcii compared with baseline assessment. In addition to fatigue and neurologic symptoms, wasting syndrome was diagnosed, with loss of percentiles in both weight and height by age 71/2 years. Low-grade elevation of liver function tests and amylase was noted. Blood cultures for mycobacteria were negative, as were serologic tests for hepatitis. (ABSTRACT TRUN

Rhombencephalitis caused by adenovirus: MR imaging appearance.

Encephalitis is a rare manifestation of adenovirus infection. We report the MR imaging findings of a patient with rhombencephalitis caused by adenovirus. Imaging findings included T2 signal abnormalities in the brain stem and cerebellum with mild patchy enhancement and mass effect.

Concurrence of multiple sclerosis and brain tumor: clinical considerations.

We report a patient with multiple sclerosis (MS) who developed an oligodendroglioma 8 years after the initial diagnosis of MS. This is the first description of a neoplasm, suspected initially on brain MRI and subsequently confirmed by brain biopsy, in an MS patient. Our case emphasizes the need to evaluate atypical brain MRI lesions carefully, even in well-established MS patients, as well as to obtain a tissue diagnosis of such lesions whenever possible in order to determine their precise etiology.

Reversible empty sella in idiopathic intracranial hypertension: an indicator of successful therapy?

Idiopathic intracranial hypertension is commonly associated with an empty sella, caused by herniation of subarachnoid cerebrospinal fluid through an absent or patulous diaphragma sellae. We describe the findings in two patients who presented with headache, papilledema, and visual disturbances. Diagnosis of idiopathic intracranial hypertension was made on the basis of clinical symptoms and laboratory data. Initial imaging studies in each patient showed an empty sella. After treatment, one with acetazolamide and the other with lumboperitoneal shunting, the appearance of the sellar contents became normal.

Spinal epidural venous plexus: its MR enhancement patterns and their clinical significance.

OBJECTIVE: Evaluation of the clinical utility of enhancement of the spinal epidural venous plexus (SEVP) on postcontrast MR imaging. MATERIALS AND METHODS: The SEVP on pre- and postcontrast T1-weighted sagittal and axial MR images were evaluated in 188 patients whose MR findings were abnormal (positive group), in 223 patients with normal MR (negative group), and in 35 volunteers. The enhancement patterns of the SEVP were graded 1 to 4 according to their degree of dilation. These three groups were compared and analyzed. RESULTS: Epidural and intradural lesions in the positive group showed higher grades of epidural vein enhancement compared with the negative group (p = 0.01). Epidural abscesses and epidural metastases frequently showed moderate to marked dilatation of the SEVP. Degenerative disk disease with stenosis of the spinal canal exhibited more localized patterns of dilation. Most intradural lesions with cord swelling demonstrated dilation of the SEVP. Visualization of the SEVP did not differ statistically between bone and soft tissue lesions in the positive group and the negative group (p = 0.13). Evaluation of follow-up examinations showed that changes in SEVP grades were indicative of changes in disease. CONCLUSION: SEVP enhancement patterns assist in the evaluation of disease in the spinal canal and will help to differentiate normal from pathological conditions.

MR of optic papilla protrusion in patients with high intracranial pressure.

PURPOSE: To evaluate the signal characteristics of the optic papilla (optic nerve head) on routine cranial MR images in patients with clinical evidence of optic papilla elevation caused by high intracranial pressure, and to compare these findings with findings in healthy adult volunteers. METHODS: We reviewed retropectively the MR imaging examinations of 15 patients who were referred with objectively decreased visual acuity and funduscopic findings of optic papilla elevation. T1-weighted and T2-weighted axial MR images were obtained by using conventional spinecho acquisitions on 1.5-T MR imagers. In addition, the MR imaging studies in 10 healthy adult volunteers without visual impairment were reviewed as controls. RESULTS: In 10 (67%) of the 15 patients, visual elevation of the optic papilla was shown by MR imaging. In all 15 patients, the MR signal intensity of the optic papilla was hypointense relative to the vitreous of the globe on T2-weighted images. In the healthy volunteer group, the optic papillae were all similarly hypointense relative to the vitreous of the globe on T2-weighted images; however, these optic papillae were flat. CONCLUSION: Clinical examination and MR imaging may show elevation of the optic papilla in patients with high intracranial pressure. When chronic, optic papilla elevation has been shown to correlate well with severe loss of vision. Actual edema of the optic papilla seems to play little role in the physical elevation observed clinically in the chronic stages of this pathologic process.

Detection of vasospasm by transcranial Doppler sonography. The challenges of the anterior and posterior cerebral arteries.

Little information exists on the utility of transcranial Doppler sonography (TCD) in detecting anterior (ACA) and posterior cerebral artery (PCA) vasospasm following subarachnoid hemorrhage. During the period at risk for vasospasm, 53 patients with subarachnoid hemorrhage who had technically adequate TCD performed within 24 hours of cerebral angiography, allowing evaluation of 87 ACAs and 84 PCAs, were studied. ACA and PCA vasospasm were defined by mean blood flow velocities of at least 120 cm/sec and at least 90 cm/sec, respectively. For detection of ACA vasospasm, sensitivity was 18% and specificity was 65%. For PCA vasospasm, sensitivity was 48% and specificity was 69%. False-positive findings for occlusion accounted for 12 (92%) of 13 ACA of false-positive results and 7 (37%) of 19 PCA false-positive results, and were most often due to anatomical factors and operator error or inexperience. After exclusion of both true-positive and false-positive findings for occlusion and changes in the diagnostic criterion to at least 130 cm/sec for ACA vasospasm and at least 110 cm/sec for PCA vasospasm, specificity improved for both types of vasospasms (100 and 93%, respectively). However, the sensitivity of TCD to detect ACA and PCA vasospasm is limited by a variety of anatomical, technical, and other factors. It is concluded that TCD is highly specific in detecting both ACA and PCA vasospasm on arteries that can be insonated.

Radiosurgery for cerebral arteriovenous malformations: assessment of early phase magnetic resonance imaging and significance of gadolinium-DTPA enhancement.

PURPOSE: To evaluate the initial changes within the nidus of arteriovenous malformations (AVMs) and to assess the reaction to the brain tissue surrounding AVMs after radiosurgery by serial magnetic resonance (MR) imaging. METHODS AND MATERIALS: Twenty-one patients, treated using 60Co gamma knife unit with cerebral AVMs, were retrospectively evaluated. Forty-seven follow-up MR images of the 21 patients were performed including 10 patients with two or more serial gadolinium enhanced studies (Gd-MR). Two or more sequential MR angiographies (MRA) were obtained in 13 patients. Three-dimensional (3D) time-of-flight MRA and two-dimensional (2D) phase contrast MRA were used in 13 patients for evaluating the flow changes of AVMs. The follow-up period after radiosurgery ranged from 3 to 30 months (average 10.8 months) and the interval time of MRI ranged from 34 days to 13 months (average 4.9 months). RESULTS: Reduction of nidus size was observed in 14 of 21 patients (67%) between 4 to 13 months on spin echo (SE) images. Complete obliteration was observed on SE images in 4 of these 14 patients; three were confirmed by conventional angiography. New hyperintense areas surrounding the nidus on T2s-weighted images (T2WI) developed in 9 of the 14 patients who showed nidus reduction between 5 to 17 months after radiosurgery; in three patients, size of the hyperintense area started to decrease between 6 to 7 months after its appearance. Probable radiation necrosis of pons developed in one patient 26 months after radiosurgery. The irradiated area within the AVM nidus was significantly enhanced in 8 of the 10 patients who underwent Gd-MR. The degrees of enhancement within the nidus increased with time in 7 of the 10 patients. Overall, total enhancement of irradiated areas was observed in four of the 10 patients; in three of the four, the enhancement decreased in size and degree, indicating nidus reduction. In three patients who had a partial volume irradiation within the nidus, the enhancing areas corresponded with the exact portions of irradiated volume. The nidus reduction was observed in 7 of the 13 patients on MRA during 5 to 13 months after radiosurgery. MRA was more useful compared to SE images in four of the seven patients in evaluating the size change of AVM nidus, feeding arteries, and draining veins. CONCLUSION: Magnetic resonance imaging and MRA were useful in assessing the progress of nidus reduction. T2-weighted imaging was sensitive to radiation-induced reaction in and around the AVM nidus. The enhancement within the AVM nidus on Gd-MR may represent the initial sign of nidus reduction and demonstrates the exact location of irradiation in the nidus. The changes of the enhancement pattern are presumed to represent the processes of nidus reduction and irradiated reaction within the AVM nidus.

Detection of intracranial internal carotid artery and middle cerebral artery vasospasm following subarachnoid hemorrhage.

Little is known about the accuracy of transcranial Doppler (TCD) sonography in detecting intracranial internal carotid artery (IICA) and middle cerebral artery (MCA) vasospasm. TCD was performed in 49 patients with subarachnoid hemorrhage to evaluate 90 IICAs and 87 MCAs during the vasospasm period. When a mean velocity of at least 90 cm/sec was used to indicate IICA vasospasm, there were 11 positive, 42 negative, 4 false-positive, and 33 false-negative results. Sensitivity was 25% and specificity was 93%. When a mean velocity of at least 120 cm/sec was used to indicate MCA vasospasm, there were 15 positive, 45 negative, 3 false-positive, and 24 false-negative results (15 operator errors). Sensitivity was 38.5% and specificity was 93.7%. When the diagnostic criterion was changed to at least 130 cm/sec, specificities were 100% (IICA) and 96% (MCA) and positive predictive values were 100% (IICA) and 87% (MCA). The authors conclude that TCD accurately detects IICA and MCA vasospasm when flow velocities are at least 130 cm/sec. However, its sensitivity may be underestimated and the importance of operator error, overestimated.

Radiologic appearance of the dysembryoplastic neuroepithelial tumor.

PURPOSE: To evaluate the computed tomographic (CT) and magnetic resonance (MR) imaging features of dysembryoplastic neuroepithelial tumor (DNT). MATERIALS AND METHODS: Six CT studies (four with contrast material enhancement) and 10 MR imaging studies (seven with gadolinium enhancement) obtained in 10 patients with a history of seizures and pathologically proved DNT were retrospectively reviewed. RESULTS: All tumors were intracortical or subcortical. CT showed a low-attenuation mass in all cases except one of mixed isoattenuation and low attenuation. The DNT had decreased signal intensity on T1-weighted MR images and well-demarcated increased signal intensity on T2-weighted images without peritumoral edema. Prominent MR imaging features were a gyriform configuration on T1- or T2-weighted images in 10 patients (100%), well-demarcated lobular tumor margins on T2-weighted images in eight (80%), and a high rate of bone remodeling of the adjacent calvaria on MR (60% [n = 6]) and CT (67% [n = 4]) images. CONCLUSION: Diagnosis of DNT with imaging modalities alone may be difficult, but these radiologic features may aid in differentiating DNT from other gliomas.

Posterior fossa glioblastoma multiforme: MR findings.

PURPOSE: To characterize the MR findings of glioblastoma multiforme in the posterior fossa. METHODS: MR studies of nine patients with surgically proved posterior fossa glioblastoma multiforme were retrospectively evaluated. MR characteristics studied included tumor location, signal intensity, enhancement pattern, and presence of intratumoral hemorrhage, as well as presence of secondary hydrocephalus or metastatic spread. RESULTS: The tumors were located in the median portion of the cerebellum or brain stem in eight cases. Six extended into the fourth ventricle. Hydrocephalus was seen in four cases. Six cases demonstrated decreased T1- and increased T2-weighted signal intensities. Three cases demonstrated mixed signal intensities suggesting intratumoral hemorrhage. All of the eight patients who received contrast showed moderate to marked heterogeneous ringlike enhancement suggesting intratumoral necrosis. Multicentric/multifocal lesions or extraaxial metastases were identified in three of the nine cases, and there was extracranial extension into the cervical region in one case. CONCLUSION: Glioblastoma multiforme is a rare tumor in the posterior fossa. Differentiating it from metastatic tumor or malignant astrocytoma was difficult. However, combination of heterogeneous and ringlike enhancement, midline location, poorly defined margin, tumoral hemorrhage, concomitant multicentric/multifocal lesions, and extraaxial or extracranial metastasis may be clues for the prospective diagnosis of glioblastoma multiforme.

Transcranial Doppler detection of vertebrobasilar vasospasm following subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Transcranial Doppler sonography is of established value in the detection and monitoring of middle cerebral artery vasospasm. Little information exists on the utility of transcranial Doppler for detection of posterior circulation vasospasm. METHODS: Cerebral angiography and conventional hand-held transcranial Doppler sonography were compared to determine sensitivity and specificity of transcranial Doppler for detection of vertebral and basilar artery vasospasm. RESULTS: Of 59 consecutive subarachnoid hemorrhage patients with transcranial Doppler angiogram correlations, 42 underwent posterior circulation angiography to evaluate 64 vertebral arteries and 42 basilar arteries during the period of risk for vasospasm and had technically adequate transcranial Doppler examinations within 24 hours of the angiogram. A mean flow velocity of 60 cm/s and above was indicative of both vertebral and basilar artery vasospasm. For the vertebral artery, there were 7 true-positive test results, 42 true-negatives, 6 false-positives (unknown cause in 3, increased collateral flow in 1, adjacent vessel vasospasm in 1, hyperperfusion in 1), and 9 false-negatives (anatomic in 7, operator error in 2). Sensitivity was 44% and specificity was 87.5%. For the basilar artery, there were 10 true-positives, 23 true-negatives, 6 false-positives (unknown cause in 4, hyperemia/hyperperfusion in 1, increased collateral flow in 1), and 3 false-negatives (operator error in 2, tortuous vessel course in 1). Sensitivity was 76.9% and specificity was 79.3%. When the diagnostic criterion was changed to > or = 80 cm/s (vertebral artery) and > or = 95 cm/s (basilar artery), all false-positive results were eliminated (specificity and positive predictive value, 100%). CONCLUSIONS: Our data suggest that transcranial Doppler has good specificity for the detection of vertebral artery vasospasm and good sensitivity and specificity for the detection of basilar artery vasospasm. Transcranial Doppler is highly specific (100%) for vertebral and basilar artery vasospasm when flow velocities are > or = 80 and > or = 95 cm/s, respectively.