Neuropathology for the neuroradiologist: fluorescence in situ hybridization.

SUMMARY: Fluorescence in situ hybridization is a molecular cytogenetic technique that localizes segments of DNA within tumor cells by using dyes that are visible with a fluorescent microscope. The technique has proved useful in typing a variety of tumors such as oligodendrogliomas and in understanding the genetic forces driving oncogenesis.

Neuropathology for the neuroradiologist: Antoni A and Antoni B tissue patterns.

Histologic patterns of cellular architecture often suggest a tissue diagnosis. Distinctive histologic patterns seen within the peripheral nerve sheath tumor schwannoma include the Antoni A and Antoni B regions. The purpose of this report is to review the significance of Antoni regions in the context of schwannomas.

Neuropathology for the neuroradiologist: rosettes and pseudorosettes.

The neuropathologic diagnosis of brain tumors entails the microscopic examination of conventional formalin-fixed paraffin-embedded tissue samples surgically removed from a radiographically defined lesion. A preliminary diagnosis is often rendered with frozen sections, though the final or definitive diagnosis usually requires more elaborate studies. Typically, the tissue is first fixed for a minimum of several hours in 10% neutral buffered formalin, processed through a series of dehydrating and clearing reagents, and embedded in a hardening wax, such as paraffin. The latter enables the tissue to be thinly sliced with a microtome, transferred to a glass slide, and then stained with dyes such as hematoxylin-eosin (H&E) that contrast the different cellular elements. Pathologists rely on visual clues such as pattern recognition when examining the stained tissue with a microscope, much as radiologists rely on gray-scale patterns of densities and intensities on images. Some histologic patterns of cellular architecture are distinctive if not pathognomonic, whereas others are less specific, but nevertheless considerably narrow the differential diagnosis. The precise biologic bases for some of the observed microscopic patterns are poorly understood, though their recognition remains useful nonetheless. Although more advanced methods of tissue examination--such as histochemical and immunohistochemical profiling, genetic analysis, and electron microscopy--have been developed, the microscopic review of H&E-stained material remains a critical component of tumor diagnosis.

Neuropathology for the neuroradiologist: Rosenthal fibers.

Distinctive intracellular structures known as inclusions may be occasionally observed on stained tissue preparations and may further suggest a specific diagnosis. Pathologists rely on these findings much as radiologists rely on findings revealed in the gray-scale patterns of densities and intensities on images. Appreciation of these inclusions can enhance the interactions of the neuroradiologist with the neuropathologist and deepen understanding of certain conditions. This report reviews the neuropathologically observed intracellular inclusions known as Rosenthal fibers in the context of Alexander disease and slow-growing tumors such as pilocytic astrocytoma.

Neuropathology for the neuroradiologist: palisades and pseudopalisades.

Histologic patterns of cellular architecture often suggest a tissue diagnosis. One distinctive histologic pattern seen within some tumors of the nervous system is the palisade. The purpose of this report is to review the significance of palisades and pseudopalisades in the context of such tumors as schwannomas and glioblastomas.

The Benefits of High Relaxivity for Brain Tumor Imaging: Results of a Multicenter Intraindividual Crossover Comparison of Gadobenate Dimeglumine with Gadoterate Meglumine (The BENEFIT Study).

BACKGROUND AND PURPOSE: Gadobenate dimeglumine (MultiHance) has higher r1 relaxivity than gadoterate meglumine (Dotarem) which may permit the use of lower doses for MR imaging applications. Our aim was to compare 0.1- and 0.05-mmol/kg body weight gadobenate with 0.1-mmol/kg body weight gadoterate for MR imaging assessment of brain tumors. MATERIALS AND METHODS: We performed crossover, intraindividual comparison of 0.1-mmol/kg gadobenate with 0.1-mmol/kg gadoterate (Arm 1) and 0.05-mmol/kg gadobenate with 0.1-mmol/kg gadoterate (Arm 2). Adult patients with suspected or known brain tumors were randomized to Arm 1 (70 patients) or Arm 2 (107 patients) and underwent 2 identical examinations at 1.5 T. The agents were injected in randomized-sequence order, and the 2 examinations were separated by 2-14 days. MR imaging scanners, imaging sequences (T1-weighted spin-echo and T1-weighted high-resolution gradient-echo), and acquisition timing were identical for the 2 examinations. Three blinded readers evaluated images for diagnostic information (degree of definition of lesion extent, lesion border delineation, visualization of lesion internal morphology, contrast enhancement) and quantitatively for percentage lesion enhancement and lesion-to-background ratio. Safety assessments were performed. RESULTS: In Arm 1, a highly significant superiority (P < .002) of 0.1-mmol/kg gadobenate was demonstrated by all readers for all end points. In Arm 2, no significant differences (P > .1) were observed for any reader and any end point, with the exception of percentage enhancement for reader 2 (P < .05) in favor of 0.05-mmol/kg gadobenate. Study agent-related adverse events were reported by 2/169 (1.2%) patients after gadobenate and by 5/175 (2.9%) patients after gadoterate. CONCLUSIONS: Significantly superior morphologic information and contrast enhancement are demonstrated on brain MR imaging with 0.1-mmol/kg gadobenate compared with 0.1-mmol/kg gadoterate. No meaningful differences were recorded between 0.05-mmol/kg gadobenate and 0.1-mmol/kg gadoterate.

The role of nonionic myelography in the diagnosis of lumbar disc herniation.

RATIONALE AND OBJECTIVES: The accuracy and safety of nonionic myelography, unenhanced computed tomography (CT), and magnetic resonance (MR) in the diagnosis of lumbar disc herniation are reviewed. The comparative costs of these tests are also considered. METHODS: The accuracy of imaging tests that diagnose disc herniations was established by conducting a Medline search between 1985 and 1992. The morbidity associated with these tests are less formally established from selected articles. Finally, the mediocre reimbursement rates of these tests are reviewed. RESULTS AND CONCLUSIONS: The evolution of nonionic contrast media from the first to the second generation has been accompanied by a notable decrease in adverse reactions. Although nonionic myelograms are now better tolerated by patients, noninvasive imaging with CT and MR imaging has become as accurate as or more accurate than lumbar myelography, and should replace it as a screening test. Computed tomography may have advantages over MR imaging when issues of availability and cost are considered. In contrast to lumbar myelography, CT myelography may continue to be a useful method for clarifying ambiguous results of noninvasive tests. The morbidity associated with CT myelography can be minimized by using low doses of a nonionic agent, keeping the patient well hydrated, and using a small lumbar puncture needle. The incidence of adverse reactions can be expected to decrease further as new nonionic dimers become clinically available.

Magnetic resonance imaging in patients with central nervous system pathology: a comparison of OptiMARK (Gd-DTPA-BMEA) and Magnevist (Gd-DTPA).

RATIONALE AND OBJECTIVES: The objective of the two pivotal phase 3 studies was to evaluate the safety and efficacy of OptiMARK (Gd-DTPA-bis(methoxyethylamide) [Gd-DTPA-BMEA]) compared with Magnevist (Gd-DTPA) in magnetic resonance imaging of the central nervous system. METHODS: Two multicenter, randomized, double-blind, parallel group studies were conducted in 395 patients with known or suspected central nervous system pathology. Subjects were randomized to receive a single 0.1 mmol/kg intravenous injection of either Gd-DTPA-BMEA or Gd-DTPA. The safety of Gd-DTPA-BMEA and Gd-DTPA was monitored for up to 72 hours after study drug administration. Precontrast and postcontrast administration magnetic resonance scans were acquired using identical imaging planes and techniques. RESULTS: No deaths or unexpected adverse events were reported in either group. A comparison of adverse events by intensity and relation demonstrated no statistically significant differences between the two groups. Gd-DTPA-BMEA and Gd-DTPA were equivalent with respect to confidence in diagnosis, conspicuity, and border delineation. CONCLUSIONS: Gd-DTPA-BMEA and Gd-DTPA demonstrated comparable efficacy profiles, and the safety profiles were considered similar.

Spiral CT of the larynx.

PURPOSE: To compare conventional and spiral CT studies of the larynx. METHODS: Ten patients had both conventional and spiral CT studies of the neck using 5-mm section collimation and 5-mm increments. The spiral scans also were reconstructed at 2-mm increments. Five patients had two spiral CT larynx studies with 5-mm and 2-mm collimation. Two observers independently rated the visibility of laryngeal structures and absence of motion artifact in the studies and assigned values from 1 (poor) to 4 (excellent). RESULTS: The spiral scan images showed less motion artifact (1.9 versus 3.6) and better anatomic detail (2.3 versus approximately 2.6). Thinner reconstruction intervals and sections gave better anatomic detail (2.3 versus approximately 3.3). Interobserver kappa was 0.65. CONCLUSION: Spiral is better than conventional CT scanning when studying the larynx.

MR of postoperative syringomyelia.

Twenty-seven MR scans of 20 patients surgically treated for syringomyelia were reviewed. Thirteen patients had syringomyelia associated with the Chiari I malformation, four cases were posttraumatic, and three were idiopathic. The operations performed included syringosubarachnoid and syringoperitoneal shunts, myelotomies, and foramen magnum decompressions. Three of the foramen magnum decompressions had associated posterior fossa duroplasties, two had fourth-ventricle-to-subarachnoid shunts, and two had plugging at the obex. On 20 scans of patients in whom the syrinx cavity had been shunted, the shunt catheter was seen in 15 (75%). When adequately treated by shunting, syringes are completely collapsed and show no flow void. Nine patients were treated by foramen magnum decompression; all were well seen by MR. Three of these patients had a poor clinical result; these were the only patients in whom CSF was not seen between the foramen magnum and the neural structures of the posterior fossa on any images. The proposed mechanisms of syrinx formation and extension are discussed and related to the surgical procedures used to treat syringomyelia.

Significance of cerebellar tonsillar position on MR.

It has been noted that a low degree of ectopia of the cerebellar tonsils on MR is of questionable significance. We measured the position of the cerebellar tonsils with respect to the inferior aspect of the foramen magnum in 200 normal patients and in 25 patients with a firm diagnosis of Chiari I malformation. In the normal group, the mean position of the tonsils was 1 mm above the foramen magnum with a range from 8 mm above the foramen magnum to 5 mm below. In the patients with Chiari I malformations, the mean position was 13 mm below the foramen magnum with a range from 3 mm below the foramen magnum to 29 mm below. Fourteen percent of normal patients had tonsils extending slightly below the foramen magnum. If 2 mm below the foramen magnum is taken as the lowest extent for tonsils in a normal patient, our sensitivity in predicting symptomatic patients is 100% and our specificity is 98.5% (three false positives). If 3 mm below the foramen magnum is taken as the lowest normal tonsillar position, our sensitivity is 96% and our specificity is 99.5%. MR demonstration of less than 2 mm of tonsillar ectopia is probably of no clinical significance in the absence of syringomyelia.

Chondrosarcoma of the larynx: CT features.

PURPOSE: To define the typical CT features of chondrosarcoma of the larynx. PATIENTS AND METHODS: Results of CT studies, performed on 10 patients with pathologically proved chondrosarcoma of the larynx, were retrospectively reviewed and correlated with clinical presentation. RESULTS: In all patients, the mass was detected on CT. The most frequent site of origin of the tumor was the cricoid cartilage (nine cases) followed by the thyroid cartilage (one case). Coarse or stippled calcification within the tumor was the most helpful radiologic finding and was seen in every case. In eight patients, the tumor had both an endolaryngeal and an extralaryngeal growth pattern, whereas in two patients the tumor was entirely endolaryngeal. Hoarseness, dyspnea, and dysphagia were the most common symptoms. In all patients presenting with dyspnea, the tumor exhibited endolaryngeal components. In patients presenting with hoarseness, three tumors had endolaryngeal and extralaryngeal components and two tumors were entirely endolaryngeal. CONCLUSION: Cross-sectional imaging afforded excellent evaluation of the airway as well as the extralaryngeal component of the tumor.

Screening CT of the brain determined by CD4 count in HIV-positive patients presenting with headache.

BACKGROUND AND PURPOSE: Few studies have examined HIV-positive patients presenting with uncomplicated headache for clinical variables that might be predictive of those patients who would most benefit from CT. Because of the value of CD4 counts in predicting the relative risk of developing opportunistic infections and neoplasms, we assessed the diagnostic yield of screening CT in HIV-positive patients presenting with headache as sorted by CD4 count. METHODS: We reviewed CT scan results and CD4 counts in patients presenting with headache uncomplicated by altered mental status, meningeal signs, neurologic findings, or symptoms of subarachnoid hemorrhage. For analysis, scans were considered positive or negative and were grouped according to CD4 counts of less than 200 cells/microL, 200 to 499 cells/microL, and equal to or greater than 500 cells/microL. The results were then analyzed using the chi2 test. RESULTS: One hundred seventy-eight HIV-positive patients underwent a total of 204 unenhanced and contrast-enhanced CT examinations. One hundred twenty-eight (62.7%) of the scans were negative, and 76 (37.3%) were positive. Of the positive scans, 58 (76.3%) showed atrophy only and 18 (23.7%) showed mass lesions or white matter lesions. All cases that were positive for mass lesions or white matter lesions occurred in patients with CD4 counts less than 200 cells/microL (P = .04). CONCLUSION: A recent CD4 count provides an important predictor variable when considering performing CT in HIV-positive patients presenting with uncomplicated headache. Performing CT of the head for patients with CD4 counts equal to or greater than 200 cells/microL is of questionable value considering the low prevalence of positive CT findings. For this select group of patients, MR imaging may be more appropriate than CT. Patients with CD4 counts less than 200 cells/microL should undergo CT because of the high prevalence of positive scans.

Tethered cord syndrome from a choristoma of müllerian origin. Case report.

The authors report a case of tethered cord syndrome due to a choristoma of müllerian origin located in the spinal cord at the lumbosacral junction. Two similar cases were found upon review of the literature. The embryology of this lesion is discussed.

Relationship between patient-based descriptions of sinusitis and paranasal sinus computed tomographic findings.

OBJECTIVE: To evaluate the relationship of paranasal sinus symptoms with coronal computed tomographic (CT) findings. DESIGN: Prospective comparison of patient-based symptoms with imaging findings. SETTING: Primary care and referral center office and hospital practices. PATIENTS: Of 586 consecutive patients referred by otolaryngologists and primary care physicians for CT of the paranasal sinuses, 221 (151 women and 70 men; age range, 13-82 years; mean age, 44 years) participated by completing the Sino-Nasal Outcome Test-20 (SNOT-20) clinical questionnaire immediately before undergoing CT. MAIN OUTCOME MEASURES: Radiologists blinded to the patients' responses scored the degree of mucosal thickening at each of 12 sites on CT scans using a staged scale of severity (0-2 points). Bivariate analysis was performed to assess the relationship between patients' symptoms and CT findings. RESULTS: The SNOT-20 scores ranged from 0 (normal) to 78 (mean, 34). The most commonly reported symptom was fatigue. The CT scores ranged from 0 (normal) to 24 (mean, 4.07). Seventy-five patients (34%) had normal findings on the CT scan. The maxillary sinus was the most commonly involved site (96 patients, or 43%). The SNOT-20 and CT scores failed to significantly correlate (r = 0.11, P < or = .09). When the subset of patients with "positive" or "very positive" CT scans were considered, no significant correlation was observed (r = 0.12, P < or = .16). For the 132 patients reporting facial pain, the mean CT score was lower than for patients without facial pain (3.78 vs 4.78, P = .21). CONCLUSION: Patient-based reports of paranasal sinus symptoms failed to correlate with findings on CT scans; therefore, CT should be reserved for delineating the anatomy and pattern of inflammatory paranasal disease prior to surgical intervention.

Closure of clival cerebrospinal fluid fistula with biocompatible osteoconductive polymer.

Cerebrospinal fluid fistula into the upper airway often results in meningitis. Closure of fistulas is usually effective using conventional surgical techniques to reconstruct the defect. We report a case of cerebrospinal fluid fistula into the sphenoid sinus and nasopharynx secondary to resection of a clivus chordoma that resisted conventional attempts at closure, including a rectus abdominus free flap. Closure of the fistula was accomplished with the use of a novel alloplast, biocompatible osteoconductive polymer. Follow-up for more than 1 year shows no evidence of rejection, infection, or recurrent cerebrospinal fluid rhinorrhea.

Comparison of computed tomography myelography and magnetic resonance imaging in the evaluation of cervical spondylotic myelopathy and radiculopathy.

STUDY DESIGN: A cross-sectional retrospective radiologic study. OBJECTIVES: To establish concordance rates between interpretations of computed tomography myelography and magnetic resonance imaging in patients with degenerative cervical spine disease. SUMMARY OF BACKGROUND DATA: Observed discrepancies in interpretation of computed tomography myelography and magnetic resonance imaging question the reliability of comparisons between these two methods. METHODS: This study blindly and randomly evaluated cervical computed tomography myelography and magnetic resonance imaging in 20 patients referred for clinically diagnosed cervical spondylotic radiculopathy, myelopathy, or both. The discovertebral joints, facet joints, lateral recesses, cord size, spinal canal, and neural foramina also were evaluated with graded scales. All results were subjected to the kappa statistic for strength of agreement. RESULTS: Agreement for interpretation of the discovertebral junction occurred in 144 of 240 sites (60%), indicating only moderately good intermethod concordance (kappa = 0.44). Intermethod agreement on the characterization of facet joint disease was only moderately good (143 of 160 sites; 89.4%; kappa = 0.52), and on characterization of lateral recess disease was poor (125 of 160 sites; 78.1%; kappa = 0.20). On degree of spinal canal compromise, there was agreement within one grade in 199 of 240 sites (82.9%; kappa = 0.42). Intermethod agreement on neural foraminal encroachment and cord size was only moderately good (kappa = 0.42 and 0.46, respectively). Computed tomography myelography tended to upgrade the spinal canal narrowing and neural foraminal encroachment. CONCLUSIONS: For most parameters of interpretation, the degree of concordance between computed tomography myelography and magnetic resonance imaging is only moderately good, with discrepancies noted especially in the differentiation of disc and bony pathology. These methods should be viewed as complementary studies.

Lesions of the cauda equina: a clinical and pathology review from the Armed Forces Institute of Pathology.

We reviewed the clinical records of 149 patients with pathologically proved cauda equina lesions in order to define the relative frequency and clinical presentations of the various diagnoses. The most common pathology was ependymomas (47 patients) followed in frequency by nerve sheath tumors (35 patients), metastases (27 patients), nonependymal glial neoplasms (six patients), meningiomas (six patients), lipomas (five patients), paragangliomas (five patients) and various other diagnoses (19 patients). Mean patient age at presentation for the various lesions included: metastases (51.5 years), nerve sheath tumors (49.7 years), nonependymal glial tumors (46.5 years), paragangliomas (41.2 years), ependymomas (38.3 years), meningiomas (34.7 years), and lipomas (18.4 years). ANOVA showed that the relationship between age and diagnosis for these groups to be statistically significant at a high level (P = 0.002). Low back pain was the most common symptom and occurred in 44 patients. Other symptoms included unilateral lower extremity pain or tenderness (24 patients), bilateral lower extremity pain or tenderness (16 patients), and bilateral lower extremity weakness (16 patients). No relationship between pathologic diagnosis and specific symptoms was found.

Cochlear implantation in children with inner ear malformations.

We performed a case study and intervention study, with follow-up of 1 to 5 years, in 4 children with inner ear malformations who underwent implantation of a multichannel cochlear implant (Nucleus, Cochlear Corporation) at ages 3 to 12 years. Malformations included a common cavity deformity, 2 incomplete partitions, and 1 case of isolated bilateral vestibular aqueduct enlargement. One child had a single-channel implant placed at 3 years of age, and this was exchanged for a 22-channel implant at age 9. One child had her implant placed at age 4.5 years, but due to complications from a cerebrospinal fluid (CSF) leak had the initial implant removed and replaced at age 5 years during repair of the CSF leak. Intraoperative findings included a CSF leak at the time of surgery in 3 patients. One patient contracted bacterial meningitis 7 months postimplantation that was thought to be secondary to acute otitis media in the unoperated ear. Bilateral CSF leaks were noted in the middle ear by a lumbar puncture radionuclide and fluorescein dye study. Successful repair of the CSF leaks and reimplantation of the cochlear implant was carried out in this patient. Mapping and programming of the implant was found to be challenging in each of these patients. All patients demonstrated improved performance after implantation. Two patients demonstrated some open-set speech perception. One patient demonstrates improved use of temporal cues in a structured closed set. One patient has achieved no significant speech recognition at this time, but does have improved sound detection and awareness. Cochlear implantation in children with congenital inner ear abnormalities can be a successful method of rehabilitation. It should be recognized that the postoperative speech perception results may be highly variable among patients, and that intraoperative complications may occur.

Magnetic resonance imaging in internal carotid artery agenesis with computed tomography and angiographic correlation--case reports.

The authors present two cases of agenesis of the internal carotid artery (ICA) discovered incidentally on magnetic resonance imaging and confirmed on computed tomography, magnetic resonance angiography, and conventional angiography. They also propose a clinical algorithm for the workup of patients with suspected absence of the ICA.