Recording event-related activity under hostile magnetic resonance environment: Is multimodal EEG/ERP-MRI recording possible?

Event-related potentials (ERPs) have high temporal resolution, but insufficient spatial resolution; the converse is true for the functional imaging techniques. The purpose of the study was to test the utility of a multimodal EEG/ERP-MRI technique which combines electroencephalography (EEG) and magnetic resonance imaging (MRI) for a simultaneously high temporal and spatial resolution. The sample consisted of 32 healthy young adults of both sexes. Auditory stimuli were delivered according to the active and passive oddball paradigms in the MRI environment (MRI-e) and in the standard conditions of the electrophysiology laboratory environment (Lab-e). Tasks were presented in a fixed order. Participants were exposed to the recording environments in a counterbalanced order. EEG data were preprocessed for MRI-related artifacts. Source localization was made using a current density reconstruction technique. The ERP waveforms for the MRI-e were morphologically similar to those for the Lab-e. The effect of the recording environment, experimental paradigm and electrode location were analyzed using a 2x2x3 analysis of variance for repeated measures. The ERP components in the two environments showed parametric variations and characteristic topographical distributions. The calculated sources were in line with the related literature. The findings indicated effortful cognitive processing in MRI-e. The study provided preliminary data on the feasibility of the multimodal EEG/ERP-MRI technique. It also indicated lines of research that are to be pursued for a decisive testing of this technique and its implementation to clinical practice.

Is there a role for apparent diffusion coefficients in the differential diagnosis of brain tumors?

We determined the potential benefits of apparent diffusion coefficient (ADC) values of enhancing-nonenhancing solid portions, cystic-necrotic areas and surrounding edema in the differential diagnosis of brain tumors. Eighty-eight patients with brain tumors: 16 low-grade gliomas, 21 high-grade gliomas, 26 metastases and 25 meningiomas were imaged prospectively in a 1.5 Tesla magnetic resonance (MR) unit. Routine MR imaging and echo-planar diffusion-weighted imaging (DWI) with b values of 0 and 1000 mm(2)/s were performed. ADC values were obtained in different tumor parts and peritumoral edema. The ADCs of contrast-enhancing tumor regions were higher in high-grade gliomas than meningiomas (p<0.05). No significant differences were found in ADCs of contrast-enhancing regions comparing other tumor groups (p≥0.05). The ADCs in non-enhancing tumor regions did not differ between low-grade and high-grade gliomas (p≥0.05). The ADCs in cystic-necrotic regions of tumors and surrounding edema were not significantly different comparing all tumor groups (p≥0.05). There were no significant differences between ADCs of contrast-enhancing and non-enhancing regions of high-grade and low-grade gliomas (p≥0.05). No significant differences were found in ADCs of contrast-enhancing and non-enhancing areas of tumors comparing to surrounding edema (p≥0.05). ADC was not found to be useful in distinguishing different tumor types and its value in the diagnosis of brain tumors is limited due to considerable overlaps.

Imaging meningiomas: is there a need for post-contrast FLAIR?

AIM: The aim of this study was to compare post-contrast fluid-attenuated inversion recovery (FLAIR) imaging with post-contrast T1-weighted images (T1WI) in depicting meningiomas. MATERIALS AND METHODS: Twenty-nine patients with 46 meningiomas were included in this study. FLAIR and T1WI were obtained before and after intravenous administration of gadopentetate dimeglumine. The contrast enhancement degree, contrast enhancement pattern, lesion conspicuity, and the detection of the dural sign were compared between post-contrast FLAIR images and post-contrast T1WI. RESULTS: The enhencement degree on FLAIR was equal or less than T1WI for all meningiomas. Among 46 meningiomas 38 (83%) enhanced homogeneously and eight (17%) inhomogeneously on T1WI. On contrast-enhanced FLAIR images, of the total 46 meningiomas 22 (48%) enhanced homogeneously, eight (17%) inhomogeneously, whereas 14 (30%) meningiomas showed a peripheral rim enhancement not observed on T1WI. Two (5%) meningiomas showed no contrast enhancement on post-contrast FLAIR images. Among the 14 meningiomas showing rim enhancement using FLAIR imaging, 12 (85%) were measured to be 2 cm or more in diameter. A dural tail sign was found in 16 (35%) and 23 (50%) meningiomas on post-contrast T1WI and FLAIR images, respectively. CONCLUSION: In contrast to other extra-axial diseases, post-contrast FLAIR sequence was not found to be a valuable adjunct to contrast-enhanced T1WI in the depiction of meningiomas.

Candida vertebra osteomyelitis in a girl with factor X deficiency.

Candidal vertebra osteomyelitis is a rare condition which occurs primarily in immunocompromised patients. We report a 14-year-old girl with factor X deficiency who developed candida vertebra osteomyelitis during home therapy. The microorganism was probably from a contaminated peripheral cannula used for infusion of factor concentrate. This is the first such case in bleeding disorders to our knowledge.

The role of qualitative and quantitative MRI assessment of multiple sclerosis lesions according to their in evaluating the efficacy of intravenous immunoglobulin G.

We evaluation of the role of determining the distribution of brain-stem, cerebellar and cerebral lesions in number and volume by MRI in determining the efficiency of treatment of multiple sclerosis (MS). We studied 24 patients diagnosed as having relapsing and remitting MS, of whom 12 received intravenous immunoglobulin G; a control group of 12 were given placebo. In a double-blind study, MRI was obtained initially and at 3, 6 and 9 months, and interpreted without knowledge of clinical findings, laboratory tests or treatment. The lesions were classified according to their distribution and evaluated qualitatively and quantitatively. Each patient was also examined clinically and scored according to the expanded disability status scale (EDSS) following every MRI examination. All patients in the treatment group showed significant improvement. The lesions decreased in both in size and number in all sites. In the control group lesions increased both in number and size in all sites, but only the increase between 3()and 6 months was statistically significant. In both groups, significant apparent changes were detected in the cerebellum and brain stem. Volumetric evaluation was found to be more helpful than qualitative assessment.

Spontaneous bilateral internal carotid artery dissection with hypoglossal nerve palsy.

Spontaneous dissection of the extracranial internal carotid artery (ICA) is increasingly being recognized as a common vascular disease. We report on a 52-year-old-male presented with bilateral extracranial internal artery dissection and twelfth nerve palsy and review the previous literature.

Haematoma-like primary intracranial malignant fibrous histiocytoma in a 5-year-old girl.

We present CT and MRI of an intracranial malignant fibrous histiocytoma in a 5-year-old girl with headache and vomiting. This case is unusual particular by virtue of its radiological appearances and the young age of the patient.

Vertebral osteoblastoma: are radiologic structural changes necessary for diagnosis?

BACKGROUND: A case of osteoblastoma localized at the pedicle of the 10th thoracic vertebra is presented. CASE DESCRIPTION: The patient complained of nocturnal back pain not relieved by salycilates, a typical symptom of osteoblastoma. Bone scintigraphy showed a lower thoracic focus of increased osteoblastic activity; however, X-rays, computed tomography, and magnetic resonance images (MRI) were within normal limits, showing only obscure changes that were also noted in the rest of the spine. Repeat MRI with contrast revealed a focal enhancement. After pediculectomy, histopathologic examination confirmed the diagnosis of osteoblastoma. Fifteen months postoperatively, the patient is symptom-free. CONCLUSION: Our case demonstrates that some cases of osteoblastoma may not have the classical radiological appearance. Although non-contrast computed tomography and T1-weighted MRI are mildly positive in some instances, osteoblastoma is best visualized on MRI with gadolinium. Like any other neoplasm, osteoblastoma should be detected and removed early, before it can cause structural bony changes.

p53 and p16INK4A mutations during the progression of glomus tumor.

Glomus tumors are significantly rare tumors of carotid body. The great majority of these tumors are benign in character. Here we present two brothers with hereditary glomus jugulare tumor who had consanguineous parents. Radiotherapy was applied approximately 8 and 10 years ago for treatment in both cases. Eight years later, one of these cases came to our notice due to relapse. The mutation pattern of p53, p57KIP2, p16INK4A and p15NK4B genes which have roles in the cell cycle, was analyzed in tumor samples obtained from the two affected cases in the initial phase and from one of these cases at relapse. The DNA sample obtained from the case in initial diagnosis phase revealed no p53, p57KIP2, p16INK4A or p15INK4B mutation. He is still in remission phase. Despite the lack of p53, p57KIP2, p16INK4A and p15INK4B mutation at initial diagnosis the tumor DNA of the other case in relapse revealed p53 codon 243 (ATG-->ATC; met-->ile) and p16 codon 97 (GAC-->AAC; asp-->asn) missense point mutations. No loss of heterozygosity in p53 and p16INK4A was observed by microsatellite analysis of tumoral tissues in these cases. P53 and p16INK4A mutations observed in relapse phase were in conserved regions of both genes. No previous reports have been published with these mutations in glomus tumor during progression. The mutation observed in this case may due to radiotherapy. In spite of this possibility, the missense point mutations in conserved region of p53 and p16INK4A genes may indicate the role of p53 and p16INK4A in tumor progression of glomus tumors.

Unusual migration of a foreign body from the gut to a vertebral body.

We report a unique case in which a needle was accidentally swallowed and migrated into the vertebral body. Plain films and CT of the spine revealed fragmented, linear, metallic-density material in the L3 vertebral body. The possible mechanisms of the migration are discussed.

MR imaging and MR angiography in popliteal artery entrapment syndrome.

Popliteal artery entrapment (PAE) syndrome is an uncommon congenital anomaly seen in young adults causing ischemic symptoms in the lower extremities. It is the result of various types of anomalous relationships between the popliteal artery and the neighboring muscular structures. The purpose of this study was to define the role of MR imaging combined with MR angiography in the diagnosis of PAE cases. Four cases with segmental occlusion and medial displacement of popliteal artery in digital subtraction angiography (DSA) examinations were diagnosed as PAE syndrome by MR imaging and MR angiography. The DSA and MRA images are compared. All of the cases showed various degrees of abnormal intercondylar insertion of the medial head of the gastrocnemius muscle. The MR images showed detailed anatomy of the region revealing the cause of the arterial entrapment. Subclassification of the cases were done and fat tissue filling the normal localization of the muscle was evaluated. The DSA and MRA images demonstrated the length and localization of the occluded segment and collateral vascular developments equally. It is concluded that angiographic evaluation alone in PAE syndrome might result in overlooking the underlying cause of the arterial occlusion, which in turn leads to unsuccessful therapy procedures such as balloon angioplasty. Magnetic resonance imaging combined with MR angiography demonstrates both the vascular anatomy and the variations in the muscular structures in the popliteal fossa successfully, and this combination seems to be the most effective way of evaluating young adults with ischemic symptoms suggesting PAE syndrome.

MRI in neuro-Behçet's disease.

Our purpose was to characterise specific MRI findings and to determine their value in neuro-Behçet's disease. We examined 17 patients (14 men, 3 women) with neuro-Behçet's disease using T1- and T2-weighted spin-echo images and contrast-enhanced images at 0.5 T. There were 13 patients (76.5%) who had single or multiple lesions. Most of these were in the basal ganglia, brain stem or deep white matter region, giving high signal on T2-weighted images and isointense or low signal on T1-weighted images. In 3 cases (17.6%) there was linear high signal along the posterior limb of the internal capsule on T2-weighted images. This was considered as a potential differentiating feature of neuro-Behçet's disease. Contrast-enhancement was seen in 17 lesions in 7 patients.

MRI of brucella polyneuritis in a child.

MRI of a rare case of polyneuritis following brucellosis is presented. An 8-year-old boy with a history of brucellosis showed marked enlargement of the origin of the left fifth cranial nerve and contrast enhancement of the fifth cranial nerves and the Gasserian ganglion in Meckel's caves. A well-defined low-signal cystic mass showing peripheral contrast enhancement lay anteromedial to the left seventh and eighth cranial nerves. The seventh and eighth nerves showed marked enhancement. The prechiasmatic portion of the right optic nerve showed fusiform enlargement with marked contrast enhancement of the nerve and right optic tract. MRI immediately after treatment showed no enhancement of the cranial nerves. Enlargement of the origin of the left fifth cranial nerve persisted, but there was no enlargement of the optic nerve. The mass near the left seventh and eighth cranial nerves was still present with no obvious morphological change, but no longer showed peripheral enhancement.

Sapho syndrome associated with acne fulminans and prominent acromioclavicular joint involvement.

The clinical and radiological findings of a 33 year-old male patient with acne fulminans and associated SAPHO syndrome are described. The patient presented with prominent acromioclavicular joint involvement, unilateral sacroiliitis and subclavian vein compression which are relatively uncommon features of this syndrome.

The effect of contrast dose, imaging time, and lesion size in the MR detection of intracerebral metastasis.

PURPOSE: To evaluate the effect of MR contrast dose versus delayed imaging time on the detection of metastatic brain lesions based on lesion size. METHODS: Contrast MR examinations with gadoteridol were obtained in 45 patients with brain metastases. The patients were divided into two groups: 16 received cumulative standard dose (0.1 mmol/kg) and 29 received cumulative triple dose (0.3 mmol/kg). Both groups were evaluated at two dose levels (lower dose and higher dose) with two separate injections. Each patient received an initial bolus injection of either 0.05 (cumulative standard dose) or 0.1 (cumulative triple dose) mmol/kg of gadoteridol to reach the lower-dose level and underwent imaging immediately and 10 and 20 minutes later. Thirty minutes after injection, an additional bolus injection of 0.05 (cumulative standard dose) or 0.2 (cumulative triple dose) mmol/kg was administered to reach the cumulative higher-dose level (cumulative standard dose, 0.1 mmol/kg; cumulative triple dose, 0.3 mmol). Images were acquired immediately. RESULTS: There was no difference in the detection rate for lesions larger than 10 mm among T2-weighted, lower-dose immediate and delayed, or immediate higher-dose images in both study groups. Lesions smaller than 10 mm had improved detection with delayed imaging in both study groups; however, the immediate higher-dose studies still had the highest detection rate. CONCLUSION: In the evaluation of small central nervous system metastases, either delayed imaging after the injection of standard contrast dose or higher contrast dose may improve their detection, and therefore affect clinical management. Higher contrast dose (cumulative triple dose) studies appear to be more effective than delayed imaging with standard dose.

MR evaluation of acoustic schwannoma with fractional contrast doses.

OBJECTIVE: To investigate the utility of lower contrast medium doses for the detection and conspicuity of acoustic schwannomas. MATERIALS AND METHODS: The L/B (L, lesion; B, background) ratios or lesion contrast of 17 pathologically proven acoustic schwannomas studied with a standard dose (0.1 mmol/kg) of gadopentetate dimeglumine was measured. In addition, 22 patients with acoustic schwannomas were studied prospectively with fractional doses using the incremental dose technique. Each patient received an initial bolus injection of one-eight the standard dose (0.0125 mmol/kg) followed by an injection of one-eighth, one-fourth, and one-half the standard dose at 5 min intervals to achieve a cumulative dose of one-fourth, one-half and full dose, respectively. Imaging was performed immediately after each injection. RESULTS: Standard dose--The L/B ratios of pathologically proven acoustic schwannomas to mastoid air cells ranged from 14.8 to 41.2 (mean +/- SEM, 28.0 +/- 1.95), which were approximately 17 times more than those of intraparenchymal lesions. Fractional cumulative dose--Qualitative visual analysis demonstrated that all acoustic schwannomas showed apparent enhancement at one-fourth dose. Intense enhancement was noted at one-half and full dose. Quantitative analysis demonstrated the mean L/B ratios between the acoustic schwannomas and mastoid air cells of the precontrast and one-eighth, one-fourth, one-half, and full dose studies were 8.33 +/- 0.52, 11.21 +/- 0.75, 13.02 +/- 0.83, 15.38 +/- 0.98, and 18.03 +/- 1.36, respectively. CONCLUSION: The L/B ratios or lesion contrast of acoustic schwannomas at various fractional contrast medium doses was significantly higher compared with that of intraparenchymal lesions. Thus, the standard contrast medium dose may not be necessary for detection of acoustic schwannomas, and a fractional dose may be sufficient. Although the optimal fractional dose remains to be determined, one-half of the standard dose (0.05 mmol/kg) appears to be sufficient because of intense enhancement at this dose.

Delineation of gliomas with various doses of MR contrast material.

PURPOSE: To examine the effects of different gadolinium doses on the delineation of gliomas, particularly the demonstration of abnormal enhancement on T1-weighted images extending beyond the zone of apparent signal abnormality on corresponding T2-weighted images. METHODS: During phase II clinical trials of gadoteridol, 23 patients with pathologically proved gliomas were studied by MR with various doses of gadoteridol, ranging from 0.05 to 0.3 mmol/kg. RESULTS: All of the gliomas were readily detected by T2-weighted images. Twelve of 23 patients demonstrated enhancement on T1-weighted images extending beyond the zone of apparent signal abnormality demonstrated on T2-weighted images. These findings were seen in none of the six patients (0%) studied at 0.05 mmol/kg, one of five patients (20%) studied at 0.1 mmol/kg, four of five patients (80%) studied at 0.2 mmol/kg, and seven of seven patients (100%) studied at 0.3 mmol/kg. CONCLUSIONS: The detection of symptomatic gliomas does not require a contrast agent because they are generally large and readily demonstrated on T2-weighted images. However, the area of postcontrast enhancement of gliomas seems to be greater with higher doses of contrast agent. The cause of the abnormal enhancement extending beyond the zone of apparent signal abnormality on T2-weighted images seen in this limited study is unknown and probably represents tumor infiltration. The frequency of detection of such findings appears to be proportional to the dose of contrast material used.

MR of fetal central nervous system abnormalities.

PURPOSE: To investigate whether MR can provide additional information on fetuses with central nervous system abnormalities as demonstrated by ultrasonography. METHODS: Fetal MR examinations were studied prospectively in 22 pregnant women whose fetuses showed evidence of anomalies on ultrasound performed in the High-Risk Obstetric Clinic. RESULTS: In 19 of 22 cases, postpartum confirmatory diagnoses were obtained by MR or CT examinations, autopsy, or surgery. In general, the image quality of MR is comparable with that of ultrasound. However, in six of 22 cases (27%), MR provided additional information that altered the ultrasound diagnosis; these included cases of infarction, diastematomyelia, normal hemimegalencephaly with early myelination, Dandy-Walker variant, and lipoma. All of these cases had postpartum confirmation. The additional information changed the treatment in three of six patients (no intervention or elective abortion). CONCLUSIONS: In certain situations MR can add valuable information to that obtained by sonography in the evaluation of the fetal central nervous system.

Venous sinus occlusive disease: MR findings.

PURPOSE: To study MR patterns of venous sinus occlusive disease and to relate them to the underlying pathophysiology by comparing the appearance and pathophysiologic features of venous sinus occlusive disease with those of arterial ischemic disease. METHODS: The clinical data and MR examinations of 26 patients with venous sinus occlusive disease were retrospectively reviewed with special attention to mass effect, hemorrhage, and T2-weighted image abnormalities as well as to abnormal parenchymal, venous, or arterial enhancement after intravenous gadopentetate dimeglumine administration. Follow-up studies when available were evaluated for atrophy, infarction, chronic mass effect, and hemorrhage. RESULTS: Mass effect was present in 25 of 26 patients. Eleven of the 26 had mass effect without abnormal signal on T2-weighted images. Fifteen patients had abnormal signal on T2-weighted images, but this was much less extensive than the degree of brain swelling in all cases. No patient showed abnormal parenchymal or arterial enhancement. Abnormal venous enhancement was seen in 10 of 13 patients who had contrast-enhanced studies. Intraparenchymal hemorrhage was seen in nine patients with high signal on T2-weighted images predominantly peripheral to the hematoma in eight. Three overall MR patterns were observed in acute sinus thrombosis: 1) mass effect without associated abnormal signal on T2-weighted images, 2) mass effect with associated abnormal signal on T2-weighted images and/or ventricular dilatation that may be reversible, and 3) intraparenchymal hematoma with surrounding edema. CONCLUSION: MR findings of venous sinus occlusive disease are different from those of arterial ischemia and may reflect different underlying pathophysiology. In venous sinus occlusive disease, the breakdown of the blood-brain barrier (vasogenic edema and abnormal parenchymal enhancement) does not always occur, and brain swelling can persist up to 2 years with or without abnormal signal on T2-weighted images. Abnormal signal on T2-weighted images may be reversible and does not always indicate infarction.

Brain parenchymal infection in bone marrow transplantation patients: CT and MR findings.

OBJECTIVE: The purpose of this study was to assess the MR and CT appearance of brain infection after bone marrow transplantation and to correlate the appearances with laboratory and pathologic findings. MATERIALS AND METHODS: We retrospectively reviewed the records of seven bone marrow transplant recipients with radiologic evidence of brain infection. RESULTS: Forty-one lesions were detected in seven patients with proved infectious foci outside the brain before brain infection was suspected clinically. Six patients had low total WBC or lymphocyte counts and one patient had normal total WBC and lymphocyte counts. Most lesions in patients with low total WBC or lymphocyte counts showed no appreciable edema or contrast enhancement. However, all lesions detected in the patient with normal total WBC and lymphocyte counts showed marked vasogenic edema and ring enhancement. CONCLUSION: Brain infection in bone marrow transplant recipients during immunosuppression exhibited MR characteristics different from those typically seen in immunocompetent patients. This appearance may be related to a diminished immunologic/inflammatory response.