Acute CT perfusion changes in seizure patients presenting to the emergency department with stroke-like symptoms: correlation with clinical and electroencephalography findings.

AIM: To determine acute computed tomography perfusion (CTP) changes in seizure patients presenting with stroke-like symptoms and to correlate those changes with clinical presentation and electroencephalography (EEG). MATERIALS AND METHODS: The medical records of all patients who presented to the emergency department with acute stroke-like symptoms and underwent CTP (n=1085) over a 5.5-year period were reviewed. Patients were included who had primary seizure as the final diagnosis, and underwent CTP within 3 hours of symptom onset. A subset of patients had a follow-up EEG within 7 days. The perfusion changes and EEG findings were compared between different clinical presentations. RESULTS: Eighteen of 1085 patients (1.7%) who underwent CTP following an acute stroke-like presentation were included. The abnormality on CTP was usually focal, unilateral hyperperfusion - increased relative cerebral blood flow (rCBF) and volume (rCBV) (n=14/18), which most often affected the temporal lobe. Those patients who presented with a motor or speech deficit (n=12) had a higher temporal lobe rCBV, and rCBF, and lower relative mean transit time (rMTT) compared to those with non-focal neurological deficit at presentation. Early EEG was available in 13 patients; a sharp-spike epileptiform EEG discharge pattern (n=5) was associated with higher temporal lobe ipsilateral rCBF and rCBV, and lower rMTT on admission CTP examination. CONCLUSION: Seizure patients who present with a unilateral motor or speech deficit most commonly have contralateral hyperperfusion in the corresponding eloquent brain regions on the acute-stage CTP examination. In such patients, epileptiform discharges on the early follow-up EEG are associated with ipsilateral hyperperfusion on the admission CTP.

Comparison of spin-echo and gradient-echo T1-weighted and spin-echo T2-weighted images at 3T in evaluating term-neonatal myelination.

SUMMARY: A prior clinical report of 3T MR imaging in subsequently healthy very premature neonates imaged at term-equivalent age found that both gradient recalled-echo-T1WI and spin-echo-T2WI showed higher rates of myelinated structures, compared with spin-echo-T1WI. The current study set out to assess those rates on the same sequences at 3T in term neonates and thus consisted of 16 term neonates with normal-appearing MR imaging findings who subsequently had normal findings at clinical follow-up. Two neuroradiologists independently assessed 19 structures in those infants on all 3 sequences. Gradient recalled-echo-T1WI showed a slightly higher rate of myelination (57.2%-72.4% of all structures) and interobserver agreement (κ = 0.546, P < .0001) than spin-echo-T2WI (58.2%-64.8%; κ = 0.468, P < .0001), while spin-echo-T1WI had the lowest myelination rate and agreement (25.0%-48.4%; κ = 0.384, P < .0001). Both observers noted that the following structures were myelinated in 88%-100% of patients on gradient recalled-echo-T1WI: the brachium of the inferior colliculus, decussation of the superior cerebellar peduncle, habenular commissure, medial lemniscus, pyramidal decussation, posterior limb of the internal capsule, and superior cerebellar peduncle; on spin-echo-T2WI, there was myelination in 88%-100% of the following structures: the brachium of the inferior colliculus, decussation of the superior cerebellar peduncle, inferior cerebellar peduncle, medial lemniscus, and posterior limb of the internal capsule. In conclusion, this study confirmed that similar to the findings in term-equivalent-age premature infants, myelination changes in term neonates may be best assessed on both gradient recalled-echo-T1WI and spin-echo-T2WI at 3T, and not on spin-echo-T1WI.

Comparison of spin-echo T1- and T2-weighted and gradient-echo T1-weighted images at 3T in evaluating very preterm neonates at term-equivalent age.

Term-equivalent imaging can assess myelination status in very preterm infants (<30 weeks' gestational age at birth). However, myelination assessment has yet to be compared among GRE-T1WI, SE-T1WI, and SE-T2WI at 3T. We aimed to compare the rates of myelination among those 3 sequences in 11 very preterm neonates who underwent 3T MR imaging at term-equivalent age and subsequently had normal neurologic development. On each sequence, 2 neuroradiologists individually assessed 22 structures. SE-T2WI depicted a higher myelination rate (present in 58.2%-66.4% of all structures) than either GRE-T1WI (51.6%-63.9%) or SE-T1WI (20.5%-38.5%), while GRE-T1WI had the highest interobserver agreement (κ, 0.56; P < .0001). Myelination was present in 90%-100% of patients within the corpus callosum splenium, DSCP, ICP, lateral lemniscus, and spinal tract/nucleus of cranial nerve V on SE-T2WI, and in the DSCP, ICP, lateral lemniscus, medial lemniscus, pyramidal decussation, PLIC, and superior cerebellar peduncle on GRE-T1WI, occurring in similar structures as previously shown at 1.5T and 1T. However, it is not clear whether these findings represent true myelination versus precursors to myelination.

Detection of microhemorrhage in posterior reversible encephalopathy syndrome using susceptibility-weighted imaging.

BACKGROUND AND PURPOSE: PRES-related vasogenic edema is potentially reversible while hemorrhage occurs in only 15.2%-17.3% of patients. However, the true incidence of hemorrhage could be higher when SWI is considered. Thus, we set out to determine the incidence of MH, SAH, and IPH in PRES by using SWI and to particularly evaluate whether such MHs are reversible. MATERIALS AND METHODS: Thirty-one patients with PRES and SWI were included, 17 having follow-up SWI. Two neuroradiologists reviewed SWI, FLAIR, DWI, and CE-T1WI. The presence and number of MHs (<5 mm) on SWI, SAH, and IPH (>5 mm) were recorded at presentation and follow-up. We evaluated associations between the presence of MH on SWI and DWI lesions, SAH, IPH, contrast enhancement, and MR imaging severity. RESULTS: Hemorrhage was present in 20/31 patients (64.5%), with MHs on SWI in 18/31 (58.1%) at presentation and in 11/17 (64.7%) at follow-up. SAH was present in 3/31 on SWI and 4/31 on FLAIR, while 2/31 had IPH. At follow-up, no patients had acquired new MHs; 2/5 MHs in 1 patient resolved. Four patients with available SWI before PRES developed MHs after PRES onset. No association was found between the presence of MHs on SWI and DWI, SAH, IPH, enhancement, and MR imaging severity (all P > .05). CONCLUSIONS: SWI showed a higher rate of MH than previously described, underscoring the potential of SWI in evaluating PRES. Such MHs typically persist and may develop after PRES onset. However, the clinical relevance of MHs in PRES is yet to be determined. We propose that MHs in PRES relate to endothelial cell dysfunction.

Distinguishing 3 classes of corpus callosal abnormalities in consanguineous families.

OBJECTIVE: We sought to create a classification system for pediatric corpus callosal abnormalities (CCA) based upon midline sagittal brain MRI. We used the term CCA for patients with structural variants of the corpus callosum, excluding patients with interhemispheric cyst variant or pure dysplasia without hypoplasia. Currently, no system exists for nonsyndromic forms of CCA, and attempts to create such a system have been hampered by highly variable morphology in patients with sporadic CCA. We reasoned that any useful strategy should classify affected family members within the same type, and that phenotypic variability should be minimized in patients with recessive disease. METHODS: We focused recruitment toward multiplex consanguineous families, ascertained 30 patients from 19 consanguineous families, and analyzed clinical features together with brain imaging. RESULTS: We identified 3 major CCA classes, including hypoplasia, hypoplasia with dysplasia, and complete agenesis. Affected individuals within a given multiplex family usually displayed the same variant of the class of abnormality and they always displayed the same class of abnormality within each family, or they displayed complete agenesis. The system was validated among a second cohort of 10 sporadic patients with CCA. CONCLUSIONS: The data suggest that complete agenesis may be a common end-phenotype, and implicate multiple overlapping pathways in the etiology of CCA.

Syndrome of megalencephaly, polydactyly, and polymicrogyria lacking frank hydrocephalus, with associated MR imaging findings.

Megalencephaly, polymicrogyria, polydactyly, and hydrocephalus (MPPH) syndrome has been recently recognized and is very rare. Each case reported so far has demonstrated hydrocephalus to varying degrees. We report an infant with MPPH syndrome, but lacking frank hydrocephalus. The additional finding of an abnormally elongated pituitary infundibulum has not been described in this syndrome and, along with the presence of a regressing cystic cavum septum pellucidum, suggests that chronic underlying hydrocephalus may have been present.

Dilation of the subarachnoid spaces surrounding the cranial nerves with petrous apex cephaloceles in Usher syndrome.

Limited studies of brain MR imaging findings in Usher syndrome have reported atrophy with enlarged subarachnoid spaces. However, the specific appearance of the subarachnoid spaces surrounding the cranial nerves has not yet been described. Herein we describe the skull base MR imaging findings in an adult with Usher syndrome. Multiple cranial nerve exits were enlarged to the point of causing cephaloceles with bony remodeling. A combination of uncommon findings in this rare disorder raises the question of an etiologic association.

Detection of aneurysms by 64-section multidetector CT angiography in patients acutely suspected of having an intracranial aneurysm and comparison with digital subtraction and 3D rotational angiography.

BACKGROUND AND PURPOSE: Four-section multisection CT angiography (MSCTA) accurately detects aneurysms at or more than 4 mm but is less accurate for those less than 4 mm. Our purpose was to determine the accuracy of 64-section MSCTA (64MSCTA) in aneurysm detection versus combined digital subtraction angiography (DSA) and 3D rotational angiography (3DRA). MATERIALS AND METHODS: In a retrospective review of patients studied because of acute symptoms suspicious for arising from an intracranial aneurysm, 63 subjects were included who had undergone CT angiography (CTA). Of these, 36 underwent catheter DSA; all but 4 were also studied with 3DRA. The most common indication was subarachnoid hemorrhage (SAH; n = 43). Two neuroradiologists independently reviewed each CTA, DSA, and 3DRA. RESULTS: A total of 41 aneurysms were found in 28 patients. The mean size was 6.09 mm on DSA/3DRA and 5.98 mm on 64MSCTA. kappa was excellent (0.97) between the aneurysm size on 64MSCTA and DSA/3DRA. Ultimately, 37 aneurysms were detected by DSA/3DRA in 25 of the 36 patients who underwent conventional angiography. The reviewers noted four 1- to 1.5-mm sessile outpouchings only on 3DRA; none were considered a source of SAH. One 64MSCTA was false positive, whereas one 2-mm aneurysm was missed by CTA. The sensitivity of CTA for aneurysms less than 4 mm was 92.3%, whereas it was 100% for those 4-10 mm and more than 10 mm, excluding the indeterminate, sessile lesions. CONCLUSIONS: In comparison with the available literature, 64MSCTA may have improved the detection of less than 4-mm aneurysms compared with 4- or 16-section CTA. However, the combination of DSA with 3DRA is currently the most sensitive technique to detect untreated aneurysms and should be considered in suspicious cases of SAH where the aneurysm is not depicted by 64MSCTA, because 64MSCTA may occasionally miss aneurysms less than 3-4 mm size.

Reversible findings of restricted diffusion in 5-fluorouracil neurotoxicity.

A 35-year-old woman presented with neurotoxicity correlated to an i.v. regimen of 5-fluorouracil as episodes of acute confusional state and abnormalities of symmetrically restricted diffusion in the periventricular white matter and corpus callosum. On discontinuing the medication, the areas of severely restricted diffusion had entirely resolved, with minimal residual T2 signal abnormality. In this case, immediate discontinuation of the chemotherapeutic agent apparently reversed the patient's symptoms and findings on MRI. The scant information available in the published literature regarding this phenomenon is reviewed with regard to 5-fluorouracil.

Multi-slice computed tomography angiography in the detection of residual or recurrent cerebral aneurysms after surgical clipping.

PURPOSE: To assess the diagnostic accuracy of multi-slice computed tomography (MSCT) angiography compared to digital subtraction angiography (DSA) in detecting residual or recurrent aneurysms in patients undergoing aneurysm clipping surgery. MATERIAL AND METHODS: Eight patients with nine aneurysms who had both MSCTA and DSA were included in the study. Two independent experienced neuroradiologists evaluated the examinations. RESULTS: Accuracy, sensitivity, and specificity of detecting residual or recurrent aneurysms on MSCTA were 0.80, 0.60, and 1.00, respectively. Positive and negative predictive values were 1.00 and 0.71, respectively. CONCLUSION: MSCTA is a promising technique for evaluating residual or recurrent aneurysms in patients undergoing surgical treatment of aneurysm with titanium clips.

Intracranial metastasis via transplacental (vertical) transmission of maternal small cell lung cancer to fetus: CT and MRI findings.

We present the computed tomography (CT) and magnetic resonance imaging (MRI) findings of brain metastases in an unusual case of a premature, 33-week gestational age neonate who was emergently delivered from a mother suspected of having lung cancer according to imaging performed during the third trimester of pregnancy. Owing to the presence of placental metastases noted after delivery, the fetus had initial screening with brain MRI and chest/abdomen CT as well as serial screening imaging studies during the first 5 months of life, all of which were apparently normal. However, serial examinations eventually revealed a cerebellar lesion that significantly improved after chemotherapy but recurred and enlarged within a few months. This lesion was later confirmed to be metastasis by subsequent biopsy and resection. More metastatic lesions were identified in the frontal and temporal lobes on follow-up MRI. In the setting of aggressive maternal malignancy (without known fetal primary malignancy) an intracranial mass can, on the exceedingly rare occasion, result from maternal high-grade malignancy and the neuroradiologist should be alerted to this phenomenon.

A retained neurointerventional microcatheter fragment in the anterior communicating artery aneurysm in multi-slice computed tomography angiography.

We present a case of multi-slice computed tomography angiography of a 60-year-old patient with a retained fragment of microcatheter within an anterior communicating artery (AcomA) aneurysm. This is a rare complication of Guglielmi detachable coil embolization. After an unsuccessful embolization procedure, the patient underwent surgery. During clipping of an AcomA aneurysm, the microcatheter traveled up the pericallosal branch of the right anterior cerebral artery. Subsequently, the microcatheter fragment did not prevent normal blood flow through the artery, and the patient has been doing well without neurological sequelae.

CT perfusion imaging in the management of posterior reversible encephalopathy.

A 13-year-old girl with a renal transplant presented with hypertension and seizures. CT and MRI demonstrated typical bilateral parietal, occipital and posterior frontal cortical and subcortical edema, thought to represent posterior reversible encephalopathy syndrome. The cause was presumed to be hypertension. Antihypertensive therapy was started, lowering of the blood pressure in the range of 110-120 mmHg systolic. However, stable xenon (Xe) CT perfusion imaging revealed ischemia within the left parietal occipital region. The antihypertensive was adjusted which increased both the systolic and diastolic blood pressure by 31 mm Hg. The patient was re-imaged with Xe CT and was found to have resolution of the ischemic changes within the left parietal occipital region. In this report, we present a case in which stable Xe CT was used to monitor the degree of cerebral perfusion and guide titration of antihypertensive therapy. Such brain perfusion monitoring may have helped to prevent infarction of our patient.

Measurement and analysis of brain deformation during neurosurgery.

Recent studies have shown that the surface of the brain is deformed by up to 20 mm after the skull is opened during neurosurgery, which could lead to substantial error in commercial image-guided surgery systems. We quantitatively analyze the intraoperative brain deformation of 24 subjects to investigate whether simple rules can describe or predict the deformation. Interventional magnetic resonance images acquired at the start and end of the procedure are registered nonrigidly to obtain deformation values throughout the brain. Deformation patterns are investigated quantitatively with respect to the location and magnitude of deformation, and to the distribution and principal direction of the displacements. We also measure the volume change of the lateral ventricles by manual segmentation. Our study indicates that brain shift occurs predominantly in the hemisphere ipsi-lateral to the craniotomy, and that there is more brain deformation during resection procedures than during biopsy or functional procedures. However, the brain deformation patterns are extremely complex in this group of subjects. This paper quantitatively demonstrates that brain deformation occurs not only at the surface, but also in deeper brain structure, and that the principal direction of displacement does not always correspond with the direction of gravity. Therefore, simple computational algorithms that utilize limited intraoperative information (e.g., brain surface shift) will not always accurately predict brain deformation at the lesion.

Influence of 1.5-Tesla intraoperative MR imaging on surgical decision making.

To determine the frequency that high-field magnetic resonance (MR) imaging sequences influenced surgical decision making during intraoperative MR-guided surgery. From January 1997 to February 2001, 346 MR-guided procedures were performed using a 1.5-Tesla MR system (NT-ACS, Philips Medical Systems). This system can perform functional MR imaging (fMRI), diffusion weighted imaging (DWI), MR spectroscopy (MRS), MR angiography (MRA), and MR venography (MRV) in addition to T1-weighted, T2-weighted, and turbo FLAIR (fluid-attenuated inversion recovery) imaging. FMRI was used to determine areas of brain activation for language, motor function, and memory. DWI was utilized after tumor resection to exclude cerebral ischemia or infarction. MRS was obtained to identify areas of elevated choline that were suspected to correlate with tumor presence. MRA and MRV localized vascular structures adjacent to tumors prior to resection. The intraoperative procedures performed included 140 brain biopsies of which 82 utilized a trajectory guide and prospective stereotaxy. MRS was used in 42 biopsies (30%), of which 29 had turbo spectroscopic imaging (TSI) and 21 had single voxel spectroscopy (SVS). In all biopsy cases, diagnostic tissue was obtained. There were 103 tumor resections of which 18 (17%) had MRS. Functional MRI was used in 17 cases; 3 biopsies (2%) and 14 planned resections (14%). Speech function was localized in 3 cases, memory function in 3, and motor function in 11. In one case where the motor function of the tongue was intimately involved with a low-grade glioma, resection was not attempted. DWI was used in less than 10% of tumor resections. MRA and MRV were performed in 3 (3%) and 2 (2%) of tumor resections, respectively. The imaging capabilities (i.e., fMRI, DWI, MRA, MRV) associated with high-field intraoperative MR influenced surgical decision making primarily for tumor resections. MRS influenced target selection during brain biopsy.

The roles of functional MRI in MR-guided neurosurgery in a combined 1.5 Tesla MR-operating room.

BACKGROUND AND PURPOSE: During MR-guided neurosurgical procedures performed in a combined 1.5 Tesla MR-operating room (MR-OR), we have successfully implemented and validated a functional MRI (fMRI) scheme for efficiently localizing eloquent functional areas and assessing their proximity to a lesion volume immediately prior to the craniotomy. METHODS: The fMRI examination consists of a dynamical blood oxygenation level dependent (BOLD) MR imaging technique and a task paradigm that is designed to activate the brain area of interest. The functional imaging technique was based on gradient-echo (GE) echo-planar imaging (EPI) (TR/TE = 2000-3000/40-50 msec). The motor task paradigm involves a periodic movement task, such as alternating between thumb and the other four fingers as a finger-tapping task, while the language involved a covert repeat of a series of words given as a task stimulus. While patient is performing the task, a dynamical fMRI was performed concurrently covering the volume of interest every 2 or 3 sec. Also, we have used a temporal series averaging (TSA) method for correcting the background drift in the raw fMRI signal, and developed a scheme for presenting fMRI results to neurosurgeons in an intuitive 3-dimensional volume-rendered display format. RESULTS: By using the fMRI scheme, we have successfully performed sixteen fMRI examinations immediately prior to neurosurgery in the combined MR-OR on the same surgical table to localize various eloquent functional areas of interests. TSA was successful in reducing the background drift in the fMRI time course data, and the 3-dimensional volume-rendered display was proven effective in presenting the resulting brain activations to neurosurgeons. More importantly, in three representative cases (one biopsy and two tumor resections) presented, the information provided by fMRI have indeed contributed significantly in making the optimal surgical decisions prior to craniotomy. CONCLUSIONS: Intra-operative fMRI can be an indispensable tool for determining the location of a neighboring eloquent functional area of concern in reference to a targeted lesion. Information provided by fMRI has helped in improving the outcome and clinician confidence of all surgeries performed.

Costs and benefits of intraoperative MR-guided brain tumor resection.

We retrospectively compared the costs and benefits of brain tumor resection in the conventional operating room (cOR) with the interventional magnetic resonance (iMR) suite from 1993-1998. Comparisons were made for adults (diagnosis-related group (DRG) 001) and children (DRG 003) for length of stay (LOS), hospital charges and payments, hospital total direct and indirect costs, readmission rates, repeat resection (RR) interval, and net health outcome. Statistical analysis was with ANOVA, Dunnett's, and Bonferroni tests. For DRG 001, iMR LOS (3.7 days (d)) was 54.9% shorter than for cOR (8.2 d) for first resections (FR) (P < 0.001) and RR (6.0 vs. 8.7 d (31.0%), P < 0.05). IMR hospital charges were 12.2% lower ($4063) for FR and 4.1% lower ($922) for RR than for cOR. Total iMR hospital costs were 14.4% lower ($3415) than for cOR for FR and 3.3% lower ($723) than costs for RR. Cost-to-charge ratio (c/c) for FR was 69.6% (iMR) and 71.4% (cOR) and for RR 70.9% (iMR) and 71.1% (cOR). For DRG 003, iMR LOS (4.5 d) was shorter than for cOR (14.1 d, P < 0.001) for FR and for RR (8.0 vs. 13.3 d). IMR hospital charges were 43.8% lower than for cOR for FR (P < 0.05) and RR. The iMR costs were lower for FR (46.4%, P < 0.01) and RR (44.7%) than cOR. IMR c/c was 71.4% and 74.8% for cOR. For RR, the iMR c/c was 72.8% and 73.9% for cOR. No RR have followed iMR surgery. COR RR rate was 20% in adults and 30% in children. The mean time from iMR surgery was 11.3 months in adults and 18.0 in children. For the cOR, the mean time to RR was 9.3 months in adults and 13.3 in children. This data suggests that iMR surgery improves net health outcomes by reduced LOS, reduced RR, and reduced hospital charges and costs.

Diffusion-weighted MR imaging findings in carbon monoxide poisoning.

Diffusion-weighted MR imaging (DWI) of two patients with carbon monoxide (CO) poisoning demonstrated white matter and cortical hyperintensities. In one patient, the changes on the FLAIR sequence were more subtle than those on DWI. The DWI abnormality in this patient represented true restriction. In the second patient, repeated exposure to CO caused restricted diffusion. DWI may be helpful for earlier identification of the changes of acute CO poisoning.

Perfusion MR neuroimaging in patients undergoing balloon test occlusion of the internal carotid artery.

BACKGROUND AND PURPOSE: We sought to investigate whether the combination of conventional, diffusion-weighted, and perfusion-weighted MR imaging increases the diagnostic accuracy of balloon test occlusion of the internal carotid artery. We describe perfusion anomalies and patterns of enhancement seen in areas of altered brain perfusion during MR-monitored temporary balloon occlusion of the internal carotid artery. METHODS: Nine patients underwent balloon occlusion testing under standard angiographic conditions with continuous clinical and EEG monitoring. One patient who failed the test by clinical criteria underwent an external carotid to internal carotid bypass operation, followed by a repeat balloon test occlusion, thereby bringing the total number of procedures to 10. Patients were further imaged at 1.5 T with perfusion- and diffusion-weighted imaging as well as with conventional noncontrast and contrast-enhanced turbo fluid-attenuated inversion recovery (FLAIR) and T1-weighted sequences. RESULTS: Seven of 10 patients who tolerated unilateral carotid test occlusion without adverse clinical neurologic or EEG changes exhibited delayed first-pass transit of contrast material through the affected cerebral hemisphere, indicative of altered perfusion without significant concurrent cerebral blood flow or blood volume changes. Four of these patients and both symptomatic patients showed pial or subarachnoid contrast staining in areas of altered perfusion without abnormalities on diffusion-weighted images. CONCLUSION: Our findings indicate that MR perfusion-weighted imaging is safe and easily accomplished in a high-field-strength magnet and that contrast-enhanced turboFLAIR imaging may provide clinically useful MR imaging evidence of abnormal cerebral blood flow and subclinical ischemia.