Diffusion-weighted MRI in cortical ischaemia

Correlation of serum S100B levels with brain magnetic resonance imaging abnormalities in children with status epilepticus

PURPOSE

To evaluate the association between elevated S100B levels with brain tissue damage seen in abnormalities of head magnetic resonance imaging (MRI; diffusion tensor imaging [DTI] sequence) in patients with status epilepticus (SE).

METHODS

An analytical observational study was conducted in children hospitalized at Dr Soetomo Hospital, Surabaya, from July to December 2016. The patients were divided into 2 groups: SE included all children with a history of SE; control included all children with febrile seizure. Blood samples of patients were drawn within 24 hours after admission. SE patients also underwent cranial MRI with additional DTI sequencing. The Mann-Whitney test and Spearman test were used for statistical analysis.

RESULTS

Fifty-three patients were enrolled the study. In the 24 children with SE who met the inclusion criteria, serum S100B and cranial MRI findings were assessed. Twenty-two children admitted with febrile seizures became the control group. Most patients were male (66.7%); the mean age was 35.8 months (standard deviation, 31.09). Mean S100B values of the SE group (3.430±0.141 μg/L) and the control group (2.998±0.572 μg/L) were significantly different (P<0.05). A significant difference was noted among each level of encephalopathy based on the cranial MRI results with serum S100B levels and the correlation was strongly positive with a coefficient value of 0.758 (P<0.001).

CONCLUSION

In SE patients, there is an increase of serum S100B levels within 24 hours after seizure, which has a strong positive correlation with brain damage seen in head MRI and DTI.

Nonconvulsive partial status epilepticus mimicking recurrent infarction revealed by diffusion-weighted and arterial spin labeling perfusion magnetic resonance images

"Non-convulsive" partial status epilepticus (SE) is an important pathologic condition that should be differentiated from cerebral infarction. Herein, we reported 2 patients who had partial SE associated with old infarction in the right parietal lobe. Each patient had 2 episodes of left hemiparesis and hemisensory disturbance without convulsion. On diffusion-weighted magnetic resonance images (DW-MRI), a hyperintense lesion was noted in the cortex around the old infarction lesion, and recurrent infarction was suspected. Although electroencephalography (EEG) failed to reveal ictal discharges or interictal paroxysmal activities in 3 of 4 episodes, perfusion images with arterial spin labeling (ASL) clearly demonstrated ictal hyperperfusion in the area corresponding to the cortical hyperintense lesion on DW-MRI. After appropriate anticonvulsant treatment based on the diagnosis of partial SE, clinical symptoms were completely improved. These data stress the importance of cortical hyperintensity on DW-MRI and ictal ASL hyperperfusion, even when SE cannot be determined from EEG.

Efficacy of diffusion-weighted magnetic resonance imaging performed before therapeutic hypothermia in predicting clinical outcome in comatose cardiopulmonary arrest survivors

AIM OF THE STUDY

To develop a clinically relevant and qualitative brain magnetic resonance imaging (MRI) scoring system for acute stage comatose cardiac arrest patients.

METHODS

Consecutive comatose post-cardiopulmonary arrest patients were prospectively enrolled. Routine brain MRI sequences were scored by two independent and blinded experts. Predefined brain regions were qualitatively scored on diffusion-weighted imaging (DWI) sequences according to the severity of the abnormality on a scale from 0 to 4. The mean score provided by the raters determined poor outcome defined under the Cerebral Performance Categories 3, 4, or 5. DWI scans were repeated after therapeutic hypothermia (TH). The same qualitative scoring system was applied and results were compared to the initial scores.

RESULTS

Out of 24 recruited patients, 19 with brain MRI scans were included. Of the 19 included patients, seven showed a good outcome at hospital discharge and 12 patients showed poor neurologic outcome. Median time from the arrest to the initial DWI was 166min (IQR 114-240min). At 100% specificity, the overall, cortex, and cortex plus deep grey nuclei scores predicted poor patient outcome with a sensitivity of 91.7-100% (95% CI). Follow-up DWI scans after TH showed worse results than initial scans.

CONCLUSION

A qualitative MRI scoring system effectively assessed the severity of hypoxic-ischaemic brain injury following cardiopulmonary arrest. The scoring system may provide useful prognostic information in comatose cardiopulmonary arrest patients.

Deafferentation in thalamic and pontine areas in severe traumatic brain injury

PURPOSE

Severe traumatic brain injury (TBI) is characterized mainly by diffuse axonal injuries (DAI). The cortico-subcortical disconnections induced by such fiber disruption play a central role in consciousness recovery. We hypothesized that these cortico-subcortical deafferentations inferred from diffusion MRI data could differentiate between TBI patients with favorable or unfavorable (death, vegetative state, or minimally conscious state) outcome one year after injury.

METHODS

Cortico-subcortical fiber density maps were derived by using probabilistic tractography from diffusion tensor imaging data acquired in 24 severe TBI patients and 9 healthy controls. These maps were compared between patients and controls as well as between patients with favorable (FO) and unfavorable (UFO) 1-year outcome to identify the thalamo-cortical and ponto-thalamo-cortical pathways involved in the maintenance of consciousness.

RESULTS

Thalamo-cortical and ponto-thalamo-cortical fiber density was significantly lower in TBI patients than in healthy controls. Comparing FO and UFO TBI patients showed thalamo-cortical deafferentation associated with unfavorable outcome for projections from ventral posterior and intermediate thalamic nuclei to the associative frontal, sensorimotor and associative temporal cortices. Specific ponto-thalamic deafferentation in projections from the upper dorsal pons (including the reticular formation) was also associated with unfavorable outcome.

CONCLUSION

Fiber density of cortico-subcortical pathways as measured from diffusion MRI tractography is a relevant candidate biomarker for early prediction of one-year favorable outcome in severe TBI.

Heterogeneity of radiological spectrum in tacrolimus-associated encephalopathy after lung transplantation

Background. Tacrolimus-associated encephalopathy (TAC-E) is usually described under the term of posterior reversible encephalopathy syndrome (PRES). However, a large amount of data has suggested that TAC-E is not a homogenous entity: indeed, TAC-E which is often presented with atypical and potentially misleading imaging characteristics does not always correspond to PRES. Objective. We aimed to identify the spectrum of brain MR imaging of TAC-E and discuss the underlying pathophysiological features. Methods. From September 2008 to October 2010, the neurological statuses of 45 patients, who underwent lung transplantation with TAC as posttransplantation immunosuppressive therapy, were regularly assessed in a prospective study. MRI was repeatedly performed, until recovery, in patients who developed central neurological symptoms. Results. Symptoms suggestive of encephalopathy occurred in five out of 45 patients (11.1%). According to our MRI study, two patients presented with reversible bilateral and relatively symmetric subcortical white matter edema with proximal vasospasms on MRA; however, three other patients were characterized by coexistence of two different lesions including laminar cortical infarcts with hemorrhagic transformation not typically found in PRES and reversible deep white matter edema, associated with distal vasospasms on MRA. Conclusions. It is considered that the mechanism of TAC-E would be more heterogenous than commonly perceived.

Hyperintense cortical signal on magnetic resonance imaging reflects focal leukocortical encephalitis and seizure risk in progressive multifocal leukoencephalopathy

OBJECTIVE

To determine the frequency of hyperintense cortical signal (HCS) on T1-weighted precontrast magnetic resonance (MR) images in progressive multifocal leukoencephalopathy (PML) patients, its association with seizure risk and immune reconstitution inflammatory syndrome (IRIS), and its pathologic correlate.

METHODS

We reviewed clinical data including seizure history, presence of IRIS, and MR imaging scans from PML patients evaluated at our institution between 2003 and 2012. Cases that were diagnosed either using cerebrospinal fluid JC virus (JCV) polymerase chain reaction, brain biopsy, or autopsy, and who had MR images available were included in the analysis (n=49). We characterized pathologic findings in areas of the brain that displayed HCS in 2 patients and compared them with isointense cortex in the same individuals.

RESULTS

Of 49 patients, 17 (34.7%) had seizures and 30 (61.2%) had HCS adjacent to subcortical PML lesions on MR images. Of the 17 PML patients with seizures, 15 (88.2%) had HCS compared with 15 of 32 (46.9%) patients without seizures (p=0.006). HCS was associated with seizure development with a relative risk of 4.75 (95% confidence interval=1.2-18.5, p=0.006). Of the 20 patients with IRIS, 16 (80.0%) had HCS compared with 14 of 29 (49.3%) patients without IRIS (p=0.04). On histological examination, HCS areas were associated with striking JCV-associated demyelination of cortical and subcortical U fibers, significant macrophage infiltration, and a pronounced reactive gliosis in the deep cortical layers.

INTERPRETATION

Seizures are a frequent complication in PML. HCS is associated with seizures and IRIS, and correlates histologically with JCV focal leukocortical encephalitis.

Metabolic changes in patients with aneurysmal subarachnoid hemorrhage apart from perfusion deficits: neuronal mitochondrial injury?

BACKGROUND AND PURPOSE

Neuronal damage in aSAH apart from perfusion deficits has been widely discussed. We aimed to test if cerebral injury occurs in aSAH independently from visible perfusion deficit by measuring cerebral metabolites in patients with aSAH without infarction or impaired perfusion.

MATERIALS AND METHODS

We performed 3T MR imaging including (1)H-MR spectroscopy, DWI, and MR perfusion in 58 patients with aSAH and 11 age-matched and sex-matched control patients with incidental aneurysm. We compared changes of NAA, Cho, Glx, Lac, and Cr between all patients with aSAH and controls, between patients with and without visible perfusion deficit or infarction and controls, and between patients with and without visible perfusion deficit or infarction by using the Wilcoxon signed-rank test.

RESULTS

We found that NAA significantly (P < .005) decreased in all patients with aSAH. Cho was significantly increased in all patients compared with controls (P < .05). In patients without impaired perfusion or infarction, Glx was significantly decreased compared with both controls (P = .005) and patients with impaired perfusion or infarction (P = .006).

CONCLUSIONS

The significant decrease of NAA and Glx in patients with aSAH but without impaired perfusion or infarction strongly suggests global metabolic changes independent from visible perfusion deficits that might reflect neuronal mitochondrial injury. Further, impaired perfusion in aSAH seems to induce additional metabolic changes from increasing neuronal stress that might, to some extent, mask the global metabolic changes.

Early diffusion-weighted magnetic resonance imaging in children after cardiac arrest may provide valuable prognostic information on clinical outcome

OBJECTIVE

We examined whether early diffusion-weighted magnetic resonance imaging (DW-MRI) abnormalities of the brain and variation of apparent diffusion coefficient (ADC) values can provide prognostic information on clinical outcome in children following cardiac arrest (CA).

DESIGN

Retrospective study.

SETTING

A 12-bed paediatric intensive care unit (PICU).

PATIENTS

Children aged between 1 month and 18 years who had DW-MRI with ADC measurement within the first week following CA. Neurological outcomes were assessed using the Pediatric Cerebral Performance Category Scale (PCPC). Differences between the favourable (PCPC ≤3) and unfavourable (PCPC ≥4) groups were analysed with regard to clinical data, electrophysiological patterns as well as qualitative and quantitative DW-MRI abnormalities.

RESULTS

Twenty children with a median age of 20 months (1.5-185) and a male/female sex ratio of 1.5 underwent DW-MRI after CA with a median delay of 3 days (1-7). Aetiologies of CA were (i) asphyxia (n = 10), (ii) haemodynamic (n = 5) or (iii) unknown (n = 5). With regard to DW-MRI findings, the unfavourable outcome group (n = 8) was associated with cerebral cortex (p = 0.02) and basal ganglia (p = 0.005) lesions, with a larger number of injured brain regions (p = 0.001) and a global decrease in measured ADC signal (p = 0.008). Normal DW-MRI (n = 5) was exclusively associated with the favourable outcome group (n = 12).

CONCLUSION

Qualitative, topographic and quantitative analysis of early DW-MRI with ADC measurement in children following CA may provide valuable prognostic information on neurological outcomes.

Cortical laminar necrosis in an infant with severe traumatic brain injury

Cortical laminar necrosis appears as hyperinense lesions with a laminar pattern on T1 weighted magnetic resonance (MR) imaging, without signs of hemorrhage or calcification on T2 weighted MR imaging or computed tomography. It has been reported to be associated with hypoxia, metabolic disturbances, drugs, and infections. We present a 12 month-old male infant who suffered diffuse brain injuries following car accident and showed laminar necrosis of cortex.

Decreased cortical thickness in central hypoventilation syndrome

Central hypoventilation syndrome (CHS) is a rare condition characterized by hypoventilation during sleep, reduced ventilatory responsiveness to CO(2) and O(2), impaired perception of air hunger, and autonomic abnormalities. Neural impairments accompany the condition, including structural injury, impaired cerebral autoregulation, and dysfunctional autonomic control. The hypoventilation may induce cortical hypoxic injury, additional to consequences of maldevelopment from PHOX2B mutations present in most CHS subjects. We assessed cortical injury in clinically diagnosed CHS using high-resolution magnetic resonance imaging scans, collected from 14 CHS (mean age ± standard deviation [SD] 17.7 ± 5.0 years; 6 female) and 29 control (mean age ± SD, 17.9 ± 4.3 years; 12 female) subjects. We measured group differences in mean cortical thickness and age-thickness correlations using FreeSurfer software, accounting for age and sex (0.1 false discovery rate). Reduced thickness in CHS appeared in the dorsomedial frontal cortex and anterior cingulate; medial prefrontal, parietal, and posterior cingulate cortices; the insular cortex; anterior and lateral temporal lobes; and mid- and accessory motor strips. Normal age-related cortical thinning in multiple regions did not appear in CHS. The cortical thinning may contribute to CHS cardiovascular and memory deficits and may impair affect and perception of breathlessness. Extensive axonal injury in CHS is paralleled by reduced cortical tissue and absence of normal developmental patterns.

A case of hypoglycemic brain injuries with cortical laminar necrosis

We report a case of 68-yr-old male who died from brain injuries following an episode of prolonged hypoglycemia. While exploring controversies surrounding magnetic resonance imaging (MRI) findings indicating the bad prognosis in patients with hypoglycemia-induced brain injuries, we here discuss interesting diffusion-MRI of hypoglycemic brain injuries and their prognostic importance focusing on laminar necrosis of the cerebral cortex.

Diffusion-weighted magnetic resonance imaging for predicting the clinical outcome of comatose survivors after cardiac arrest: a cohort study

INTRODUCTION

The aim of this study was to examine whether the patterns of diffusion-weighted imaging (DWI) abnormalities and quantitative regional apparent diffusion coefficient (ADC) values can predict the clinical outcome of comatose patients following cardiac arrest.

METHODS

Thirty-nine patients resuscitated from out-of-hospital cardiac arrest were prospectively investigated. Within five days of resuscitation, axial DWIs were obtained and ADC maps were generated using two 1.5-T magnetic resonance scanners. The neurological outcomes of the patients were assessed using the Glasgow Outcome Scale (GOS) score at three months after the cardiac arrest. The brain injuries were categorised into four patterns: normal, isolated cortical injury, isolated deep grey nuclei injury, and mixed injuries (cortex and deep grey nuclei). Twenty-three subjects with normal DWIs served as controls. The ADC and percent ADC values (the ADC percentage as compared to the control data from the corresponding region) were obtained in various regions of the brains. We analysed the differences between the favourable (GOS score 4 to 5) and unfavourable (GOS score 1 to 3) groups with regard to clinical data, the DWI abnormalities, and the ADC and percent ADC values.

RESULTS

The restricted diffusion abnormalities in the cerebral cortex, caudate nucleus, putamen and thalamus were significantly different between the favourable (n = 13) and unfavourable (n = 26) outcome groups. The cortical pattern of injury was seen in one patient (3%), the deep grey nuclei pattern in three patients (8%), the cortex and deep grey nuclei pattern in 21 patients (54%), and normal DWI findings in 14 patients (36%). The cortex and deep grey nuclei pattern was significantly associated with the unfavourable outcome (20 patients with unfavourable vs. 1 patient with favourable outcomes, P < 0.001). In the 22 patients with quantitative ADC analyses, severely reduced ADCs were noted in the unfavourable outcome group. The optimal cutoffs for the mean ADC and the percent ADC values determined by receiver operating characteristic (ROC) curve analysis in the cortex, caudate nucleus, putamen, and thalamus predicted the unfavourable outcome with sensitivities of 67 to 93% and a specificity of 100%.

CONCLUSIONS

The patterns of brain injury in early diffusion-weighted imaging (DWI) (less than or equal to five days after resuscitation) and the quantitative measurement of regional ADC may be useful for predicting the clinical outcome of comatose patients after cardiac arrest.

Meta-analysis of apparent diffusion coefficients in the newborn brain

Diffusion-weighted imaging and its quantitative apparent diffusion coefficient can assess severity in newborn hypoxic-ischemic injuries. A meta-analysis established normative values in term newborns, in comparison to those values in hypoxic-ischemic newborns with good versus poor outcomes. Measurements from 14 reports were stratified into three levels of increasing specificity: tissue type (gray matter, white matter, or cerebellum), tissue distribution (e.g., cortex or white-matter tracts), and anatomic structures (e.g., frontal white matter or posterior limb of the internal capsule). Normative apparent diffusion coefficients constituted white matter > gray matter = cerebellum, with lowest values in the posterior limb of the internal capsule and thalamus, and the highest in frontal and occipital white matter. Differences between normative and hypoxic-ischemic injury good-outcome groups were not evident. Values in the poor outcome group were significantly lower than normative data in white matter, gray matter, cortical gray matter, white matter tracts, posterior limb of the internal capsule, and cortical, frontal, and occipital white matter. Comparisons between injury groups found that coefficients were only significantly lower in the occipital cortex among poor outcomes. Coefficient values were lower in deep brain compared with cortical structures, reflecting tissue maturation and myelination. Differences between normative and hypoxic-ischemic injury poor-outcome groups suggest pathologies associated with neurologic sequelae. This meta-analysis provides the basis for normative apparent diffusion coefficient values in the newborn brain.

Usefulness of a 1.5 T MRI-compatible EEG electrode system for routine use in the intensive care unit of a tertiary care hospital

BACKGROUND

Continuous electroencephalogram (cEEG) recordings are being increasingly used in intensive care units (ICUs) to detect epileptic seizures and other changes. MRI scans can interrupt such recordings if the EEG electrodes need to be removed and important data can be missed.

METHODS

We retrospectively examined EEG recordings from ICU patients who underwent MRI scans, comparing those from patients with the MRI-compatible EEG electrodes with those who had to have the EEG electrodes removed before scanning. We also examined technical aspects of the recording and scalp abrasions in both groups.

RESULTS

Fourteen of 31 (45%) EEG recordings with the MRI-compatible electrode system in patients that underwent MRI scans between 03:00 p.m. and 07:00 a.m. (when technologists were not available) captured seizures. In contrast, all of the six EEG recordings with the MRI-incompatible electrode system in patients that underwent MRI scanning during the same interval were interrupted and had no data. Recording characteristics of the EEGs were comparable between the two groups and none had scalp abrasions.

CONCLUSION

A significant proportion of patients undergoing MRI scans with the MRI-compatible EEG electrodes had seizures that would have been missed if the MRI-incompatible EEG electrodes had been used.

Prognostic value of brain diffusion-weighted imaging after cardiac arrest

OBJECTIVE

Outcome prediction is challenging in comatose postcardiac arrest survivors. We assessed the feasibility and prognostic utility of brain diffusion-weighted magnetic resonance imaging (DWI) during the first week.

METHODS

Consecutive comatose postcardiac arrest patients were prospectively enrolled. AWI data of patients who met predefined specific prognostic criteria were used to determine distinguishing apparent diffusion coefficient (ADC) thresholds. Group 1 criteria were death at 6 months and absent motor response or absent pupillary reflexes or bilateral absent cortical responses at 72 hours or vegetative at 1 month. Group 2 criterion was survival at 6 months with a Glasgow Outcome Scale score of 4 or 5 (group 2A) or 3 (group 2B). The percentage of voxels below different ADC thresholds was calculated at 50 x 10(-6) mm(2)/sec intervals.

RESULTS

Overall, 86% of patients underwent DWI. Fifty-one patients with 62 brain DWIs were included. Forty patients met the specific prognostic criteria. The percentage of brain volume with an ADC value less than 650 to 700 x 10(-6)mm(2)/sec best differentiated between Group 1 and Groups 2A and 2B combined (p < 0.001), whereas the 400 to 450 x 10(-6)mm(2)/sec threshold best differentiated between Groups 2A and 2B (p = 0.003). The ideal time window for prognostication using DWI was between 49 and 108 hours after the arrest. When comparing DWI in this time window with the 72-hour neurological examination, DWI improved the sensitivity for predicting poor outcome by 38% while maintaining 100% specificity (p = 0.021).

INTERPRETATION

Quantitative DWI in comatose postcardiac arrest survivors holds promise as a prognostic adjunct.

Characteristics of liver on magnetic resonance diffusion-weighted imaging: Dynamic and image pathological investigation in rabbit liver VX-2 tumor model

AIM: To investigate dynamical and image pathological characteristics of the liver on magnetic resonance (MR) diffusion-weighted imaging (DWI) in the rabbit VX-2 tumor model.

METHODS: Forty New Zealand rabbits were included in the study and VX-2 tumor piece was implanted intrahepatically. Fifteen animals received two intrahepatic implantations while 25 had one intrahepatical implantation. DWI, T1- and T2-weighted of magnetic resonance imaging (MRI) were carried out on the 7th and the 14th d after implantation and DWI was conducted, respectively on the 21th d. Ten VX-2 tumor samples were studied pathologically.

RESULTS: The rate of lump detected by DWI, T1WI and T2WI was 78.7%, 10.7% and 53.5% (χ² = 32.61, P < 0.001) on the 7th d after implantation and 95.8%, 54.3% and 82.9% (χ² = 21.50, P < 0.001) on the 14th d. The signal of most VX-2 tumors on DWI was uniform and it was equal on the map of apparent diffusion coefficient (ADC). The signal of VX tumors did not decrease on the 7th d after implantation, most of them slowly growing during the week following implantation without significant cell dying within the tumor. VX-2 tumors grew increasingly within 14 d after implantation but the signal of most VX-2 tumors on DWI or on the map of ADC was uniform or uneven and ADC of VX tumors decreased obscurely or slightly because tumor necrosis was still not obvious. On the 21th d after implantation, the signal of most VX-2 tumors on DWI or on the map of ADC was uneven because tumor necrosis was evident and ADC of VX-2 tumor necrotic areas decreased. The areas of viable cells in VX-2 tumors manifested a high signal on DWI and a low signal on the map of ADC. The areas of dead cells or necrosis in VX-2 tumors manifested low signals on DWI and low, equal or high signals on the map of ADC but they manifested high signals on DWI and on the map of ADC at the same time when the areas of necrotic tumor became liquefied or cystic. The border of tumors on DWI appeared gradually distinct and internal signals of tumor became progressively uneven.

CONCLUSION: The manifestations of viable, necrotic and liquefied or cystic areas in VX-2 tumors on DWI are typical and DWI is of significant and potential values in clinical application in both the early detection and diagnosis of liver tumors.

Neuro-imaging of cerebral ischemic stroke

Major progress has recently been made in the neuro-imaging of stroke as a result of improvements in imaging hardware and software. Imaging may be based on either magnetic resonance imaging (MRI) or computed tomography (CT) techniques. Imaging should provide information on the entire vascular cervical and intracranial network, from the aortic arch to the circle of Willis. Equally, it should also give information on the viability of brain tissue and brain hemodynamics. CT has the advantage in the detection of acute hemorrhage whereas MRI offers more accurate pathophysiological information in the follow-up of patients.

Characteristics and pathological mechanism on magnetic resonance diffusion-weighted imaging after chemoembolization in rabbit liver VX-2 tumor model

AIM: To investigate dynamic characteristics and pathological mechanism of signal in rabbit VX-2 tumor model on diffusion-weighted imaging (DWI) after chemoembolization.

METHODS: Forty New Zealand rabbits were included in the study and forty-seven rabbit VX-2 tumor models were raised by implanting directly and intrahepatically after abdominal cavity opened. Forty VX-2 tumor models from them were divided into four groups. DWI was performed periodically and respectively for each group after chemoembolization. All VX-2 tumor samples of each group were studied by pathology. The distinction of VX-2 tumors on DWI was assessed by their apparent diffusion coefficient (ADC) values. The statistical significance between different time groups, different area groups or different b-value groups was calculated by using SPSS12.0 software.

RESULTS: Under b-value of 100 s/mm², ADC values were lowest at 16 h after chemoembolization in area of VX-2 tumor periphery, central, and normal liver parenchyma around tumor, but turned to increase with further elongation of chemoembolization treatment. The distinction of ADC between different time groups was significant respectively (F = 7.325, P < 0.001; F = 2.496, P < 0.048; F = 6.856, P < 0.001). Cellular edema in the area of VX-2 tumor periphery or normal liver parenchyma around tumor, increased quickly in sixteen h after chemoembolization but, from the 16th h to the 48th h, cellular edema in the area of normal liver parenchyma around tumor decreased gradually and that in the area of VX-2 tumor periphery decreased lightly at, and then increased continually. After chemoembolization, Cellular necrosis in the area of VX-2 tumor periphery was more significantly high than that before chemoembolization. The areas of dead cells in VX-2 tumors manifested low signal and high ADC value, while the areas of viable cells manifested high signal and low ADC value.

CONCLUSION: DWI is able to detect and differentiate tumor necrotic areas from viable cellular areas before and after chemoembolization. ADC of normal liver parenchyma and VX-2 tumor are influenced by intracellular edema, tissue cellular death and microcirculation disturbance after chemoembolization.

Focal laminar cortical infarcts following aneurysmal subarachnoid haemorrhage

INTRODUCTION

The aim of this prospective study was to analyse small band-like cortical infarcts after subarachnoid haemorrhage (SAH) using magnetic resonance imaging (MRI) with reference to additional digital subtraction angiography (DSA).

METHODS

In a 5-year period between January 2002 and January 2007 10 out of 188 patients with aneurysmal SAH were evaluated (one patient Hunt and Hess grade I, one patient grade II, four patients grade III, two patients grade IV, and two patients grade V). The imaging protocol included serially performed MRI with diffusion- and perfusion-weighted images (DWI/PWI) at three time points after aneurysm treatment, and cerebral vasospasm (CVS) was analysed on follow-up DSA on day 7+/-3 after SAH.

RESULTS

The lesions were located in the frontal lobe (n=10), in the insular cortex (n=3) and in the parietal lobe (n=1). The band-like infarcts occurred after a mean time interval of 5.8 days (range 3-10 days) and showed unexceptional adjacent thick sulcal clots. Seven out of ten patients with cortical infarcts had no or mild CVS, and in the remaining three patients DSA disclosed moderate (n=2) or severe (n=1) CVS.

CONCLUSION

The infarct pattern after aneurysmal SAH includes cortical band-like lesions. In contrast to territorial infarcts or lacunar infarcts in the white matter which develop as a result of moderate or severe proximal and/or distal vasospasm visible on angiography, the cortical band-like lesions adjacent to sulcal clots may also develop without evidence of macroscopic vasospasm, implying a vasospastic reaction of the most distal superficial and intraparenchymal vessels.

Cerebral cortical laminar necrosis on diffusion-weighted MRI in hypoglycaemic encephalopathy

BACKGROUND

Laminar necrosis of the cerebral cortex characterized neuropathologically by delayed selective neuronal necrosis occurs in hypoglycaemic encephalopathy and other brain diseases.

CASE REPORT

A 37-year-old male with insulin-treated Type 1 diabetes mellitus developed hypoglycaemic encephalopathy associated with respiratory failure. Brain diffusion-weighted MRI during the subacute period demonstrated high signals along the cerebral cortex. Brain single-photon emission computed tomography showed diffuse, severe cerebral hypoperfusion. The patient remained comatose and died 1 month later.

CONCLUSIONS

High signals along the cortical bands on diffusion-weighted MRI suggest cortical laminar necrosis, although a postmortem examination was unavailable. Sustained hypoglycaemic brain injury, possibly associated with respiratory hypoxia, may be the underlying mechanism.