T2-weighted Signal Changes Research Articles

Delayed myelopathy after remote C1-2 sublaminar wire fixation: illustrative case.

Atlantoaxial sublaminar wiring complications, both early and delayed, have been documented. However, delayed neurological compromise 27 years after successful fusion is a rare but possible occurrence. A 76-year-old male, who had undergone C1-2 sublaminar wire fusion for atlantoaxial instability in 1995, presented with symptoms of progressive right arm weakness, falls, and incontinence of bowel and bladder over a 1-week period. Initial imaging workup revealed bowing of the C1-2 sublaminar wires resulting in cervical spinal cord compression and T2-weighted signal changes. A C1-2 laminectomy was performed to remove the wires and decompress the spinal cord with improvement in the patient's neurological status. This rare case highlights the potential for delayed cervical myelopathy and cord compression from sublaminar wires, even after a successful fusion. In patients with a history of sublaminar wiring who experience new neurological deficits, it is essential to evaluate the hardware for migration.

Spinal Cord Signal Intensity Predicts Functional Outcomes in the Operative Management of Degenerative Cervical Myelopathy.

Prospective single institutional cohort study on degenerative cervical myelopathy (DCM) from 2009 to 2022. This study aims to assess the relationship among preoperative spinal cord signal change, postoperative signal change evolution, and functional outcome in patients undergoing surgery for DCM. There is conflicting evidence on whether spinal cord signal intensity influences functional outcomes in patients with DCM. This prospective study investigated 104 patients with DCM that underwent both preoperative and routine postoperative cervical spine magnetic resonance imaging (MRI) as part of a research protocol. Signal intensity/grade, modified Japanese Orthopedic Association (mJOA) scores, signal resolution, and patient demographics were assessed. Sixty-eight of the subjects were found to have abnormal T2 spinal cord signal intensity changes on their preoperative MRI. The total mean preoperative mJOA score was 13.6, increasing postoperatively to 16 (P < 0.001). The presence or absence of preoperative spinal cord signal change was not associated with the change in mJOA score or neurological recovery rate after surgery. Of the 68 patients with preoperative T2 signal change, 36 were found to have an improvement in the T2-weighted signal grade after surgery and 32 had no change in postoperative signal grade. The mean improvement in mJOA score (3.7) and neurological recovery rate (70.3%) was significantly higher in the patients with preoperative signal change whose postoperative MRI signal change grade improved by at least one point compared with those that did not (2.0, 50.5%), (P < 0.001, P < 0.003). The presence of preoperative T2-weighted signal change was associated with lower preoperative mJOA scores, but no change in mJOA after surgery or postoperative neurological recovery rate. However, improvement in T2-weighted spinal cord signal grade on postoperative MRI was significantly associated with a degree of neurological improvement after surgery.

Influence of clinical and radiological parameters on the likelihood of neurological improvement after surgery for degenerative cervical myelopathy.

Degenerative cervical myelopathy (DCM) is routinely treated with surgical decompression, but disparate postoperative outcomes are frequently observed, ranging from complete neurological recovery to persistent decline. Although numerous clinical and radiological factors have been independently associated with failure to improve, the relative impact of these proposed risk factors remains obscure. In this study, the authors assess the combined role of clinical and radiographic parameters in contributing to failure to attain neurological improvement after surgery. A consecutive series of patients who underwent surgery for DCM between July 2013 and August 2018 at a single institution was identified from a prospectively maintained database. Retrospective chart review was undertaken to record perioperative clinical and radiographic parameters. Failure to improve on the last follow-up evaluation after surgery, defined as a change in modified Japanese Orthopaedic Association (mJOA) score less than 2, was the primary outcome in univariate and multivariate analyses. The authors included 183 patients in the final cohort. In total, 109 (59.6%) patients improved (i.e., responders with ΔmJOA score ≥ 2) after surgery and 74 (40.4%) were nonresponders with ΔmJOA score < 2. Baseline demographic variables and comorbidity rates were similar, whereas baseline Nurick score was the only clinical variable that differed between responders and nonresponders (2.7 vs 3.0, p = 0.02). In contrast, several preoperative radiographic variables differed between the groups, including presence and degree of cervical kyphosis, number of levels with bidirectional cord compression, presence and number of levels with T2-weighted signal change, intramedullary lesion (IML) length, Torg ratio, and both narrowest spinal canal and cord diameter. On multivariate analysis, preoperative degree of kyphosis at C2-7 (OR 1.19, p = 0.004), number of levels with bidirectional compression (OR 1.83, p = 0.003), and IML length (OR 1.14, p < 0.001) demonstrated the highest predictive power for nonresponse (area under the receiver operating characteristic curve 0.818). A risk factor point system that predicted failure of improvement was derived by incorporating these 3 variables. When a large spectrum of both clinical and radiographic variables is considered, the degree of cervical kyphosis, number of levels with bidirectional compression, and IML length are the most predictive of nonresponse after surgery for DCM. Assessment of these radiographic factors can help guide surgical decision-making and more appropriately stratify patients in clinical trials.

Microsurgical Treatment of Foramen Magnum Cognard Type V Dural Arteriovenous Fistula: 2-Dimensional Operative Video.

Cognard type V dural fistulas represent a rare and unique entity, and present clinically with myelopathy. They are frequently located around the foramen magnum and are most commonly fed by dural branches of the vertebral and external carotid artery. Detection requires meticulous angiography to define the angioarchitecture of the fistula, which in turn defines the treatment modality. We present the case of a 63 yr old woman, after informed consent was obtained, with prolonged, severe and progressive lower extremity myelopathy for 6 yr, with T2-weighted signal changes in the thoracic spinal cord on magnetic resonance imaging (MRI). Cervical MRI was unremarkable. Following computed tomography (CT), angiography of the spinal canal that revealed tortuous and dilated veins on the thoracic spinal cord surface, catheter angiography was performed. This demonstrated a fistula in relation to a dural branch of left vertebral artery with a characteristic single draining vein coursing caudally to the thoracic level, with delayed outflow suggestive of venous hypertension. Given the fact that the dural feeder was tortuous and relatively small, thus, precluding distal microcatheter access, and with presence of a single accessible draining vein, microsurgical treatment was preferred. Following a midline suboccipital craniotomy in prone position, a limited vertical dural opening was performed. Careful microsurgical arachnoid dissection revealed the arterialized draining vein with the aid of Indocyanine Green angiography. The draining vein was clipped, coagulated, and disconnected. Postoperative recovery was uneventful and the patient is undergoing rehabilitation therapy. Follow-up angiography showed complete elimination of the fistula. Salient teaching points are narrated at conclusion.

Stereotactic-Guided Dilatable Endoscopic Port Surgery for Deep-Seated Brain Tumors: Technical Report with Comparative Case Series Analysis

Deep-seated brain tumors are often best treated by primary surgical excision. Traditional microsurgical techniques can cause retraction injury and require extensive brain dissection. To mitigate this risk, stereotactic-guided tubular retractors were developed; however, the risk of shear injury remains. We created a stereotactic-guided dilatable port system to create a corridor for deep brain tumor surgery along the trajectory of a brain needle to minimize iatrogenic brain injury. Of the 8 included patients (6 colloid cysts, 1 metastasis, 1 intraventricular meningioma), 5 had undergone frameless and 3 frame-based stereotactic targeting. We used a tans-sulcal trajectory and a 2.6-mm stereotactic needle. At the target depth, the cannula was removed and the balloon inflated to 14 mm. The balloon was deflated and removed before placing the port. Pre- and 3-month postoperative magnetic resonance imaging scans were used to measure the T2-weighted signal change and residual cannulation defect. These patients were compared with a case-matched standard endoscopic port surgery cohort. All patients had undergone total lesional resection without new neurologic deficits. Patients undergoing dilatable endoscopic port surgery (DEPS) had significantly smaller residual cannulation defects (P < 0.05) but no significant differences in postoperative T2-weighted signal changes or diffusion restriction volumes at 3 months postoperatively (P > 0.05). DEPS might be a safe alternative to standard endoscopic port surgery or microsurgery for deep-seated brain tumors. The degree of iatrogenic injury using DEPS, as determined by magnetic resonance imaging analysis, might be equivalent to or less than that with standard port surgery techniques, although larger sample sizes are needed for validation.

Extraintestinal Manifestation of Celiac Disease: Gluten Ataxia

2570_A Figure 1. Interval progression of MRI T2 weighted signal changes seen on FLAIR sequence from presentation (A) with basal ganglia hyperintensities (upper panel) and diffuse cerebellar hyperintensities outlining the dentate nucleus (lower panel). After treatment, four months from onset (B) and nine months from onset (C) T2 FLAIR images demonstrate a reduction in basal ganglia hyperintensities with patchy cerebellar changes.Celiac disease is classically associated with gastrointestinal symptoms of malabsorption, diarrhea and weight loss. A subset of patients however can present with extraintestinal symptoms. Gluten ataxia is a neurological manifestation of celiac disease that can present with or without gastrointestinal symptoms. A 46 year old woman with no significant past medical history presents with ataxia and dysarthria. She developed slurring of speech and ataxia that progressively worsened within a 1 month period. This was preceded by 6 weeks of nausea and dizziness that self resolved. At presentation, she had double vision, weakness in the left upper extremity, anorexia, and a 30 lb weight loss. There was no fever, headache, behavioral change, dysphagia, vomiting, rash, or history of tick bites. On exam, she had mild dysarthria, mild left upper extremity weakness and hyperreflexia with a positive left Babinski sign, truncal ataxia, dysmetria, dysdiadochokinesia, positive Romberg sign and broad based gait. Her abdominal exam was normal and no rashes were noted on skin exam. MRI head with/without contrast showed non-enhancing T2 hyperintensities involving bilateral cerebral and cerebellar hemisphere as well as brainstem. Lumbar puncture showed opening pressure 210, glucose 54, protein 72, total nucleated cell 31 (95% lymphocyte), and 15 oligoclonal bands. Extensive CSF infectious serology was negative. CSF cytology was negative for malignant cells. CJD RT Quic was negative. IgA tissue transglutaminase was elevated at 10.5. Antiendomysial antibody was positive with titer of 1:20. EGD showed scalloped duodenum with duodenal biopsies showing villous atrophy, intraepithelial lymphocytosis, and crypt hyperplasia.2570_B Figure 2. EGD of the duodenum showing abnormal and scalloped mucosaThe patient was treated with a 12 week steroid taper beginning with 5 days of methylprednisolone 1 g daily. She was recommended to follow a strict gluten free diet. At her 3 month follow up, MRI head showed improvement in T2 hyperintensities and IgA tissue transglutaminase was <1.2. Her symptoms had nearly all resolved. Gluten ataxia often presents in middle-age individuals and can be of gradual onset or rapidly progressive. It commonly manifests as gait ataxia, limb ataxia, nystagmus, and dysarthria. The mainstay treatment for gluten ataxia is a gluten free diet. It is important to consider gluten ataxia and testing for celiac disease in patients presenting with cerebellar ataxia. A delay in treatment can result in progression of disease and irreversible symptoms.

Post-operative paediatric cerebellar mutism syndrome: time to move beyond structural MRI

PurposeTo determine the value of structural magnetic resonance imaging (MRI) in predicting post-operative paediatric cerebellar mutism syndrome (pCMS) in children undergoing surgical treatment for medulloblastoma.MethodsRetrospective cohort study design. Electronic/paper case note review of all children with medulloblastoma presenting to Great Ormond Street Hospital between 2003 and 2013. The diagnosis of pCMS was established through a scoring system incorporating mutism, ataxia, behavioural disturbance and cranial nerve deficits. MRI scans performed at three time points were assessed by neuroradiologists blinded to the diagnosis of pCMS.ResultsOf 56 children included, 12 (21.4%) developed pCMS as judged by a core symptom of mutism. pCMS was more common in those aged 5 or younger. There was no statistically significant difference in pre-operative distortion or signal change of the dentate or red nuclei or superior cerebellar peduncles (SCPs) between those who did and did not develop pCMS. In both early (median 5 days) and late (median 31 months) post-operative scans, T2-weighted signal change in SCPs was more common in the pCMS group (p = 0.040 and 0.046 respectively). Late scans also showed statistically significant signal change in the dentate nuclei (p = 0.024).ConclusionsThe development of pCMS could not be linked to any observable changes on pre-operative structural MRI scans. Post-operative T2-weighted signal change in the SCPs and dentate nuclei underlines the role of cerebellar efferent injury in pCMS. Further research using advanced quantitative MRI sequences is warranted given the inability of conventional pre-surgical MRI to predict pCMS.

The Relationship Between MRI Signal Intensity Changes, Clinical Presentation, and Surgical Outcome in Degenerative Cervical Myelopathy: Analysis of a Global Cohort.

Retrospective analysis of prospective data. To assess the relationship between MRI signal intensity changes, clinical presentation, and surgical outcome in degenerative cervical myelopathy (DCM). Several studies have sought to assess the extent of spinal cord dysfunction and the potential for postoperative neurological recovery through the evaluation of spinal cord signal change on T2-weighted (T2WI) and T1-weighted images (T1WI). There remains ambiguity if T2WI and T1WI signal changes (1) relate to baseline severity, and (2) predict neurological recovery after surgical treatment. Four hundred nineteen MRIs from two prospective multicenter studies were examined. Images were assessed for the presence, levels, and location of spinal cord signal intensity changes and compared with clinical data. Signal changes were also evaluated for the prediction of 2-year postoperative outcome using mJOA parameters. MRIs were categorized by T1WI and T2WI signal change: no signal change (28.9%), T2WI hyperintensity-only (T2WI-only, 51.8%), and T2WI-hyperintensity and T1WI-hypointensity (T1WI+T2WI, 19.3%). T2WI-hyperintensity was present at multiple levels in 27% of patients overall. Baseline severity increased from no signal change to T2WI-only to T2WI+T1WI (P < 0.0001), and there was an incremental increase in the frequency of signs/symptoms. There were no differences in outcomes between no signal change and T2WI-only groups. The presence of T1WI-hypointensity correlated with reduced recovery ratio (P = 0.03) and likelihood of an optimal surgical outcome (P = 0.005), adjusting for baseline mJOA. A greater number of T2WI-hyperintensity levels was also associated with worse baseline severity (P < 0.0001) and recovery ratio (P = 0.001). This analysis of a global cohort of DCM patients shows a stepwise trend toward increasing impairment from no signal change to T2WI-hypertensity to T1WI-hypointensity. T1WI signal change indicates more permanent injury, portending decreased functional recovery. T2WI-hyperintensity alone does not predict outcomes. Multiple levels of T2WI-hyperintensity suggest additional tissue injury, correlating with worse clinical impairment and recovery potential. 2.

Metabolic Imaging Using Proton Magnetic Spectroscopy as a Predictor of Outcome After Surgery for Cervical Spondylotic Myelopathy.

A single-center magnetic resonance spectroscopy (MRS) imaging and surgical outcome study involving 16 patients with cervical spondylotic myelopathy (CSM). In the present study, we assess the utility of MRS to quantify metabolic changes within the spinal cord and predict surgical outcome in CSM patients. MRS is an advanced spinal imaging modality that can provide pertinent metabolic and biochemical information regarding spinal cord function. Previous studies have demonstrated significant abnormalities in specific cellular metabolite concentrations in CSM patients. Sixteen patients with CSM were evaluated. Single voxel MRS was performed in the cervical cord. N-acetyl-aspartate (NAA) and choline metabolite concentration ratios with respect to creatine were quantified, as well as the presence or absence of a lactate peak. The modified Japanese Orthopaedic Association (mJOA) scale was used as the functional assessment measure. Correlation of MRS metabolites with change in mJOA score was performed. The mean follow-up time was 19 months. There was a statistically significant improvement between mean preoperative and postoperative mJOA score after surgery (P<0.0001). The NAA/Cr ratio demonstrated a significant relationship to the change in mJOA score after surgery (P=0.0479; R=0.2513). The Cho/NAA ratio demonstrated an even stronger correlation with the change in mJOA score after surgery (P=0.0065; R=0.4219). Neither the Cho/Cr ratio, nor the presence of a lactate peak or T2-weighted signal change was significantly correlated with change in mJOA score after surgery. MRS is a novel, noninvasive imaging modality that provides pertinent information regarding spinal cord cellular and metabolic function. In a cohort of operatively treated CSM patients, the NAA/Cr and Cho/NAA ratios were predictive of neurological outcome, as both were significantly associated with change in mJOA score after surgery.

Quantitative characterization of the imaging limits of diffuse low-grade oligodendrogliomas

Supratentorial diffuse low-grade gliomas in adults extend beyond maximal visible MRI-defined abnormalities, and a gap exists between the imaging signal changes and the actual tumor margins. Direct quantitative comparisons between imaging and histological analyses are lacking to date. However, they are of the utmost importance if one wishes to develop realistic models for diffuse glioma growth. In this study, we quantitatively compared the cell concentration and the edema fraction from human histological biopsy samples (BSs) performed inside and outside imaging abnormalities during serial imaging-based stereotactic biopsy of diffuse low-grade gliomas. The cell concentration was significantly higher in BSs located inside (1189 ± 378 cell/mm(2)) than outside (740 ± 124 cell/mm(2)) MRI-defined abnormalities (P = .0003). The edema fraction was significantly higher in BSs located inside (mean, 45% ± 23%) than outside (mean, 5 %± 9%) MRI-defined abnormalities (P < .0001). At borders of the MRI-defined abnormalities, 20% of the tissue surface area was occupied by edema and only 3% by tumor cells. The cycling cell concentration was significantly higher in BSs located inside (10 ± 12 cell/mm(2)), compared with outside (0.5 ± 0.9 cell/mm(2)), MRI-defined abnormalities (P = .0001). We showed that the margins of T2-weighted signal changes are mainly correlated with the edema fraction. In 62.5% of patients, the cycling tumor cell fraction (defined as the ratio of the cycling tumor cell concentration to the total number of tumor cells) was higher at the limits of the MRI-defined abnormalities than closer to the center of the tumor. In the remaining patients, the cycling tumor cell fraction increased towards the center of the tumor.

Diffusion weighted imaging with trace diffusion weighted imaging, the apparent diffusion coefficient and exponential images in the diagnosis of spinal cord infarction

A 73-year-old man, with a history of hypertension and left supraclavicular fossa arteriovenous malformation with multiple previous uncomplicated vessel embolisation procedures, presented with acute spastic quadriparesis and urinary retention following upper limb angiography and embolisation. There was no evidence of preceding infection or neurological disease prior to the event. Cerebrospinal fluid analysis was unremarkable. MRI of the cervical spine with a 1.5 Tesla magnet performed 13hours from symptom onset revealed bilateral paramedian intramedullary T2-weighted signal change without gadolinium enhancement limited to the grey matter with corresponding diffusion restriction extending from C5–6 down to the mid-T1. The diagnosis of cervical spinal cord infarction (SCI) was made and the patient was given regular aspirin and atorvastatin. On follow-up at 3months, there was modest improvement with respect to his quadriparesis and was walking unaided. An extensive literature review on the role of MRI in SCI is discussed.

The Diagnosis of Spinal Dural Arteriovenous Fistulas

Retrospective consecutive case series. To review and analyze clinical presentations and radiological imaging of 326 consecutive patients with spinal dural arteriovenous fistula (SDAVF) from 2 institutions. The clinical presentations of SDAVF are nonspecific. Patients may be initially diagnosed with other spinal diseases. Magnetic resonance imaging (MRI) can reveal spinal cord changes associated with the disorder, but neurosurgeons often overlook these changes. From 1989 to 2009, 326 patients were diagnosed with SDAVF and treated at Qilu Hospital of Shandong University and the Xuanwu Hospital of the Capital University of Medical Sciences. We retrospectively reviewed the clinical records and radiological images of all patients, and collected and analyzed the related data. Two hundred eighty-two males and 44 females (male/female ratio 6.4:1; mean age, 53.9 yr; SD, 12.1) were included in the study. Fistulas were located at the T7 spinal segment (41, 12.6%), but were more typically found at T5 to L5 (273, 82.5%). The most common initial symptoms were lower extremity weakness (234, 71.8%), sensory disturbance (229, 70.2%), and sphincter disturbance (87, 26.7%). These percentages increased to, 85.6%, 80.8%, and 52.5%, respectively, until patients were properly diagnosed. The mean diagnostic time to SDAVF was 19.9 months (SD, 25.2). Two major changes noted on magnetic resonance images were intramedullary T2-weighted signal hyperintensity (284, 87.1%) and perimedullary dilated vessels (251, 77%). Fistulas were often located outside of the vertebral segments of T2-weighted signal change (P = 0.005). Magnetic resonance angiography and computed tomography angiography of 33 (71.7%) patients revealed perimedullary dilated vessels and precisely located fistulas in 19 (41.3%) patients. Magnetic resonance angiography and computed tomography angiography studies of the perimedullary vessels also led to identification of a second fistula through angiography. Degenerative disc disease and myelitis were the most common misdiagnoses, and the patients were often treated incorrectly. "Worsening" and "symptoms combination" are progression characteristics of SDAVF. Patients should undergo spinal magnetic resonance imaging when they are first suspected to have SDAVF. Magnetic resonance angiography and computed tomography angiography as noninvasive angiography are helpful for diagnosis.

Radiological and histological changes following cerebral venous sinus thrombosis in a rat model

Cerebral venous sinus thrombosis (CVST) is an important cause of stroke in young especially after pregnancy. We induced CVST in rat by topical application of ferric chloride over the exposed superior sagittal sinus (SSS) and pathological changes were monitored on days 1, 2 and 7. Thrombus weight was estimated and H&E staining was performed for comparison with MRI data. T2 weighted signal changes were present in all the study group rats. T2 hyper intensity decreased over the time. In study group, the apparent diffusion coefficient (ADC) was decreased by 31.94% on day 1 compared to the controls. There was 15.5% increase in the ADC value on day 2 compared to day 1 which reached almost equal to control value on day 7. On histological evaluation, neuronal necrosis and cellular infiltration were observed in cortical region after thrombosis. The early decrease in ADC could be attributed to cytotoxic edema that precedes vasogenic edema indicated by normalization of ADC and a decreased T2 hyper intensity. In conclusion, ferric chloride induced CVST in the rat produces cytotoxic edema in early stage followed by vasogenic edema which is related to recanalization of the superior sagittal sinus.

Diffusion and perfusion imaging in subacute neurotoxicity following high-dose intravenous methotrexate

Methotrexate (MTX) is a widely used chemotherapeutic agent that can cause acute, subacute, and chronic neurological complications. Subacute MTX neurotoxicity is manifest by abrupt onset of focal cerebral dysfunction occurring days to weeks after MTX administration, usually in children. We describe the neuroimaging features of an adult patient with primary CNS lymphoma who presented with transient aphasia and right hemiparesis 12 days after receiving intravenous high-dose MTX (8 g/m2) chemotherapy. Imaging within 1 h of symptom onset showed bilateral symmetrical restricted diffusion involving white matter of the cerebral hemispheres. CT angiogram and dynamic susceptibility MRI showed no evidence of vasospasm or perfusion defect. MRI five days later showed near-complete resolution of the abnormalities. MRI 3(1/2) months later showed normal diffusion but new hyperintense T2-weighted signal changes in the subcortical white matter corresponding to previous areas of restricted diffusion. The absence of vascular or perfusion abnormalities suggests that transient cytotoxic edema in white matter may explain the syndrome of subacute MTX neurotoxicity.

Proton Magnetic Resonance Spectroscopic Imaging Integrated into Image-guided Surgery: Correlation to Standard Magnetic Resonance Imaging and Tumor Cell Density

In this study, we attempted to improve the delineation of the infiltration zone in gliomas using proton magnetic resonance spectroscopic imaging (1H MRSI). In conventional magnetic resonance imaging (MRI), the boundaries of gliomas sometimes are underestimated. 1H MRSI is a noninvasive tool that can be used to investigate the spatial distribution of metabolic changes in brain lesions. The purpose was to correlate tumor cell density from histopathological specimens with metabolic levels and the coregistered metabolic maps. We developed a method to integrate spectroscopic data depicted as metabolic maps of biochemically pathological tissue into frameless stereotaxy. In seven patients harboring gliomas, we performed 1H MRSI with high spatial resolution and evaluated the spectral data. An algorithm was developed for user-independent calculation of pathological voxels and for visualization as metabolic maps. These maps were integrated into a three-dimensional MRI data set used for frameless stereotaxy. Stereotactic biopsies were taken from three different areas in and around the tumor involving the maximum pathological change, the border zone, and an area from outside the spectroscopically suspicious area. These specimens were correlated to the exact voxel positions in the stereotactic image space and evaluated histopathologically. In all cases, the implementation of the metabolic maps into frameless stereotaxy was successful, and stereotactic biopsies were acquired by use of the spectral data. A relation could be demonstrated between the metabolic changes and tumor cell density ranging from 60 to 100% in the maximum pathological area to 5 to 15% in the border zone. Interestingly, the tumor areas defined by the metabolic maps and histopathologically confirmed by biopsy exceeded the T2-weighted signal change in all cases, ranging from 6 to 32% in the examined volume. Our preliminary data suggest that 1H MRSI may be useful in combination with frameless stereotaxy to define more exactly the tumor infiltration zone in glioma surgery compared with conventional anatomic MRI alone.

Ex vivo MR microimaging of neuronal damage after kainate‐induced status epilepticus in rat: Correlation with quantitative histology

The present study was designed to investigate whether T2-weighted signal changes obtained by microimaging of paraformaldehyde-fixed brain correlate with the histologically quantified damage in a model of status epilepticus (SE) induced by kainic acid in the rat. Animals were killed at several time points up to 8 weeks after a single intraperitoneal kainate (KA) injection (9 mg/kg). Perfusion-fixed brains were embedded in gelatin for MR microimaging at 9.4T. After the MRI analysis, the gelatin was removed and the brains were cryoprotected and processed for quantitative histology. Severity of neuronal damage and gliosis were assessed from thionin-stained serial sections. Correlative analysis of microimaging and histology data was done in the hippocampus, amygdala, parietal rhinal cortex (PaRH), piriform cortex (Pir), and entorhinal cortex. The relative signal intensities in T2-weighted images correlate with the severity of neuronal damage in the matched histological sections (correlation coefficients of 0.752–0.826). Our data show that MR microimaging ex vivo detects the degree of neuronal damage and its anatomical distribution after KA-induced SE, thus providing a useful tool for detecting the dynamics of progressive neuronal damage after prolonged seizures. Magn Reson Med 46:946–954, 2001. © 2001 Wiley-Liss, Inc.