Sanjay Behari

Comparative Evaluation of Fungal, Tubercular, and Pyogenic Brain Abscesses with Conventional and Diffusion MR Imaging and Proton MR Spectroscopy

BACKGROUND AND PURPOSE: It is difficult to differentiate the cause of brain abscesses with the use of CT and MR imaging. We did a comparative evaluation of pyogenic, tubercular, and fungal brain abscesses by using conventional, diffusion-weighted imaging (DWI), and proton MR spectroscopy (PMRS) with an aim to define the unique features that may differentiate among the pyogenic, tubercular, and fungal brain abscesses. MATERIALS AND METHODS: We performed a retrospective analysis on 110 patients with surgically proved brain abscesses. Imaging studies included T2, T1, postcontrast T1, DWI, and PMRS. Apparent diffusion coefficient (ADC) of the wall and cavity of the abscesses were quantified. The morphologic, physiologic, and metabolite features of pyogenic (n = 91), tubercular (n = 11), and fungal (n = 8) abscesses were compared. RESULTS: The pyogenic abscesses had smooth (55/91) and lobulated (36/91) walls, whereas the tubercular abscesses had smooth (4/11), lobulated (6/11), or crenated walls (1/11) with no intracavitary projections. The fungal abscesses showed irregular walls (lobulated 4/8, crenated 4/8) with intracavitary projections (8/8). The wall as well as the cavity showed low ADC in the pyogenic and tubercular abscesses. In the fungal abscesses, the wall and projections showed low ADC (8/8); however, the cavity itself showed high ADC (8/8). PMRS showed cytosolic amino acids (89/91), acetate (25/91), and succinate (18/91) in the pyogenic abscesses, whereas lipid/lactate (11/11) was seen in the tubercular abscesses. The fungal abscesses showed lipid (4/8), lactate (7/8), amino acids (4/8), and multiple peaks between 3.6 and 3.8 ppm assigned to trehalose (5/8). CONCLUSION: Based on the morphologic, ADC, and metabolite information, it may be possible to differentiate among the pyogenic, tubercular, and fungal brain abscesses.

Role of Diffusion-weighted Imaging and In Vivo Proton Magnetic Resonance Spectroscopy in the Differential Diagnosis of Ring-enhancing Intracranial Cystic Mass Lesions

Objectives: Proton magnetic resonance spectroscopy (PMRS) and diffusion-weighted imaging (DWI) were compared to determine which technique is more effective in the differential diagnosis of cystic intraparenchymal ring-enhancing lesions with variable perifocal edema. Methods: Fifty-two patients (abscesses [n = 29], tumor cysts [n = 20], and benign cysts [n = 3]) formed the basis for comparative evaluation in this study. The criteria for abscess diagnosis were apparent diffusion coefficient (ADC) values less than 0.9 ± 1.3 × 10−3 mm2/s and presence of lactate cytosolic amino acids (AAs) with/without succinate, acetate, alanine, and glycine on PMRS. Criteria for nonabscess cyst identification were ADC values of 1.7–3.8 × 10−3 mm2/s and presence of lactate and choline on PMRS. On the basis of these criteria, patients were categorized into abscess (n = 29) and nonabscess (n = 23) groups. Sensitivity and specificity of PMRS and DWI with respect to the final diagnosis were calculated based on the efficacy of these techniques. Results: Apparent diffusion coefficient values in 21 patients with abscesses were observed within the range of defined criteria, whereas in 8 patients, ADC values were beyond the range of defined criteria. Lactate and AAs with or without other metabolites were observed in 25 of 29 cases of abscesses on PMRS. In the nonabscess group, ADC values of cystic lesions in all patients were consistent with respect to the defined criteria. Only lactate was seen in 14 of 23 patients, whereas both lactate and choline were visible in 6 patients. In 3 patients with neurocysticercosis, AAs (n = 2), lactate (n = 3), acetate (n = 1), succinate (n = 3), choline (n = 2), and alanine (n = 3) were seen. The sensitivity of DWI and PMRS for differentiation of brain abscess from nonbrain abscess was 0.72 and 0.96, respectively, whereas the specificity was 1 for both techniques. Conclusion: Demonstration of restricted diffusion on DWI with reduced ADC is highly suggestive of brain abscess; however, in the absence of restriction, PMRS is mandatory to distinguish brain abscesses from cystic tumors.

Idiopathic Hypertrophic Cranial Pachymeningitis: Clinicoradiological Spectrum and Therapeutic Options

OBJECTIVE Idiopathic hypertrophic cranial pachymeningitis is a rare disease, of undetermined pathogenesis, that is characterized by inflammation and fibrosis of the dura mater. METHODS We encountered six patients with idiopathic hypertrophic cranial pachymeningitis and analyzed their clinical presentations, radiological findings, and treatment. RESULTS In the six patients, the main manifestations were cranial nerve palsies and headache. Three associations were present, namely optic neuropathy, Tolosa-Hunt syndrome, and diabetes insipidus. Gadolinium-enhanced magnetic resonance imaging was diagnostic, showing intense dural enhancement in a linear or nodular pattern. The responses to corticosteroid therapy were better for patients who exhibited linear, rather than nodular, dural enhancement. For one patient, surgical decompression of the superior orbital fissure provided lasting relief. The course of the disease followed one of three patterns, i.e., sustained remission, relapse with corticosteroid independence, or relapse with corticosteroid dependence. Pulse corticosteroid therapy provided significant relief, while reducing the daily corticosteroid requirement and avoiding side effects, for a corticosteroid-dependent relapsing patient. CONCLUSION Idiopathic hypertrophic cranial pachymeningitis exhibits varied clinical courses. It is important to prevent irreversible cranial neuropathy during the active phase of the disease, using daily administration of corticosteroids, pulse corticosteroid therapy, or surgical decompression.

Discriminant analysis to classify glioma grading using dynamic contrast-enhanced MRI and immunohistochemical markers.

IntroductionThe purpose of the present study was to look for the possible predictors which might discriminate between high- and low-grade gliomas by pooling dynamic contrast-enhanced (DCE)-perfusion derived indices and immunohistochemical markers.MethodsDCE-MRI was performed in 76 patients with different grades of gliomas. Perfusion indices, i.e., relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), permeability (ktrans and kep), and leakage (ve) were quantified. MMP-9-, PRL-3-, HIF-1α-, and VEGF-expressing cells were quantified from the excised tumor tissues. Discriminant function analysis using these markers was used to identify discriminatory variables using a stepwise procedure. To look for correlations between immunohistochemical parameters and DCE metrics, Pearsons correlation coefficient was also used.ResultsA discriminant function for differentiating between high- and low-grade tumors was constructed using DCE-MRI-derived rCBV, kep, and ve. The form of the functions estimated are “D1 = 0.642 × rCBV + 0.591 × kep − 1.501 × ve − 1.550” and “D2 = 1.608 × rCBV + 3.033 × kep + 5.508 × ve − 8.784” for low- and high-grade tumors, respectively. This function classified overall 92.1% of the cases correctly (89.1% high-grade tumors and 100% low-grade tumors). In addition, VEGF expression correlated with rCBV and rCBF, whereas MMP-9 expression correlated with kep. A significant positive correlation of HIF-1α with rCBV and VEGF expression was also found.ConclusionDCE-MRI may be used to differentiate between high-grade and low-grade brain tumors non-invasively, which may be helpful in appropriate treatment planning and management of these patients. The correlation of its indices with immunohistochemical markers suggests that this imaging technique is useful in tissue characterization of gliomas.

Inhibition of N-(4-hydroxyphenyl)retinamide-induced autophagy at a lower dose enhances cell death in malignant glioma cells

The question whether chemotherapy-induced autophagy is causative to the demise of the cells or a part of the survival mechanism activated during cellular distress is unclear. Others and we have previously demonstrated apoptosis-inducing capacity of N-(4-hydroxyphenyl)retinamide (4-HPR) in malignant glioma cells. We provide evidences of 4-HPR-induced autophagy at a lower concentration (5 microM). Suboptimal dose of 4-HPR treatment of malignant glioma cell lines increased G(2)/M arrest, whereas cell accumulated in S phase at a higher concentration. 4-HPR-induced autophagy was associated with acidic vacuole [acidic vesicular organelle (AVO)] formation and recruitment of microtubule-associated protein light chain 3 (LC3). At a higher concentration of 10 microM of 4-HPR, glioma cells undergoing apoptosis manifested autophagic features indicated by autophagosome formation, AVO development and LC3 localization. Autophagy inhibition at an early stage by 3-methyl adenine inhibited the AVO formation and LC3 localization with an enhancement in cell death. Bafilomycin A1, a specific inhibitor of vacuolar type Hthorn-ATPase also prevented AVO formation without effecting LC-3 localization pattern and also enhanced the extent of 4-HPR-induced cell death. 4-HPR activated c-jun and P38(MAPK) at both 5 and 10 microM concentrations, whereas increased activation of extracellular signal-regulated kinase 1/2 and NF-kappaB was seen only at lower dose. Inhibiting phosphoinositide 3-kinase and mitogen-activated protein kinases pathways modulated 4-HPR-induced cell death. This is the first report that provides evidences that besides apoptosis induction 4-HPR can also induce autophagy. These results indicate that 4-HPR-induced autophagy in glioma cell may provide survival advantage and inhibition of autophagy may enhance the cytotoxicity to 4-HPR.

Differentiation of infective from neoplastic brain lesions by dynamic contrast-enhanced MRI

IntroductionIt is not always possible to differentiate infective from neoplastic brain lesions with conventional MR imaging. In this study, we assessed the utility of various perfusion indices in the differentiation of infective from neoplastic brain lesions.Methods A total of 103 patients with infective brain lesions (group I, n=26) and neoplastic brain lesions (high-grade glioma, HGG, group II, n=52; low-grade glioma, LGG, group III, n=25) underwent dynamic contrast-enhanced MR imaging. The perfusion indices, including relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), transfer coefficient (ktrans) and leakage (ve), were calculated and their degree of correlation with immunohistologically obtained microvessel density (MVD) and vascular endothelial growth factor (VEGF) determined. The rCBV was corrected for the leakage effect. Discriminant analysis for rCBV, rCBF, ktrans and ve was performed to predict the group membership of each case and post hoc analysis was performed to look for group differences.ResultsThe rCBV, rCBF, ktrans, ve, MVD and VEGF were significantly different (P<0.001) between the three groups. Discriminant analysis showed that rCBV predicted 73.1% of the infective lesions, 84.6% of the HGG and 72.0% of the LGG. The rCBF classified 86.5% of the HGG, 80.0% of the LGG and 65.4% of the infective lesions. The ktrans discriminated 98.1% of the HGG, 76.0% of the LGG and 88.5% of the infective lesions correctly. The ve classified 98.1% of the HGG, 76.0% of the LGG and 84.6% the infective lesions. The rCBV was correlated significantly with MVD and VEGF, while the correlation between ktrans and MVD was not significant.ConclusionPhysiological perfusion indices such as ktrans and ve appear to be useful in differentiating infective from neoplastic brain lesions. Adding these indices to the current imaging protocol is likely to improve tissue characterization of these focal brain mass lesions.

Intracranial aneurysms in patients 18 years of age or under, are they different from aneurysms in adult population?

SummaryBackground. Intracranial aneurysms are extremely uncommon in the first two decades of life. This study was undertaken to assess the clinicoradiological features and surgical outcome of intracranial aneurysms in patients less than or equal to 18 years of age; and, to highlight the differences between these and intracranial aneurysms seen in adult patients.Methods and material. Twenty-two patients, 18 years of age or under (male:female ratio=1.75:1; mean age 14.18±3.8 years, age range 5 to 18 years) and 451 adult patients aged older than 18 years (male:female ratio=1:1.05; mean age 48.21±12.71 years, age range, 19 to 81 years) were treated for intracranial aneurysms at our center between January 1991 and July 2003. The univariate statistical analysis was used to compare differences between the two groups.Findings. The patients under 18 years constituted 4.6% of the total patient population having intracranial aneurysms. The incidence of associated medical diseases was greater in patients under 18 years than in the adults (9% versus 0.26%, p<0.05). The incidence of seizures was more than double in patients under 18 years (36% versus 17%, p<0.05). The incidence of intracerebral haematoma (ICH; 41% versus 22.5%, p>0.05), intraventricular haemorrhage (IVH; 45% versus 34%, p>0.05), and hydrocephalus (36% versus 25%, p>0.05) were higher in patients under 18 years. In adult patients, anterior communicating artery (AcoA) and in children, ICA bifurcation were the most frequent sites of aneurysm formation respectively (p<0.05). The incidence of giant aneurysms was nearly double in children (13.6% versus 6.5%, p>0.05). The incidence of clinical vasospasm was almost the same in both groups. The overall outcome was favourable in 82% of patients under 18 years and 58.8% in adults. The management mortality in patients under 18 years was 9.1%, while in the adult patients, it was 19%.Conclusion. In patients under 18 years of age, there was a definite male predominance; a higher incidence of seizures; and, the ICA bifurcation formed the most frequent site of intracranial aneurysms. In adults, AcoA a was the commonest site. Rebleeding and delayed ischaemic deficits were the major causes of morbidity. Favorable outcome after surgery in young patients was better in comparison to their adult counterparts.

Effect of spinal cord signal intensity changes on clinical outcome after surgery for cervical spondylotic myelopathy

OBJECT The presence of intramedullary T2 high signal intensity changes in patients with cervical spondylotic myelopathy (CSM) indicates the existence of a chronic spinal cord compressive lesion. However, the prognostic significance of signal intensity changes remains controversial. The purpose of this study was to evaluate the effect of spinal cord T2 signal intensity changes on the outcome after surgery for CSM. METHOD In a prospective study, 64 patients with CSM who underwent surgical treatment between October 2006 and April 2008 using an anterior approach were included. Based on the clinical symptoms and signs present, the severity of neurological deficits of all patients was scored according to a modified Japanese Orthopaedic Association scale score for CSM just before the surgery and at 6 months follow-up. Recovery rates were calculated at 6 months. RESULTS There were 22 patients who did not have spinal cord intensity changes on MR imaging and 44 who demonstrated high-intensity signal changes on T2-weighted images (focal or segmental). No statistically significant differences were found in recovery rates between cases with T2 signal intensity changes and those with no signal intensity changes. However, the postoperative modified Japanese Orthopaedic Association scale scores and the recovery rates were much lower in patients with multisegmental signal intensity changes compared with those without these changes or those with focal signal intensity change, and ANOVA demonstrated this difference to be statistically significant (p < 0.05). CONCLUSION Multisegmental spinal cord signal intensity changes on T2-weighted MR imaging are predictors of a poor outcome in terms of functional recovery rate in patients undergoing operations for CSM.

Intrinsic third ventricular craniopharyngiomas: report on six cases and a review of the literature

BACKGROUND Craniopharyngiomas constitute 2 to 4% of intracranial neoplasms. However, the purely intraventricular variety are rare. Their magnetic resonance imaging (MRI) characteristically shows an intact third ventricular floor, a patent suprasellar cistern, an intact pituitary stalk, and the absence of sellar abnormalities. METHODS Between 1994 and June 2002, 6 patients with purely intraventricular craniopharyngioma were surgically managed. There were 4 cystic and 2 solid lesions. The surgical approaches utilized included a frontal, parasagittal, transcallosal approach with the third ventricle being accessed using either the transforaminal or subchoroidal approach (n = 3); pterional, transsylvian (n = 1), and bifrontal interhemispheric (n = 2) approaches in which the third ventricle was accessed via the lamina terminalis. A ventriculoperitoneal shunt was required for one of the 3 patients with hydrocephalus. RESULTS Total excision was performed in 3 patients with cystic craniopharyngioma, while a small residual lesion was left adherent to the third ventricular floor in the others. There was one perioperative mortality because of septicemia. Two patients required thyroxine supplementation. Two patients developed transient and one other patient a sustained diabetes insipidus. The 2 patients with solid tumors received radiotherapy for the residual lesions. At follow up ranging from 8 to 36 months, neither tumor recurrence nor regrowth was observed in any of the patients. The symptoms of raised intracranial pressure, hypothalamic dysfunction or visual field defects had resolved. CONCLUSIONS Intraventricular craniopharyngiomas occur in an older population and present mainly with raised intracranial pressure. Visual and endocrinologic imbalances are much less in these lesions compared to the suprasellar craniopharyngiomas. They mainly attach to the third ventricular floor. The surgical approaches to the third ventricle, along with radiotherapy and hormone supplementation, were successful in the management of these rare tumors.

Thoracic myelopathy secondary to ossified ligamentum flavum.

Summary.Summary.Background: Focal ossification of the ligamentum flavum (OLF) forms one of the rare causes of thoracic myelopathy. The lower thoracic spine is most frequently affected and the patients present with initial posterior column disturbances followed by progressively increasing spastic paraparesis. The pathogenesis of OLF has not been conclusively established.Method: Five patients with thoracic myelopathy due to OLF underwent decompressive laminectomy and excision of the ligamentum flavum. Their MRI delineated a linear or beak like excrescence, uniformly hypo-intense on T1 and T2 weighted images, situated posterior to the thecal sac. A comparison between the pre-operative neurological status and the status at follow-up was done using Harshs myelopathic grading.Finding: Decompressive laminectomy followed by the drilling of the OLF and its excision, occasionally along with the adherent outer layer of the dura, resulted in significant improvement in motor weakness and tingling sensations. However, at the last available follow-up, none of the patients had retained their ability to run briskly (grade I) and all of them had residual spasticity.Interpretation: OLF may significantly contribute to a spatial reduction of the thoracic spinal canal resulting in paraparesis. The T2 weighted sagittal image of the magnetic resonance imaging (MRI) is the modality of choice for screening of the longitudinal extent of the OLF. A rapid neurological improvement occurs following decompressive laminectomy and excision of the OLF. However, the persistence of residual spasticity at follow-up may be due to irreversible changes within the cord by the significant thecal compression and the delay between the onset of initial symptoms and signs and surgical decompression.