Perfusion magnetic resonance imaging in differentiation of neurocysticercosis and tuberculoma

Contribution of advanced neuro-imaging (MR diffusion, perfusion and proton spectroscopy) in differentiation between low grade gliomas GII and MR morphologically similar non neoplastic lesions

Background

Non-neoplastic brain lesions can be misdiagnosed as low-grade gliomas. Conventional magnetic resonance (MR) imaging may be non-specific. Additional imaging modalities such as spectroscopy (MRS), perfusion and diffusion imaging aid in diagnosis of such lesions. However, contradictory and overlapping results are still present. Hence, our purpose was to evaluate the role of advanced neuro-imaging in differentiation between low-grade gliomas (WHO grade II) and MR morphologically similar non-neoplastic lesions and to prove which modality has the most accurate results in differentiation.

Results

All patients were classified into two main groups: patients with low-grade glioma (n = 12; mean age, 38.8 ± 16; 8 males) and patients with non-neoplastic lesions (n = 27; mean age, 36.6 ± 15; 19 males) based on the histopathological and clinical–radiological diagnosis. Using ROC curve analysis, a threshold value of 0.93 for rCBV (AUC = 0.875, PPV = 92%, NPV = 71.4%) and a threshold value of 2.5 for Cho/NAA (AUC = 0.829, PPV = 92%, NPV = 71.4%) had 85.2% sensitivity and 83.3% specificity for predicting neoplastic lesions. The area under the curve (AUC) of ROC analysis was good for relative cerebral blood volume (rCBV) and Cho/NAA ratios (> 0.80) and fair for Cho/Cr and NAA/Cr ratios (0.70–0.80). When the rCBV measurements were combined with MRS ratios, significant improvement was observed in the area under the curve (AUC) (0.969) with improved diagnostic accuracy (89.7%) and sensitivity (88.9%).

Conclusions

Evaluation of rCBV and metabolite ratios at MRS, particularly Cho/NAA ratio, may be helpful in differentiating low-grade gliomas from non-neoplastic lesions. The combination of dynamic susceptibility contrast (DSC) perfusion and MRS can significantly improve the diagnostic accuracy and can help avoiding the need for an invasive biopsy.

Advanced magnetic resonance imaging and spectroscopy in a case of neurocysticercosis from North America

Neurocysticercosis (NCC) is a parasitic infection caused by Cysticercus cellulosae, the metacestode of pork tapeworm (Taenia solium). NCC is one of the most common public health problems worldwide. We present a patient harboring a bilobed ring-enhancing lesion with a presumed diagnosis of brain metastasis, who returned to the USA after traveling to an endemic region. The diagnosis of NCC was established based on a characteristic resonance of succinate on proton magnetic resonance spectroscopy. Also, higher mean diffusivity and lower fractional anisotropy along with relative cerebral blood volume were observed from the lesion compared to contralateral normal brain regions. Multiparametric analysis may improve the differential diagnosis of ring-enhancing intracranial lesions such as NCC.

Monocyte Gene Expression Distinguishes Enhancing Brain Parenchymal Cysticercal Granulomas From Tuberculomas

BACKGROUND

In patients with enhancing brain parenchymal lesions, parenchymal neurocysticercosis (pNCC) is often difficult to distinguish from tuberculoma, necessitating biopsy or empirical therapy.

METHODS

In a prospective study, peripheral blood monocytes were isolated from patients with definitive pNCC (n = 39) and brain tuberculomas (n = 20). Patients with tuberculomas were diagnosed by the presence of concurrent systemic tuberculosis (n = 7), pathological or bacteriological confirmation (n = 5), and resolution of typical brain lesions following a therapeutic trial of antituberculous therapy (n = 8). Expressions of 14 NCC-associated monocyte genes were determined by quantitative polymerase chain reaction and analyzed for diagnostic usefulness between the 2 groups.

RESULTS

Expression of 7 genes (TAX1BP1, RAP1A, PLCG2, TOR3A, GBP1P1, LRRFIP2, and FEZ2) was significantly higher in pNCC patients than in tuberculoma patients, with TAX1BP1 and RAP1A expressions more than 22- and 5-fold higher in pNCC patients. TAX1BP1 had the highest sensitivity of 66.7% at a specificity of 100% in discriminating pNCC from tuberculoma. A combination of TAX1BP1 and RAP1A increased the sensitivity to 84.6%, and including GBP1P1 with TAX1BP1 and RAP1A further increased sensitivity to 87.2% while maintaining specificity of 100%.

CONCLUSIONS

Expression of a panel of genes in blood monocytes distinguishes pNCC from brain tuberculomas in patients with enhancing brain lesions.

Neurologic Complications of Tuberculosis

PURPOSE OF REVIEW

This article describes the current epidemiology, common clinical characteristics, and up-to-date evidence-based approaches to the diagnosis and management of the most common neurologic complications of tuberculosis (TB): tuberculous meningitis, intracranial tuberculoma, and spinal TB.

RECENT FINDINGS

Central nervous system (CNS) TB remains common and associated with significant mortality and neurologic sequelae worldwide. Human immunodeficiency virus (HIV) co-infection is strongly associated with both the development of and mortality due to CNS TB. Strongyloides co-infection is associated with reduced CNS inflammation and improved outcomes in the setting of tuberculous meningitis. Stroke remains a common complication of tuberculous meningitis, and emerging evidence suggests aspirin may be used in this context. Although a recent nucleic acid amplification test has demonstrated suboptimal sensitivity in the diagnosis of CNS TB, emerging diagnostic techniques include cell-free DNA, peripheral blood microRNA, metagenomic next-generation sequencing, and advanced imaging techniques, but these are not yet well validated. CNS TB is associated with high mortality even with current treatment regimens, although novel, promising strategies for treatment are under investigation, including a combination of IV isoniazid and ethambutol and high-dose rifampicin.

SUMMARY

TB can affect the nervous system in various ways and is associated with high mortality. Diagnosis remains challenging in endemic settings, with empiric treatment often initiated without a definitive diagnosis. Furthermore, optimal treatment regimens remain uncertain because current treatment for all forms of CNS TB is extrapolated from trials of tuberculous meningitis whereas the role of steroids in people with HIV and tuberculous meningitis remains controversial.

Giant tuberculoma of the corpus callosum, the unforeseen diagnosis

OBJECTIVE

Isolated intracranial tuberculomas are rare, especially in adults and it is not uncommon that they are easily confused with other diseases. To address this issue, we reported a case of a tuberculoma of the corpus callosum focusing on clinical characteristics, diagnostic clues, and outcome.

CONCLUSIONS

Intracranial masses are frequently targeted as neoplastic pathology with surgical treatment in most cases. It is important to distinguish between neuro tuberculoma and brain tumors because of their different management and prognosis. Therefore even in absence of a known history of primary TB and in immunocompetent patients, tuberculoma must be in the differential diagnosis of solitary intracranial lesions also in countries where TB is not endemic.

Assessment of Blood-Brain Barrier Integrity in Tuberculous Meningitis Using Dynamic Contrast-Enhanced MR Perfusion

Objective Tuberculous meningitis (TBM) is the most common form of central nervous system tuberculosis. The aim of the study was to quantitatively evaluate blood-brain barrier (BBB) perfusion changes in TBM patients using dynamic contrast-enhanced (DCE) MR perfusion. Methods and Material Thirty untreated patients of TBM and 10 healthy controls were prospectively evaluated by conventional imaging and DCE MR perfusion. Mean permeability indices- K trans and Ve-were calculated from multiple regions of interest (ROIs) placed in basal cisterns and comparison was done between the patients and controls. Results The permeability indices were significantly higher (where p < 0.001) in cisterns of TBM patients who showed basal meningeal enhancement when compared with healthy controls. Significant differences in permeability were observed between "enhancing" cases and controls as well as in "enhancing" cases when compared with the "non-enhancing" cases. However, no significant difference was observed in the mean cisternal value between "non-enhancing" cases and the controls. K trans with a cutoff value of > 0.0838 had 81.6% sensitivity and 78.6% specificity in differentiating cases and controls while V e mean value with a cutoff value of 0.0703 showed 86.8% sensitivity and 91.4% specificity in predicting the permeability difference between the cases and controls. Conclusion DCE MR perfusion is useful in the quantitative measurement of disruption of BBB and perfusion alterations in patients of TBM.

Neurotuberculosis: an update

Tuberculous (TB) meningitis (TBM), accounting for 70-80% of cases of neurotuberculosis, is one of the most severe forms of extrapulmonary tuberculosis. Two-thirds of new TB cases come from eight countries. Polymorphisms in toll-interleukin-1 receptor domain and in leukotriene A4 hydrolase (LTA4H) gene, affect the risk of inflammation in TBM. The common site of tuberculoma in children is cerebellum, and they may rarely develop tuberculous encephalopathy which has a high mortality. Young females with a high cerebrospinal fluid (CSF) protein have an increased predisposition to develop optochiasmatic arachnoiditis. Spinal TB meningitis may mimic transverse myelitis or Guillain-Barre syndrome. An extra-neural focus of TB should be sought clinically and radiologically as it may indicate safer and more accessible sites for diagnostic samplings. Cartridge-based nucleic acid amplification test (CBNAAT), also known as Genexpert test, is a polymerase chain reaction (PCR)-based method for detection of TB which also detects rifampicin resistance as it targets the rpob gene of mycobacteria. Line probe assays, based on PCR and reverse hybridization methods, identify mutations associated with drug resistance within a week. TBM being a paucibacillary disease, often evades a definite diagnosis and empirical treatment for a minimum of 9 months is warranted based on clinical judgement. All TBM patients should receive adjunctive corticosteroids, even those with HIV infection. Drug resistance is strongly associated with previous treatment and bedaquiline as well as delamanid have received approvals for multidrug resistant (MDR) TB. The key principle of managing MDR TB is never to add a single drug to a failing regimen. Correct combination and duration of most effective second line drugs in MDR TB require further modifications. Early shunting should be considered in those with hydrocephalus failing medical management. The single most important determinant of outcome is the stage of TBM at which treatment has been started.

Taenia solium Cysticercosis and Its Impact in Neurological Disease

Taenia solium neurocysticercosis (NCC) is endemic in most of the world and contributes significantly to the burden of epilepsy and other neurological morbidity. Also present in developed countries because of immigration and travel, NCC is one of few diseases targeted for eradication. This paper reviews all aspects of its life cycle (taeniasis, porcine cysticercosis, human cysticercosis), with a focus on recent advances in its diagnosis, management, and control. Diagnosis of taeniasis is limited by poor availability of immunological or molecular assays. Diagnosis of NCC rests on neuroimaging findings, supported by serological assays. The treatment of NCC should be approached in the context of the particular type of infection (intra- or extraparenchymal; number, location, and stage of lesions) and has evolved toward combined symptomatic and antiparasitic management, with particular attention to modulating inflammation. Research on NCC and particularly the use of recently available genome data and animal models of infection should help to elucidate mechanisms of brain inflammation, damage, and epileptogenesis.

CNS Infections in Immunoincompetent Patients : Neuroradiological and Clinical Features

In patients with immunodeficiency the pathogen spectrum of central nervous system (CNS) infections is broader and different from that of immunocompetent patients. Numerous opportunistic infections are characterized by a high prevalence of viral, bacterial and parasitic pathogens, and depend on the type of impaired immune defense, for example impaired T‑cell or monocyte function, monoclonal antibody treatment, and impaired granulocyte function. Neuroradiological features as well as laboratory findings are often different and versatile in comparison to immunocompetent individuals and pathognomonic imaging findings do not exist; however, knowledge of possible pathways of pathogens in the CNS and preferred tissue affection may help in narrowing down differential diagnoses. Therefore, knowledge of the type of patient and the performed immunomodulatory therapy is essential for the neuroradiological assessment and the differential diagnostic considerations. Moreover, parenchymal reactions in the sense of an immune reconstitution inflammatory syndrome (IRIS) can occur when immunocompetence is restored. This review focus on the most common pathologies in immunocompromised patients, and an overview of imaging features but also of pathology and clinical aspects is given. The synopsis of anamnestic information, clinical findings and structured analysis of the lesion pattern, its spread and short-term follow-up may increase the correct diagnostic classification; however, the gold standard is still determination of the pathogen in the cerebrospinal fluid (CSF), blood cultures or biopsies.