Contrast-enhanced flair imaging in the evaluation of infectious leptomeningeal diseases

Imaging of brain barrier inflammation and brain fluid drainage in human neurological diseases

The intricate relationship between the central nervous system (CNS) and the immune system plays a crucial role in the pathogenesis of various neurological diseases. Understanding the interactions among the immunopathological processes at the brain borders is essential for advancing our knowledge of disease mechanisms and developing novel diagnostic and therapeutic approaches. In this review, we explore the emerging role of neuroimaging in providing valuable insights into brain barrier inflammation and brain fluid drainage in human neurological diseases. Neuroimaging techniques have enabled us not only to visualize and assess brain structures, but also to study the dynamics of the CNS in health and disease in vivo. By analyzing imaging findings, we can gain a deeper understanding of the immunopathology observed at the brain-immune interface barriers, which serve as critical gatekeepers that regulate immune cell trafficking, cytokine release, and clearance of waste products from the brain. This review explores the integration of neuroimaging data with immunopathological findings, providing valuable insights into brain barrier integrity and immune responses in neurological diseases. Such integration may lead to the development of novel diagnostic markers and targeted therapeutic approaches that can benefit patients with neurological disorders.

Review of standard paediatric neuroradiology MRI protocols from 12 UK tertiary paediatric hospitals: is there much variation between centres?

AIM

To investigate how magnetic resonance imaging (MRI) examinations are protocolled in tertiary paediatric neuroradiology centres around the UK for some of the more common presentations encountered in paediatric neuroradiology, and to identify any variations of note.

MATERIALS AND METHODS

All 19 UK tertiary paediatric neuroradiology centres registered with the British Society of Neuroradiologists-Paediatric Group were contacted and asked if they could provide a copy of their standard MRI protocols. Twelve responded (63%) and 10 of the more common presentations were selected and the standard acquired sequences obtained at each participating centre were compared. Where available the collated protocols were also compared against current published guidance.

RESULTS

The basic sequences carried out by centres around the UK are similar; however, there are lots of variations overall. The only standardised protocol currently being implemented nationally in paediatric imaging is that for brain tumours. Otherwise, chosen protocols are generally dependent on the preferences and technical capabilities of individual centres. Suggested published protocols also exist for non-accidental injury (NAI), multiple sclerosis, epilepsy, and head and neck imaging.

CONCLUSIONS

The differences in MRI protocolling depend in part on technical capabilities and in part on the experience and preferences of the paediatric neuroradiologists at each centre. For most presentations, there is no consensus as to what constitutes the perfect protocol. The present results will be useful for specialist centres who may wish to review their current protocols, and for more generalist centres to use as a reference to guide their MRI protocolling.

Comparison of post contrast fluid attenuated inversion recovery, 3D T1-SPACE, and T1W MRI sequences with fat suppression in the diagnosis of infectious meningitis

OBJECTIVE

To assess the usefulness of post contrast Fluid attenuated inversion recovery (FLAIR), 3D T1-SPACE, and T1W magnetic resonance imaging (MRI) sequences with fat suppression in diagnosis of infectious meningitis.

METHODS

75 patients with clinical suspicion of meningitis were evaluated with post contrast FLAIR (PC-FLAIR), post contrast T1-SPACE (PC-T1-SPACE), and post contrast T1WI (PC-T1WI). Sensitivity, specificity, positive predictive value, and negative predictive value of individual sequences were assessed.

RESULTS

The sensitivity of PC-FLAIR (88.4%) was greater than PC-T1-SPACE (85.5%) and PC-T1WI (82.6%), considering cerebrospinal fluid (CSF) analysis as gold standard (p < 0.05). Kappa inter-rater agreement between two radiologists was 0.921 for PC-T1-SPACE, 0.921 for PC-T1WI, and 1.0 for PC-FLAIR with a p value <0.05. Both PC-T1-SPACE and PC-FLAIR performed equally in sulcal space enhancement. PC-T1-SPACE and PC-T1WI performed better in evaluation of pachymeningeal enhancement, ependymal enhancement in cases of ventriculitis, whereas PC-FLAIR was more sensitive in assessment of basal cistern enhancement and enhancement along the cerebellar folia.

CONCLUSION

Meningeal enhancement could be better appreciated in PC-FLAIR image than PC-T1WI and PC-T1-SPACE. Enhancement in PC-T1-SPACE was comparable to that of PC-T1WI. Being a T1 based spin echo sequence, PC-T1-SPACE has all the advantages of PC-T1WI in addition to its ability to differentiate meningeal enhancement from leptomeningeal vessels. Hence, PC-T1WI can be replaced by PC-T1-SPACE and PC-FLAIR can be added to routine MRI protocol in suspected case of meningitis.

The value of contrast-enhanced FLAIR magnetic resonance imaging in detecting meningeal abnormalities in suspected cases of meningitis compared to conventional contrast-enhanced T1WI sequences

Background

Early diagnosis of meningitis with magnetic resonance imaging (MRI) would be useful for appropriate and effective management, decrease morbidity and mortality, and provide better diagnosis and treatment. The objective of the current study is to compare the accuracy of contrast-enhanced FLAIR (CE-FLAIR) and contrast-enhanced T1WI (CE-T1WI) in the detection of meningeal abnormalities in suspected cases of meningitis.

Results

Out of 45 patients, 37 patients were confirmed to have meningitis on CSF analysis. Out of the 37 patients, 34 patients were positive on CE-FLAIR sequence and 27 were positive on CE-T1WI. The sensitivity of CE-FLAIR sequence was 91.9% and specificity 100%, while the sensitivity of CE-T1WI sequence was 73% and specificity 100%.

Conclusion

CE-FLAIR is more sensitive than CE-T1WI in diagnosis of meningitis. It is recommended to be used in any cases with clinically suspected meningitis.

Postcontrast Fluid-Attenuated Inversion Recovery (FLAIR) Sequence MR Imaging in Detecting Intracranial Pathology

Background

Imaging sequences for detection of meningeal and parenchymal lesions are critical in intracranial pathology. Our study analysed FLAIR MRI sequence for evaluating postcontrast enhancement.

Objectives

FLAIR imaging sequences have been used in evaluation of enhancement in the brain. We conducted a study of FLAIR imaging sequences to better delineate postcontrast enhancement.

Materials and Methods

In this prospective hospital-based observational study, postcontrast T1 MTC and delayed postcontrast T2 FLAIR and T1 FLAIR images of 66 patients with intracranial pathology were assessed by experienced radiologists from November 2017 to November 2019.

Results

28 cases of meningeal enhancement were identified in delayed postcontrast T2 FLAIR images. Low-grade gliomas included in the study showed postcontrast enhancement on postcontrast T1 MTC images. Multiple sclerosis lesions were better seen on postcontrast T1 FLAIR. In extraaxial lesions of 11 cases of meningioma, brighter enhancement was seen on delayed postcontrast T2 FLAIR images.

Conclusion

We found that delayed postcontrast T2 FLAIR was better in detection of meningeal enhancement in infectious meningitis and in meningitis carcinomatosis than T1 MTC images. In delayed postcontrast T2 FLAIR images, intra-axial parenchyma lesions appeared more conspicuous or similar to T1 MTC images. Delayed postcontrast T1 FLAIR images provided better anatomic delineation of intra-axial lesions.

Detection of Coalescent Acute Mastoiditis on MRI in Comparison with CT

Purpose

Current imaging standard for acute mastoiditis (AM) is contrast-enhanced computed tomography (CT), revealing inflammation-induced bone destruction, whereas magnetic resonance imaging (MRI) outperforms CT in detecting intracranial infection. Our aim was to compare the diagnostic performance of MRI with CT in detecting coalescent AM and see to which extent MRI alone would suffice to diagnose or rule out this condition.

Methods

The MR images of 32 patients with AM were retrospectively analyzed. Bone destruction was evaluated from T2 turbo spin echo (TSE) and T1 Gd magnetization-prepared rapid acquisition with gradient echo (MPRAGE) images. Intramastoid enhancement and diffusion restriction were evaluated subjectively and intramastoid apparent diffusion coefficient (ADC) values were measured. The MRI findings were compared with contrast-enhanced CT findings of the same patients within 48 h of the MR scan.

Results

Depending on the anatomical subsite, MRI detected definite bone defects with a sensitivity of 100% and a specificity of 54–82%. Exception was the inner cortical table where sensitivity was only 14% and specificity was 76%. Sensitivity for general coalescent mastoiditis remained 100% due to multiple coexisting lesions. The absence of intense enhancement and non-restricted diffusion had a high negative predictive value for coalescent mastoiditis: an intramastoid ADC above 1.2 × 10⁻³ mm²/s excluded coalescent mastoiditis with a negative predictive value of 92%.

Conclusion

The MRI did not miss coalescent mastoiditis but was inferior to CT in direct estimation of bone defects. When enhancement and diffusion characteristics are also considered, MRI enables dividing patients into low, intermediate and high-risk categories with respect to coalescent mastoiditis, where only the intermediate risk group is likely to benefit from additional CT.

Standardized approaches for clinical sampling and endpoint ascertainment in tuberculous meningitis studies

Tuberculous meningitis (TBM), the most severe manifestation of tuberculosis, has poorly understood immunopathology and high mortality and morbidity despite antituberculous therapy. This calls for accelerated clinical and basic science research in this field. As TBM disproportionally affects poorer communities, studies are often performed in resource-limited environments, creating challenges for data collection and harmonisation. Comparison of TBM studies has been hampered by variation in sampling strategies, study design and choice of study endpoints.  Based on literature review and expert consensus, this paper provides firstly, practical recommendations to enable thorough diagnostic, pathophysiological and pharmacokinetic studies using clinical samples, and facilitates better data aggregation and comparisons across populations and settings. Secondly, we discuss clinically relevant study endpoints, including neuroimaging, functional outcome, and cause of death, with suggestions of how these could be applied in different designs for future TBM studies.

Standardized approaches for clinical sampling and endpoint ascertainment in tuberculous meningitis studies

Tuberculous meningitis (TBM), the most severe manifestation of tuberculosis, has poorly understood immunopathology and high mortality and morbidity despite antituberculous therapy. This calls for accelerated clinical and basic science research in this field. As TBM disproportionally affects poorer communities, studies are often performed in resource-limited environments, creating challenges for data collection and harmonisation. Comparison of TBM studies has been hampered by variation in sampling strategies, study design and choice of study endpoints.  Based on literature review and expert consensus, this paper provides firstly, practical recommendations to enable thorough diagnostic, pathophysiological and pharmacokinetic studies using clinical samples, and facilitates better data aggregation and comparisons across populations and settings. Secondly, we discuss clinically relevant study endpoints, including neuroimaging, functional outcome, and cause of death, with suggestions of how these could be applied in different designs for future TBM studies.

Amide Proton Transfer-Weighted (APTw) Imaging of Intracranial Infection in Children: Initial Experience and Comparison with Gadolinium-Enhanced T1-Weighted Imaging

Purpose

To evaluate the performance of amide proton transfer-weighted (APTw) imaging against the reference standard of gadolinium-enhanced T1-weighted imaging (Gd-T1w) in children with intracranial infection.

Materials and Methods

Twenty-eight pediatric patients (15 males and 13 females; age range 1-163 months) with intracranial infection were recruited in this study. 2D APTw imaging and conventional MR sequences were conducted using a 3 T MRI scanner. Kappa (κ) statistics and the McNemar test were performed to determine whether the hyperintensity on APTw was related to the enhancement on Gd-T1w. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of APTw imaging to predict lesion enhancement were calculated.

Result

In twelve patients with brain abscesses, the enhancing rim of the abscesses on the Gd-T1w images was consistently hyperintense on the APTw images. In eight patients with viral encephalitis, three showed slight spotted gadolinium enhancement, while the APTw image also showed a slight spotted high signal. Five of these patients showed no enhancement on Gd-T1w and isointensity on the APTw image. In eleven patients with meningitis, increased APTw signal intensities were clearly visible in gadolinium-enhancing meninges. Sixty infectious lesions (71%) showed enhancement on Gd-T1w images. The sensitivity and specificity of APTw were 93.3% (56/60) and 91.7% (22/24). APTw demonstrated excellent agreement (κ = 0.83) with Gd-T1w, with no significant difference (P = 0.69) in detection of infectious lesions.

Conclusions

These initial data show that APTw MRI is a noninvasive technique for the detection and characterization of intracranial infectious lesions. APTw MRI enabled similar detection of infectious lesions to Gd-T1w and may provide an injection-free means of evaluation of intracranial infection.

Neonatal Neuroimaging

Significant advances in the field of neonatal imaging has resulted in the generation of large complex data sets of relevant information for routine daily clinical practice, and basic and translational research. The evaluation of this data is a complex task for the neonatal imager who must distinguish normal and incidental findings from clinically significant abnormalities which are often adjunctive data points applicable to clinical evaluation and treatment. This review provides an overview of the imaging manifestations of disease processes commonly encountered in the neonatal brain. Since MRI is currently the highest yield technique for the diagnosis and characterization of the normal and abnormal brain, it is therefore the focus of the majority of this review. When applicable, discussion of some of the pertinent known pathophysiology and neuropathological aspects of disease processes are reviewed.

Central Nervous System involvement in tuberculosis: An MRI study considering differences between patients with and without Human Immunodeficiency Virus 1 infection

BACKGROUND

Magnetic resonance imaging (MRI) is largely used in the diagnosis of central nervous system involvement of tuberculosis (CNSTB), yet there is no MRI comparison study between HIV+ and HIV- patients with CNSTB. The aim of the present study was to identify MRI differences in CNSTB between HIV+ and HIV- patients and possibly find early characteristics that could raise the suspect of this disease.

METHODS

We included all patients admitted in our institution between 2011 and 2018 with confirmed diagnosis of CNSTB, and MRI performed in the first week. Patients with preexisting brain pathology or immunodeficiency not HIV related were excluded. We compared CNSTB MRI features between the two groups.

RESULTS

Sixty-nine patients were included (19 HIV+; 50 HIV-). Findings in HIV+ group: 6 lung TB, 5 hydrocephalus, 4 meningeal enhancement, 6 stroke, 2 hemorrhages, and 10 tuberculomas. HIV- group: 22 lung tuberculosis, 15 hydrocephalus, 21 meningeal enhancement, 5 stroke, 4 hemorrhages, 20 tuberculomas. The only statistically significant difference between the two groups was in the stroke occurrence, more frequent in the HIV+ group (P=.028), all involving the basal ganglia.

CONCLUSIONS

Stroke involving the basal ganglia best differentiates CNSTB patients who are HIV+ from those HIV-. This finding was not correlated with meningeal enhancement suggesting that small arteries involvement might precede it. Therefore, we think that HIV+ patients with a new onset of stroke should be evaluated for CNSTB. Follow-up MRI should also be planned since meningeal enhancement might appear in later stages of the disease.

Meningeal enhancement depicted by magnetic resonance imaging in tumor patients: neoplastic meningitis or therapy-related enhancement?

PURPOSE

To assess the prevalence of false-positive meningeal contrast enhancement in patients with solid tumors who were undergoing chemotherapy.

METHODS

A total of 2572 magnetic resonance imaging (MRI) examinations of the brain were retrospectively evaluated by two readers for the presence of pathological meningeal contrast enhancement conspicuous for neoplastic meningitis. These patients either had malignant melanoma, breast or lung cancer, or lymphoma. The reference standards were cerebrospinal fluid cytology results and follow-up MRI. In cases with pathological contrast enhancement that decreased upon follow-up and non-malignant cytology, the enhancement pattern was further described as pial or dural, local or diffuse, or supra- or infra-tentorial. Moreover, the underlying therapy regimes were assessed.

RESULTS

The final study cohort included 78 patients (51 females, median age 57 years), of which 11 patients (14.1%) had a repeated non-malignant cytology ('pseudomeningeosis'). In one case, this finding, a granular pleocytosis, was attributed to previous radiotherapy. Of the remaining patients, seven were receiving multimodal, immunotherapy-based therapy regimens. Patients with unsuspicious cytology had a predominantly supratentorial distribution pattern in comparison to patients with neoplastic meningitis.

CONCLUSIONS

The overall prevalence of the presence of false-positive meningeal contrast enhancement is low (< 1%) and not associated with specific imaging patterns. We hypothesize that there is a possible relationship between immunotherapy and 'pseudomeningeosis'. Therefore, in all cases with suspected neoplastic meningitis, the cerebrospinal fluid should be analyzed to confirm the diagnosis, especially in patients undergoing immunotherapy.

To Compare Diagnostic Ability of Contrast-Enhanced Three-Dimensional T1-SPACE with Three-Dimensional Fluid-Attenuated Inversion Recovery and Three-Dimensional T1-Magnetization Prepared Rapid Gradient Echo Magnetic Resonance Sequences in Patients of Meningitis

Aims:

The aim of this study is to compare postcontrast three-dimensional (3D) T1-Sampling perfection with application-optimized contrasts by using different flip angle evolutions, 3D fluid-attenuated inversion recovery (FLAIR), and 3D T1-magnetization prepared rapid gradient echo (MPRAGE) sequences in patients of meningitis.

Settings and Design:

A hospital-based cross-sectional study done in the Department of Radiodiagnosis, IGMC Shimla for a period of 1 year from June 1, 2016, to May 30, 2017.

Subjects and Methods:

A total of 30 patients suspected of meningitis underwent magnetic resonance imaging evaluation with postcontrast 3D T1-MPRAGE, 3D T1-SPACE, and 3D FLAIR sequences. The abnormal leptomeningeal enhancement was noted by two radiologists together on these sequences and scores were given to the abnormal leptomeningeal enhancement.

Statistical Analysis Used:

The sensitivity of 3D T1-SPACE, 3D T1-MPRAGE, and 3D FLAIR was calculated and compared. The level of agreement between these sequences was assessed by kappa coefficient. P < 0.05 was taken as statistically significant.

Results:

3D T1-SPACE shows superiority in meningeal enhancement along basal cisterns, Sylvian fissure and along cerebral convexities. It is also found to be better in delineating parenchymal lesions. 3D FLAIR failed to demonstrate enhancement along cerebral convexities however found to be better than 3D T1-MPRAGE in delineating enhancement along basal cisterns and Sylvian fissures. 3D T1-MPRAGE has shown subtle enhancement in basal cisterns, Sylvian fissure and along cerebral convexities. 3D T1-SPACE, 3D FLAIR, and 3D T1-MPRAGE has sensitivity of 91.67%, 66.67%, and 54.17%, respectively.

Conclusion:

Postcontrast 3D T1-SPACE sequence is an excellent tool than postcontrast 3D T1-MPRAGE and 3D FLAIR sequences in the evaluation of meningeal enhancement and depiction of additional lesions in brain parenchyma.

Central Nervous System Tuberculosis : Etiology, Clinical Manifestations and Neuroradiological Features

PURPOSE

As a result of multilateral migration and globalization in times of humanitarian crises, western countries face a possible increase in the incidence of central nervous system tuberculosis (CNS TB). The diagnosis of CNS TB is challenging and often delayed due to the manifold and often non-specific presentation of the disease. The aim of this review is to analyze and summarize imaging features and correlated clinical findings of CNS TB.

METHODS

The different manifestations of CNS TB are explained and illustrated by characteristic neuroradiological as well as neuropathological findings. An overview on diagnostic and therapeutic approaches is provided. For clarity, tables summarizing the lesion patterns, differential diagnoses and diagnostic hints are added.

RESULTS

The CNS TB can be manifested (1) diffuse as tuberculous meningitis (TBM), (2) localized as tuberculoma or (3) tuberculous abscess or (4) in extradural and intradural spinal infections. Information on clinical presentation, underlying pathology and the distinguishing features is demonstrated. The TBM is further described, which may lead to cranial nerve palsy, hydrocephalus and infarction due to associated arteritis of the basal perforators. The differential diagnoses are vast and include other infections, such as bacterial, viral or fungal meningoencephalitis, malignant causes or systemic inflammation with CNS. Complicating factors of diagnosis and treatment are HIV coinfection, multi-drug resistance and TB-associated immune reconstitution inflammatory syndrome (IRIS).

CONCLUSIONS

Neurologists and (neuro-)radiologists should be familiar with the neuroradiological presentation and the clinical course of CNS TB to ensure timely diagnosis and treatment.

Imaging in Lyme neuroborreliosis

Abstract

Lyme neuroborreliosis (LNB) is a tick-borne spirochetal infection with a broad spectrum of imaging pathology. For individuals who live in or have travelled to areas where ticks reside, LNB should be considered among differential diagnoses when clinical manifestations from the nervous system occur. Radiculitis, meningitis and facial palsy are commonly encountered, while peripheral neuropathy, myelitis, meningoencephalitis and cerebral vasculitis are rarer manifestations of LNB. Cerebrospinal fluid (CSF) analysis and serology are key investigations in patient workup. The primary role of imaging is to rule out other reasons for the neurological symptoms. It is therefore important to know the diversity of possible imaging findings from the infection itself. There may be no imaging abnormality, or findings suggestive of neuritis, meningitis, myelitis, encephalitis or vasculitis. White matter lesions are not a prominent feature of LNB. Insight into LNB clinical presentation, laboratory test methods and spectrum of imaging pathology will aid in the multidisciplinary interaction that often is imperative to achieve an efficient patient workup and arrive at a correct diagnosis. This article can educate those engaged in imaging of the nervous system and serve as a comprehensive tool in clinical cases.

Key Points

• Diagnostic criteria for LNB emphasise exclusion of an alternative cause to the clinical symptoms.

• MRI makes a crucial contribution in the diagnosis and follow-up of LNB.

• MRI may have normal findings, or show neuritis, meningitis, myelitis, encephalitis or vasculitis.

• White matter lesions are not a prominent feature of LNB.

Atypical Cerebral Manifestations of Disseminated Mycobacterium tuberculosis

Background

We investigated the patterns of cerebral manifestations in patients with underlying pulmonary or extrapulmonary tuberculosis or disseminated tuberculosis.

Materials and methods

From January 2010 to September 2016, brain magnetic resonance imaging (MRI) scans were obtained to evaluate cerebral manifestations in patients with underlying pulmonary or extrapulmonary tuberculosis. We also included patients with drug-resistant tuberculosis or disseminated tuberculosis. MRI findings of tuberculous meningitis and tuberculoma were classified as typical; other MRI findings were classified as atypical. Demographic data, risk factors, and drug regimens were collected and analyzed.

Results

Twenty-two patients were diagnosed with cerebral tuberculosis. Cerebral tuberculosis was due to hematogenous spread from pulmonary tuberculosis (10 patients), spinal tuberculosis (8 patients), disseminated tuberculosis (3 patients), and unknown causes (1 patient). There were six patients with typical MRI findings (three patients with typical meningitis involving the basal cistern and supratentorium, one patient with tuberculomas, and two patients with both) and seven patients with atypical MRI findings [five patients with evidence of early meningitis, such as high signal intensity on fluid-attenuated inversion recovery (FLAIR) along the cerebellar folia, and two patients with only hydrocephalus].

Conclusion

Besides the typical sites of meningeal involvement, overlooked findings such as FLAIR abnormalities along the cerebellar folia or hydrocephalus should be checked for early detection of cerebral tuberculosis and initiation of the appropriate treatment against disseminated tuberculosis.

Qualitative and Quantitative Comparison of Contrast-Enhanced Fluid-Attenuated Inversion Recovery, Magnetization Transfer Spin Echo, and Fat-Saturation T1-Weighted Sequences in Infectious Meningitis

Objective

To compare the contrast-enhanced fluid-attenuated inversion recovery (CE-FLAIR), the CE T1-weighted (CE-T1W) sequence with fat suppression (FS) and magnetization transfer (MT) for early detection and characterization of infectious meningitis.

Materials and Methods

Fifty patients and 10 control subjects were evaluated with the CE-FLAIR and the CE-T1W sequences with FS and MT. Qualitative assessment was done by two observers for presence and grading of abnormal leptomeningeal enhancement. Quantitative assessment included computation of net meningeal enhancement, using single pixel signal intensity software. A newly devised FLAIR based scoring system, based on certain imaging features including ventricular dilatation, ependymal enhancement, infarcts and subdural effusions was used to indicate the etiology. Data were analysed using the Student's t test, Cohen's Kappa coefficient, Pearson's correlation coefficient, the intraclass correlation coefficient, one way analysis of variance, and Fisher's exact test with Bonferroni correction as the post hoc test.

Results

The CE-FLAIR sequence demonstrated a better sensitivity (100%), diagnostic accuracy (95%), and a stronger correlation with the cerebrospinal fluid, total leukocyte count (r = 0.75), protein (r = 0.77), adenosine deaminase (r = 0.81) and blood glucose (r = -0.6) values compared to the CE-T1W sequences. Qualitative grades and quantitative meningeal enhancement on the CE-FLAIR sequence were also significantly greater than those on the other sequences. The FLAIR based scoring system yielded a diagnostic accuracy of 91.6% and a sensitivity of 96%. A strong inverse Pearson's correlation (r = -0.95) was found between the assigned score and patient's Glasgow Coma Scale at the time of admission.

Conclusion

The CE-FLAIR sequence is better suited for evaluating infectious meningitis and could be included as a part of the routine MR imaging protocol.

Utility of coronal contrast-enhanced fat-suppressed FLAIR in the evaluation of optic neuropathy and atrophy

Background and purpose

Evaluating chronic sequelae of optic neuritis, such as optic neuropathy with or without optic nerve atrophy, can be challenging on whole brain MRI. This study evaluated the utility of dedicated coronal contrast-enhanced fat-suppressed FLAIR (CE-FS-FLAIR) MR imaging to detect optic neuropathy and optic nerve atrophy.

Materials and methods

Over 4.5 years, a 3 mm coronal CE-FS-FLAIR sequence at 1.5T was added to the routine brain MRIs of 124 consecutive patients, 102 of whom had suspected or known demyelinating disease. Retrospective record reviews confirmed that 28 of these 102 had documented onset of optic neuritis >4 weeks prior to the brain MRI. These 28 were compared to the other 22 (“controls”) of the 124 patients who lacked a history of demyelinating disease or visual symptoms. Using coronal CE-FS-FLAIR, two neuroradiologists separately graded each optic nerve (n = 50 patients, 100 total nerves) as either negative, equivocal, or positive for optic neuropathy or atrophy. The scoring was later repeated.

Results

The mean time from acute optic neuritis onset to MRI was 4.1 ± 4.6 years (range 34 days-17.4 years). Per individual nerve grading, the range of sensitivity, specificity, and accuracy of coronal CE-FS-FLAIR in detecting optic neuropathy was 71.4–77.1%, 93.8–95.4%, and 85.5–89.0%, respectively, with strong interobserver (k = 0.667 − 0.678, p < 0.0001), and intraobserver (k = 0.706 − 0.763, p < 0.0001) agreement. For optic atrophy, interobserver agreement was moderate (k = 0.437 − 0.484, p < 0.0001), while intraobserver agreement was moderate-strong (k = 0.491 − 0.596, p < 0.0001).

Conclusion

Coronal CE-FS-FLAIR is quite specific in detecting optic neuropathy years after the onset of acute optic neuritis, but is less useful in detecting optic nerve atrophy.

Importance of Contrast-Enhanced Fluid-Attenuated Inversion Recovery Magnetic Resonance Imaging in Various Intracranial Pathologic Conditions

Intracranial lesions may show contrast enhancement through various mechanisms that are closely associated with the disease process. The preferred magnetic resonance sequence in contrast imaging is T1-weighted imaging (T1WI) at most institutions. However, lesion enhancement is occasionally inconspicuous on T1WI. Although fluid-attenuated inversion recovery (FLAIR) sequences are commonly considered as T2-weighted imaging with dark cerebrospinal fluid, they also show mild T1-weighted contrast, which is responsible for the contrast enhancement. For several years, FLAIR imaging has been successfully incorporated as a routine sequence at our institution for contrast-enhanced (CE) brain imaging in detecting various intracranial diseases. In this pictorial essay, we describe and illustrate the diagnostic importance of CE-FLAIR imaging in various intracranial pathologic conditions.

Magnetic resonance imaging of infectious meningitis and ventriculitis in adults

Magnetic resonance imaging findings of meningitis are usually nonspecific with respect to the causative pathogen because the brain response to these insults is similar in most cases. In this article, we will use a few representative cases to describe the characteristic magnetic resonance findings of meningitis and its complications, including ventriculitis.

Gadolinium-based MRI characterization of leptomeningeal inflammation in multiple sclerosis

OBJECTIVE

To determine the frequency and nature of leptomeningeal contrast enhancement in multiple sclerosis (MS) via in vivo 3-tesla postcontrast T2-weighted, fluid-attenuated inversion recovery (FLAIR) MRI and 7-tesla postmortem MRI-pathology correlation.

METHODS

Brain MRI, using the postcontrast T2-weighted, FLAIR technique, was prospectively collected in 299 MS cases and 37 age-matched neurologically healthy controls. Expert raters evaluated focal gadolinium enhancement in the leptomeningeal compartment. Two progressive MS cases came to autopsy after in vivo MRI characterization. Pathologic and immunohistochemical examination assessed the association of enhancement with leptomeningeal inflammation and adjacent cortical demyelination.

RESULTS

Focal contrast enhancement was detected in the leptomeningeal compartment in 74 of 299 MS cases (25%) vs 1 of 37 neurologically healthy controls (2.7%; p = 0.001). Enhancement was nearly twice as frequent (p = 0.009) in progressive MS (39/118 cases, 33%) as in relapsing-remitting MS (35/181, 19%). Enhancing foci generally remained stable throughout the evaluation period (up to 5.5 years). Pathology showed perivascular lymphocytic and mononuclear infiltration in the enhancing areas in association with flanking subpial cortical demyelination.

CONCLUSION

Leptomeningeal contrast enhancement occurs frequently in MS and is a noninvasive, in vivo marker of inflammation and associated subpial demyelination. It might therefore enable testing of new treatments aimed at eliminating this inflammation and potentially arresting progressive MS.

Differentiation of Leptomeningeal and Vascular Enhancement on Post-contrast FLAIR MRI Sequence: Role in Early Detection of Infectious Meningitis

OBJECTIVE

To qualitatively and quantitatively differentiate leptomeningeal and vascular enhancement on Post-contrast Fluid Attenuated Inversion Recovery (PCFLAIR) sequence compared to post-contrast T1-weighted (PCT1W) sequence with fat suppression (FS) and evaluate its role in early detection of infectious meningitis.

MATERIALS AND METHODS

Thirty-one patients with diagnosis of meningitis were evaluated with pre and post-contrast FLAIR and T1-weighted sequences with fat suppression (FS). Qualitative assessment was done by two observers for presence, absence or equivocal status of leptomeningeal enhancement. Further, quantitative estimation of single pixel signal intensities (SPSI) for meningeal and vascular enhancement was undertaken. A statistical comparison was performed using Kappa coefficient and t-test.

RESULTS

The overall qualitative accuracy was 90.3% for PCFLAIR compared to 54.8% for PCT1W with FS sequence. PCFLAIR was found to be 100% accurate in the detection of tubercular and pyogenic meningitis and 70% accurate in the detection of viral meningitis while PCT1W with FS sequence showed the corresponding accuracy to be 76.2% and 0% respectively. Both observers rated PCFLAIR images better than PCT1W with FS at detecting meningitis (p<0.05). The quantitative assessment revealed that the SPSI difference between the average meningeal and vascular enhancement on PCFLAIR was significantly greater than that on PCT1W with FS sequence (t= 6.31, p<0.01).

CONCLUSION

PCFLAIR sequence has insignificant component of vascular enhancement compared to meningeal enhancement. This makes meningeal inflammation easily discernable and aids in early detection of infectious meningitis.

Central nervous system tuberculosis: an imaging-focused review of a reemerging disease

Central nervous system (CNS) tuberculosis is a potentially life threatening condition which is curable if the correct diagnosis is made in the early stages. Its clinical and radiologic manifestations may mimic other infectious and noninfectious neurological conditions. Hence, familiarity with the imaging presentations of various forms of CNS tuberculosis is essential in timely diagnosis, and thereby reducing the morbidity and mortality of this disease. In this review, we describe the imaging characteristics of the different forms of CNS tuberculosis, including meningitis, tuberculoma, miliary tuberculosis, abscess, cerebritis, and encephalopathy.

Use of contrast-enhanced fluid-attenuated inversion recovery sequence to detect brain lesions in dogs and cats

Background

The diagnostic value of a contrast‐enhanced T2‐weighted FLAIR sequence (ceFLAIR) in brain imaging is unclear.

Hypothesis/Objectives

That the number of brain lesions detected with ceFLAIR would be no greater than the sum of lesions detected with nFLAIR and ceT1W sequence.

Animals

One hundred and twenty‐nine animals (108 dogs and 21 cats) undergoing magnetic resonance imaging (MRI) of the head between July 2010 and October 2011 were included in the study.

Methods

A transverse ceFLAIR was added to a standard brain MRI protocol. Presence and number of lesions were determined based on all available MRI sequences by 3 examiners in consensus and lesion visibility was evaluated for nFLAIR, ceFLAIR, and ceT1W sequences.

Results

Eighty‐three lesions (58 intra‐axial and 25 extra‐axial) were identified in 51 patients. Five lesions were detected with nFLAIR alone, 2 with ceT1W alone, and 1 with ceFLAIR alone. Significantly higher numbers of lesions were detected using ceFLAIR than nFLAIR (76 versus 67 lesions; P = 0.04), in particular for lesions also detected with ceT1W images (53 versus 40; P =.01). There was no significant difference between the number of lesions detected with combined nFLAIR and ceT1W sequences compared to those detected with ceFLAIR (82 versus 76; P =.25).

Conclusion and Clinical Importance

Use of ceFLAIR as a complementary sequence to nFLAIR and ceT1W sequences did not improve the detection of brain lesions and cannot be recommended as part of a routine brain MRI protocol in dogs and cats with suspected brain lesions.

Diagnostic Accuracy of Contrast-Enhanced FLAIR Magnetic Resonance Imaging in Diagnosis of Meningitis Correlated with CSF Analysis

Purpose. To determine the diagnostic accuracy of contrast enhanced FLAIR sequence of MRI brain in the diagnosis of meningitis. Subjects and Methods. A prospective study of 57 patients with signs and symptoms of meningitis, referred to the radiology department for MRI examination. Out of these, there were 30 males and 27 females. They underwent MRI brain with contrast including postcontrast T1W and FLAIR sequences. Cerebrospinal fluid (CSF) analysis obtained by lumbar puncture after MRI was considered the “reference standard” against which MRI findings were compared. Results. Of 57 patients, 50 were diagnosed as having meningitis on subsequent CSF analysis. Out of these 50, 49 were positive on postcontrast FLAIR images and 34 were positive on postcontrast T1W images. One patient was labeled false positive as CSF analysis showed malignant cells (leptomeningeal carcinomatosis). In the diagnosis of meningitis, the sensitivity of postcontrast FLAIR sequence was 96% and specificity 85.71%, whereas the sensitivity of postcontrast T1W sequence was 68% and specificity 85.71%. Conclusion. Contrast-enhanced FLAIR sequence is more sensitive and specific than contrast-enhanced T1W sequence in the diagnosis of meningitis. It should be routinely used in suspected cases of meningitis.

Pediatric intracranial infections

Infection of the central nervous system (CNS) in children is an important entity and early recognition is paramount to avoid long-term brain injury, especially in very young patients. The causal factors are different in children compared with adults and so are the clinical presentations. However, imaging features of CNS infection show similar features to those of adults. This article reviews some of the common types of pediatric infections, starting with the congenital (or in utero) infections followed by bacterial infections of the meninges and brain parenchyma.

Significance of radio-pathological correlations: differentiating severe central nervous system infection from acute embolic infarction

We describe two educational autopsy cases of severe central nervous system (CNS) infection and septic emboli, such cases having been difficult to differentiate from acute infarctions via emergency MR imaging studies. We briefly discuss the pathology and MR findings along with radiopathological correlation.