Pediatric multiple sclerosis: from clinical basis to imaging spectrum and differential diagnosis.

Pediatric multiple sclerosis (MS) deserves special attention because of its impact on cognitive function and development. Although knowledge regarding pediatric MS has rapidly increased, understanding the peculiarities of this population remains crucial for disease management. There is limited expertise about the efficacy and safety of current disease-modifying agents. Although pathophysiology is not entirely understood, some risk factors and immunological features have been described and are discussed herein. While the revised International Pediatric MS Study Group diagnostic criteria have improved the accuracy of diagnosis, the recently revised McDonald criteria also offer some new insights into the pediatric population. It is fundamental that radiologists have strong knowledge about the vast spectrum of demyelinating disorders that can occur in childhood to ensure appropriate diagnosis and provide early treatment.

Imaging Patterns of Toxic and Metabolic Brain Disorders.

Toxic and metabolic brain disorders are relatively uncommon diseases that affect the central nervous system, but they are important to recognize as they can lead to catastrophic outcomes if not rapidly and properly managed. Imaging plays a key role in determining the most probable diagnosis, pointing to the next steps of investigation, and providing prognostic information. The majority of cases demonstrate bilateral and symmetric involvement of structures at imaging, affecting the deep gray nuclei, cortical gray matter, and/or periventricular white matter, and some cases show specific imaging manifestations. When an appropriate clinical situation suggests exogenous or endogenous toxic effects, the associated imaging pattern usually indicates a restricted group of diagnostic possibilities. Nonetheless, toxic and metabolic brain disorders in the literature are usually approached in the literature by starting with common causal agents and then reaching imaging abnormalities, frequently mixing many different possible manifestations. Conversely, this article proposes a systematic approach to address this group of diseases based on the most important imaging patterns encountered in clinical practice. Each pattern is suggestive of a most likely differential diagnosis, which more closely resembles real-world scenarios faced by radiologists. Basic pathophysiologic concepts regarding cerebral edemas and their relation to imaging are introduced-an important topic for overall understanding. The most important imaging patterns are presented, and the main differential diagnosis for each pattern is discussed. Online supplemental material is available for this article. ©RSNA, 2019.

Thrombus Imaging Characteristics and Outcomes in Acute Ischemic Stroke Patients Undergoing Endovascular Treatment.

Background and Purpose- Thrombus imaging characteristics have been reported to be useful to predict functional outcome and reperfusion in acute ischemic stroke. However, conflicting data about this subject exist in patients undergoing endovascular treatment. Therefore, we aimed to evaluate whether thrombus imaging characteristics assessed on computed tomography are associated with outcomes in patients with acute ischemic stroke treated by endovascular treatment. Methods- The MR CLEAN (Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute Ischemic Stroke in the Netherlands) Registry is an ongoing, prospective, and observational study in all centers performing endovascular treatment in the Netherlands. We evaluated associations of thrombus imaging characteristics with the functional outcome (modified Rankin Scale at 90 days), mortality, reperfusion, duration of endovascular treatment, and symptomatic intracranial hemorrhage using univariable and multivariable regression models. Thrombus characteristics included location, clot burden score (CBS), length, relative and absolute attenuation, perviousness, and distance from the internal carotid artery terminus to the thrombus. All characteristics were assessed on thin-slice (≤2.5 mm) noncontrast computed tomography and computed tomography angiography, acquired within 30 minutes from each other. Results- In total, 408 patients were analyzed. Thrombus with distal location, higher CBS, and shorter length were associated with better functional outcome (adjusted common odds ratio, 3.3; 95% CI, 2.0-5.3 for distal M1 occlusion compared with internal carotid artery occlusion; adjusted common odds ratio, 1.15; 95% CI, 1.07-1.24 per CBS point; and adjusted common odds ratio, 0.96; 95% CI, 0.94-0.99 per mm, respectively) and reduced duration of endovascular procedure (adjusted coefficient B, -14.7; 95% CI, -24.2 to -5.1 for distal M1 occlusion compared with internal carotid artery occlusion; adjusted coefficient B, -8.5; 95% CI, -14.5 to -2.4 per CBS point; and adjusted coefficient B, 7.3; 95% CI, 2.9-11.8 per mm, respectively). Thrombus perviousness was associated with better functional outcome (adjusted common odds ratio, 1.01; 95% CI, 1.00-1.02 per Hounsfield units increase). Distal thrombi were associated with successful reperfusion (adjusted odds ratio, 2.6; 95% CI, 1.4-4.9 for proximal M1 occlusion compared with internal carotid artery occlusion). Conclusions- Distal location, higher CBS, and shorter length are associated with better functional outcome and faster endovascular procedure. Distal thrombus is strongly associated with successful reperfusion, and a pervious thrombus is associated with better functional outcome.

Imaging of Creutzfeldt-Jakob Disease: Imaging Patterns and Their Differential Diagnosis.

Diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD) remains a challenge because of the large variability of the clinical scenario, especially in its early stages, which may mimic several reversible or treatable disorders. The molecular basis of prion disease, as well as its brain propagation and the pathogenesis of the illness, have become better understood in recent decades. Several reports have listed recognizable clinical features and paraclinical tests to supplement the replicable diagnostic criteria in vivo. Nevertheless, we lack specific data about the differential diagnosis of CJD at imaging, mainly regarding those disorders evolving with similar clinical features (mimicking disorders). This review provides an update on the neuroimaging patterns of sCJD, emphasizing the relevance of magnetic resonance (MR) imaging, summarizing the clinical scenario and molecular basis of the disease, and highlighting clinical, genetic, and imaging correlations in different subtypes of prion diseases. A long list of differential diagnoses produces a comprehensive pictorial review, with the aim of enabling radiologists to identify typical and atypical patterns of sCJD. This review reinforces distinguishable imaging findings and confirms diffusion-weighted imaging (DWI) features as pivotal in the diagnostic workup of sCJD, as these findings enable radiologists to reliably recognize this rare but invariably lethal disease. A probable diagnosis is justified when expected MR imaging patterns are demonstrated and CJD-mimicking disorders are confidently ruled out. ©RSNA, 2017.

"Ears of the lynx" sign in a marchiafava-bignami patient: structural basis and fiber-tracking DTI contribution to the understanding of this imaging abnormality.

The "ears of the lynx" sign was previously reported as a neuroimaging finding observed in patients with autosomal recessive hereditary spastic paraplegia in association with a thin corpus callosum (ARHSP-TCC). We report a patient with a chronic form of Marchiafava-Bignami disease (MBD) that presented with this imaging feature. Diffusion tensor imaging (DTI) and fiber-tracking data support that this finding is a consequence of the structural derangement, which enlarges a preexisting border zone of the bundles of fibers from the corpus callosum (CC) genu to the forceps minor and anterior corona radiata. Therefore, we assume that despite their pathological differences, damage to the anterior portion of the CC is responsible for the imaging similarities between MBD and ARHSP-TCC.

Diffusion tensor MR imaging in neurofibromatosis type 1: expanding the knowledge of microstructural brain abnormalities.

BACKGROUND: Neurofibromatosis type 1 (NF1) is a hereditary disease with a dominant autosomal pattern. In children and adolescents, it is frequently associated with the appearance of T2-weighted hyperintensities in the brain's white matter. MRI with diffusion tensor imaging (DTI) is used to detect white matter abnormalities by measuring fractional anisotropy (FA). OBJECTIVE: This study employed DTI to evaluate the relationship between FA patterns and the findings of T2 sequences, with the aim of improving our understanding of anatomical changes and microstructural brain abnormalities in individuals with NF1. MATERIALS AND METHODS: Forty-four individuals with NF1 and 20 control subjects were evaluated. The comparative analysis of FA between NF1 and control groups was based on four predetermined anatomical regions of the brain hemispheres (basal ganglia, cerebellum, pons, thalamus) and related the presence or absence of T2-weighted hyperintensities in the brain, which are called unidentified bright objects (UBOs). RESULTS: The FA values between the groups demonstrated statistically significant differences (P ≤ 0.05) for the cerebellum and thalamus in patients with NF1, independent of the occurrence of UBOs. CONCLUSIONS: Diffusion tensor MR imaging confirms the influence of UBOs in the decrease of FA values in this series of patients with NF1. Additionally, this technique allows the characterization of microstructural abnormalities even in some brain regions that appear normal in conventional MR sequences.

Cranial vault lymphoma: a systematic review of five patients.

Bone involvement is a common finding in many types of lymphoma (Clin Oncol 9(3): 195-196, 1997). However, cranial vault affliction has been regarded as an exceedingly rare presentation, particularly in the case of primary lymphoma (J Neurosurg 108(5): 1018-1020, 2008). Our objective is to describe a series of five immunocompetent patients with histologically confirmed cranial vault lymphoma (CVL), and to conduct a systematic review of the current literature. Our review points out identical imaging patterns in most of the lesions for all reported CVL cases, despite their different histological subtypes. This typical pattern can be seen on computed tomography (CT) scans and magnetic resonance imaging (MRI) as an expansive tumor that affects all three compartments of the cranial vault, including the scalp, skull bone, and pachymeninges, even in the absence of osteolysis. We argue that the absence of osteolysis might enhance diagnostic capability. In the appropriate clinical setting, these features represent important disease characteristics that may help with an earlier diagnosis. Large B-cell lymphoma was the most common subtype of primary CVL.

MR cerebral blood volume maps correlated with vascular endothelial growth factor expression and tumor grade in nonenhancing gliomas.

BACKGROUND AND PURPOSE: Relative cerebral blood volume (rCBV) measurements derived from perfusion-weighted imaging (PWI) may be useful to evaluate angiogenesis and preoperatively estimate the grade of a glioma. We hypothesized that rCBV is correlated with vascular endothelial growth factor (VEGF) expression as marker of the angiogenic stimulus in presumed supratentorial low-grade gliomas (LGGs). METHODS: From February 2001 to February 2004, we examined 20 adults (16 men, four women; mean age 36 years; range, 23-60 years) with suspected (nonenhancing) supratentorial LGG on conventional MR imaging. Preoperative MR imaging used a dynamic first-pass gadolinium-enhanced, spin-echo echo-planar PWI. In heterogeneous tumors, we performed stereotactic biopsy in the high-perfusion areas before surgical resection. Semiquantitative grading of VEGF immunoreactivity was applied. RESULTS: Nine patients had diffuse astrocytomas (World Health Organization grade II), and 11 had other LGG and anaplastic gliomas. In patients with heterogeneous tumors on PWI, the high-rCBV focus had areas of oligodendroglioma or anaplastic astrocytoma on stereotactic biopsy, whereas the surgical specimens were predominantly astrocytomas. Anaplastic gliomas had high rCBV ratios and positive VEGF immunoreactivity. Diffuse astrocytomas had negative VEGF expression and mean rCBV values significantly lower than those of the other two groups. Three diffuse astrocytomas had positive VEGF immunoreactivity and high rCBV values. CONCLUSION: Our results confirmed the correlation among rCBV measurements, VEGF expression, and histopathologic grade in nonenhancing gliomas. PWI may add useful data to the preoperative assessment of nonenhancing gliomas. Its contribution in predicting tumor behavior and patient prognosis remains to be determined.

Evidence of acute ischemic tissue change in transient global amnesia in magnetic resonance imaging: case report and literature review.

Transient global amnesia is a benign syndrome of sudden-onset alteration of behavior with temporary dysfunction of anterograde and recent retrograde memory. Its neural substrates remain uncertain. Possible causes include ischemia, migraine, and epilepsy. The authors report a case of a 62-year-old man with a transient attack of memory disturbance, suggestive of transient global amnesia, in which magnetic resonance imaging performed 48 hours after onset showed left mesial temporal lobe signal changes on diffusion-weighted imaging and fluid-attenuated inversion recovery images. The findings and a literature review lend further support to the ischemic pathogenesis of transient global amnesia as a possible etiology, and underscore the role of diffusion-weighted imaging in the diagnosis of this condition.

Stereotactic biopsy guidance in adults with supratentorial nonenhancing gliomas: role of perfusion-weighted magnetic resonance imaging.

OBJECT: The. diagnosis of low-grade glioma (LGG) cannot be based exclusively on conventional magnetic resonance (MR) imaging studies, and target selection for stereotactic biopsy is a crucial issue given the high risk of sampling errors. The authors hypothesized that perfusion-weighted imaging could provide information on the microcirculation in presumed supratentorial LGGs. METHODS: All adult patients with suspected (nonenhancing) supratentorial LGGs on conventional MR imaging between February 2001 and February 2004 were included in this study. Preoperative MR imaging was performed using a dynamic first-pass gadopentate dimeglumine-enhanced spin echo-echo planar perfusion-weighted sequence, and the tumors' relative cerebral blood volume (rCBV) measurements were expressed in relation to the values observed in contralateral white matter. In patients with heterogeneous tumors a stereotactic biopsy was performed in the higher perfusion areas before resection. Among 21 patients (16 men and five women with a mean age of 36 years, range 23-60 years), 10 had diffuse astrocytomas (World Health Organization Grade II) and 11 had other LGGs and anaplastic gliomas. On perfusion-weighted images demonstrating heterogeneous tumors, areas of higher rCBV focus were found to be oligodendrogliomas or anaplastic astrocytomas on stereotactic biopsy; during tumor resection, however, specimens were characterized predominantly as astrocytomas. Diffuse astrocytomas were associated with significantly lower mean rCBV values compared with those in the other two lesion groups (p < 0.01). The rCBV ratio cutoff value that permitted better discrimination between diffuse astrocytomas and the other lesion groups was 1.2 (80% sensitivity and 100% specificity). CONCLUSIONS: Perfusion-weighted imaging is a feasible method of reducing the sampling error in the histopathological diagnosis of a presumed LGG, particularly by improving the selection of targets for stereotactic biopsy.

Detection of corticospinal tract compromise in amyotrophic lateral sclerosis with brain MR imaging: relevance of the T1-weighted spin-echo magnetization transfer contrast sequence.

BACKGROUND AND PURPOSE: Hyperintensity in the posterior limb of the internal capsule at T2-weighted MR imaging, consistent with corticospinal tract (CST) degeneration, is described in amyotrophic lateral sclerosis (ALS). However, the lack of specific tests or biological markers hinders confirmation of the diagnosis, especially in the early stages. We investigated the CST in ALS with MR imaging. METHODS: We examined 25 patients (14 men, 11 women; mean age, 49.1 years; range, 29-68 years) and 21 age- and sex-matched control subjects without upper motor neuron signs. According to the revised El Escorial criteria, 22 patients had definite ALS; two, probable ALS; and one, suspected ALS. Fluid-attenuated inversion recovery (FLAIR; TR/TE/TI, 11,000/140/2600) and T1-weighted spin-echo (SE)/magnetization transfer contrast-enhanced (MTC; TR/TE, 510/12) imaging was performed at 1 T. Two experienced neuroradiologists blinded to the patients' history independently evaluated the CST. RESULTS: T1-weighted SE MTC imaging allowed visualization of the CST in both patients and control subjects. T1-weighted SE MTC images showed hypointensity along the CST and bilateral subcortical regions of the precentral gyri in all control subjects and hyperintensity in 80% of patients with ALS (P < .05). FLAIR images showed hyperintensity in these areas in both groups, with no significant difference. CONCLUSION: T1-weighted SE MTC imaging is sensitive and accurate in depicting CST lesions in ALS, whereas FLAIR imaging is not. T1-weighted SE MTC imaging is useful in diagnosing ALS by showing hyperintense areas along the CST, which separates patients from control subjects. This sequence should be included in the workup of patients with weakness and pyramidal signs.

Reversal of parkinsonism and portosystemic encephalopathy following embolization of a congenital intrahepatic venous shunt: brain MR imaging and 1H spectroscopic findings.

Parkinsonism and portosystemic encephalopathy (PSE) are cerebral disorders associated with motor and neuropsychological dysfunctions that may occur in patients with chronic liver disease. We describe a patient with parkinsonism and neuroradiologic and 1H spectroscopic findings of PSE associated with a large congenital intrahepatic portosystemic venous shunt. Chronic liver disease was absent. After endovascular treatment, we documented a progressive reversal of parkinsonism and PSE on the basis of clinical, neuroradiologic, and spectroscopic criteria.

Relationship between the concentration of supplemental oxygen and signal intensity of CSF depicted by fluid-attenuated inversion recovery imaging.

BACKGROUND AND PURPOSE: Prior reports have described increased signal intensity (SI) of CSF on fluid-attenuated inversion recovery (FLAIR) images of anesthetized patients receiving 100% O(2). This appearance can simulate that of diseases. We evaluated the relationship between the concentration of inhaled O(2) and the development of increased SI of CSF on FLAIR images. METHODS: FLAIR was performed in 25 healthy volunteers breathing room air and 100% O(2) through a face mask for 5, 10, and 15 minutes. MR imaging, including FLAIR imaging, was performed in 52 patients with no potential meningeal abnormalities under general anesthesia: 21 received an equal mixture of N(2)O and O(2), and 31 received 100% O(2). The SI of CSF in volunteers and patients was graded in several locations by using a three-point scale. RESULTS: SI of CSF significantly increased (P <.05) in various locations, in both volunteers and patients breathing 100% O(2), when compared with SI in the same volunteers breathing room air. Hyperintensity of CSF was not significantly different in volunteers receiving 100% O(2) through a face mask compared with anesthetized patients receiving 100% O(2) through a laryngeal airway or an endotracheal tube. No significant increase in SI occurred in patients receiving 50% O(2), when compared with the SI of volunteers breathing room air. CONCLUSION: Supplemental oxygen at 100% is a main cause of artifactual CSF hyperintensity on FLAIR images, regardless of the anesthetic drug used. This artifact does not develop when 50% O(2) is administered.

Clinical, laboratory, psychiatric and magnetic resonance findings in patients with Sydenham chorea.

The objective of this study was to determine the clinical and laboratory characteristics, psychiatric manifestations and magnetic resonance imaging (MRI) findings in children and adolescents with Sydenham chorea (SyC). The imaging examination was repeated 1 year after the acute phase of SyC. There were 19 patients with a mean age of 11.7 years and a predominance of females (79%);68% had generalized chorea and 53% moderate chorea. SyC presented as an isolated manifestation in 74%. No association between SyC and obsessive-compulsive disorder was found. Mental health problems were present in 45% of the patients. MRI analysis revealed persistent alterations in the caudate nucleus in three patients (16%), who presented recurrent episodes of chorea during the study. In one patient, MRI revealed the presence of nodular heteropathy close to the caudate nucleus region. We conclude that attention problems can be associated with acute clinical features of SyC and persistent alterations in the basal nuclei, evidenced by MRI, can be found in some patients who tend to suffer prolonged attacks and a greater number of recurrences.