The contribution of magnetic resonance imaging in the differential diagnosis of the damage of the cerebral hemispheres

There are presently many magnetic resonance (MR) measures that can aid the assessment of damage to the brain. The conventional measures include T2 lesion volume, T1 enhanced lesion volume, and brain atrophy. Newer methodologies include magnetization transfer measures and proton spectroscopy. These methods have the potential for improving the specificity of MR with respect to the underlying pathology. MR spectroscopy offers the ability to quantitate the component of axonal loss in multiple sclerosis. MR techniques can be implemented to assess the effectiveness of treatment algorithms.     

Assessment of optic nerve damage in multiple sclerosis using magnetic resonance imaging

The MR imaging-based assessment of the optic nerve in optic neuritis and multiple sclerosis provides information that is complementary to clinical and electrophysiological methods. The standard and more tissue destruction specific methods can be used in strategies to measure treatment efficacy and for understanding the mechanisms of relapse, recovery, and failure of recovery.     

The contribution of magnetic resonance imaging to the diagnosis of multiple sclerosis.

MRI is very sensitive in showing MS lesions throughout the CNS. Using MRI for diagnostic purposes, however useful, is a complex issue because of limited specificity of findings and a variety of options as to when, how, and which patients to examine. Comparability of data and a common view regarding the impact of MRI are needed. Following a review of the typical appearance and pattern of MS lesions including differential diagnostic considerations, we suggest economic MRI examination protocols for the brain and spine. Recommendations for referral to MRI consider the need to avoid misdiagnosis and the probability of detecting findings of diagnostic relevance. We also suggest MRI classes of evidence for MS to determine the diagnostic weight of findings and their incorporation into the clinical evaluation. These proposals should help to optimize and standardize the use of MRI in the diagnosis of MS.     

Magnetic resonance imaging of the optic nerve in optic neuritis

Magnetic resonance imaging (MRI) of the optic nerves using the STIR (short inversion time inversion recovery) sequence was performed in 37 adult patients with a recent or past attack of optic neuritis. MRI revealed high-signal regions in 84% of symptomatic and 20% of asymptomatic nerves. The mean longitudinal extent of lesions was 1 cm. Slow or poor visual recovery was associated with more extensive lesions, or lesions within the optic canal. Disk swelling was usually associated with anterior lesions but also occurred with lesions in the canal. Visual evoked potentials were even more sensitive than MRI in detecting lesions and are still the investigation of choice in suspected demyelinating disease involving the optic nerve.     

Visual evoked potential is superior to triple dose magnetic resonance imaging in the diagnosis of optic nerve involvement

The aim of this study was to evaluate whether VEP is sensitive to optic neuritis (ON) when compared with triple dose orbital MRI. Twenty-four relapsing-remitting MS (RRMS) patients were included in the study. Group I (n = 10) patients with acute ON, Group II (n = 8): patients presenting with a current relapse who had the history of ON in the previous relapses. Group III (n = 6): patients presenting with a current relapse but with no history of ON. Neuro-ophtalmological evaluation. VEP investigation and orbital MRI with triple dose (0.3 mmol/kg) gadolinium (Gd) were carried out for all. VEP was found to be 70% sensitive and 12.5% specific to the acute ON, whereas orbital MRI with triple dose Gd was 70% sensitive and 100% specific. In chronic ON, the sensitivity of orbital MRI is 0%, whereas the VEP is still 75% sensitive to chronic optic nerve involvement and can distinguish the pathology 100% specifically. In conclusion, orbital MRI with triple dose Gd is not more sensitive than VEP in determining the acute optic nerve pathologies but it is a 100% specific method. The results suggest that VEP is superior to the orbital MRI in determining the chronic optic nerve involvement.     

Optic nerve enhancement on magnetic resonance imaging in arteritic ischemic optic neuropathy.

Although optic nerve enhancement may be seen in magnetic resonance imaging of radiation-induced ischemic optic neuropathy, similar enhancement in ischemic optic neuropathy has not been previously reported in the English-language neuroophthalmologic literature. We report three cases of optic nerve enhancement in biopsy-proven arteritic ischemic optic neuropathy. Clinicians should consider giant cell arteritis in the differential diagnosis of an optic neuropathy with optic nerve enhancement on magnetic resonance imaging.     

Intraorbital optic nerve signal hyperintensity on magnetic resonance imaging sequences in perioperative hypotensive ischemic optic neuropathy.

A 61-year-old man experienced severe bilateral posterior ischemic optic neuropathy after cardiac bypass surgery. Routine magnetic resonance imaging sequences were normal, but diffusion-weighted and fluid-attenuated inversion recovery (FLAIR) sequences showed abnormal hyperintensity within both intra-orbital optic nerves. This imaging abnormality has not been previously reported in this setting.     

The contribution of MRI in the differential diagnosis of posterior fossa damage

In multiple sclerosis patients, magnetic resonance imaging (MRI) frequently detects lesions in the brain stem and cerebellum. However various pathologies that have a predelection to occur in posterior fossa parenchyma may share similar features with inflammatory-demyelinating lesions. In this paper, we review the contribution of MRI to the differential diagnosis of posterior fossa pathology. Vascular lesions due to chronic hypoperfusion and arteriolosclerosis or occlusion of the main supplying arteries of the posterior circulation leading to acute infarction frequently produce characteristic pontine or cerebellar lesions. Neoplastic disease, in particular pontine gliomas in younger patients may have similar MRI features and may be difficult to distinguish from inflammatory-demyelinating lesions. Central pontine myelinolysis usually occurs in severely ill patients but the pontine MRI changes have an overlapping profile with inflammatory demyelination. Diffuse axonal injury of the midbrain and brainstem after head trauma and atrophy of posterior fossa structures in degenerative diseases may appear similar on MRI to tissue changes also seen frequently in MS. Analysis of the MRI appearance and clinical information is most often useful to narrow the fairly long list of differential diagnoses of posterior fossa pathology.     

Optic nerve enhancement on orbital magnetic resonance imaging in Leber's hereditary optic neuropathy.

An 18-year-old man with Leber's hereditary optic neuropathy and bilateral visual loss had optic nerve enhancement on T1-weighted orbital fat-suppressed magnetic resonance imaging. To our knowledge, this is the first reported case of optic nerve enhancement on orbital magnetic resonance imaging in Leber's hereditary optic neuropathy.     

Clinical and magnetic resonance imaging in optic neuritis

We found 23 of 48 patients (48%) with isolated monosymptomatic optic neuritis (ON) to have 1 to several brain lesions by MRI. All the brain lesions were clinically silent and had characteristics consistent with multiple sclerosis (MS). During 4 years of follow-up, 9 patients (19%) developed definite MS on clinical grounds. Six of the converting patients had abnormal MRIs; the other 3 had MRIs that were normal both initially (when they had ON only) and when repeated after they had developed MS. The other 17 patients with abnormal MRIs have not developed symptoms or signs of MS during follow-up. Thus, an abnormal MRI does not auger development of clinical MS within a mean of 4 years, nor does a normal MRI protect against development of disseminated disease. It is not prudent to give a patient with isolated monosymptomatic ON the diagnosis of MS (probable or definite) because of an abnormal MRI (with or without other laboratory abnormalities).     

Magnetization transfer magnetic resonance imaging of the brain, spinal cord, and optic nerve

Magnetic resonance imaging is highly sensitive in revealing CNS abnormalities associated with several neurological conditions, but lacks specificity for their pathological substrates. In addition, MRI does not allow evaluation of the presence and extent of damage in regions that appear normal on conventional MRI sequences and that postmortem studies have shown to be affected by pathology. Quantitative MR-based techniques with increased pathological specificity to the heterogeneous substrates of CNS pathology have the potential to overcome such limitations. Among these techniques, one of the most extensively used for the assessment of CNS disorders is magnetization transfer MRI (MT-MRI). The application of this technique for the assessment of damage in macroscopic lesions, in normal-appearing white and gray matter, and in the spinal cord and optic nerve of patients with several neurological conditions is providing important in vivo information—dramatically improving our understanding of the factors associated with the appearance of clinical symptoms and the accumulation of irreversible disability. MT-MRI also has the potential to contribute to the diagnostic evaluation of several neurological conditions and to improve our ability to monitor treatment efficacy in experimental trials.     

Retinal and optic nerve magnetic resonance diffusion-weighted imaging in acute non-arteritic central retinal artery occlusion

ObjectivesDiffusion weighted imaging hyperintensity (DWI-H) has been described in the retina and optic nerve during acute central retinal artery occlusion (CRAO). We aimed to determine whether DWI-H can be accurately identified on standard brain magnetic resonance imaging (MRI) in non-arteritic CRAO patients at two tertiary academic centers.Materials and methodsRetrospective cross-sectional study that included all consecutive adult patients with confirmed acute non-arteritic CRAO and brain MRI performed within 14 days of CRAO. At each center, two neuroradiologists masked to patient clinical data reviewed each MRI for DWI-H in the retina and optic nerve, first independently then together. Statistical analysis for inter-rater reliability and correlation with clinical data was performed.ResultsWe included 204 patients [mean age 67.9±14.6 years; 47.5% females; median time from CRAO to MRI 1 day (IQR 1-4.3); 1.5 T in 127/204 (62.3%) and 3.0 T in 77/204 (37.7%)]. Inter-rater reliability varied between centers (κ = 0.27 vs. κ = 0.65) and was better for retinal DWI-H. Miss and error rates significantly differed between neuroradiologists at each center. After consensus review, DWI-H was identified in 87/204 (42.6%) patients [miss rate 117/204 (57.4%) and error rate 11/87 (12.6%)]. Significantly more patients without DWI-H had good visual acuity at follow-up (p = 0.038).ConclusionsIn this real-world case series, differences in agreement and interpretation accuracy among neuroradiologists limited the role of DWI-H in diagnosing acute CRAO on standard MRI. DWI-H was identified in 42.6% of patients and was more accurately detected in the retina than in the optic nerve. Further studies are needed with standardized novel MRI protocols.     

磁共振扩散张量成像技术在外伤性视神经病中应用研究

目的 探讨磁共振扩散张量成像技术在评价外伤性视神经病中的作用. 方法选择6例单侧外伤性视神经病患者,采用磁共振扩散张蛩成像技术检测双侧视神经.应用DTV2和Volume One 1.44软件测量视神经的部分各向异性值、平均表观扩散系数,并进行损伤眼和正常眼的自身对比;应用神经白质纤维柬追踪技术显示视神经的空间完整性和连续情况.结果 所有患者眶内段视神经显示良好,2例患者双侧管内段显示欠佳.6例患者损伤眼眶内段视神经部分各向异性平均值较正常眼明显下降,分别为0.244±0.067和0.452±0.053,差异有统计学意义(P=0.000);平均表观扩散系数平均值较正常眼明显上升,分别为(1.417±0.121)×10<'-3>mm<'2>/s和(1.087±0.118)×10<'-3>mm<'2>/s,差异有统计学意义(P=0.003).4例患者可以获得用于评估双侧视神经空间连接情况的扩散张量纤维束成像图,损伤眼和正常眼之间存在明显差异.结论磁共振扩散张量成像技术能够为评估外伤性视神经病的视神经纤维病理情况提供有价值的信息.     

The utility of magnetic resonance imaging in evaluating peripheral nerve disorders

The evaluation of peripheral nerve injuries has traditionally relied primarily on information gained from the clinical history, physical examination, and electrodiagnostic testing. Taken together, all of this clinical and diagnostic information often allows one to determine the location and severity of the underlying peripheral nerve problem. However, it may not be sufficient in diagnosing a focal entrapment neuropathy superimposed upon a more generalized peripheral neuropathy; localizing a focal lesion along a long segment of nerve which may be difficult to assess accurately with electrodiagnostic studies; distinguishing early between an axonotmetic grade of injury, which can recover through axonal regeneration, and a neurotmetic grade which cannot and therefore may benefit from a surgical exploration and repair procedure; and noninvasively diagnosing and determining the surgical resectability of peripheral nerve mass lesions such as tumors. The goal of this review is to illustrate how standard and evolving magnetic resonance imaging techniques can provide additional information in dealing with some of these problems.     

Magnetic resonance imaging in optic nerve lesions with multiple sclerosis

Magnetic resonance imaging (MRI) of the optic nerves was performed in 10 patients with multiple sclerosis (MS) using short inversion time inversion recovery (STIR) pulse sequences, and the results were compared with the visual evoked potentials (VEP). The 10 patients had optic neuritis in the chronic or remitting phase together with additional symptoms or signs allowing a diagnosis of clinically definite or probable MS. Sixteen optic nerves were clinically affected and 4 were unaffected. MRI was performed using a 0.5 tesla superconducting unit, and multiple continuous 5 mm coronal and axial STIR images were obtained. A lesion was judged to be present if a focal or diffuse area of increased signal intensity was detected in the optic nerve. In VEP, a delay in peak latency or no P 100 component was judged to be abnormal. With regard to the clinically affected optic nerves, MRI revealed a region of increased signal intensity in 14/16 (88%) and the VEP was abnormal in 16/16 (100%). In the clinically unaffected optic nerves, MRI revealed an increased signal intensity in 2/4 (50%). One of these nerves had an abnormal VEP and the other had a VEP latency at the upper limit of normal. The VEP was abnormal in 1/4 (25%). In the clinically affected optic nerves, the degree of loss of visual acuity was not associated with the longitudinal extent of the lesions shown by MRI. The mean length was 17.5 mm in optic nerves with a slight disturbance of visual acuity and 15.0 mm in nerves with severe visual loss.(ABSTRACT TRUNCATED AT 250 WORDS)