T2*-weighted MRI in diagnosis of multiple system atrophy

Abstract Background Putaminal iron deposition is a histopathological feature of multiple system atrophy (MSA), which is not observed in patients with idiopathic Parkinson's disease (PD). T2*-weighted magnetic resonance imaging (MRI) gradient echo (GE) sequences are sensitive for paramagnetic susceptibility changes and therefore may support the clinical differential diagnosis between MSA and PD. Methods We evaluated putaminal signal intensities on 1.0 Tesla scans of 52 MSA patients, 88 patients with PD and 29 healthy control subjects. Results The typical finding in T2* GE sequences of MSA patients was a signal loss of the dorsolateral putamen, which showed a high specificity (>0.91), but was present in only a subpopulation of patients (sensitivity 0.64–0.69). The combination of the latter with additional presence of a hyperintense lateral rim in fluid attenuated inversion recovery (FLAIR) sequences increased the specificity to 0.97. Using a quantitative evaluation of putaminal signal intensities in defined regions of interest MSA and PD could be discriminated with a diagnostic accuracy (r) of up to 0.82. Conclusion Although the separation of groups remains incomplete, the use of T2*-weighted GE sequences combined with FLAIR may be helpful for the differential diagnosis of MSA versus PD considering its fast application, easy evaluation, broad availability, the specificity of findings and the presence of putaminal signal loss already at early disease stages.     

磁共振梯度回波T*2 成像诊断急性脑出血的意义

目的评价磁共振梯度回波T2成像(GRET2WI)诊断急性脑出血的意义。方法发病1～24h的21例急性脑出血患者在行CT检查后,行GRET2WI检查及常规MRI检查,比较其诊断价值。结果21例出血灶在GRET2WI均表现为边界清楚的极低信号,或表现为边界清楚的低信号环,内部为略高信号或低信号区内混杂小点、斑片状高信号,使脑出血病灶显示非常清楚。6例在基底节区,同侧或对侧丘脑发现有1～7个直径2～5mm的圆形、斑点状的极低信号,为GRET2WI检测出的脑微出血。结论应用GRET2WI技术可以早期准确地诊断脑出血,可以全面了解患者颅内损害情况。     

Usefulness of three-dimensional T1-weighted spoiled gradient-recalled echo and three-dimensional heavily T2-weighted images in preoperative evaluation of spinal dysraphism

Purpose

The aim of this study was to evaluate the usefulness of three-dimensional T1-weighted spoiled gradient-recalled echo (3D T1-GRE) images for the preoperative anatomical evaluation of lumbosacral lipoma, thick filum terminale, and myelomeningocele as a means of compensating for the drawbacks of 3D heavily T2-weighted (3D hT2-W) images.

Methods

Nine patients with lumbosacral lipomas, one patient with tight filum terminale, and five patients with myelomeningoceles were included in this study. 3D T1-GRE images were compared with 3D hT2-W images or conventional magnetic resonance images in terms of delineation of lipomas and other structures in the patients with lipomas and tight filum terminale. For patients with myelomeningoceles, 3D T1-GRE images were compared with 3D hT2-W images in terms of artifacts in the cerebrospinal fluid (CSF) space.

Results

The 3D T1-GRE images demonstrated lipomas with good contrast to the spinal cord and CSF space and more clearly delineated the anatomical relationship between lipomas and these structures than did the 3D hT2-W images. The 3D T1-GRE images delineated dural defects through which extradural lipomas penetrated into the intradural space. The 3D T1-GRE images also demonstrated the presence or absence of lipomas in the filum terminale and the absence of artifact in the myelomeningoceles. Furthermore, they were useful for differentiating artifacts observed on the 3D hT2-W images from nerve elements.

Conclusions

The complementary use of 3D T1-GRE and 3D hT2-W images may compensate for the drawbacks of 3D hT2-W images and may eventually improve lesion visualization and surgical decision making.     

T2*-weighted MRI differentiates multiple system atrophy from Parkinson's disease

To compare the ability of T2*-weighted gradient echo (GE) and T2-weighted fast spin echo images to distinguish between patients with idiopathic PD and multiple system atrophy (MSA), the authors studied 15 patients with probable MSA, 40 patients with PD, and 17 healthy control subjects. Hypointense putaminal signal changes were more often observed in MSA than in PD using T2* but not T2-weighted images, indicating that T2*-weighted GE sequences are of diagnostic value for patients with parkinsonism.     

Usefulness of T2* weighted magnetic resonance image in the diagnosis of head injury on chronic stage]

T2* weighted gradient echo image has heightened diagnostic sensitivity to hemorrhage, which is attributed to magnetic susceptibility-induced static field inhomogeneities arising from paramagnetic blood breakdown products such as hemosiderin, which shorten T2*. We examined 4 cases of head injury in chronic stage by T2* weighted images and assessed the clinical application of this sequence for diagnosis of the intracranial lesion. All patients underwent CT scan on acute stage and long-term follow up was performed. In all cases, abnormally low signals in the brain and subarachnoid space were more conspicuous with the T2* weighted image than with any of the conventional sequences. In 2 cases with diffuse axonal injury, of which lesions were not detected on acute stage CT scan, hypointensity area was clearly demonstrated in the cerebral peduncle and corpus callosum on T2* weighted images. Selection of T2* weighted image into the routine MR examination of patients with chronic stage of the head injury is recommended.     

Diagnosis of cerebral venous thrombosis with echo-planar T2*-weighted magnetic resonance imaging

BACKGROUND: Magnetic resonance (MR) signal changes suggestive of cerebral venous thrombosis (CVT) on T1- and T2-weighted images may be subtle and their identification requires a high degree of suspicion. Magnetic resonance venography remains essential for definitive diagnosis. Recent reports have shown that T2(*)-weighted MR sequence is more sensitive than T1-weighted, T2-weighted, and fluid-attenuated inversion recovery (FLAIR) images in detecting subarachnoid and intracerebral hemorrhages, both of which can be seen in association with CVT. The value of T2*-weighted magnetic resonance imaging (MRI) in diagnosing CVT has not been well studied. OBJECTIVES: To investigate and describe T2*(susceptibility-weighted) MRI findings in 5 patients with CVT. METHODS: We reviewed our stroke database from May 1, 1997, through May 31, 2001. The diagnosis of CVT was made in 6 patients, 5 had an MRI with T2* sequence. We examined T2*/susceptibility-weighted images for these 5 patients to determine their ability, relative to T1-weighted, T2-weighted, and FLAIR sequences, to detect CVT. RESULTS: On T2*-weighted images, we were able to detect areas of hypointensities in the affected veins and/or sinuses in all 5 patients. Thrombosed veins and/or sinuses were more easily seen on T2*-weighted images than on any other MR sequence. The T2* sequence also allowed visualization of associated hemorrhagic venous infarcts, which were considerably less obvious on other MR sequences. CONCLUSIONS: The T2*-weighted MR sequence can be useful in rapid detection of CVT and may enable the diagnosis to be made prior to MR venography. This is particularly important in clinically unsuspected patients, in whom MR venography is rarely obtained.     

磁共振梯度回波T2*加权成像诊断家族性多发性脑海绵状血管畸形的价值

目的 探讨磁共振梯度回波T2*加权成像(GRE T2*-WI)诊断家族性多发性脑海绵状血管畸形(FCCM)的价值.方法 对FCCM患者的2个家系26名成员进行颅脑CT、常规MRI(T1WI、T2WI、T2FLAIR、DWI及SE)及GRE T2*-WI检查.结果 GRE T2*-WI检查发现FCCM患者12例,均为多发病灶,平均检出病灶23个,病灶主要位于基底节区,其次为皮质-皮质下、丘脑、小脑和脑干.病灶呈特异的高低混杂信号,周边围有一圈黑色低信号环,极具特征性.常规MRI检出脑内病灶数目(平均病灶数5～17个)、疑诊或确诊为FCCM患者的例数(平均例数3～9例),由多至少依次为SE、DWI、T2FLAIR、T1WI和T2WI,均较GRE T2*-WI少.而颅脑CT仅对病灶较大、合并有钙化或出血的3例患者疑诊为脑海绵状血管畸形.结论与CT和常规MRI相比,GRE T2*-WI可以更清楚地显示脑海绵状血管畸形病灶,为诊断提供更可靠的依据.     

Significance of the T2*-weighted gradient echo brain imaging in patients with infective endocarditis

Background

Although aneurysm formation accompanying parenchymal hemorrhage is one of devastating complications in the central nerves system (CNS), imaging studies of the brain are not routinely warranted in patients with infective endocarditis (IE). To assess the clinical importance for detecting silent lesions in the central nervous system, we investigated hypointense signal spots detected on the brain T2*-weighted MR imaging in patients with IE.

Methods and results

Eleven patients with IE were retrospectively reviewed. Seven patients (63.6%) showed hypointense signal spots on T2*-weighted MR images. The number of hypointense signal spots increased within only a few weeks in five patients.

Conclusion

The brain T2*-weighted MR imaging in patients with IE may have a potential role to detect CNS lesions with clinical significance of potentially high risk of intracranial hemorrhage. T2*-weighted hypointense signal spots may be specific to brain involvement, and be quite useful in monitoring CNS lesions associated with IE, even if they are asymptomatic.