Magnetic resonance imaging of meningiomas

Twenty-eight patients with 32 meningiomas were studied on a 0.5-T superconductive magnetic resonance (MR) imager. This common, benign treatable tumor was more clearly seen on computed tomography (CT) than MRI in 53% of cases. This is a result of poor contrast between the tumor and the adjacent brain on all spin-echo and inversion-recovery pulse sequences. Those sequences that provide the greatest anatomic detail were best for identifying this low-contrast lesion. Inversion-recovery scans in particular demonstrated the tumor as a discrete hypointense mass (relative to nearby white matter) with excellent visualization of the dural base and white matter buckling indicative of extracerebral mass effect. Other characteristic features include: a hypointense rim because of the venous capsule (66%); mottling due to hypervascularity; a well defined edema collar that demarcates the tumor from adjacent brain; and hyperostosis with thickening of the calvaria and obliteration of its normal landmarks. MRI did not demonstrate tumor calcification but did demonstrate vascular encasement, displacement, and occlusion better than CT and as well as digital venous angiography.     

Magnetic resonance imaging of intracranial hemorrhage

The appearance and evolution of intracranial hemorrhage as detected by magnetic resonance (MR) imaging is complex. This article outlines the underlying physiology of hemorrhagic masses in order to explain their complex appearance. The MR appearance of intraparenchymal (benign and neoplastic) and extraparenchymal intracranial hemorrhage is described.     

Magnetic resonance imaging of intracranial venous angiomas

Magnetic resonance imagings (MRI) were made of intracranial venous angioma (six angiographically proved, four presumed). All draining veins were identified as a linear or a small round structure with a flow void. The stellate configuration was observed in seven of the ten patients. In two of the ten, the associated intraparenchymal hematoma was evident. Increased intensity of adjacent parenchyma on T2-weighted images was detected in four of ten patients, and a decreased intensity on the T1-weighted images was noted in three of eight. Thus, MRI is a pertinent diagnostic modality for evaluating intracranial venous angioma. Angiography does not seem to be required for confirmation in patients with typical MR findings.     

Magnetic resonance imaging of intracranial epidermoid tumours

Epidermoid tumours are rare lesions within the skull which are usually found in a cerebellopontine angle. In the computed tomography (CT) literature, they have been described as well-defined lesions of low density which seldom show calcification or tissue enhancement. We have recently encountered three intracranial epidermoids, which appeared to exhibit uniform findings on low field strength magnetic resonance (MR) of moderate signal intensity in the T1-weighted images and a bright signal (increased T2) in the T2-weighted sequences. It may be possible to predict accurately the presence of an epidermoid tumour when this particular configuration of findings is present.     

The value of magnetic resonance imaging in the diagnosis of intracranial meningiomas

Thirty-two patients suspected by Computed Tomography (CT) of having a meningioma were additionally imaged by Magnetic Resonance. Of these, seven patients had an eventual diagnosis other than meningioma. This represents a positive value of 76% for the diagnosis of meningioma by CT. Magnetic resonance imaging (MRI) improved positive predictive value to 86%. A diagnosis other than meningioma was made by MRI with greatest confidence when tumour signal intensity was either much greater or much less than that of grey matter. Comparison of Inversion Recovery (IR) and spin echo (SE) sequences showed IR to be superior for demonstration of supratentorial meningiomas. SE images were superior to IR in demonstrating calcification. MRI was of value in showing anatomical relationships, due to its multiplanar capacity and in demonstrating vessel patency. CT was generally superior in defining meningiomas and in demonstrating calcification.     

Magnetic resonance imaging of intracranial neoplasms at 0.02 tesla

Sixty-five patients with single or multiple intracranial neoplasms were examined with an MR imager operating at 0.02 tesla. In 56 patients the diagnosis was histologically confirmed. All patients had an abnormal CT finding. MR images were positive in 59 cases, while the lesion remained undetected or equivocal in 6 cases (2 pituitary adenomas and 4 meningiomas). The MR signal intensity of several meningiomas was equal to that of normal brain tissue. Some astrocytomas were better delineated on MRI than on CT. For the study of pituitary lesions, the spatial resolution was unsatisfactory. The ultralow field MR imager was found to be sensitive for the detection of other intracranial neoplasms.     

Atypical imaging appearances of intracranial meningiomas

Meningiomas are the commonest primary, non-glial intracranial tumours. The diagnosis is often correctly predicted from characteristic imaging appearances. This paper presents some examples of atypical imaging appearances that may cause diagnostic confusion.     

Magnetic resonance imaging of intracranial tumors in children and adolescents

Magnetic resonance (MR) scans were reviewed of 25 children and adolescents from the age of 9 months to 18 years referred with a suspected or proven diagnosis of intracranial tumor. Twenty-one of these children had MR scans positive for tumor. Histology was available in 14. The other seven patients were managed clinically as cases of cerebral tumor, although histologic confirmation was lacking. Seventeen tumors displayed an increase in both T1 and T2. One dermoid tumor and part of another displayed a very short T1 (less than that of white matter). Two hamartomas had T1s similar to that of gray matter and a small increase in T2. Four of the children did not show MR or computed tomographic (CT) evidence of intracranial tumors. Follow-up of these cases for 1-23 months after the MR and CT studies revealed no subsequent clinical evidence of tumor. MR scans showed more extensive abnormality than did third-generation CT scans in eight of 10 cases and more extensive abnormality than EMI CT 1010 scans in 10 of 11 cases. Mass effects were better demonstrated in 14 of the 16 patients in whom they were seen. CT demonstrated calcification better than did MR in all four cases in which it was identified. The tumor-edema interface was shown better on CT in each of the three cases with contrast enhancement on CT. MR is a sensitive method of evaluating intracranial tumors in children and adolescents.     

Magnetic resonance imaging of intracranial epidermoids: report of two cases

Intracranial epidermoids are uncommon benign tumors in the subarachnoid spaces. We have studied two patients with these tumors originating in the basal cisterns using magnetic resonance (MR) imaging, computed tomography (CT), and cerebral angiography. Both CT and MR showed the extraaxial position of these tumors and their extension into the posterior fossa well. Angiography did not show any abnormal vasculature but displacement of vessels by the tumor mass was well demonstrated. MR was found to be relatively specific in characterizing these tumors.     

颅内动脉粥样硬化的磁共振成像研究进展

颅内动脉粥样硬化(ICAD)与缺血性卒中关系密切,在我国已经成为脑卒中最重要病因之一。MRA作为诊断ICAD的影像手段目前已广泛应用于临床。高分辨力MRI可以提供血管壁结构和斑块成分等信息,目前ICAD的高分辨力MRI研究主要集中于评估斑块特征和明确病理机制等方面。就ICAD的MRI研究现状及发展趋势予以综述。     

Magnetic resonance of intracranial epidermoids.

The magnetic resonance images of seven patients with biopsy-proven epidermoids were evaluated. The epidermoids were hypointense on T1-weighted images. Intermediate density images revealed the tumors to be heterogeneous in signal intensity consisting of areas of hypo- and isointensity. Signal intensity on T2-weighted images was hyperintense and inhomogeneous in all but one case. CT performed in five patients demonstrated the tumors to be well-defined hypodense lesions without contrast enhancement.     

磁共振pH成像的研究

<正>1概述磁共振成像(MRI)技术的重要优势在于其无放射损伤及组织结构的高分辨力,可无创实时地检测组织结构及代谢物。众所周知,人体正常机能活动有赖于正常的细胞内外环境,包括正常的酸碱度     

Magnetic resonance imaging methodology

Introduction  

Magnetic resonance (MR) methods are non-invasive techniques to provide detailed, multi-parametric information on human anatomy, function and metabolism. Sensitivity, specificity, spatial and temporal resolution may, however, vary depending on hardware (e.g., field strength, gradient strength and speed) and software (optimised measurement protocols and parameters for the various techniques). Furthermore, multi-modality imaging may enhance specificity to better characterise complex disease patterns.     

磁共振pH成像的研究

1概述 磁共振成像（MRI）技术的重要优势在于其无放射损伤及组织结构的高分辨力,可无创实时地检测组织结构及代谢物。众所周知,人体正常机能活动有赖于正常的细胞内外环境,     

Magnetic resonance angiography of the intracranial vessels

In this overview the results and indications of Magnetic Resonance Angiography of the intracranial vasculature will be discussed. The value of MRA will be studied in the visualisation of normal variants of the cerebral anatomy, the imaging of cerebrovascular disease, the diagnosis of aneurysms and cerebral arteriovenous malformations, the preoperative setup of cerebral tumors and the demonstration of vascular compression.     

Magnetic resonance angiography of giant intracranial aneurysms

3D time-of-flight magnetic resonance angiography (3D TOF MRA) and 2D MRA with presaturation were evaluated in 18 patients with 21 giant intracranial aneurysms. 3D TOF MRA gave optimal images of proximal unruptured and nonthrombosed aneurysms. 2D MRA with presaturation was more informative in cases of distal, haemorrhagic or thrombosed aneurysms and in assessment of their components (thrombus, haemorrhage, patent residual lumen).     

Magnetic resonance imaging findings of intracranial papillary meningioma: a study on eight cases

ObjectivesTo increase the awareness on intracranial papillary meningiomas (PMs) by presenting magnetic resonance imaging (MRI) findings on this disease.Materials and methodsThe MRI findings and clinical presentations of nine discrete lesions in eight patients with pathologically documented PMs were retrospectively analyzed.ResultsMost tumors occurred in young adults. The tumors originated from the convexity meninges in five cases and from the parasagittal regions in four cases. The tumor shape was irregular in six cases, lobulated in two cases, and round in one case. By MRI, nine masses were primarily isointense (n=5) or mildly hypointense (n=4) to gray matter on T1-weighted images and inhomogeneous hyperintense (n=3) or isointense (n=6) to the cortex on T2-weighted and fluid-attenuated inversion recovery images. On diffusion-weighted imaging, the signal intensity of the tumor was increased in all lesions compared with the adjacent parenchyma. Tumor and brain interfaces were unclear in seven cases, cyst formation was observed in eight tumors, scattered hemorrhage was observed in three tumors, signal voids due to vessels were visible in four cases, and eight tumors had moderate or marked irregular peritumoral edema. Enhancement was homogeneous (n=2) or heterogeneous (n=7), an area of focal nodular enhancement was observed in three lesions, and the dural tail sign was visible in seven cases.ConclusionAlthough PM is rare, it should be considered in the differential diagnosis when evaluating intracranial neoplasms. Younger patient age, as well as imaging features such as unclear tumor–brain interface, internal heterogeneity including cyst formation, irregular enhancement, signal voids of vessels, and marked peritumoral edema can help distinguish PM from typical benign meningiomas.