MR imaging of CNS relapse of Whipple disease.

We report a case of late CNS relapse of Whipple disease without articular or digestive signs. Magnetic resonance (MR) imaging of the brain clearly showed the disappearance of the normal low intensity signal of the aqueduct of Sylvius and the presence of high intensity signals in the frontal white matter and in the caudate nucleus. This case suggests that MR imaging of the brain is the procedure of choice for identifying cerebral involvement in Whipple disease.     

Half-Fourier MR imaging of CNS disease

Three MR imaging techniques were compared in 37 CNS examinations. In each case, postprocessing of a single data set in three different ways was used for comparison. Eleven of the 37 patients had a clinical diagnosis of multiple sclerosis. The primary purpose of this investigation was to evaluate the quality of the half-Fourier imaging technique. With half-Fourier imaging, scan time can be reduced by approximately half without compromising spatial resolution. In T2-weighted examinations at 1.0 T (with present instrumentation), application of the half-Fourier technique leads to a decrease in lesion detectability in patients with multiple sclerosis: this is because there is a reduction in the signal difference-to-noise ratio of 32 +/- 11%. For T2-weighted screening of the CNS on high-field MR systems, with the exception of multiple sclerosis, half-Fourier imaging may offer a suitable compromise by decreasing scan time while preserving spatial resolution. Application of the half-Fourier method to T1-weighted techniques also results in diagnostic-quality images.     

Dynamic MR imaging: a further possibility for characterizing CNS lesions

To improve the specificity of MR imaging, 45 patients with different lesions in the CNS were studied with gadolinium-DTPA from June to December 1985. With a dosage of 0.2 ml/kg body weight, no adverse effects were seen. Seventeen of these patients were also studied with dynamic MR imaging, using a spin-echo sequence of TR = 100 msec and TE = 30 msec and a display matrix of 128(2). Four parameters were determined and compared with histologic findings: the time to peak of signal intensity, the ascent to peak of signal intensity, the height of peak of signal intensity, and the percentage of peak of signal intensity at the end of measurement. In this small series, arteriovenous malformations had a short time to peak and a steep ascent to peak as compared with tumors. Gliomas had a slow ascent to peak and usually a longer time to peak as compared with tumors of mesodermal origin. Paragliomas according to Zülch's classification had a steeper ascent to peak than gliomas. Dynamic MR with gadolinium-DTPA may lead to further information about lesions in the CNS, as the ascent to peak parameter seems helpful in discriminating among different lesions.     

MR imaging of CNS involvement in children affected by chronic liver disease

BACKGROUND AND PURPOSE: MR imaging sheds new light on CNS involvement in the course of acquired chronic liver disease; however, the exact pathogenetic mechanisms of hepatic encephalopathy and associated MR abnormalities remain unclear. Our purpose was to relate MR signal intensity abnormalities of the CNS to clinical, biochemical, and pathologic features of childhood-onset chronic liver disease. METHODS: Twenty-one patients (12 male and nine female patients) were included in the study; two had Crigler-Najjar disease type 2, 17 had chronic liver disease of different causes, and two had idiopathic copper toxicosis. Twelve patients had histologically proved liver cirrhosis, with a median disease duration of 175 months at the time of MR study. None had clinical symptoms of hepatic encephalopathy. MR imaging was performed using spin-echo T1- and T2-weighted sequences. RESULTS: Eleven patients had abnormal MR imaging findings of the brain revealed by T1-weighted MR sequences; two of the 11 had idiopathic copper toxicosis. The affected sites were the hypothalamus and globus pallidus, presenting symmetrical and bilateral high signal intensities, or the pituitary gland, which appeared homogeneously hyperintense, or both findings. Eight of the 12 patients with cirrhosis had abnormal MR signals of the brain. In these, the median cirrhosis duration was shorter (169 months) than in the remaining four patients with normal MR signals (177 months). A significant correlation was found between abnormal MR signals of the brain and cirrhosis (P = .008) and factor V activity (P = .008). CONCLUSION: MR imaging confirms the presence of abnormal brain signals in the globus pallidus, hypothalamus, and pituitary gland in patients with childhood-onset liver disease in the absence of clinical symptoms of encephalopathy. Signal intensity abnormalities are likely caused by an as yet unidentified metabolic process partially correlated with the severity of liver disease.     

MR imaging in a case of Hallervorden-Spatz disease

Magnetic resonance using a 0.5 T system and a T2-weighted spin-echo pulse sequence revealed symmetric areas of marked hypointensity of the globi pallidi in a case with a family history of and presenting with clinical features consistent with Hallervorden-Spatz disease. No such findings were seen in any of 16 normal volunteers of similar age. Magnetic resonance may be useful for diagnosing Hallervorden-Spatz disease.     

Lyme disease of the CNS: MR imaging findings in 14 cases

The MR images of 14 patients with clinical diagnoses of Lyme disease, CNS complaints, and positive Lyme titers were reviewed. MR examinations were abnormal in 43%. Areas of abnormal signal were identified within the cerebral white matter as well as within the brainstem.     

Structural changes of the substantia nigra in Parkinson's disease as revealed by MR imaging

BACKGROUND AND PURPOSE: The possibility of using MR imaging as a sensitive marker of the structural changes in Parkinson's disease has been a long-sought goal. We describe a new method for imaging and quantifying the morphologic changes of the substantia nigra in Parkinson's disease and compare radiologic findings with clinical evaluation. METHODS: Using a combination of two MR imaging inversion-recovery pulse sequences, the substantia nigra was imaged in six patients with Parkinson's disease and six age-related control participants. A radiologic index was defined and used to quantify the signal changes that were observed in the patients. The radiologic index was compared with clinical scores obtained from the Unified Parkinson's Disease Rating Scale. RESULTS: The images showed loss of signal in a lateral-to-medial gradient in cases of Parkinson's disease, corresponding to the known neuropathologic pattern of degeneration. The radiologic index was highly correlated with the Unified Parkinson's Disease Rating Scale score, and there was no overlap in radiologic indices between the patient and the control groups (P < .00005). CONCLUSION: This study suggests that MR imaging is sensitive to structural changes in even the earliest cases of Parkinson's disease, thereby indicating the potential for detecting presymptomatic disease. Furthermore, a radiologic measure has been defined that correlates with the conventional clinical measure of disease severity. Therefore, MR imaging could prove to be a sensitive biological marker for objective staging of the disease.     

神经纤维瘤病中枢神经系统的MRI表现

目的 探讨神经纤维瘤病(NF)的中枢神经系统(CNS)MR表现。方法 回顾性分析10例神经纤维瘤病患的临床资料并对其中枢神经系统MR表现进行分析，所有病例均行常规MR平扫及增强扫描。结果 10例病例中，NF—1型6例，表现为脑内胶质瘤、椎管内神经纤维瘤，4例合并皮肤损害，其中一例有家族史，NF—2型4例，表现为双侧听神经瘤、多发脑膜瘤或神经纤维瘤，皮肤损害少见。所有病例中增强扫描均发现平扫未发现之病灶。结论 MR能很好显示病变的大小、形态及信号特点，对检出神经纤维瘤病中枢神经系统的损害方面有优势，增强扫描可帮助发现平扫未见病灶。     

MR imaging of a group I case of Hallervorden-Spatz disease

Magnetic resonance (MR) imaging of a case of Hallervorden-Spatz disease (HSD) using a 1.5 T system is described. The patient showed progressive spastic diplegia with equinovarus deformity of the feet, dystonic postural movements, dysarthria, dysphagia, mental deterioration, optic nerve atrophy, and peripheral neuropathy. These clinical features were compatible with HSD. Symmetrical, decreased signal intensity was seen on both proton density weighted and T2-weighted spin echo images in the globus pallidus as well as in the substantia nigra (Group I). This MR finding suggests an increased iron deposition in these subcortical nuclei, which is characteristic of HSD. The characteristic MR imaging, together with the relevant clinical features, was considered to be useful for establishing the diagnosis of HSD.     

Incidence of postangiographic abnormalities revealed by diffusion-weighted MR imaging

BACKGROUND AND PURPOSE: Occasionally we have observed anecdotal cases of asymptomatic hyperintensities on diffusion-weighted MR (DW-MR) examinations of the brain of patients who previously underwent routine cerebral angiography. These observations, as well as MR imaging and transcranial Doppler data in the literature suggesting a high rate of procedure-associated emboli, raise concern regarding the underdiagnosis of asymptomatic focal infarction associated with cerebral angiography. In order to determine whether asymptomatic diffusion abnormalities are frequently associated with procedures, we prospectively obtained DW-MR images before and after routine cerebral angiography. METHODS: Twenty consecutive patients, who met protocol criteria and received a routine three- or four-vessel diagnostic cerebral angiogram at our institution, were evaluated. Using a Bayesian estimate to establish an upper bound for the incidence of an event with zero occurrences in a study sample, the study group size was selected to exclude a 10% incidence of abnormalities revealed by DW-MR imaging of patients who underwent previous cerebral angiography. Two neuroradiologists evaluated imaging studies. RESULTS: Neither clinical signs nor abnormalities on DW-MR images were found, which suggested no infarction after angiography in our patient sample. Based on this data, an upper bound of 9% (95% confidence) is predicted for the appearance of abnormalities revealed by DW-MR imaging after cerebral angiography. CONCLUSION: Cerebral angiography is associated with an incidence of asymptomatic cerebral infarction of no more than 9%. It well may be substantially lower than this estimate; a more accurate evaluation of the true incidence would require a significantly larger study population. This test provides a convenient noninvasive means of assessing procedure-related cerebral infarction, such as that which occurs after carotid endarterectomy or vascular angioplasty and stenting.     

Focal liver lesions evaluated by MR imaging

Magnetic resonance signal intensity of focal liver lesions is the result of their histological and cytological features. Therefore, analysis of lesion signal intensity and enhancement patterns obtained with magnetic resonance imaging is essential for the differential diagnosis of focal liver lesions. In this article, we review the magnetic resonance imaging features of the most common focal liver lesions.     

A case of hemiplegic migraine in childhood: transient unilateral hyperperfusion revealed by perfusion MR imaging and MR angiography.

We report on an 8-year-old girl with a typical attack of hemiplegic migraine, in whom MR angiography and perfusion MR imaging revealed unilateral dilation of branches of both the middle and posterior cerebral arteries and hyperperfusion of the ipsilateral hemisphere, respectively. The findings resolved spontaneously after the attack. These imaging techniques should be indicated for patients with migraine attacks and may play a role in assessing the vascular events in migraine headache.     

Magnetization transfer MR imaging in CNS tuberculosis.

BACKGROUND AND PURPOSE: CNS tuberculosis may simulate other granulomas and meningitis on MR images. The purpose of this study was to improve the characterization of lesions in CNS tuberculosis and to assess the disease load using magnetization transfer (MT) imaging. METHODS: A total of 107 tuberculomas in seven patients with or without meningitis and 15 patients with tuberculosis meningitis alone were studied. Fifteen patients with cysticercus granulomas with T2 hypointensity, five patients each with viral and pyogenic meningitis, and two patients with cryptococcal meningitis were also studied. The MT ratios were calculated from tuberculomas, cysticercus granulomas, and thickened meninges in tuberculous, viral, pyogenic, and cryptococcal meningitis and were compared within each pathologic group and with the MT ratio of different regions of normal brain parenchyma. Detectability of lesions on T1-weighted MT spin-echo (SE) images was compared with that on conventional SE and postcontrast MT-SE images. RESULTS: Thickened meninges appeared hyperintense relative to surrounding brain parenchyma in the basal and supratentorial cisterns on precontrast MT-SE images in all 18 patients with tuberculosis meningitis. These meninges were not seen or were barely visible on conventional SE images, and enhanced on postcontrast MT-SE images. The MT ratio from the thickened meninges of tuberculous meningitis was significantly lower than that from the meninges in cryptococcal and pyogenic disease and significantly higher than the meninges in viral meningoencephalitis. The MT ratio from T2 visible and invisible tuberculomas appeared to be significantly lower than that of normal white matter. The MT ratio of T2 hypointense cysticercus granuloma was significantly higher than that of T2 hypointense tuberculoma. CONCLUSION: Precontrast MT-SE imaging helps to better assess the disease load in CNS tuberculosis by improving the detectability of the lesions. With the use of MT ratios, it may be possible to differentiate tuberculosis from similar-appearing infective lesions on MR images.     

Pharmacokinetic parameters in CNS Gd-DTPA enhanced MR imaging

Dynamic MR imaging can be used to study tissue perfusion and vascular permeability. In the present article a procedure for dynamic MR is presented, which (a) accurately resolves the fast kinetics of tissue response during and after intravenous infusion of the paramagnetic contrast medium Gd-DTPA and (b) yields a linear relationship between the measured MR signal and the Gd-DTPA concentration in the tissue. According to these features, the measured signal-time curves can be analyzed within the framework of pharmacokinetic modeling. Tissue response has been parameterized using a linear two-compartment open model, with only negligible effects of the peripheral compartment on the central compartment. The three model parameters were fitted to the signal-time data pixel by pixel, based on a set of 64 rapid SE images (SE 100/10 ms, image scan time 13 s, interscan intervals 11 s). This makes it possible to construct parameter images, whereby structures become visible that cannot be distinguished in conventional Gd-DTPA enhanced MR. As a clinical example, the approach is discussed in a case of glioblastoma.