Magnetic resonance imaging in small lesions of the central nervous system. Improvement by gadolinium-DTPA

T1 values and T2 values (CPGM-sequence) of neurinomas and meningiomas were determined, and showed values close to those of white and grey matter or, in regressive cystic neurinomas, near the cerebrospinal fluid (CSF). By this overlapping in relaxation times, as well as by crossover and boundary effects, small tumors may be obscured. The application of gadolinium-DTPA allows easier identification even of small lesions, by the high contrast achieved on the T1 weighted imaging sequences, which also avoids crossover and boundary effects with the adjacent parenchyma and CSF. This is demonstrated in intrameatal acoustic neurinomas, vascular tumors, small and en plaque growing meningiomas, and tumors of the spinal canal.     

Hybrid radiofrequency and cryoablation device: preliminary results in an animal model

PURPOSE: To determine whether the simultaneous application of combined bipolar radiofrequency (RF) ablation and cryoablation in a hybrid system produces larger ablation zones than RF or cryoablation alone. MATERIALS AND METHODS: Multiple 15-minute ablations were performed in ex vivo bovine liver (n = 167) with a hybrid applicator system with RF ablation alone (0.3-0.7 A), cryoablation alone (3,500 psi, two freeze/thaw cycles), and combined RF/cryoablation (0.4-0.7 A, 1,000-3,500 psi) with use of a novel applicator consisting of two 2.5-cm active bipolar RF poles located on the same 18-gauge needle separated by two embedded cryoablation nozzles. Resultant coagulation diameters were compared with use of analysis of variance for more than three groups or Student t tests for two groups. Confirmation of the optimal parameters of combination RF/cryoablation was performed by reassessing a range of argon pressure (1,000-3,500 psi) and RF current (0.4-0.7 A) in in vivo porcine liver (n = 36). Arrays of two to four RF/cryoablation applicators were also assessed in ex vivo (n = 54) and in vivo (n = 12) liver. RESULTS: In ex vivo liver, simultaneous RF/cryoablation (0.6 A, 3,000 psi) produced 3.6 cm +/- 0.4 of short-axis coagulation. This was significantly larger than that achieved with optimal RF alone or cryoablation alone (1.5 cm +/- 0.3 and 1.6 cm +/- 0.3, respectively; F = 95; P < .01). The coagulation diameter with simultaneous combination RF/cryoablation was related in parabolic fashion to argon pressure and current with a multivariate r(2) of 0.68. For in vivo liver, optimal combination RF/cryoablation achieved 3.3 cm +/- 0.2 of coagulation, which was significantly larger than that achieved with RF alone (1.1 cm +/- 0.1; P < .01) or cryoablation alone (1.1 cm +/- 0.1 and 1.3 cm +/- 0.1; F = 203; P < .01). The greatest contiguous coagulation was achieved with multiple-applicator arrays. For ex vivo liver, short-axis coagulation measured 5.3 cm +/- 0.1, 6.4 cm +/- 0.1, and 7.6 cm +/- 0.1 for two-, three-, and four-applicator arrays, respectively. For in vivo liver, two-, three-, and four-applicator arrays produced 5.1 cm +/- 0.2, 5.8 cm +/- 0.5, and 7.0 cm +/- 0.5 of confluent coagulation, respectively. CONCLUSION: Simultaneous combination RF and cryoablation with use of a novel applicator design yielded significantly larger zones of coagulation than either modality alone. The large ablation diameters achieved warrant further investigation of the device.     

MR扩散峰度成像原理及其在中枢神经系统的初步应用

通过对水分子扩散运动的测量,扩散张量成像（ＤＴＩ）可以无创地对组织结构进行评价,而扩散峰度成像（ＤＫＩ）是以DTI为基础,对生物组织内水分子扩散的非高斯分布特征进行定量分析,揭示组织结构细微改变。DKI较DTI能提供更多关于组织微观结构的信息。综述DKI的原理及其在中枢神经系统的应用,包括神经退行性疾病、创伤性脑损伤、缺血性脑卒中、胶质瘤、多发性硬化、脑发育等。     

MR imaging of neoplastic central nervous system lesions: review and recommendations for current practice

MR imaging is the preferred technique for the diagnosis, treatment planning, and monitoring of patients with neoplastic CNS lesions. Conventional MR imaging, with gadolinium-based contrast enhancement, is increasingly combined with advanced, functional MR imaging techniques to offer morphologic, metabolic, and physiologic information. This article provides updated recommendations to neuroradiologists, neuro-oncologists, neurosurgeons, and radiation oncologists on the practical applications of MR imaging of neoplastic CNS lesions in adults, with particular focus on gliomas, based on a review of the clinical trial evidence and personal experiences shared at a recent international meeting of experts in neuroradiology, neuro-oncology, neurosurgery, and radio-oncology.     

Precise relaxation time measurements of normal-appearing white matter in inflammatory central nervous system disease

Precise relaxation time (RT) measurements have been made, with a standard deviation of 3% for T1 and T2 in white matter in normal volunteers. This sets an upper limit to the instrumental random errors (imprecision). Achieving this precision requires careful adjustment and use of the imager. The wide variation in RTs seen by other workers may be in part due to larger instrumental errors. We have measured RTs (both T1 and T2) in normal-appearing white matter in 16 normal controls and patients with multiple sclerosis (MS, 18), systemic lupus erythematosis (SLE, 16) and cerebral sarcoidosis (8). Both RTs were significantly higher in MS than in other patient groups and controls (P less than .05), possibly caused by microscopic lesions. T2 was elevated in SLE patients relative to controls and sarcoidosis patients (P less than .05), possibly because of microhemorrhages. Lesion RTs were abnormal but more variable and no significant differences between diseases were found.     

Pancreatic cystic lesions: discrimination accuracy based on clinical data and high resolution CT features

OBJECTIVE: To determine the accuracy of high-resolution computed tomography in discriminating among pancreatic cystic lesions with and without clinical history. METHODS: Multiphasic high-resolution computed tomographic scans of 100 proven cystic pancreatic lesions were retrospectively reviewed by 2 blinded imagers. Before and after a history of pancreatitis was revealed, readers classified lesions as either nontumor-related or tumor-related. Reviewers also classified lesions as benign or malignant and finally categorized each lesion as serous, mucinous, or other lesion. Diagnostic performance parameters for classification were calculated for each reader with and without history. RESULTS: Sixty-two lesions were tumor-related and 38 were not. Accuracy for classifying tumor-related from unrelated cysts for both reviewers increased (83%-92%, 85%-91%) when unblinded to pancreatitis history. Specificity also significantly increased (66%-88% and 84%) for both reviewers. CONCLUSIONS: Pancreatic-phase computed tomography enabled more than 80% accuracy in discriminating between tumor-related and unrelated lesions and increased with information of pancreatitis history.     

Invasive central nervous system aspergillosis in bone marrow transplantation recipients: an overview

Invasive central nervous system aspergillosis is being seen with an increased frequency, particularly due to the increased number of immunosuppressed patients. The major cause of invasive central nervous system aspergillosis is bone marrow transplantation. In most cases, aspergillosis develops in the paranasal sinuses and in the lungs, and secondarily spreads to the brain. Imaging of cerebral aspergillosis may present different patterns depending on the lesion's age and the immunologic status of the patient. Lesions of the spinal cord are far less common but has been encountered in our series. In this article we review the clinical and radiologic features of aspergillosis affecting the central nervous system in patients who underwent bone marrow transplantation. Different CT and MR patterns are presented, including pertinent clinical and pathologic material. Significant morbidity and mortality can be associated with this fungal infection, and it is therefore incumbent upon the radiologist to identify intracranial aspergillosis as early as possible so that appropriate therapy can be administered. Electronic Publication     

Brainstem involvement with mycosis fungoides: an unusual central nervous system complication

Changes in the brainstem were demonstrated with MR imaging in a patient with mycosis fungoides. Previous reports of CNS involvement in this rare disease have not had similar findings.     

Immunoscintigraphic imaging of inflammatory lesions: preliminary findings and future possibilities

Mixed leukocytes separated in vivo from patients' blood and labeled with lipophilic chelates of 111In and 99mTc are now used clinically for imaging inflammatory foci in many medical centers worldwide. Recent immunological advances have prompted investigations about using radiolabeled antibodies potentially specific for human neutrophils, labeling of these blood cells in vivo, and imaging inflammatory processes in patients. Early results are encouraging, allowing abscesses to be imaged with high specificity and presenting only minimal (10% to 20%) adverse immunogenic responses. However, problems remain, including low immunospecificity and lengthy procedures for radiolabeling of antibodies. These areas are currently subjects to further research that in time will contribute to make this modality convenient, simple, and efficacious.     

Unusual presentation of central nervous system cryptococcal infection in an immunocompetent patient

The imaging findings of cryptococcosis affecting the brain in immunocompetent patients can be different from the more commonly described findings in immunocompromised patients. We report a case of an extremely unusual MR appearance of central nervous system cryptococcosis in a 49-year-old immunocompetent man.     

磁化传递成像观察多发性硬化大鼠中枢神经系统病灶

目的：探索应用3.0T临床型MR设备进行磁化传递成像（MTI）观察多发性硬化（MS）大鼠中枢神经系统病灶的可行性。方法：用髓鞘少突胶质细胞糖蛋白多肽35-55（MOG35-55）致敏Lewis大鼠制备MS动物模型实验性自身免疫性脑脊髓炎（EAE）大鼠10只,正常对照组大鼠4只。3.0T临床型MR扫描仪配备小正交腕关节线圈,分别对大鼠脑和脊髓行T2W、T1磁化传递和T1非磁化传递三维容积扫描。利用工作站专业软件获得磁化传递率（MTR）图像。结果：成功建立MOG35-55-EAE模型大鼠10只。大鼠脑和脊髓的MTR图像具有较高的空间分辨率和对比度。MOG35-55-EAE病灶在T2WI上呈高信号,在MTR图像上表现为MTR值下降,呈低信号,在T1WI上呈低信号或者等信号。MTR图像对MOG35-55-EAE病灶检出率高,病灶显示清晰。对照组大鼠MR扫描未见异常。结论：应用3.0T临床型MR设备可以获得高质量的MOG35-55-EAE大鼠脑和脊髓MTR图像。MTI有望成为小动物中枢神经系统脱髓鞘疾病实验研究的体外监测手段。     

Reliability of gallium brain scanning in the detection and differentiation of central nervous system lesions.

Both 99mTc-pertechnetate and 67Ga-citrate brain scans were performed in 93 patients with cerebral neoplasms and in 70 others with cerebral infarction or hemorrhage. Tumor detection was clearly better with 67Ga(96%) than with 99mTc(85%). Cerebral infarctions consistently either failed to concentrate 67Ga(67%) of revealed a much lower concentration than the 99mTc study (27%). In 6% of the infarction patients, gallium and technetium scans were equivalent.     

MRI of central nervous system: early clinical results

In patients with central nervous system problems, a comparison of the results obtained with high-field MRI (1.5 T) to those achieved with more conventional imaging studies, primarily CT, reveals significant improvement in the demonstration of various abnormalities by MRI (56.5%), with increased specificity in some (29.5%). High-field MRI provides advantages over CT by providing both multiplanar images and superior contrast resolution. The diagnostic specificity of MRI is increased when acute, subacute, and chronic hematomas are visualized and when flowing blood within vessels is demonstrated in addition to the location and extent of the disease process. In this series, MRI produced a more accurate diagnosis in 8.7% of cases, revealed clinically unexpected abnormalities in 3.9% of cases, and was less invasive or avoided the risk of complications in 17.4% of cases. Despite the success of MRI, CT continues to play an important role in demonstrating calcification and contrast enhancement, and in evaluating patients in whom MRI is contraindicated or impossible because of an unsuitable clinical state.     

Paracoccidioidomycosis of the central nervous system: CT findings

A retrospective analisis of six cases of central nervous system paracoccidioidomycosis, all but one proven by biopsy and surgery, was carried out to study the CT and clinical data and pathological correlation. Most of the patients were from the country. Headache, vomiting, seizures and hemiparesis were the most frequent symptoms. Papilloedema was present in four patients with raised intracranial pressure. Five patients had chronic lung disease and two with advanced systemic disease, skin and mucous membrane lesions were also observed. The neurological disturbance was sometimes the presenting features and the diagnosis was discovered incidentally after surgery. Both solitary and multiple parenchymal lesions were observed and the cerebral hemispheres were more commonly involved in four patients. Local meningeal involvement was observed in one with a single cortical granuloma. We enphasise the usefulness of CT, showing a rounded or lobulated mass with an isodense or radiolucent centre after contrast enhancement, surrounded by an irregular wall of varying thickness. There was always moderate oedema, extending peripherally. Other infections or neoplastic diseases may present similar findings. Preoperative diagnosis should rest on integration of clinical data, chest films, laboratory and neuroimaging studies.     

Fetal MRI of the central nervous system: State-of-the-art

Prenatal ultrasonographic (US) examination is considered as the first tool in the assessment of fetal abnormalities. However, several large-scale studies point out that some malformations, in particular central nervous system (CNS) anomalies, are not well characterized through US. Therefore, the actual malformation severity is not always related to prenatal ultrasound (US) findings.Over the past 20 years, ultrafast Magnetic Resonance Imaging (MRI) has progressively increased as a prenatal 3rd level diagnostic technique with a good sensitivity, particularly for the study of fetal CNS malformations. In fact, CNS anomalies are the most common clinical indications for fetal MRI, representing about 80% of the total examinations.This review covers the recent literature on fetal brain MRI, with emphasis on techniques, safety and indications.     

High spectral and spatial resolution MRI of breast lesions: preliminary clinical experience

OBJECTIVE: In previous research, high spectral and spatial resolution (HiSS) echo-planar spectroscopic imaging (EPSI) was successfully applied to the human breast, obtaining improved contrast, anatomic detail, and sensitivity to contrast agents. To test HiSS in the clinical setting, we used HiSS MRI to image 30 women with suspicious breast lesions. SUBJECTS AND METHODS: Women with suspicious breast lesions were scanned before and after contrast administration using EPSI at 1.5 T (0.63-mm in-plane resolution, 2.6-Hz spectral resolution). Images with intensity proportional to the water signal peak height in each voxel were synthesized and compared with standard clinical fat-saturated and early dynamic subtraction images. Pre- and postcontrast HiSS images were compared to assess the effect of the contrast agent on water resonance structure. RESULTS: HiSS images scored significantly better than standard clinical images in lesion conspicuity, margin definition, and internal definition, even though they were acquired before contrast agent injection. Fat suppression was more complete and uniform and detail was shown on HiSS images more clearly than on conventional fat-saturation images. Thus, HiSS images often allowed easier evaluation of the lesion. Contrast agent-affected changes were often spatially and spectrally inhomogeneous. CONCLUSION: HiSS scans were successfully integrated into standard clinical examinations and provided diagnostically useful images before contrast agent injection. Thus, it might be possible to characterize suspicious lesions on the basis of precontrast high-resolution spectral information. This information and information about the effect of contrast agents could potentially improve the specificity of breast MRI.