Cerebral NMR: diagnostic evaluation of brain tumors by partial saturation technique with resistive NMR

Summary One hundred and forty patients with cerebral neoplasms were examined in a 0.12-Tesla prototype resistive NMR proton imaging device by partial saturation technique. NMR was superior to CT in tumor and edema localization and equal to CT in tumor and edema detection. NMR, however, was not able to clearly separate tumor from edema, a separation that contrast enhanced CT achieved.     

颅内血管外皮细胞瘤的MRI及CT诊断

目的:探讨颅内血管外皮细胞瘤的MRI及CT影像学特点,以提高诊断水平。材料和方法:回顾性分析经手术病理证实的颅内血管外皮细胞瘤4例。4例均行MRI扫描,其中2例并行CT扫描。结果:4例血管外皮细胞瘤分别位于前、中颅窝、右侧桥小脑角区及右顶部各1例,均呈明显分叶状。T1WI示肿瘤呈高或等、低混杂信号,T2WI示肿瘤呈等或等、高混杂信号。增强扫描示肿瘤实性部分高度增强,其中4例肿瘤周边均可见不同程度水肿带,3例见流空血管影,1例肿块内见坏死囊变灶、1例邻近颅骨骨质破坏,1例见幕上轻度脑积水。CT平扫示肿瘤呈高密度,未见瘤内钙化、邻近颅骨骨质增生及脑膜尾征等脑膜瘤常见征象。结论:MRI及CT表现对颅内血管外皮细胞瘤的诊断有一定的作用,最终诊断依靠病理。     

MRI (NMR) in the diagnosis of brain-stem tumors

Summary Patients with a brain-stem tumor were studied with NMR. The full extent of the lesion as well as its relationship with the adjacent structures was clearly demonstrated in all cases. Although NMR is, in many aspects, superior to CT and angiography, these examinations remain useful complementary methods.     

PET/MRI: Multiparametric imaging of brain tumors

A combination of morphological imaging of the brain with microstructural and functional imaging provides a comprehensive overview of the properties of individual tissues. While diffusion weighted imaging provides information about tissue cellularity, spectroscopic imaging allows us to evaluate the integrity of neurons and possible anaerobic glycolysis during tumor hypoxia, in addition to the presence of accelerated synthesis or degradation of cellular membranes; on the other hand, PET metabolic imaging is used to evaluate major metabolic pathways, determining the overall extent of the tumor (¹⁸F-FET, ¹⁸F-FDOPA, ¹⁸F-FCH) or the degree of differentiation (¹⁸F-FDG, ¹⁸F-FLT, ¹⁸F-FDOPA and ¹⁸F-FET). Multi-parameter analysis of tissue characteristics and determination of the phenotype of the tumor tissue is a natural advantage of PET/MRI scanning. The disadvantages are higher cost and limited availability in all centers with neuro-oncology surgery. PET/MRI scanning of brain tumors is one of the most promising indications since the earliest experiments with integrated PET/MRI imaging systems, and along with hybrid imaging of neurodegenerative diseases, represent a new direction in the development of neuroradiology on the path towards comprehensive imaging at the molecular level.     

CT and MR imaging in atypical teratoid/rhabdoid tumors of the central nervous system

Introduction Atypical teratoid/rhabdoid tumors (ATRT) are rare aggressive neoplasms of the CNS affecting predominantly very young children. Methods We retrospectively reviewed the imaging findings of 9 CT and 32 MR examinations of the brain and spine of 33 children. Results Of the 33 tumors, 11 were located in the infratentorial compartment, 16 in the supratentorial compartment, 5 in both cranial compartments, and 1 in the lower thoracic spinal cord. The mean age of the children with infratentorial or infra- and supratentorial tumors was significantly lower than the mean age of the children with purely supratentorial tumors. Heterogeneity on imaging, large size and high tumor stages are striking features reflecting the aggressive nature of this histopathological entity. Although not present in the majority of children, a distinct and unusual pattern of a wavy band-like enhancement surrounding a central hypointensity was present in 12 of 32 children (38%) in whom contrast medium was used. Conclusion To the best of our knowledge this is the largest number of imaging examinations of ATRTs so far reported. A rather unusual pattern of contrast enhancement may be typical of ATRTs. This work was funded by the German Children’s Cancer Foundation (Deutsche Kinderkrebsstiftung).     

Anterior mediastinal tumors: diagnostic accuracy of CT and MRI

Purpose

To compare the diagnostic accuracy for anterior mediastinal tumors among CT, MRI, and both CT and MRI, and to determine the optimal CT and MRI procedures for the diagnosis of anterior mediastinal tumors.

Materials and methods

Both CT and MRI were performed in 127 patients with pathologically diagnosed anterior mediastinal tumors. The patients included 48 cases of thymoma, 12 cases of thymic carcinoma, 12 cases of thymic cyst, 20 cases of mature teratoma, 13 cases of malignant germ cell tumor, and 22 cases of malignant lymphoma. The CT and MRI scans were assessed by two chest radiologists without knowledge of their clinical and pathologic data. The observers recorded various CT and MRI findings and their first choice of diagnosis.

Results

The two observers made a correct first-choice diagnosis in an average of 78 (61%) of 127 cases on CT, 71 (56%) of 127 cases on MRI, and 85.5 (67%) of 127 cases on both CT and MRI. These included 83% cases of thymoma on CT, 84% on MRI, and 85% on both CT and MRI; 38% cases of thymic carcinoma on CT and 13% on MRI, and 33% on both CT and MRI; 46% cases of thymic cyst on CT and 71% on MRI, and 63% on both CT and MRI; 58% cases of mature teratoma and 38% on MRI, and 78% on both CT and MRI; 35% cases of malignant germ cell tumor on CT and 27% on MRI, and 31% on both CT and MRI; and 55% cases of malignant lymphoma on CT and 43% on MRI, and 61% on both CT and MRI. There were significant differences between the diagnostic accuracy by CT and MRI in the cases with both thymic cysts and thymic carcinoma (p < 0.05).

Conclusion

CT is equal or superior to MRI in the diagnosis of anterior mediastinal tumors except for thymic cyst. CT should be considered the modality of choice following chest radiography, however, in certain circumstances, such as thymic cyst with hemorrhage or inflammation which mimic solid tumor despite low enhancement, MRI may be better in distinguishing anterior mediastinal tumors. For more helpful information in the diagnosis of mature teratoma after CT, MRI may follow.     

Cross-sectional imaging with CT and/or MRI of pediatric chest tumors

The purpose of this study was to provide an overview of the spectrum of pediatric chest masses, to present the results of cross-sectional imaging with CT and/or MRI, and to define diagnostic criteria to limit differential diagnosis. Seventy-eight children with thoracic mass lesions were retrospectively evaluated using CT (72 patients) and/or MR imaging (12 patients). All masses were evaluated for tissue characteristics (attenuation values or signal intensity, enhancement, and calcification) and were differentiated according to age, gender, location, and etiology. Twenty-eight of 38 (74 %) mediastinal masses were malignant (neuroblastoma, malignant lymphoma). Thirty of 38 (79 %) pulmonary masses were metastatic in origin, all with an already known primary tumor (osteosarcoma, Wilms tumor). With one exception, all remaining pulmonary lesions were benign. Seventeen of 21 (81 %) chest wall lesions were malignant (Ewing sarcoma, primitive neuroectodermal tumor). The majority of mediastinal and chest wall tumors in children is malignant. Lung lesions are usually benign, unless a known extrapulmonary tumor suggests pulmonary metastases. Cross-sectional imaging with CT and/or MRI allows narrowing of the differential diagnosis of pediatric chest masses substantially by defining the origin and tissue characteristics. Magnetic resonance imaging is preferred for posterior mediastinal lesions, whereas CT should be used for pulmonary lesions. For the residual locations both modalities are complementary. Received 7 March 1997; Revision received 9 September 1997; Accepted 14 November 1997     

NMR imaging of congenital intracranial germinal layer neoplasms

Summary NMR images in five patients with surgically proved, congenital germinal layer intracranial neoplasms (two dermoid and three epidermoid tumors) were reviewed. The dermoids were typically midline (suprasellar or parapineal) masses with sharply-defined margins. Relaxation times were variable, but if fat was present, T₁ was decreased, and T₂ was increased. The epidermoids were off the midline (cerebellopontine angle, temporal lobe, frontal lobe) masses with generally long T₁ and T₂ relaxation times. Obstructive hydrocephaly was noted in one patient, and tumor to ventricular communication was demonstrated in another.     

Gastrointestinal stromal tumors: CT and MRI findings

The objective of this study was to report the CT and MRI appearances of primary and metastatic gastrointestinal stromal tumor (GIST). The clinical and imaging findings of 31 patients with histological and immunohistochemical diagnosis of GIST were reviewed. The CT and MRI findings were assessed independently for size, location, enhancement characteristics, and pattern of metastatic disease. The tumors were of enteric (n=13), gastric (n=12), duodenal (n=2), and rectal (n=3) origin. In one case the primary site was the mesentery, without involvement of bowel. Primary tumors were typically exophytic (79%), larger than 5 cm (84%), and inhomogeneously enhancing (84%). Central necrosis of all tumors (37%) and aneurysmal dilation of enteric tumors (33%) were less common. Metastases were most commonly to mesentery (26%) or liver (32%). Less common findings were ascites (7%) and omental caking (3%). Liver metastases were hypervascular in 92% of patients and rapidly became cystic following therapy with imatinib mesylate (Gleevec; Novartis, East Hanover, NJ, USA). Lung metastases, bowel obstruction, vascular invasion, and significant lymphadenopathy were not seen in any patient. GISTs have some specific CT findings which could help differentiate them from other gastrointestinal tumors. Liver metastases became cystic following therapy, mimicking simple cysts. MRI was better than single-phase CT for assessing liver metastases, while CT was more sensitive for mesenteric metastases.     

CT与MRI时代X线平片在骨肿瘤诊断中的作用

在科技快速发展的今天，CT和MRI等成像技术发展很快，在影像诊断中起到重要作用，而忽略了常规X光平片的作用。由于骨关节结构和X光平片的特点，X光平片在骨肿瘤的诊断中有非常重要的作用。根据我们大量的临床经验，下面就X光平片、CT和MRI检查方法各自的优势和缺点及在骨肿瘤诊断中的作用作一介绍。     

Intracranial meningiomas: How frequent are indicative findings in CT and MRI?

Summary Frequencies of CT and MRI findings characteristic of meningiomas were compared in 50 cases. Plain and contrast enhanced examinations with CT and MRI were evaluated retrospectively regarding 12 criteria known to be indicative of the diagnosis of meningiomas. CT proved to be superior in demonstrating calcifications and a typical tumor density. On the other hand, MRI was better suited for identifying the extraaxial location of tumors, the broad contact of tumors to the meninges, tumor capsules and meningeal contrast enhancement adjacent to the tumor. Both methods provided nearly equal results in demonstrating mass effects, hyperostoses, intensive and homogeneous contrast enhancement, and smooth tumor contours after contrast administration. On the whole, neither of the two methods demonstrated a universal superiority for the diagnosis of intracranial meningiomas. Rather, each method displayed distinct advantages.     

CT和MRI三维定位在神经导航立体定向系统中的应用

目的：为神经导航定位系统提供最精确的医学影像资料，提高神经外科手术的质量和成功率。材料和方法：结合医学影像的薄层扫描和三维重建技术，调整CT和MRI导航定位扫描中的各项参数。结果：确定了神经导航立体定向系统的CT和MRI定位扫描步骤及参数，为临床提供了精确的影像资料，共完成25例病例的手术治疗，效果满意。结论：精确的医学影像资料是神经导航定位系统准确性的重要保证。     

脑肿瘤诊断中CT和MRI造影剂的应用和进展

目的：在脑肿瘤诊断中，除常规ＣＴ和ＭＲＩ外，造影剂的广泛应用逐渐引起人们的重视。动态ＣＴ和ＣＴ血管造影的引入，改善了对肿瘤血供的认识。而动态ＭＲＩ、磁化传递对比、大剂量增强ＭＲＩ、ＭＲ血管造影、脂肪抑制和灌注ＭＲＩ的应用，对术前估价脑肿瘤特征意义重大。     

颅内神经元及混合性神经元-神经胶质肿瘤的MRI诊断

目的:探讨颅内神经元及混合性神经元-神经胶质肿瘤的MRI表现特征,以提高对其认识和诊断水平。方法:复习22例经手术病理证实的神经元及混合性神经元-神经胶质肿瘤的临床和影像资料,结合文献分析其MRI表现特征。结果:5例中枢神经细胞瘤均位于侧脑室内,呈不均匀长T1、长T2信号和不均匀强化;1例神经节细胞瘤位于颞叶,呈长T1、长T2信号,无瘤周水肿和强化;12例神经节细胞胶质瘤中,6例在颞叶,5例为囊性并有强化壁结节;2例胚胎发育不良性神经上皮肿瘤均位于颞叶皮质,呈不均匀长T1、长T2信号,无瘤周水肿和强化;1例婴儿促纤维增生性神经节细胞胶质瘤位于颞叶皮质,为不均匀长T1和一致性长T2信号,无瘤周水肿,呈环状强化;1例乳头状胶质神经元肿瘤在颞叶,呈囊性并有不规则壁结节,其囊壁和壁结节发生强化。结论:MRI检查,不同类型的神经元及混合性神经元-神经胶质肿瘤各具其好发部位并多有一定表现特征,结合患者年龄和临床表现,常可做出倾向性诊断。     

Intradural spinal tumors: current classification and MRI features

The differential diagnosis of intradural spinal tumors is primarily based on location, but the clinical presentation, age, and gender of the patient are also important factors in determining the diagnosis. This comprehensive review focuses on the current classification, clinical symptoms, and MRI features of the more common intradural extramedullary and intramedullary neoplastic lesions. This review does not include extradural lesions.     

Morphological and functional imaging in COPD with CT and MRI: present and future

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality worldwide. COPD is defined by irreversible airflow obstruction. It is a heterogeneous disease affecting the airways (i.e. chronic bronchitis, airway collapse), the parenchyma (i.e. hyperinflation, air trapping and emphysematous destruction) as well as the vasculature (i.e. hypoxic vasoconstriction, rarefication and pulmonary arterial hypertension) with different severity during the course of the disease. These different aspects of COPD can be best addressed by imaging using a combination of morphological and functional techniques. Three-dimensional high-resolution computed tomography (3D-HRCT) is the technique of choice for morphological imaging of the lung parenchyma and airways. This morphological information is to be accomplished by functional information about perfusion, regional lung mechanics, and ventilation mainly provided by MRI. The comprehensive diagnostic possibilities of CT complemented by MRI will allow for a more sensitive detection, phenotype-driven characterization and dedicated therapy monitoring of COPD as presented in this review.     

CT and MR imaging findings of endocrine tumor of the pancreas according to WHO classification

The pancreatic endocrine tumors are rare neuroendocrine tumors of the pancreas originating from totipotential stem cells or differentiated mature endocrine cells within the exocrine gland. Endocrine tumors are usually classified into functioning and non-functioning tumors and presents with a range of benignity or malignancy. In this article, we present the various CT and MR imaging findings of endocrine tumors of pancreas according to recent WHO classification.     

Retinoblastoma: CT and MRI

To evaluate the effectiveness of CT and MRI at 0.5 T in the diagnosis and staging of retinoblastoma, we studied 11 patients in whom retinoblastoma was clinically suspected. Nine of the eleven had surgically proven retinoblastoma; in the other two a diagnosis of Coat's disease was made. MRI was not as specific as CT for diagnosing retinoblastoma, due to its lack of sensitivity in detecting calcification; it did, however, have superior contrast resolution. On MRI, Coats' discase was reliably diagnosed and easily differentiated from retinoblastoma. Moreover, the greater ability of MRI to differentiate subretinal fluid from tumour also confers high accuracy in measuring tumour size. CT is still the study of choice in the diagnosis of retinoblastoma, but when MRI is available, it should be performed for better differentiation from lesions such as Coats' disease.     

小脑幕脑膜瘤的CT、MRI诊断

目的:探讨小脑幕脑膜瘤的CT、MRI表现,提高其诊断水平。材料和方法:回顾性分析17例经病理证实为小脑幕脑膜瘤的CT、MRI表现。结果:17例小脑幕脑膜瘤中,肿瘤呈哑铃状8例、突向幕下6例和突向幕上3例。CT呈略高密度12例、等密度3例和完全钙化2例。T1WI呈等低信号8例和略高信号5例;T2WI略高信号11例和等信号2例。肿瘤非钙化部分均呈明显增强。结论:小脑幕脑膜瘤的CT、MRI表现较为典型,但单纯CT轴位扫描定位困难,CT多层面重建(MPR)及MRI多方位扫描有助于对其做出正确诊断。     

鼻咽腺样体肥大的MR及CT诊断

目的:探讨腺样体肥大的CT及MR诊断价值及腺样体-鼻咽腔比率(A/N比值)对判断腺样体肥大程度的应用。方法:分析139例腺样体肥大患者的CT及MR表现,其中作CT矢状面图像重组或MR矢状面扫描的42例。重点观察病变部位的形态改变、邻近解剖关系及其并发症,并对其矢状面图像进行A/N比值测定。结果:腺样体肥大的CT及MR表现为鼻咽顶后壁中央弥漫性的软组织增生,呈团块状、山丘样突出或不规则增厚,咽旁间隙及颈动脉鞘区均无浸润表现,邻近骨质无异常改变。腺样体肥大指数A/N比值≥0.71有33例,0.70≥A/N比值≥0.61有7例,A/N比值≤0.60有2例。结论:CT和MR的横断面图像及矢状面图像的A/N比值的测定能准确地诊断腺样体肥大,明确并发症,并能准确量化肥大程度。