肛周脓肿的磁共振成像研究

目的探讨磁共振成像（MRI）对肛周脓肿的诊断价值。方法回顾性分析2007年7月至2009年3月间复旦大学附属金山医院收治的50例肛周脓肿患者的临床和MRI影像学资料。按以下步骤进行MRI检查：横断面T1WI,横断面、冠状面和（或）矢状面T2WI抑脂序列平扫,横断面、冠状面和（或）矢状面增强扫描。分析脓肿的部位、大小、形态、信号和增强特征。结果50例患者通过MRI共检出51个脓肿病灶．脓肿在T1WI表现为等或略低信号,T2WI抑脂脓腔呈明显高信号。增强见脓肿壁明显强化。脓肿最大径（3．4±1．7）cm,脓腔最大径（2．7±1．7）cm。脓肿呈类圆形26个,长圆形18个,新月形7个：脓腔单房41个,多房10个。脓肿位于肛提肌下方、括约肌间沟上方23例．位于括约肌间沟下方3例．跨肛提肌及括约肌间沟1例,跨肛提肌7例,跨括约肌间沟16例,肛提肌上方1例。结论MRI能无创、方便、准确地诊断肛周脓肿,清晰显示脓肿与肛管结构的解剖关系。     

Magnetic resonance imaging of acute subarachnoid hemorrhage

The feasibility, safety, and diagnostic value of magnetic resonance (MR) imaging versus computerized tomography (CT) scanning were compared in 30 patients with clinical evidence of subarachnoid hemorrhage. Subarachnoid blood was identified more often and more information was available about the site and source of the hemorrhage on MR imaging than on CT. Magnetic resonance imaging could be used safely both before and after the operation, provided that nonferromagnetic clips were used and that comprehensive monitoring and cardiorespiratory support were available. Postoperative studies showed that artifacts from metallic implants and from patient movement caused less image degradation on MR images than on CT scans.     

Magnetic resonance imaging of brain contusion

In this study we investigated the time course of brain contusions using magnetic resonance imaging and compared the findings with those of a computed tomography scan. The lesions, which were demonstrated as homogeneous density areas on the computed tomography scan were demonstrated as different intensity areas in the magnetic resonance image. The intensity of the images varied according to the time at which the images were obtained. The findings indicated changes in the nature of the contusions including hematoma hemoglobin, perifocal edema extension, and so on. In conclusion, magnetic resonance imaging is important in the follow-up of chronological change as well as in original diagnosis of brain contusions.     

Magnetic resonance imaging in children with anorectal malformations: embryologic implications

Purpose: The aim of this study was to evaluate the spectrum of developmental anomalies in the caudal region of patients with anorectal malformations (ARM) and relate them to the new insights in the embryogenesis of this region. Methods: Forty-nine patients with ARM were investigated with magnetic resonance imaging (MRI); 24 preoperatively (preop) and 25 postoperatively (postop). Of this group, 17 patients had a high (or intermediate) ARM, 28 a low ARM, and 4 a cloacal malformation (CM). The evaluation of the imaging studies included the level and type of ARM (preop); the developmental state of the sphincter muscle complex (SMC); and the associated anomalies of spinal cord, spine, and urogenital system. The anomalies detected were ordered and related to recent embryologic observations in the caudal region. Results: With MRI, the level of ARM was depicted effectively in 23 of 24 patients (96%) investigated preop, including 5 of 9 clinically proven fistulae in those with high ARM and CM (56%). Maldevelopment of the SMC was observed in 14 of 49 patients (29%). Associated anomalies of spinal cord and spine were found in 51% of patients, more frequently in those with high ARM, low ARM with fistulae, and cloacal malformations. Associated anomalies of the urogenital system were found in 37% of patients. Conclusions: As illustrated by the current study, MRI has become indispensable for the visualization of the nature of congenital ARM and associated anomalies. Moreover, MRI aids in understanding the morphology and pathogenesis of these complex congenital malformations. Based on the MRI and recent embryologic observations, a new and simplified classification of ARM is introduced, including a more appropriate nomenclature. J Pediatr Surg 37:1138-1145.     

Magnetic resonance imaging with aneurysmal subarachnoid hemorrhage: comparison with computed tomography scan

Magnetic resonance studies of 27 consecutive preoperative and 33 postoperative patients with cerebral aneurysm and subarachnoid hemorrhage were reviewed. Magnetic resonance imaging using a 0.5- or 0.22-Tesla unit was at least as accurate as computed tomography scan for detection of acute subarachnoid hemorrhage. Magnetic resonance imaging was superior to computed tomography scan for demonstrating blood in the ventricles or posterior fossa subarachnoid space, transependymal migration of the cerebrospinal fluid, and several kinds of iatrogenic intracranial pathologies in postoperative patients. Ischemic lesions, particularly fresh lesions caused by delayed cerebral vasospasm, were much better shown on magnetic resonance imaging than on computed tomography scan. Nonferromagnetic Sugita clips caused significant artifacts, but the area of artifacts was consistently smaller, and a reasonable evaluation of structures relatively closer to the clip was possible with magnetic resonance imaging rather than computed tomography scan.     

Magnetic resonance imaging and the nonoperative treatment of spinal epidural abscess

This report describes three patients with spinal epidural abscess diagnosed by magnetic resonance imaging and treated nonoperatively. Prior to treatment, one patient was neurologically intact, one patient demonstrated a moderate neurological deficit, and one patient was severely paraparetic with loss of bladder and bowel control. Following identification of the pathogenic organism, antibiotic therapy was continued until the patients demonstrated clinical improvement and radiological resolution of the abscess. All patients remained stable or improved neurologically. Analysis of 33 previously reported patients treated with antibiotics suggests that nonoperative treatment may be a reasonable alternative therapy under certain clinical conditions. These include (1) identification of the pathogenic organism, (2) a stable neurological condition, (3) access to magnetic resonance imaging or computed tomography for potentially rapid reevaluation, and (4) appropriate neurosurgical consultation and nursing care. Nonoperative treatment may also be considered as a reasonable alternative for patients who have severe concurrent medical illness.     

分子磁共振成像在细胞移植治疗脑损伤研究中的应用

分子磁共振成像(molecularmagneticresonanceimaging ,mMRI)是活体状态在细胞和分子水平应用磁共振成像原理对生物过程进行定性和定量研究的新技术,能够对移植的细胞进行可视化追踪,可用于观察病变区神经再生情况。现就近年来分子磁共振成像在细胞移植治疗脑损伤研究中的进展作一综述。     

Magnetic resonance imaging implications of metal-reinforced spinal microcatheters

STUDY OBJECTIVE: To estimate the magnitude behavior of ferrous-alloy, wire-reinforced microcatheters for subarachnoid anesthesia and the possible hazards of exposing patients to magnetic resonance imaging (MRI) after accidental catheter fracture within the subarachnoid space. DESIGN: Open, qualitative in vitro study. SETTING: MRI facility of a university-affiliated medical center. MEASUREMENTS AND MAIN RESULTS: Measurements were made of the angular deflection of 28-gauge and 32-gauge TFX catheters from their resting alignment by a small bar magnet. Mobility of 28-gauge catheter fragments 3.0 to 3.5 cm in length and 3.3 to 4.0 mg in mass were tested (1) when lying free on a polished surface in an MRI magnetic field of 1.5 tesla and 60 cm from the magnetic casing, and (2) when mounted on a mildly viscous agar surface 40 to 50 cm from the magnetic casing. Catheters were attracted to a small bar magnet and could be pulled out of alignment by the magnetic attraction to a degree inversely proportional to their caliber. Catheter fragments released in a magnetic field of 1.5 tesla flew from a glass surface and attached themselves firmly to the magnet casing, while catheter fragments adhering to an agar surface were not levitated but were rotated from their resting orientation. CONCLUSIONS: The microcatheters under test exhibited marked magnetic properties. Two questions arise: First, should MRI be avoided in patients where broken TFX catheter fragments may lie partly or completely within the subarachnoid space? Second, should ferrous metallic strengthening wire be replaced by a nonmetallic fiber of comparable or greater tensile strength? Further in vitro studies are indicated to answer these questions.     

Magnetic resonance imaging and deep brain stimulation

OBJECTIVE: To determine whether cranial magnetic resonance imaging (MRI) is associated with deep brain stimulation (DBS) lead displacement or program interference. METHODS: In vitro and in vivo studies were performed with the Itrel II implantable pulse generator (IPG) (Model 7424; Medtronic, Minneapolis, MN), Medtronic 3387 and 3389 leads, and a 1.5-T GE Horizon LX scanner (General Electric, Milwaukee, WI). In the in vivo study, two MRI volumetric data sets were compared for each of five patients undergoing staged, bilateral, DBS electrode placement in the thalamic or subthalamic nucleus. The data sets were acquired shortly after the initial implantation and during stereotactic planning for the second implantation (1-8 mo between acquisitions). An additional thalamotomy-treated patient was included as a control patient. Volumetric data were analyzed in a blinded manner, using AnalyzeAVW 3.0 software (Biomedical Imaging Resource, Mayo Clinic, Rochester, MN), to determine lead movement. In the in vitro study, the IPG and leads were positioned in the magnetic field in various configurations and were systematically assessed for movement. RESULTS: In vivo, the majority of measured deviations (88%) were within the standard error of measurement (1.4 mm). The maximal measured deviation was 3 mm (2% occurrence). Excellent tremor control with stimulation was demonstrated, which did not change after MRI. In vitro, the DBS leads demonstrated no deflection when introduced into the magnetic field. Similarly, no changes in IPG battery strength, lead impedance, or program settings were observed. CONCLUSION: MRI was not associated with significant DBS electrode movement or changes in clinical responses. Other IPG models and components and MRI scanners should be evaluated, to develop specific guidelines for MRI among individuals with implanted DBS systems.     

脑内原发性淋巴瘤的MRI诊断

目的回顾性分析脑内原发性淋巴瘤MRI特点及病理改变,旨在提高对该病的MRI诊断水平。方法分析17例经手术病理证实的脑内原发性淋巴瘤的MRI表现,并与病理结果对照分析。结果(1)单发或多发病灶靠近中线区或脑表面,多发病灶占59%,易侵及额顶叶白质、胼胝体及基底节区;(2)T1WI呈低或稍低信号17例,T2WI呈等信号或稍高信号14例,占82%,坏死及出血少见;(3)灶周水肿及占位效应以轻度到中度为主;(4)强化方式以“握拳”样或团块状显著均匀强化为主,肿瘤可沿脑脊液播散。结论脑内原发性淋巴瘤的MRI表现具有一定的特异性,多数情况下综合分析可在术前作出正确诊断,但需与脑内多种疾病相鉴别。     

Magnetic resonance imaging in diffuse brain injury]

Forty cases diagnosed as diffuse brain injury (DBI) were studied by magnetic resonance imaging (MRI) performed within 3 days after injury. These cases were divided into two groups, which were the concussion group and diffuse axonal injury (DAI) group established by Gennarelli. There were no findings on computerized tomography (CT) in the concussion group except for two cases which had a brain edema or subarachnoid hemorrhage. But on MRI, high intensity areas on T2 weighted imaging were demonstrated in the cerebral white matter in this group. Many lesions in this group were thought to be edemas of the cerebral white matter, because of the fact that, on serial MRI, they were isointense. In mild types of DAI, the lesions on MRI were located only in the cerebral white matter, whereas, in the severe types of DAI, lesions were located in the basal ganglia, the corpus callosum, the dorsal part of the brain stem as well as in the cerebral white matter. As for CT findings, parenchymal lesions were not visualized especially in mild DAI. Our results suggested that the lesions in cerebral concussion were edemas in cerebral white matter. In mild DAI they were non-hemorrhagic contusion; and in severe DAI they were hemorrhagic contusions in the cerebral white matter, the basal ganglia, the corpus callosum or the dorsal part of the brain stem.     

Magnetic resonance imaging of experimental rat brain tumors: Histopathological evaluation

Using RG-C6 glioma-transplanted rats, we studied precontrast and postcontrast magnetic resonance imaging, extravasation of Evans blue, and histology. In all rats, tumor was enhanced with gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA). The necrotic portion in the tumor, however, was not enhanced. Hemorrhage and hydrocephalus were clearly visualized on both the precontrast and postcontrast images. Blood-brain barrier-disrupted areas stained with Evans blue and areas enhanced with Gd-DTPA on magnetic resonance imaging were nearly consistent. It is suggested that the mechanism of brain tumor enhancement with Gd-DTPA on magnetic resonance imaging is simply related to the degree of alteration of the blood-brain barrier. The Gd-DTPA-enhanced magnetic resonance imaging, even with low magnetic field, is useful for the evaluation of size, shape, and location of experimental rat brain tumors.     

Magnetic resonance imaging of experimental brain edema in cats

The authors observed the natural course of experimental brain edema in vivo using magnetic resonance (MR) imaging. To detect and qualify the edematous lesion, they obtained images by the spin echo technique (repetition time, 2100 ms; echo time, 80 ms). These showed the maximal brain edema on the 1st to 3rd days after the operation, as evidenced by a pixel density study and a finding of mass effect. On MR images enhanced with manganese, the inversion recovery technique (repetition time, 2100 ms; inversion time, 500 ms) demonstrated the edematous lesion as a high signal intensity area with good spatial resolution. Moreover, the follow-up inversion recovery images with manganese suggested that there was a system for absorption of edema fluid between blood vessels and the edematous lesion. The authors think that MR imaging is an important technique for observation of the dynamics of experimental brain edema.     

Magnetic resonance imaging of a fat embolism of the brain: case report

A 22-year-old man developed fat embolism syndrome. Although a computed tomographic (CT) scan of the brain showed nothing abnormal, a magnetic resonance imaging scan detected scattered spotty areas of low intensity on T1-weighted images and of high intensity on T2-weighted images. Magnetic resonance imaging is thought to be more sensitive than computed tomography in detecting cerebral fat embolism syndrome and correlates well with the clinical course.     

Magnetic resonance imaging of the brain stem in adolescent idiopathic scoliosis

The cause of adolescent idiopathic scoliosis remains an enigma. Several studies have demonstrated abnormalities of posture, proprioception, and equilibrium control in patients with adolescent idiopathic scoliosis. These functions are integrated by structures in and around the brain stem. Twenty-seven patients with adolescent idiopathic scoliosis were studied with magnetic resonance imaging to delineate the anatomy of the brain stem in such patients. Imaging was conducted from the hypothalamus to the spinal cord at C3 in 26 patients; the remaining patient underwent an incomplete study because of a claustrophobic reaction. The study group consisted of 25 females and 2 males with an average age of 16 + 5 years. There were 19 right thoracic curves, 5 thoracolumbar curves, and 3 left lumbar curves. The mean primary curve size was 27 degrees at the most recent clinical evaluation. Seven patients were treated with observation, 14 with bracing, and 6 with surgery. The magnetic resonance imaging studies were read independently by three attending radiologists in a randomized, blinded fashion along with the magnetic resonance imaging studies of 11 controls. Asymmetry in the ventral pons or medulla in the area of the corticospinal tracts was noted in seven study patients and one control; one study patient had an enlarged cisterna magna and one an inconclusive (incomplete) study. These findings may support previous studies that have suggested a central nervous system abnormality as a cause of adolescent idiopathic scoliosis.     

Magnetic resonance imaging detects and predicts early brain injury after subarachnoid hemorrhage in a canine experimental model

Abstract The canine double hemorrhage model is an established model to study cerebral vasospasm, the late sequelae of subarachnoid hemorrhage (SAH). The present study uses magnetic resonance imaging (MRI) to examine the recently reported early brain injury after SAH. Double hemorrhage SAH modeling was obtained by injecting 0.5 mL/kg of autologous arterial blood into the cisterna magna of five adult mongrel dogs on day 0 and day 2, followed by imaging at day 2 and day 7 using a 4.7-Tesla (T) scanner. White matter (WM) showed a remarkable increase in T2 values at day 2 which resolved by day 7, whereas gray matter (GM) T2 values did not resolve. The apparent diffusion coefficient (ADC) values progressively increased in both WM and GM after SAH, suggestive of a transition from vasogenic to cytotoxic edema. Ventricular volume also increased dramatically. Prominent neuronal injury with Nissl's staining was seen in the cortical GM and in the periventricular tissue. Multimodal MRI reveals acute changes in the brain after SAH and can be used to non-invasively study early brain injury and normal pressure hydrocephalus post-SAH. MR can also predict tissue histopathology and may be useful for assessing pharmacological treatments designed to ameliorate SAH.     

Magnetic resonance imaging of the knee: correlation with arthroscopy

Magnetic resonance imaging (MRI) was used to diagnose acute and chronic intraarticular knee pathology in 23 knees. The results were compared with arthroscopic findings of meniscal, ligamentous, and articular cartilaginous pathology using a double-blind prospective protocol. The overall accuracy for meniscal tears was 78%, with a sensitivity of 88% and a specificity of 72%; for cruciate ligaments, MRI was 82% accurate, with a sensitivity of 67% [anterior cruciate ligament (ACL) only] and a specificity of 86%. In select clinical situations, MRI of the knee is a useful diagnostic tool.