Joubert综合征的MRI及DTI表现(附2例报告并文献复习)

目的探讨Joubert综合征的MRI及扩散张量成像(DTI)表现,提高对该病的认识。资料与方法回顾性分析2例Joubert综合征患儿的临床资料、MRI及DTI表现。结果 Joubert综合征的MRI表现包括小脑"中线裂"、中脑"臼齿征"和第四脑室扩大。DTI显示小脑上脚纤维束孤立单侧走行,在中脑内缺乏左右走向水平交叉。结论 Joubert综合征的常规MRI征象具有特征性,DTI可以直接观察纤维束走行异常,提供解剖学证据。     

Magnetic resonance experience of a twin pregnancy with a normal fetus and hydatidiform mole: a case report

A case of twin pregnancy with a coexistent hydatidiform mole after in vitro fertilization is presented. Prenatal magnetic resonance (MR) imaging at 20 gestational weeks demonstrated a normal fetus and a distinct junction between the molar tissue and myometrium suggesting no evidence of myometrial invasion. Clinically, the rare disease entity involves a high risk of maternal complications and intrauterine fetal death. The application of ultrafast MR imaging for prenatal examination provides important additional information for prenatal counseling and obstetric management.     

MR imaging and spectroscopic study of epileptogenic hypothalamic hamartomas: analysis of 72 cases

BACKGROUND AND PURPOSE: Reports of MR imaging in hypothalamic hamartomas associated with epilepsy are few, and the number of patients studied is small. We aimed to detail the relationship of hypothalamic hamartomas to surrounding structures, to determine the frequency and nature of associated abnormalities, and to gain insight into mechanisms of epileptogenesis. METHODS: We systematically examined MR imaging studies of 72 patients with hypothalamic hamartoma and refractory epilepsy (patient age, 22 months to 31 years). A dedicated imaging protocol was used in 38 cases. Proton MR spectroscopy of the hypothalamic hamartoma was performed for 19 patients and compared with the metabolite profile of the thalamus in 10 normal children and the frontal lobe in 10 normal adults. RESULTS: Compared with normal gray matter, hypothalamic hamartomas were hyperintense on T2-weighted images (93%), hypointense on T1-weighted images (74%), and had reduced N-acetylaspartate and increased myoinositol content shown by MR spectroscopy. Hypothalamic hamartomas always involved the mammillary region of the hypothalamus, with attachment to one or both mammillary bodies. Intrahypothalamic extension (noted in 97%) tended to displace the postcommissural fornix and hypothalamic gray matter anterolaterally, such that the hypothalamic hamartomas nestled between the fornix, the mammillary body, and the mammillothalamic tract. Larger hamartoma size was associated with central precocious puberty. Associated findings of questionable epileptic significance included anterior temporal white matter signal intensity abnormalities (16%) and arachnoid cysts (6%). Malformations of cortical development were observed in only two patients, and hippocampal sclerosis was not observed. CONCLUSIONS: Hypothalamic hamartomas can be readily distinguished from normal hypothalamic gray and adjacent myelinated fiber tracts, best appreciated on thin T2-weighted images. MR imaging and spectroscopy suggest reduced neuronal density and relative gliosis compared with normal gray matter. Associated epileptogenic lesions are rare, supporting the view that the hypothalamic hamartoma alone is responsible for the typical clinical features of the syndrome. The intimate relationship to the mammillary body, fornix, and mammillothalamic tract suggests a role for these structures in epileptogenesis associated with hypothalamic hamartomas.     

Myelomeningocele: prenatal evaluation--comparison between transabdominal US and MR imaging

PURPOSE: To compare transabdominal ultrasonography (US) with fetal magnetic resonance (MR) imaging in the prenatal evaluation of myelomeningocele lesion level. MATERIALS AND METHODS: Prenatal US images, pre- and postnatal MR images, and postnatal spinal radiographs obtained in the first 100 fetuses who underwent intrauterine myelomeningocele repair were the basis for this study. Each image was used to assign a lesion level. The assigned levels were compared by means of the kappa statistic, as an index of agreement. RESULTS: All fetuses underwent prenatal US. Sixty-one fetuses underwent prenatal MR imaging. Fifty fetuses underwent both postnatal spinal radiography and postnatal MR imaging, and an additional 34 fetuses underwent one postnatal study but not the other. When findings on prenatal US images were compared with those on postnatal radiographs, the findings agreed within one spinal level in 79% (55 of 70, kappa = 0.60) of cases. When findings on prenatal MR images were compared with those on postnatal radiographs, the findings agreed in 82% (31 of 38, kappa = 0.63) of cases. Findings on postnatal MR images and those on postnatal spinal radiographs agreed within one spinal level in 100% (50 of 50, kappa = 1.0) of cases. CONCLUSION: Findings at prenatal MR imaging and prenatal US are equally accurate for the assignment of a lesion level in a fetus with myelomeningocele. Given that findings with both modalities will lead to misdiagnosis of the spinal level by two or more segments in at least 20% of cases, care should be exercised when neurologic outcome is predicted on the basis of these studies alone.     

Interpeduncular heterotopia in Joubert syndrome: a previously undescribed MR finding

The so-called molar tooth sign is the radiologic hallmark of JSRD. Joubert syndrome is a rare, most often autosomal-recessive disorder with a characteristic malformation of the midhindbrain. We describe 3 patients with JSRD and the additional MR finding of tissue resembling heterotopia in the interpeduncular fossa, which in one patient was combined with a more extensive intramesencephalic heterotopia. Interpeduncular heterotopia has not been reported previously, either in the context of JSRD or as a separate entity. This new imaging feature enlarges the spectrum of brain stem abnormalities in JSRD. In view of the underlying ciliopathy, it seems likely that the interpeduncular heterotopia results from misdirected migration.     

Fetal anomalies: comparison of MR imaging and US for diagnosis

PURPOSE: To compare prenatal ultrasonography (US) and magnetic resonance (MR) imaging for the diagnosis of fetal anomalies. MATERIALS AND METHODS: Images of 27 fetuses (28 diagnostic cases) with anomalies diagnosed at US were evaluated; in these fetuses, prenatal MR imaging was performed within 15 days of US. Prenatal US and MR imaging findings were compared with postnatal diagnoses. Postnatal evaluation included US, MR imaging, autopsy, surgery, voiding cystourethrography, computed tomography, angiography, and physical examination. RESULTS: In seven diagnostic cases, US and MR imaging findings were in complete agreement with postnatal diagnoses. MR imaging correctly provided additional information to the US-determined diagnosis in another seven and correctly changed the US diagnosis in three. The MR imaging-determined diagnosis was incorrect and the US diagnosis was correct in four cases. In seven cases, the diagnoses at both US and MR imaging were incorrect when correlated with the postnatal outcome. MR imaging was most valuable in the assessment of anomalies of the central nervous system. CONCLUSION: MR imaging may have a place as an adjunct to US in evaluation of fetal anomalies, particularly those involving the central nervous system.     

Benign and malignant tumor of the uterine body with broccoli sign: MR imaging features for differential diagnosis

The characteristic morphology called broccoli sign combines a stalk and prolapsed tumor and is a useful diagnostic indicator of prolapsed tumor of the uterine body. Magnetic resonance (MR) imaging findings of broccoli sign are common for uterine submucosal leiomyomata but not well described for other tumors of the endometrial cavity, such as endometrial polyp, atypical polypoid adenomyoma, endometrial carcinoma, carcinosarcoma, and adenosarcoma. Both benign and malignant masses of the uterine body can show broccoli sign. The MR imaging features of prolapsed uterine tumor with broccoli sign resemble those of usual uterine body tumors, but the location is different. We describe the MR imaging features of prolapsed uterine tumors with broccoli sign.     

Pre- and postnatal MR imaging of hypothalamic hamartomas associated with arachnoid cysts

We describe two cases of hypothalamic hamartoma associated with arachnoid cysts. One case was initially documented on prenatal MR images. Because of the rarity of the association and resultant distortion in regional anatomy, the solid component of the mass may be overlooked. This would certainly be true when using lower-resolution diagnostic studies such as fetal MR imaging. The lesion could also be confused with a cystic tumor such as pilocytic astrocytoma. Thorough evaluation is required in patients with precocious puberty, gelastic seizures, and the presence of a suprasellar arachnoid cyst.     

MRI诊断膝关节半月板桶柄状撕裂

目的:总结分析半月板桶柄状撕裂的MRI征象和诊断价值.方法:回顾性分析146个经关节镜证实的膝关节MR图像,其中28个膝关节存在半月板桶柄状撕裂,记录如下5种MRI征象:碎块内移征、外周残半月板征、双PCL征、空领结征及双前角征,并分别计算每种征象诊断半月板桶柄状撕裂的敏感度、特异度、准确度、阳性预测值和阴性预测值.结...     

Cemento-ossifying fibroma presenting as a mass of the parapharyngeal and masticator space.

We report a case of cemento-ossifying fibroma that presented as a large extraosseous mass in the masticator and parapharyngeal space. CT scanning and MR imaging showed a large extraosseous mass with central conglomerated, well-matured ossified nodules and fatty marrow. The central matured ossified nodules were of low density on CT scans and high signal intensity on T1- and T2-weighted MR images. Multiplanar reformatted CT scans revealed the origin of the mass to be at the extraction site of the right lower second molar tooth.     

Diagnostic Value of Prenatal MR Imaging in the Detection of Brain Malformations in Fetuses before the 26th Week of Gestational Age

BACKGROUND AND PURPOSE:In several countries, laws and regulations allow abortion for medical reasons within 24–25 weeks of gestational age. We investigated the diagnostic value of prenatal MR imaging for brain malformations within 25 weeks of gestational age.MATERIALS AND METHODS:We retrospectively included fetuses within 25 weeks of gestational age who had undergone both prenatal and postnatal MR imaging of the brain between 2002 and 2014. Two senior pediatric neuroradiologists evaluated prenatal MR imaging examinations blinded to postnatal MR imaging findings. With postnatal MR imaging used as the reference standard, we calculated the sensitivity, specificity, positive predictive value, and negative predictive value of the prenatal MR imaging in detecting brain malformations.RESULTS:One-hundred nine fetuses (median gestational age at prenatal MR imaging: 22 weeks; range, 21–25 weeks) were included in this study. According to the reference standard, 111 malformations were detected. Prenatal MR imaging failed to detect correctly 11 of the 111 malformations: 3 midline malformations, 5 disorders of cortical development, 2 posterior fossa anomalies, and 1 vascular malformation. Prenatal MR imaging misdiagnosed 3 findings as pathologic in the posterior fossa.CONCLUSIONS:The diagnostic value of prenatal MR imaging between 21 and 25 weeks'' gestational age is very high, with limitations of sensitivity regarding the detection of disorders of cortical development.

Prenatal MR imaging of the brain is a technique increasingly used in clinical practice; it is generally performed as a second-look investigation in case of abnormal or suspicious findings at prenatal ultrasonography (US).¹Prenatal MR imaging is often advocated as an important tool in parental counseling and decision-making regarding the fate of the pregnancy.² In several countries, crucial decisions on pregnancy must be made before the 24th to 25th week of gestation because local laws and regulations allow abortion for medical reasons within this deadline. In these cases, a correct diagnosis should be reached early during pregnancy because performing additional MR imaging follow-up is not compatible with legal time constraints. Moreover, an early correct diagnosis may have an important impact on the psychological well-being of the mother and may help the clinician in planning other diagnostic or therapeutic procedures.To determine prenatal MR imaging accuracy, several studies have already compared its results with ones from postmortem examinations,^3–5 postnatal MR imaging,^6–11 or both postmortem examination and postnatal MR imaging.^12,13 However, these studies were performed in small cohorts of fetuses, and they were focused on a single specific class of anomalies or accounted for few fetuses younger than 24–25 weeks'' gestational age (GA), thus providing little information about the diagnostic accuracy of prenatal MR imaging performed at an early GA.The purpose of our study was to assess the diagnostic value of prenatal MR imaging in the diagnosis of brain malformations, in a large cohort of fetuses (109 cases) within 25 weeks of GA, by using postnatal MR imaging as the reference standard.     

MR imaging of fetal abnormalities.

Our purpose was to evaluate the capability of ultrafast single-shot fast spin-echo MR imaging to assess normal fetal anatomy and abnormalities of different fetal organ systems. Fetal MR imaging was performed prospectively in consecutive 40 pregnant women because of abnormal findings or suspected fetal abnormalities on prenatal US. No statistically significant difference between US and MR imaging was found for the detection of abnormality in any organ system. MR imaging was slightly superior to US with regard to cerebral abnormalities only. In four (10%) of 40 fetuses, additional information provided by MR imaging altered counseling. However, MR imaging of the extremities-face and soft tissues was limited because of the lack of real-time information.     

Ultrafast MR imaging of the fetus

OBJECTIVE: We examined the capability of ultrafast single-shot fast spin-echo imaging to assess different fetal organ systems compared with prenatal sonography, using autopsy or postpartum imaging as a standard of reference. SUBJECTS AND METHODS: Thirty women with complicated pregnancies (mean age of gestation, 190 +/- 54 days) underwent T2-weighted ultrafast MR imaging. MR images were analyzed with regard to diagnostic confidence in assessing abnormalities of fetal organ systems, and data were correlated with postpartum findings or necropsy. Results were compared with those of prenatal sonography. RESULTS: Using receiver operating characteristic curve analysis, diagnostic confidence of MR imaging was best for assessing the brain (area under the curve [Az] = 0.96) and spinal canal (Az = 1.0), uteroplacental unit (Az = 0.93), and lungs (Az = 0.91). Results for the heart (Az = 0.63) and extremities (Az = 0.77) were significantly lower than that of other organs (p < 0.001). Diagnostic accuracy increased with gestational age. No statistically significant difference between sonography and MR imaging was found for the detection of abnormality in any organ system. In three fetuses, MR imaging was superior to sonography in characterizing cerebral abnormalities. MR imaging was inferior to sonography in characterizing abnormalities of the heart and extremities. CONCLUSION: Our results indicate that ultrafast MR imaging can be used for in vivo fetal imaging, especially in assessing cerebral abnormalities. However, MR imaging should be restricted to situations in which sonographic findings are ambiguous or impaired.     

MR imaging and ultrasound of fetal cervical cystic lymphangioma: utility in antepartum treatment planning

We present a case of fetal cystic lymphangioma that was initially diagnosed by ultrasonography and further evaluated by prenatal MR imaging. MR imaging findings aided in improved delineation of the neck mass. T2-weighted MR images revealed partial compression of the airway by the neck mass. This information was useful in the decision to use ex utero intrapartum treatment (EXIT) and helped surgeons in planning their approach to establish airway control during delivery.     

Muscular sarcoidosis

There are four types of muscular sarcoidosis: nodular, chronic myopathy, acute myositis, and asymptomatic. The nodular type is important because it may be confused with a soft tissue tumor. Magnetic resonance (MR) imaging provides specific findings. A star-shaped central structure of decreased signal intensity, a "dark star" sign, is seen on the axial images. A long nodule with an inner stripe of decreased signal intensity and outer stripes of increased signal intensity, a "three stripes" sign, is seen on the coronal and sagittal images. In the chronic myopathy type, the role of MR imaging is limited. Gallium scintigraphy, which reflects activity of inflammation, may show increased uptake. In the acute myositis type, MR imaging shows increased signal intensity, and gallium scintigraphy shows increased uptake; however, these findings are nonspecific.     

MR imaging of brain-stem hypoplasia in horizontal gaze palsy with progressive scoliosis

We present the MR imaging findings of a girl with horizontal gaze palsy and progressive scoliosis (HGPPS). HGPPS is a rare congenital disorder characterized by absence of conjugate horizontal eye movements and accompanied by progressive scoliosis developing in childhood and adolescence. MR imaging depicted brain-stem hypoplasia with absence of the facial colliculi, presence of a deep midline pontine cleft (split pons sign), and a butterfly configuration of the medulla. These MR imaging features suggest the diagnosis of HGPPS and correlate with the clinical findings. We hypothesize that maldevelopment of dorsomedial brain-stem structures plays a crucial role in the pathogenesis of HGPPS.     

下丘脑错构瘤的MR诊断与临床表现

目的：分析下丘脑错构瘤的MRI表现,探讨其临床表现、病理及MRI表现的关系,以提高对本病的认识。方法：回顾性分析了14例下丘脑错构瘤的MR及临床资料,其中男6例,女8例,年龄1～37岁。均进行了MR常规扫描和增强扫描,均经病理证实。结果：14例病灶中以宽基底附于第三脑室底部、灰结节和乳头体者6例,有＂蒂＂错构瘤6例,1例位于鞍背后方,1例异位于视交叉上方,所有病例均呈等T1WI信号,等或稍长T2WI信号,信号较均匀,边界较清晰。结节状或类圆形者9例,不规则形5例。直径〈15mm者10例,〉15mm者4例,最大直径2.9cm。2例有明显占位效应,向上压迫三脑室,向前压迫垂体柄或视交叉。结论：当患者出现性早熟和（或）痴笑样癫痫为主的临床表现,MRI显示灰结节和乳头体肿块并典型信号改变且无明显强化时,应首先考虑本病。     

MR 'hot nose sign' and 'intravascular enhancement sign' in brain death.

Three cases of MR with gadopentetate dimeglumine in patients diagnosed with cerebral death are presented. Observation of an MR "hot nose sign" and an "intravascular enhancement sign" provided additional imaging support in the clinical diagnosis of brain death. The MR findings in brain death include: 1) transtentorial and foramen magnum herniation, 2) absent intracranial vascular flow void, 3) poor gray matter/white matter differentiation, 4) no intracranial contrast enhancement, 5) carotid artery enhancement (intravascular enhancement sign), and 6) prominent nasal and scalp enhancement (MR hot nose sign). Additional modalities for confirming brain death are discussed.