CT and MR imaging features of adnexal torsion.

In adnexal torsion, the ovary, ipsilateral fallopian tube, or both twist with the vascular pedicle, resulting in vascular compromise. Unrelieved torsion is likely to cause hemorrhagic infarction as the degree of arterial occlusion increases. Therefore, early diagnosis is important to preserve the affected ovary. Adnexal torsion commonly accompanies an ipsilateral ovarian neoplasm or cyst but can also occur in normal ovaries, usually in children. Although ultrasonography is typically the initial emergent examination, computed tomography (CT) and magnetic resonance (MR) imaging may also be useful diagnostic tools. Common CT and MR imaging features of adnexal torsion include fallopian tube thickening, smooth wall thickening of the twisted adnexal cystic mass, ascites, and uterine deviation to the twisted side. Uncommon imaging findings in adnexal torsion that are specific to hemorrhagic infarction include hemorrhage in the thickened fallopian tube, hemorrhage within the twisted ovarian mass, and hemoperitoneum. Additional imaging findings that can suggest hemorrhagic infarction include eccentric smooth wall thickening exceeding 10 mm in a cystic ovarian mass converging on the thickened fallopian tube and lack of contrast enhancement of the internal solid component or thickened wall of the twisted ovarian mass. Early diagnosis can help prevent irreversible structural damage and may allow conservative, ovary-sparing treatment.     

脑胶质母细胞瘤的MRI表现

目的 分析胶质母细胞瘤的MRI影像学特点,提高对该病的认识和诊断、鉴别诊断水平.方法 回顾性分析术后病理诊断为脑胶质母细胞瘤的病例17例,对其临床及MRI特点进行总结分析.结果 本组病例均表现为巨大团块样占位,病灶大部呈长T1长T2信号改变,信号不均匀,其中突破中线结构者5例,边缘欠规整,呈显著不均匀强化者13例,病灶边缘较清晰,强化效应相对均匀者4例.结论 胶质母细胞瘤MRI特点鲜明,可作为其诊断依据.     

MR imaging features of breast lymphoma

Mammographic, ultrasonographic and MR imaging features in a patient with non-Hodgkin's lymphoma are reported in this paper. Mammography and ultrasonography revealed ill-defined, round masses with skin thickening. Precontrast T1W images demonstrated multiple well-defined, hypointense masses, which showed rapid rim enhancement in dynamic postcontrast sequence. The enhancement rate indicated malignant pathology. MR imaging demonstrated the extent of involvement more apparently than conventional imaging. Although, not pathognomonic for lymphoma, MR imaging may be helpful in evaluation and follow-up of breast masses in patients with previous lymphoma.     

MR imaging features of Nipah encephalitis

OBJECTIVE: The newly discovered Nipah virus causes an acute febrile encephalitic illness in humans that is associated with a high mortality. The purpose of this study is to describe the MR imaging findings of Nipah encephalitis. MATERIALS AND METHODS: MR imaging of the brain was performed in 31 patients with Nipah encephalitis divided into three groups. The first group (14 patients) underwent MR imaging during the acute phase of the illness and the second group (10 patients) during the later phase of the acute illness. The third group consisted of six patients who underwent MR imaging because they experienced neurologic relapse and one patient who had late-onset encephalitis. Spin-echo T1- and T2-weighted sequences and T2-weighted fluid attenuated inversion recovery (FLAIR) sequences were performed. Contrast-enhanced MR imaging was performed in four patients. RESULTS: The FLAIR sequences revealed abnormalities in all patients studied. MR imaging findings in both the acute and later phases of encephalitis were similar; the main feature of both phases was the presence of discrete high-signal-intensity lesions, measuring 2-7 mm, disseminated throughout the brain, mainly in the subcortical and deep white matter of the cerebral hemispheres. Neither mass effect nor cerebral edema was seen. There was no correlation with the focal neurologic signs, depth of coma, and outcome of the patients. The lesions were attributed to widespread microinfarctions from underlying vasculitis of cerebral small vessels. Features found on MR imaging in relapsed and late-onset encephalitis differed from the features in acute encephalitis in that confluent cortical involvement was the prominent finding in the former, as opposed to discrete focal lesions in the subcortical and deep white matter in the latter. CONCLUSION: MR imaging is a sensitive and specific diagnostic tool for evaluating Nipah encephalitis.     

MR imaging features of solid-pseudopapillary tumor of the pancreas.

Solid-pseudopapillary tumor (SPT) of the pancreas is characterized as cystic, necrotic, and hemorrhagic degeneration. In this study, magnetic resonance (MR) findings of 4 cases were reviewed. Patchy or spotty areas of high intensity that suggested hemorrhagic degeneration were constantly detected on fat-suppressed T(1)-weighted images. Dynamic contrast-enhanced MR imaging revealed mild and gradual increase of contrast enhancement in solid portions. Multi-contrast MR imaging that included fat-suppressed T(1)-weighted imaging and dynamic contrast-enhanced imaging allowed accurate diagnosis of SPT and its differentiation from other tumors.     

Deltoid contracture: MR imaging features

AIM: To describe the magnetic resonance imaging (MRI) features of deltoid contracture and compare these findings with the operative and histological findings and to determine the utility of MRI for diagnosis and treatment planning. PATIENTS AND METHODS: Retrospective review of clinical and imaging in six patients with deltoid contracture, as well as the operative and histological findings of four operated patients. RESULTS: Magnetic resonance imaging clearly demonstrated the intramuscular fibrous bands of the deltoid as a homogeneously hypointense area with distinctive margins on T1-, T2- and T2*-weighted images. Operative findings were exactly consistent with the findings observed by MRI. CONCLUSION: Deltoid contracture is best evaluated with MRI which facilitates visualization of the intramuscular fibrous bands being pathognomonic of this entity and may provide information useful in treatment planning.     

Chondrosarcomas of the skull base: MR imaging features.

The magnetic resonance (MR) images from 17 patients with chondrosarcomas of the skull base were retrospectively reviewed to characterize the size, location, signal intensity, and extension of these tumors. Eleven patients with chondrosarcomas received intravenously administered gadopentetate dimeglumine. In 16 patients, computed tomographic (CT) scans were obtained to evaluate intratumorous mineralization and bone erosion. On short repetition time (TR)/echo time (TE) MR images, chondrosarcomas generally had low to intermediate signal intensity; on long TR/TE MR images, they generally had very high signal intensity. Signal heterogeneity on long TR/TE MR images was seen in 10 of 17 tumors (59%) and was caused by matrix mineralization, fibrocartilaginous elements, or both. Matrix mineralization was demonstrated with CT in seven of the 16 chondrosarcomas. Chondrosarcomas showed marked enhancement after administration of gadopentetate dimeglumine in either a heterogeneous (n = 8) or homogeneous (n = 3) pattern. The information about the size and extent of these neoplasms was important in the choice of surgical approaches for gross total resection of tumor.     

Trigeminal neuralgia: MR imaging features

Magnetic resonance (MR) imaging was used to evaluate the relationship of the cisternal portion of the fifth cranial nerve to surrounding vascular structures in six patients with documented trigeminal neuralgia and in 85 asymptomatic patients. MR imaging clearly demonstrated the course of the fifth nerve from its root entry zone (REZ) to the Meckel cave and its relationship to the surrounding vertebrobasilar system. In the six patients with trigeminal neuralgia, the presence of a vascular structure at the REZ of the fifth nerve was identified. In the 85 asymptomatic patients, examination of 170 trigeminal nerves revealed that 30% had contact between a vascular structure and the fifth nerve at the REZ, but only 2% had actual deformity. These results indicate that although neurovascular contact may be asymptomatic, MR demonstration of a vascular structure at the REZ of the fifth cranial nerve in a patient with trigeminal neuralgia may implicate this as the cause of symptoms, which may influence the treatment of choice. Because of the inherent limitations of computed tomography in the visualization of posterior fossa structures, MR imaging should be considered the initial screening procedure in the assessment of patients with trigeminal neuralgia.     

Dermatofibrosarcoma protuberans: MR imaging features

OBJECTIVE: The objective of our study was to describe the MR imaging features of 10 cases of histologically confirmed dermatofibrosarcoma protuberans. CONCLUSION: MR imaging is useful in identifying the extent and location of dermatofibrosarcoma protuberans. Although most cases of this tumor are superficial and well defined, we have shown three cases in which the tumor was in a deep location and one case in which the tumor was ill defined in appearance. Knowledge of the variable MR imaging appearances of these tumors may aid in the diagnosis of difficult or atypical cases.     

Hemifacial spasm: MR imaging features

MR imaging was used to evaluate the relationship of the root exit zone of the seventh cranial nerve to surrounding vascular structures in 13 patients with clinically documented hemifacial spasm and in 70 asymptomatic patients. MR imaging clearly demonstrated the course of the seventh nerve from the root exit zone of the brainstem to the internal auditory canal and its relationship to the surrounding vertebrobasilar system. The presence of a vascular structure at the root exit zone of the seventh nerve was identified in all 13 patients with hemifacial spasm. In the 70 asymptomatic patients, examination of 140 seventh nerves revealed that 21% had contact by a vascular structure at the root exit zone of the seventh nerve. Our results indicate that although neurovascular contact may be asymptomatic, MR demonstration of a vascular structure at the root exit zone of the seventh cranial nerve in a patient with hemifacial spasm may implicate neurovascular compression as the cause of symptomatology. This finding may alter therapeutic management. Because of the inherent limitations of CT in the visualization of posterior fossa structures, MR imaging should be considered the initial screening procedure in the assessment of patients with hemifacial spasm.     

脑裂畸形的MR影像征象分析(附32例报告)

目的：探讨脑裂畸形的MR影像特征。方法：回顾性分析32例脑裂畸形的MR表现。结果：本组32例，共42例裂隙，融合型29侧，分离型13例，其MR影像表现为横贯一侧或双侧大脑半球并衬有灰质的裂隙，裂隙外侧端脑表面常见楔形缺损（36／42），其位置大多数在大脑半球凸面中部三分之一（29／42），裂隙内侧端脑室缘呈幕状突起（19／42）或突向脑室腔的灰质块（15／42），裂隙常与侧裂池相连（26／42），二者位置关系呈直线裂，直角型及锐角型三种类型，直角型最常见。绝大多数病例侧脑室扩大（29／32），其中17例对称性扩大。12例美丽 灶侧脑室扩大更明显，合并透明隔缺如28例，灰质异位11例，多微小脑回7例，结论：脑裂畸形的MR影像征象具有特征性，目前是诊断脑裂畸形的金标准。     

节细胞神经瘤的影像学表现

目的 探讨节细胞神经瘤的CT和MR表现.方法 回顾性分析18例经手术病理证实的节细胞神经瘤的CT、MR影像学资料,所有患者均接受CT平扫及增强扫描,2例接受MR平扫.结果 节细胞神经瘤好发于中青年,位于后纵隔8例,肾上腺5例,腹膜后4例,颈部1例.均为单发病灶、边界清楚,嵌入式生长可呈多种形态.CT平扫:12例为均匀低密度,平均CT值22～37 HU;6例密度不均,平均CT值13～46 HU,其中2例伴有坏死、囊变.2例见斑点状钙化.增强扫描:肿瘤各期均无强化4例,仅动脉期轻度强化5例,仅静脉期轻度强化2例,静脉期及延迟期呈轻、中度渐进性强化1例,三期呈渐进性强化6例;坏死及囊变部分未见强化.2例肿瘤内见肋间后动脉穿行,1例见腰动脉穿行并见细小分支滋养肿瘤.2例下腔静脉推挤受压移位,1例见颈部大血管被包绕.MR平扫:1例信号均匀,1例信号不均;T1WI表现为低信号,T2 WI呈高信号为主,脂肪抑制(SPIR)及扩散加权成像(DWI)呈高信号.结论 节细胞神经瘤的CT及MR表现具有一定特征性,尤其是CT示肿瘤为均匀低密度、伴有斑点状钙化、肿瘤内血管穿行但未受侵,增强扫描动脉期无明显强化或轻度强化,呈渐进性强化方式,DWI示肿瘤呈高信号时,应考虑节细胞神经瘤的可能.     

脊髓亚急性联合变性的MRI诊断要点分析

目的分析脊髓亚急性联合变性(SCD)的MRI诊断要点。资料与方法回顾性分析15例临床确诊SCD的病人临床及MRI资料,分析其脊髓MRI表现特点,统计分析SCD病人受累脊髓节段数与血清VB12水平、发病时间的相关性。结果 15例SCD病人均于横断面影像上显示颈胸段脊髓对称性等或长T1、长T2信号,13例病变主要位于颈胸段水平脊髓后索,2例同时累及后索、侧索及前索。但于横断面T2WI上颈段与胸段脊髓异常信号形态各具特点。颈段脊髓受累时于横断面T2WI上呈脊髓内"倒V"形或"反兔耳"形的对称性高信号。胸段脊髓受累时于横断面T2WI上呈脊髓内"哑铃"形的对称性高信号。统计学分析显示15例SCD病人脊髓受累节段数与血清VB12水平呈负相关,而与病程长短无相关性。结论脊髓MR成像对于SCD脊髓疾病的诊断有重要价值。     

MR imaging features of spindle cell lipoma

Objective

To assess the MR imaging features of spindle cell lipomas (SCL) and to compare these appearances directly with the histopathological findings.

Materials and methods

A retrospective review of our soft tissue tumor database was performed. This yielded 1,327 histologically proven lipomas, of which 25 were confirmed as being SCLs. Fourteen of the 25 patients had MR examinations available for review and only these patients were included in our study. Lesions were assessed at MR examination for the degree of internal fat signal content with grade 0 representing 0 % fat signal and grade 4 100 % fat signal. The degree of fat suppression and contrast-enhancement pattern were also recorded. The excision specimens were independently reviewed by a consultant histopathologist. The histology specimens were assessed for the amount of internal fat and non-adipose tissue and graded using the same scale applied for the imaging. Where core needle biopsy (CNB) was performed, the CNB specimens were also examined for positive features of SCL.

Results

In our study, 93 % (13/14) of our patients were male and the average age was 58 years. 65 % (9/14) of the lesions presented in the upper back, shoulder, or neck. All lesions were subcutaneous. 35 % (5/14) of the SCLs demonstrated grade 3 (>75 %) or grade 4 (100 %) fat signal on MR examination. 35 % (5/14) of the lesions had grade 2 (25–75 %) fat signal and 29 % (4/14) of the lesions demonstrated grade 0 (0 %) or grade 1 (<25 %) fat signal. 43 % (6/14) of lesions demonstrated homogenous fat suppression, 28 % (4/14) showed focal areas of high internal signal, and 28 % (4/14) had diffuse internal high signal on fluid-sensitive fat-saturated sequences. 86 % (6/7) of the cases demonstrated septal/nodular enhancement. The diagnosis was evident on the CNB specimen in 100 % (9/9) cases. The histopathology fat content grade was in agreement with the imaging grade in 86 % (12/14) cases.

Conclusions

The internal signal pattern of SCL can range broadly, with low fat content lesions seen almost as commonly as intermediate and high fat content lesions. We also found that the fat:non-fat internal MR signal pattern of these lesions is accurately reflected in their composition at histology.     

肾上腺残基瘤的MR成像特征

目的 探讨肾上腺残基瘤的影像特征.方法 回顾性分析经手术病理或临床确诊的12例肾上腺残基瘤患者资料,12例均行超声检查,11例行MR平扫加增强扫描,1例行CT平扫加增强扫描,总结该病的影像表现特点.结果 12例患者中,肿瘤发生在睾丸10例,发生在卵巢和阔韧带2例.睾丸肾上腺残基瘤影像表现:双侧睾丸对称性发病,睾丸外形无改变,睾丸内出现肿块.超声表现以低回声为主,内可有条状强回声,彩色多普勒超声示内有丰富血流信号;CT平扫病变呈等密度,增强扫描示睾丸内肿块明显强化;MR显示肿块大小0.7 cm × 1.0 cm×2.2 cm～2.3 cm×2.7 cm×2.9 cm,信号均匀,边界清楚且略呈分叶状,T1WI呈等或稍高信号,T2WI呈稍低信号,增强扫描肿块明显强化.2例卵巢和阔韧带残基瘤彩色超声和MR均未发现异常.结论 影像表现结合典型的临床病史,可在术前诊断肾上腺残基瘤.     

静脉性脑梗死MR影像特点

目的回顾总结静脉性脑梗死MRI及MRV影像表现,旨在提高影像诊断水平。方法对15例静脉性脑梗死的MR表现进行了回顾性分析,其中9例临床治疗后复查MR表现明显好转,临床症状明显改善。15例均行常规MRI平扫,其中9例同时进行MR增强及3DCE-MRV,6例行2DTOF MRV。结果 15例脑内多发病灶9例,单发病灶6例,其中2例脑梗死伴出血改变。15例中发生于额叶4例,顶叶6例,颞叶3例,枕叶1例,小脑1例。静脉栓塞部位11例为上矢状窦,1例直窦及左横窦,1例右侧横窦及乙状窦,2例皮层大脑浅静脉。9例行增强扫描,5例病灶内不规则强化,2例脑膜强化,3例无强化.7例MRV均显示栓塞的静脉血流信号丢失或缺损,3例出现异常静脉侧支或引流静脉异常扩张。结论静脉性脑梗死MR影像表现具有特征性,MRI结合MRV可以作为首选的无创检查方法,对静脉栓塞早期诊断和治疗有重要作用。     

Arachnoiditis ossificans: MR imaging features in five patients.

OBJECTIVE: The purpose of this article is to illustrate the appearance of arachnoiditis ossificans on MR imaging and discuss the implications this diagnosis has on treatment. CONCLUSION: In patients with arachnoiditis ossificans, the MR imaging findings are of linear or masslike intrathecal lesions, which generally have some hyperintensity on T1- weighted sequences and are hyper- or hypointense on T2-weighted images, in the setting of arachnoiditis.     

MR imaging of liposarcomas: correlation of MR features and histology

The magnetic resonance (MR) imaging features of liposarcoma were correlated with histology in 15 patients. The MR findings for liposarcoma were not specific. The six myxoid liposarcomas and two atypical lipomatous tumors, however, had distinctive MR features, i.e., nodular masses of slightly heterogeneous intermediate to high signal intensity (SI), intermingled with high SI septa on T1-weighted images. The T2-weighted images demonstrated the relative reversal of these regional SI characteristics. Additionally, MR correctly identified the presence of fat in all eight cases in which it was pathologically present. The fat in two atypical lipomatous tumors was inseparable on MR from the subcutaneous fat. Magnetic resonance appears useful for preoperative staging and follow-up studies of liposarcomas. It may be helpful in identifying patients with myxoid liposarcoma and atypical lipomatous tumors who have longer survival times.