MR imaging of pericallosal lipoma

Early pathologic reports of corpus callosal lipoma described a consistent relationship between the lipoma and the dorsal surface of the corpus callosum, particularly when the lipoma is not associated with corpus callosal agenesis. MR imaging, especially T1-weighted sagittal acquisitions, exquisitely demonstrated this anatomic relationship in three relatively asymptomatic patients. Therefore, in most cases, a lipoma of the corpus callosum is more accurately described as a pericallosal lipoma. In one individual, common associated findings (partial agenesis of the corpus callosum and choroid plexus lipoma) were also noted. Surgical therapy is usually not indicated because symptoms are generally not related and the anterior cerebral artery is often encased by the lipoma.     

MR imaging of a parosteal lipoma

A case of a parosteal lipoma of the thigh is presented. Very little is known of the enhancement features of this tumor. In this case, mild enhancement of tissue in the region of the pedicle between reactive cortical bone hyperostosis and the lipomatous mass corresponded to fibrous tissue that outlined the hyperostotic reactive bone.     

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.     

CT and MR imaging characteristics of intravestibular lipoma

BACKGROUND AND PURPOSE: Intracranial lipomas are uncommon congenital malformations that most often are asymptomatic. A rare subset of intracranial lipomas arises within the vestibule of the inner ear, which can cause sensorineural hearing loss. We present the CT and MR imaging characteristics of lipomas within the vestibule of the inner ear and propose a pathogenetic mechanism for this malformation. METHODS: We retrospectively reviewed five cases of vestibular lipoma. T1-weighted axial conventional spin-echo and T2-weighted axial fast spin-echo sequences were performed in all five cases. Four patients underwent T1-weighted fat-saturated imaging, and one underwent CT scanning with Hounsfield units measured. RESULTS: Four female patients ranging in age from 10 to 40 years and one 26-year-old male patient had sensorineural hearing loss. Two patients had progressive high-frequency loss; one, sudden-onset high-frequency loss; and two, congenital high-frequency loss. All had lesions within the vestibule that displayed hyperintensity on T1-weighted images, isointensity to slight hypointensity on T2-weighted fast spin-echo images, hypointensity with fat saturation, and fat attenuation on CT scans. Three of the cases were associated with lipoma of the cerebellopontine angle. In none of these cases were the cerebellopontine angle and labyrinthine lipomas contiguous. CONCLUSION: Intravestibular lipoma is considered when a focal hyperintense lesion is identified within the vestibule of the inner ear on T1-weighted MR images. Lesion hypointensity on fat-saturated T1-weighted MR images verifies its lipomatous nature and separates it from intralabyrinthine hemorrhage or highly proteinaceous fluid.     

MR imaging of lipoma arborescens and the associated lesions

Objective To describe the typical features of lipoma arborescens on MR imaging with pathologic correlation and to evaluate the associated lesions within the joints.Design and patients The MR imaging findings of 32 patients with the diagnosis of lipoma arborescens of the knee (n=32) and shoulder (n=1) were reviewed. The diagnosis of lipoma arborescens was confirmed by the histologic findings in 12 cases and the other 21 cases were diagnosed by the characteristic MR imaging features. One patient had bilateral lipoma arborescens of the knee joint.Results MR imaging showed a typical pattern of villous lipomatous proliferation of the synovium in all cases, as a diffuse pattern in 79% (26/33) of cases and as a dominant mass-like lesion in 21% (7/33) of cases. The associated MR pathology in the knee was (n=32): joint effusion (100%), degenerative changes (87%), meniscal tear (72%), synovial cysts (38%), bone erosions (25%), chondromatosis (13%), patellar subluxation (6%) and discoid meniscus (3%). In all cases except two there was associated pathology of the knee. MR imaging showed an associated rotator cuff tear in the lipoma arborescens of the shoulder.Conclusion The characteristic MR features of lipoma arborescens allows an accurate diagnosis of this rare lesion, which is almost always associated with other chronic pathology of the joint in the elderly.     

Giant infiltrating lipoma of the face: CT and MR imaging findings

Infiltrating lipoma is an uncommon mesenchymal neoplasm that characteristically infiltrates adjacent tissues and tends to recur after excision. This type of lipoma is extremely rare in the head and neck region. We report a case of a giant infiltrating lipoma of the face, studied with CT and MR imaging.     

Septum-like structures in lipoma and liposarcoma: MR imaging and pathologic correlation

 Objective. To investigate the septum-like structures in predominantly lipomatous tumors, by correlating fat-suppressed MR images with histopathologic findings. Design and patients. The MR findings of three cases of well-differentiated liposarcoma (atypical lipoma), one case of lipoma-like component of dedifferentiated liposarcoma, and nine cases of lipoma were analyzed. T1-, T2-, and fat-suppressed T1-weighted images after Gd-DTPA administration were obtained. Surgical specimens from five patients (four with liposarcoma and one with lipoma) were also scanned with a MR unit, and compared with the pathologic findings. Results and conclusions. Enhancement features of lipoma and liposarcoma were well visualized on fat-suppressed T1-weighted images after Gd-DTPA administration. The septum-like structures of liposarcoma are thick and enhanced considerably, while septa of lipoma are thin and enhanced only slightly. Pathologically, the septum-like structures of liposarcoma contained muscle fibers and the septa of lipoma represented fibrous capsule. Identification of well-enhanced septa in a predominantly lipomatous tumor helps to differentiate malignant tumors from lipomas. As the septum-like structures of liposarcoma contain a skeletal muscle component the tumor might need more extensive surgical procedures including resection of adjacent muscles.     

Case report: lipoma of the liver--ultrasound, CT and MR imaging.

A case of lipoma of the liver is presented; ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) findings are reviewed and compared with previous reports. The ultrasound pattern and appearance of the tumour in CT as well as MRI are discussed.     

MRI在结肠癌诊断中的应用研究

目的 探讨结肠癌的MRI表现和诊断价值，作出正确的临床分期和可切除性评估。方法 40例结肠癌患者，空腹12h，检查当天行清洁灌肠或当晚服用番泻叶浸液，检查前10min肌内注射山莨菪碱10mg，检查前即刻由肛门注入生理盐水800～1000ml，行多方位、多序列MR增强前后扫描以资对照：32例手术患者，术前进行Dukes分期和可切除性评估，并与病理进行对照。结果受检的40例患者可清晰显示结肠，特别是直肠和乙状结肠的解剖结构、邻近器官的毗邻关系。结肠癌T1WI呈中等信号，T2WI呈等或高信号，脂肪抑制(SPlR)序列呈高信号；增强后35例(87.5％)有明显强化；8例(20．0％)有邻近脏器受累，MRI显示6例；淋巴结转移12例，MR显示8例。术前评估32例可切除，8例不可切除，术后4例高估，术前切除评估符合率87．5％；MRI对结肠癌的诊断符合率为100．0％。结论 MRI可清晰显示结肠的肠壁厚度、解剖结构和毗邻关系。在结肠癌诊断中不仅能显示肠壁肿块、厚度、邻近器官的侵犯，还能显示淋巴结肿大及盆腹腔转移，其信号改变颇具特异性；在病变的诊断、分期和可切除性评估等方面具有较高的临床应用价值。     

Spindle cell lipoma of the head and neck: CT and MR imaging findings

Introduction

Spindle cell lipoma (SCL) is an uncommon benign lipomatous tumor, most commonly occurring in the posterior neck and shoulder. The purpose of this study was to investigate the CT and MR imaging features of SCL in the head and neck.

Methods

CT (n?=?5) and MR (n?=?3) images of seven patients (five men and two women; mean age, 54 years) with surgically proven SCL in the head and neck were retrospectively reviewed. The location and morphologic characteristics of SCL were documented as well.

Results

Six lesions were well-defined and located in the subcutaneous fat of the posterior neck (n?=?4), anterior neck (n?=?1), and buccal space (n?=?1). One lesion was ill-defined and located deeply in the supraclavicular fossa, infiltrating the adjacent shoulder muscles. Intratumoral fat was identified in five lesions in various amounts. Compared with the adjacent subcutaneous fat, intratumoral fat was slightly hyperattenuated on CT scans and slightly hypointense on T1-weighted MR images. In five of six lesions in which postcontrast CT and/or MR images were obtained, significant enhancement was seen in the nonadipose component of the lesion.

Conclusion

Various components of the adipose and nonadipose tissues may cause difficulty differentiating between SCL and other adipocytic tumors including liposarcoma radiologically. Although nonspecific, the radiologist should know the various imaging features of SCL, because the tumor can be cured by simple excision.     

Diagnosis of a colonic lipoma with computer tomography

This report describes the case history of a woman with a large submucosal tumor in the ascending colon detected by barium enema radiography. Computed tomography (CT) identified the tumor as a submucosal lipoma characterised by its homogeneous fat-equivalent density with a CT number of -95 HU. This case proves that CT can be a definite diagnostic modality for differentiation between gastrointestinal lipomas and other solid or cystic tumors.     

Trigeminal nerve lipoma: MR findings

Trigeminal nerve lipomas are rare tumors that typically cause progressive focal neurologic symptoms due to their intimate involvement with nerve fascicles and adjacent neural structures. We describe the CT and magnetic resonance (MR) findings of this unusual tumor. The changes in signal intensity on T1 and T2 weighted MR scans provide precise anatomic location and tissue characterization prior to surgical intervention.     

Diagnostic imaging of lipoma arborescens

Objective. The imaging characteristics of lipoma arborescens using plain radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) are described. Design and patients. Five patients with a diagnosis of lipoma arborescens are presented. Three had monoarticular involvement of the knee joint. In the remaining two patients both knees and both hips, respectively, were affected. All patients were examined using plain radiographs and MRI. CT was employed in two cases. Results and conclusions. A conclusive diagnosis with exclusion of other synovial pathologies having similar clinical and radiological behaviour can be achieved on the basis of the MRI characteristics of lipoma arborescens. The aetiology of lipoma arborescens remains unknown, but its association with previous pathology of the affected joints in all our patients supports the theory of a non-neoplastic reactive process involving the synovial membrane.     

Pantopaque mimicking spinal lipoma: MR pitfall

We present a patient with an intraspinal, high-signal-intensity lesion in the lumbosacral region on T1-weighted magnetic resonance images and a thin line of signal void between this region and the CSF on T2-weighted images. These findings were interpreted initially as representing an extradural spinal lipoma. However, CT revealed an intrathecal collection of iophendylate (Pantopaque), which was subsequently removed via a lumbar puncture. The apparent separation of Pantopaque from the CSF (seen on T2-weighted images and interpreted as the dura) was probably caused by chemical shift artifact, chemical shift contour, and/or CSF motion artifact.     

MR appearance of intracanalicular eighth nerve lipoma.

The authors present the MR appearance of an intracanalicular eighth nerve lipoma in a 30-year-old woman, describe the clinical manifestations, and discuss the possible etiology; biopsy findings were conclusive. Precontrast T1-weighted images should be obtained.     

胃肠道脂肪瘤的影像学诊断

目的 探讨胃肠道脂肪瘤的影像学特征及诊断价值.方法 回顾性分析经手术病理证实8例(男性3例,女性5例)胃肠道脂肪瘤的影像学表现,其中X线胃肠道造影4例、CT检查8例、MRI检查3例,分别观察肿块的位置、大小、形态、密度、信号、管腔状态、周围粘膜等各种影像学表现,并结合手术、病理对照.结果 ①发病部位:8例胃肠道脂肪瘤位于胃、十二指肠、回肠、结肠分别为1、1、1、5例;7例为胃肠道腔内肿块,起源于粘膜下层;1例升结肠脂肪瘤表现为肠腔内、外肿块,起源于浆膜下层;②影像学特征:表现为胃肠道内大小不等类圆形、卵圆形肿块,柔软,边缘清楚,4例X线消化道气钡双重造影及结肠气钡双重造影显示为类圆形的充盈缺损,4例周围均可见桥形粘膜;CT显示为密度均匀的脂肪密度肿块,CT值在-70～-120HU之间,增强扫描肿块无明显强化,1例发生在降结肠继发坏死,表现为瘤体内合并液性低密度;MRI肿块在T1WI、T2 WI呈高信号,T2抑脂像为低信号.结论 胃肠道脂肪瘤的影像学表现典型,肿块柔软、桥形粘膜、脂肪密度、高信号等为其特征表现,术前CT、MRI准确诊断率高.     

Intraosseous lipoma of the humeral head: MR appearance

Intraosseous lipoma is the rarest benign primary bone tumor. We report a case of juxtaarticular intraosseous lipoma in the humeral head of a 50-year-old man. Roentgenographic, computed tomographic (CT), magnetic resonance (MR), scintigraphic, and histologic findings of this case are presented.