周围软组织血管瘤和血管畸形MRI鉴别诊断

目的探讨血管瘤和血管畸形MRI的鉴别诊断。方法回顾性分析61例手术证实的血管瘤和血管畸形MRI表现并与病理进行对照。结果29例血管瘤中,在T1WI上,20例为等信号(等于肌肉信号),9例为高等混杂信号;在T2WI上,24例呈较高信号(接近脂肪信号),5例呈高信号(高于脂肪信号),另见25例条状低信号分隔,其中4例增强呈分块状强化。32例血管畸形中,T1WI图,16例为等信号,16例为高等混杂信号;T2WI图,3例呈较高信号,29例呈高信号。其中15例增强呈不均匀强化。结论MRI对血管瘤和血管畸形的鉴别诊断有重要价值。     

Fibroma of tendon sheath of the infrapatellar fat pad in the knee

A 69-year-old patient with unexplained pain of the right knee reported no prior trauma. A soft tissue tumor was identified using magnetic resonance imaging (MRI). The tumor showed low signal intensity on T1-weighted images, high signal intensity on T2, and peripheral enhancement on gadolinium-enhanced MRI. Perioperative observation revealed that the tumor was partly adhesive to the anterior knee joint capsule, but not to the patellar tendon.     

星形细胞肿瘤ADC与细胞密度导航导引下的对照研究

目的:分析脑肿瘤的ADC及细胞密度,评价肿瘤组织ADC值与细胞密度的相关性及ADC值在评价肿瘤良恶性中的价值.材料和方法:10例脑肿瘤病例术前行DWI及导航序列扫描,在导航手术中切除肿瘤时,同时在导航仪图像上标记相应肿瘤组织的部位,标本送病理检查.采用NIH Image软件分析肿瘤组织细胞密度.在导航标记图的指导下测量相应部位的ADC值及T2信号强度,比较ADC值,T2信号强度与细胞密度的相关性及其在评价肿瘤良、恶性中的作用.结果:10例脑肿瘤中毛细胞型星形细胞瘤1例,星形细胞瘤3例,间变性星形细胞瘤1例,胶质母细胞瘤5例.ADC值与肿瘤细胞密度呈明显负相关,r=0.74,P＜0.001,T2信号强度与细胞密度仅有轻度相关,r=0.33,P＜0.05.WHO1～2级肿瘤的ADC值1.30±0.16×10-3mm2/s,T2信号强度1374±336;3～4级肿瘤ADC值0.90±0.16×10-3mm2/s,T2信号强度1110±171,良、恶性肿瘤各种参数之间两组比较均有显著性差异(P＜0.01).结论:ADC是评价星形细胞肿瘤细胞密度的一个有效手段.ADC值低的部位可能是肿瘤细胞密度高的部位,也就可能是恶性程度最高的部位,对于立体定向选择活检部位非常有效.良、恶性星形细胞肿瘤ADC值有明显差异,结合常规MRI,ADC值可用于推测脑肿瘤的良、恶性.     

MRI of tuberculous pyomyositis.

PURPOSE: The purpose of this article is to describe the findings of MRI in tuberculous pyomyositis (PM). METHOD: The MR images of four proven cases of tuberculous PM were retrospectively reviewed and analyzed with clinical and laboratory findings. The location, signal intensity on T1- and T2-weighted spin echo images, presence of abscess, signal intensity of peripheral rim, patterns of contrast enhancement, and associated findings were evaluated. RESULTS: On MR images, all cases demonstrated low signal intensity on T1-weighted images and high signal intensity on T2-weighted images in a single muscle. Abscess was seen in all cases. Peripheral rim showed subtle hyperintensity on T1-weighted images and hypointensity on T2-weighted images. After gadolinium infusion, peripheral rim enhancement was observed in all cases. Cellulitis was associated in one case. The patients clinically presented with a palpable mass of long duration. CONCLUSION: Tuberculous PM shows characteristic findings of a well demarcated abscess with rim enhancement at MRI and can be distinguished from other soft tissue masses.     

Gossypiboma in abdomen and pelvis: MRI findings in four patients

OBJECTIVE: The purpose of our study was to describe the MRI features of gossypiboma and correlate the MRI findings with the pathologic findings in four patients. CONCLUSION: On MRI, gossypiboma in the abdomen and pelvis manifested as a well-defined mass that showed a peripheral wall of low signal intensity at T1- and T2-weighted imaging and enhancement at contrast-enhanced T1-weighted imaging. The whorled stripes within the central portion were characteristically shown as low signal at T2-weighted imaging, and the serrated contour in the inner border of the peripheral wall was shown at contrast-enhanced T1-weighted imaging. Histopathologically, the peripheral wall showed granulomatous inflammation with massive fibrosis and foam cell and multinucleated giant cell infiltrations, whereas the whorled stripes within the central portion were gauze fibers. If a patient has a history of a previous operation, the possibility of gossypiboma should be suggested when the central whorled stripes or serrated contour in the inner border of the peripheral wall is present at MRI.     

Odontogenic myxoma of maxillary sinus: CT and MR-pathologic correlation

We showed the characteristic features of odontogenic myxoma in the maxillary sinus with computed tomography (CT), magnetic resonance imaging (MRI), and histopathological findings. CT images showed a multilocular soft tissue mass with bone destruction and thinning, and the characteristic finding of this lesion as strands of fine lacelike density. MRI revealed intermediate signal intensity on T1-weighted image and high signal intensity on T2-weighted image. MRI showed the erosive extent of the lesion into the adjacent structures. In contrast T1-weighted image, the peripheral portion of the lesion with a relatively large quantity of collagen bundles was enhanced, while the central portion with only mucoid component was not. The CT and MRI appearances correlated well with the histologic features and therefore were considered to be a useful tool for diagnosis of myxoma.     

Atypical appearance of elastofibroma dorsi on MRI: case reports and review of the literature

Three patients with histologically proven elastofibroma dorsi underwent MRI, using T1-weighted, T2-weighted, STIR (short inversion time inversion recovery), and contrast-enhanced SE sequences. All lesions typically displayed low signal intensity masses interspersed with areas of high signal intensity on T1- and T2-weighted SE images. Contrary to prior reports, two patients showed marked enhancement of the mass after administration of Gd-DTPA. Although the characteristic signal intensity on conventional T1- and T2-weighted images may lead to the early diagnosis of this rare tumor, radiologists should be aware that marked contrast enhancement may be representative in elastofibroma dorsi.     

Usefulness of diffusion-weighted MRI with echo-planar technique in the evaluation of cellularity in gliomas

The purpose of this study was to evaluate the utility of diffusion-weighted magnetic resonance imaging (MRI) with echo-planar imaging (EPI) technique in depicting the tumor cellularity and grading of gliomas. Twenty consecutive patients (13 men and 7 women, ranging in age from 13 to 69 years) with histologically proven gliomas were examined using a 1.5 T superconducting imager. Tumor cellularity, analyzed with National Institutes of Health Image 1.60 software on a Macintosh computer, was compared with the minimum apparent diffusion coefficient (ADC) and the signal intensity on the T2-weighted images. The relationship of the minimum ADC to the tumor grade was also evaluated. Tumor cellularity correlated well with the minimum ADC value of the gliomas (P = 0.007), but not with the signal intensity on the T2-weighted images. The minimum ADC of the high-grade gliomas was significantly higher than that of the low-grade gliomas. Diffusion-weighted MRI with EPI is a useful technique for assessing the tumor cellularity and grading of gliomas. This information is not obtained with conventional MRI and is useful for the diagnosis and characterization of gliomas.     

CT and MR imaging of desmoplastic fibroblastoma

Desmoplastic fibroblastoma (collagenous fibroma) developing as a slowly enlarging lower abdominal mass is described. The lesion had inhomogeneous low signal intensity (SI) on T1-weighted images, and mixed SI as low SI within high SI on T2-weighted images. On post-contrast T1-weighted images, the mass showed inhomogeneous enhancement. Histologically, the areas showing low SI on both post-contrast T1- and T2-weighted images consisted of dense collagenous components and reduced cellularity compared with the areas showing high SI on them.     

Magnetic resonance imaging of myositis ossificans: analysis of seven cases

Myositis ossificans typically presents as soft tissue swelling with progressive ossification on radiographs. Since magnetic resonance imaging (MRI) is commonly used to evaluate soft tissue masses, we analyzed eight MR examinations in seven patients with myositis ossificans to determine if typical patterns were present. One acute lesion had homogeneous intermediate signal intensity on T1-weighted images and high signal intensity on T2-weighted images. Two subacute lesions had low signal intensity margins with slightly increased signal intensity centers on T1-weighted images and very high signal intensity on T2-weighted images. Five chronic lesions had two different patterns. All five were well-defined with low signal intensity borders. Three had signal intensity patterns characteristic of fat on T1-weighted and T2-weighted images. The other two lesions had intermediate signal intensity on T1-weighted images and slightly increased signal intensity on T2-weighted images.We conclude that typical MR appearances of myositis ossificans do exist. A low signal intensity rim is a common finding. However, these patterns are not unique to myositis ossificans and resemble those that have been reported in other lesions. It is important to be aware of the spectrum of MR findings of myositis ossificans when considering the differential diagnosis of a soft tissue mass.     

Subungual keratoacanthoma: ultrasound and magnetic resonance imaging findings

Subungual keratoacanthoma is a rare, squamoproliferative neoplasm arising at the nail bed. It may cause erosion of the underlying bone. We report a case of subungual keratoacanthoma of the right thumb in a 63-year-old man. Radiographs showed cortical erosion of the distal phalanx of the right thumb. Ultrasonography showed a mixed echoic tumor. On magnetic resonance imaging (MRI), the tumor showed intermediate signal intensity on T1-weighted images and mixed intermediate and high signal intensity on T2-weighted images with peripheral thin rim enhancement.     

Characteristic MR findings of cervical pregnancy

The aim of this study was to define the characteristic MR findings of cervical pregnancy. Twelve patients with cervical pregnancy underwent MRI because of difficulty in the diagnosis by ultrasonography, human chorionic gonadotropin assessment, and other clinical evaluations. The assessment of MRI included size and location of the lesion, margin, MR signal intensity, rim of low-signal intensity, enhancement pattern, appearance of enhancing solid component, parametrial change, endometrial change, pelvic fluid collection, and ovarian change. All cases showed ill-marginated mass with very heterogeneous signal intensity on T2-weighted images, irregular internal high-signal intensities on T1-weighted images, a partial or circumferential rim of low-signal intensity, dense irregular peripheral enhancement and enhancing papillary solid components with accompanying tubular signal voids, and variably increased parametrial vascularities. This heterogeneous hemorrhagic mass with densely enhancing papillary solid components may be the typical MR finding for cervical pregnancy. J. Magn. Reson. Imaging 2001;13:918-922.     

Germinoma originating in the basal ganglia

A case of germinoma originating in the basal ganglia is presented. Preoperative MRI showed an area of a reticulated core of mixed signal intensity with a surrounding rim of low signal intensity in the right basal ganglia on T2-weighted image. This finding was reported to be characteristic of cavernous angioma, but the tumor was histopathologically identified to be a germinoma with old hemorrhage. The pitfall of MRI in diagnosing brain tumors is discussed.     

MRI of testicular epidermoid cyst

This report presents and discusses the magnetic resonance imaging (MRI) and pathological findings of a case of testicular epidermoid cyst. A 35-year old man consulted a physician after he felt an enlargement of the right testis. Physical examination revealed a painless, non-tender, elastic hard mass in the right testis. A radiological examination was performed. MRI demonstrated an enlarged right testis, with a mass in it. The mass showed slightly low signal intensity on T1-weighted imaging, and high signal intensity on T2-weighted imaging. Both the T1- and T2-weighted images revealed a peripheral low signal intensity rim. The mass showed no enhancement. A right orchiectomy was carried out for epidermoid cyst. Pathologic examination showed a well-encapsulated nodule within the right testicular parenchyma, filled with a cheesy, yellow-white material similar in appearance to atheroma. The bull's-eye appearance is considered to depend on the presence of calcification. From the viewpoint of pathology, testicular epidermoid cysts do not always show bull's-eye. We then must recognize that some testicular tumors may be epidermoid cysts even without the bull's-eye findings.     

Sclerosing perineurioma: tumor of the hand with a short T2

We present two cases of sclerosing perineurioma, a rare soft tissue tumor, in the palm and the ring finger respectively, presenting as a small, painless and subcutaneous mass. This tumor has a predilection for the digits and palms of young, predominantly male adults. In the present cases the tumors showed very low signal intensity on T2-weighted magnetic resonance (MR) images. Histologically they contained abundant collagen and hyalinized stroma, which would account for areas of low signal intensity on T2-weighted MR images. Immunohistochemically, the tumor cells were positive for vimentin, epithelial membrane antigen and human erythrocyte glucose transporter 1 and negative for S-100 protein. To the best of our knowledge, the appearance of sclerosing perineurioma on MR imaging has not been previously reported in the English-language literature. Sclerosing perineurioma should be considered in the differential diagnosis of hand tumors when the tumor shows low signal intensity on T2-weighted MR images.     

Infantile myofibromatosis: review of imaging findings and emphasis on correlation between MRI and histopathological findings

BackgroundInfantile myofibromatosis (IM) is the most common fibrous tumor of infancy. MRI is considered the gold standard in IM evaluation. Very little has been published about IM with histopathology correlation in the pediatric age.PurposeDescribe imaging findings in IM and correlate MRI findings with histopathology.Material and methodsImaging findings of 17 patients with IM were retrospectively analyzed including CT, US and MRI. Signal characteristics on T1-, T2-weighted and STIR imaging, extent of T2-hyperintensity, degree & pattern of enhancement, diffusion restriction, location & margins, & involvement of adjacent structures were tabulated. Histopathology findings included cellularity, collagenization, myxoid changes, atypia, mitosis & microscopic invasion. Established grading scores were utilized.ResultsRelative to normal skeletal muscle, on T1-weighted imaging, 9 lesions had similar signal while the remaining had a mixture of iso & hypo intensity; whereas on T2-weighted and STIR imaging, all 12 lesions demonstrated a mixture of iso, hypo & hyperintensity. T2-hyperintensity was grade 2 in one, grade 3 in 8 & grade 4 in 3 lesions. Intensity of enhancement was grade 2 in one, grade 3 in 8 & grade 4 in 3 lesions. Enhancement was predominantly peripheral in all 12 lesions.Extent of T2-hyperintensity & degree of enhancement corresponded to variable grades on histopathology.CT and US showed nonspecific findings.ConclusionOn MRI, IM has a mixture of signal intensity with predominant hyperintense signal on T2W images. However various signal & enhancement features correlated poorly with specific histopathologic grades.     

Extent and time course of morphological changes of bone marrow induced by granulocyte-colony stimulating factor as assessed by magnetic resonance imaging of healthy blood stem cell donors

The aim of this study was to assess the time course and extent of signal alterations of red bone marrow after short-term stimulation by recombinant human granulocyte-colony stimulating factor (rHuG-CSF) in healthy peripheral blood stem cell donors using magnetic resonance imaging (MRI) at low-field strength. Twelve healthy blood stem cell donors without evidence of bone marrow disorders were prospectively investigated and underwent four MRI studies of their lumbar spine. Sagittal T1- and T2-weighted spin-echo sequences and a gradient-echo (GE) sequence with an echo time for out-of-phase imaging were performed prior to rHuG-CSF application (baseline MRI), on the day of first stem cell harvest (after 70 microg/kg body weight rHuG-CSF, second MRI) followed by two studies 9-18 days (median 14.5 days, third MRI) and 26-48 days (median 39.5 days, fourth MRI) after discontinuation of rHuG-CSF application. Baseline MRI showed normal marrow signal in all patients. The second MRI revealed a decrease of quantified bone marrow signal relative to nucleus pulposus in T1- and T2-weighted images and an increase of relative signal in out-of-phase GE sequences. The greatest changes of relative marrow signal were observed at the third MRI. Compared to baseline MRI, relative marrow signal was diminished by 12% in T1-weighted images and increased by 59% in GE sequences, consistent with a rise in marrow cellularity simulating diffuse marrow disease. At the fourth MRI quantified relative marrow signal returned to baseline levels in all sequences. In healthy individuals rHuG-CSF application leads to significant signal changes of bone marrow in lumbar vertebra that are maximal about 2 weeks after discontinuation of rHuG-CSF application. In patients with underlying marrow disorders who receive hematopoietic growth factors during treatment, these changes should not be confused with disease progression.     

Solitary fibrous tumor of the pleura: MR appearance and enhancement pattern

PURPOSE: The aim of the current study was to characterize the MR appearance of solitary fibrous tumor of the pleura (SFTP). METHOD: Twenty-two consecutive patients with histologically confirmed SFTP were retrospectively evaluated with MRI. RESULTS: Tumors demonstrated low signal intensity (n = 18, 82%), iso signal intensity (n = 2, 9%), and high signal intensity (n = 2, 9%) on T1-weighted images. On T2-weighted images, tumors were observed as low signal intensity (n = 10, 45%), high signal intensity (n = 2, 9%), and mixed signal intensity (n = 10, 45%). Solid component in the proliferation of tumor cells corresponded to low signal intensity in 12 tumors (55%) on T2-weighted images. On gadolinium-enhanced T1-weighted images, inhomogeneous enhancement (n = 18, 82%), nodular enhancement (n = 6, 27%), and homogeneous enhancement (n = 4, 18%) were observed. The enhanced lesion within the tumors had dense tumor tissue and dilated microvessels in the pathologic specimen. CONCLUSION: SFTP shows variable appearance and enhancement pattern on MRI according to morphologic tumor heterogeneity.     

Angiomyolipoma arising in the thigh

A 41-year-old man presented with an asymptomatic mass in the right medial thigh. Magnetic resonance imaging (MRI) revealed a well-demarcated, 10-cm mass in the right adductor muscles. The margins of the mass exhibited high signal intensity and the rest showed low or iso signal intensity on T1-weighted MR images. However, the high signal intensity was decreased on T2-weighted images with fat suppression. The central part of the tumor was of inhomogeneous high signal intensity on T2-weighted images; after Gd-DTPA injection it enhanced inhomogeneously on T1-weighted images with fat suppression. On dynamic computed tomography (CT) in the arterial phase, there were strongly enhancing spotty areas in the tumor. At surgery, a yellow-whitish tumor was resected and a pathological diagnosis of angiomyolipoma (AML) in the thigh was made. Received: 21 June 1999 Revision requested: 28 July 1999 Revision received: 13 December 1999 Accepted: 15 December 1999     

Intraosseous epidermal cyst of the distal phalanx of the thumb: radiographic and magnetic resonance imaging findings

We report conventional radiographic and magnetic resonance imaging (MRI) findings of an intraosseous epidermal cyst of the distal phalanx of the right thumb in a 39-year-old man. Conventional radiographs showed a sharply well-circumscribed osteolytic lesion of the distal phalanx with interruption of its tip. The osteolytic lesion itself showed low signal intensity on T1-weighted images and high signal intensity on T2-weighted images without contrast enhancement. However, the soft tissues surrounding the osteolytic lesion demonstrated contrast enhancement on MRI. The combined conventional radiographic and MRI findings suggested the diagnosis of intraosseous epidermal cyst rather than enchondroma, giant cell tumor, intraosseous glomus tumor, aneurysmal bone cyst, or simple bone cyst.