动脉瘤样骨囊肿的影像学特点及介入技术在其诊疗中的意义

目的探讨动脉瘤样骨囊肿(ABC)的影像学特点及介入法动脉栓塞对该病的临床应用价值。方法回顾性分析18例经手术病理证实的原发性ABC的影像学征象,其中10例曾于术前进行动脉栓塞治疗。结果ABC的X线平片常呈偏心性膨胀性骨破坏;在CT成像中,10例可见液平面,8例出现钙化或骨化;MRI成像表现为分隔状囊性病变区,在T1加权像为不均匀中高信号,在T2加权像数个呈高信号囊腔及低信号的间隔影,12例出现液平面。结论动脉瘤具有一定的影像学特点,介入法是一种有价值的术前辅助性治疗方法。     

Epithelioid hemangioma of bone

Epithelioid hemangioma of bone is a rare type of angiomatous tumor. We report a documented case of epithelioid hemangioma occurring in the distal femur of a 35-year-old man. The clinical, radiographic, MR imaging and histologic findings of the tumor are described. Radiographs showed a well-defined expanding, osteolytic lesion in the diaphysis of the femur. MR imaging showed the lesion to have low signal intensity on T1-weighted images and intermediate signal intensity on T2-weighted images. Grossly the lesion was multiloculated with a dark brown, jelly-like content. To characterize the imaging appearances of epithelioid hemangioma, we reviewed the available literature on the subject. Received: 14 February 2000 Revision requested: 28 March 2000 Revision received: 31 May 2000 Accepted: 1 June 2000     

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.     

Synovial sarcoma of primary bone origin: a rare case in a rare site with atypical features

Synovial sarcoma of bone origin is extremely rare and difficult to diagnose. We present a case in which the lesion arose in the cortex of the distal tibia. It showed heterogeneous intermediate signal intensity on T1-weighted images and heterogeneous intermediate to low signal intensity on T2-weighted images with heterogeneous contrast enhancement on MRI. The lesion was confirmed as synovial sarcoma using a combination of histological and molecular genetic studies.     

Primary pleomorphic liposarcoma of bone: MRI findings and review of the literature

Primary liposarcoma of bone is exceedingly rare. We report a case of primary pleomorphic liposarcoma in the humerus of a 38-year-old female. Radiographs demonstrated an expansile and osteolytic lesion extending from the head to the proximal part of the shaft in the right humerus. MR study showed a defined lesion in the humerus. The lesion had an iso-signal intensity and partial high-intensity lesion on T1-weighted images and a heterogeneous high signal intensity on T2-weighted images. Wide resection and proximal humeral endoprosthesis replacement were performed. Final pathological diagnosis of the lesion was pleomorphic liposarcoma. This is the second reported case of pleomorphic liposarcoma of the bone, and the first case presenting MRI findings for liposarcoma of bone.     

Low-field-strength MR imaging of failed hip arthroplasty: association of femoral periprosthetic signal intensity with radiographic, surgical, and pathologic findings

PURPOSE: To investigate the association between periprosthetic signal intensity at low-field-strength magnetic resonance (MR) imaging after failed hip arthroplasty and radiographic, surgical, and pathologic findings. MATERIALS AND METHODS: The study group comprised 22 consecutive women who underwent hip arthroplasty (mean age, 62 years; age range, 35-74 years). All patients underwent MR imaging prior to revision surgery. Coronal fast short inversion time inversion-recovery (STIR) images and spin-echo T1-weighted images were obtained with a 0.5-T MR imaging unit before and after administration of contrast material. The periprosthetic region was divided into the seven femoral Gruen zones. Two observers retrospectively analyzed signal intensity patterns. Association of signal intensity patterns with radiographic, surgical, and pathologic findings was determined with chi2 analysis and generalized estimating equations. RESULTS: Diagnostic-quality images were obtained for 150 zones. Periprosthetic signal intensity was greater than that of bone marrow in the distal femur on the fast STIR images, and no contrast enhancement was seen on the T1-weighted images (type I signal intensity pattern) in 11 zones. Signal intensity was greater than that of bone marrow on the fast STIR images, and contrast enhancement was seen on the T1-weighted images (type II signal intensity pattern) in 45 zones. Signal intensity was less than or equal to that of bone marrow on the fast STIR images, and no contrast enhancement was seen on the T1-weighted images (type III signal intensity pattern) in 94 zones. Type I and II patterns were associated with focal or nonfocal lucency, an unstable stem, and fibrosis or granuloma. A type III pattern was associated with a normal radiographic appearance, a stable stem, and normal bone tissue. Significant association was demonstrated between periprosthetic signal intensity and radiographic (P <.001, chi2 test and generalized estimating equations), surgical (P <.05, Mantel-Haenszel chi2 test and generalized estimating equations), and pathologic findings (P <.05, chi2 test). CONCLUSION: Low-field-strength MR imaging depicted periprosthetic tissue signal intensity that was significantly associated with radiographic, surgical, and pathologic findings.     

Hemangioma of bone arising in the ulna: imaging findings with emphasis on MR

An 18-year-old woman presented with left elbow joint pain. Radiographs and computed tomographic scan showed a well-defined osteolytic lesion of the left ulna associated with a honeycomb appearance on the radiographs. Magnetic resonance images showed intermediate signal intensity on T1-weighted images and mixed intermediate and high signal intensities on T2-weighted images. Only the periphery of the lesion enhanced with intravenously injected gadolinium-diethylenetriamine pentaacetic acid. The lesion was curetted to avoid pathologic fracture, and a histologic diagnosis of cavernous hemangioma of bone was made. Hemangioma involving the ulna is rare, but should be included in the differential diagnosis of a radiographic osteolytic lesion with a honeycomb appearance. Received: 17 September 1999 Revision requested: 31 October 1999 Revision received: 10 December 1999 Accepted: 13 December 1999     

Cross-sectional imaging of primary osseous hemangiopericytoma

The aim of this study was to assess cross-sectional imaging features and the value of CT and MRI in primary hemangiopericytoma of bone. In five patients with histologically proven primary osseous hemangiopericytoma CT and MR scans were evaluated retrospectively. Both CT and MRI were available in four patients each. In three patients both imaging techniques were available. On CT primary hemangiopericytoma of bone presents as an expansive lytic lesion with bone destruction and inhomogeneous contrast enhancement. Magnetic resonance imaging depicts osseous hemangiopericytoma as hyperintense lesion on T2-weighted images with intermediate signal intensity on T1-weighted images. Curvilinear tubular structures of signal void in the tumor matrix on T1-weighted images and corresponding hyperintense structures on T2-weighted and on fat-suppressed short tau inversion recovery images were present in three patients. Although cross-sectional imaging findings are non-specific, they add to the diagnosis and provide valuable information about the extent of bone destruction and local tumor spread in patients with primary osseous hemangiopericytoma. While CT demonstrates the extent of bone destruction best, MRI better visualizes medullary and soft tissue extension of the tumor. Curvilinear signal abnormalities support the diagnosis of hemangiopericytoma of bone. This imaging pattern is best visualized on fat-suppressed or contrast enhanced T1-weighted MR images.     

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.     

Solid aneurysmal bone cyst in the humerus

We report on a 69-year-old woman with a solid variant of aneurysmal bone cyst (solid ABC) in the left humerus with a pathological fracture. Radiographically, the lesion exhibited a relatively well-defined osteolytic lesion in the diaphysis of the left humerus. On magnetic resonance (MR) imaging, the medullary lesion exhibited a homogeneous signal intensity isointense with surrounding normal muscles on the T1-weighted images and a mixture of low and high signal intensity on the T2-weighted images. Contrast-enhanced T1-weighted images revealed diffuse enhancement of the entire lesion. The pathological study showed a proliferation of fibroblasts, histiocytes, chronic inflammatory cells and numerous multinucleated giant cells in a collagenous matrix. Abundant osteoid formation in the matrix was observed, but the cells were devoid of nuclear atypia. Aneurysmal cystic cavities were absent. A review of the English literature found 22 cases of solid ABC of the long bones. Received: 15 February 2000 Revision requested: 18 March 2000 Revision received: 17 April 2000 Accepted: 19 April 2000     

Multimodality imaging features of primary xanthoma of the calcaneus

Secondary xanthomatous features are histologically observed in various bone lesions, but primary xanthoma of bone is rare. We present a primary xanthoma of the right calcaneus in a 51-year-old woman who had no aberrant lipid metabolism. Roentgenograms showed a small osteolytic lesion in the calcaneal triangle, partially surrounded by bone sclerosis. Computed tomographic scans of the calcaneus showed multiple osteolytic areas, with an irregular trabecular pattern in the surrounding sclerotic bone. T1-weighted magnetic resonance images showed a lesion with central low signal intensity, surrounded by a peripheral ring with high signal intensity. The entire lesion showed high signal intensity on T2-weighted images, partially surrounded by areas with low signal intensity, concordant with reactive bone sclerosis. Histologically, the lesion consisted of numerous lipid-laden histiocytes arranged in sheets, scattered multinucleated giant cells and lymphocytes, and granulation tissues. There was no evidence of pre-existing lesions. Total excision of the tumor was curative.     

Juxta-articular hemangioma of long bone

We report on a rare case of an intraosseous hemangioma involving the proximal tibia in a 70-year-old man. Radiographically, the lesion was a well-defined osteolytic lesion with marginal sclerosis. The CT images demonstrated a well-defined osteolytic lesion with partial cortical breakthrough. T1-weighted MR images showed a hypointense lesion, while T2-weighted images revealed hyperintense areas, with internal, hypointense septa. Gadolinium-enhanced T1-weighted images showed lattice-like enhancement of the lesion. Received: 28 December 1999 Revision requested: 3 March 2000 Revision received: 23 May 2000 Accepted: 26 May 2000     

颅骨动脉瘤样骨囊肿的影像学表现

目的：探讨颅骨动脉瘤样骨囊肿的影像学表现，提高对颅骨动脉瘤样骨囊肿的认识。资料与方法：搜集经手术病理证实的4例颅骨动脉瘤样骨囊肿，全部病例均作了CT平扫与MRI检查，其中1例摄有颅骨平片，1例MR／增强扫描，1例DSA检查。结果：4例颅骨动脉瘤样骨囊肿中，1例位于左蝶骨嵴和左眶骨处，2例位于左颞骨。1例位于右额骨。CT上均表现为不同程度的膨胀性吹气球样溶骨破坏区，密度不均匀；MRI示有出血、囊变及液面，T1WI和R2WI上呈混杂信号，1例增强后示肿瘤实质和邻近脑膜强化；血管造影示血管有推移改变。结论：颅骨动脉瘤样骨囊肿的影像学表现有一定的特征性，CT与MRI相结合能提示诊断，并有助于评价周围结构。     

Intradural schwannomas of the spine: MR findings with emphasis on contrast-enhancement characteristics.

Intradural extramedullary schwannomas are nerve sheath neoplasms that consist of focal proliferations of Schwann cells involving a spinal nerve. We reviewed the MR findings in seven patients with pathologically proved intradural schwannomas. The contrast-enhancement characteristics on MR images were determined and compared with the histologic features of the tumor. Six lesions were variably hyperintense on T2-weighted images and one was uniformly hypointense compared with the signal intensity of the spinal cord. Signal on T1-weighted images ranged from hypointense to isointense. All seven tumors showed heterogeneous enhancement; in five, the enhancement involved only the periphery of the lesion. The pattern of enhancement did not correlate with the signal characteristics noted on unenhanced T1- and T2-weighted images. Pathologically, hyaline thickening of vessel walls and cyst formation were prevalent in the peripherally enhancing lesions. However, enhancement did not correlate with the relative proportion of Antoni type A and type B tissue. Recognition of the MR characteristics of intradural extramedullary schwannomas may be helpful in the differential diagnosis of spinal tumors. In particular, peripheral contrast enhancement of an intradural extramedullary tumor on MR images should suggest the diagnosis of schwannoma.     

MR findings of nine cases of palatal tumor.

PURPOSE: To assess the magnetic resonance imaging (MRI) findings of pathologically confirmed palatal tumors. METHODS: Nine cases of palatal tumor were studied. Clinical data, MRI findings, and pathological diagnoses were evaluated. RESULTS: Five cases were tumors of the hard palate and four of the soft palate. Signal intensity on T1-weighted images varied, and hyperintensity was observed on T2-weighted images. Adenoid cystic carcinoma and diffuse large B cell lymphoma showed homogenous signal intensity. Other tumors showed heterogeneous signal intensities. On dynamic contrast analysis, malignant pleomorphic adenoma, adenoid cystic carcinoma, diffuse large B cell lymphoma, and peripheral T cell lymphoma showed early enhancement. On post-contrast T1-weighted images, hard palate pleomorphic adenoma, malignant pleomorphic adenoma, adenoid cystic carcinoma, diffuse large B cell lymphoma, and peripheral T cell lymphoma showed strong enhancement. Although the borders of the tumors were classified as clear in 6 cases treated surgically, macroscopic and microscopic borders of the tumors were unclear. Adenoid cystic carcinoma and hard palate diffuse large B cell lymphoma invaded the maxillary bone. CONCLUSION: Magnetic resonance findings of palatal tumor varied in different histologies. Even with a small palpable portion, malignant tumors could directly infiltrate surrounding structures, which demonstrated well on MRI.     

颅内软骨瘤的CT、MRI诊断

目的总结探讨颅内软骨瘤的CT、MRI特点。方法对1994年1月至2004年9月经手术病理证实的10例颅内软骨瘤的CT、MRI特点进行回顾性分析。结果10例中，肿瘤位于颅底4例，大脑凸面4例，大脑镰区、脑实质内各1例；CT上均见到明显的钙化且边缘清楚，密度多不均匀（9例），相邻骨质可受累（5例）；于MRI上呈混杂信号（4例），其中钙化部分呈长T1、短T2信号，实质部分呈等长T1、长T2信号；CT增强扫描出现轻度强化4例，其中3例为延迟强化。结论颅内软骨瘤好发于颅底、大脑凸面及大脑镰区，多数伴有明显钙化，增强扫描呈轻度强化，延迟强化较有特点。病理仍是主要的确诊手段。     

MR features of aneurysmal bone cyst of the mandible and characteristics distinguishing it from other lesions

Aneurysmal bone cyst (ABC) is a relatively rare, non-neoplastic expansile lesion of bone. Bleeding may occur during an operation or biopsy for ABC, as this cyst is an aneurys with numerous pools of blood. Therefore, it is necessary to diagnose ABC before treatment or biopsy. In the present report, we describe the characteristic computed tomography (CT) and magnetic resonance imaging (MRI) features of ABC in the mandible. Based on the literature and on our own experiences, we compare with the features of ABC with the corresponding features of other lesions showing similar conventional radiographic appearances. In the present case, bone-targeting CT showed the characteristic feature, which reflected the histopathological appearance of a partially cystic meshwork divided by coarse septa. MRI showed almost homogeneous intermediate signal intensity, including a partial slight low-signal-intensity area on the T1-weighted image, and homogeneous high signal intensity, which showed a 'bubbly' appearance, on T2-weighted image. On the enhanced T1-weighted image, the intermediate signal intensity areas apart from the areas that showed slight low-signal intensity on the non-enhanced T1-weighted image, were well enhanced. This creates a 'honeycomb' appearance. The 'meshwork' appearance on bone-targeting CT, the 'bubbly' appearance on the T2WI and the 'honeycomb' appearance on Gd-T1WI may be the characteristic features of ABC.     

Usefulness of opposed-phase gradient-echo technique in the diagnosis of occult lesions of the knee and comparison with traditional T1-weight sequences (in-phase)

PURPOSE: To investigate the usefulness of opposed-phase gradient-echo (GRE) technique in detecting occult posttraumatic bone injuries in the knee. Occult injuries account for pain and, if not properly treated, may progress to severe chondral and bone damage. An early diagnosis provided by MRI can help avoid interventional procedures. MATERIAL AND METHODS: We submitted to MRI of the knee 51 patients (32 men and 19 women) with negative plain radiographic findings and at least one traumatic bone injury at MRI. MR examinations were performed with a 0.5 T unit and included a conventional SE or GRE T1-weighted sequence and an opposed phase GRE sequence on the coronal or sagittal plane (2-3 minutes acquisition). To assess the lesion number and conspicuity, images were retrospectively reviewed by two readers. Injury conspicuity was graded as: 0 (poorly visible), 1 (visible), and 2 (well visible). Marrow-to-injury signal intensity ratio was calculated in 30 patients: a ROI was positioned in the site of highest signal intensity and adjacent bone marrow and the ratio analyzed with Student's "t"-test. RESULTS: In-phase and out-of-phase images showed 71 injuries in 51 patients. Conventional (in-phase) imaging missed 6/71 lesions. Injury conspicuity on out-of-phase images was of grade 2 in 58 cases (81.6%) and of grade 1 in 13 cases (18.3%), versus 23 (32.3%) and 42 (59.1%), respectively, on conventional images. Injury conspicuity was graded as 0 in 6 cases (8.4%) on conventional images. Quantitative analysis of marrow-to-injury signal intensity ratio showed higher values for out-of-phase GRE than conventional images. CONCLUSION: Opposed-phase GRE are quick sequences available on all MR systems which appear superior to conventional T1-weighted images in detecting occult injuries in the knee. Injuries are more conspicuous because their signal intensity is lower due to the simultaneous presence of fat and water protons, which is typical of bone trauma, GRE sequences make a useful and rapid complement to T1-/T2-weighted fat saturation acquisitions in the study of the post-traumatic knee.     

Cross-sectional imaging patterns of desmoplastic fibroma

The aim of this study was to work out the cross-sectional imaging characteristics of desmoplastic fibroma (DF). In 3 patients with histologically proven DF, the imaging characteristics obtained with cross-sectional techniques were reviewed retrospectively. Radiographs and CT scans were available in all patients, and plain and contrast-enhanced MR examinations in 2 patients. Compared with conventional radiographs, CT allowed more accurate assessment of the extent of bone destruction including cortical breakthrough and articular invasion. Intramedullary tumor growth and soft tissue extension was best detected with MRI. Apart from heterogeneity on MR images, DF displayed nonspecific low signal intensity on unenhanced T1-weighted images and an intermediate to high signal intensity including areas of low intensity on T2-weighted images. Desmoplastic fibroma showed a distinct, inhomogeneous gadolinium enhancement. Although cross-sectional imaging features of DF are nonspecific, some MR characteristics, such as inhomogeneous contrast enhancement and the presence of low-intensity regions on T2-weighted images, are helpful in determining the differential diagnosis. Cross-sectional imaging of DF is useful for local staging of the tumor because it provides valuable information about the extent of bone destruction as well as medullary and extraosseous spread.     

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.