MR Imaging Findings of a Primary Cardiac Osteosarcoma and Its Bone Metastasis with Histopathologic Correlation

An osteosarcoma of cardiac origin is extremely rare, and a comprehensive description of MR imaging (MRI) findings of cardiac osteosarcoma and its metastasis in the femur have not been reported in the literature. We present a case of cardiac osteosarcoma in a 47-year-old woman and its metastasis to the femur, focusing on the description of MRI findings of the cardiac and metastatic bony osteosarcoma with a histopathologic correlation.

MR Findings of Ossifying Fibroma with Pathologic Correlation

PURPOSE: To compare the MR imaging findings of ossifying fibroma with the histopathologic findings. MATERIALS AND METHODS: In eight patients (M:F=1:7; age range, 1-25 years) with pathologically proven ossifying fibroma, plain film and MR images were retrospectively analyzed in terms of signal intensity, homogeneity and patterns of contrast enhancement. The MR imaging findings and histopathology were correlated. Using 1.0-T and 1.5-T MR machines, axial T1 and T2 images and gadolinium-enhanced axial and sagittal T1 images were obtained. RESULTS: In all cases, iso-signal intensity to muscle was observed on T1-weighted images, and high signal intensity on T2-weighted images. After intravenous injection of gadolinium-DTPA in seven cases, intense contrast enhancement was seen in all lesions, which were homogenous on T1, T2, and enhanced MR images. Moderate cellularity of fibrous tissue, with even distribution of osteoid and an absence of secondary changes such as hemorrhage or cystic change were revealed by pathologic examination. CONCLUSION: Ossifying fibroma shows strong enhancement and homogenous signal intensity on MR images.The homogeneity of the MR signal depends on the even distribution of osteoid and an absence of secondary changes such as hemorrhage or cystic change.

MR Findings of Calvarial Eosinophilic Granuloma

PURPOSE: The purpose of this study was to evaluate the MR findings of calvarial eosinophilic granuloma. MATERIALS AND METHODS: We reviewed the MR imaging studies of nine patients [M:F=3:6, aged 6 -35 (mean, 20.5) years] with pathologically proven eosinophilic granuloma in the calvaria. The findings were evaluated for involvement of the diploic space, changes in adjacent bone marrow, distinction of the transitional zone, pattern of bone destruction, signal intensity and contrast enhancement of the tumor, and contrast enhancement of the adjacent dura. RESULTS: All lesions involved the diploic space, showed no change in adjacent bone marrow, and had a distinct transitional zone. In most (8/9) cases there was asymmetric bony destruction. On T1-weighted images, signal intensities of the tumors varied, while on T2-weighted images, hyperintensity was observed in seven cases, isointensity in one, and hypointensity in one. After the administration of contrast material, enhancement was homogeneous in four cases and inhomogeneous in five. Enhancement of the adjacent dura was demonstrated in all nine cases. CONCLUSION: The characteristic MR findings of calvarial eosinophilic granuloma are variable signal intensity on T1WI, high signal intensity on T2WI, and marked contrast enhancement; in addition, there is a distinct transitional zone, asymmetrical bony destruction, and associated dural enhancement.

MR Imaging Findings of Intraosseous Lipoma

PURPOSE: To evaluate the MR imaging findings of intraosseous lipoma. MATERIALS AND METHODS: The MR imaging findings of 12 cases of intraosseous lipoma were retrospectively analyzed with regard to internal signal intensity, enhancement patterns, the presence of calcification and the status of the margin. The findings relating to these last two features were compared with those of plain films and CT. RESULTS: Six tumors were located in the calcaneus, three in the tibia, two in the ilium, and one in the carpal lunate. A fat component was clearly identified in all cases, but no lesion was purely fatty. Cyst formation was noted in four cases, and hyperintense portions different from the cystic area were seen on T2WI in ten. Contrast enhancement was observed in four patients, and although plain film and CT images revealed, in all cases, the presence of calcification, in two cases this was not demonstrated by MRI. In all cases, however, MRI showed well-defined tumoral margins. CONCLUSION: MRI clearly depicts fat and other components related to the involutional changes occurring in cases of intraosseous lipoma. The information these images provide is useful for the diagnosis and histologic classification of intraosseous lipoma.

A Chondromyxoid Fibroma of the Fibula: A Case Report

Chondromyxoid fibroma is the least common benign bone tumor, accounting for less than 1% of all bone tumors. Pathologically, it is composed of varying proportions of chondroid, myxoid and fibrous elements. The most common anatomical site is the metaphyseal region of the long bone, and the typical radiologic appear-ance is a cortical expansile osteolytic lesion with a lobulated sclerotic margin, and septa. We report the plain and MRI findings of a relatively typical chondromyxoid fibroma occuring in the proximal fibula.

MR Imaging Findings of Chondroblastic Osteosarcoma

PURPOSE: To evaluate the MR imaging findings of chondroblastic osteosarcoma. MATERIALS AND METHODS: Weincluded 11patients (8 men, 3 women, mean age of 19 years) with pathologically proven chondroblastic osteosarcomaand, as a control group, 20 patients with conventional osteosarcoma. We obtained pre- and post-enhanced MR imagesof all patients and retrospectively reviewed the signal intensity and enhancement pattern of tumors. MR imageswere correlated with histopathology. RESULT: In chondroblastic osteosarcomas, the major portion (< 75%) of thetumor showed low signal intensity on T1-weighted images and homogeneous high signal intensity on T2-weightedimages, but did not show enhancement. The margin of the area showed a lobular pattern. Enhanced nodules (n=11) andstrands (n=8) were seen in the nonenhanced portion. Histopathologically, the nonenhanced portion, nodules, andstrands revealed a chondroid matrix, hypercellular area, and fibrovascular septa, respectively. Conventionalosteosarcomas showed heterogeneous enhancement ; six showed a focal (<25%) nonenhanced area representing necrosis. CONCLUSION: Chondroblastic osteosarcoma showed characteristic MR imaging findings.

Benign and Malignant Musculoskeletal Tumors Evaluated with the Aid of Pa rametric Maximum Slope and Blood Volume Images

PURPOSE: To assess the values of parametric "maximum slope(MS) and blood volume(BV)" images as indicators of tissue vascularization and perfusion in distinguishing benign from malignant musculoskeletal tumors. MATERIAL AND METHODS: Dynamic inversion recovery spin-echo echo-planar imaging (TR/TE/TI/NEX: 1 5 0 0 / 2 4 / 5 00 ms/1; matrix 128 x 128; slice thickeness 5 mm, interleaved) at 1.5-second intervals(200 phases) was performed after intravenous bolus injection of Gd-DTPA. A total of 32 pathologically proven muscu-loskeletal masses(benign 9, malignant 23) were included in this study. MS was derived by fitting a time-intensity curve using a polynomial model. BV was determined by integration until maximum slope was reached. On a pixel-by-pixel basis, MS and BV images were generated and displayed by gray-scale. We selected a region of interest(ROI, more than 6 x 6 pixels) including the highest value of the tumors and calculated mean values of MS and BV. Wilcoxon's signed rank test was used to compare benign tumors with malignant pre- and postchemotherapy tumors. RESULT: The mean values of ROIs selected on MS images were significantly different (p=.008) between benign (mean 3.33, range 0.01 -16.47 ) and prechemotherapy malignant(mean 8.54, range 1.61 -16.90) tumors, as were the mean values of ROIs on BV images(p=.005; benign tumors: mean 162.17, range 91.17 -2 8 3 . 7 ; prechemotherapy malignant tumors: mean 330.18, range 117.5 -845.1). MS and BV values of benign and malignant tumors overlapped but tended to be separated. CONCLUSION: BV and MS images may help distinguish benign from malignant musculoskeletal tumors.

Benign and Malignant Musculoskeletal Tumors Evaluated with the Aid of Pa rametric Maximum Slope and Blood Volume Images

PURPOSE: To assess the values of parametric "maximum slope(MS) and blood volume(BV)" images as indicators of tissue vascularization and perfusion in distinguishing benign from malignant musculoskeletal tumors. MATERIAL AND METHODS: Dynamic inversion recovery spin-echo echo-planar imaging (TR/TE/TI/NEX: 1 5 0 0 / 2 4 / 5 00 ms/1; matrix 128 x 128; slice thickeness 5 mm, interleaved) at 1.5-second intervals(200 phases) was performed after intravenous bolus injection of Gd-DTPA. A total of 32 pathologically proven muscu-loskeletal masses(benign 9, malignant 23) were included in this study. MS was derived by fitting a time-intensity curve using a polynomial model. BV was determined by integration until maximum slope was reached. On a pixel-by-pixel basis, MS and BV images were generated and displayed by gray-scale. We selected a region of interest(ROI, more than 6 x 6 pixels) including the highest value of the tumors and calculated mean values of MS and BV. Wilcoxon's signed rank test was used to compare benign tumors with malignant pre- and postchemotherapy tumors. RESULT: The mean values of ROIs selected on MS images were significantly different (p=.008) between benign (mean 3.33, range 0.01 -16.47 ) and prechemotherapy malignant(mean 8.54, range 1.61 -16.90) tumors, as were the mean values of ROIs on BV images(p=.005; benign tumors: mean 162.17, range 91.17 -2 8 3 . 7 ; prechemotherapy malignant tumors: mean 330.18, range 117.5 -845.1). MS and BV values of benign and malignant tumors overlapped but tended to be separated. CONCLUSION: BV and MS images may help distinguish benign from malignant musculoskeletal tumors.

MR Findings of Eosinophilic Granuloma

PURPOSE: To describe the MR findings for the three phases of eosinophilic granuloma, as defined by Mirra 'sconventional radiographic criteria. MATERIALS AND METHODS: Eighteen lesions in 14 patients with proveneosinophilic granuloma were retrospectively analyzed. Among this total, three vertebral lesions were excluded,and the remaining is were classified as early, middle, or late phase on the basis of Mirra's radiographiccriteria. For each phase, we compared MR findings with regard to signal intensity, homogeneity, contrastenhancement, perilesional marrow edema, and soft tissue change. For the three vertebral lesions excluded becausethe application of radiographic criteria was difficult, MR findings for paravertebral soft tissue reaction anddegree of cord compression were compared. RESULTS: Of the fifteen cases classified, eight were early phase, fivewere mid phase, and two were late phase. During each phase, all lesions except one, as seen on T1-weightedimages(T1W1), showed iso-signal intensity. On T2WI, all lesions showed high signal intensity. Contrast studydemonstrated marked contrast enhancement. Thus, no remarkable differences were found in the signal intensitydegree of contrast enhancement of each phase. With regard to heterogeneity, this was demonstrated in most earlyphase lesions, reflecting necrosis and hemorrhage of those lesions. Soft tissue swelling was more severe duringthe early phase than the mid or late phase, but marrow edema was similar in each of the three phase. One of threepatients with vertebra plana showed para-vertebral soft tissue swelling and cord compression, but this was notseen in the two other cases. CONCLUSION: For evalvating the extent of eosinophilic granuloma and its relationshipwith surrounding structures, MRI was superior to conventional radiography. During the early phase of the disease,lesions showed greater inhomogeneity and more aggressive soft tissue reaction than during the mid and late phase.The use of MRI for the evalvation of eosinophilic granuloma can help decide a therapeutic plan of action andfollow up evaluation.

Osteosarcoma after Preoperative Chemotherapy: Tissue Characterization with Specimen MR and the Role of Enhanced MR Imaging

PURPOSE: To evaluate the role of enhanced MR imaging in monitoring tumor response to preoperativechemotherapy for osteosarcomas. MATERIALS AND METHODS: Fo r t y - s even patients (30 males and 17 females, witha mean age 17 years ; range 8 -44 years) with osteosarcomas were included in this study. We obtained spin echoT1-, T2-, and enhanced T1-weighted images before and after pre-operative chemotherapy and in all patientscorrelated changes in MR parameters with histopathologic response. We also obtained 19 specimen MR images,correlating these with histopathologic results in order to estimate tissue specific signals. Patients with morethan 10% viable tumor in the resected specimen were considered poor respon-ders(n=26), while those with 10% orless viable tumor were considered good respon-ders(n=21). RESULTS: Four distinct patterns of signal intensitycorresponded, respectively to dead bone and dense fibrosis (low on T1- and T2-weighted images), viable tumor cells(in-termediate on T1- and high on T2-weighted images), necrosis (low on T1- and high on T 2 - weighted images),and hemorrhage (high on T1- and T2-weighted images), but a wide range of overlap was noted. In all four groups,viable tumor cells remained. Increased tumor vo l u m e, stable or increased edema and enhancement were goodpre-dictors of poor response (predictive values of 83%, 77%, and 89%, respectively). Decreased enhancement was theonly reliable predictor of good response (predictive value, 73%). Changes in tumor margin, homogeneity, signalintensity, and joint effu-sion did not correlate with histopathologic response. CONCLUSION: Signal intensities donot reflect histologic nature. Enhanced MR imaging is a useful predictor of tumor response to preoperativechemotherapy.

Osteosarcoma: Correlation of T1 Map and Histology Map

PURPOSE: To determine whether T1 mapping shows regional differences between viable and necrotic regions of osteosarcomas after anticancer chemotherapy and to assess whether this mapping is able to express the characteristics of various intramural tissue components. MATERIALS AND METHODS: Eleven of 20 osteosarcomas were included in this study, while the remaining nine were excluded because the tumor site was inappropriate for comparison of T1 map and tumor macrosection. All patients underwent MR imaging for the purpose of T1 mapping, followed by pre-operative chemotherapy and subsequentl limb-salvage surgery. Spin echo pulse sequencing was used with varying TR (100, 200, 400, 800, 1600, and 2400 msec) and a constant TE of 20 msec. Using a C-language software program, T1 relaxation time was calculated on a pixel-by-pixel basis and then a T1 map was generated by using a post-processing program, NIH Image. We attempted correlation of the T1 map and histologic findings, particularly in regions of interest(ROI) if certain areas were different from other regions on either the T1 or histologic map. Value was expressed as an average of the ratio of T1 of ROI and T1 of fat tissue, and this was used as an internal reference for normalization of the measurement. RESULTS: Tumor necrosis was 100%(Grade IV) in six specimens, and over 90 % (Grade III) in five. Viable tumor cells were found mostly in regions with chondroid matrix and seldom in regions with osteoid matrix. Regardless of cell viability, values ranged from 0.9 to 9.87(mean, 4.02) in tumor necrotic area with osteoid matrices, and from 3.04 to 3.9(mean, 3.55) in areas with chondroid matrices. Other regions with fibrous tissue proliferation, hemorrhage, and fatty necrosis showed values of 2.92-9.83(mean, 7.20), 2.65 -5.96(mean, 3.59), and 1.43 -3.11(mean, 2.68) respectively. The values of various tissues overlapped. No statistically significant difference was found between regions in which tumors were viable and those with tumor necrosis. CONCLUSION: Although we hypothesized that areas of necrotic tumor would show an increased water component(proton number) and would have a longer T1 value than viable tumor tissues, our results were otherwise. Necrotic osteosarcoma tissves showed a wide range of T1 values according to the prevailing tissue components.

Fluid-fluid Level on MR Image: Significance in Musculoskeletal Diseases

PURPOSE: To evaluate the frequency, number and signal intensity of fluid-fluid levels of musculoskeletaldiseases on MR images, and to determine the usefulness of this information for the differentiation ofmusculoskeletal diseases. MATERIALS AND METHODS: We retrospectively reviewed 30 cases in which fluid-fluid levelwas seen on MR images; they were diagnosed histopathologically(24/30), clinically(5/30) orclinicopathologically(1/30). To differntiate these diseases, we determined their frequency, the number offluid-fluid levels and the signal intensity of fluid. RESULTS: MR images revealed fluid-fluid levels in thefollowing diseases : giant cell tumor(6), telangiectatic osteosarcoma(4), aneurysmal bone cyst(3), synovialsarcoma(3), chondroblastoma(2), soft tissue tuberculous abscess(2), hematoma(2), hemangioma(1), neurilemmoma(1),metastasis(1), malignant fibrous histiocytoma(1), bursitis(1), pyogenic abscess(1), and epidermoid inclusioncyst(1). Fourteen benign tumors and ten malignant, three abscesses, and two hematomas were included. Unlike truetumors, hematomas, tuberculous abscesses and the epidermoid inclusion cyst showed only one fluid-fluid level in aunilocular cyst. On T1-weighted images, the signal intensities of fluid varied, but on T2-weighted images,superior layers were in most cases more hyperintense than inferior layers. CONCLUSION: Because fluid-fluid layersare a nonspecific finding, it is difficult to specifically diagnose each disease according to the number offluid-fluid levels or signal intensity of fluid. In spite of the nonspecificity of fluid-fluid levels, they werefrequently seen in cases of giant cell tumor, telangiectatic osteosarcoma, aneurysmal bone cyst, and synovialsarcoma. Nontumorous diseases such as abscesses and hematomas also demonstrated this finding.

Peritumoral Bone Marrow Edema in Benign Giant Cell Tumor

PURPOSE: To evaluate the frequency of peritumoral bone marrow(BM) edema accompanying benign giant celltumor(GCT) of the appendicular bone by magnetic resonance(MR) imaging and to correlate MRI findings with those ofplain radiography and bone scintigraphy. MATERIALS AND METHODS: Eighteen cases of pathologically proven benignGCT of the appendicular bone were retrospectively analyzed using MR images, plain radiographs and bonescintigrams. A plain radiograph was available in 15 cases, and a scintigram in six. Marrow edema was defined asperitumoral signal changes which were of homogeneous intermediate or low signal intensity(SI) on T1WI and high SIon T2WI, relative to the SI of normal BM, and homogeneous enhancement on Gd-DTPA-enhanced T1WI. The transitionzone, sclerotic margin and aggressiveness of the lesion were assessed on the basis of plain radiographs. BM edemaseen on MR images was correlated with plain radiographic and scintigraphic findings. RESULTS: 1. Peritumoral BMedema was seen on MR images in 10 of 18 cases (55.5%). 2. In 8 of 15 cases for which plain radiographs wereavailable, MR imaging revealed BM edema. In six of these eight, transition zone was wide, while in two it wasnarrow. Six of seven patients without marrow edema showed a wide transition zone, and in one this was narrow.There was significant correlation between BM edema shown by MR imaging and the transition zone seen on plainradiographs (x2, p<0.05). But The aggressiveness shown by plain radiographs correlated only marginally, while thepresence of sclerotic rim did not correlate. 3. All six cases for which a bone scintigram was available showed anextended uptake pattern. In five of the six, MR imaging revealed edema. CONCLUSION: Peritumoral BM edema wasfrequently seen (55.5%) in the GCTs of appendicular bone ; it was more often shown in association with a widetransition zone by plain radiographs.

MR Imaging in Symptomatic Osteochondromas

PURPOSE: To assess the MR findings of symptomatic osteochondromas. MATERIALS AND METHODS: We evaluated 31patients who between July, 1994 and May, 1997 underwent MR imaging for symptomatic osteochondroma. Fourteen were males and 17 were females, and their ages ranged from 8 to 49(mean, 23) years. Using T1WI, T2WI andgadolinium-DTPA-enhanced T1WI, images were analysed according to signal intensity in the osseous component of theosteochondroma, thickness of the cartilage cap, and associated change in surrounding soft tissue. RESULTS:Clinical manifestations included a palpable mass or tendency to grow(n=22) and pain on movement(n=9).Complications were of three types : that which followed change in the osseous component of the tumor, associatedchange in surrounding soft tissue, and malignant transformation. In the osseous component, bone marrow edema orcontussion was seen in 21 cases(67.7%), and in two(65%), fracture was observed. In surrounding soft tissue, muscleimpingement was seen in 21 cases(67.7%), bursitis was in 7 cases(22.6%), tenosynovitis in seven(22.6%), andvascular compression in five(16.1%). In three cases(9.7%), thansformation to chondrosarcoma had occurred ; two ofthese were derived from osteochondromatosis and one from a single osteochondroma. The thickness of the cartilagecap was as follows : 10mm(n=3). CONCLUSION: In patients with symptometicosteochondroma, MR imaging is useful for detecting both complications and malignant transformation.

Chondrosarcoma: MR Imaging Findings Correlated with Pathologic Classification and Grade

PURPOSE: To evaluate the MR imaging findings of chondrosarcomas by correlation with pathologic classificationand grade. MATERIALS AND METHODS: We performed MR imaging-pathologic correlation of nineteen chondrosarcomas. Conventional chondrosarcomas accounted for 15 cases (grade I : 6, II : 6, III : 3) and the mesenchymal and dedifferentiated types each accounted for two. MR signal intensity (SI) of the tumor on T1- and T2-weighted images(T1WI and T2WI, respectively), was classified as homogeneous or heterogeneous low-, iso- or high SI, and enhancing pattern as marginal, marginal and septal, marginal and nodular, or diffuse enhancement. RESULTS: Eighteen cases of chondrosarcomas (95%) showed homogeneous or heterogeneous low- or iso SI on T1WI and high SI on T2WI. Low gradeconventional chondrosarcomas showed marginal and septal (n=8/10) or marginal (n=2/10) enhancement on Gd-enhanced MR images. Grade III conventional chondrosarcomas showed marginal or marginal and nodular enhancement. Dedifferentiated and mesenchymal chondrosarcomas showed marginal and nodular or diffuse enhancement. CONCLUSION: Chondrosarcomas showed iso- or low SI on T1WI and high SI on T2WI. Marginal and septal enhancement was demonstrated on Gd-enhanced MR images of grade I and II conventional chondrosarcomas. If a tumor showed amarginal and nodular or diffuse enhancing pattern, this suggested it was a of high grade chondrosarcoma.

MR Imaging Findings of Malignant Fibrous Histiocytoma of Bone

PURPOSE: The purpose of this study is to assess magnetic resonance (MR) imaging findings of malignant fibrous histiocytoma (MFH) of bone and to evaluate the role of contrast-enhanced MR imaging in the diagnosis of bone MFH. MATERIALS AND METHODS: MR imagings of pathologically proven bone MFH in ten patients were reviewed. Enhanced study was also performed with Gd-DTPA. The MR images were evaluated for signal intensity, homogeneity, marginal definition, presence of internal septation, cortical destruction, soft tissue extension, joint involvement and contrast enhancement. RESULTS: Tumors showed iso- or slightly high signal intensity to muscle on T1-weighted images and heterogeneously high signal intensity on T2-weighted images. Four cases showed poor-marginated borderon T2-weighted images and four cases had internal septa. Eight of nine patients with intravenous administration of Gd-DTPA showed contrast enhancement, five were heterogeneous and three were homogeneous. All cases showed cortical destruction and soft tissue extension. Five cases showed joint involvement. CONCLUSION: Bone MFH showed similar MR imaging findings of soft tissue MFH or other malignant bone tumors, but joint involvement was suggestive finding of bone MFH.

MR Image Findings of Giant Cell Tumor of the Tendon Sheath Involving the Foot: A Case Report

Giant cell tumor of the tendon sheath(GCTTS) is a benign condition which involves the synovium of the tendonsheaths, and usually occurs around the small joints, e. g. the ankle, knee, and wrist. Histologically, GCTTS is similar to pigmented villonodular synovitis(PVNS). The authors report MRI findings of a GCTTS. This showed lower signal-intensity lesions than adjacent muscles on T1-weighted, proton density weighted, and T2-weighted images.