Magnetic resonance imaging of bone and soft tissue tumors: early experience in 31 patients compared with computed tomography

Fusion of Magnetic Resonance Elastography Images With Computed Tomography and Magnetic Resonance Imaging Using the Human Visual System

Magnetic resonance elastography (MRE) is used to assess the stiffness of the liver to rule out cirrhosis or fibrosis. The image, nevertheless, is regarded as shear-wave imaging and does not depict any anatomical features. Multimodality medical image fusion (MMIF), such as the fusion of MRE with computed tomography (CT) scan or magnetic resonance imaging (MRI), can help doctors optimize the advantages of each imaging technique. As a result, perceptions serve as valid and valuable assessment criteria. The contrast sensitivity function (CSF), which describes the rates of visual contrast sensitivity through the changing of spatial frequencies, is used mathematically to characterize the human visual system (HVS). As a result, we suggest novel methods for fusing images that use discrete wavelets transform (DWT) based on HVS and CSF models. Images from MRI or CT scan were combined with MRE images, and the outcomes were assessed both subjectively and objectively. Visual inspection of merging images was done throughout the qualitative analysis. The CT-MRE fused images in all four datasets were shown to be superior at maintaining bones and spatial resolution, despite the MRI-MRE being better at exhibiting soft tissues and contrast resolution. It is clear from all four datasets that the liver soft tissue in MRI and CT images mixed successfully with the red-colored stiffness distribution seen in MRE images. The proposed approach outperformed DWT, which produced visual artifacts such as signal loss. Quantitative evaluation using mean, standard deviation, and entropy showed that the generated images from the proposed technique performed better than the source images and DWT. Additionally, peak signal-to-noise ratio, mean square error, correlation coefficient, and structural similarity index measure were employed to compare the two fusion approaches, namely, MRI-MRE and CT-MRE. The comparison did not show the superiority of one approach over the other. In conclusion, both subjective and objective evaluation approaches revealed that the combined images contained more information and characteristics. Hence, the proposed method might be a useful procedure to diagnose and localize the stiffness regions on the liver soft tissue by fusion of MRE with MRI or CT.

Effect of cold rolling on the magnetic susceptibility of Zr-14Nb alloy

The magnetic susceptibility of cold-rolled Zr-14Nb was evaluated to apply a new metallic medical device used for magnetic resonance imaging (MRI). The magnetic susceptibility of cold-rolled Zr-14Nb decreased up to the reduction ratio of 30%, then gradually decreased up to the ratio of 90%. Transmission electron microscopic observation revealed the strain-induced formation of ω phase after cold rolling at the reduction ratio of 5%, indicating that the initial decrease in magnetic susceptibility was caused by the formation of the ω phase. The ω phase was saturated at the reduction ratio of 30%. The formation of the ω phase could be explained on the basis of the increase in the Young's modulus and Vickers hardness of cold-rolled Zr-14Nb. The effect of texture formation on these properties was not obvious in the cold-rolled Zr-14Nb. Because of the strain-induced formation of the ω phase, the magnetic susceptibility of Zr-14Nb can be reduced by cold rolling to as low as that of as-cast Zr-9Nb, which is one-third that of Ti and Ti alloys. Therefore, cold-workable Zr-14Nb with low magnetic susceptibility could be a promising alloy for medical devices under MRI.

MRI surveillance after resection for primary musculoskeletal sarcoma

This study reports the experience of one treatment centre with routine surveillance MRI following excision of musculoskeletal sarcoma. The case notes, MRI and histology reports for 57 patients were reviewed. The primary outcome was local tumour recurrence detected on either surveillance MRI in asymptomatic patients, or interval MRI in patients with clinical concern. A total of 47 patients had a diagnosis of soft-tissue sarcoma and ten of a primary bone tumour. A total of 13 patients (22%) had local recurrence. Nine were identified on a surveillance scan, and four by interval scans. The cost of surveillance is estimated to be £4414 per recurrence detected if low-grade tumours with clear resection margins are excluded. Surveillance scanning has a role in the early detection of local recurrence of bone and soft-tissue sarcoma.

Lymphedema: a comprehensive review

BACKGROUND

Lymphedema is a chronic, debilitating condition that has traditionally been seen as refractory or incurable. Recent years have brought new advances in the study of lymphedema pathophysiology, as well as diagnostic and therapeutic tools that are changing this perspective.

OBJECTIVE

To provide a systematic approach to evaluating and managing patients with lymphedema.

METHODS

We performed MEDLINE searches of the English-language literature (1966 to March 2006) using the terms lymphedema, breast cancer-associated lymphedema, lymphatic complications, lymphatic imaging, decongestive therapy, and surgical treatment of lymphedema. Relevant bibliographies and International Society of Lymphology guidelines were also reviewed.

RESULTS

In the United States, the populations primarily affected by lymphedema are patients undergoing treatment of malignancy, particularly women treated for breast cancer. A thorough evaluation of patients presenting with extremity swelling should include identification of prior surgical or radiation therapy for malignancy, as well as documentation of other risk factors for lymphedema, such as prior trauma to or infection of the affected limb. Physical examination should focus on differentiating signs of lymphedema from other causes of systemic or localized swelling. Lymphatic dysfunction can be visualized through lymphoscintigraphy; the diagnosis of lymphedema can also be confirmed through other imaging modalities, including CT or MRI. The mainstay of therapy in diagnosed cases of lymphedema involves compression garment use, as well as intensive bandaging and lymphatic massage. For patients who are unresponsive to conservative therapy, several surgical options with varied proven efficacies have been used in appropriate candidates, including excisional approaches, microsurgical lymphatic anastomoses, and circumferential suction-assisted lipectomy, an approach that has shown promise for long-term relief of symptoms.

CONCLUSIONS

The diagnosis of lymphedema requires careful attention to patient risk factors and specific findings on physical examination. Noninvasive diagnostic tools and lymphatic imaging can be helpful to confirm the diagnosis of lymphedema or to address a challenging clinical presentation. Initial treatment with decongestive lymphatic therapy can provide significant improvement in patient symptoms and volume reduction of edematous extremities. Selected patients who are unresponsive to conservative therapy can achieve similar outcomes with surgical intervention, most promisingly suction-assisted lipectomy.

Primary extraskeletal Ewing's sarcoma of the maxilla with intraorbital extension

Extraskeletal Ewing's sarcoma is often described as a tumour involving the soft tissues of the lower extremities and the paravertebral region. Primary Ewing's sarcoma of the cranium is extremely rare, with only 17 cases reported so far [24]. Involvement of the paranasal sinus is a very rare entity. Involvement of facial bones is characterized by clinical and radiological features distinct from those commonly observed in other sites. Because of the above peculiarities a delay in diagnosis and thus in starting treatment is very probable in such cases. Primary Ewings sarcoma rarely arises in the facial skeleton and only occasionally in the maxilla. To date, there have been 22 cases of maxillary Ewing's sarcoma reported in the English-language literature [25]. We report here a new case of Ewing's sarcoma localized to the maxillary sinus, nose and the orbit, successfully treated by surgery, local high dosage radiotherapy and systemic chemotherapy.

La tumeur d'Ewing

Ewing's tumor (ET) is a malignant bone tumor occurring in children and young adults. ET affects mainly bones of the central axis, and almost always involves soft tissue infiltration. The discovery of a unique genetic alteration, which is a reciprocal translocation most frequently resulting in the fusion of the EWS gene situated on chromosome 22 with the FLI-1 gene on chromosome 11, currently places ET among neuroectodermal tumors. Moreover, this translocation is a tumor-specific genetic marker at the basis of defining ET today and is used as a diagnostic and potentially prognostic tool complementary to imaging and histopathological work-up. Since the 1970 s, important progress has been made in the clinical management of ET patients. Multiagent chemotherapy in association with local treatment (surgery and/or radiation) has clearly improved outcome. The introduction of systemic treatment was justified by the frequent sub-clinical diffusion of apparently localized ET. Intensified therapeutic strategies have for the first time cured some metastatic ET patients, but at the cost of major side effects. Treatment is currently adapted as a result of a better definition of prognostic factors as well as a better assessment of its adverse effects. Improvement in global patient care and increased management of specific acute complications associated with ET (often interwoven with iatrogeneous effects) represent an important step towards improving the quality of life for ET patients as well as preventing long term complications. In the light of present studies, the majority of surviving adults today describe their health and quality of life as good. ET is a fascinating example of the progress made not only in the diagnostic and therapeutic approach to cancer but also in the comprehension of the mechanisms behind carcinogenesis, and consequently reflects the revolution of medicine over the last century.

Primary Ewing's sarcoma of the paranasal sinus with intracranial extension: imaging features

Extraskeletal Ewing's sarcoma is often described as a tumour involving the soft tissues of the lower extremities and the paravertebral region. Involvement of the paranasal sinus is a very rare entity. We present a case of primary Ewing's sarcoma of the paranasal sinus extending into the middle cranial fossa in a 40-year-old female. CT and MRI findings of this unusual case are discussed. To our knowledge, this case is the first to be reported with CT and MRI documentation.

Skip metastasis in osteosarcoma

Skip metastasis is rare in high-grade osteosarcoma and indicates a very poor prognosis. The authors describe two patients who had high-grade osteosarcoma and skip metastasis. MRI detected the skip lesion in both patients, and both lesions were confirmed by histology. The patients were treated with adjuvant chemotherapy and radical surgical resection. Both are alive and free of disease 3 and 6 years from diagnosis.

MR findings of primary Ewing's sarcoma of greater wing of sphenoid

Primary Ewing's sarcoma of the skull is a very rare entity. We report MRI findings in a case of Ewing's sarcoma of the greater wing of sphenoid in a 4-year-old patient. Magnetic resonance imaging showed markedly heterogenous signal intensity with areas of haemorrhage and necrosis. It also demonstrated the exact extent of tumour due to its multiplanar capabilities and was, therefore, helpful in planning surgery.

Primary bone tumors of the lower extremities

The key to adequate and accurate evaluation, diagnosis, and treatment of bone tumors is an organized and integrated approach involving the surgeon, radiologist, and pathologist. The radiologist plays not only a valuable role in the diagnosis and preoperative staging of bone tumors but may also play a role in biopsy and treatment. Despite the wide variety of imaging modalities available today, radiographs remain the mainstay in the evaluation of osseous neoplasms. Advanced imaging is. however. very useful for staging purposes and for characterization of the internal characteristics of tumors and may aid significantly in limiting the differential diagnosis. Although a detailed discussion of all ofthe various bone tumors of the lower extremities is beyond the scope of this article, an attempt is made to provide a framework for a rational and comprehensive approach to these complicated but relatively uncommon lesions. Certain lesions with unique characteristics are discussed to facilitate the diagnostic process.

Rib artifacts in electron beam tomography: incidence and severity without and with the cone beam reconstruction algorithm

Electron beam tomography (EBT) may be compromised by rib artifacts. Two hundred forty-seven abdominal studies were performed without (Group A, n = 222) or with (Group B, n = 25) the cone beam algorithm. One hundred eighty-six (83.8%) and nine (36%) studies of Groups A and B, respectively, displayed some level of artifact. In Groups A and B, major, minor, and no artifacts were found in 115 (51.5%) and 0 (0%), 71 (32.3%) and 9 (36%), and 36 (16.2%) and 16 (64%) patients, respectively (p < 0.01). The cone beam algorithm improves EBT studies of the abdomen.

Magnetic resonance imaging features of multilobular osteochondrosarcoma in 3 dogs

Three dogs with multilobular osteochondrosarcoma of the skull were evaluated using magnetic resonance (MR) imaging. Spin echo T1, T2, proton weighted and post contrast T1W images were obtained with a 1.5 Tesla magnet. The MR imaging findings were similar in all three dogs with mixed signal intensities in the T1W, T2W and proton weighted images and fairly large areas of contrast enhancement in the post contrast T1W images. The extent of brain and soft tissue involvement were well delineated and provided useful information concerning surgical planning. MR imaging provided a useful method of evaluating dogs with skull tumors.

The value of imaging in the diagnosis and treatment of bone tumors

The authors report their experience in the diagnosis of bone tumors at the Rizzoli Institute of Bologna. The main imaging techniques used to this purpose are conventional radiography, CT, MRI, and isotope bone scan. Angiography is rarely used. Conventional radiography is the examination of choice and is sufficient in several benign lesions not requiring treatment. Supplementary imaging studies are usually needed when radiographic findings are questionable and/or the lesion requires treatment. When a biopsy is required, it should be carried out after a complete imaging work-up, which sometimes allows a correct prebiopsy diagnosis, indicates the biopsy modality, approach and site, and is also mandatory to stage the tumor, plan the surgical approach and technique, and show in the finest details the occult tumor spread. CT best shows mineralized tissues and pulmonary metastases. It is also frequently used as a guide for needle biopsies. MRI beautifully shows the different tissues and compartments and it is particularly sensitive in depicting fat. Moreover, it can be repeated many times, even in pregnant women, because it needs no ionizing radiations and iodinated contrast; it is also free of artifacts in the patients with orthopedic devices which are usually nonferromagnetic. However, the execution of an adequate MRI requires experience and knowledge of bone pathologic conditions. Bone scan helps in detecting any 'active' area in the bone. It can be thus useful to depict lesion quiescence or activity and to stage any tumor which can metastasize to the skeleton. Bone scan is also helpful to show bone lesions when they are not visible on plain radiographs and indicates the tumor response to preoperative chemotherapy. Angiography is helpful when a preoperative selective embolization is needed, or when complex vertebral surgery or vascular surgery are planned. The bad outcome of bone tumors often depends on incomplete, inadequate or misinterpretated imaging findings.

The role of nuclear medicine in primary bone and soft tissue tumors

Although there is a limited role initially for staging the disease of primary bone and soft tissue tumors and for differentiation of benign from malignant lesions, nuclear medicine studies are recommended before starting treatment. A total body bone scan that includes a three phase study for the involved region helps to outline the vascularity of the lesion and both soft tissue and bony involvement, as well as involvement of other bones. A thallium 201 chloride or technitium 99m methoxy isobutyl isonitrile (SestaMIBI) tumor imaging study is recommended for baseline study and for future reference to evaluate the response to preoperative chemotherapy. This is of special importance to determine whether the patient needs an amputation or a limb-salvaging procedure. A follow-up thallium or 99mTc sesta MIBI study is not recommended early after surgery. A waiting period of at least 2 months is essential to avoid false-positive uptake caused by postoperative changes although this could be differentiated by comparing the ratios of lesion uptake in both early and delayed thallium imaging and with the ratios from the blood pool phase of the bone scan. Persistent thallium uptake in delayed images accompanied by ratios that are higher than the blood pool ratios is highly indicative of early recurrence. In the future, F-18 FDG tumor imaging acquired either on dedicated positron-emission tomography (PET) systems or by using a dual head gamma camera for coincidence detection will replace thallium and 99mTc sesta MIBI in those centers that have access to this technology. This is especially important at sites where thallium and MIBI have limitations because of normal uptake in adjacent organs.

The Ewing family of tumors. Ewing's sarcoma and primitive neuroectodermal tumors

There has been an explosion of new knowledge regarding the Ewing family of tumors over the past 5 to 10 years. Classical Ewing's sarcoma and PNET are now known to be the same tumor with variable differentiation, defined by a translocation between the EWS gene on chromosome 22 with one of three ETS-like genes, especially the FLI-1 gene on chromosome 11. Molecular techniques used to identify this translocation along with the knowledge that the protein product of the MIC2 gene is highly expressed on the cell surface have greatly improved our diagnostic abilities in this family of tumors. Controversy still exists as to whether surgery improves event-free survival when compared with radiotherapy in Ewing's sarcoma. The high second tumor rate, if nothing else, has started moving many physicians to preferentially use surgery when the functional results are predicted to be reasonable. The addition of ifosfamide and etoposide to standard therapy in Ewing's sarcoma has improved survival for patients without metastases at presentation. However, outcome for patients with metastases or who develop metastases while on therapy or shortly thereafter remains poor. Preliminary reports of better outcome with megatherapy are interesting but not yet definitive. The decades ahead will probably see marked changes in therapy for Ewing's sarcoma. The unique translocation seen in virtually all of these tumors is a potential target for a "magic bullet" therapy, because the protein product of this translocation is present only in the malignant cells. Hopefully either immune modulation against this unique protein or further knowledge of how to use antisense genes will move us toward exquisitely targeted therapy in the Ewing family of tumors.

Peripheral primitive neuroectodermal tumors. CT and MRI evaluation

The clinical, radiographic, and pathologic features of 17 patients with documented peripheral primitive neuroectodermal tumor (PNET) were evaluated in a retrospective study. The age at diagnosis ranged from 9 months to 46 years (median, 15.8 years). Primary sites of involvement were the abdomen (n = 8), extremities (n = 5), chest (n = 1), temporal bone (n = 1), maxilla (n = 1), and diploe (n = 1). At the time of diagnosis, six patients had distant metastases; all of these patients died, with an average survival of 8.8 months. Radiologic workup included standard radiographs, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), and bone scintigraphy. The radiographic appearance of these tumors was not specific for differentiation of PNETs from other types of bone and soft tissue tumors. The typical appearance resembled large non-calcified, soft tissue masses with cystic or necrotic areas. Heterogeneous enhancement with intravenous contrast agents was evident on CT, as was an intermediate signal intensity on Tl-weighted images and hyperintense signal on T2-weighted and STIR sequences. After gadolinium administration, variable enhancement was seen. MRI and CT were useful in predicting resectability, in detecting distant metastases, and in the evaluation of response to treatment. Surgery was performed in all cases, either for definitive diagnosis or for therapy. All patients received combined chemotherapy and radiotherapy and five patients received autologous bone marrow transplantation. Clinical follow-up was obtained over a mean period of 3 years (range 1 day to 6 years). Prognosis was poor with a median survival of 3.4 years. Our experience in 17 patients with peripheral neuroectodermal tumors indicates that although their radiologic features are non-specific, they should be included in differential diagnosis of soft tissue tumors of aggressive behavior, especially in a young age group. CT and MRI are useful in delineating the extent and resectability of tumor and in monotoring treatment.

Correlation of the findings of thallium-201 chloride scans with those of other imaging modalities and histology following therapy in patients with bone and soft tissue sarcomas

We performed a retrospective [corrected] study to evaluate the imaging potential of thallium-201 as compared with other imaging modalities in differentiating residual/recurrent tumors from post-therapy changes in patients with musculoskeletal sarcomas. 201Tl scans, magnetic resonance imaging (17), X-ray computed tomography (6) or contrast angiography (6) studies in 29 patients previously treated for musculoskeletal sarcomas were correlated with either histopathologic findings (26 patients) or 2-year clinical follow-up (three patients). All imaging studies were acquired within 2 weeks. Ratios of 201Tl tumor uptake to the contralateral (28 patients) or adjacent region of interest were calculated. When qualitative interpretation was in doubt, only those cases with a ratio of 1.5 or more were considered suggestive of recurrent of residual viable tumor tissue. Residual or recurrent tumor tissue was verified in 21 patients by biopsy. All had true-positive 201Tl scans while the other imaging modalities were true-positive in 20 and equivocal in one. In eight patients, there was no evidence of viable tumor tissue as proven by biopsy in five and long-term clinical follow-up in three. 201Tl scan was false-positive (ratio 1.5) in one patient and true-negative in seven while the other imaging modalities had four false-positives. The average 201Tl ratios were 2.8+/-1.1 in the true-positive cases and 1.3+/-0.3 in the true-negative cases. The percentage sensitivities, specificities, and accuracy for 201Tl were 100%, 87.5%, and 96.5% versus 95%, 50%, and 82.7% respectively for other imaging modalities. These results indicate that 201Tl scintigraphy is more accurate than other imaging modalities in differentiating residual/recurrent musculoskeletal sarcomas from post-therapy changes.

Magnetic resonance imaging of musculoskeletal tumors

In summary, MRI is the preferred modality for the evaluation of a soft-tissue mass following radiography. The radiologic appearance of certain soft-tissue tumors or tumor-like processes such as benign fatty tumors, intramuscular hemangiomas, pigmented villonodular synovitis, and certain hematomas may be sufficiently unique to allow a strong presumptive radiologic diagnosis. It must be emphasized that MRI cannot reliably distinguish between benign and malignant lesions and, when radiologic evaluation is nonspecific, one is ill advised to suggest a lesion is benign or malignant solely on its MR appearance. The role of MRI in the evaluation of bone tumors is predominantly one of staging. MRI is superb to evaluate the extent of intraosseous and soft-tissue involvement as well as the relationship of the lesion to the neurovascular bundle. Unfortunately, MRI remains nonspecific and is unable to predict lesion histology. Finally, the value of Gd-DTPA enhanced imaging is still to be determined.

Diagnostic procedures and pretreatment evaluation of soft tissue sarcomas

The diagnosis and preoperative evaluation of patients with a suspected soft tissue sarcoma involve several important considerations to ensure optimal treatment outcomes. Biopsy techniques must involve the retrieval of adequate tissue to establish the histologic diagnosis and grade of the tumor without compromising the subsequent definitive surgical resection. CT or MRI techniques represent the gold standard to evaluate the local extent of disease which is necessary to ascertain surgical resectability and/or the need for radiation therapy. CT scanning of the lungs is mandated for all patients with sarcomas to evaluate for metastatic disease and, for patients with abdominal or retroperitoneal tumors, scanning of the liver should also be included. Accurate staging of these patients will help define overall survival.

Magnetic resonance imaging of the spine: An initial experience

Retrospective analysis was carried out for 447 magnetic resonance imaging (MRI) studies of the spine. The overall mean age +/- SD of the entire series was 38.7 +/- 12.9 years. Degenerative spinal lesions and prolapsed intervertebral disks were detected in 62% and 73% of all the studies and of those which showed spinal abnormalities respectively. Postoperative granulation tissue was the third most common abnormality detected (12%). MRI was superior to computed tomography (CT) and CT myelograms in the diagnosis of disk prolapse (97% versus 66%), degenerative disease of the spine (94% versus 48%), and postsurgical granulation tissue (100% versus 6%). Comparing the numbers of CT and CT myelograms requested in the year prior to the installation of the MRI to the numbers requested during the year where the MRI was functioning did not show any change in the frequency of ordering CT studies. We conclude that our hospital-based series has shown an interesting pattern for spinal disorders. The first year experience of the utilization of MRI in various spinal diseases has been satisfactory with prevailing diagnostic superiority for that modality.

MRI of fibromatosis: with pathologic correlation

Fibromatosis refers to group of benign but sometimes locally aggressive proliferative lesions of myofibroblasts. These are characterized by infiltrative growth, and hence may mimic a malignant lesion. These lesions reveal a low signal intensity on T1-weighted pulse sequences, but may show low or high signal intensity on the T2-weighted sequences. Histologic correlation reveals that the lesion showing low signal intensity on T2-weighted sequences has a larger collagenous component, and reduced cellularity compared with the lesion showing high signal intensity on T2-weighted sequences.

Magnetic resonance imaging of the shoulder

The authors have reviewed the field of magnetic resonance imaging of the shoulder. This review includes abnormalities of the rotator cuff mechanism and glenoid labrum, and other disorders.

MRI of aggressive bone lesions of childhood

MRI can yield valuable information about involvement of bone and soft tissue by aggressive bone lesions of childhood. The 18 lesions evaluated with MRI included osteosarcoma, Ewing's sarcoma, histiocytosis, osteomyelitis, osteoblastoma, giant cell tumor, aneurysmal bone cyst, ossifying fibroma, and fibrous dysplasia. In 12 children, where CT correlation was available, MRI provided equal or more information than CT. Our study shows that MRI should be the modality of choice in the evaluation of aggressive bone lesions of childhood, after conventional radiography.

A review of imaging practice in bone and soft tissue lesions

Thirty six consecutive bone and soft tissue lesions which were referred to the Bone Transplantation Service between January 1987 and June 1989 were reviewed with respect to the information provided by pre-operative CT, MR and plain X-ray and the final histopathologic diagnosis. The ability of CT and MR to demonstrate cortical destruction, periosteal reaction, a soft tissue mass and soft tissue calcification was scored on a scale of one (low suspicion of abnormality) to four (definite abnormality) in each case. Of the thirty six cases reviewed there were twenty-two histologically confirmed tumours with all of the above three imaging modalities available for comparison. In each of these tumours MR was found to provide an equal or more accurate assessment of soft tissue extent. On a scale of 1 to 4 the average point scores were 3.6 and 2.6 for MR and CT respectively. Little difference was shown between CT and MR with respect to medullary involvement (4.0 points vs. 3.9) and cortical destruction (2.5 points vs. 2.7). CT (3.7 points) was more sensitive than MR (1.2 points) in detecting fine soft tissue calcification. In only five cases did the radiology report correctly nominate the histologic diagnosis and thus the role of imaging was more valuable in staging than diagnosis. For this reason a management oriented report should include comment regarding cortical destruction, the intramedullary extent of tumour and the extent of soft tissue involvement. MR is recommended in the investigation of all suspected malignant soft tissue or bone tumours.

Atypical appearance of lipomatous tumors on MR images: high signal intensity with fat-suppression STIR sequences

Lipomatous tumors generally have signal characteristics that allow them to be diagnosed with great accuracy by means of magnetic resonance imaging. These tumors usually have signal intensities similar to those of subcutaneous fat on both T1- and T2-weighted spin-echo images. Previous reports have not, to the authors' knowledge, described the appearance of lipomatous tumors on images obtained with a short-inversion-time inversion-recovery (STIR) sequence, which can be used to suppress signal from fat. Three lipomatous tumors (two liposarcomas and one lipoma) with signal characteristics unlike those of normal subcutaneous fat at all pulse sequences are presented.

Magnetic resonance appearance of fibromatosis. A report of 14 cases and review of the literature

We reviewed retrospectively the magnetic resonance (MR) images of 14 soft-tissue lesions of fibromatosis (desmoid tumors) encountered in 11 patients. The lesions were typically inhomogeneous in texture and round to oval in configuration. Margins were well-defined in 78% of the lesions at presentation and were infiltrating in all recurrences. On T1-weighted spin echo MR images, the predominant signal intensity was either isointense or minimally hyperintense when compared with skeletal muscle. On T2-weighted MR images the predominant signal intensity was typically intermediate between skeletal muscle and subcutaneous fat or isointense to fat. Linear and curvilinear areas of decreased signal intensity were distributed throughout the lesions on both pulse sequences in 86% of cases. This pattern strongly suggested fibromatosis. Speculation concerning possible etiologies of this appearance are discussed, and the relevant literature on previously reported cases is reviewed.

Negative scintigraphy with positive magnetic resonance imaging in bone metastases

We report three patients with known primary tumor in whom radionuclide skeletal imaging for metastatic disease was normal with or without clinical symptomatology referable to this area. Magnetic resonance imaging (MRI) of the spine demonstrated focal areas of abnormal signal intensity in the vertebral bodies of these patients. In all three patients, biopsy confirmed metastatic disease. All the patients received radiation or chemotherapy depending upon the etiology. These preliminary data suggest that MR imaging may be useful in evaluating patients with known primary tumor in whom clinical suspicion persists despite a negative radionuclide bone scan.

Magnetic resonance imaging: comparison of four pulse sequences in assessing primary bone tumours

A prospective magnetic resonance imaging (MRI) study was carried out in 13 patients (19 examinations) with primary bone tumours to assess the relative value of each of four pulse sequences in showing the extent and nature of the lesion. The four pulse sequences used were a T1-weighted spin-echo (SE544/44), a T2-weighted spin echo (SE1500/80), a short TI inversion recovery (STIR) (IR500/100/44), and a partial saturation (PS) (PS500/22) with field echo data collection. For soft tissue disease the combination of PS and STIR gave better definition of the boundary of the tumour than the more conventional T1 and T2-weighted spin echo sequences. For the demonstration of bone cortex, periosteal change and calcification, T1 and T2-weighted spin echo sequences were better. However, for calcified tissues, plain radiographs were better than either MRI combination. On the assumption that plain films will be available in all cases, PS and STIR sequences could therefore be substituted for T1 and T2-weighted spin echo sequences allowing an increase in soft tissue detectability for lesions in both red and yellow marrow.

Synovial sarcoma: MR imaging

Ten patients with biopsy-proved synovial sarcoma were evaluated by magnetic resonance (MR) imaging on a 1.5-T unit. The lesions showed intermediate signal intensity on T1-weighted images and heterogeneous high signal intensity on T2-weighted images. Tumors were well-demarcated from normal tissues. Additional information included adjacent bone involvement (one case), femoral vein invasion by tumor (one case), and hemorrhage within the tumors (one case). Four patients underwent a repeat MR examination following chemotherapy. This showed a decrease in size and increase in the signal intensity of three tumors on T2-weighted images, proven to be due to necrosis in one. These changes correlated with clinical regression of disease. While MR in synovial sarcoma does not have any specific signal intensity, it proved to be useful in defining the extent of disease and in determining the response to chemotherapy.

The role of magnetic resonance imaging in the evaluation of Ewing sarcoma. A report of 27 cases

The experience with magnetic resonance imaging (MRI) in 27 patients with Ewing sarcoma is reported and compared with computed tomography (CT) and plain films. Plain radiography proved to be the best imaging method to asses probable histological diagnosis in all cases (n = 6). For the evaluation of chemotherapeutic response (n = 4), CT and MRI gave the same information about the variation in size of the tumor. In this small series, the high signal in T2 weighted images was not altered significantly by therapy. In preoperative evaluation (n = 14), MRI gave better information than CT of soft tissue involvement and extension within the bone marrow in two cases each. The ability of MRI to accurately define extension through the epiphyseal plate in two cases permitted limb salvage which otherwise would not have been possible. In the long-term follow-up (n = 12), three patients without recurrence one year after therapy showed a low signal in the surgical area in T2 weighted images. Nine patients had a high signal in T2 weighted images: four were reactive lesions, two had obvious recurrence, and one was a hematoma. In the two remaining cases plain films and CT were normal, in the presence of both active tumor and reactive lesions. It was not possible with MRI to differentiate active tumor from reactive change, even after Gd-DTPA infusion.

Magnetic resonance imaging of soft tissue masses: an evaluation of fifty-three histologically proven tumors

Fifty-three histologically confirmed soft tissue masses in 48 patients were evaluated by magnetic resonance imaging (MR) and computerized tomography (CT). Twenty-three of these were malignant, twenty-three benign and seven of intermediate malignancy (all aggressive fibromatosis). The two procedures were compared for sensitivity and delineation of masses, their relationship to important neurovascular structures, their potential for histological diagnoses, their relative roles in influencing the surgical approach and the preferred modality in the follow-up for detection of tumor recurrence. Both modalities have their relative strengths and weaknesses. However, the superior contrast resolution of magnetic resonance imaging, its demonstration of lesions not clearly identified by CT, its pluridirectional capabilities and its ability to demonstrate large soft tissue tumors in a single coronal or sagittal plane makes it the preferred initial modality for evaluation of the soft tissue tumor of uncertain etiology and also in the follow-up of these patients. Despite MR's superiority in anatomically staging soft tissue tumors it, like CT, is of limited value in characterizing soft tissue sarcomas.

The role of magnetic resonance imaging in giant cell tumor of bone

In six cases of giant cell tumor the magnetic resonance (MR) images obtained with various pulse sequences and field strengths were compared to the corresponding computed tomography (CT) scans and plain roentgenograms. MRI was superior to CT and plain films in demonstrating areas of tissue inhomogeneity within the tumor as well as soft tissue extension. CT was superior in demonstrating cortical thinning. Multiplanar imaging capability and visualization of articular cartilage may demonstrate intra-articular tumor spread. The characteristic MRI findings with short TR/TE (T1-weighting) and long TR/TE (T2-weighting) are described. We also describe one case where serial MR scans were used to assess response to therapy.

Pre-operative assessment of soft tissue sarcomas by computed tomography

The current trend towards limb-sparing surgery in patients with soft tissue sarcomas has increased the need for accurate pre-operative assessment of the primary tumour. Tumour site, extent and relationship to bone and neurovascular structures determine whether adequate radical surgery is feasible or whether more limited excision as a part of multimodality treatment is appropriate. Pre-operative computed tomography (CT) was compared with operative findings in 38 patients with soft tissue sarcomas. CT prediction of muscle group involvement by tumour was correct in 95 per cent and prediction of major artery or vein invasion was correct in 92 per cent and 97 per cent respectively. Assessment of tumour relationship to major peripheral nerve was accurate for thigh sarcomas but was not possible in upper limb tumours. While CT confirmed frank bony involvement in two patients, it failed to distinguish between tumours closely adjacent to periosteum and those with periosteal invasion. Detection of residual or recurrent tumour nodules is less reliable; CT is most accurate before any surgical intervention.

Application of magnetic resonance imaging and computerized tomography as an adjunct to the surgical management of soft tissue sarcomas

Magnetic resonance imaging (MRI) and computed tomography (CT) scans of 53 evaluable patients with biopsy-proven soft tissue sarcomas were reviewed and compared with operative results to ascertain the accuracy for each imaging modality to predict resectability. Location of soft part sarcomas included: abdomino-pelvic (3), retroperitoneal (7), extremity (35), and other anatomic sites (8). MRI was observed to have greater accuracy than CT to preoperatively predict resectability (96.2% vs. 75.5%, respectively, p = 0.0034) following three-dimensional, multiplanar evaluation. Further, MRI was judged to have superior sensitivity to CT (95.6% vs. 73.3%, respectively, p = 0.006) and equivalent specificity (100% vs. 87.5%, respectively, p = 0.125). MRI represents a sophisticated diagnostic imaging technique to differentiate normal tissue from soft tissue sarcomas with superior contrast resolution in multiplanar imaging. MRI is considered to be the imaging modality of choice for these tumors with the advantage of not exposing the patient to ionizing irradiation or intravenous contrast agents to delineate contiguous structures.