Magnetic resonance imaging of soft tissue tumors

This article outlines the ability of MR imaging in staging, grading, tissue characterization, and posttherapeutic surveillance of soft tissue tumors. Well-known staging parameters, such as extent, relationship with adjacent structures, and detection of intralesional necrosis, are used in the MR protocol for locoregional staging. Bone scintigraphy and high-resolution CT scan of the lungs are best methods for ruling out metastatic spread. A variety of (solitary or combinations of) grading parameters are described in the radiological literature. The role of MR imaging is to afford recognition of these lesions that need further aggressive work-up, excluding all others. Despite controversial reports, the definite role of MR imaging in grading of soft tissue tumors seems to become established. As for grading, a lot of individual imaging characteristics used for tissue characterization have low sensitivity, but combinations of parameters (age, site, signal intensities) are more useful and often allow to predict a specific diagnosis or to narrow down the list of differential diagnoses. Local recurrences of soft tissue tumors are frequent and can be detected accurately by an easy-to-use MR algorithm.     

Magnetic resonance imaging of soft tissue tumors of the hand and wrist

We will discuss the imaging characteristics of soft tissue tumors of the hand and wrist, especially the magnetic resonance imaging findings, since MRI has proven to be the gold standard for characterization of soft tissue tumors. Our series consists of 71 tumors of the hand and wrist, that were examined by magnetic resonance imaging. Fourty-four lesions were benign, 7 malignant, and 20 lesions were pseudotumoral masses. The signal characteristics often allow to make a correct diagnosis or to narrow down the list of differential diagnoses. It also allows to determine the extent of the lesion more accurately.     

Magnetic resonance imaging of musculoskeletal tumors: skeletal and soft tissue masses

The purpose of this article is to review the MRI characteristics of musculoskeletal tumors, including skeletal and soft tissue masses. MRI has become the premier imaging modality for the evaluation of musculoskeletal tumors because of its excellent soft tissue contrast, its sensitivity to bone marrow and soft tissue edema, and its multiple imaging planes. In a substantial subset of cases, MRI can provide a diagnosis or a short differential diagnosis, while certain tumors have no distinguishing signal characteristics. MRI of musculoskeletal tumors can also be challenging, because the MRI appearance of certain lesions can be misleading, and a knowledge of the instances in which MRI over- and underestimates the malignancy of lesions is invaluable. The importance of correct protocols for tumor evaluation, both in diagnosis and in pre-operative evaluation, are discussed. Common pitfalls that may over- or underestimate the aggresivity of lesions will be highlighted, as will the role of gadolinium enhancement in the evaluation of lesions. The MRI appearance of common benign and malignant muculoskeletal lesions will be illustrated.     

Magnetic resonance tomography of soft tissue tumors]

Soft tissue tumors are relatively often seen on MR tomography, although they make up a fairly small proportion of malignant lesions. To date, most soft tissue tumors have been investigated by MRI because of its unique soft tissue contrasts and its flexibility in slice orientation. But is MRI really adequate for staging and defining soft tissue tumors, or what role does it have pre-therapeutic work-up? Most malignant soft tissue tumors give rise to somewhat similar MRI findings and may not be sufficiently well characterized. On the other hand, some benign lesions can be clearly identified and staged. The goal of this paper is a critical discussion of the ability of MRI to define a lesion's degree of malignancy, to evaluate diagnostic criteria, and to describe requirements in the set-up of the investigation.     

Magnetic resonance imaging of peripheral soft tissue hemangiomas

Ten patients with soft tissue hemangiomas outside the central nervous system were studied with MR imaging. Eight patients were studied at 1.5 Tesla (T) with T₁-weighted and triple echo T₂-weighted sequences. Two additional patients were imaged on a 0.5-T system. The MR images were correlated with images from other modalities. Histologie diagnosis was obtained in all cases. It was found that prolonged T₂-weighted imaging together with standard spin echo T₁ and T₂ pulse sequences is a good substitute for contrast-enhanced CT and arteriographic evaluation of soft tissue hemangiomas.     

Magnetic resonance imaging of posttraumatic soft tissue disorders

The applications of magnetic resonance imaging with regard to musculoskeletal disorders have continued to expand over the past decade. It is considered to be the preferred imaging method for evaluation of soft tissue processes owing to its marked sensitivity to signal alterations in abnormal tissue, and it is capable of performing this function equally well in processes that affect the muscle, connective tissue, or subcutaneous tissue. In this pictorial essay, a review of many common posttraumatic soft tissue disorders and their characteristic magnetic resonance features, as well as some of the advantages of this imaging method, will be discussed.     

Magnetic resonance imaging of musculoskeletal soft tissue masses

The role of MR imaging in the evaluation of children with large, deep, or infiltrative soft tissue masses is to characterize and determine the extent of the lesion for treatment planning. There are a small number of soft tissue tumors with MR imaging appearances characteristic enough to allow a specific diagnosis, obviating biopsy. In the remaining cases with nonspecific imaging appearances, MR imaging is used for anatomic staging, but tissue sampling is still required for determining histology and grading.     

Magnetic resonance imaging of local soft tissue inflammation using gadolinium-DTPA

Chemical inflammation was induced subcutaneously in 10 rats using carrageenan mucopolysaccharide. Dual spin echo (SE) imaging of inflammatory loci was performed employing a 0.35 tesla resistive magnet. In addition, gadolinium-DTPA was administrated intravenously into 5 rats to evaluate the potential benefits of paramagnetic contrast medium for the detection and characterization of inflammatory loci. T2 weighted SE images demonstrated the edematous lesions as zones of high intensity. This was attributed to the increased relaxation times of lesions when compared to the adjacent soft tissue. The inflammation was also delineated on T1 weighted SE images, but only after injection of paramagnetic Gd-DTPA. Carrageenan mucopolysaccharide-induced lesions provide a useful experimental model for in vivo evaluation of soft tissue inflammation using magnetic resonance imaging. No special benefit of paramagnetic contrast enhancement was demonstrated in this model of local edema.     

Magnetic resonance imaging of benign soft tissue neoplasms in adults

This article reviews a spectrum of benign soft tissue tumors found in adults. Rather than presenting a complete review, the focus of this article is on benign tumors for which the diagnosis may be confidently made or strongly suggested on the basis of imaging. Diagnoses presented include nodular fasciitis, superficial and deep fibromatosis, elastofibroma, lipomatous lesions, giant cell tumor of the tendon sheath, pigmented villonodular synovitis, peripheral nerve sheath tumors, Morton neuroma, hemangioma, and myxoma.     

Gadolinium-DTPA enhancement of soft tissue tumors in magnetic resonance imaging

In a clinical study of 13 patients, gadolinium-DTPA (Gd-DTPA) was used for enhancement of soft tissue tumors at magnetic resonance imaging. Gd-enhanced T1 sequences were found to give additional information concerning tumor vascularity in 11 cases, tumor necrosis in 2 cases and tumor delineation in one case, compared with conventional T1 and T2 weighted spin echo sequences. If Gd-enhanced sequences were to be used as the only source of information, accurate assessment of tissue composition of the tumor would not have been possible. Furthermore, valuable information regarding tumor delineation towards surrounding fat may be lost.     

Magnetic resonance imaging of malignant soft tissue neoplasms in the adult

This review addresses the spectrum of malignant soft tissue tumors frequently found in adults. Rather than presenting a complete review, the focus of this discussion is on common lesions or lesions in which the diagnosis may be suggested on the basis of imaging. Diagnoses covered include undifferentiated high-grade pleomorphic sarcoma, fibrosarcoma, dermatofibrosarcoma protuberans, liposarcoma, synovial sarcoma, malignant peripheral nerve sheath tumor, clear cell sarcoma, hemangioendothelioma, hemangiopericytoma, angiosarcoma, and leiomyosarcoma.     

Magnetic resonance imaging of extraabdominal desmoid tumors.

The authors describe the MR appearance of extra-abdominal desmoid in three patients, with longitudinal follow-up during a period of up to 29 months in two of them. For the MR examinations various pulse sequences, including spin-echo and gradient-echo sequences, were used. Both non-enhanced and Gd-DTPA contrast enhanced studies were made. We found gradient-echo T2*-weighted sequences best suited for the detection of extra-abdominal desmoids. Best correlation between MR features and histologic findings was obtained on spin-echo T2- and contrast enhanced T1-weighted studies. Although preliminary, our results suggest that MRI might predict evolution of extra-abdominal desmoids by providing data about cellularity and relative amount of mucoid matrix of the lesions.     

Magnetic resonance grid analysis of soft tissue lesions.

Soft tissue tumors of seven patients were imaged with magnetic resonance imaging (MRI) prior to operative resection. In four cases, gross surgical specimen biopsy sites were broadly selected from areas of diverse signal intensity. A subsequently developed "grid analysis" technique, used in three additional patients, better localized differing zonal intensities within individual gross specimens. Further investigation of this technique is warranted, since MR images, when analyzed by means of a detailed grid technique, appear to enhance histologic diagnostic accuracy. Examination of larger segments of inhomogeneous soft tissue tumors is facilitated, while pathologists' sampling time is diminished.     

Vascular soft tissue tumors: medical imaging.

Histologically, tumors of the vascular system are divided into three categories. Benign types can be localized (hemangioma) or involve large segments of the body (angiomatosis). Vascular tumors of intermediate malignancy are known as hemangioendotheliomas. Angiosarcoma is one of the rarest malignant soft tissue neoplasms. The authors present the morphological and SI features of 17 histologically proven vascular tumors (16 benign, 1 malignant) examined by MRI. The results are compared with the findings on other imaging techniques. On T1-WI, the tumors are slightly hyperintense to muscle with interspersed areas of low SI corresponding to fibrous septa, calcifications, or fastly flowing blood, and areas of SI equal to fat. On T2-WI, the lesions are more homogeneous and markedly hyperintense to fat. MRI is superior to all other imaging techniques for evaluation of extent and characterization of vascular soft tissue tumors. Angiography remains helpful in demonstrating feeding or draining vessels.     

Magnetic resonance imaging of soft tissue changes in rheumatoid arthritis wrist joints

An increasingly aggressive therapeutic strategy, improved treatment options, and encouraging preliminary results have attracted growing attention to the potential of magnetic resonance imaging (MRI) in the diagnosis, prognostication, and monitoring of rheumatoid arthritis (RA). MRI offers multiplanar imaging with unprecedented soft tissue contrast and high spatial resolution. Synovitis, the primary joint lesion in RA, can be detected and monitored. By contrast, conventional radiography shows only the late signs of preceding synovitis. Other soft tissue changes, such as tenosynovitis, tendonitis, enthesitis, joint effusions, and ligament and tendon tears, can be visualized. Unfortunately, the image resolution in most clinically available MR units is insufficient for evaluation of wrist joint cartilage. Preliminary data suggest that MRI is a valuable tool in the diagnosis and prognostication of RA. The superior sensitivity of MRI may be of major significance in both clinical trials and practice. In trials, MRI may allow reductions in the trial size and length because of its more sensitive separation of responders from nonresponders. Thus, although thorough validation is awaited, particularly concerning the reproducibility and prognostic value, MRI seems to be a very promising method for assessment of both established and early RA.     

Magnetic resonance imaging of sacrococcygeal tumors

Five sacral tumors, 2 chordomas, 2 chondro- and/or osteosarcomas and one metastasis were examined with magnetic resonance imaging (MRI). The tumor delineation was excellent in all cases, and in several respects superior to CT. The signal pattern from the chordoma differed considerably from the other tumors suggesting a potential for tumor differentiation with MRI.     

Magnetic resonance imaging of orbital tumors

This contribution provides an overview of diseases of eye and orbit and their appearance on magnetic resonance imaging. In recent years the diagnosis of eye and orbit pathology has profited significantly from increasingly sophisticated technical developments in the field of tomographic methods. Due to the small size of the examination area the improvement in spatial resolution and soft tissue contrast leads to an increase in image quality. In most clinical questions concerning eye and orbit pathologies magnetic resonance imaging is superior to computed tomography and should be early performed.     

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

In 31 patients with 21 soft tissue and 10 bone tumors, magnetic resonance imaging (MRI) and computed tomography (CT) were equally effective in delineating the margins of most soft tissue tumors, and the margins of bone tumors from fat and adjacent normal bone. However, MRI was superior to CT in delineating bone tumors from adjacent muscle, and in showing the relationships to bone of the deep margins of some soft tissue tumors. This was true because the quality of CT images around thick cortical bone often was severely degraded by streak artifact, which does not occur in MRI.Excellent anatomic detail was achieved on MRI by spin echo pulse sequences with short repetition times. Bone tumors were delineated best by spin echo 1000/30 images, and soft tissue tumors by spin echo 1000/30 or inversion recovery images.     

Magnetic resonance imaging of myxoid containing tumors

Myxoid tissue forms part of many benign and malignant soft-tissue tumors. The advent of percutaneous needle biopsy has made it important to be aware of the diagnostic implications of biopsy samples containing myxoid tissue. To determine whether the magnetic resonance imaging (MRI) characteristics could help establish the diagnosis, we compared the MR images of 11 tumors containing myxoid tissue with the resected tumor tissue. In our small series of these rare tumors, the MRI characteristics allowed differentiation of intramuscular myxomas from malignant neoplasms containing myxoid tissue. Intramuscular myxomas meet the following conditions: (a) they are well circumscribed; (b) they arise within muscle; (c) T₁-weighted images demonstrate uniform, decreased signal intensity; (d) T₂-weighted images demonstrate uniform increased signal intensity; (e) contrast-enhanced images exhibit an inhomogeneous increase in signal intensity. If any of these conditions is not met, then a malignancy containing myxoid tissue should be suspected.