MRI features of expansive processes of soft tissues. Contribution to etiologic diagnosis. Apropos of 32 cases

This study concerns the investigation of 32 soft-tissue tumors by MRI, subsequently verified by biopsies or surgery (n = 28) or other investigations (n = 4). MRI can suggest the diagnosis in some cases: lipomas cysts, hematomas, neuromas, desmoid tumors, hemangiomas, by contrast analysis and morphologic aspects; sometimes, malignant lesions are suspected on particular anatomic criteria. MRI is excellent in the evaluation of local extension. MRI can therefore be performed when the staging of soft tissue tumor is incompletely provided by other investigations (CT or US).     

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.     

Staging muskuloskeletaler Tumoren in der Bildgebung

The staging of primary malignant bone and soft tissue tumors requires adherence to a unified staging system. The staging system of the American Joint Commission for Cancer, the Enneking system, and the Hajdu system are described in respect of the radiologic staging criteria. Plain film radiography can estimate the biological aggressiveness of a bone tumor and in many cases narrow the differential diagnosis. Computed tomography is most sensitive in depicting cortical erosions and calcified periosteal reactions as well as in screening for distant metastasis. Angiography is mainly employed for vascular tumors and for the monitoring of interventional procedures such as tumor embolization. For both bone and soft tissue tumors, magnetic resonance tomography is the method of choice for the staging of intra- and extramedullary tumor extension, for the differentiation of neighboring compartments, and in the detection of invasion of the regional neurovascular bundle. After administration of contrast agents, the mode of enhancement gives further information on the nature of the tumor. With consistent application of the staging criteria in preoperative imaging, limb-saving therapy can be employed more often and the prognosis of the disease can be improved.     

Ganzkörper-MRT und FDG-PET/CT in der bildgebenden onkologischen Diagnostik

The advent of whole-body MRI (WB-MRI) has introduced a systemic approach to oncologic imaging compared to established sequential, multi-modal diagnostic algorithms. Hardware innovations, such as whole-body scanners at 1.5 Tesla and also recently 3 Tesla, combined with acquisition acceleration techniques, have made WB-MRI clinically feasible. With this method dedicated assessment of individual organs with various soft tissue contrast, high spatial resolution and contrast media dynamics can be combined with whole-body anatomic coverage. PET/CT has established itself as a powerful modality in the staging of patients suffering from malignant tumors. In addition to the morphologic information provided by the CT component of this hybrid modality, the PET component contributes invaluable metabolic information, which greatly enhances accuracy in the assessment of lymphatic spread and viability of tumor tissue. Whole-body MR diffusion imaging is a novel and promising technique which may contribute to superior sensitivity in the detection of tumor manifestations. In the assessment of distant metastatic spread WB-MRI is highly sensitive and has advantages over PET/CT, especially in those tumors frequently spreading to the liver, bone or brain. WB-MRI is also very attractive as a radiation-free alternative for imaging of pediatric tumor patients in whom multiple follow-up examinations may be required. WB-MRI allows for precise assessment of the bone marrow and has been proven to be highly accurate for the staging of hematologic diseases, such as multiple myeloma. In this article recent developments and applications of WB-MRI in oncologic imaging are addressed and compared to the results of PET/CT.     

MRI of soft tissue tumors

Magnetic resonance imaging (MRI) is the only noninvasive method of defining a soft tissue tumor. The extent of the tumor and the question of involvement or noninvolvement of various adjacent tissues and structures can be determined. This information, determination of lymphatic and distant metastatic spread, is invaluable for staging and management of the disease. Whether or not the tumor type can be reliably determined, or even whether the malignant or benign nature of the tumor can be ascertained on MRI examination, is open to question. Review of the literature indicates proponents on both sides of the issue. This review illustrates the imaging features that are relevant to suggesting a histologic diagnosis, and the pitfalls that are encountered in trying to determine the malignancy or benignity of a lesion. The clinical significance of these determinations is also discussed.     

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.     

兔VX2软组织肿瘤模型的建立及扩散张量成像研究初探

目的:建立恶性软组织肿瘤动物模型并初步探讨扩散张量成像(DTI)诊断软组织肿瘤的可行性及价值。方法:20只新西兰大白兔,右侧大腿近段注射VX2肿瘤组织悬液0．2 ml,于肿瘤组织接种后第40天行MRI常规扫描和 DTI成像,扫描图像经AW 4．0工作站处理,计算并分析肿瘤实质区、坏死区、肿瘤周边区、肿瘤邻近正常肌肉及对侧正常肌肉的平均ADC值、部分各向异性值(FA)、各向同性值(Iso)和体积与各向异性比值(VrA)。结果:所有兔大腿肌肉VX2 肿瘤模型均成功建立。肿瘤实质区与肿瘤坏死区、肿瘤周边区、邻近及对侧正常肌肉的FA值相比,差异均有极显著性意义(P<0．01)。肿瘤实质区与肿瘤坏死区、邻近及对侧正常肌肉的平均ADC值和VrA值差异有极显著性意义(P<0．01), 与瘤周区差异无显著性意义(P>0．05)。肿瘤邻近正常肌肉与对侧正常肌肉各参数值差异无显著性意义(P>0．05)。Iso 值在正常肌肉与不同区域肿瘤组织间差异有显著性意义(P<0．05)。结论:兔VX2软组织肿瘤模型可作为软组织肿瘤 MRI研究的动物模型,扩散张量成像能用于评价软组织肿瘤的内部结构特征及与周围组织的关系,其对良、恶性软组织肿瘤鉴别诊断的价值有待选一步研究。     

Imaging techniques in the preoperative diagnosis of soft tissue tumors. A comparison of MRT, CT, sonography, angiography and conventional x-rays]

In a study on 51 patients with histologically confirmed soft tissue tumors (STT), we retrospectively evaluated the preoperative use of imaging procedures (MRI, CT, ultrasound, angiography, plain film) for identification of tumor size, delineation, and determination of malignancy and tissue type. The findings were correlated with intraoperative findings and histological diagnosis. The overall diagnostic method of choice for preoperative imaging of STT is MRI, followed by CT. Ultrasound, although sensitive, lacks the required specificity. Angiography and plain film can only be used for specific indications, as they generally do not make it possible to stage the tumor. Combining our results with those from the more recent literature, we propose a diagnostic algorithm according to which MRI would generally be performed for preoperative staging of STT. CT and plain film should only be used if bony infiltration is suspected; angiography is indicated for planning intraarterial chemotherapy or embolization or if vascular infiltration is probable.     

MRT-Morphologie von Knochentumoren und tumorähnlichen Läsionen

Spin-echo sequences are mandatory at MRI for staging and characterization of bone tumors and tumor-like lesions. MRI is of minor value in the estimation of the malignant potential of an osseous lesion. Although many bone tumors and tumor-like lesions present similar morphology at MRI, some entities can be diagnosed with good reliability. These include chondrogenic tumors, solitary and aneurysmal bone cysts, giant cell tumors, lesions containing fatty tissue and, to a certain extent, osteoid-osteomas and osteoblastomas. Practical advice is given regarding when to perform a MRI study in cases of tumor suspicion. Further advices are given for cases a tumor is found incidentally at a MRI study, how to modify the study and which kind of tumor may be present.     

MR imaging of primary bone and soft tissue tumors

MR imaging of 131 cases with pathologically confirmed primary bone and soft tissue tumors were studied. They included 44 bone tumors (25 benign tumors, 19 malignant tumors) and 87 soft tissue tumors (55 benign tumors, 32 malignant tumors). MR imaging was performed on 0.5T, superconductive magnet system. All tumors were evaluated with T1-weighted, T2-weighted and STIR images. In some cases, contrast enhanced MR imaging with Gd-DTPA was applied. MR imaging was proving to be a valuable technique in the evaluation of patients with primary bone and soft tissue tumors. MR imaging was superior to the other modalities in delineating the extent of the tumor and their relation to surrounding structures in all cases. However, plain radiography and CT were more useful for evaluation of calcification, ossification, cortical destruction and endosteal/periosteal reaction than MR imaging. Direct sagittal and coronal images from MR imaging added accurate assessment for the relation between the tumor and their adjacent structures. MR imaging was of limited value in distinguishing benign from malignant tumors with the demonstration of tumor structures only, especially soft tissue tumors. But in bone and soft tissue tumors which have specific morphologic features and intensity patterns, MR imaging was very useful for diagnosis.     

Malignant granular cell tumor of the multifidus muscle: Case report and review of the literature

Granular cell tumors (GCTs) are uncommon soft tissue tumors characterized by cytoplasmic granular appearance of the neoplastic cells. Malignant GCTs comprise less than 2% of GCTs and are mostly found in the subcutaneous soft tissues of the lower extremities, especially the thighs. This report presents a case of malignant granular cell tumor in the right multifidus muscle. A 69-year-old woman presented to the surgeon with a 3 month history of light pain in the lumbar area and hip joint, with no particular history. CT and MRI revealed a soft tissue tumor with a maximum diameter of 7.5 cm. There is patchy unenhanced hypointense shadow in the mass. Widely excision was performed for the primary tumor, which was interpreted as an malignant GCTs. GCTs should be considered in the differential diagnosis in a rapidly growing intramuscular tumors. We investigated the CT and MRI findings of malignant granular cell tumor.     

Imaging of benign and malignant soft tissue masses of the foot

The foot is a relatively uncommon site of neoplastic and non-neoplastic soft tissue tumors. Although it contains a relatively small amount of somatic soft tissue elements, the foot is considerably rich in tendons, fasciae, retinaculae, and synovium. Corresponding to this distribution of soft tissue elements, some soft tissue lesions, such as giant cell tumor of tendon sheath, fibromatosis, and synovial sarcoma, are commonly seen in this location. Vascular tumors represent common soft tissue masses of the foot as well. Magnetic resonance imaging is the modality of choice in the assessment of soft tissue tumors. The presence of a suspected lesion can be confirmed and tumor margins can be defined accurately. In general, MRI does not provide histologic specificity, but considering some MR features may often help in correctly distinguishing benign from malignant lesions. In addition, characteristic features of the most common benign tumors (i.e., fibromatosis, cavernous hemangioma) and reactive processes of the foot (ganglion cyst, Morton's neuroma) often suggest a specific diagnosis. Electronic Publication     

Role of magnetic resonance imaging in the detection and characterization of solid pancreatic nodules: An update

Pancreatic ductal adenocarcinoma is the most common malignant tumor of the pancreas. The remaining pancreatic tumors are a diverse group of pancreatic neoplasms that comprises cystic pancreatic neoplasms, endocrine tumors and other uncommon pancreatic tumors. Due to the excellent soft tissue contrast resolution, magnetic resonance imaging (MRI) is frequently able to readily separate cystic from noncystic tumors. Cystic tumors are often easy to diagnose with MRI; however, noncystic non-adenocarcinoma tumors may show a wide spectrum of imaging features, which can potentially mimic ductal adenocarcinoma. MRI is a reliable technique for the characterization of pancreatic lesions. The implementation of novel motion-resistant pulse sequences and respiratory gating techniques, as well as the recognized benefits of MR cholangiopancreatography, make MRI a very accurate examination for the evaluation of pancreatic masses. MRI has the distinctive ability of non-invasive assessment of the pancreatic ducts, pancreatic parenchyma, neighbouring soft tissues, and vascular network in one examination. MRI can identify different characteristics of various solid pancreatic lesions, potentially allowing the differentiation of adenocarcinoma from other benign and malignant entities. In this review we describe the MRI protocols and MRI characteristics of various solid pancreatic lesions. Recognition of these characteristics may establish the right diagnosis or at least narrow the differential diagnosis, thus avoiding unnecessary tests or procedures and permitting better management.     

Roles of magnetic resonance imaging in management of bone tumors

The roles of magnetic resonance imaging (MRI) in the diagnosis and treatment of bone tumors are reviewed. Most bone tumors can be detected on plain radiography or bone scintigraphy. MRI is helpful in detecting tumors that do not destroy bone matrix or suppress reactive bone formation. Detailed analysis by plain radiography is still the most reliable method for differentiating between benign and malignant bone tumors. The T1 and T2 values, internal texture, and peritumoral edema depicted on MRI are not helpful for this differentiation. In characterizing the histologic types of bone tumors, MRI is of some advantage. For example, MRI can demonstrate cartilage matrix, hemoglobin metabolites, vascular components, and fat contents more clearly than conventional radiological techniques. MRI is now indispensable for the preoperative delineation of malignant bone tumors, because of its excellent soft tissue contrast and multiplanar imaging capability. In this article, the guidelines for evaluation of the surgical margin advocated by the JOA Musculo-skeletal Tumor Committee are introduced for radiologists. MRI monitoring of malignant bone tumors after chemotherapy or surgery can reveal change in the size of enhanced areas that may reflect viable tumors. Dynamic MRI is helpful to differentiate recurrent tumors from granulation tissue.     

Soft tissue tumors of the lower extremities

MRI is the preferred modality for th eevaluation of a soft tissue mass following radiography. The radiologic appearance of certain soft tissue tumors or tumor-like processes may be sufficiently unique to allow a strong presumptive radiologic diagnosis. It must be emphasized that one cannot differentiate reliably between benign and malignant lesions on radiologic imaging alone. When a specific diagnosis is not possible, knowledge of tumor prevalence by location and age, with appropriate clinical history and radiologic features, can be used to establish a suitably ordered differential diagnosis.     

MR Imaging of Soft Tissue Tumors: An Overview

Over the past decade, magnetic resonance (MR) imaging has been established as the most widely used examination for the detection of a suspected soft tissue mass and often for depiction of the extent and the characterization of the mass. Sensitivity of the examination for the detection of soft tissue masses is high but specificity is limited. With experience accrued over the past decade, radiologists are increasingly able to predict the histology of lesions based on MR imaging criteria. However, because of the overlap of morphologic features of benign and malignant soft tissue masses, a benign-appearing mass should not be considered benign unless the tumor can be specifically named and its histology predicted by well-established MR imaging features. When a mass is not thought to be an overt sarcoma and there is uncertainty as to whether it is benign or malignant, the tumor should be characterized as indeterminate and approached as a sarcoma until proven otherwise. This article reviews MR imaging in diagnosing and staging soft tissue masses and briefly discusses the radiologist?s approach to percutaneous biopsy of indeterminate soft tissue masses.     

Correlation between equivalent cross-relaxation rate and cellular density in soft tissue tumors

Objective

Equivalent cross-relaxation rate (ECR) imaging (ECRI), which allows quantitation of macromolecular tissue components, is a potentially useful nuclear magnetic resonance (NMR) technique for histopathological diagnosis. The purpose of this study was to compare ECR values among various histological types and assess the correlation between ECR and tumor cellular image in soft tissue tumors.

Materials and methods

We performed ECRI to evaluate cellular images of soft tissue tumors and tumorous lesions. Thirty-three patients who underwent evaluation with MRI and ECRI at the first visit were enrolled. Resection or biopsy was performed to obtain a histopathological diagnosis, followed by cell density measurement. ECR values of the histological subgroups were compared, and the correlation between ECR and cell density was analyzed to assess whether ECR can be used as an indicator of histological cell density.

Results

ECR values for benign tumors varied widely and were not significantly different from those for malignant tumors. However, the mean ECR value was significantly higher for high-grade malignant tumors than for low-grade tumors (p?<?0.01). Moreover, a positive correlation was found between ECR and cell density (r _s?=?0.72; p?<?0.01).

Conclusions

ECR reflects the cell density and malignancy grade of a soft tissue tumor. ECRI could provide cellular imaging and useful clinical information to aid the pre-operative diagnosis of soft tissue tumors.     

软组织肿块的MRI诊断价值

目的：探讨软组织肿块的MRI诊断价值。方法：回顾性分析43例经手术或穿刺活检病理证实的软组织肿块患者的MRI资料。结果：MRI能清晰显示出肿块的形态学改变及其范围，尤其对邻近结构受侵情况以及与神经血管柬的关系的显示较为敏感。部分有特异性形态及信号强度征象的肿块如脂肪瘤、血管瘤等依据其MRI可以明确诊断。良恶性两组肿块在大小、信号均匀性、边界及对周围结构的侵犯等方面差异无显著性意义（P〉0．05），其MRI特征有很大重叠性。MRI对软组织肿块潜在恶性评估的敏感性、特异性分别是66．67％、60％。结论：MRI对于发现肿块及显示病变所侵及的范围是最敏感、最准确的，对软组织肿块的诊断有很大的帮助，但在鉴别肿块良恶性方面的价值存在一定局限性。     

软组织神经源性肿瘤的MRI诊断

目的：评价ＭＲＩ对软组织神经源性肿瘤的诊断价值。材料与方法：回顾分析１３例软组织神经源性肿瘤的ＭＲＩ表现,其中良性神经源性肿瘤１０例,恶性３例,均经手术病理证实。结果：大部分肿瘤表现为卵圆形或梭形（ｎ＝１１）,边缘清晰（ｎ＝１１）,与邻近神经血管束关系密切（ｎ＝１２）。Ｔ１ＷＩ上均匀或轻度不均匀（ｎ＝９）,均为等于或稍高于肌肉信号。Ｔ２ＷＩ上为中等或明显不均匀（ｎ＝１０）高信号,仅１例神经纤维瘤于