Soft-tissue tumors: MR imaging

Development and Evaluation of MR-Based Radiogenomic Models to Differentiate Atypical Lipomatous Tumors from Lipomas

Background: The aim of this study was to develop and validate radiogenomic models to predict the MDM2 gene amplification status and differentiate between ALTs and lipomas on preoperative MR images. Methods: MR images were obtained in 257 patients diagnosed with ALTs (n = 65) or lipomas (n = 192) using histology and the MDM2 gene analysis as a reference standard. The protocols included T2-, T1-, and fat-suppressed contrast-enhanced T1-weighted sequences. Additionally, 50 patients were obtained from a different hospital for external testing. Radiomic features were selected using mRMR. Using repeated nested cross-validation, the machine-learning models were trained on radiomic features and demographic information. For comparison, the external test set was evaluated by three radiology residents and one attending radiologist. Results: A LASSO classifier trained on radiomic features from all sequences performed best, with an AUC of 0.88, 70% sensitivity, 81% specificity, and 76% accuracy. In comparison, the radiology residents achieved 60–70% accuracy, 55–80% sensitivity, and 63–77% specificity, while the attending radiologist achieved 90% accuracy, 96% sensitivity, and 87% specificity. Conclusion: A radiogenomic model combining features from multiple MR sequences showed the best performance in predicting the MDM2 gene amplification status. The model showed a higher accuracy compared to the radiology residents, though lower compared to the attending radiologist.

Soft Tissue Sarcomas

Imaging evaluation of soft tissue masses is essential for diagnosis, preoperative staging, and post-treatment follow-up. Magnetic resonance imaging plays the major role because of its superior resolution that helps in better tissue characterization, and its multiplanar imaging capability in evaluation of soft tissue masses. Additional imaging techniques, such as radiographs, computed tomography, positron-emission tomography-CT, radionuclide scintigraphy and ultrasonography, also play vital roles by providing additional information required in management of soft tissue masses. Knowledge of the usefulness and limitations of these imaging techniques is essential for their judicious selection. This article reviews the current role of various imaging techniques in diagnosis, presurgical planning, and post-treatment follow-up of soft tissue masses.

Tumor grade in soft-tissue sarcoma: Prediction with magnetic resonance imaging texture analysis

To determine the value of 3T magnetic resonance imaging (MRI) texture analysis in differentiating high- from low-grade soft-tissue sarcoma.Forty-two patients with soft-tissue sarcomas who underwent 3T MRI were analyzed. Qualitative and texture analysis were performed on T1-, T2- and fat-suppressed contrast-enhanced (CE) T1-weighted images. Various features of qualitative and texture analysis were compared between high- and low-grade sarcoma. Areas under the receiver operating characteristic curves (AUC) were calculated for texture features. Multivariate logistic regression analysis was used to analyze the value of qualitative and texture analysis.There were 11 low- and 31 high-grade sarcomas. Among qualitative features, signal intensity on T1-weighted images, tumor margin on T2-weighted images, tumor margin on fat-suppressed CE T1-weighted images and peritumoral enhancement were significantly different between high- and low-grade sarcomas. Among texture features, T2 mean, T1 SD, CE T1 skewness, CE T1 mean, CE T1 difference variance and CE T1 contrast were significantly different between high- and low-grade sarcomas. The AUCs of the above texture features were > 0.7: T2 mean, .710 (95% confidence interval [CI] .543-.876); CE T1 mean, .768 (.590-.947); T1 SD, .730 (.554-.906); CE T1 skewness, .751 (.586-.916); CE T1 difference variance, .721 (.536-.907); and CE T1 contrast, .727 (.530-.924). The multivariate logistic regression model of both qualitative and texture features had numerically higher AUC than those of only qualitative or texture features.Texture analysis at 3T MRI may provide additional diagnostic value to the qualitative MRI imaging features for the differentiation of high- and low-grade sarcomas.

The matrix environmental and cell mechanical properties regulate cell migration and contribute to the invasive phenotype of cancer cells

The minimal structural unit of a solid tumor is a single cell or a cellular compartment such as the nucleus. A closer look inside the cells reveals that there are functional compartments or even structural domains determining the overall properties of a cell such as the mechanical phenotype. The mechanical interaction of these living cells leads to the complex organization such as compartments, tissues and organs of organisms including mammals. In contrast to passive non-living materials, living cells actively respond to the mechanical perturbations occurring in their microenvironment during diseases such as fibrosis and cancer. The transformation of single cancer cells in highly aggressive and hence malignant cancer cells during malignant cancer progression encompasses the basement membrane crossing, the invasion of connective tissue, the stroma microenvironments and transbarrier migration, which all require the immediate interaction of the aggressive and invasive cancer cells with the surrounding extracellular matrix environment including normal embedded neighboring cells. All these steps of the metastatic pathway seem to involve mechanical interactions between cancer cells and their microenvironment. The pathology of cancer due to a broad heterogeneity of cancer types is still not fully understood. Hence it is necessary to reveal the signaling pathways such as mechanotransduction pathways that seem to be commonly involved in the development and establishment of the metastatic and mechanical phenotype in several carcinoma cells. We still do not know whether there exist distinct metastatic genes regulating the progression of tumors. These metastatic genes may then be activated either during the progression of cancer by themselves on their migration path or in earlier stages of oncogenesis through activated oncogenes or inactivated tumor suppressor genes, both of which promote the metastatic phenotype. In more detail, the adhesion of cancer cells to their surrounding stroma induces the generation of intracellular contraction forces that deform their microenvironments by alignment of fibers. The amplitude of these forces can adapt to the mechanical properties of the microenvironment. Moreover, the adhesion strength of cancer cells seems to determine whether a cancer cell is able to migrate through connective tissue or across barriers such as the basement membrane or endothelial cell linings of blood or lymph vessels in order to metastasize. In turn, exposure of adherent cancer cells to physical forces, such as shear flow in vessels or compression forces around tumors, reinforces cell adhesion, regulates cell contractility and restructures the ordering of the local stroma matrix that leads subsequently to secretion of crosslinking proteins or matrix degrading enzymes. Hence invasive cancer cells alter the mechanical properties of their microenvironment. From a mechanobiological point-of-view, the recognized physical signals are transduced into biochemical signaling events that guide cellular responses such as cancer progression after the malignant transition of cancer cells from an epithelial and non-motile phenotype to a mesenchymal and motile (invasive) phenotype providing cellular motility. This transition can also be described as the physical attempt to relate this cancer cell transitional behavior to a T1 phase transition such as the jamming to unjamming transition. During the invasion of cancer cells, cell adaptation occurs to mechanical alterations of the local stroma, such as enhanced stroma upon fibrosis, and therefore we need to uncover underlying mechano-coupling and mechano-regulating functional processes that reinforce the invasion of cancer cells. Moreover, these mechanisms may also be responsible for the awakening of dormant residual cancer cells within the microenvironment. Physicists were initially tempted to consider the steps of the cancer metastasis cascade as single events caused by a single mechanical alteration of the overall properties of the cancer cell. However, this general and simple view has been challenged by the finding that several mechanical properties of cancer cells and their microenvironment influence each other and continuously contribute to tumor growth and cancer progression. In addition, basement membrane crossing, cell invasion and transbarrier migration during cancer progression is explained in physical terms by applying physical principles on living cells regardless of their complexity and individual differences of cancer types. As a novel approach, the impact of the individual microenvironment surrounding cancer cells is also included. Moreover, new theories and models are still needed to understand why certain cancers are malignant and aggressive, while others stay still benign. However, due to the broad variety of cancer types, there may be various pathways solely suitable for specific cancer types and distinct steps in the process of cancer progression. In this review, physical concepts and hypotheses of cancer initiation and progression including cancer cell basement membrane crossing, invasion and transbarrier migration are presented and discussed from a biophysical point-of-view. In addition, the crosstalk between cancer cells and a chronically altered microenvironment, such as fibrosis, is discussed including the basic physical concepts of fibrosis and the cellular responses to mechanical stress caused by the mechanically altered microenvironment. Here, is highlighted how biophysical approaches, both experimentally and theoretically, have an impact on classical hallmarks of cancer and fibrosis and how they contribute to the understanding of the regulation of cancer and its progression by sensing and responding to the physical environmental properties through mechanotransduction processes. Finally, this review discusses various physical models of cell migration such as blebbing, nuclear piston, protrusive force and unjamming transition migration modes and how they contribute to cancer progression. Moreover, these cellular migration modes are influenced by microenvironmental perturbances such as fibrosis that can induce mechanical alterations in cancer cells, which in turn may impact the environment. Hence, the classical hallmarks of cancer need to be refined by including biomechanical properties of cells, cell clusters and tissues and their microenvironment to understand mechano-regulatory processes within cancer cells and the entire organism.

Soft tissue sarcoma: adding diffusion-weighted imaging improves MR imaging evaluation of tumor margin infiltration

PURPOSE

To determine the added value of diffusion-weighted imaging (DWI) to conventional magnetic resonance (MR) imaging in assessment of tumor margin infiltration in soft tissue sarcoma (STS) at 3T.

MATERIALS AND METHODS

The institutional review board approved this retrospective study. Forty-five patients who underwent 3T MR imaging including DWI and were pathologically confirmed were included in this study. Two readers retrospectively scored conventional MR imaging alone. Then, they assessed a combination of conventional MR imaging and DWI. At pathology, margin infiltration was retrospectively reviewed by one pathologist blinded to MR findings. Areas under the curve (AUCs) of the receiver-operating characteristic curve were obtained for diagnostic performance. Interobserver agreement for the scoring of margin infiltration of STS was assessed with kappa statistics.

RESULTS

Among 45 cases of STS, 33 had infiltrative tumor margin at pathology. Sensitivity, specificity, and accuracy of each reader were 100%, 17%, and 78%; 97%, 25%, and 78% on conventional MR imaging alone and 94%, 67%, and 87%; 94%, 42%, and 80% on conventional MR imaging combined with DWI. AUCs of conventional MR imaging combined with DWI were significantly higher than those of conventional MR imaging alone: 0.890 vs 0.678 (p = .0123) and 0.846 vs 0.640 (p = .0305) for each reader. Interobserver agreements of conventional MR imaging alone and conventional MR imaging combined with DWI were moderate to substantial (κ = 0.646, κ = 0.496).

CONCLUSION

The addition of DWI to conventional MR imaging may improve specificity for assessing tumor margin infiltration in STS at 3T.

KEY POINTS

• DWI has added value for assessment of tumor margin infiltration in soft tissue sarcoma. • Addition of DWI to conventional MRI at 3T may improve specificity. • Addition of DWI to conventional MRI may help orthopedic surgeon determine the extent of the resection margin.

Imaging appearances of soft-tissue tumors of the pediatric foot: review of a 15-year experience at a tertiary pediatric hospital

Tumors of the foot are rare in children. In this review the authors illustrate radiographic, sonographic and MR imaging findings of foot soft-tissue tumors in children based on all cases presenting at a tertiary pediatric hospital during the 15-year period of 1999-2014. Among these cases there were 155 tumors of the foot - 72 of the bones and 83 of the soft tissues. Vascular malformations, fibromatosis and sarcomas were respectively the most frequent benign, intermediate and malignant soft-tissue tumors. Some tumors showed specific imaging findings. In imaging investigations, ultrasound can be used as the first imaging modality for diagnostic workup of most lesions because it is noninvasive, low-cost and readily available, and can confirm the presence of the mass and evaluate cystic components, especially in young children who would otherwise require sedation for MR imaging. MR imaging is the reference standard technique because of its high tissue contrast, which allows for detection and characterization of soft-tissue and bone abnormalities. MR imaging is useful as the first imaging modality in select cases, including those with high suspicion of malignancy, very large lesions or pre-treatment lesions. Recognition of some typical imaging findings in pediatric soft-tissue foot tumors is helpful to establish diagnosis and facilitate patient management.

Retrospective study using MRI to measure depths of acupuncture points in neck and shoulder region

OBJECTIVES

There are safety issues associated with acupuncture treatment. Previous studies regarding needling depth of acupuncture points revealed inconsistent results due to vague depth definition, acupuncture point localisation and measuring tools. The objective of this study is to find and compare the differences of the mean depths of 11 acupuncture points in the neck and shoulder region between subjects, with variables including gender and body mass index (BMI).

SETTING

This study was conducted at a single medical center in Taiwan.

PARTICIPANTS

Three hundred and ninety-four participants were included in this study. Participants were grouped according to gender and BMI. Acupuncture points were localised by WHO standard and measured by MRI.

OUTCOME MEASURES

The distance from the needle insertion point (surface of the skin) to any tissues that would cause possible/severe complications.

RESULTS

Mean depths of 11 points were obtained in groups of different BMI and gender. Mean depths of all participants regardless of BMI and gender are as follows, in centimetres: GB21=5.6, SI14=5.2, SI15=8.8, GV15=4.9, GV16=4.6, GB20=5.0, ST9=1.6, SI16=1.8, SI17=2.4, TE16=3.1, LI18=1.3. Participants with higher BMI had greater measured depths in both gender groups. Male participants had larger mean depths than female participants regardless of BMI except in SI17 and LI18. When taking BMI into consideration, depths in male participants are greater than in female participants in most of the points except the following: GB21, TE16 in obesity group; ST9 in underweight and obesity group; SI16 in ideal body weight, overweight and obesity group; SI17, LI18 in each group.

CONCLUSIONS

Participants with higher BMI had greater measured depths and males tended to have greater depths in most of the points. Clinical practitioners are recommended to consider this information to prevent complications when applying acupuncture treatment to their patients.

Treatment for intramuscular lipoma frequently confused with sarcoma: a 6-year restrospective study and literature review

Introduction. Intramuscular lipoma is a very rare form of lipoma, known to be categorized as an infiltrating lipoma due to its tendencies to infiltrate the muscle or the synovium. Contrary to other subcutaneous lipomas, even after surgical removal, the rate of local recurrence ranges at a high rate from 50∼80% and differential diagnosis with liposarcoma is very difficult. Patients and Methods. A retrospective chart review was conducted for a total of 27 patients. Before performing a surgery based on the types of mass, a radiologic imaging study was performed. An intraoperative frozen biopsy was performed on every patient and the results were compared. The progress was monitored every 3 to 6 months for recurrence or struggles with rehabilitation. Results. There were 13 male and 14 female patients with an average age of 54.6. The average tumor size was 8.2 cm (1.1 cm∼31.6 cm). Excision was performed using a wide excision. All 27 individuals were initially diagnosed as intramuscular lipoma; however, 1 of the patients was rediagnosed as liposarcoma in the final checkup. The patients had an average of 3 years and 1 month of follow-up and did not suffer recurrences. Conclusion. Thus, it is essential that a frozen biopsy is performed during the surgery in order to identify its malignancy. And a wide excision like malignant tumor operation is a principle of treatment.

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.

Unusual intramuscular lipoma of deltoid muscle

Lipomas are common soft tissue tumors usually located under the skin. Nevertheless, intramuscular lipomas of deltoid muscle are unusual tumors. We present a case of 74-year-old woman with an intramuscular like clepsydra lipoma of deltoid muscle. The lesion was a palpable soft mass at the lateral side of the humerus. The patient had no previous history of trauma. The main symptom was pain only in abduction and extension. Imaging, pathological findings and surgical excision are discussed.

Soft-tissue masses and masslike conditions: what does CT add to diagnosis and management?

OBJECTIVE

Although MRI is the technique of choice for evaluating most soft-tissue masses, CT often provides valuable complementary information. Specifically, there are distinguishing CT characteristics that can suggest a specific diagnosis, including the lesion's mineralization pattern, density, pattern of adjacent bone involvement, and degree and pattern of vascularity.

CONCLUSION

This article provides an overview of the CT evaluation of soft-tissue masses, emphasizing a differential diagnosis based on these CT features.

Mandibular invasion of squamous cell carcinoma: factors determining surgical resection of mandible using computerized tomography and histopathologic study

AIM

Carcinoma of the mandibular region can be considered as an important, distinct entity associated with special problems relating to diagnosis, evaluation of extension, planning of treatment, surgical techniques, treatment result and prognosis. The study was aimed to assess the accuracy of computerized tomography in demonstrating mandibular invasion, to assess the role of anatomic structures like cancellous spaces, the inferior alveolar nerve and periodontal spaces in spread of carcinomas in the mandible and to determine the spread of tumour within the mandible and the resection procedure to be carried.

MATERIALS AND METHODS

11 mandibular specimens which were resected for squamous cell carcinoma were examined clinically, radiographically and histopathologically. Computerized tomography 120 KV, 40 to 130ma, obtaining slices starting from the center of lesion to the clearance, of the bone involvement distally and proximal to the lesion with excellent soft tissue or cortical bone interface with bone enhancement mode was used as a principle investigating tool to assess the tumour penetration in the mandible which was confirmed by histopathologic sections.

RESULTS

A conditional probability test was conducted according to Bayes' theorem, and the results showed sensitivity 60% and specificity 77.8%, a false negative rate 40% and false positive rate 22.2%. A positive predictive value 69% and negative predicative value 70%.

CONCLUSION

In our study the factors to be taken into consideration in deciding the type of resection are the pattern of tumour infiltration, irradiated or non irradiated mandibles, presence or absence of dentition, the inferior alveolar nerve involvement and the periodontal space involvement. The computerized tomography has a significant role in detecting the involvement of tumour in the mandible with enhanced settings.

Computed tomographic, magnetic resonance imaging, and cross-sectional anatomic features of the manus in cadavers of dogs without forelimb disease

OBJECTIVE-To provide a detailed description of cross-sectional anatomic structures of the manus in canine cadavers in association with corresponding features in computed tomographic (CT) and magnetic resonance (MR) images. SAMPLE POPULATION-7 cadavers of adult large-breed-type dogs (weight range, 25 to 30 kg) without forelimb disease. PROCEDURES-Forelimbs were removed from the cadavers within 4 hours after euthanasia and frozen. The right forelimbs of 3 cadavers were cut into 4-mm sections by use of a band saw; 1 limb each was sectioned in the transverse, dorsal, or sagittal plane. Sections were cleaned and then photographed. After thawing, transverse CT images of the right forelimbs of 3 additional cadavers were obtained, and the right forelimb of a seventh cadaver underwent MR imaging in the transverse, sagittal, and dorsal planes. The evaluated regions extended from the digits to the carpus. Features in CT and MR images that corresponded to clinically important anatomic structures in tissue sections were identified. RESULTS-For most of the anatomic structures evident in tissue sections, corresponding CT and MR imaging features were identified. Osseous and musculotendinous structures of the manus were readily detected in CT and MR images, whereas vascular structures were only rarely identified by use of the imaging techniques. CONCLUSIONS AND CLINICAL RELEVANCE-Results of the detailed assessment of anatomic structures of the canine manus in association with corresponding features in CT and MR images will facilitate detection of pathological conditions and be beneficial in planning surgical procedures for diseases of the manus in dogs.

Espectroscopia de prótons e perfusão por ressonância magnética na avaliação dos tumores do sistema musculoesquelético

OBJETIVO: Avaliar a espectroscopia de prótons e o estudo dinâmico do contraste por ressonância magnética na diferenciação dos tumores musculoesqueléticos benignos e malignos. MATERIAIS E MÉTODOS: Foram estudados 55 pacientes com tumores musculoesqueléticos (27 malignos e 28 benignos). Os exames foram realizados em aparelho de ressonância magnética de 1.5 T com protocolo convencional e espectroscopia de prótons com TE de 135 ms. O estudo dinâmico do contraste foi adquirido pela sequência T1 gradiente-eco após a administração intravenosa de gadolínio. Curvas de intensidade de sinal versus tempo e valores de slope foram calculados. A análise estatística foi realizada pelo teste de Levene, seguido pelo teste t de Student, além dos testes qui-quadrado de Pearson e exato de Fischer. RESULTADOS: A sensibilidade, especificidade e acurácia da espectroscopia de prótons foram, respectivamente, de 87,5%, 92,3% e 90,9% (p < 0,0001). Além disso, houve significativa diferença entre o valor quantitativo da curva entre as lesões benignas (média de 27,5% por minuto) e malignas (média de 110,9% por minuto) (p < 0,0001). CONCLUSÃO: Os estudos quantitativo e qualitativo da análise dinâmica do contraste por ressonância magnética associados à presença do pico de colina são úteis na diferenciação dos tumores musculoesqueléticos em benignos e malignos.

Special problems encountering surgical management of large retroperitoneal schwannomas

Background

Retroperitoneal schwannomas are rare, usually benign tumors that originate in the neural sheath and account for only a small percentage of retroperitoneal tumors. The aim of this clinical study is to present our experience in managing retroperitoneal schwannomas with a review of the current literature and to point out the surgical technical difficulties we faced, due to the tumor's strange behavior that eroded the vertebra in two cases without causing malignant invasion.

Methods

We reviewed the medical files of 69 patients treated in our department for retroperitoneal tumors from January 1991 until December 2006. Five patients had retroperitoneal schwannomas according to pathology report.

Results

There were two male and three female patients, with a mean age of 56 years (range 44–67 years). All patients were asymptomatic and none suffered from von Recklinghausen disease. Imaging workup included ultrasonography, computed tomography and magnetic resonance imaging. One patient, after having a non-diagnostic computed tomography fine needle aspiration (CT-FNA), underwent exploratory laparotomy and incisional biopsy that established the diagnosis of schwannoma. After complete excision of the tumors, postoperative course was uneventful in all patients. Tumors' maximum diameter was 12.7 cm (range 7–20 cm). No recurrences were detected during the follow up period (6–75 months).

Conclusion

Preoperative establishment of diagnosis is difficult in case of retroperitoneal schwannomas, however close relationship of retroperitoneal tumors with adjacent neural structures in imaging studies should raise a suspicion. Complete surgical resection is the treatment of choice. Histology and Immunohistochemistry confirms the diagnosis.

Mazabraud's syndrome coexisting with a uterine tumor resembling an ovarian sex cord tumor (UTROSCT): a case report

The association of intramuscular myxoma and fibrous dysplasia is a rare disease known as Mazabraud's syndrome. We present a case of Mazabraud's syndrome coexisting with a uterine tumor and resembling an ovarian sex cord tumor (UTROSCT). This uterine tumor showed a high mitotic index and cytological atypia. To the best of our knowledge, the coexistence of the two different entities has not been reported in the literature.

The value of magnetic resonance imaging in the differentiation between malignant peripheral nerve-sheath tumors and non-neurogenic malignant soft-tissue tumors

OBJECTIVE

To assess the sensitivity and specificity of MRI criteria in the differentiation between malignant peripheral nerve sheath tumors (MPNST) and non-neurogenic malignant soft-tissue tumors (MSTT).

DESIGN AND PATIENTS

MRI examinations of 105 patients with pathologically proven malignant soft-tissue lesions (35 MPNST and 70 MSTT) were retrospectively reviewed, the reviewers being unaware of the pathological diagnosis. Using a standardized protocol, the tumors were evaluated for multiple parameters regarding morphology and appearance on different sequences before and after gadolinium contrast administration (location, distribution, delineation, homogeneity, size, shape, relationship to bone and neurovascular bundle, intralesional hemorrhage, necrosis, perilesional edema, lymphangitis and signal intensities). Results were compared using a chi-square or Fisher's exact test.

RESULTS

MRI findings suggestive of MPNST (p<0,05) were intermuscular distribution, location on the course of a large nerve, nodular morphology, and overall non-homogeneity on T1-weighted images, T2-weighted images and T1-weighted images after gadolinium contrast injection. MRI findings in favor of MSTT were intramuscular distribution, ill-delineated appearance of more than 20% of the lesion's circumference, and presence of intralesional blood vessels, perilesional edema and lymphangitis. There is no significant difference for degree and pattern of enhancement after gadolinium contrast injection, nor for presence of bone involvement or cystic or necrotic areas.

CONCLUSION

MRI provides several features that contribute to the differentiation between MPNST and non-neurogenic malignant soft-tissue tumors. MRI findings suggestive of MPNST should be helpful to pathologists in the strategy for further examination.

MRI detection of early bone metastases in b16 mouse melanoma models

Bone metastasis causes significant morbidity in cancer patients, including bone pain, pathologic fractures, nerve compression syndrome, and hypercalcemia. Animal models are utilized to study the pathogenesis of skeletal metastases and to evaluate potential therapeutic agents. Previously published methods for imaging bone metastasis in rodent models have focused on identifying advanced stage metastasis using simple X-rays. Here we report MRI as a method for detecting early bone metastases in mouse models in vivo. B16 mouse melanoma cells were injected into the left cardiac ventricle of C57BL/6 mice and magnetic resonance (MR) images were obtained of the left leg following the development of metastatic disease, when tumor associated bone destruction was histologically present but not visible by X-ray. T1 and T2 relaxation times of bone marrow were measured in healthy control mice and B16 melanoma tumor-bearing mice. Mean T2 values for normal marrow were 28 ms (SD 5) and for diseased bone marrow were 41 ms (SD 3). T2 relaxation time of diseased bone marrow is significantly longer than that of normal bone marrow (P < 0.0001) and can be used as a marker of early bone metastases. These studies demonstrate that MR imaging can detect bone marrow metastases in small animals prior to development of cortical bone loss identified by X-ray.

Soft-tissue masses

The purpose of this study was to show the qualitative and quantitative MRI characteristics of soft-tissue masses in differentiation of benign and malignant lesions. A total of 90 soft-tissue lesions were reviewed in this study. The scoring system presents a more objective diagnostic performance in the prediction of benign or malignant masses. With the use of this scoring system, unnecessary biopsy can be precluded in benign lesions.

Dynamic contrast-enhanced perfusion MR imaging of diseased vertebrae: analysis of three parameters and the distribution of the time-intensity curve patterns

OBJECTIVE

To assess the diagnostic value of perfusion MR imaging of diseased vertebrae by analysis of three parameters and the distribution of the time-intensity curve (TIC) patterns.

DESIGN AND PATIENTS

Dynamic MR imaging was performed on 34 patients with 48 lesions. All lesions were assigned to one of four groups: osteoporotic compression fracture, benign lesion without compression fracture, pathologic compression fracture, or metastatic lesion without fracture. Peak enhancement, steepest slope, and slope value were calculated from the TIC of diseased vertebrae. TICs were classified into five types. Comparisons were made among groups by analysis of the three parameters and the distributions of the TICs pattern.

RESULT

All parameters of pathologic compression fracture were significantly higher than those of osteoporotic compression fracture (P<0.05). The steepest slopes of metastatic lesions with and without pathologic compression fracture were significantly higher than those of benign lesions without compression fracture (P<0.05). No characteristic distribution of the TIC pattern helpful for the differentiation of benign and metastatic lesions was found.

CONCLUSION

In distinguishing osteoporotic from pathologic compression fractures, semiquantitative analysis of the perfusion MR imaging may be useful. However, the analysis of the TIC patterns can not significantly contribute to the differential diagnosis.

Magnetic resonance imaging of intramuscular myxoma with histological comparison and a review of the literature

OBJECTIVE

To evaluate the magnetic resonance (MR) features of intramuscular myxoma (IM) compared with its pathological findings.

DESIGN

Two radiologists retrospectively reviewed records and imaging studies of patients with histologically proven IM. Two radiologists also analyzed by consensus all the MR studies (pre- and post-contrast T1-weighted and T2-weighted sequences) and a pathologist reviewed the available histological material.

PATIENTS

Seventeen patients with 18 histologically proven IM were reviewed. Histological samples of 11 of these 18 tumors were available for pathological analysis.

RESULTS

There were 14 women and three men, with a mean age of 58.9 years. IM involved predominantly the thigh (n=10). MR imaging showed well-circumscribed intramuscular masses, hypointense on T1-weighted and hyperintense on T2-weighted images. Eleven masses were homogeneous and seven slightly heterogeneous due to fibrous septa. Enhanced MR imaging demonstrated three different patterns: peripheral enhancement (n=1), peripheral and patchy internal enhancement (n=7) or peripheral and linear internal enhancement (n=4). Intratumoral cysts were detected in four masses. MR imaging showed the presence of a pseudocapsule (n=12), fat around the lesion (n=16) and peritumoral edema (n=16). Histologically, all the tumors were hypocellular, hypovascular and myxoid. Peripheral areas of collagenous fibers formed a partial capsule and IM often merged into surrounding muscular fibers. More cellular tumors and those with scanty myxoid stroma tended to show a more prominent internal enhancement.

CONCLUSION

IM shows several recognizable MR features which suggest its diagnosis.

Soft-Tissue Tumors: Value of Static and Dynamic Gadopentetate Dimeglumine–enhanced MR Imaging in Prediction of Malignancy

PURPOSE

To prospectively evaluate static and dynamic gadopentetate dimeglumine-enhanced magnetic resonance (MR) imaging relative to nonenhanced MR imaging in differentiation of benign from malignant soft-tissue lesions and to evaluate which MR imaging parameters are most predictive of malignancy, with associated interobserver variability.

MATERIALS AND METHODS

One hundred forty consecutive patients (78 male patients [median age, 51 years], 62 female patients [median age, 53 years]) with a soft-tissue mass underwent nonenhanced static and dynamic contrast material-enhanced MR imaging. Diagnosis was based on histologic findings in surgical specimens (86 of 140), findings at core-needle biopsy (43 of 140), or results of all imaging procedures with clinical follow-up (11 of 140). Multivariate logistic regression analysis was used to identify the best combination of MR imaging parameters that might be predictive of malignancy. Subjective overall performance of two observers was evaluated with receiver operating characteristic analysis.

RESULTS

For subjective overall diagnosis, area under the receiver operating characteristic curve, a measure for diagnostic accuracy, was significantly larger for combined nonenhanced and contrast-enhanced MR imaging than it was for nonenhanced MR imaging alone, with no significant difference between observers. Multivariate analysis of all lesions revealed that combined nonenhanced static and dynamic contrast-enhanced MR imaging parameters were significantly superior to nonenhanced MR imaging parameters alone and to nonenhanced MR imaging parameters combined with static contrast-enhanced MR imaging parameters in prediction of malignancy. The most discriminating parameters were presence of liquefaction, start of dynamic enhancement (time interval between start of arterial and tumor enhancement), and lesion size (diameter). Results for extremity lesions were the same, with one exception: With dynamic contrast-enhanced MR imaging parameters, diagnostic performance of one observer did not improve.

CONCLUSION

Static and dynamic contrast-enhanced MR imaging, when added to nonenhanced MR imaging, improved differentiation between benign and malignant soft-tissue lesions.

Characterization of Bone and Soft-Tissue Tumors with in Vivo1H MR Spectroscopy: Initial Results

PURPOSE

To determine if in vivo detection of choline by using hydrogen 1 (1H) magnetic resonance (MR) spectroscopy with dynamic contrast material-enhanced MR imaging can help differentiate between benign and malignant musculoskeletal tumors.

MATERIALS AND METHODS

MR imaging was performed in 36 consecutive patients with bone and soft-tissue tumors larger than 1.5 cm in diameter. Examinations were performed at 1.5 T with a surface coil appropriate for the location of the lesions. Single-voxel 1H MR spectroscopy was performed by using a point-resolved spectroscopic sequence with echo times of 40, 135, and 270 msec. The volume of interest within lesions was positioned on the areas of early enhancement (<8 seconds after arterial enhancement) according to the findings of dynamic contrast-enhanced MR imaging with subtraction. The criterion for determining whether choline was present in a lesion was a clearly identifiable peak at 3.2 ppm in at least two of the three spectra acquired at echo times. MR spectroscopic results and histopathologic findings were determined in blinded fashion and compared with kappa statistics. P <.001 was considered to indicate a significant difference.

RESULTS

Choline was detected in 18 of 19 patients with malignant tumors and in three of 17 patients with benign lesions. The three benign lesions included one perineurioma, one giant cell tumor, and one abscess. Choline was not detected in 14 patients with benign lesions nor in one patient with a densely ossifying low-grade parosteal osteosarcoma. In vivo 1H MR spectroscopy characterized bone and soft-tissue tumors, resulting in a sensitivity of 95%, specificity of 82%, and accuracy of 89% (P <.001).

CONCLUSION

Choline can be reliably detected in large malignant bone and soft-tissue tumors by using a multiecho point-resolved spectroscopic protocol. 1H MR spectroscopy can help differentiate malignant from benign musculoskeletal tumors by revealing the presence or absence of water-soluble choline metabolites.

MR findings of clear cell sarcoma: two case reports

We report two patients with clear cell sarcomas arising from tendons in the ankle and knee. In the current cases, calcifications, fluid-fluid levels and the marked hypointense areas are not seen within the masses. In the differential diagnosis of the mass developing in the tendons and aponeuroses, when these signs are absent, the probability of clear cell sarcoma is higher.

Magnetic resonance imaging of soft-tissue tumors in children

Magnetic resonance imaging (MRI) has become an important diagnostic tool in the detection and characterization and local anatomic staging of soft-tissue tumors in children. This article outlines some of the procedural issues unique to the pediatric population.

The management of retroperitoneal soft tissue sarcoma: a single institution experience with a review of the literature

AIM

Ten percent of soft tissue sarcomas (STS) arise in the retroperitoneal tissues. The prognosis for patients with retroperitoneal sarcoma is poor with a 5-year survival rate between 12% and 70%. Stage at presentation, high histological grade, unresectable primary tumour and incomplete resection are associated with a less favourable outcome.

METHODS

Complete follow-up data were available on 22 patients who underwent surgery for retroperitoneal STS in our institution between 1990 and 2000. Patient, tumour and treatment variables were analysed including use of adjuvant therapy and survival status.

RESULTS

Eighteen patients underwent surgery for primary disease, four patients were treated for recurrent disease or metastases. Ten patients presented with pain, seven with an abdominal mass, other presentation included weight loss and haematuria. Thirteen patients presented with tumours larger than 10 cm. The tumours were seven liposarcomas, six leiomyosarcomas, three malignant fibrous histiocytomas, two rhabdomyosarcomas, two malignant schwannomas and two undifferentiated sarcomas. Six primary tumours were completely excised, five patients received radiotherapy and five received chemotherapy. Local recurrence rate was 45% and recurrence-free interval for 10 patients with recurrence was 11 months. Five patients received radiotherapy and five received chemotherapy. The median survival for patients with primary tumours was 36 months, and 5-year survival was 44%. Adjuvant therapy was not associated with higher survival rates.

CONCLUSION

This study re-emphasizes the poor outcome of patients with retroperitoneal STS. Adjuvant radiotherapy and chemotherapy do not appear to be any proven benefit and the single most important prognostic factor is aggressive successful en bloc resection of the primary tumour. Our resection rate and 5-year survival rates are comparable with previous reported UK series although lower than large reports from North American centres. This might partly be explained by difficulty in data collection in a retrospective analysis, but may reflect inadequate subspecialization in UK centres.

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.

Metastatic non-small cell lung carcinoma with involvement of extremity musculature: case report and review of the literature

Hematogenous dissemination of non-small cell lung carcinoma (NSCLC) metastatic to skeletal musculature in the absence of osseous involvement is an infrequent occurrence. We retrospectively reviewed our institution's indexed database for patients evaluated from 1975 through 1997 who were diagnosed as having skeletal musculature metastases from NSCLC. Eight men and 2 women were identified (age range, 51-80 years at time of metastases). Four primary adenocarcinomas, 4 primary lung squamous cell carcinomas (SCCs), and 2 poorly differentiated primary NSCLCs were identified. Approximate tumor sizes ranged from 10 cm3 to 288 cm3. External-beam radiation therapy was used in 7 of 10 cases; complete surgical excision was performed in 3 cases. Patients with known neoplasm who have extremity pain and negative findings on bone scan should be evaluated for soft tissue tumor involvement because such findings significantly affect clinical management. One case of lung SCC metastatic to the quadratus femoris muscle in a 63-year-old man is discussed in detail.

Soft-tissue venous malformations in pediatric and young adult patients: diagnosis with Doppler US

PURPOSE

To describe the diagnostic features, appearance, and vascularization pattern of venous malformations (VMs) at Doppler ultrasonography (US).

MATERIALS AND METHODS

Between February 1991 and May 1997, 51 soft-tissue VMs were studied with Doppler US in patients between 1 day and 21 years of age (mean age, 9 years). These VMs were located in the maxillofacial region (n = 19), trunk (n = 5), and upper (n = 10) and lower (n = 17) extremities. Twenty-three VMs had venographic confirmation, seven had only histologic confirmation, and 21 had both venographic and histologic confirmation. US was performed with 7.5- or 7-10-MHz linear transducers, a low pulse repetition frequency (mean, 1,680 Hz), and the lowest wall filter (25-50 Hz).

RESULTS

At gray-scale US, VMs appeared as hypoechoic, heterogeneous lesions in 82% of cases. All lesions displayed compressibility. In eight lesions (16%), phleboliths were identified, thus confirming the diagnosis of VM. Analysis of vascular flow revealed monophasic, low-velocity flow in 40 VMs (78%), with an average flow velocity of 0.22 kHz. Biphasic flow was noted at the periphery of three lesions, which is indicative of a mixed capillary-venous malformation. The remaining eight lesions did not display any flow.

CONCLUSION

In pediatric patients, Doppler US is a noninvasive, easily available, and rapid mode of investigation of vascular lesions and can help confirm the diagnosis of VM when it shows a characteristic flow pattern.

Solitary cellular schwannoma (neurilemmoma) showing malignant changes: evaluation through magnetic resonance imaging (M.R.I.), surgical intervention, and histopathology

Schwannoma (neurilemmoma) are common benign tumors arising from the peripheral nerve sheath. Malignant transformation is uncommon. A unique case showing such a transformation is reported highlighting the roles of magnetic resonance imaging, surgical intervention, and histopathology. The case was thoroughly investigated by learning the details of the sequence of events leading to the current status. The evaluation was made through magnetic resonance imaging. In addition, computed tomography and conventional radiography were used to locate any foci of calcification. Subsequently, the tumor's gross and microscopic morphology was defined by surgical intervention and histopathology. Malignant schwannoma of the left leg occupying the entire calf is extremely uncommon. Only ten cases have been reported thus far, including the current one from the Indian subcontinent. Malignant transformation in a schwannoma differs significantly from malignant nerve sheath tumors (erroneously called malignant schwannomas). An endeavour has been made to differentiate malignant transformation in schwannoma from other malignant peripheral nerve sheath tumors. An innovation in this direction is magnetic resonance imaging. This investigate procedure is imperative in such situations, along with surgery and histopathology, which may also help in classifying the condition.

Magnetic resonance imaging of the musculoskeletal system. Part 9. Primary Tumors

Magnetic resonance imaging, because of its exquisite soft tissue contrast, has dramatically improved the ability to preoperatively stage primary osseous and soft tissue neoplasms. This technique also has allowed the monitoring of the effects of chemotherapy and the screening for recurrence of neoplasms. The role of magnetic resonance imaging in the preoperative evaluation of the patient with a suspected primary osseous or soft tissue neoplasm is outlined, instances where magnetic resonance imaging potentially may make a specific diagnosis are outlined, the importance of gadolinium enhancement as an adjunct to native magnetic resonance imaging is stressed, and an algorithm for followup of patients after chemotherapy or definitive surgical treatment is presented. In all cases, the magnetic resonance images should be correlated with the plain film, which is still an important aspect of the diagnosis of osseous lesions.

Practical considerations in the imaging of soft tissue tumors

Cost-effective imaging evaluation of a suspected soft tissue tumor requires knowledge of all available imaging modalities, including indications for each and relative advantages and disadvantages. Imaging studies are useful in pre-treatment diagnostic evaluation, biopsy planning, and post-treatment evaluation for recurrence. Close communication between the orthopedic surgeon and radiologist is essential for appropriate management. This article will emphasize an approach to the imaging evaluation of a suspected soft tissue tumor.

Orthopedic soft-tissue tumors. Concepts for the primary care physician

Mesenchymal neoplasia includes an extensive variety of tumors. It is important that the primary care physician understand the different qualities of benign and malignant processes in incidence, pathogenesis, history, physical findings, and diagnostic work-up and, as a result, be able to make the appropriate orthopedic consultation when necessary. It also is important that they understand basic concepts of definitive treatment so that they may educate their patients. Table 2 lists some of the more common benign and malignant soft-tissue tumors. It is by no means an attempt to be inclusive, but rather to serve as an introduction to a vast group of neoplasms.

Magnetic resonance imaging of the musculoskeletal system. II. The hip

Magnetic resonance (MR) imaging of the hip joint and adjacent structures can provide valuable information under many clinical circumstances. After plain radiography, MR imaging is arguably the modality of choice for the detection of osteonecrosis, occult fractures, primary and secondary neoplasms, and in the assessment of some soft tissue abnormalities. The accuracy of MR imaging is dependent on technical factors, such as magnet field strength, surface coils, and sequence selection. Low resolution MR images generally are satisfactory for screening for osteonecrosis and for the evaluation of large bone or soft tissue abnormalities. Tailoring an examination with high resolution images, specialized sequences, or contrast may add useful information, particularly if a detailed evaluation of the joint is desired. Tailoring of the examination by an experienced radiologist requires adequate clinical information, so communication between the referring physician and radiologist is crucial for optimal results. Finally, MR imaging and radiographs are complementary examinations; MR images of the hip should not be interpreted without having recent radiographs available for comparison.