Muscle Sarcoma Research Articles

Head and neck embryonal rhabdomyosarcoma clinical outcomes determinates: A pooled database analysis.

e23537 Background: Embryonal rhabdomyosarcoma (ERS) is a soft tissue sarcoma of skeletal muscle with mesenchymal precursor cells that involve the genitourinary system or head and neck. Currently, head and neck embryonal rhabdomyosarcoma (HNERS) is considered a similar entity to other ERS subtypes by the Intergroup Rhabdomyosarcoma Study Group (IRSG), with only parameningeal disease being considered as high risk. We seek to identify other higher risk phenotypes in this population. Methods: To study the demographic, molecular and IHC characteristics, therapeutic interventions, survival, and prognostic factors, we compiled a pooled database of 101 cases of HNERS. Kaplan-Meier survival curves, Cox proportional-hazards model and Log-rank tests were used to assess the influence of demographic and clinicopathologic factors on overall survival (OS). Results: 101 patients with confirmed HNERS were identified: median age of 6.5 years, male predominance with M:F ratio of 1.7. While R0 was achieved in 44%, surgical R1 and R2 were feasible in 13% and 44% of the cases. HNERS involved the following anatomic sites: Parameningeal (49%), Skull (40%), Maxilla (39%), Nasopharynx (34%), Ears (25%), Oropharynx (17%), Nervous system (16%), Larynx (14%), Mandible (12%), Internal Jugular (7%), Orbit and Carotids (6% each), Tongue (3%), and thyroid (2%). Lymph nodes, and bone marrow were involved in 11% and 2%, respectively. Metastases occurred in 4%. The stage distribution consisted of stage I (41%), stage II (34%), stage III (19%), and stage IV (6%). Clinical groups comprised: IA(23%), IB(4%), IIA(8%), IIB(3%), IIIA(45%), IIIB(12%), and IVA(4%). Risk groups consisted of low (53%), intermediate (41%), and high (6%). The cohort’s median DFS was 240 months whereas the median OS was not reached. OS was negatively affected by parameningeal (p = 0.01), nasopharyngeal (p = 0.02), ear (p = 0.02), nerve (p = 0.0001), bone (p = 0.002), and LN (p = 0.0004) involvement. The presence of metastases was associated with worse OS (p = 0.0001). The IRSG staging system (p < 0.0001), the risk groupings (p = 0.0001), and the clinical groupings (p = 0.06) correlated with OS, though the latter did not reach statistical significance. Compared to no treatment, localized therapies such as surgery and radiation therapy, and combination chemotherapy had statistically significant improvement in OS (p = 0.027). Achieving CR was associated with superior OS (p < 0.0001). OS wasn't impacted by age, sex, extent of surgery, IHC, BM involvement or other head and neck anatomic site involvement. Conclusions: Embryonal Rhabdomyosarcoma of the Head and Neck is a distinct clinical subtype of ERS not fully defined by IRSG clinical groups when compared to other types of embryonal rhabdomyosarcoma. Parameningeal, nasopharyngeal, ear involvement had poor OS and should be considered as a clinical grouping. This study presents updated data from a pooled cohort of patients with HNERS.

Radiation-Induced Right Pectoralis Muscle Sarcoma after Breast Cancer: Case Report and Review of the Literature

Radiation-induced sarcoma of the breast is a rare but serious complication of radiation therapy for breast cancer. Although the risk of this complication is low, patients who have undergone radiation therapy for breast cancer should have regular follow-up to detect any signs of new tumor or recurrence. Imaging tests such as CT or MRI can be used to screen for radiation-induced sarcoma. If radiation-induced sarcoma is detected, the recommended treatment includes complete surgical removal followed by postoperative radiation therapy.

SIX1 reprograms myogenic transcription factors to maintain the rhabdomyosarcoma undifferentiated state.

SUMMARYRhabdomyosarcoma (RMS) is a pediatric muscle sarcoma characterized by expression of the myogenic line-age transcription factors (TFs) MYOD1 and MYOG. Despite high expression of these TFs, RMS cells fail to terminally differentiate, suggesting the presence of factors that alter their functions. Here, we demonstrate that the developmental TF SIX1 is highly expressed in RMS and critical for maintaining a muscle progenitor-like state. SIX1 loss induces differentiation of RMS cells into myotube-like cells and impedes tumor growth in vivo. We show that SIX1 maintains the RMS undifferentiated state by controlling enhancer activity and MYOD1 occupancy at loci more permissive to tumor growth over muscle differentiation. Finally, we demonstrate that a gene signature derived from SIX1 loss correlates with differentiation status and predicts RMS progression in human disease. Our findings demonstrate a master regulatory role of SIX1 in repression of RMS differentiation via genome-wide alterations in MYOD1 and MYOG-mediated transcription.

Primary leiomyosarcoma of the great saphenous vein: A case report.

Introduction and importanceVascular smooth muscle sarcomas are rare neoplasms that comprise less than 2% of all leiomyosarcomas. These malignancies usually originate in the inferior vena cava, with a limited number of cases affecting the great saphenous vein. Due to the limited reports on these sarcomas, epidemiologic data remains insufficient.Case presentationWe report the case of a 67-year-old Hispanic female that presented with an asymptomatic growing mass in her right thigh. She was managed with an En bloc resection under the impression of a smooth muscle vascular sarcoma. The diagnosis was confirmed after histopathologic evaluation.Clinical discussionVascular leiomyosarcomas remain a rare and challenging diagnosis. They usually present as a slowly growing mass that is initially asymptomatic. High clinical suspicion and a comprehensive radiologic evaluation, including magnetic resonance imaging, are crucial. Histopathological evaluation is essential for diagnostic confirmation. Surgical excision remains the treatment of choice, with radiation therapy mostly considered for local disease control. Postsurgical surveillance is necessary every three months to monitor for signs of recurrence.ConclusionPhysicians should remain aware of the nonspecific presentation of leiomyosarcomas and the importance of a comprehensive diagnostic approach. Early diagnosis and adequate management are fundamental elements in the treatment of these aggressive tumors.

Malignant Psoas Syndrome

The patient in this case presented with a malignant psoas syndrome secondary to a primary psoas muscle sarcoma. A malignant psoas syndrome is characterized by the presence of lumbar plexopathy, ipsilateral hip flexion, and severe pain with attempted hip extension. The presence of severe, atraumatic joint pain with fevers and other associated systemic symptoms should raise the clinical index of suspicion for a diagnosis requiring urgent attention including infection and malignancy.

English

BACKGROUND Leiomyosarcomas (LMS) of inferior vena cava (IVC) are rare smooth muscle sarcomas with less than 300 cases described in the literature. Leiomyosarcoma of IVC is, often detected late in the course due to its indolent manifestation. This study intends to discuss the experiences and challenges in diagnosing this rare entity primarily by radiological imaging in a tertiary centre in India. METHODS This is a retrospective analysis of computed tomography (CT) and ultrasound findings in 6 cases of leiomyosarcoma of inferior vena cava who were referred for multidetector computer tomography (MDCT) scan in the Department of Radiodiagnosis of Government Medical College Calicut over the past 7 years by the treating physician. The patients were identified using a prospectively maintained database. RESULTS In this study, there were six patients diagnosed as leiomyosarcoma of IVC, age ranging from 35 and 64 years (mean 47.8 years, SD 10.7) with 4 (66.6 %) females and 2 (33.33 %) males. The mean size of the tumour at the time of diagnosis was 8.4 cm. The segment of IVC most commonly involved was middle segment in 5 patients (83.3 %). In this series, only a single case had tumour entirely confined within the lumen of inferior vena cava without extraluminal extension. Two out of six cases (16.66 %) had lung metastasis at the time of diagnosis. Two cases without metastasis or significant infiltration to adjacent organs were amenable to resection. CONCLUSIONS Leiomyosarcoma of IVC is a rare tumour, often detected late in the course due to its indolent manifestation. High index of suspicion may help in the early diagnosis of so that early treatment can begin and improve the clinical outcome. KEYWORDS Leiomyosarcoma, Inferior Vena Cava, Mesenchymal Neoplasms

Correlation between oncological family history and clinical outcome in a large monocentric cohort of pediatric patients with rhabdomyosarcoma.

Rhabdomyosarcoma (RMS), an aggressive soft tissue sarcoma of the skeletal muscle generally affecting children and adolescents, shows extensive heterogeneity in histology, site and age of onset, clinical course, and prognosis. Tumorigenesis of RMS is multifactorial and genetic predisposition together with the family history of cancer may provide critical information to enhance the current knowledge and foster genetic counseling and testing. In our study, we evaluated the possible correlation of oncological family history with clinical outcomes in a cohort of RMS 512 patients and treated at the Pediatric Oncology Unit of our Institute. Family history was retrospectively collected from the specific ad hoc form available in medical records and filled in through an interview with the patients' parents at the time of RMS diagnosis. While our series did not show a specific association between oncological family history and clinical variables, we observed an association with survival probabilities: among patients with a history of cancer-affected first-degree relatives at the time of the diagnosis, all children with alveolar RMS (ARMS) died of disease. Our study not only reports an interesting and not previously described association between a poor clinical outcome and ARMS in patients with young cancer-affected relatives, but also stimulates the discussion on oncological family history in RMS, to improve the clinical management of these young patients and their families.

Cutaneous leiomyosarcoma /
 atypical smooth muscle sarcoma

Relevance: Cutaneous leiomyosarcoma is a rare primary
 dermal neoplasm, accounting for up to 2-3% of all superficial
 sarcomas. It can occur at any age, most likely between the ages
 of 50 and 70 years. This tumor has a high recurrence potential
 in case of insufficiently deep excision. Recurrent tumors are
 more aggressive and characterized by subsequent metastasis.
 The purpose of the study was to demonstrate the results
 of the histopathological examination of a cutaneous leiomyosarcoma / atypical smooth muscle tumor.
 Results: Cutaneous leiomyosarcoma was represented by
 spindle-shaped cells with high cellularity located in bundles
 and growing expansively, surrounded by a capsule. The nuclei
 of the cells were elongated, hyperchromic. Cells with atypical
 abnormal nuclei were present in smaller quantities. The mitoses, including atypical, were numerous. IHC staining for SMA,
 Desmin, H-Caldesmon – diffusely positive on tumor cells. The
 reaction for S100, Myogenin – negative.
 Conclusion: A cutaneous leiomyosarcoma can be finally
 diagnosed only after a pathomorphological examination of
 the specimen and differential diagnostics using additional research methods.

Cutaneous leiomyosarcoma/
 atypical smooth muscle sarcoma

Relevance: Cutaneous leiomyosarcoma is a rare primary dermal neoplasm, accounting for up to 2-3% of all superficial
 sarcomas. It can occur at any age, most likely between the ages of 50 and 70 years. This tumor has a high recurrence potential
 in case of insufficiently deep excision. Recurrent tumors are more aggressive and characterized by subsequent metastasis.
 The purpose of the study was to demonstrate the results of the histopathological examination of a cutaneous
 leiomyosarcoma / atypical smooth muscle tumor.
 Results: Cutaneous leiomyosarcoma was represented by spindle-shaped cells with high cellularity located in bundles
 and growing expansively, surrounded by a capsule. The nuclei of the cells were elongated, hyperchromic. Cells with atypical
 abnormal nuclei were present in smaller quantities. The mitoses, including atypical, were numerous. IHC staining for SMA,
 Desmin, H-Caldesmon – diffusely positive on tumor cells. The reaction for S100, Myogenin – negative.
 Conclusion: A cutaneous leiomyosarcoma can be finally diagnosed only after a pathomorphological examination of the
 specimen and differential diagnostics using additional research methods

Risk of hepatitis B virus reactivation in patients with solid tumors receiving systemic chemotherapy

Abstract Background Hepatitis B virus (HBV) reactivation is known as a risk of chemotherapy in patients with hematopoietic tumors at a rate of 14 to 72%. Screening tests for HBV (HBsAg, HBsAb, HBcAb) are recommended for chemotherapy in patients with solid tumors, however there are a few reports of risk of HBV reactivation and management other than hematopoietic tumors. Patients and Methods We analyzed 18 HBV-DNA positive patients who received systemic chemotherapy for malignancies between October 2017 and February 2019. Results The 18 patients included 2 with hematopoietic tumors and 16 with solid tumors. Among them, 4 showed negative for HBsAg before chemotherapy (1 each with breast cancer, neuroendocrine carcinoma, smooth muscle sarcoma, and colon cancer), and other 12 were HBsAg-positive. One of the HBsAg-negative patients developed active hepatitis and was treated with nucleoside. The other 3 presented positive for HBV-DNA in the absence of active hepatitis through the clinical course. 11 of the 12 HBsAg-positive patients showed HBV-DNA positive, and received nucleoside analog without active hepatitis. Most of the attending physicians had not perceived HBV-positivity in the patients before notification by the hepatologists. Conclusion The treatment of hematopoietic malignancies as well as solid tumors may develop HBV reactivation. HBV screening is recommended according to guidelines before chemotherapy. The intervention of hepatologists in a hospital is necessary for all patients receiving chemotherapy.

2617 Duodenal Leiomyosarcoma: A Rare Cause of Gastric Outlet Obstruction

INTRODUCTION: Intestinal leiomyosarcoma (LMS) is a rare cancer comprising 0.2% of all malignant tumors and involves the ileum in nearly half of cases. The remainder occur in the proximal duodenum and jejunum primarily, or metastatically from non-intestinal sites such as the uterus. We report this case of primary duodenal LMS complicated by gastric outlet obstruction. CASE DESCRIPTION/METHODS: A 57 year old woman presented with a two month history of worsening epigastric and right upper quadrant pain without nausea, vomiting, weight loss, or altered bowel habits. On physical exam she had marked epigastric tenderness. Abdominal contrast CT demonstrated multiple hypodense liver lesions measuring up to 2cm and a mildly dilated and thickened descending segment of the duodenum. Laboratory evaluation including tumor markers was normal. Without a clear primary malignancy source, the patient underwent percutaneous liver biopsy. Histopathology revealed high grade smooth muscle sarcoma, which stained positively for desmin, SMA, CD 57, and CD 34. Chemotherapy with gemcitabine and docetaxel was initiated per oncology. Within weeks, the patient developed worsening abdominal pain, nausea, and vomiting. CT imaging showed a mass projecting over the descending duodenum causing gastric outlet obstruction. After nasogastric decompression, the patient underwent an EGD. A friable, circumferential mass was seen emanating from distal duodenal bulb extending proximally to the second portion. A duodenal self expanding metal stent was inserted from just proximal to the ampulla to the distal antrum, effectively bridging the mass. Biopsy of the mass was consistent with high grade sarcoma, identical to the liver biopsy. Upper GI contrast series confirmed stent patency; patient tolerated an appropriately advanced diet, and was discharged home to continue outpatient chemotherapy. DISCUSSION: Based on our literature review, there have been no documented cases of gastric outlet obstruction secondary to duodenal LMS. Such tumors often present with abdominal pain and bleeding due to their highly vascular nature. In general, small intestinal malignancies are rare and often difficult to diagnose due to non-specific symptomatic progression resulting in delayed evaluation. Disease is often advanced to lymphatic spread or metastasis at diagnosis as was the case in our patient. A broad differential diagnosis should be considered in patients with unclear primary malignancies presenting with obstructive symptoms.

Multiple Epstein-Barr Virus–associated Smooth Muscle Sarcomas of the Gut in a Child Treated for Acute Lymphoblastic Leukemia

A 7-year-old boy with a history of low-risk acute lymphoblastic leukemia developed multiple intussusceptions shortly after the end of maintenance therapy. Explorative laparotomy showed >10 polyps in the small intestine. Histologic examination revealed intestinal smooth muscle sarcomas associated with Epstein-Barr virus. The patient recovered well after partial cuneiform resection of the largest polyps and treatment with sirolimus. This case report indicates that these tumors may arise even after moderate transient immunosuppression and that association with acute lymphoblastic leukemia is possible although rarely described. We discuss the potential benefit of the mTor/Akt signal inhibitors as treatment for these tumors.

Urinary smooth muscle sarcoma in a labrador retriever

Urinary smooth muscle sarcoma in a labrador retriever

Management of the "Other" retroperitoneal sarcomas.

The focus of this review is on the management of the less common sarcomas occurring in the retroperitoneal space, including solitary fibrous tumor (SFT), malignant peripheral nerve sheath tumor (MPNST), perivascular epithelioid cell tumor (PEComa), and undifferentiated pleomorphic sarcoma (UPS) of the psoas muscle. As for other retroperitoneal sarcomas, surgical resection is the mainstay of curative therapy, and multidisciplinary preoperative assessment, including percutaneous needle biopsy for histologic confirmation, is the basis for personalized management, as the surgical management, and the integration of systemic therapy and radiation therapy is unique to each histologic subtype.

Histopathological Spectrum of Soft-Tissue Tumors with Immunohistochemistry Correlation and FNCLCC grading: A North Indian Experience.

Introduction:Soft tissue tumors (STT) are mesenchymal neoplasms with a diverse spectrum and overlapping clinical, radiological and histological features. Histopathology and immunohistochemistry (IHC) are essential to make a diagnosis. Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) Sarcoma Group grading system based on tumour differentiation, mitotic rate and necrosis helps in predicting the tumour progression and treatment response.Aims:The goal of this study was to analyze the incidence, histological spectrum and IHC features of STTs and to grade sarcomas according to FNCLCC grading system.Material and Methods:This is a four year study conducted in the Department of Pathology of a tertiary care centre from July 2009 to June 2013. All histopathologically diagnosed STTs were evaluated for gross and microscopic appearance. IHC was done wherever needed and clinical correlation was attempted. Sarcomas were graded according to FNCLCC grading system.Results:Of the total 270 cases studied, benign, intermediate and malignant STTs were 67.0%, 7.0% and 25.9% respectively. Adipocytic, vascular and peripheral nerve sheath tumors (PNST) formed the bulk of overall STTs (34.1%, 18.5% and 11.1% respectively). Sarcomas not otherwise specified were found to be the most common soft-tissue sarcomas followed by smooth muscle sarcomas and tumors with uncertain differentiation (11.5%, 4.1%, and 3.3%, respectively). Benign STTs were seen two decades earlier and were superficial in location as compared to sarcomas. On FNCLCC grading, grade 3 soft tissue sarcomas were slightly higher in number than grade 2 (27 vs 24). On IHC a definitive diagnosis was reached in 33 malignant, all intermediate and nine benign cases.Conclusion:The incidence of intermediate and malignant STTs is increasing due to early detection and better diagnosis by ancillary techniques like IHC. FNCLCC grading helps to prognosticate the malignant STTs thus guiding further plan of action while in some tumors like MPNST and Angiosarcoma it has no prognostic significance.

Radiation-induced undifferentiated pleomorphic sarcoma after radiation therapy for a desmoid tumour

Radiation-induced sarcoma is a long-term complication of radiation therapy. The most common secondary neoplasia is the undifferentiated pleomorphic sarcoma, which is usually described in the deep soft tissue of the trunk or extremities. Radiation-induced sarcomas have a poor prognosis. An early diagnosis and management are needed to improve the survival rate of such patients. We presently report a case of a radiation-induced undifferentiated pleomorphic sarcoma of the left gluteus maximus muscle, which developed 25years after an initial diagnosis of aggressive fibromatosis and 21years after a tumour recurrence. This case study illustrates the risk of developing a sarcoma in a radiation field and the need for long-term follow-up after radiation therapy. Unnecessary radiation therapy, in particular in the case of benign conditions in young patients, should be avoided.

Exérèse large d’un sarcome de l’épaule et reconstruction en un temps par double lambeau de grand dorsal et de grand dentelé pédiculé. Discussion à propos d’un cas

The soft tissue sarcomas (STM) are tumors developed at the expense of connective tissue. They are rare and have severe prognosis. The principles of management are recalled through an extended case of shoulder sarcoma. A 48-year-old patient has a sarcoma of the right pectoralis major muscle confirmed by biopsy. After multidisciplinary meeting, a wide surgical excision exposing the subclavian vessels and brachial plexus is performed with double cover flap pedicled latissimus dorsi and serratus and thin skin graft. Healing process is acquired at 3months. Adjuvant chemotherapy is established (adriamycin, ifosfamide) along with radiotherapy (54Gy). Sarcomas treatment has to be realized after considering multidisciplinary meeting (RCP) in dedicated structures. Surgery is the main treatment, it should ideally be R0, that is to say, integral with healthy tissue margin around the tumor (or healthy anatomical barrier). Optimal surgery performs a resection "without seen tumor". The diagnosis has to be made with a biopsy before the surgical treatment. Healing is quickly obtained due to adjuvant treatments.

Abstract 5153: Myogenic regulatory factors and their role in embryonal rhabdomyosarcoma

Abstract Rhabdomyosarcoma (RMS) is a pediatric sarcoma of muscle. RAS pathway activation is the dominant oncogenic driver event in fusion negative RMS, which includes the Embryonal RMS (ERMS). We have previously shown in a transgenic zebrafish model of kRASG12D induced ERMS that tumor-propagating potential is confined to molecularly defined cells that express Myf5, m-Cadherin, c-Met and additional satellite cell markers. MYF5 and MYOD1 are bHLH myogenic regulatory factors (MRFs) that orchestrate skeletal muscle differentiation during development and regeneration. Both are sufficient to reprogram human mesenchymal cells into a myogenic fate. Importantly, these same factors are highly expressed a subset of mouse and human ERMS. Given that Myf5 is highly and specifically expressed in the TPC compartment in our ERMS model, we hypothesized that Myf5 and its transcriptional targets may regulate self-renewal and growth of TPCs. To address this question, we utilized transgenic zebrafish and expressed Myf5 in differentiated ERMS cells that lack proliferative capacity and can not make tumors when transplanted into recipient fish. Induced expression of Myf5 was sufficient to confer tumor-propagating ability to differentiated populations of ERMS cells. These “Induced TPCs” proliferate and generate aggressive tumors that re-express satellite cell markers and yet retain expression of mature muscle markers. Next, we assessed if Myf5 is required for ERMS initiation in the zebrafish model. Remarkably, kRASSG12D-induced ERMS could be generated in Myf5 loss-of-function zebrafish. Moreover, Myf5-deficient ERMS could regrow following transplantation into rag2E450fs immune-compromised zebrafish; however, these tumors are histologically and molecularly distinct when compared with ERMS arising in wild-type fish. Given the redundancy of function between Myf5 and MyoD in muscle and their differential expression in satellite cells and muscle progenitors, our current hypothesis is that Myf5-deficient zebrafish ERMS likely recapitulate a molecularly-distinct class of human ERMS. This idea is consistent with the fact that MYF5 is expressed in only 50% of primary human ERMS and a small fraction of human cell lines. Importantly, knock down experiments in human ERMS cell lines confirm independent roles of either MYF5 or MYOD1 in maintenance of ERMS cell viability in vitro. Collectively, our results support a previously unappreciated role for bHLH MRFs in ERMS cell survival and intra-tumor functional heterogeneity and suggest that myogenic factor expression may define unique subtypes of ERMS. Citation Format: Ines M. Tenente, Myron Ignatius, Eleanor Chen, Madeline Hayes, David M. Langenau. Myogenic regulatory factors and their role in embryonal rhabdomyosarcoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5153. doi:10.1158/1538-7445.AM2015-5153

Comparison of ADC values in different malignancies of the skeletal musculature: a multicentric analysis.

Diffusion-weighted imaging (DWI) provides essential information regarding tumor composition, such as cellularity and/or perfusion. DWI is helpful in distinguishing between malignant and benign lesions. Malignant intramuscular/soft tissue lesions consist of a wide spectrum of tumors that have different cell counts and matrix. It is presumed that these different tumors have different DWI findings and have different apparent diffusion coefficient (ADC) values. The aim of this study was to analyze DWI findings of different intramuscular malignancies in a multicentric study by using a standardized DWI protocol, and to compare the ADC values acquired. The data banks of four radiology departments were screened retrospectively for malignant intramuscular tumors. Only lesions that were investigated by MRI (with a 1.5-T scanner) using DWI (multishot EPI sequence with b values of 0 and 1,000 s/mm(2)) were included in the study. Overall, 51 patients (28 women, 23 men; mean age 58.8 ± 16.1 years) with 57 different malignant intramuscular lesions were collected. In every case apparent diffusion constant (ADC) maps were calculated. In 14 patients muscle lymphoma, 11 patients intramuscular metastases from different primary tumors, and in 26 cases several muscle sarcomas were identified. The mean ADC value of the estimated lesions was 1.24 ± 0.53 × 10(-3) mm(2)s(-1), median value, 1.11 × 10(-3) mm(2)s(-1), range, 0.54-2.9 × 10(-3) mm(2)s(-1). The mean ADC value in muscle metastases was 1.28 ± 0.24 × 10(-3) mm(2)s(-1), in muscle lymphoma 0.76 ± 0.14 × 10(-3) mm(2)s(-1), and in muscle sarcomas 1.82 ± 0.63 × 10(-3) mm(2)s(-1). Muscle lymphoma showed statistically significant lower ADC values in comparison to muscle metastases (p = 0.01) and muscle sarcoma (p = 0.001). There was no significant differences between ADC values in muscle metastases and sarcomas (p = 0.48). ADC values in muscle lymphoma were homogeneous with less inter-patient variability and were within a relatively close range. Muscle sarcomas had a broad range of ADC values. Intramuscular malignant lesions had different ADC values on DWI. 22.8% of the tumors analyzed had low ADC values, 26.3% moderate, and 50.9% high ADC values. Muscle lymphoma had statistically significantly lower ADC values in comparison to muscle metastases and sarcomas. Muscle sarcomas presented with a broad range of ADC values.

Quantitative magnetic resonance imaging of microvascular changes in KHT sarcoma

Micromorphological changes in skeletal muscle vascular remodeling due to denervation, aging or tumour growth have been investigated recently. Naturally, quantitative imaging of the capillary bed and the determination of microstructural parameters in healthy and pathological tissue might prove beneficial for potential therapeutic interventions. Susceptibility differences of capillaries and surrounding tissue are due to paramagnetic deoxyhaemoglobin and can be used to provide a means of quantifying microstructural parameters through MRI transverse relaxation time measurements. Within a local weak field approximation and based on simple geometrical assumptions, a model is introduced that analytically derives a dependence of blood transverse relaxation rate for Carr-Purcell-Meiboom-Gill sequences on inter-pulse delay time, strength of the magnetic field, local susceptibility difference and spin diffusion constant, capillary radius and local blood volume fraction. The model is tested for healthy skeletal muscle tissue in mouse leg muscle and KHT sarcoma based on experimental ex-vivo experiments. Due to blood loss and increased vessel wall permeability after excision, a capillary shrinkage to about 1/10 of the typical in-vivo capillary diameter of 1.5 µm is assumed, and, in a magnetic field of 0.6 T, the corresponding local diffusion constant in healthy tissue is found to be 2.2 µm2/ms, and for KHT sarcoma 2.6 µm2/ms. Therefore, the quantitative model might be used to differentiate between healthy and pathological tissue diffusion properties or, by assuming local diffusive properties, to determine differences in local microvasculature.