Magnetic resonance imaging in teenagers and young adults with limited haemophilic arthropathy: baseline results from a prospective study.

The clinical relevance of subtle changes on magnetic resonance imaging (MRI) for evaluating haemophilia treatment is unknown. To determine the relationship of findings on MRI with joint function and bleeding in joints with apparently very mild arthropathy, a prospective study was performed. Knees and ankles of 26 patients, 13-26 years, were scanned. Two blinded radiologists scored the MRI (IPSG consensus score) and the radiography [Pettersson score (PS)]. Clinical function (HJHS) was scored by one physiotherapist. Life-time number of bleeds was collected from patient files. Of 104 joints scanned, three were excluded because of previous arthrodesis or trauma. Remaining 101 MRI scores correlated weakly with clinical function (r = 0.27, P = 0.01) and less with lifetime number of bleeds (r = 0.16, P = 0.14). MRI scores were 0 in 58 joints, including 27 with major bleeds. In three joints of patients playing intensive sports MRI showed minor changes (MRI score = 1) in the absence of bleeds. Agreement was reasonable between PS and MRI score (r = 0.41, P < 0.01). In 30% of joints, MRI detected abnormalities in soft-tissue and cartilage, while PS was 0 points. No evidence of occult haemorrhages was found. Instead, we found no abnormalities on MRI in 43 joints with a history of repeated joint bleeding. Haemosiderin seemed associated with the time between assessment and last bleed; joints that had suffered a bleed long before MRI had hardly haemosiderin, while those with a recent bleed showed haemosiderin, suggesting joint damage may be reversible. Abnormalities detected by MRI, but not by PS were minor and their clinical implications are not yet clear.

Proceedings of the European Society of Musculoskeletal Radiology (ESSR) training module, Antwerp, 20-21.01.05. Part two: bone tumors. Benign bone lesions: characteristic imaging features.

Benign bone lesions are a fairly common finding in radiology practice. Often, the combination of patient's age and plain radiographic findings are sufficient for diagnosis and obviates the need for further imaging. Generally the following parameters should be assessed in the evaluation of a bone lesion: clinical features, age of the patient, location, size, pattern of bone destruction, cortical involvement, zone of transition, sclerotic margination and matrix calcification. Cross sectional imaging, such as CT or MRI complements radiography, especially in complex anatomical sites. This article reviews the spectrum of clinical and imaging appearances of the most common benign bone tumors.

Imaging features of peripheral neurogenic tumors.

Peripheral nerve sheath tumors (PNST) include schwannoma, neurofibroma and malignant peripheral sheath tumors. All neurogenic tumors share the same imaging characteristics, including fusiform shape, low attenuation on CT, fascicular sign, split fat sign and associated muscle atrophy. The aim of this article is to give a comprehensive overview of peripheral nerve tumors and to discuss the imaging characteristics that distinguish these masses.

Prevalence, extension and characteristics of fluid-fluid levels in bone and soft tissue tumors.

The purpose of this study was to determine the prevalence, extension and signal characteristics of fluid-fluid levels in a large series of 700 bone and 700 soft tissue tumors. Out of a multi-institutional database, MRI of 700 consecutive patients with a bone tumor and MRI of 700 consecutive patients with a soft tissue neoplasm were retrospectively reviewed for the presence of fluid-fluid levels. Extension (single, multiple and proportion of the lesion occupied by fluid-fluid levels) and signal characteristics on magnetic resonance imaging of fluid-fluid levels were determined. In all patients, pathologic correlation was available. Of 700 patients with a bone tumor, 19 (10 male and 9 female; mean age, 29 years) presented with a fluid-fluid level (prevalence 2.7%). Multiple fluid-fluid levels occupying at least one half of the total volume of the lesion were found in the majority of patients. Diagnoses included aneurysmal bone cyst (ten cases), fibrous dysplasia (two cases), osteoblastoma (one case), simple bone cyst (one case), telangiectatic osteosarcoma (one case), "brown tumor" (one case), chondroblastoma (one case) and giant cell tumor (two cases). Of 700 patients with a soft tissue tumor, 20 (9 males and 11 females; mean age, 34 years) presented with a fluid-fluid level (prevalence 2.9%). Multiple fluid-fluid levels occupying at least one half of the total volume of the lesion were found in the majority of patients. Diagnoses included cavernous hemangioma (12 cases), synovial sarcoma (3 cases), angiosarcoma (1 case), aneurysmal bone cyst of soft tissue (1 case), myxofibrosarcoma (1 case) and high-grade sarcoma "not otherwise specified" (2 cases). In our series, the largest reported in the literature to the best of our knowledge, the presence of fluid-fluid levels is a rare finding with a prevalence of 2.7 and 2.9% in bone and soft tissue tumors, respectively. Fluid-fluid levels remain a non-specific finding and can occur in a wide range of bone and soft tissue tumors, both benign and malignant. Therefore, they cannot be considered diagnostic of any particular type of tumor, and the diagnosis should be made on the basis of other radiological and clinical findings.

Soft tissue aneurysmal bone cyst.

A soft tissue aneurysmal bone cyst located in the right gluteus medius of a 21-year-old man is reported. On conventional radiography, the lesion demonstrated a spherically trabeculated mass with a calcific rim. On CT scan, it showed a well-organized peripheral calcification resembling a myositis ossificans. On MRI, it presented as a multilocular, cystic lesion with fluid-fluid levels. The lesion had no solid components except for intralesional septa. Although findings on imaging and histology were identical to those described in classical aneurysmal bone cyst, diagnosis was delayed because of lack of knowledge of this entity and its resemblance to the more familiar post-traumatic heterotopic ossification (myositis ossificans).

Spinal tumors.

Spinal tumors are uncommon lesions but may cause significant morbidity in terms of limb dysfunction. In establishing the differential diagnosis for a spinal lesion, location is the most important feature, but the clinical presentation and the patient's age and gender are also important. Magnetic resonance (MR) imaging plays a central role in the imaging of spinal tumors, easily allowing tumors to be classified as extradural, intradural-extramedullary or intramedullary, which is very useful in tumor characterization. In the evaluation of lesions of the osseous spine both computed tomography (CT) and MR are important. We describe the most common spinal tumors in detail. In general, extradural lesions are the most common with metastasis being the most frequent. Intradural tumors are rare, and the majority is extramedullary, with meningiomas and nerve sheath tumors being the most frequent. Intramedullary tumors are uncommon spinal tumors. Astrocytomas and ependymomas comprise the majority of the intramedullary tumors. The most important tumors are documented with appropriate high quality CT or MR images and the characteristics of these tumors are also summarized in a comprehensive table. Finally we illustrate the use of the new World Health Organization (WHO) classification of neoplasms affecting the central nervous system.

Pictorial essay. Myositis ossificans circumscripta.

Myositis ossificans circumscripta (MOC) is a localized, non-neoplastic, heterotopic ossification within the muscle. Despite advances in medical imaging, it remains difficult to distinguish it from other disorders. As a consequence, a biopsy is frequently performed. We illustrate some common findings and non-specific imaging features of MOC with respect to radiography, computed tomography, bone scintigraphy, ultrasonography, and magnetic resonance imaging. The differentiation among MOC and its mimics is also presented in order to help the radiologists to make an appropriate diagnostic decision.

Additional value of magnetic resonance with spin echo T1-weighted imaging with fat suppression in characterization of soft tissue tumors.

OBJECTIVE: The aim of the study was to describe the signal intensity (SI) behavior of soft tissue tumors (STT) on spin echo (SE) T1 weighted images (WI) with fat suppression (FS) and to assess its additional value in tissue characterization. METHODS: MRI signal characteristics of 53 histological proven STT were discussed. Signal intensity behavior of STT could be classified in 4 types, representing specific tissues or tissue components. Type 1 was defined as low SI on both SE T1-WI and SE T1-WI with FS. Type 2 was defined as high SI on both sequences. Type 3 consisted of high SI on T1-WI and low SI on T1-WI with FS. Type 4 was defined as SI comparable with SI of normal muscle on T1-WI and SI higher than normal muscle on T1-WI with FS. The additional information concerning contrast enhancement is described. RESULTS: Type 1 SI behavior was noted in fibrous lesions, in hemosiderotic components, cysts, and myxoma. Type 2 was noted in lesions containing methemoglobin or melanin. Type 3 was specific for fatty tissue. Type 4 was noted in highly cellular parts and in lesions of vascular origin. The use of SE T1-WI with FS improved lesion conspicuity on T1-WI. CONCLUSIONS: E T1-WI with FS has additional value in the characterization of fibrous and hemosiderotic parts from cellular parts of lesions. It gives more confidence in characterization of neurogenic tumors and hemangioma's. Presence of methemoglobin and melanin are clearly discriminated from fatty tissue. Tumor conspicuity and inhomogeneity evaluation is improved. The use of SE T1-WI FS not only improves tumor conspicuity, but as tumor homogeneity and SI are important parameters in staging and characterization of STT, the use of SE T1-WI with FS will certainly be helpful. This may obviate the need for gadolinium administration.

Nodular fasciitis: correlation of MRI findings and histopathology.

OBJECTIVE: To compare the histopathology of nodular fasciitis (NF) with the magnetic resonance imaging (MRI) findings in order to evaluate the basis of the MR signal characteristics. DESIGN AND PATIENTS: Ten patients with NF, nine females and 1 male, with an age ranging from 13 to 58 years (mean 26.8 years) were studied. MRI findings, available in all 10 patients, were compared with the histopathology in nine patients, and an area-to-area comparative study of the whole specimen section histopathology and MRI was performed in two patients. RESULTS: On the basis of an excisional biopsy or resection specimen, the nine lesions were classified into myxoid ( n=4), cellular ( n=3) and fibrous ( n=2) subtypes. Four myxoid lesions with a subcutaneous location showed a homogeneous SI comparable with muscle on T1-weighted images, high SI on T2-weighted images, and had homogeneous enhancement. One cellular lesion presented with homogeneous, slightly higher SI than muscle on T1-weighted images and inhomogeneous, high SI on T2-weighted images. Alcian blue stain of the whole specimen section revealed the lesion had two parts corresponding to different enhancement patterns on MRI. The blue-stained myxoid part showed markedly diffuse enhancement, while the non-stained cystic space had only peripheral enhancement. Two other cellular lesions had the same appearance on both T1- and T2-weighted images and showed inhomogeneous, diffuse enhancement. One fibrous subtype lesion presented with inhomogeneous, overall slightly higher SI than muscle on T1-weighted images, lower SI at the periphery and high SI in the center on STIR images and only peripheral enhancement. Microscopy and CD-31 staining of the lesion showed more extracellular matrix, with poor vascularity in the center and more collagenous matrix with higher vascularity at the periphery. CONCLUSION: Although similar findings were found in some lesions, the large histologic variability of NF hampers the definition of a prototype of NF on MRI. However, the MRI appearance of the myxoid subtype is rather characteristic. Histologic findings reflect the different SI characteristics and enhancement pattern on MRI.