Laura W. Bancroft

Malignant fatty tumors: classification, clinical course, imaging appearance and treatment

Liposarcoma is a relatively common soft tissue malignancy with a wide spectrum of clinical presentations and imaging appearances. Several subtypes are described, ranging from lesions nearly entirely composed of mature adipose tissue, to tumors with very sparse adipose elements. The imaging appearance of these fatty masses is frequently sufficiently characteristic to allow a specific diagnosis, while in other cases, although a specific diagnosis is not achievable, a meaningful limited differential diagnosis can be established. The purpose of this paper is to review the spectrum of malignant fatty tumors, highlighting the current classification system, clinical presentation and behavior, treatment and spectrum of imaging appearances. The imaging review will emphasize CT scanning and MR imaging, and will stress differentiating radiologic features.

Erdheim-Chester disease: radiographic findings in five patients

Abstractu2002We present the case histories of five patients with Erdheim-Chester disease, a rare lipoidosis that has several typical radiographic features. In all the patients, the diaphyses and metaphyses of the extremities demonstrated a symmetric pattern of diffuse or patchy increased density, a coarsened trabecular pattern, medullary sclerosis, and cortical thickening. The epiphyses were spared in four patients and partially involved in one. The axial skeleton was involved in one patient. Radiotracer 99mTc accumulated in areas of radiographic abnormalities in all patients. In one patient, MRI demonstrated an abnormal signal, corresponding to radiographic abnormalities. The signal was hypointense to muscle on T1-weighted sequences and heterogeneously hyperintense and hypointense to normal bone marrow on T2-weighted sequences. Xanthogranulomatous lesions infiltrated the retroperitoneum in one patient, the testes in one patient, the eyelids in one patient, and the orbits in two patients.

Benign and Malignant Soft-Tissue Tumors: Posttreatment MR Imaging

Soft-tissue sarcoma requires aggressive treatment, often with a combination of radiation therapy, chemotherapy, and surgical resection. Even after multimodality treatment, local recurrence is common, and regular follow-up imaging at short intervals is required. Interpretation of posttreatment magnetic resonance (MR) images may be complicated by changes in the surgical bed or treatment field. The challenge of distinguishing posttreatment change from recurrent tumor may be minimized by using an organized, systematic approach to imaging, with emphasis on the patients clinical and surgical history and a review of pretreatment images. Common changes that result from radiation therapy include soft-tissue trabeculation, increased fatty marrow, and focal marrow abnormalities. Rarely, radiation-induced malignancies may develop within the treatment field. Chemotherapy also influences posttreatment imaging appearance. Occasionally, it causes a substantial increase in tumor size that is a result of chemotherapy-induced hemorrhage. Although myocutaneous flaps used in reconstructive surgery may mimic a mass, they demonstrate time-dependent changes in size, signal intensity, and enhancement on MR images. Recurrent tumor is characterized by the presence of a discrete nodule or mass with signal characteristics that typically mirror those of the original tumor. MR imaging sequences such as unenhanced T1-weighted fat-suppressed and gradient-echo sequences may help differentiate posttreatment hemorrhage from local tumor recurrence. A consistent imaging approach combined with a detailed knowledge of the patients history, familiarity with pretreatment images, and an understanding of the various posttreatment changes enables optimal monitoring of the treatment bed and maximizes accuracy in the detection of recurrence.

Magnetic resonance imaging of the sacral plexus and piriformis muscles

ObjectiveThe objective was to evaluate the piriformis muscles and their relationship to the sacral nerve roots on T1-weighted MRI in patients with no history or clinical suspicion of piriformis syndrome.Patients and methodsAxial oblique and sagittal T1-weighted images of the sacrum were obtained in 100 sequential patients (200 pairs of sacral roots) undergoing routine MRI examinations. The relationship of the sacral nerve roots to the piriformis muscles and piriformis muscle size were evaluated, as were clinical symptoms via a questionnaire.ResultsThe S1 nerve roots were located above the piriformis muscle in 99.5% of cases (n=199). The S2 nerve roots were located above the piriformis muscle in 25% of cases (n=50), and traversed the muscle in 75% (n=150). The S3 nerve roots were located above the piriformis muscle in 0.5% of cases (n=1), below the muscle in 2.5% (n=5), and traversed the muscle in 97% (n=194). The S4 nerve roots were located below the muscle in 95% (n=190). The piriformis muscles ranged in size from 0.8–3.2xa0cm, with an average size of 1.9xa0cm. Nineteen percent of patients had greater than 3xa0mm of asymmetry in the size of the piriformis muscle, with a maximum asymmetry of 8xa0mm noted.ConclusionThe S1 nerve roots course above the piriformis muscle in more than 99% of patients. The S2 roots traverse the piriformis muscle in 75% of patients. The S3 nerve roots traverse the piriformis muscle in 97% of patients. Piriformis muscle size asymmetry is common, with muscle asymmetry of up to 8xa0mm identified.

Imaging appearance of diffuse neurofibroma.

OBJECTIVEnThe purposes of this study were to describe the imaging appearance of diffuse neurofibroma in 10 patients and to summarize demographic data on a large group of patients.nnnMATERIALS AND METHODSnRetrospective review of the pathology and radiology teaching databases at two institutions yielded the cases of 339 patients with a pathologic diagnosis of diffuse neurofibroma. Diagnostic-quality images were available for 10 patients. Images from MRI (n = 8), CT (n = 5), and sonographic (n = 1) examinations were evaluated for lesion location, size, depth of involvement, growth pattern, and intrinsic signal intensity, attenuation, or echogenicity. Demographic information, associated lesions, and tumor location were recorded for all patients.nnnRESULTSnAmong 10 patients with images, eight of whom had neurofibromatosis, diffuse neurofibroma involved the skin and subcutaneous tissues (n = 9) and frequently extended to the fascia over muscle (n = 6). Plaquelike (n = 5) and infiltrative (n = 3) growth patterns were most common. One lesion had a mixed growth pattern. Prominent internal vascularity was common (n = 5). MRI signal intensity and CT attenuation were typically nonspecific. Enhancement was intense in all five patients with contrast-enhanced MR examinations. Including patients with and those without images, 349 diffuse neurofibromas were present in 339 patients. The mean patient age was 35.1 years. Lesions involved the extremities (n = 120), trunk (n = 122), head and neck (n = 98), and deep structures (n = 9).nnnCONCLUSIONnDiffuse neurofibroma frequently grows as a plaquelike or infiltrative lesion involving the skin and subcutaneous tissues. Prominent internal vascularity is common. There is a much wider soft-tissue and age distribution and association with neurofibromatosis than previously reported.

Postoperative Evaluation of the Total Ankle Arthroplasty

OBJECTIVEnThe purpose of this article is to review the basic design features of second-generation total ankle arthroplasty components and to illustrate the normal and abnormal postoperative imaging features associated with such devices. The usefulness of CT in postoperative evaluation will be highlighted.nnnCONCLUSIONnPostoperative evaluation of the total ankle arthroplasty necessitates a familiarity with the various designs currently in use. Radiography serves as an integral component in the postoperative evaluation of such devices, with CT offering further characterization of radiographic abnormalities.

Cysts, geodes, and erosions

Subchondral cystic lesions are common features that are associated with many arthropathies and synovial-based processes. Although not comprehensive in scope, this article correlated the pathophysiology and imaging features of several of these disorders to better understand the associated subchondral lucencies. The imaging features of these subchondral cystic lesions were described in each process, and, in some cases, demonstrated overlapping features. By becoming familiar with the disease processes and recognizing the imaging appearances and associated clinical findings, the radiologist will be better able to differentiate these benign entities from more aggressive processes, such as tumor. Subchondral cystic lesions are common features that are associated with many arthropathies and synovial-based processes. Although not comprehensive in scope, this article correlated the pathophysiology and imaging features of several of these disorders to better understand the associated subchondral lucencies. The imaging features of these subchondral cystic lesions were described in each process, and, in some cases, demonstrated overlapping features. By becoming familiar with the disease processes and recognizing the imaging appearances and associated clinical findings, the radiologist will be better able to differentiate these benign entities from more aggressive processes, such as tumor.

Imaging of Soft Tissue Lesions of the Foot and Ankle

Differential diagnosis of soft tissue lesions of the foot can be narrowed with imaging. The cystic nature of ganglia, synovial cysts, and bursitis can be confirmed with MR imaging or sonography. Location and signal characteristics of noncystic lesions can suggest Mortons neuroma, giant cell tumor of tendon sheath, and plantar fibromatosis. Synovial-based lesions of the foot and ankle can be differentiated based on presence or absence of mineralization, lesion density, signal intensity, and enhancement pattern. Knowledge of the incidence of specific neoplasms of the foot and ankle based on patient age aids in providing a limited differential diagnosis.

Primary bone tumors of the lower extremities

The key to adequate and accurate evaluation, diagnosis, and treatment of bone tumors is an organized and integrated approach involving the surgeon, radiologist, and pathologist. The radiologist plays not only a valuable role in the diagnosis and preoperative staging of bone tumors but may also play a role in biopsy and treatment. Despite the wide variety of imaging modalities available today, radiographs remain the mainstay in the evaluation of osseous neoplasms. Advanced imaging is. however. very useful for staging purposes and for characterization of the internal characteristics of tumors and may aid significantly in limiting the differential diagnosis. Although a detailed discussion of all ofthe various bone tumors of the lower extremities is beyond the scope of this article, an attempt is made to provide a framework for a rational and comprehensive approach to these complicated but relatively uncommon lesions. Certain lesions with unique characteristics are discussed to facilitate the diagnostic process.

Soft tissue tumors of the lower extremities

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