J. E. Vandevenne

New concepts in understanding evolution of desmoid tumors: MR imaging of 30 lesions

Abstract The objective of this study was to evaluate the appearance and the natural evolution of desmoid tumors on MR imaging, given histologic correlation. The MR images of 30 desmoids (20 primary and 10 recurrent) in 26 patients were scored for a multiplicity of morphological parameters, signal intensity (SI) on different pulse sequences, and behavior after contrast administration. Natural evolution was evaluated in 2 primary and 3 recurrent lesions, and correlated with evolution on histologic specimens. Desmoid tumors are mostly found in muscles of shoulder and hip girdle and are often fusiform with partially ill-defined margins. Rare subcutaneous desmoids have a more stellar morphology. Variable amounts of low-SI areas are present on all sequences. On T1-weighted images (T1-WI), most lesions are near homogeneous and isointense to muscle, whereas on T2-WI they are more heterogeneous with an overall SI equal to or slightly lower than fat. Histologic correlation reveals that SI on T2-WI cannot be explained solely by cellularity. After initial growth, spontaneous evolution of desmoids is characterized by shrinking and an increase in low-SI areas on T2-WI. While distal lesions shrink, the more recent lesions in asynchronous multicentric desmoids have a tendency to develop proximally in the same limb, and should not be confused with recurrences. Fast growth, extracompartmental spread, and bone involvement are often seen in recurrences. Follow-up MR imaging of desmoids indicates natural regression of desmoids and more aggressive behavior of recurrences, which may justify a more conservative therapeutic approach.

Magnetic resonance imaging of soft tissue tumors.

Abstract. This article outlines the ability of MR imaging in staging, grading, tissue characterization, and posttherapeutic surveillance of soft tissue tumors. Well-known staging parameters, such as extent, relationship with adjacent structures, and detection of intralesional necrosis, are used in the MR protocol for locoregional staging. Bone scintigraphy and high-resolution CT scan of the lungs are best methods for ruling out metastatic spread. A variety of (solitary or combinations of) grading parameters are described in the radiological literature. The role of MR imaging is to afford recognition of these lesions that need further aggressive work-up, excluding all others. Despite controversial reports, the definite role of MR imaging in grading of soft tissue tumors seems to become established. As for grading, a lot of individual imaging characteristics used for tissue characterization have low sensitivity, but combinations of parameters (age, site, signal intensities) are more useful and often allow to predict a specific diagnosis or to narrow down the list of differential diagnoses. Local recurrences of soft tissue tumors are frequent and can be detected accurately by an easy-to-use MR algorithm.

MR imaging of clear cell sarcoma (malignant melanoma of the soft parts): A multicenter correlative MRI-pathology study of 21 cases and literature review

Abstract Objective. To evaluate MR imaging and pathology findings in order to define the characteristic features of clear cell sarcoma of the soft tissues (malignant melanoma of the soft parts). Design and patients. MR examinations of 21 patients with histologically proven clear cell sarcoma of the musculoskeletal system were retrospectively reviewed and assessed for shape, homogeneity, delineation, signal intensities on T1- and T2-weighted images, contrast enhancement, relationship with adjacent fascia or tendon, secondary bone involvement, and intratumoral necrosis. In 19 cases the pathology findings were available for review and for a comparative MR-pathology study. Results. On T1-weighted images, lesions were isointense (n=3), hypointense (n=7) or slightly hyperintense to muscle (n=11). Immunohistochemical examination was performed in 17 patients. All 17 specimens showed positivity for HMB-45 antibody. In nine of 11 lesions with slightly increased signal intensity on T1-weighted images, a correlative MR imaging-pathology study was possible. All nine were positive to HMB-45 antibody. Conclusions. Clear cell sarcoma of the musculoskeletal system often has a benign-looking appearance on MR images. In up to 52% of patients, this lesion with melanocytic differentiation has slightly increased signal intensity on T1-weighted images compared with muscle. As the presence of this relative higher signal intensity on T1-weighted images is rather specific for tumors displaying melanocytic differentiation, radiologists should familiarize themselves with this rare entity and include it in their differential diagnosis when confronted with a well-defined, homogeneous, strongly enhancing mass with slightly higher signal intensity compared with muscle on native T1-weighted images.

MR features of peripheral nerve sheath tumors: can a calculated index compete with radiologist's experience?

Abstract The aims of this study were, firstly, to provide a formula (neurogenic index) based on MR characteristics used in daily routine for predicting whether a soft tissue tumor is neurogenic or not, secondly, to test prospectively the performance of this formula, and thirdly, to compare this performance with that of radiologists experienced in MR imaging of soft tissue tumors. Retrospectively, MR images of 70 neurogenic and 70 non-neurogenic soft tissue tumors were evaluated in random order by two teams of two observers each. A neurogenic index (NI) was calculated based on those MR parameters that showed no or minor interobserver variability. Subsequently, three investigators in concert used the NI in a validation group of 15 neurogenic and 22 non-neurogenic soft tissue tumors. The same team, based on their own experience, tried to differentiate in the same validation group neurogenic from non-neurogenic soft tissue tumors. This was expressed in a subjective score (SS). Sensitivity, specificity, and predictive values were calculated. NI comprised spread (intra- or extracompartmental), distribution, fluid–fluid levels, homogeneity on T2-weighted images (WI), highest signal intensity (SI) on T1WI, lowest SI on T2WI, and delineation on T2WI. In the validation group, NI had a sensitivity of 88.6 %, a specificity of 52.0 %, a positive predictive value (PPV) of 54.1 %, and a negative predictive value (NPV) of 84.6 % for neurogenic tumors. The subjective score SS was superior and had a sensitivity of 93.3 %, a specificity of 77.2 %, a PPV of 73.7 %, and a NPV of 94.4 %. Our NI was less accurate than the SS; however, the low number of false-negative diagnoses for neurogenic tumors warrants continued efforts in development of neural networks.

Subcutaneous granuloma annulare: MR imaging and literature review

Abstract. Subcutaneous granuloma annulare (SGA) is little known to radiologists. Better knowledge of this lesion may prompt accurate diagnosis. A typical case is presented with plain radiography, ultrasound and MR imaging, and is confirmed by histology. When an otherwise healthy child presents with a rapidly growing, solitary, nontender, subcutaneous soft tissue mass, located on the scalp or extensor aspect of the limbs, that radiologically presents as an indistinct radiodense and hypoechoic mass, isointense to muscle on T1- and slightly hypointense to fat on T2-weighted MR images, without calcifications, bone involvement or extracompartmental invasion, SGA should be suspected.

Peroneal neuropathy after weight loss: a high-resolution ultrasonographic characterization of the common peroneal nerve

ObjectiveThe objective of this study was to use in vivo ultrasonographic imaging to analyze the common peroneal nerve in controls and patients who were diagnosed with peroneal neuropathy (PN) due to significant weight loss. We also looked for a relationship between weight loss (magnitude) and the occurrence of PN.Materials and methodsFifty controls and six patients who were diagnosed with PN after losing a significant amount of weight were examined by means of ultrasonography (US). On the US images, the structure and reflectivity of the nerve were analyzed. Correlations were made between the ultrasonographic measurements and the body mass index (BMI) of controls. In PN patients, these ultrasonographic parameters were compared between the normal and pathological legs.ResultsBMI was positively correlated with the transverse cross-sectional area of the nerve and fibular tunnel in controls. In controls with a high BMI, the peroneal nerve appeared thicker and the US reflectivity of the nerve was higher. A lower US reflectivity was observed in the pathological legs of the six patients who developed PN after weight loss.ConclusionThe transverse cross-sectional area and reflectivity of the peroneal nerve on the US images could be viable tools in the diagnosis of PN after weight loss.

Imaging of Soft Tissue Tumors in the Pediatric Patient

The presence of a soft tissue mass in children is of concern to parents and physicians. Fortunately, these masses are rare and usually benign or pseudotumoral. When dealing with malignant soft tissue tumors, therapeutic options and long-term survival are strongly related to the disease stage at the time of diagnosis. Therefore, when children present with indeterminate or persisting symptoms and posttraumatic, metabolic, or infectious disorders have been ruled out, one should perform dedicated imaging studies (conventional radiography, computed tomography [CT], or both; sonography; magnetic resonance [MR] imaging) to exclude the possibility of a nonpalpable soft tissue mass or to characterize the mass when present. An overview of the use of the different imaging modalities for evaluating soft tissue tumors in the pediatric patient is presented. Because of the numerous benign, malignant, and pseudotumoral soft tissue masses that are often encountered in children, clinical, histologic, and imaging features are presented as concise tables.

Insulinoma associated with liver lesions: value of mr imaging

We report on a middle-aged woman who presented with clinical and biochemical findings of insulinoma. Preoperative evaluation by ultrasound, CT, and angiography located the pancreatic lesion but also revealed two focal liver lesions. The latter were interpreted as metastases. MR imaging with injection of superparamagnetic iron oxide particles not only localized the insulinoma but proved to be the only noninvasive technique capable to exclude presence of liver metastases preoperatively. This reversed management to minimal laparascopic surgery. Recent literature of preoperative imaging evaluation of insulinoma and focal liver lesions is discussed.

Multiple growing fractures and cerebral venous anomaly after penetrating injuries : delayed diagnosis in a battered child

Abstract A growing fracture usually results from a skull fracture with dural tear after blunt head trauma during infancy. We present a case of child abuse with multiple growing fractures resulting from penetrating head trauma by scissors. MR imaging confirmed the presence of growing fractures and revealed a presumably post-traumatic venous anomaly (occluded left cavernous sinus and aberrant posterior venous drainage via the internal cerebral veins). Diagnosis of the growing fractures and venous anomaly was delayed until the age of 15 years. Medical expertise should be more readily available to battered children, and MR imaging is advocated in growing skull fracture to exclude associated post-traumatic brain lesions.

Bare lymphocyte syndrome: imaging findings in an adult

Abstract Bare lymphocyte syndrome (BLS) is a rare primary immune disorder characterized by defective expression of human leukocyte antigen (HLA) on lymphocytes, often resulting in extensive and recurrent multi-organ infections. We describe a previously undiagnosed case of an adult woman who presented with radiological findings of severe bronchiectases, near-total granulomatous destruction of facial bones, and osteomyelitis. Diagnosis of BLS should be considered when evaluating children with unexplained bronchiectases or adults with long history of chronic multi-organ infections.