MRI of Soft-Tissue Tumors: What to Include in the Report.

MRI serves as a critical step in the workup, local staging, and treatment planning of extremity soft-tissue masses. For the radiologist to meaningfully contribute to the management of soft-tissue masses, they need to provide a detailed list of descriptors of the lesion outlined in an organized report. While it is occasionally possible to use MRI to provide a diagnosis for patients with a mass, it is more often used to help with determining the differential diagnosis and planning of biopsies, surgery, radiation treatment, and chemotherapy (when provided). Each descriptor on the list outlined in this article is specifically aimed to assist in one or more facets of the overall approach to soft-tissue masses. This applies to all masses, but in particular sarcomas. Those descriptors are useful to help narrow the differential diagnosis and ensure concordance with a pathologic diagnosis and its accompanying grade assignment of soft-tissue sarcomas. These include a lesion's borders and shape, signal characteristics, and contrast enhancement pattern; the presence of peritumoral edema and peritumoral enhancement; and the presence of lymph nodes. The items most helpful in assisting surgical planning include a lesion's anatomic location, site of origin, size, location relative to a landmark, relationship to adjacent structures, and vascularity including feeding and draining vessels. The authors provide some background information on soft-tissue sarcomas, including their diagnosis and treatment, for the general radiologist and as a refresher for radiologists who are more experienced in tumor imaging. ©RSNA, 2024 See the invited commentary by Murphey in this issue.

VIDEO: Dynamic Ultrasound for Snapping Hip Syndrome.

OBJECTIVE. The purpose of this video article is to review the dynamic sonographic assessment of snapping hip syndrome. The video focuses on the extraarticular forms of snapping hip and discusses their possible causes, ultrasound features, and treatment options. The dynamic sonographic technique for evaluating snapping hip syndrome is shown with live scanning videos. CONCLUSION. Dynamic ultrasound is well suited for the assessment of snapping hip syndrome and is essential for confirming the clinical diagnosis of the condition.

Normal Skeletal Maturation and Imaging Pitfalls in the Pediatric Shoulder.

A growing number of magnetic resonance (MR) imaging studies of the shoulder are being performed as a result of greater and earlier participation of children and adolescents in competitive sports such as softball and baseball. However, scant information is available regarding the MR imaging features of the normal sequential development of the shoulder. The authors discuss the radiographic and MR imaging appearances of the normal musculoskeletal maturation patterns of the shoulder, with emphasis on (a) development of secondary ossification centers of the glenoid (including the subcoracoid and peripheral glenoid ossification centers); (b) development of preossification and secondary ossification centers of the humeral head and the variable appearance and number of the secondary ossification centers of the distal acromion, with emphasis on the formation of the os acromiale; (c) development of the growth plates, glenoid bone plates, glenoid bare area, and proximal humeral metaphyseal stripe; and (d) marrow signal alterations in the distal humerus, acromion, and clavicle. In addition, the authors discuss various imaging interpretation pitfalls inherent to the normal skeletal maturation of the shoulder, examining clues that may help distinguish normal development from true disease (eg, osteochondral lesions, labral tears, abscesses, fractures, infection, tendon disease, acromioclavicular widening, and os acromiale). Familiarity with the timing, location, and appearance of maturation patterns in the pediatric shoulder is crucial for correct image interpretation.

Skeletal development of the proximal humerus in the pediatric population: MRI features.

OBJECTIVE: The purpose of this study was to provide a guideline of normal MRI developmental anatomy of the proximal humerus in a growing child. MATERIALS AND METHODS: Retrospective interpretation of 83 consecutive MRI studies of shoulders in children 2 months to 17 years old was performed in consensus by two radiologists. The following variables were documented: presence, number, and fusion of secondary ossification centers; appearance and closure of the growth plate; presence of the metaphyseal stripe; and proximal metaphyseal marrow signal intensity. RESULTS: Preossification centers were seen in 2- and 4-month-old patients. Secondary ossification centers appeared in the medial humeral head and greater tuberosity at 4 and 10 months, respectively, originally depicting red marrow and later converting to yellow marrow. A separate lesser tuberosity ossification center was not seen. The ossification centers began fusing by 3 years and gradually conformed to the final shape of the proximal humerus. Ossification was completed by 13 years. The multilaminar growth plate initially had a flat and smooth contour that progressively became irregular and pyramidal, closing at 17 years. The metaphyseal stripe was noted at infancy and disappeared by 15.5 years. The metaphyseal marrow signal intensity was diffusely low in infants but, with conversion to yellow marrow, showed proximal metaphyseal bright patchy or linear signal-intensity, eventually disappearing by 17 years. CONCLUSION: The postnatal skeletal development of the proximal humerus in the pediatric population follows distinctive sequential patterns of maturation, which can serve as a guideline for interpreting MRI studies in children.

Skeletal development of the glenoid and glenoid-coracoid interface in the pediatric population: MRI features.

OBJECTIVE: To assess the MRI appearance of normal skeletal development of the glenoid and glenoid-coracoid interface in the pediatric population. To the best of our knowledge, this has not yet been studied in detail in the literature. MATERIALS AND METHODS: An IRB-approved, HIPAA-compliant retrospective review of 105 consecutive shoulder MRI studies in children, ages 2 months to 18 years was performed. The morphology, MR signal, and development of the following were assessed: (1) scapular-coracoid bipolar growth plate, (2) glenoid and glenoid-coracoid interface secondary ossification centers, (3) glenoid advancing osseous surface. RESULTS: The glenoid and glenoid-coracoid interface were identified in infancy as a contiguous, cartilaginous mass. A subcoracoid secondary ossification center in the superior glenoid was identified and fused in all by age 12 and 16, respectively. In ten studies, additional secondary ossification centers were identified in the inferior two-thirds of the glenoid. The initial concavity of the glenoid osseous surface gradually transformed to convexity, matching the convex glenoid articular surface. The glenoid growth plate fused by 16 years of age. Our study, based on MRI, demonstrated a similar pattern of development of the glenoid and glenoid coracoid interface to previously reported anatomic and radiographic studies, except for an earlier development and fusion of the secondary ossification centers of the inferior glenoid. CONCLUSIONS: The pattern of skeletal development of the glenoid and glenoid-coracoid interface follows a chronological order, which can serve as a guideline when interpreting MRI studies in children.

MR Imaging of Benign Soft Tissue Tumors: Highlights for the Practicing Radiologist.

The overwhelming majority of soft tissue masses encountered on routine imaging are incidental and benign. When incidental, the radiologist is usually limited to routine MR imaging sequences, often without contrast. In these situations, there are typical imaging features pointing to a single diagnosis or limited differential diagnosis. Although these imaging features can be helpful, many lesions are nonspecific and may require contrast administration, evaluation with other imaging modalities, follow-up imaging, or biopsy for diagnosis. This article will provide an overview of the most commonly encountered benign soft tissue masses along with some of their characteristic MR imaging features.

Intraneural Hemangioma: Case Report of a Rare Tibial Nerve Lesion.

An intraneural hemangioma is a rare, benign mesodermal lesion. We present a case of a three-year-old female with the inability to straighten her right knee and fullness over the right popliteal fossa for one year. Magnetic resonance imaging (MRI) demonstrated a T2 hyperintense lesion of the popliteal fossa, within the tibial nerve. The patient underwent an uncomplicated right knee excisional biopsy, which confirmed the diagnosis of an intraneural hemangioma. Although rare, an intraneural hemangioma should be considered in the differential diagnosis of a soft tissue lesion located in the expected course of a peripheral nerve.