Postoperative Magnetic Resonance Imaging of the Knee Ligaments.

In this article, we describe the postoperative appearances of the reconstructed ligaments of the knee focusing on the anterior cruciate ligament (ACL). The expected evolving signal alterations of the graft over time are also reviewed. The postoperative appearance of the ligamentous reconstruction in patients with multiligamentous knee injuries (MLKI) and isolated PCL tears are also discussed.

Magnetic Resonance Imaging of Nerve Tumors.

Nerve tumors are uncommon soft tissue neoplasms predominantly arising from peripheral nerve sheath and Schwann cells. We review the manifestations of benign peripheral nerve sheath tumors, concentrating on distinguishing imaging features of schwannomas versus neurofibromas with an emphasis on treatment implications. Nevertheless, there is often an overlap between the imaging presentation of these two conditions, making the accurate radiologic diagnosis challenging. Therefore, tissue sampling is often needed for a definitive histologic diagnosis. Treatment planning largely depends on symptoms, location of the lesion, and underlying risk factors. Three major syndromes, neurofibromatosis type 1, type 2, and schwannomatosis, predispose patients to peripheral nerve sheath tumors (PNSTs), with particular concern about the malignant subtype expression. In patients with suspected PNSTs, correlation of imaging findings with clinical findings and genetic tests is helpful for a more accurate diagnosis and disease management. Some imaging features on magnetic resonance imaging and fluorodeoxyglucose-positron emission tomography can be helpful to differentiate malignant from benign subtypes.

Focal reactive periostitis ossificans in a long bone: radiologic and pathologic findings.

Florid reactive periostitis ossificans (FRPO) is a benign juxta-cortical lesion of unknown etiology which most commonly occurs in the hands and feet. We report the radiographic, CT, and MR features of a pathologically confirmed FRPO in the distal femur, a location in which only a handful of cases has been reported. A 26-year-old male who presented with distal thigh pain initially underwent radiograph and CT, which illustrated a well-circumscribed, ossified lesion associated with the cortex of the femur without contiguity with the medullary canal. A subsequent MRI demonstrated heterogeneous signal intensity corresponding to the ossified portion of the lesion with a T2 hyperintense cartilaginous cap and surrounding edema. The lesion was surgically excised and pathologic diagnosis of FRPO, a mixture of osteoid, mature bone, cartilage and fibrous tissue, with associated inflammatory cells, was confirmed. Follow up four months after surgery revealed significant improvement in the patient's pain.

Imaging of meniscal allograft transplantation: what the radiologist needs to know.

Meniscal allograft transplantation is an emerging surgical option for younger patients with symptomatic meniscal deficiency, which aims to restore anatomic biomechanics and load distribution in the knee joint, and by so doing to potentially delay accelerated osteoarthritis. In this review article, we summarize the structure and biomechanics of the native meniscus, describe indications and procedure technique for meniscal allograft transplantation, and demonstrate the spectrum of expected postoperative imaging and role of imaging to identify potential complications.

Pseudomyogenic hemangioendothelioma-A case report and review of the literature.

Pseudomyogenic hemangioendothelioma (PMH) of bone is a very rare tumor and frequently presents at multiple locations. PMH is difficult to diagnose by imaging and histopathologic features. Various and partially discordant imaging findings have been reported in case reports and small case series. We report a case of a 63-year-old man with PMH isolated to the sacrum, presenting with chronic intermittent buttock pain that was incidentally identified on imaging for acute pancreatitis. We believe that learning about PMH of bone will help to include this disease in the differential diagnosis of lytic lesions of the sacrum. Becoming aware of the various and sometimes discordant imaging findings of this rare entity is important and helpful for radiologists, pathologists, and orthopedic surgeons.