Magnetic Resonance-Guided High-Intensity Focused Ultrasound Ablation of Osteoid Osteoma: A Case Series Report.

Osteoid osteoma is painful benign tumor. The aim of this study was to report our initial experience using magnetic resonance-guided focused ultrasound to treat osteoid osteomas. This retrospective single-center study included four patients treated with magnetic resonance-guided focused ultrasound. They presented with severe pain with reduced quality of life and a poor response to clinical treatment. The pre- and post-treatment evaluation comprised computed tomography and magnetic resonance imaging and focused on quality of life and the impact of pain on daily activities. After treatment, three patients had complete pain resolution with no recurrence. One patient had a recurrence of symptoms after 2 wk and underwent a new successful treatment with increased energy levels. On average, 13 sonications were administered (8-18 sonications/treatment) with an average energy of 2,003 J (range: 1,063-3,522 J). Magnetic resonance-guided focused ultrasound appears to be a feasible, tolerable and effective treatment in selected patients with osteoid osteomas.

MR imaging of entrapment neuropathies of the lower extremity. Part 2. The knee, leg, ankle, and foot.

Entrapment neuropathies of the knee, leg, ankle, and foot are often underdiagnosed, as the results of clinical examination and electrophysiologic evaluation are not always reliable. The causes of most entrapment neuropathies in the lower extremity may be divided into two major categories: (a) mechanical causes, which occur at fibrous or fibro-osseous tunnels, and (b) dynamic causes related to nerve injury during specific limb positioning. Magnetic resonance (MR) imaging, including high-resolution MR neurography, allows detailed evaluation of the course and morphology of peripheral nerves, as well as accurate delineation of surrounding soft-tissue and osseous structures that may contribute to nerve entrapment. Familiarity with the normal MR imaging anatomy of the nerves in the knee, leg, ankle, and foot is essential for accurate assessment of the presence of peripheral entrapment syndromes. Common entrapment neuropathies in the knee, leg, ankle, and foot include those of the common peroneal nerve, deep peroneal nerve, superficial peroneal nerve, tibial nerve and its branches, and sural nerve.

MR imaging of iliopsoas musculotendinous injuries.

The literature describing iliopsoas compartment injuries is based on case reports and small patient series, mostly in the orthopedic literature.Nevertheless, in recent years, there has been a growing recognition of these injuries. Because many intra-articular and extra-articular bony and soft tissue injuries in the groin may clinically mimic each other, because two or more pathologic entities may coexist, and because athletes are highly motivated to continue with their physical activity, diagnosis of iliopsoas injury is often delayed. Thus, cross-sectional imaging is highly important. MR imaging is most accurate for diagnosing nondynamic diseases of the iliopsoas compartment as well as for ruling out other abnormalities of the hip joint and surrounding structures. When a snapping hip is being investigated or corticosteroid injection is warranted, US can be of help in providing a dynamic study and by guiding the injection.