Dynamic contrast-enhanced MR imaging in osteoid osteoma: relationships with clinical and CT characteristics.

OBJECTIVE: To correlate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) features to clinical and computed tomography (CT) morphological features of osteoid osteoma (OO). MATERIALS AND METHODS: Our institutional review board approved this retrospective study, waiving the need for informed consent. We included the 102 patients treated with interstitial laser ablation for histologically documented OO at our institution in 2008-2013. DCE-MRI variables were the time-enhancement pattern and rising slope (Sloperise) and CT variables were the bone and segment involved (OObone and OOsegment, respectively), OO location relative to the native cortex (OOcortex), nidus surface area, vessel sign, and largest neighboring-vessel diameter (Dmaxvessel). Descriptive statistics and correlations linking DCE-MRI findings to clinical and CT characteristics were computed. RESULTS: DCE-MRI showed early arterial peak enhancement in 95 (93%) cases, with a mean Sloperise of 9.30 ± 8.10. CT visualized a vessel sign in 84 (82%) cases with a mean Dmaxvessel of 1.10 ± 0.60 mm. By univariate analysis, Sloperise correlated significantly with pain duration and Dmaxvessel (r = 0.30, P = 0.003; and r = 0.22, P = 0.03; respectively). Analysis of variance showed that Sloperise correlated significantly with OObone (P < 0.001), with a steeper slope for OOs located in short or flat bones. CONCLUSION: This study suggests more abundant vascularization of OOs with long-lasting pain and location on short or flat bones.

[Stress fractures]. / Les fractures de contrainte.

In 1892, J. Wolff, an orthopedic surgeon, stated that the internal architecture and shape of a bone were related to the direction of stresses placed upon it. Conventional radiographs and MRI can demonstrate the adaptability of bones to stresses. Imaging also demonstrates that this adaptability has limitations, and that excessive stress may lead to fracture.

[Soft tissue tumors and pseudotumors of the foot and ankle]. / Tumeurs et pseudo-tumeurs des tissus mous de la région pied-cheville.

Soft tissue masses around the foot and ankle are frequent. While benign lesions are two times more frequent than malignant lesions, the latter still represent one third of all lesions. The main purpose of this article is to propose a systematic approach to the differential diagnosis of soft tissue tumors of the foot and ankle based on a combination of 5 elements: clinical history and physical examination, top 10 most frequent diagnoses, patient age, lesion location, and MRI features of the mass. Selected soft tissue tumors will be described and illustrated with emphasis on these 5 elements.

[Prostate MRI spectroscopy]. / Spectroscopie par résonance magnétique de la prostate.

MRI spectroscopy is a non invasive method for detecting active metabolites used as markers. Chorine and citrate are used for analyzing prostate cancer. MRI spectroscopy combines morphologic imaging and metabolic cartography. This combination allows a new approach for the diagnosis of prostate cancer in patients with negative biopsy and high Levels of PSA. With MRI spectroscopy the Local staging of prostate cancer has a better accuracy than with MRI alone. It can also be used for the diagnosis of residual disease and recurrence in patients treated with conservative therapy.

Complications of percutaneous vertebroplasty and their prevention.

Complications due to vertebroplasty may be divided into two categories whether or not they are related to polymethylmethacrylate (PMMA) cement leakage from the compressed vertebral body. PMMA leakage is a very frequent occurrence in vertebroplasty is also the main source of complications. Neurological complications are due to cement leakage into the spinal canal and less exceptionally into the intervertebral foramen. The transpedicular needle approach reduces the risk of cement leakage into the foramen. Pulmonary embolism of PMMA may occur when there is a failure to recognize venous migration of cement early during the procedure. Cortical destruction, presence of an epidural soft-tissue mass, highly vascularized lesions, and severe vertebral collapse are factors which increase the rate of complications, which is therefore much higher in metastatic than in osteoporotic vertebral collapse. Prevention of PMMA leakage-related complications is a multifactorial issue including procedure preparation, needle approach and placement, and cement application. The technical refinements which may help reduce the risk of PMMA leakage are reviewed in this article. Experimental data have shown that systemic reactions may occur during vertebroplasty in the absence of cement leakage. These reactions may be partly related to vascular embolism of bone marrow fat. Another controversial issue is a possible increase in the risk of vertebral collapse of adjacent vertebrae following vertebroplasty. Prospective randomized studies are needed to resolve this issue.

[Interventional lumbar spine radiology]. / Radiologie interventionnelle du rachis lombaire.

Three different techniques will be discussed. The first procedure is the biopsy of the lumbar vertebra or lumbar intervertebral disc for patients with tumors or infections of the lumbar spine. The different needles that can be used in function of consistency and location of the lesion will be shown. The transpedicular and posterolateral techniques will be described. Cementoplasty for tumors and selected patients with osteoporotic vertebral collapse generates much interest. The transpedicular and posterolateral techniques will be described. Indications and complications, more frequent in patients with tumors, will be reviewed. Finally, foraminal injections of steroids in patients with radicular symptoms secondary to degenerative change will be discussed. Techniques for needle placement will be reviewed. Results from these injections will also be reviewed.

[MRI appearance of a primary leiomyosarcoma of bone with epiphyseal involvement]. / Aspect IRM d'un cas de léiomyosarcome osseux primitif de localisation épiphysaire.

Primary leiomyosarcoma of bone is a rarely reported tumor of elderly subjects. It usually shows an aggressive osteolytic pattern on plain radiographs and involves predominantly the metaphyses of long bones. We report a case of primary leiomyosarcoma of bone, which is atypical by its epiphyseal location, a non-aggressive pattern on plain radiographs and its MR imaging features.

[Hajdu-Cheney syndrome: an unusual cause of acro-osteolysis]. / Le syndrome d'Hajdu-Cheney: une cause rare d'acro-ostéolyse.

We report a case of Hajdu-Cheney syndrome. This cranioskeletal dysplasia is characterized by band-like acro-osteolysis of the tufts middle thirds. Differential diagnosis of band-like acro-osteolysis are discussed.

Osteoid osteoma of the acetabulum. Three cases treated by percutaneous resection.

The acetabulum is a rare location for osteoid osteoma. Conventional surgery of such lesions may require either a large bone resection, an arthrotomy, or a hip dislocation. This report describes the technique and results of percutaneous lesion removal using computed tomography guidance in three osteoid osteomas of the acetabulum. Histologic confirmation was obtained in the three cases. The three patients experienced complete pain relief with a mean followup of 36 months.

Percutaneous removal of osteoid osteoma.

In most cases, osteoid osteomas can be removed through a percutaneous approach. The authors report their experience of percutaneous removal of osteoid osteomas under CT guidance. The literature on percutaneous treatments of osteoid osteomas is reviewed. The respective advantages of percutaneous removal and percutaneous destruction of the nidus using thermocoagulation or interstitial laser photocoagulation are discussed.

Magnetic resonance appearance of monoclonal gammopathies of unknown significance and multiple myeloma. The GRI Study Group.

STUDY DESIGN: A prospective multicenter study. OBJECTIVES: To evaluate the use of magnetic resonance imaging, in the differentiation between monoclonal gammopathies of unknown significance and multiple myeloma. SUMMARY OF BACKGROUND DATA: Although multiple myeloma has been studied extensively with magnetic resonance imaging, to the authors' knowledge, no study has evaluated the clinical interest of magnetic resonance imaging in the differentiation between monoclonal gammopathies of unknown significance and multiple myeloma. METHODS: The magnetic resonance examinations of the thoracolumbar spine in 24 patients with newly diagnosed monoclonal gammopathies of unknown significance were compared with those performed in 44 patients with newly diagnosed nontreated multiple myeloma. RESULTS: All findings on magnetic resonance examination performed in patients with monoclonal gammopathies of unknown significance were normal, whereas findings on 38 (86%) of the 44 magnetic resonance examinations performed in patients with multiple myeloma were abnormal. CONCLUSION: Magnetic resonance imaging can be considered as an additional diagnostic tool in differentiating between monoclonal gammopathies of unknown significance and multiple myeloma, which may be helpful when routine criteria are not sufficient. An abnormal finding on magnetic resonance examination in a patient with monoclonal gammopathies of unknown significance should suggest the diagnosis of multiple myeloma after other causes of marrow signal abnormalities are excluded. Magnetic resonance imaging also may be proposed in the long-term follow-up of monoclonal gammopathies of unknown significance when a new biologic or clinical event suggests the diagnosis of malignant monoclonal gammopathy.

-Computed tomography arthrography and tendon imaging of the ankle-. / Arthroscanner et ténoscanner de la cheville.

Ankle opacification dramatically increases the diagnostic value of CT examination of the foot and ankle. The procedure may be entirely performed on the CT table. The main results and indications of CT-arthrography of the ankle are presented. CT-tenography of the ankle which includes the opacification of a tendon sheath on the CT table, is also described.

-Lesser known stress fractures-. / Fractures de contrainte mal connues.

Stress fractures of the tibia may disclose a longitudinal orientation which is obvious at bone scanning; a mild periostosis may appear on plain films; CT demonstrates a radially-oriented fracture in one aspect of the diaphyseal cortex. A cortical dissection-like vertically oriented insufficiency fracture may involve the medial aspect of the femoral shaft underlying the lesser trochanter; the fracture is concentric to the femoral cortex at CT. Insufficiency fractures of the sacrum may be misdiagnosed on plain films; bone scanning displays a typical H-shaped increased uptake which is a specific pattern. Insufficiency fractures of the pubis may appear as tumoral bone destruction; however no soft tissue mass is present at CT which in addition demonstrates normal fat tissue abutting the osseous lesion.

Acute vertebral collapse due to osteoporosis or malignancy: appearance on unenhanced and gadolinium-enhanced MR images.

PURPOSE: To distinguish malignant from osteoporotic acute vertebral collapses. MATERIALS AND METHODS: Sixty-three osteoporotic and 30 malignant vertebral collapses were studied in 51 patients (aged 33-88 years) with T1-weighted magnetic resonance (MR) images (n=93), gadolinium-enhanced T1-weighted images (n=72), and T2-weighted images (n=53). RESULTS: Four findings were suggestive of osteoporosis: retropulsion of a bone fragment (10 osteoporotic cases vs 0 malignant cases), preservation of normal signal intensity on T1-weighted images (43 vs four), return to normal signal intensity after gadolinium injection (42 vs four) with horizontal bandlike patterns, and isointense vertebrae on T2-weighted images (28 vs two). Six findings were suggestive of malignancy: convex posterior cortex (21 malignant cases vs four osteoporotic cases), epidural mass (24 vs 0), diffuse low signal intensity within the vertebral body on T1-weighted images (23 vs 12) and in the pedicles (24 vs four), high or inhomogeneous signal intensity after gadolinium injection (17 vs 0) and on T2-weighted images (17 vs 0). CONCLUSION: Gadolinium-enhanced and unenhanced MR images are useful in the differentiation of vertebral collapses.

Acute vertebral collapse: CT findings in benign and malignant nontraumatic cases.

PURPOSE: The value of computed tomography (CT) for differentiating benign from malignant causes of nontraumatic acute vertebral collapse (AVC) (associated with pain of less than 3 months duration) was evaluated. MATERIALS AND METHODS: The CT findings of 34 benign (osteoporotic) and 32 malignant (metastatic or myelomatous) nontraumatic AVCs were compared. RESULTS: The following CT findings were significantly more frequent in benign AVCs: cortical fractures of the vertebral body without cortical bone destruction, retropulsion of a bone fragment of the posterior cortex of the vertebral body into the spinal canal, fracture lines within the cancellous bone of the vertebral body, an intravertebral vacuum phenomenon, and a thin diffuse paraspinal soft-tissue mass (PSTM). The following CT findings were significantly more frequent in malignant AVCs: destruction of the anterolateral or posterior cortical bone of the vertebral body, destruction of the cancellous bone of the vertebral body, destruction of a vertebral pedicle, a focal PSTM, and an epidural mass. CONCLUSION: CT can help distinguish benign from malignant causes of nontraumatic AVC.

[Vertebral vacuum phenomena]. / Vides rachidiens.

The spinal vacuum phenomenon is a collection of gas within the disk space, the vertebral body, the apophyseal joint or the spinal canal. The intradiscal vacuum phenomenon is frequently observed in degenerative disk disease and crystal-induced diskopathy. This has obvious significance to the radiologist, who, on observing a narrowed disk space or collapsed vertebral body, might otherwise consider infectious or neoplastic spondylitis, a likely possibility. The presence of vacuum phenomenon militates against the diagnosis of infection or tumor.

[Lumbar puncture with a fine needle]. / Ponction lombaire à l'aiguille fine.

26-Gauge fine needle for lumbar puncture allows lower rate and intensity of post lumbar puncture syndrome. This technique drammatically decreases discomfort in patients who undergo myelography and helps in keeping this imaging modality indicated when necessary.

[Current imaging of spondylolisthesis by isthmic lysis]. / Imagerie actuelle du spondylolisthésis par lyse isthmique.

Unilateral spondylolytic spondylolisthesis may cause lateral tilt of the overlying spinous processes towards the normal isthmus on PA views. Bilateral spondylolytic spondylolisthesis is generally located at the L5-S1 level. The vertebral shift is usually moderate. Instability at the level of spondylolisthesis may be demonstrated by stress lateral views but is uneasy to quantify. In case of sciatica associated to spondylolisthesis, foraminal stenosis is probably the most frequent cause but foraminal compression of the spinal ganglion is difficult to assess on imaging.

[Radioguided injection of the lumbar and the first sacral intervertebral foramina]. / Infiltration radioguidée des trous de conjugaison lombaires et du premier trou sacré.

Lumbar foraminal injection under fluoroscopic guidance is indicated either for a diagnostic purpose to determine which nerve root is painful or for a selective steroid injection. Lumbar foraminal approach is based on that of the posterolateral extradural diskography. Selective puncture of the first sacral foramen under fluoroscopic guidance may be indicated for the treatment of sacral symptomatic meningeal cysts, a very unfrequent lesion.

[Fibrous dysplasia of bone and osteofibrous dysplasia. Focusing]. / Dysplasie fibreuse des os et dysplasie ostéo-fibreuse. Mise au point.

This is a review article on fibrous dysplasia of bone. All aspects of this condition including, macroscopic and histologic findings, lesion distribution, clinical, radiological and biological findings as well as evolution and treatment are discussed. A classification of skeletal lesions based on then appearance on plains films and computed tomography is proposed; 3 radiological types are differentiated: non-expanding bone lesions, expanding lesions with a thick periosteal reaction and expanding lesions with a thin periosteal shell. Main features of osteofibrous dysplasia are also discussed.