[Imaging of cartilage. Current status and prospects]. / Imagerie du cartilage. Etat actuel et perspectives.

This work describes the composition, organisation, metabolism, biomechanical and physiologic properties of normal cartilage. The initial involution process, of biochemical nature, preceding by far the morphological changes is described as well as the degenerative, inflammatory and traumatic pathogenesis. The modern cartilage imaging techniques are described with emphasis on MRI.

Imaging in reflex sympathetic dystrophy.

The diagnosis of reflex sympathetic dystrophy (RSD) relies on clinical evaluation, scintigraphy or MR imaging, and routine radiographs. Because RSD has variable manifestations with a strong psychogenic overlap, it is desirable to have a noninvasive test to determine the presence of RSD to allow for appropriate treatment. MR imaging allows a differential diagnosis between RSD and other bone lesions. It proves to be a reliable technique in showing and characterizing RSD better than radiographic examination and radionuclide study.

Facet joints diseases.

A review of the normal anatomy, developmental abnormalities, traumas and disorders affecting the facet joints is provided, with a recall of the major imaging modalities.

Magnetic resonance imaging for irreducible posterolateral knee dislocation.

Magnetic resonance imaging (MRI) of an irreducible knee dislocation can help physicians evaluate associated bone and ligamentous lesions. However, caution should be taken when interpreting the images because the capsuloligamentous interposition seen in irreducible knee dislocations may be misdiagnosed as a meniscal lesion.

BOP: biocompatible osteoconductive polymer: an experimental approach.

BOP (biocompatible osteoconductive polymer) is a material proposed for osteosyntheses and for filling of bone defects in orthopaedics, neurosurgery and stomatology. It is a composite made of a copolymer of N-vinylpyrrolidone and methylmethacrylate, of polyamide-6 fibers and of calcium gluconate. The histological investigation includes the study of 30 intact rabbit femurs instrumented with a BOP rod, as well as the study of organs of the reticuloendothelial system. The currently available results show the absence of toxicity on hematopoietic tissue. Zones of osteoblastic activity surround the rods, coupled with an osteoclastic reaction which may result in the partial fragmentation of the polyamide fibers and its incorporation in the newly formed bone. We also observed the encapsulation of the material. The biomechanical approach investigated the mechanical properties of the material in bending and in shear. The radiological aspects of the investigation consisted of computerized axial tomography of the implanted femurs to measure density at the bone-implant interface.

Fracture of the posterior aspect of the lateral tibial plateau: radiographic sign of anterior cruciate ligament tear.

Plain radiographs obtained in 25 patients with acute anterior cruciate ligament (ACL) tears detected with magnetic resonance imaging were retrospectively evaluated to identify associated bone lesions. Fracture of the posterior part of the lateral tibial plateau (LTP) was seen in 11 patients, impacted fracture of the lateral femoral condyle (LFC) in two, lateral tibial rim fracture (Segond fracture) in three, and avulsion fracture of the tibial attachment of the ACL in two. The latter three fractures have been associated with an ACL tear. Conversely, fractures of the posterior part of the LTP have not been associated with ACL tear and are recognizable on plain radiographs. Impaction of the LFC on the LTP and avulsion of the posterior tibial capsular junction may account for the association of the fracture of the LTP with the acute ACL tear. This type of fracture represents the most frequent indirect sign of ACL tear seen on plain radiographs.

Transverse geniculate ligament of the knee: appearance and frequency on plain radiographs.

The aims of the study were to determine the frequency of visualization of the normal transverse geniculate ligament (TGL) of the knee on lateral plain radiographs with magnetic resonance imaging (MRI) as a reference, and to determine features that make this ligament apparent on plain radiographs. 50 consecutive lateral plain radiographs and sagittal T1-weighted images of corresponding knees were evaluated prospectively. A TGL was considered visualized on plain radiographs when an opacity of soft-tissue density was apparent in the posterior part of the Hoffa's fat pad. The TGL was identified in 29 of the 50 (58%) sagittal MR images; a TGL was observed on the lateral plain radiographs of six patients (12%). Correlation with the MR images showed that, when visualized on plain radiographs, the ligament is at least 3 mm thick and completely surrounded by fat. Our study shows that the TGL is a normal variant that can be recognized frequently on lateral plain radiographs of the knee.

Ultrasound evaluation of soft tissue tumors.

Because of its availability, ultrasound should be the preferred initial modality for the evaluation of palpable superficial masses. Most ultrasound units are equipped with high frequency probes that allow superficial focalization. The differential diagnosis of soft tissue masses and the sonographic features of some benign and malignant soft tissue lesions are reviewed in this article. After an initial ultrasound evaluation confirming the presence of a tumor, the need for and the role of other imaging modalities can be determined. In selected cases ultrasound may obviate the need for further imaging. MRI and CT should be reserved for cases in which sonography fails to establish a specific diagnosis or to demonstrate the limits of the soft tissue mass.

Simultaneous neurofibroma and schwannoma of the sciatic nerve.

The authors report a case of simultaneously occurring neurofibroma and schwannoma of the sciatic nerve and discuss the complementary aspects of MR and US. The schwannoma was well-defined and showed distal enhancement on sonographic evaluation, whereas the neurofibroma was ill-defined; both tumors were hypoechoic. T1- and T2-weighted MR images revealed similar signal characteristics of the two tumors, but intense enhancement following administration of gadolinium-DTPA distinguished the schwannoma from the neurofibroma.

Relationship between magnetic resonance imaging and histologic findings by bone biopsy in nontraumatic osteonecrosis of the femoral head.

To attest the validity of magnetic resonance imaging (MRI) to evaluate the pathophysiology in nontraumatic osteonecrosis (ON) of the femoral head, we attempted to correlate the different MRI patterns with the histology in cases of early stages. We used not only the T1 and T2 pulse sequences, but also the T1 sequence after gadolinium-DTPA to demonstrate the presence of vascularization. Studying 24 core biopsies from 16 hips (9 patients), we explored the MRI presentations that corresponded to the main histologic findings of the different trabecular bone and bone marrow conditions. Histologic findings including trabecular bone necrosis and bone marrow necrosis represented by amorphous eosinophilic debris presented a low T1 signal intensity without enhancement after intravenous gadolinium injection and a low T2 signal intensity. Trabecular bone necrosis associated with mummified fat cells presented a normal T1 and T2 signal intensity. Trabecular bone necrosis with fibrosis filling the intertrabecular spaces had a low T1 signal intensity that was enhanced by gadolinium and had an intermediate T2 signal intensity. Bands of fibrosis without trabecular bone as seen in fracture zones showed a low T1 signal intensity that was enhanced by gadolinium with a high T2 signal intensity. Thickened trabecular bone with fibrosis as found in creeping substitution areas had also a low T1 signal enhanced by gadolinium, but the T2 signal intensity was low. Farther from the necrotic area, despite normal trabecular bone, we found some patchy necrosis of the bone marrow without any modification of the normal T1 and T2 MRI patterns.(ABSTRACT TRUNCATED AT 250 WORDS)

Gadolinium-DOTA enhanced MR imaging of prostatic lesions. Preliminary results on 14 cases.

Fourteen patients with prostatic carcinoma, benign prostatic hyperplasia, or chronic granulomatous prostatitis underwent gadolinium-DOTA enhanced magnetic resonance imaging of the prostate. Gadolinium-DOTA was administered intravenously in a dosage of 0.1 mmol/kg body weight. All studies were performed on a superconductive 1.5-T system. As compared to noncontrast T1- and T2-weighted images, Gd-DOTA enhanced T1-weighted images were useful in distinguishing malignant tumor from granulomatous prostatitis in one case, but were uncontributive to the differentiation between carcinoma and benign prostatic hyperplasia.

Transverse geniculate ligament of the knee: appearance at plain radiography.

Visualization of the transverse geniculate ligament of the knee in four patients is described. This normal variant was seen on lateral plain radiographs as a small, rounded opacity surrounded by fatty tissue and located anterior to the knee joint. Magnetic resonance imaging helped confirm this image to be that of the transverse geniculate ligament.

Post-myelographic meningeal irritation with iohexol.

A 45-year-old woman developed signs of meningeal irritation after myelography with iohexol. Her condition improved very quickly (after antibiotic treatment). Rapid improvement, absence of pathogenic organisms in the pre-treatment CSF culture, the level of CSF pleocytosis and protein were in favor of chemical meningitis.

Pulmonary sequestration-like anomaly presenting as a spontaneously resolving mass.

A premature baby boy presented at birth with respiratory distress. A right lower lobe opacity was found on chest X-ray. Pulmonary sequestration was the diagnosis suggested by ultrasound. The size of the mass decreased on subsequent examinations. 4 months later X-rays and sonography failed to demonstrate any remaining mass. This case illustrates another example of involutive pathology and suggests that not all pulmonary sequestration-like anomalies should be operated on.

Cysts of the prostate and seminal vesicles: MR imaging findings in 11 cases.

Cysts of the prostate and seminal vesicles are confusing abnormalities because they are uncommon and their origin is uncertain. Several approaches to diagnosis have been used, most recently CT and transrectal sonography. In this study, we investigated the value of MR imaging in the diagnosis of six cases of prostatic cyst and five cases of cysts of the seminal vesicles. All patients were symptomatic. T1- and T2-weighted spin-echo images were obtained in all cases; pathologic confirmation was available in four patients. MR images were analyzed prospectively without knowledge of clinical data or the results of other imaging procedures. In all cases, low- and high-signal masses were observed on T1- and T2-weighted images, respectively. The cysts were unilocular with a sharply defined margin, ranging from 0.5 to 3.0 cm in diameter. The thin wall was of low signal intensity on T2-weighted images. Our experience suggests that MR imaging is useful in demonstrating the liquid content of prostatic and seminal-vesicle cysts and in establishing their size and location.