Secondary signs on static stress MRI in anterior cruciate ligament rupture.

The MRI diagnosis of ACL rupture based on primary signs has variable rates of diagnostic accuracy. These signs observed on direct visualisation of the ACL include discontinuity of fibres, abnormal ligament contour and increased intrasubstance signal intensity. Secondary radiological signs of ACL rupture are increasingly being used. These indirect ancillary signs include PCL angle, translocation of the tibia relative to the femur and displacement of the posterior horns of the menisci. The aim of this study was to investigate if the application of static stress force to the knee will accentuate the secondary signs of ACL rupture on MRI. One hundred and forty-eight subjects (50 subjects with arthroscopically confirmed ACL rupture, 48 subjects with arthroscopically confirmed intact ACL and 50 subjects with clinically confirmed normal knees) underwent MRI of their knee with the application of specially designed fibreglass leg splints which exert a translational force on the knee joint. Five secondary radiological signs were evaluated and all were found to be significantly accentuated following the application of the splints (p<0.001). The MRI diagnosis of ACL rupture demonstrated a sensitivity of 95.9%, specificity of 91.7% and accuracy of 93.8%. The static stress technique improved the accuracy of diagnosing ACL ruptures on MRI and illustrated the abnormal tibiofemoral kinematics.

CT of the musculoskeletal system: what is left is the days of MRI?

Magnetic resonance imaging (MRI) plays a central role in the modern imaging of musculoskeletal disorders, due to its ability to produce multiplanar images and characterise soft tissues accurately. However, computed tomography (CT) still has an important role to play, not merely as an alternative to MRI, but as being the preferred imaging investigation in some situations. This article briefly reviews the history of CT technology, the technical factors involved and a number of current applications, as well as looking at future areas where CT may be employed. The advent of ever-increasing numbers of rows of detectors has opened up more possible uses for CT technology. However, diagnostic images may be obtained from CT systems with four rows of detectors or more, and their ability to produce near isotropic voxels and therefore multiplanar reformats.

MRI of early symptomatic metal-on-metal total hip arthroplasty: a retrospective review of radiological findings in 20 hips.

AIM: To perform a retrospective review of all the conventional radiographic and magnetic resonance imaging (MRI) studies performed in patients with early postoperative pain following cobalt-chrome metal-on-metal total hip arthroplasty. METHODS: A retrospective review of the radiology, surgical findings and histology in nineteen patients who had undergone a total of 20 hip arthroplasties using a cobalt-chromium on cobalt-chromium alloy prosthesis was undertaken. RESULTS: Measures of implant placement on the immediate postoperative radiographs were all within the normal ranges (n=20). Where more than one postoperative radiograph was available statistical analysis revealed no evidence of progressive change before the MRI examination (14). The median postoperative time to MRI was 35 months (range 11-63 months). Abnormalities were demonstrated using MRI in all symptomatic hips (n=20). These comprised: periprosthetic fluid collections (20), which were isointense to muscle on T1-weighted images in 19 cases and hyperintense on T2-weighted images in 18 cases, periprosthetic bone marrow oedema (n=6), muscle oedema (n=4), avulsion of the gluteus minimus and medius tendons (n=5), atrophy of piriformis (n=15) and obturator internus (n=17), and fracture of the medial calcar (n=1). Operative findings in patients who had undergone revision surgery (n=15) included: fluid-filled cavities (n=11), soft tissue necrosis (n=8), gluteal tendon avulsion (n=5), proximal femoral diaphyseal necrosis (n=4), and pitting and corrosion of the femoral stems (n=8), which were, in all cases, firmly fixed to the cement mantle. Histology revealed viable tissue in six hips with necrosis (n=12) and fibrin deposition (n=15) being the predominate findings. Other findings included a perivascular lymphocytic infiltrate (n=5), features of active inflammation (n=4), and metallosis (n=1). CONCLUSION: A significant number of patients with metal-on-metal hip replacements presented with early postoperative pain because of an abnormal soft-tissue reaction. MRI can demonstrate characteristic soft-tissue disease in these patients where conventional radiographs are frequently normal.

CT and MRI of hip arthroplasty.

Plain films are the initial imaging method of choice for evaluation of hip arthroplasty. Recent advances in technology and imaging techniques have largely overcome the problems of beam hardening in computed tomography (CT) and magnetic susceptibility artefact in magnetic resonance imaging (MRI). CT and MRI have now become useful imaging techniques in the assessment of hip arthroplasty.

Regional migratory osteoporosis: a review illustrated by five cases.

Regional migratory osteoporosis is an uncommon self-limiting disease characterized by an arthralgia which migrates between the weight-bearing joints of the lower limb. The radiological features of the disease obtained by conventional radiography, CT, MRI and radionuclide scintigraphy are illustrated by means of five case reports. These range from the most common presentation of sequential, proximal to distal spread in the lower limb to the rare intra-articular form, and disease involving the axial skeleton is also recognized. Clinical and radiographical features often overlap with those of diseases such as transient osteoporosis of the hip and transient bone marrow oedema syndrome, which is reflected in confusing terminology. Histological sampling is usually unnecessary; the radiological features are characteristic and the histological findings are not specific. Regional migratory osteoporosis is associated with systemic osteoporosis. This association is probably under-recognized, and has implications for the pathophysiology of the disease and for treatment.

A swollen leg unmasks longstanding SLE.

We report a case of long-standing SLE which presented with symptomatic muscle vasculitis on a background of photosensitivity, arthralgia and myalgia. The diagnosis was complicated by cardiomyopathy, nephrotic syndrome and diabetes. We highlight the benefits of aggressive treatment in severe disease and the importance of recognising and treating comorbidity especially ih relation to atherosclerosis.

Imaging of the rotator cuff: an arthrographic pitfall.

We present a case where MRI and arthrography of the shoulder reports provided seemingly conflicting data. The subsequent findings at arthroscopy revealed a potential pitfall in arthrographic interpretation.

Vascular intervention in the thorax: bronchial artery embolization for haemoptysis.

Massive haemoptysis is defined as the expectoration of more than 600 mls of blood in 48 h. Many patients are not surgical candidates because of the presence of severe bilateral pulmonary disease and these individuals are best managed by bronchial artery embolization. Occlusion of both the bronchial arteries and hypertrophied non-bronchial systemic arteries is essential if bleeding is to be controlled. A pulmonary arterial source of haemorrhage is uncommon but should always be considered in a patient who has further haemoptyses shortly after a technically successful embolization of bronchial and non-bronchial systemic arteries. The immediate control of haemorrhage is achieved in the majority of patients although subsequent rebleeding on longterm follow-up is not uncommon.

Diffuse pleural thickening: percutaneous CT-guided cutting needle biopsy.

PURPOSE: To assess the diagnostic yield of computed tomography (CT)-guided percutaneous cutting needle biopsy of diffuse pleural thickening. MATERIALS AND METHODS: In 42 consecutive adult patients with diffuse pleural disease seen, 45 CT-guided percutaneous biopsies were performed with an 18-gauge cutting needle powered by a hand-held, spring-operated biopsy instrument. Results were assessed retrospectively. RESULTS: Sufficient pleural tissue for histologic diagnosis was obtained in 42 of the 45 biopsies, with a correct histologic diagnosis made in 39 of the 42 specimens. Specificity and sensitivity for helping differentiate malignant from benign disease were 100% and 83%, respectively. Positive and negative predictive values were 1.0 and 0.60, respectively. By combining findings at biopsy and at CT (presence or absence of pleural thickness greater than 1 cm, mediastinal-circumferential involvement, irregular contour), sensitivity and negative predictive values reached 100% and 1.0, respectively. CONCLUSION: Combined findings of CT-guided percutaneous cutting needle biopsy and CT are useful in first-line investigation of diffuse pleural thickening.

Gamma interferon-mediated cytotoxicity related to murine Chlamydia trachomatis infection.

After infection with the mouse pneumonitis agent (MoPn; murine Chlamydia trachomatis), heterozygous (nu/+) but not nude athymic (nu/nu) mice produced enhanced amounts of gamma interferon (IFN-gamma) in vitro in response to MoPn antigen that exhibited cytotoxic activity when added to host cells already infected with chlamydiae. Antibody-complement lysis showed the cytotoxic activity to be dependent, at least in part, on L3T4+ T cells for production. The cytotoxic responses were directed primarily against Chlamydia-infected target cells, but a second type of toxicity was demonstrable against uninfected target cells after treatment of the generating cell population with anti-Lyt-2 antibody plus complement at certain time points after infection. This additional nonspecific cytotoxic activity was presumably due to a second factor (factor X) acting in concert with IFN-gamma. Lyt-2+ cells, however, also were shown to play a role in IFN-gamma production and cytotoxicity directed against infected targets at later time points after infection. Neutralization of IFN-gamma in the samples containing cytotoxic activity abrogated the cytotoxicity against both infected and uninfected targets, but cloned murine IFN-gamma exhibited toxicity in a dose-dependent manner only against infected target cells. The data provides evidence that cytotoxicity against infected targets is due to antigen-specific induction of IFN-gamma, but other cytokine activity, most demonstrable after removal of Lyt-2.2+ cells and cytotoxic to uninfected targets, also is present.