Imaging Essentials

Day 2 again began with a general opening session on imaging including presentations on: Imaging the spine in the presence of metalwork ; Muscle grading – BA vs UEFA; Imaging the pelvis. Groin or hip?; MRI sequences; 1.5 vs 3T imaging; USS vs MRI; Metal artefact reduction sequences; Mitchell and Lee's miscellany; When to image acute injury; When to use gadolinium; Drugs and complications; Hunt the fragment: meniscus and cartilage; and When should I refer to a tumour centre?

This session was a whistle-stop tour of clinical questions that radiologists are often asked about imaging, involving thirteen 7-minute bite-size presentations. The role of the radiologist can be crucial in aiding a good diagnosis, particularly in grading severity. However, it is important not to stop looking once the obvious lesion has been seen but to also look for other injuries and pathology outside the area of interest. Imaging the spine in the presence of metalwork is most commonly done post-surgery. Routine post-operative imaging involves plain-film at 6 weeks and at 1 year. Imaging for post-operative complications can be done using CT to check the metalwork or MRI (soft-tissue or collection/infection). Pseudoarthrosis at 1+ year can be checked by plain film, CT or single-photon emission computed tomography (SPECT), and adjacent level degenerative changes can be seen by plain films and MRI. MRI grading of muscle injuries is useful to confirm injury diagnosis and severity. Grading systems have been developed which may assist in estimating time to return to play. Within the UK, there are two systems in common use: the grade 1-3 UEFA system (familiar to the player, agent, manager and medical team) and the grade 0-4, a-c BAMIC system (familiar to medical team mainly). Discussion with the referring physician which system he prefers and use both in equivocal cases.

Imaging the groin is useful for seeing spurring, irregularity, disc extrusion, inguinal canal, as well as the severity of bone marrow oedema and adductor/capsule/cleft oedema. 3T imaging of the hip allows the best assessment of the labrum and cartilage even compared to 1.5T MRA. A number of MRI sequences are available and the European Society of Musculoskeletal Radiography produced list of ideal scanning sequences for a sporting problem, usually variation on this ideal is done. Advantages of T1-weighted, proton-density, fat-saturated sequences as well as short tau inversion recovery (STIR) were discussed, as were the benefits/disadvantages of 1.5 versus 3T. Ultrasound (US) and MRI are complimentary tools for assessing MSK pathologies: US has some clear advantages (e.g. in dynamic pathologies and for guided interventions) and MRI can be the better test for assessing internal derangement of large joints and bone marrow/cartilage pathology. Imaging acute injury is useful in muscle injury (MRI and US) and fracture. Gadolinium (Gd)-based contrast reagents have to be used with caution. However, intra-articular Gd in MRI arthrograms is useful for imaging hip, shoulder, elbow, foot and wrist joints, and intravenous Gd enhances visualisation of synovitis, and tumour and post-spinal surgery assessment. The use of a variety of drugs (including radiation, local anaesthetics, steroids, prolotherapy, Gd, and drugs in pregnancy and breast feeding) and their complications were discussed. In looking for meniscal and cartilage fragments it is important to understand the joint anatomy, recognise that osteochondral bodies can grow in chronic situation, and to keep looking. Beware of the pitfalls of meniscal ligaments and horizontal flap tears. When imaging sporting injuries, the radiologist needs to be aware of a range of findings that might or might not be clinically relevant to the injury. If a neoplastic lesion is found the patient always needs to be referred to a tumour centre.