Lecture_W5_Diagnostic imaging for musculoskeletal system.pdf

Introduction to diagnostic imaging and interpreting radiology Dr Brooke Coombes Acknowledgment Dr Dilani Mendis Learning Outcomes • Describe common diagnostic imaging techniques for the musculoskeletal system • Discuss the advantages, disadvantages and specific safety precautions of each modali...

Introduction to diagnostic imaging and interpreting radiology Dr Brooke Coombes Acknowledgment Dr Dilani Mendis Learning Outcomes • Describe common diagnostic imaging techniques for the musculoskeletal system • Discuss the advantages, disadvantages and specific safety precautions of each modality • Describe the systematic approach to reading and interpreting an x-ray • Define terminology used to report findings on x-rays • Relate x-ray findings to the aetiology, mechanism of injury and clinical decisions As a physiotherapist, you will need to: • Understand which imaging modalities are appropriate for investigating MSK conditions • Interpret imaging results together with clinical findings • Explain imaging results to your patient or colleagues Common Imaging Modalities • Radiography (X-rays) • CT • MRI • US Plain Radiography (McKinnis 2014) Plain Radiography • X-rays absorbed depending on tissue density • Metal Metal • Bone • Soft tissue (water) • Fat • Air/Gas • Plain films are two-dimensional (i.e. give no sense of depth) à often need at least 2 views to identify Bone Soft tissue (M) Soft tissue (F) Air Two-dimensionality… AP Two-dimensionality… AP Lat Plain Radiography Pros • Low cost • Minimally invasive • Useful for assessing bony abnormalities eg. fractures, subluxation, calcified tissue Plain Radiography Pros Cons • Low cost • Does not image soft tissue • Minimally invasive • Useful for assessing bony abnormalities eg. fractures, subluxation, calcified tissue well • Does not image behind bone • Uses ionizing radiation Computed Tomography (CT) • Based on same imaging principles as conventional radiography • Uses X-rays that are attenuated by body tissues • Creates images based on cross-sectional (axial) slices (McKinnis 2014) CT Pros • Quick • Good for Ax of bone & soft tissue eg. Trauma, tumours • Useful for bone & cartilage delineation eg. Subtle & complex #, degenerative changes, spinal stenosis, bone mineral analysis • 3D representation CT Pros Cons: • Quick • High radiation dose • Good for Ax of bone & soft tissue • Higher cost than plain X- eg. Trauma, tumours • Useful for bone & cartilage delineation eg. Subtle & complex #, degenerative changes, spinal stenosis, bone mineral analysis • 3D representation ray (but cheaper than MRI) • Not great for soft tissue differentiation if similar radiodensity Magnetic Resonance Imaging (MRI) • Uses a magnetic field and radiofrequency signals to cause protons to line up in the direction of the magnetic field • As protons re-align they release energy • This induces a current in a receiver coil which is converted to images by a computer • Produces gray-scale images of tissues represented as slices Magnetic Resonance Imaging (MRI) • Most MRI sequences refer to the shade of grey as “intensity” • High = white • Intermediate = grey • Low =black Magnetic Resonance Imaging (MRI) • T1 vs T2 images • The timing of RF pulse sequences highlight different tissues • T1 images – highlight fat • T2 – highlight fat and water MRI Pros • Non-invasive • No ionizing radiation • Excellent soft tissue differentiation eg. Partial vs complete tears of tendon or ligament • Sensitive to detecting changes & variations in bone marrow eg. Bone tumours, stress fractures • 3D representation MRI Pros Cons • Non-invasive • Length of time taken to • No ionizing radiation • Excellent soft tissue differentiation eg. Partial vs complete tears of tendon or ligament • Sensitive to detecting changes & variations in bone marrow eg. Bone tumours, stress fractures • 3D representation produce an image • High cost • Contra-indications: metal implants, pacemakers, claustrophobia MRI – Research Applications Ultrasound (US) • Uses sound waves reflected off tissue interfaces to produce pictures of muscles, tendons, ligaments, nerves and joints • Useful for diagnosis of MSK injuries • Can be performed in real time – dynamically move different structures Ultrasound (US) • B- mode = grey scale • Dense tissue reflect more sound waves and appear bright white, • Fluid=black https://radiopaedia.org/cases/microtenotomy-and-prolotherapy-patella-tendon?lang=us Ultrasound (US) • Doppler= measure flow of blood or presence of neovessels • Red (flow toward probe) • Blue (away from probe) https://radiopaedia.org/cases/microtenotomy-and-prolotherapy-patella-tendon?lang=us US Pros • Low cost & portable • Safe - no known hazards & noninvasive • High resolution • Useful for imaging muscles, tendons, ligaments & nerves • Real-time imaging US Pros Cons • Low cost & portable • Limited field of view • Safe - no known hazards & noninvasive • Operator-dependent • Does not penetrate bone • High resolution • Useful for imaging muscles, tendons, • Difficult to image obese ligaments & nerves patients • Real-time imaging Real time ultrasound (RUSI) • Physiotherapists mainly use US as a form of biofeedback known as real-time US imaging • https://www.youtube.com/watch?v =5kTFOpfKqYg https://corephysio.com.au/real-time-ultrasound/ US – Research applications • Muscle architecture, size & function • Fine wire insertion US – Research applications • Muscle and tendon size & stiffness (ultrasound shear wave elastography When is imaging needed? • If the results of imaging would change the course of treatment or understand the prognosis When is imaging needed? • If the diagnosis is unclear • Imaging to rule out a condition is just as informative as confirming a condition is present 13 year old boy presented with intermittent and progressive knee pain over 18 months, no history of trauma or other joint abnormality. Dx osteosarcoma of femur https://pubs.rsna.org/doi/10.1148/rg.281075015 Considerations • Ottawa rules are a set of guidelines for clinicians to help decide if x-rays are indicated to diagnose a possible fracture • Eg. Ankle x-ray only required if • Pain in malleolar zone and any one of: • Bone tenderness posterior tibia or tip medial malleolus • Bone tenderness posterior fibular or tip lateral malleolus • Inability to bear weight immediately and in emergency dept for 4 steps Considerations • How discriminatory is the diagnostic imaging test? • Sensitivity (did the test accurately identify pathology when it is really present?) • Specificity (did the test accurately obtain a negative finding when the condition is really absent?) Considerations • Are the findings relevant to the patient’s problem? • Guidelines recommend against routine use of X-ray, MRI or CT for acute non-specific LBP in absence of red flags Considerations What are the risks? • Cost • Risks of radiation • Incidental findings • Anxiety, fear • Interventions What are the risks of the test? How soon should I have the test? What are the costs of the test? Case 1 • You are the sports physiotherapist for an elite hockey team, providing game day coverage. One of your players sustained an inversion injury and has severe ankle pain. He is unable to weight bear on the leg. • What is your differential diagnosis? • What is the most appropriate (first) imaging test to use and why? Case 1 • Inversion injury • https://radiopaedia.org/cases/bimalleolar-ankle-fracture-1?lang=gb Case 1 Case 1 Findings: • Unstable Weber B fracture of the right distal fibular and fracture of the medial malleolus (bimalleolar ankle fracture). Associated soft tissue swelling. Case 2 • You are the sports physiotherapist for an elite hockey team. One of your players is complaining of knee instability and swelling. He has had multiple prior injuries. • What is your differential diagnosis? • What is the most appropriate imaging test to use and why? Case 2 • Multiple prior injuries, right-sided knee pain. ?ACL rupture • https://radiopaedia.org/cases/osteochondral-knee-injury-and-aclrupture?lang=gb Case 2 Case 2 Case 2 Findings •about 20 mm fragmented osteochondral injury of the medial femoral condylar surface; the fragments are only minimally displaced though there is considerable fluid seeping in between them putting the injury between stage III and IV •more discrete chondral delamination injury of the medial tibial condyle with subchondral oedema •discontinuity of the anterior cruciate ligament (ACL) with a shallow angle •moderate knee joint effusion and synovial proliferation Case Discussion Extensive, likely subacute/chronic osteochondral injury and status post anterior cruciate ligament (ACL) rupture with resultant joint effusion. Case 3 • You are the sports physiotherapist for an elite hockey team. One of the junior (13yo) athletes presents with heel pain which is not settling. • What is your differential diagnosis? • What is the most appropriate imaging test to use and why? Case 3 • Heel pain in an elite junior sportsperson • https://radiopaedia.org/cases/163572/play?lang=gb Case 3 Case 3 Normal Achilles tendon. Retrocalcaneal bursal thickening and hyperaemia with trace fluid. Case 3 Case 3 Findings: Mild bony prominence at the posterosuperior calcaneus (Haglund deformity) with cortical thickening and lucency, probably early enthesopathy. Retrocalcaneal bursitis is an uncommon cause of posterior ankle or heel pain. The small Haglund deformity in this case is a contributing factor, along with the presumed workload of being an elite junior sportsperson. Case 4 • Your patient is a 40 year old male who presents with low back pain, right sided leg pain and pins and needles on his lateral foot. They have had a previous history of recurrent low back pain and he is claustrophobic. You suspect spinal stenosis with nerve root impingement (radiculopathy) as the cause of his symptoms. • What is the most appropriate imaging test to use and why? Case 4 • https://radiopaedia.org/cases/disc-protrusion-with-spinal-canalstenosis?lang=gb Case 4 Case 4 Findings: • There is a large posterocentral and right paracentral disc protrusion at the level of L4/L5, which is causing moderate to severe central canal stenosis. It is also effacing the lateral recess bilaterally, right worse than left, with potential for irritation of the descending L5 nerve roots. No significant neural foraminal stenosis is identified. • There is a smaller broad-based left paracentral disc protrusion at L5/S1 causing mild central stenosis. Case Discussion • Disc protrusions can cause varying degrees of narrowing of the spinal canal or neural foramina. If large enough, they can cause significant neurological symptoms by compressing the cord, cauda equina nerve roots, or transiting nerves in the lateral recess, in which case, orthopaedic spine consultation would be recommended. Reading and interpreting x-rays As a physiotherapist, you will need to: • Be able to recognize x-ray features of traumatic injuries and other rheumatological conditions • Explain imaging results to your patient or colleagues • You may refer for x-rays as a primary contact practitioner • You will need to know what views to request Interpreting the image… • Consistent use of an organized search pattern • Know your anatomy • Know pathology of disease & its presentation • Interpret/report on what you observe and avoid making diagnoses before completing a full Ax • Dx is made in consideration of all clinical findings not just from imaging STOP!!! Check… • • Patient name DOB • Date of investigation • • Latest? • • Serial images Pre/post Sx… Quality of image • • GC Imaging, Southport SMITH, John DOB: 03-01-1965 Date: 20-02-2009 Views, positioning, exposure… Check radiologist’s report has same details! 57 “ABCs” of musculoskeletal films A = Alignment B = Bone appearance C = Cartilage s = Soft tissue 58 Alignment 1. General skeletal architecture 2. Bone contours 3. Positional relationships of bones relative to adjacent bones • Usually reveals: • Fractures • Dislocations • Bone spurs (osteophytes) • Developmental abnormalities 59 Alignment - General • Number, size and location of bones • Presence of epiphyses • Gross deformity 60 Alignment - Contours • Smooth, continuous cortical lines • Continuity at articulations • Bone erosions or outgrowths (osteophytes) 61 Alignment – Positional relationships (McKinnis 2014) 62 Bone appearance • • Is there a normal trabecular architecture? Is there sclerosis at areas of stress (e.g. WB locations, tendon/ligament attachments) • Reveals: • Bone density changes • • Necrotic/lytic areas Chronic/degenerative changes • Tumours • Foreign bodies…etc 63 Bone appearance 64 Cartilage • Joint space • Subchondral bone • Epiphyseal lines/plates • • Cf. other side Reveals: • Degenerative joints • Osteochondral lesions • Erosions • Mechanical interference (McKinnis 2014) 65 Cartilage 66 Soft tissue • • Consider: • Muscles • Fat pads/lines • Joint capsules • Periosteum • Foreign bodies in soft tissue areas Reveals: • Swelling/bleeding • Wasting/atrophy • Joint effusions • Can indicate need for further investigation, occult #, inflammatory process… (McKinnis 2014) 67 Soft tissue (McKinnis 2014) 68 Soft tissue https://www.cmcedmasters.com/ortho-blog/the-adult-knee 69 Soft tissue https://www.cmcedmasters.com/ortho-blog/the-adult-knee 70 Descriptive terms • Location of bone abnormality • Neck / Head / Shaft / Base • Proximal/distal • Diaphysis (shaft) / Epiphysis (end) / Physis (growth plate) / Apophysis (outgrowth of bone where tendons/ligs attach) • Intra-articular / Extra-articular Descriptive terms • Differences in density allow for differentiation on x-rays Radiolucent Radiopaque veteriankey.com/radiographic-quality/ Descriptive terms - Radiolucent or radiopaque? 2 views are better than 1 • For traumatic injuries, at least 2 views are required • For rheumatological conditions e.g. RA this may not be needed • > 2 images for suspected scaphoid fracture 2 views are better than 1 www.radiologymasterclass.co.uk Compare to the other side www.radiologymasterclass.co.uk Look for the unexpected www.radiologymasterclass.co.uk Image quality • Acquisition of images requires careful patient positioning • Affected by pain or co-operation • May request new images if suboptimal • Does it show joint above and below? • Is it free of artifacts? Tutorials in weeks 6-8 • You will develop skills in reading and interpreting radiology • How to prepare: • Complete online tutorials (external resources) • Answer independent learning activities (questions relate to above) • Attend face to face tutorials to put skills into practice QUESTIONS?