Ultrasound is a non-invasive solution to examining tissues in real-time. We were recently mentioned in a press release regarding musculoskeletal ultrasonography, which happens to be one of our specialities. View the press release here https://www.infonews.co.nz/news.cfm?id=115380 or read it below.
Ultrasound is a well-established and effective modality in musculoskeletal (MSK) imaging – its role in diagnostic imaging continues to expand with the advancement of ultrasound technology, allowing us to see finer details in joints and muscles. Together with X-ray Imaging, Ultrasonography is considered as first line modality in investigation of musculoskeletal pathology. It is gaining popularity among the orthopaedic surgeons, sport medicine specialists, rheumatologists, general practitioners and physiotherapists, who used to refer their patients to CT and MRI only.
Clinical evidence and research supports using ultrasound as a primary diagnostic test for numerous musculoskeletal conditions as it offers a number of important advantages compared to CT and MRI in terms of safety and effectiveness. Diagnostic ultrasound is non-invasive and offers real-time imaging, allowing the possibility to examine the structures at rest and in motion. This ability to capture the movement of musculoskeletal components differentiates it from other imaging modalities and permits more accurate diagnosis. Other advantages for the patients include its portability and low cost.
The first report of musculoskeletal ultrasonography was published in 1958 by K.T. Dussik, who examined the articular and periarticular tissues, including tendons, ligaments, muscles and synovium to establish the effects of different pathological processes in joint tissues on ultrasound attenuation, i.e. how these tissues appear on the scan when in normal condition versus when the pathology is present.
The first ultrasound image of a human joint was published in 1972 by Daniel G. McDonald and George R. Leopold in the British Journal of Radiology. They described the use of ultrasound imaging in differentiating Baker’s cysts from thrombophlebitis, a common application in the current clinical practice. The demonstration of the ultrasound features of the congenital hip dislocation by R. Graf led to the first widespread practical application of ultrasound in musculoskeletal disease.
At present, the diagnosis of congenital hip dysplasia (CHD) and further management of this condition is based mainly on ultrasound scans, replacing the X-ray. When we compare the ultrasound images taken in the 1980’s-1990’s, with the high-resolution images obtained with modern machines, we can clearly see an amazing difference between the old and new equipment: a snowstorm vs. a clear image with fine definition of the small details, measuring less than a millimetre. The last-generation broadband probe (8–16 MHz) clearly shows loss of cartilage on the metacarpal head, bone erosion, synovial proliferation and fluid collection in patients with metacarpophalangeal joint arthritis, providing valuable information about the joint condition.
The first application of power Doppler demonstrating a soft tissue hyperaemia in musculoskeletal disease was reported in 1994 by J. S. Newman. The first use of ultrasound to guide a joint aspiration and diagnosing a case of septic arthritis was reported in 1981 by B. M. Gompels. Advanced technologies such as power Doppler, ultrasound contrast agents and elastography have more potential to revolutionize the ability of ultrasound to detect joint inflammation, firmly establishing the musculoskeletal ultrasound as a routine tool in clinical rheumatology.
Musculoskeletal ultrasound is the first line of investigation in sports medicine and can provide a quick answer for such questions as ‘is there a tear?’, ‘is it a sprain?’, ‘what is the best management – rest and physiotherapy, or a surgical consultation?’ A great advantage of ultrasound is the absence of ionizing radiation. It is particularly important for children and in pregnancy. While X-rays are useful for bone and joint surface conditions, MRI and Musculoskeletal Ultrasound are used for evaluation of the soft tissues, such as muscles, ligaments and tendons.
MRI is a great modality because it does not involve ionizing radiation, while providing lots of detail in the soft tissues, muscles, tendons, and cartilage. Nevertheless, patients with pacemakers, various ferromagnetic implants or prosthetics and previous exposure to metal works may not be able to undergo the MRI examination, as the machine creates a very strong magnetic field. At the same time, the Musculoskeletal Ultrasound is safe and can be performed on anyone. There is no radiation, no magnets and it is commonly done on pregnant women, which demonstrates that there are no contraindications for this modality. Claustrophobic patients who cannot go into the MRI tunnel can be examined with ultrasound.
There have been clinical cases where the surgically implanted hardware was rubbing against a muscle or tendon, creating extreme pain and constant irritation to the structure. Only with the Musculoskeletal Ultrasound this type of complication can be diagnosed. Musculoskeletal ultrasound allows for dynamic evaluation, which can improve the radiological interpretation of the clinical relevance of findings seen in static images (e.g. shoulder impingement).
Sometimes a patient can only feel the pain with movement, so performing a dynamic stress-test during the ultrasound scan can easily diagnose the abnormality.
Standard high-frequency ultrasound probes also resolve finer imaging detail, compared to many types of clinical musculoskeletal MRI’s. The axial resolution of a 10 MHz probe is 150 um. A 1.5T MRI scanner with a field of view of 12 x 6 cm and a matrix of 256 x 256 pixels, with a slice thickness of 0.5 cm has a resolution of 469 x 469 um. Another benefit of the ultrasound is the real-time Doppler imaging, which can point us in the right direction towards more accurate diagnosis. Increased vascularity in the synovial tissue, tendon or bursa indicates inflammation and acts as an “arrow”, helping to diagnose arthritis, tendinopathy or bursitis.
Musculoskeletal Ultrasound greatly helps with injection procedures, guiding a specialist to a specific structure of interest (bursa, tendon, joint space). It significantly improves the accuracy of the injection, thereby directly increasing the effectiveness of the procedure overall. With ultrasound we can compare bilateral structures. Comparing possible pathology on both sides is helpful in determining if the pathology is in fact, the pain generator. For example, thickening of a tendon can occasionally be seen on both sides of the body regardless if symptomatic or not.
On the MRI, we are only able to view one side per imaging study, which could lead an inaccurate diagnosis or cause increased costs for the patient for follow up imaging.
Long structures like nerves and muscles can be viewed in their entirety in one test, and it is a great advantage over the MRI. An MRI scan can only show a section of the body or part of the limb. Musculoskeletal Ultrasound is a dynamic study that allows us to follow a structure all the way from its origin to its attachment. Neurological symptoms, like numbness in the fingers, can be a result of compression or swelling around the nerve anywhere along its course down to the limb. In the same way, we can evaluate the long muscles, such as hamstring.
Ultrasound examination is less expensive to conduct than a CT or an MRI. Ultrasound is, however, operator dependent and requires a detailed knowledge of the relevant anatomy and ultrasound artifacts (e.g. tendon anisotropy). MSK training in ultrasound requires extra time and the sonographer must know the protocol and understand the complex ultrasound appearances of both normal and abnormal structures in order to be able to interpret the findings in real time.
Eastmed Radiology specialises in musculoskeletal imaging and offers a comprehensive range of MSK examinations with state-of-the-art equipment. Contact us on (09) 585 0534 or book online at www.eastmedradiology.co.nz