Article

Using MRI To Diagnose Swelling Or Bleeding Of The Knee

The knee is one of the most frequently injured appendages of the body for two reasons — it acts as a weight-bearer, and this joint does not display stability obtained by congruity of the hip and ankle.1

To address problems such as the acutely swollen knee, a common presentation for knee pathology, a complete examination needs to be performed in order to make a proper diagnosis, following which the right treatment plan can be determined. Often considered one of the easiest and non-invasive diagnostic techniques is magnetic resonance imaging, commonly known as MRI.1

An MR scan of the knee will be able to provide, from different angles, details of the structures within the joint such as bones, tendons, ligaments, blood vessels, etc. MRI systems utilize a powerful magnetic field and radio frequency pulses instead of invasive ionizing radiation to produce comprehensive images of internal body parts, which can be viewed on a computer screen.2

Therefore, MRI, along with conventional tools like CT or X-rays, can help diagnose and evaluate conditions of the knee. Possible conditions include knee pain and swelling, bleeding in the tissues around the joint, fractures, tumors, both primary and metastatic, pain or trauma and complications of the knee.2

Diagnosis by MRI for the Knee

A review published in the Knee Surgery, Sports Traumatology, Arthroscopy journal, compared the diagnostic accuracy of MRI in patients with possible meniscal tears of the knee and ACL (anterior cruciate ligament) injuries. Results showed sensitivity and accuracy of MR scans.3

In some situations, doctors may also prescribe knee arthroscopy with an MRI, a surgical method performed to detect abnormalities and treat the knee joint. During this process an MR arthrogram (seen with the help of contrast-enhancing agents) can indicate the etiology of the knee and its structures. As described by a research study, MR arthrography is generally employed for two indications; the estimation of meniscus tears in the knee after surgery, and to track lesions or tumors in the bones of the knees.2,4

Explaining further, in a study authored by Gupte, C. and St Mart, P., patients above the ages of 65 typically manifest patellofemoral (known as “runners knee”) degenerative changes or meniscal tears. These symptoms can be detected by way of measuring clinical tenderness. In addition, to accurately determine the cause of suspected knee injuries, MRIs along with basic radiographs can be advised in these scenarios. In patients aged less than 60, MR pictures can detect ligament tears, lumps or recurrent anterior knee pain.1

Research has also shown that MRI plays a critical role in imaging lesions of the knee. After a careful initial evaluation of the anatomical structure, and assessment of the patient's clinical background, an MRI may be required to further appraise the injury. In some patients the synovial membrane, which is the tissue that lines joints such as the knee, can be prone to the origination of tumors and tumor-like lesions. A 2016-research paper has called MRI “the best and ideal method” to provide more information on the extent of these lesions of the knee. The imaging technique also proved useful in differentiating cysts from other masses observed in the joint area.9

Professor Philip Conaghan of the University of Leeds and President of the International Society for Musculoskeletal Imaging in Rheumatology, said, “MRI reveal[s] inflammation, which we could not see directly before and had to rely on blood tests and using our fingers to feel the joints.”10

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MRI Comparison Studies 

The rapid evolution of technology, in terms of hardware and software, in other diagnostic tools also brought about the introduction of the 3.0 T (Tesla) MRI scanners. Even though many hospitals and healthcare settings still maintain their 1.5T machines, it has been indicated that the 3.0T scanners exhibit improved image quality, owing to the higher magnetic field involved and an enhanced signal-to-noise ratio. MRI equipment for the knee is also gradually shifting towards the higher-Tesla devices.5

As for diagnostic ability, a research paper by Van Dyck et al. compared the two types of MRI scanners on 200 volunteers with prospective ACL tears and to assess meniscal pathology of the knee. Half of this number underwent knee arthroscopy, and the sensitivity and specificity between the 1.5 T and 3.0 T were calculated. From these results, the investigators found that the 3.0T MRI protocol did not significantly show more accuracy for knee menisci and ACL compared to its predecessor.5

Recently, there has also been talk of musculoskeletal ultrasound (US) as a replacement for MRI in terms of diagnosing and monitoring  Morel-Lavallée lesion (MLL).6 This condition is rare but important; it is typically caused by a post-traumatic pain at the knee.7 A paper published in the PM&R journal performed ultrasound and an MRI, as a diagnostic test and follow-up procedure on a patient with MLL. The results showed that both procedures were able to identify different key aspects of the lesion at the knee.6 Another publication corroborated similar observations where both ultrasound and MR imaging were helpful in the diagnosis of MLL.7

Conclusion 

There is a continual emergence of new technologies around us, yet it can be said that the role of imaging modalities like MRI will still be an integral part of detecting and diagnosing health and disease in the body. 

 

 

References:

(1) Gupte, C. and St Mart, J. (2013), ‘The acute swollen knee: diagnosis and management’, JRSM, 106 (7), Pp 259-268

(2) Magnetic Resonance Imaging (MRI) - Knee, 2018, Radiologyinfo.org, https://www.radiologyinfo.org/en/info.cfm?pg=kneemr, (accessed 22 Aug 2018)

(3) Phelan, N. et al. (2016), ‘A systematic review and meta-analysis of the diagnostic accuracy of MRI for suspected ACL and meniscal tears of the knee’, Knee Surgery, Sports Traumatology, Arthroscopy, 24 (5), Pp 1525-1539

(4) Chung, C. et al. (2005), ‘MR Arthrography of the Knee: How, Why, When’, Radiol Clin N Am, 43, Pp 733-746

(5) Van Dyck, P. et al. (2013), ‘Prospective Comparison of 1.5 and 3.0-T MRI for Evaluating the Knee Menisci and ACL’, The Journal of Bone & Joint Surgery, 95 (10), Pp 916-924

(6) Goodman, B. S. et al. (2013), ‘A Comparison of Ultrasound and Magnetic Resonance Imaging Findings of a Morel-Lavallée Lesion of the Knee’, PM&R, 5 (1), Pp 70-73

(7) van Gennip, S. et al. (2012), ‘Pain at the knee: the Morel-Lavallée lesion, a case series’, Clin J Sport Med, 22 (2), Pp 163-166

(8) Phan C. M. et al. (2006), ‘MR imaging findings in the follow-up of patients with different stages of knee osteoarthritis and the correlation with clinical symptoms’, Eur Radiol, 16, Pp 608-618

(9) Larbi, A. et al. (2016), ‘Imaging of tumors and tumor-like lesions of the knee’, Diagnostic and Interventional Imaging, 97 (7-8), Pp 767-777 

(10) The Use of Imaging Scans in the Detection and Monitoring of RA, 2018, Arthritis Foundation - Rheumatoid Arthritis blog, http://blog.arthritis.org/rheumatoid-arthritis/detecting-rheumatoid-arthritis/, (accessed 23 Aug 2018)