Anatomy in MRI Magnetic Resonance Imaging - Report Example

Anatomy of Magnetic Resonance Imaging Anatomy in Magnetic Resonance Imaging Introduction to elbow joint- Elbow joint is a synovial joint which is also commonly known as Hinge joint. Elbow joint allows variety of movements such as pronation of the forearm, supination, flexion and extension of the joint. Elbow joint is formed by the articulation of Humerus, Radius and Ulna attached with some soft tissues and Co-lateral ligaments. Radio-Humeral articulation helps pronation and supination of the forearm while flexion and extension at elbow is due to Ulna-Humeral articulation. Anatomy of elbow joint- Bones- Head of Radius and Ulna articulate with Humerus capitellum and trochlea. Proximal end of the radius and Ulna also articulate with each other at the sigmoid notch. (Trovinger, Sonin, Otte, N.p, p11) Left elbow joint with posterior and radial collateral ligament. Curtsey – Anatomy of Human Body by Gray.H Muscles and cartilages- Muscles involved on the anterior side of the elbow joint are Biceps brachii, Brachialis, Pronator terrace and Brachioradalis. On the medial side there are Pronator terrace and superior flexor muscles connecting wrist with medial epicondyle of the Humerus. On the lateral side, there are Brachioradalis, Supinators and extensor carpi radialis longus and extensor muscles of wrist. Posterior part of the elbow is covered with triceps and anconeus muscles. Elbow joint is supported sideways by radial collateral ligament and ulnar collateral ligament and several articulating cartilages. (Trovinger, Sonin, Otte, N.p, p11) Elbow Joint lateral view-Courtesy- Medical pictures info (2011) Neurovascular supply- Elbow joint is supplied with brachial artery and ulnar, median and radial nerves. Brachial artery is superficial in the cubital fossa lying over Brachialis. It gives out branches as ulnar and radial arteries. Median nerve gives out many branches supplying anterior muscles of forearm (Bianchi, S. Martinoli (N.p) pp 1-10) Two possible ways of patient positioning for MRI of the elbow -Comparison For MRI reading of elbow injuries, various hand positions are used. These positions and selection of coils are depending upon some factors. Those factors are Physical restriction for the patient or disability Patents’ age and body size Limitation of current MRI machines Here are few possible positions listed below, Arm overhead position- Patient is in prone position with the injured hand over the head. This puts arm straight into magnetic Isocenter for better homogenic field response. This is a comfortable position for the patients who are afraid of low light conditions. Disadvantage of this position is that pronation of the hand causes discomfort and restlessness to many patients. This causes unexpected hand movements resulting in image errors. (Anderson,2011) Arm by side position- Patient is lying in supine position with the affected hand sideways. This is convenient position to maximum patients, so there are less motion errors. But disadvantage of it is that, elbow is put in the area of low homogenic field which affects image quality .(Anderson,2011) Common artefacts encountered during elbow MRI- Imaging technology is getting advanced with the time. It is helping to reduce common artefacts that come across during MRI elbow procedures. During MRI elbow, routinely seen artefacts are as follows, Chemical shift artefact- This is a major artefact and mostly observed during “high field strengths” and which is overcome by adjusting “receiver bandwidth”. (Anderson,2011,pp 5-6) Susceptibility artefact-This is also very important artefact. It is seen in “high field strengths”, in case of “metallic implants” and also in “gradient-recalled pulse sequence”. To control this artefact, voxel size is reduced while image matrix is increased. And slice thickness is also reduced along with FOV to minimise susceptibility artefact. (Anderson,2011,pp 5-6) Rotator Cuff- Rotator cuff is protective structure of the shoulder joint. It provides support and strength to the joint. Cuff is made up of muscles and tendons such as Supraspinatous, Infraspinatous, and Subscapularis and Teres minor and joint capsule. (Steinbach, Gunther (2000), pp 214) and (Merriam Webster, n.p.) Rotator Cuff Anterior and Posterior view respectively. Curtsey: American Family Physician, 1998 Calcified Tendonitis- Calcified Tendonitis is commonly seen in elderly patients and females. In Calcified Tendinitis, there is deposition of hydroxyapatite crystals inside the tendon of rotator cuff. These calcified crystals are commonly found in Supraspinatous tendon of shoulder joint but also found in Infraspinatous and Subscapularis tendons. (Serafini, Sconfienza, Lacelli, 2009) and (Steinbach, Gunther (2000), pp 214) Development of Calcified Tendonitis- The important causative factor of Calcified tendonitis is reduction in oxygen tension in the tendon causing abnormal growth in cartilaginous tissue. This gets changed into calcified structure. (Serafini, Sconfienza, Lacelli, 2009) Clinical Presentation- Development of calcified tendonitis occurs through four steps. They are, 1. Pre-calcific 2. Calcific 3. Resorptive 4. Postcalcific. (Serafini, Sconfienza, Lacelli, 2009, n.pp) During first two stages of calcified tendonitis patient complains of constant dull pain over the long period. Pain is more during nights. As the condition worsens, patient starts getting sudden pains .These pains are very severe and also sometimes shifting towards neck region or downward along the arm. Patient may also have restriction of movements, weakness and increase intratendinous pressure. (NHS, 2011) and (Serafini, Sconfienza, Lacelli, 2009) X ray Finding- Radiographic examination is a must in such cases. X- Ray shows calcified crystals clearly. Preferred positions for x ray examination are AP view of the shoulder with internal rotation and external rotation where calcified structures are clearly observed. (Steinbach, Gunther (2000), pp 214) MRI findings- MRI is not useful unless the crystals are enough large in size and surrounded by high density oedematous fluid. This fluid is noticeable on T2 weighted images. Oedema is also seen in cases of rotator cuff tear so it is important to compare MRI study with previous x rays to confirm the diagnosis. (Steinbach, Gunther (2000), pp 214) Brief introduction to Carpel Bones or wrist bones- Carpal bones are eight in number and are arranged in two horizontal rows. Proximal row articulates with Ulna and Radius and distal row articulates with metacarpal bones of the hand. They are named as Trapezium, Trapezoid, Capitate, Hamate, Triquetrum, Scaphoid, Pisiform, and Lunate. Left hand carpal bones Curtsey- Anatomy of human body. Gray. H Ganglion Ganglion is a palpable cyst. It contains thin, light coloured mucus like structure. Ganglion is formed either from a tendon or capsular joint. Ganglion can be found at various locations over the wrist but most commonly dorsum side of the wrist. They are usually painless and disappear over the time. (Teh, J. Whitley G., 2005, p 1-2) Ganglion Curtsey- .American Society for Surgery of Hand, 2007 Causative factor Exact causative factors are not known. It is found more in young females and athletes because of the excess stress on the wrist. (American Society for Surgery of Hand, 2007) MRI finding- Ganglion appears similar to synovial cyst. It is difficult differentiate on histopathology tests. So MRI is advised for confirmation. On MRI, Ganglion appears as a unilocular or multilocaular mass, round in shape and usually located near wrist joint or tendoneous sheath. Diagnosis of ganglia has been made by observing small quantity of fluid with the fluid from joint cavity. On T1 weighted images ganglion appears low signal but at times cyst contain haemorrhagic or proteinaecous fluid which is seen either is intense or hyper intense on the film. . (American Society for Surgery of Hand, 2007) Carpal tunnel syndrome Carpel tunnel is a space in wrist joint. Median nerve and some tendons and artery pass through it. Any pressure over this region or repetitive movements of the wrist causes Median Nerve compression and Carpel Tunnel Syndrome. E.g. some swelling of the tendon inducing pressure over the nerve. It could be present on both the hands in 50% of cases and commonly found in female patients. (TJFP, 2003) and (Steinbach, Smith, D. (2000) pp.313-314). Clinical Picture Carpel Tunnel syndrome will have symptoms such as tingling numbness, weakness of hand and burning sensation. Patient also complains of pain and pressure in the hand which extends upwards and also loss of sensation. Complaints are usually more at night making patient restless. (Steinbach, Smith, D. (2000) pp.313-314) Causative factor Median nerve is compressed due to following reasons, (Steinbach, Smith, D. (2000) pp.313-314) 1. External pressure because of abnormal growth or mass (Malignancy) 2. After fracture-where bones are not fused correctly as per the normal anatomy. 3. Post traumatic carpel bones instability causing pressure over carpel Tunnel. 4. Inflammation of join and tendons, edema and fatty deposition etc. Muscles abnormalities and abrupt movements such as extended flexion at wrist can cause Median Nerve Compression. Clinical Diagnosis Physical symptoms and hand movements examination are always not clear for proper diagnosis and more tests are advised, Nerve in conduction test Magnetic Resonance Studies. (Steinbach, Smith, D. (2000) pp.313-314) MRI finding MRI is useful to identify the cause of compression of the median nerve when clinical features are not very clear. Median nerve is clearly seen on MRI. Axial view gives clear data about the structure and the position of the Median nerve. Median nerve position is changeable with the wrist flexion and extension and it is clearly seen on MRI. There are certain conditions where MRI is very important and compulsory. Those conditions are, (Steinbach, Smith, D. (2000) pp.313-314) 1. Electromyography report does not match with clinical presentation of the disease. 2. Inflammation, edematous condition such as Tenosynovitis. 3. In case of abnormal mass in the wrist 4. Preoperative-to visualize exact location of median nerve 5. Post operative- where symptoms are recurring due to Median nerve infection or neuroma etc (Steinbach, Smith, D. (2000) pp.313-314) 6. Palmer bowing of flexor retinaculum is also clear at the level of hook of Hamate. (Dick, Burnett, Gedroyc, (2007), pp.253.). References AAOS, (2007), Ganglion (Cyst) of the Wrist, American Society for Surgery of Hand. [Accessed: Mar 15, 2012], Available from: http://orthoinfo.aaos.org/topic.cfm?topic=a00006 Anderson, M, (2011), ACR–SPR–SSR PRACTICE GUIDELINE FOR THE PERFORMANCE AND INTERPRETATION OF MAGNETIC RESONANCE IMAGING (MRI) OF THE ELBOW, [Accessed: Mar 18, 2012]. Available from: http://www.acr.org/SecondaryMainMenuCategories/quality_safety/guidelines/dx/musc/mri_elbow.aspx Bianchi, S. Martinoli, C. , (n.p), Elbow 8 Dick, E. Burnett, C. Gedroyc, W, (23/1/2007), "MRI of the wrist", The Society and College of Radiographers, vol. 14. 10.1016/j.radi.2007.07.003, pp.253. Merriam Webster medical dictionary, [Accessed: Mar 15, 2012]. http://www.merriam-webster.com/dictionary/rotator%20cuff NHS, (2011), NHS Choices, Available from: UK. Gov, [Accessed: Mar 14, 2012] http://www.nhs.uk/Conditions/Tendonitis/Pages/Symptoms.aspx Serafini, G. Sconfienza, L. Lacelli, F, (2009), Rotator Cuff Calcific Tendonitis, Radiology. [Accessed: Mar 18, 2012].Available from: http://radiology.rsna.org/content/252/1/157.full.pdf Steinbach, L. Gunther, S. , (2000), "Magnetic Resonance Imaging of the Rotator Cuff", Seminars in Roentgenology, Jul 3, p.214. Steinbach, L. Smith, D. , 1st Initial, (2000), "MRI of the wrist", Journal of Clinical Imaging, vol. 24. , pp.313-314. Teh, J. Whitely, G., (2005), MRI of soft tissue masses of the hand and wrist, The British Journal of Radiology. [Accessed: Mar 16, 2012]. Available from: http://bjr.birjournals.org/content/80/949/47.full.pdf TJFP, (2003), Patient Information-Carpal Tunnel Syndrome, Journal of Family Practice. [Accessed: Mar 16, 2012].Available from: http://www.jfponline.com/Pages.asp?AID=1371&issue=January_2003&UID Trovinger, A. Sonin, A. Otte, M, (n.p), Musculoskeletal MRI part II: bony pelvis, knee, shoulder & elbow, Available from: CEwebsource.com, [Accessed: Mar 16, 2012]. http://www.cewebsource.com/coursePDFs/MusculoskeletalMRIpelvisknee.pdf Diagrams 1. Elbow Joint http://medicalpicturesinfo.com/?s=elbow+joint 2. Left elbow joint-Bones http://www.bartleby.com/107/illus330.html 3. Rotator Cuff- Anterior and posterior view http://www.aafp.org/afp/1998/0215/p667.html 4. Left hand Carpal Bones http://www.bartleby.com/107/54.html#i219 5. Ganglion http://orthoinfo.aaos.org/topic.cfm?topic=a00006Top of Form Bottom of Form Read More