Tibialis posterior tenosynovitis - Ultrasonography

48 year old male came with history of redness and swelling in the posteromedial aspect of the right ankle. Ultrasonography showed mildly thickened tibialis posterior tendon with significant amount of fluid collection around the tendon. No effusion in the ankle joint/ No DVT / No varicose veins. Features are consistent with tibialis posterior tenosynovitis.

Discussion:

Tenosynovitis is inflammation of tendon sheath. It can be caused by trauma, pyogenic infection, tuberculosis, seronegative spondylarthropathies or rheumatoid arthritis.

USG features are:

• Thickened tendon.
• Fluid collection around the tendon.
• Mildly increased vascularity within the tendon.

MRI features: Usually acute presentation. 

• Fluid collection around the tendon in its proximal aspect.
• Signal change within the tendon is usually not seen in the acute stage and will be seen in chronic stage.

We need to differentiate the tenosynovitis with the paratendonitis which occur more in the distal aspect of the tendon. paratendonitis seen on MR as partially circumferential high signal intensity located distally around the posterior tibialis tendon.  This signal intensity is usually slightly hypointense to fluid.

Tarlov Cyst

25 year old young male came with radicular pain to lower limb on right side referred for MRI LS spine. MRI T2 weighted para saggital image shows well defined rounded hyperintense lesion in the D12-L1 intervertebral foramen causing compression on the exiting nerve root on right side. CISS 3D axial image shows the lesion better (arrow).

Tarlov or perineurial cysts are pathological formations located in the space between the peri-and endoneurium of the spinal posterior nerve root sheath. Tarlov cysts are rare causes of low back pain. They are more common in females. Clinical presentation of Tarlov cysts is variable. The cysts may cause local and/or radicular pain. Depending on their location, size and relationship to the nerve roots, they may cause sensory disturbances or motor deficits to the point of bladder dysfunction.

Radiograph is usually normal, it may show bony erosion or widening of foramen on oblique views. Conventional myelography may show extradural indentation on the thecal sac however MRI is needed for confirmation of the lesion. CT scan can demonstrate cystic lesion isodense with CSF located at the foramina. Bony changes may also be present. MRI shows welldefined CSF intensity lesion in the prineural location predominantly in lumbar and sacral region. The lesions may be seen in the cauda equina and other nerve roots.

Supraspinatus Tendonitis

44 year old male patient came with painfull arc of shoulder movement, T1 weighted oblique coronal image shows hyperintense abnormal signal seen in the supraspinatous tendon (arrow).

Supraspinatus tendonitis is often associated with shoulder impingement syndrome. The common belief is that impingement of the supraspinatus tendon leads to supraspinatus tendonitis (inflammation of the supraspinatus/rotator cuff tendon and/or the contiguous peritendinous soft tissues), which is a known stage of shoulder impingement syndrome.

It is basically chronic degenerative tendinitis leading to some degree of mucoid degeneration seen on MRI as increased signal intensity without altered rotatory cuff contour. Increased signal intensity appreciated on T1 and PD weighted images.

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Spine fracture in Ankylosing Spondylitis

38 year old male patient with ankylosing spondylitis met with mild trauma following which he presented with para paresis, Sagittal T2 weighted MR image showing anterior displacement of C6 over C7 (Arrow head) and multiple syndesmophytes in all the cervical levels (short arrow). There is cord hyperintensity at the levels of C6, C7 and D1 suggestive of cord contusion due to fracture.

The diffuse paraspinal ossification and inflammatory osteitis of advanced ankylosing spondylitis creates a fused, brittle spine that is susceptible to fracture. Even minor trauma can produce an unstable injury as a result of disruption of the ossified supporting ligaments.

Thoracolumbar fractures are reported less frequently than cervical injuries in patients with ankylosing spondylitis.Three recognized patterns are simple vertebral compression fractures, transversely oriented shear fractures, and stress fractures associated with pseudoarthrosis. Transversely oriented shear fractures are acute fractures of the ankylosed spine that invariably disrupt the ossified supporting ligaments and usually traverse the disk space. Disruption of all three columns of the spine predisposes the fracture to displacement and neurologic injury. Stress fractures associated with pseudoarthrosis are subacute injuries that constitute part of the spectrum of spondylodiscitis, a destructive discovertebral (“Andersson”) lesion, that tends to occur in the thoracolumbar region. End-plate erosions and disk height changes, with vertebral sclerosis or osteolysis, can be seen radiographically.

Shiny corner sign in Ankylosing Spondylitis

38 year old male with recently diagnosed ankylosing spondylitis, lateral lumbar spine radiograph showing increased density (arrow) in the anteroinferior part of L3 vertebral body suggetive of shiny corner sign. MR STIR image shows increased signal in anteroinferior parts (arrows) of L3 and L5 bodies.

Shiny corner sign, also known as a Romanus lesion, is an early spinal finding in ankylosing spondylitis. These represent small erosions at the superior and inferior endplates (corners on lateral radiograph) of the vertebral bodies, with surrounding reactive sclerosis. Eventually the vertebral bodies become squared.

On MRI the 'shiny corners' appear as areas of increased T1 signal due to focal fatty marrow as a result of chronic inflammation. MRI however can detect changes earlier than x-ray manifestations, when there is initially increased T2 signal on STIR and decreased signal on T1WI. At this stage plain films appear normal.