How to Read Abnormal Hand Wrist Mri

SA-CME LEARNING OBJECTIVES

After completing this journal-based SA-CME activeness, participants volition exist able to:

■ Identify the normal advent of the wrist tendons and know the six extensor compartments and which tendons they contain.
■ Recognize common infectious and inflammatory pathologic conditions affecting the wrist tendons.
■ Describe the appearance of common proliferative processes associated with wrist tendons.

Introduction

There are a multitude of tendons in the wrist. It can be a daunting chore to keep them all in mind. Wrist hurting is mutual, and with diagnostic imaging oftentimes readily available, patients are often referred for imaging to find the cause of pain.

Radiography remains the first line of diagnostic imaging for the evaluation of the wrist. Just both magnetic resonance (MR) imaging and ultrasonography (United states of america) are useful tools for evaluating the wrist. U.s. is a suitable imaging method for the wrist tendons, equally it is fast and relatively inexpensive and also has the advantages of offering the ability to examine the patient under conditions of dynamic movement and to target the exact site of hurting or symptoms. Equally the wrist tendons are superficial, the probe tin exist directly placed over them, thus acquiring fantabulous resolution and anatomic detail. MR imaging also provides high-quality images of the tendons, with the added advantage of detecting other abnormalities of the bones or cartilage, which may not be apparent at US. Computed tomography (CT) usually plays a limited role in wrist pain diagnosis and its utilization is reserved for few selected diagnoses.

In this article, we will review the normal anatomy and appearance of the tendons of the wrist and then present examples of common pathologic atmospheric condition at MR imaging and United states.

Imaging Technique

MR imaging is carried out in the standard axial, sagittal, and coronal planes. Both T1-weighted and fluid-sensitive fat-saturated sequences should exist performed to properly evaluate the tendons of the wrist. A gradient-echo sequence is commonly included in routine wrist imaging protocols for evaluation of cartilage and internal derangements and may take a part in diagnosis of sure tendinous pathologic conditions. The best images can be obtained with a dedicated wrist coil.

United states of america requires a loftier-frequency linear probe (10–15 MHz). Each extensor compartment tin be evaluated with the probe placed directly over the tendon; given the superficial and bony nature of the wrist, copious amounts of gel or a standoff pad will assistance with this. The flexor tendons take less separation between them, particularly in the carpal tunnel, just can nonetheless exist imaged individually. Each tendon should be assessed along its entire length in both the axial and longitudinal planes.

Near of the fourth dimension, US examinations of the wrist are focused examinations, which aim to answer a specific clinical question, or are directed to examine a focal site of hurting or abnormality. A thorough exam of each individual structure and element of the wrist is not routinely done.

A mutual pitfall in U.s.a. of tendons is anisotropy.

Tendons have a fibrillated morphologic structure, which causes the reflected audio-visual waves to be dispersed if the US probe is not directly perpendicular to the tendon. In that case, the tendon will appear hypoechoic or indistinct—an abnormal appearance, but one that is purely artifactual and hands checked by repositioning the probe perpendicular to the tendon.

Figure 1 shows the effects of anisotropy on the tendons. The normal tendons are echogenic, merely with a slight shift of the probe off the perpendicular airplane, the tendons appear abnormal and hypoechoic. It is of import to keep this artifact in listen, equally anisotropy can mimic pathologic conditions such as tendinopathy.

Figure 1a. Transverse U.s. images of the wrist showing the flexor tendons (arrows). G = median nervus. **(a)** Anisotropic orientation of the United states of america probe causes the tendons to announced ill-defined and hypoechoic. **(b)** Once the probe is properly repositioned, the normal echogenic advent of the tendons is demonstrated.

Figure 1b. Transverse The states images of the wrist showing the flexor tendons (arrows). *Yard* = median nerve. **(a)** Anisotropic orientation of the U.s.a. probe causes the tendons to appear ill-defined and hypoechoic. **(b)** Once the probe is properly repositioned, the normal echogenic advent of the tendons is demonstrated.

Other pitfalls include misinterpreting the flexor retinaculum, which normally appears as a thickened ring roofing the carpal tunnel, as pathologically thickened tendon sheaths from tenosynovitis. Nonetheless, this can be avoided once one becomes familiar with the normal advent of the flexor retinaculum.

Anatomy

The tendons of the wrist are divided into two primary groups: the flexor tendons and the extensor tendons. The extensor tendons are divided into six compartments. Figure 2 shows a cross-sectional diagram of the extensor compartments. Each compartment has its own divide tenosynovial sheath.

Figure 2. Schematic cross-sectional diagram of the wrist at the level of the Lister tubercle shows the partition of the six extensor tendon compartments (indicated by their respective Roman numerals) and the flexor tendons.

The showtime compartment contains the abductor pollicis longus (APL) and the extensor pollicis brevis (EPB) tendons. The APL originates at the mid-ulna and inserts onto the base of the start metacarpal bone. It serves to abduct and extend the thumb. The EPB tendon originates at the distal radius and inserts at the base of the first proximal phalanx. Information technology extends the proximal phalanx across the first carpal-metacarpal joint.

There can be variant anatomy within the start extensor compartment. In that location may be a thin septum (visible as a thin echogenic line at US) between the APL tendon and the EPB tendons, which splits the compartment into two subcompartments. It has been suggested that this is more common in patients with de Quervain tenosynovitis (1).

The 2d compartment contains the extensor carpi radialis longus and extensor carpi radialis brevis tendons. The extensor carpi radialis longus originates from the supracondylar lateral distal humerus and inserts at the base of the second metacarpus. The extensor carpi radialis brevis tendon originates from the lateral epicondyle of the distal humerus and inserts at the base of the third metacarpus. Both of these muscles extend and abduct the hand at the level of the wrist.

The third compartment contains the extensor pollicis longus tendon, which originates at the mid-ulna and inserts at the base of the showtime distal phalanx. In combination with the EPB tendon, it extends the thumb at the first carpometacarpal and first interphalangeal joints.

The fourth compartment contains the extensor digitorum and extensor indicis tendons. The extensor digitorum tendon originates from the lateral epicondyle of the distal humerus, divides into four distinct tendons, then inserts onto the middle and distal phalanges of the 2d, third, and fourth fingers. It serves to extend the hand at the wrist and extend the fingers at the metacarpophalangeal (MCP) joints. The extensor indicis originates from the posterior ulna and inserts onto the center phalanx (anatomically the extensor expansion) of the second digit, helping to extend the second digit.

The fifth compartment contains the extensor digiti minimi tendon, which originates from the lateral humeral epicondyle and attaches onto the center phalanx (extensor expansion) of the 5th finger. Information technology extends the 5th finger at the MCP and interphalangeal joints.

The sixth compartment contains the extensor carpi ulnaris (ECU) tendon, which originates from the lateral humeral epicondyle and posterior ulna. It inserts onto the base of operations of the fifth metacarpal and serves to extend and adduct the manus at the level of the wrist.

The majority of flexor tendons travel through the carpal tunnel, which is divisional volarly by the flexor retinaculum tendon, but, dissimilar in the extensor compartments, there are no distinct compartments for the flexor tendons. Three of the flexor tendons remain outside the carpal tunnel. These include the flexor carpi ulnaris tendon, which attaches to the pisiform bone, the flexor carpi radialis tendon, and the palmaris longus tendon. The palmaris longus tendon is not nowadays in anybody; a minority of people lack information technology. It tin be harvested for use in ligamentous reconstructions.

The Lister tubercle is a bone landmark along the dorsum of the distal radius, which is useful in helping to separate the second and third extensor compartments. Figure iii shows the Lister tubercle and the extensor tendons on an centric T1-weighted MR image of the wrist.

Figure 3. — Effigy 3. Centric T1-weighted MR image through the wrist shows the Lister tubercle (arrow). It serves as a user-friendly bone landmark, separating the second from the third extensor compartments. The extensor compartments are labeled with their respective Roman numerals.

U.s.a. Appearance

At U.s., a normal tendon is a long bright echogenic fibrillated structure (Fig 4a). In the axial plane, information technology appears ovoid in cross-section and its dissever fascicles announced as individual dots. Longitudinally, it appears as a long straight structure with multiple parallel fascicles (Fig 4b).

Figure 4a. Normal wrist tendons in a 42-year-old man. Longitudinal **(a)** and transverse **(b)** US images of a normal wrist extensor tendon (arrows). In the long axis, the tendon appears every bit an echogenic structure with multiple thin parallel fibrillations. In the short axis, information technology is a well-defined echogenic ovoid structure.

Figure 4b. Normal wrist tendons in a 42-year-old homo. Longitudinal **(a)** and transverse **(b)** Usa images of a normal wrist extensor tendon (arrows). In the long axis, the tendon appears as an echogenic structure with multiple thin parallel fibrillations. In the curt centrality, information technology is a well-defined echogenic ovoid construction.

The synovial sheaths that surround the tendons appear as thin echogenic lines outlining or surrounding the tendon. In that location may be a normal amount of anechoic fluid within the tendon sheath surrounding the tendons. This fluid should appear as a thin dark rim effectually the brilliant echogenic tendon, and is commonly not more than 2 mm in thickness (2).

Tendinopthic tendons will appear at United states to be enlarged and heterogeneous with areas of hypoechogenicity and irregularity. Tenosynovitis will appear as fluid with echogenic debris surrounding the tendon and within the tendon sheath. Specific examples of this are detailed later.

MR Imaging Appearance

At MR imaging, tendons are distinct black bundles that are easily imaged along the path to their insertion sites. Their advent should not differ between T1- and T2-weighted sequences, although the tenosynovial fluid surrounding them will be more apparent at the fluid-sensitive sequences. Effigy 5 shows the normal advent of the wrist tendons at MR imaging.

Figure 5. — Effigy 5. Normal appearance of the wrist in an xviii-twelvemonth-old adult female. Axial T1-weighted MR image shows the extensor and flexor tendons. The individual extensor tendon compartments are labeled with their corresponding Roman numerals; the private flexor tendons and ii fretfulness are indicated with letters. A = flexor carpi ulnaris, B = flexor digitorum profundus, C = flexor carpi radialis, D = flexor pollicis longus, E = flexor digitorum superficialis, *One thousand* = median nervus, U = ulnar nervus.

Tendinopathic tendons volition appear as thickened and heterogeneous with areas of loftier T2 signal intensity in the tendon. Tenosynovitis around the tendons appears as increased fluid surrounding the tendon and with areas of thickened and irregular dark wavy lines inside the tendon sheath.

Pathologic Conditions

de Quervain Tenosynovitis

The APL and EPB tendons contain the contents of the start extensor compartment, which lies along the dorsolateral aspect of the wrist. These tendons overlie the radial styloid, are held in place by the overlying extensor retinaculum, and are variably separated by a septum (ane,3,four). As mentioned in the anatomy section, this septum, which can range from partial to complete, may predispose to developing de Quervain tenosynovitis. This tin go important in treating the disease, equally a steroid injection in the first extensor compartment may not disperse around both tendons if there is an intervening septum, and thus ii split up injections may exist required if a septum is discovered (iii,4). In ane cadaveric study, upwards to forty% of studied wrists showed at least some degree of septation within the start extensor compartment (3).

The showtime compartment tendons can become damaged and thickened as a outcome of repetitive microtrauma involving the thumb; such patients complain of pain and swelling at the radial aspect of the wrist, which tin can exist reproduced by provocative maneuvers such equally the Finkelstein examination. This is de Quervain tenosynovitis.

Although the diagnosis of de Quervain tenosynovitis is most frequently made clinically, corresponding findings are readily apparent at imaging, which can as well be helpful in excluding other causes for radial-side wrist pain. Figure 6a demonstrates the typical thickening of the APL and EPB seen on T1-weighted MR images. The concomitant regional soft-tissue hyperemic changes are well visualized on T2-weighted fat-saturated images (Fig 6b). Conscientious evaluation should be fabricated for fluid inside the tendon sheath, and for whatever evidence of tendon tear. Bone marrow edema may exist present inside the underlying radius.

Figure 6a. **(a, b)** de Quervain tenosynovitis in a 42-yr-old adult female. **(a)** Axial T1-weighted MR prototype of the wrist demonstrates enlarged and irregular APL and EPB tendons within the first extensor compartment (arrow). The tendons are not homogeneously hypointense, but have areas of hyperintensity. **(b)** Corresponding T2-weighted fatty-saturated MR image at the same level demonstrates hyperintense edema nigh and inside the first compartment tendons (arrow). **(c, d)** de Quervain tenosynovitis in a 35-year-erstwhile woman. **(c)** Transverse The states image shows the relatively normal echogenic APL tendon (*), in this instance surrounded by echogenic synovitis (arrow). **(d)** At longitudinal United states of america of the tendon, we see the normal tendon (*) surrounded past the echogenic synovitis (arrows); the full extent of the synovitis is demonstrated here.

Figure 6b. **(a, b)** de Quervain tenosynovitis in a 42-year-quondam woman. **(a)** Axial T1-weighted MR image of the wrist demonstrates enlarged and irregular APL and EPB tendons within the first extensor compartment (arrow). The tendons are non homogeneously hypointense, but have areas of hyperintensity. **(b)** Respective T2-weighted fat-saturated MR image at the same level demonstrates hyperintense edema about and within the first compartment tendons (arrow). **(c, d)** de Quervain tenosynovitis in a 35-year-old adult female. **(c)** Transverse US epitome shows the relatively normal echogenic APL tendon (*), in this example surrounded past echogenic synovitis (arrow). **(d)** At longitudinal US of the tendon, we see the normal tendon (*) surrounded past the echogenic synovitis (arrows); the full extent of the synovitis is demonstrated hither.

Figure 6c. **(a, b)** de Quervain tenosynovitis in a 42-twelvemonth-old woman. **(a)** Axial T1-weighted MR prototype of the wrist demonstrates enlarged and irregular APL and EPB tendons inside the first extensor compartment (arrow). The tendons are non homogeneously hypointense, but have areas of hyperintensity. **(b)** Respective T2-weighted fat-saturated MR epitome at the same level demonstrates hyperintense edema about and within the first compartment tendons (arrow). **(c, d)** de Quervain tenosynovitis in a 35-twelvemonth-erstwhile woman. **(c)** Transverse Us image shows the relatively normal echogenic APL tendon (*), in this example surrounded past echogenic synovitis (pointer). **(d)** At longitudinal U.s. of the tendon, nosotros see the normal tendon (*) surrounded past the echogenic synovitis (arrows); the total extent of the synovitis is demonstrated here.

Figure 6d. — Effigy 6d. **(a, b)** de Quervain tenosynovitis in a 42-year-old woman. **(a)** Axial T1-weighted MR paradigm of the wrist demonstrates enlarged and irregular APL and EPB tendons inside the first extensor compartment (arrow). The tendons are not homogeneously hypointense, merely have areas of hyperintensity. **(b)** Respective T2-weighted fatty-saturated MR image at the aforementioned level demonstrates hyperintense edema nigh and inside the beginning compartment tendons (pointer). **(c, d)** de Quervain tenosynovitis in a 35-year-old adult female. **(c)** Transverse The states image shows the relatively normal echogenic APL tendon (*), in this example surrounded past echogenic synovitis (arrow). **(d)** At longitudinal U.s.a. of the tendon, we see the normal tendon (*) surrounded by the echogenic synovitis (arrows); the total extent of the synovitis is demonstrated here.

At US, the abnormal APL and EPB tendons announced thickened (comparison with the contralateral side can exist helpful), with possible thickening of and fluid within the tendon sheath, regional hypoechoic edema fluid, and increased flow on color or power Doppler images. The overlying extensor retinaculum may likewise appear thickened (iv). Figures 6c and 6d bear witness the US advent of de Quervain tenosynovitis; in this patient, the relatively normal actualization echogenic tendon is surrounded past echogenic synovitis in the first extensor compartment.

ECU Tendinopathy

The ECU tendon is found inside the 6th extensor compartment, and passes inside a dorsal groove along the distal ulna before inserting onto the base of the fifth metacarpal. At the level of the distal ulna, the ECU is held in place by a subsheath, by the overlying extensor retinaculum, and by stabilizing fibers of the linea jugata, which extends from the base of the ulnar styloid process to the extensor retinaculum. This subsheath tin can become injured and lead to subluxation or dislocation of the ECU tendon even if the overlying extensor retinaculum is intact. This is a rare injury that tin crusade the ECU tendon to repeatedly dislocate in the ulnar direction, often with a characteristic audible snap (5). Figure 7 shows a schematic of the ECU tendon and its overlying subsheath. The position of the ECU should exist advisedly scrutinized to exclude ECU subluxation, which can lead to pain and snapping of the tendon in supination or ulnar divergence, every bit seen in Figure 8. This figure shows ulnar subluxation of the ECU tendon associated with a tear of the subsheath. The overlying extensor retinaculum is intact. Test should also be made for evidence of a longitudinal split up tear, or tendon sheath fluid to propose tenosynovitis.

Figure 7a. **(a)** Schematic cross-sectional diagram of the distal ulna shows the ECU tendon (*) usually positioned in its groove. The red arrow points to the overlying subsheath, which holds the ECU tendon in place. The black arrow points to the overlying extensor retinaculum. Tears of the ECU subsheath tin can cause subluxation or dislocation of the tendon. **(b)** Schematic cross-sectional diagram of the distal ulna shows the ECU tendon (*) subluxated in the ulnar management with a tear (pointer) of the subsheath.

Figure 7b. **(a)** Schematic cross-sectional diagram of the distal ulna shows the ECU tendon (*) ordinarily positioned in its groove. The ruby-red arrow points to the overlying subsheath, which holds the ECU tendon in place. The black arrow points to the overlying extensor retinaculum. Tears of the ECU subsheath can cause subluxation or dislocation of the tendon. **(b)** Schematic cross-sectional diagram of the distal ulna shows the ECU tendon (*) subluxated in the ulnar direction with a tear (pointer) of the subsheath.

Figure 8. — Effigy 8. Subluxation and tendinosis of the ECU tendon in a 36-year-old man. Axial T1-weighted fat-saturated image from an MR imaging arthrogram, which shows the ECU tendon (*) subluxated in the ulnar direction. The overlying subsheath is torn (arrow) and therefore not visible. Also note at that place is some hyperintensity within the ECU tendon, reflecting tendinopathy.

As for all tendons, the ECU can be affected by repetitive microtrauma. In particular, repeated ulnar difference can atomic number 82 to tendinosis and/or tenosynovitis; the ECU is the second well-nigh common site of upper extremity tenosynovitis (half-dozen).

Figure 9 shows the normal US advent of the ECU tendon. It is round and uniformly hyperechoic.

Figure 10 shows the MR imaging appearance of ECU tendinopathy and tenosynovitis. At MR imaging, the tendon is thickened and irregular with areas of T2 hyperintensity. Surrounding fluid and irregularity of the tendon sheath reflect tenosynovitis.

Figure 10a. Tendinosis and tenosynovitis of the ECU tendon in a 42-year-old adult female. **(a)** Axial T1-weighted MR image shows thickening and abnormal intermediate signal intensity (arrow) within an irregular ECU tendon. **(b)** Axial T2-weighted fat-saturated MR image at a slightly more distal location along the wrist. The ECU tendon (arrow) is surrounded past abnormal hyperintense fluid (*); there is hyperintense edema within the tendon. These findings are typical of tendinopathy and tenosynovitis.

Figure 10b. — Effigy 10b. Tendinosis and tenosynovitis of the ECU tendon in a 42-yr-one-time adult female. **(a)** Axial T1-weighted MR epitome shows thickening and abnormal intermediate signal intensity (pointer) within an irregular ECU tendon. **(b)** Axial T2-weighted fat-saturated MR image at a slightly more distal location along the wrist. The ECU tendon (pointer) is surrounded past abnormal hyperintense fluid (*); there is hyperintense edema within the tendon. These findings are typical of tendinopathy and tenosynovitis.

Rheumatoid Tenosynovitis

The tendons virtually the wrist are surrounded by a synovial sheath, and every bit such are at gamble for synovium-based inflammatory processes. These include rheumatoid arthritis (RA), an autoimmune process usually centered on the synovium of the wrist and easily.

Tendon involvement is mutual in RA, and has been estimated to occur within the extensor compartment of the wrist in l%–64% of RA patients (vii). Inside the extensor compartment, the ECU has been reported as the almost unremarkably affected tendon in early RA patients (8). In addition to severe pain and disfigurement, chronic synovial inflammation tin can predispose a patient to tendon rupture.

At MR imaging, RA involvement of the tendons manifests with synovial hypertrophy and soft-tissue thickening and inflammatory changes likewise every bit presence of tendon sheath fluid. This may eventually effect in formation of a discrete tenosynovial pannus

(Fig xi). The inflamed synovium can demonstrate intense enhancement after administration of dissimilarity medium. Attenuation of the tendon is a worrisome sign for possible impending rupture.

Figure 11. — Figure eleven. Advanced RA in a 57-year-one-time woman. Centric T2-weighted fatty-saturated image demonstrates diffuse tenosynovial soft-tissue thickening and hypertense inflammatory changes involving the extensor tendons, particularly the fourth compartment (arrow). The tendons themselves appear normal. There is marked pannus and inflammation (*) almost the wrist.

At US, tenosynovitis appears as thickened echogenic areas often surrounded by tenosynovial fluid. Power Doppler US is a useful tool to evidence hyperemia associated with the inflammation. Figure 12 shows tenosynovitis of the quaternary extensor compartment, demonstrated at United states of america.

Figure 12a. Rheumatoid arthropathy in a 56-year-one-time human. **(a)** Longitudinal United states of america of the fourth extensor compartment shows a normal-appearing tendon (*) surrounded by dark anechoic tenosynovial fluid and thick echogenic areas of synovitis (arrows) within the tendon sheath. **(b)** Axial Usa image of the aforementioned extensor compartment shows the thickened synovial sheath (arrows) with areas of echogenic synovitis within the fluid distending the tendon sheath. The tendons (*) are normal in appearance. With a ability Doppler overlay, we see areas of hyperemia indicative of agile inflammation.

Figure 12b. Rheumatoid arthropathy in a 56-twelvemonth-erstwhile man. **(a)** Longitudinal Us of the fourth extensor compartment shows a normal-appearing tendon (*) surrounded by dark anechoic tenosynovial fluid and thick echogenic areas of synovitis (arrows) within the tendon sheath. **(b)** Centric United states of america image of the same extensor compartment shows the thickened synovial sheath (arrows) with areas of echogenic synovitis within the fluid distending the tendon sheath. The tendons (*) are normal in advent. With a power Doppler overlay, nosotros see areas of hyperemia indicative of agile inflammation.

Infectious Synovitis

Infectious (or suppurative) tenosynovitis about the wrist is nearly commonly related to penetrating injuries such every bit stab or seize with teeth wounds or injectable drug use. Less ordinarily, it may relate to direct extension of an adjacent soft-tissue infection or hematogenous dissemination of localized infection elsewhere. Infectious tenosynovitis was originally thought to near commonly involve the flexor tendons, withal this may no longer be true given the prevalence of intravenous drug abuse (9). The causative organism varies by etiology, including Staphylococcus or Streptococcus species in the case of injection, polymicrobial infection in the example of bite wound, and Neisseria in the setting of sexually transmitted affliction. Less common sources include typical and atypical Mycobacterium infection as well as anaerobic infection in diabetic patients (x).

At MR imaging, infectious tenosynovitis is characterized past loftier T2 signal intensity fluid inside the tendon sheath. Depending on the nature of the textile, this may be purely fluid betoken intensity (low T1) or of intermediate T1 signal intensity corresponding with pus or debris. Discrete filling defects within the fluid may reflect rice bodies in the setting of tuberculous tenosynovitis (xi). The tendons themselves, normally ovoid and uniformly low in T1 and T2 signal intensity, can become enlarged, inhomogeneous, and increased in point intensity. Increased contrast enhancement tin also be seen.

Figure 13 shows the effects of advanced infectious synovitis about the wrist with associated bone erosions.

Figure 13a. Infectious tenosynovitis of the wrist in a 58-year-old man. **(a)** Centric T2-weighted MR image of the wrist at the level of the distal radius and ulna. In that location is fluid (*) distending the ECU tendon sheath, with enlargement and heterogeneous signal intensity (arrow) of the tendon. **(b, c)** Coronal T1- **(b)** and T2-weighted fat-saturated **(c)** MR images of the wrist demonstrate associated findings in this case of infectious ECU tenosynovitis that has spread to involve the entire wrist. At that place is fluid and droppings within the distended distal radioulnar joint (*), erosion (arrows) of the distal radius and ulna, and subversive changes to the carpus. Diffuse bone marrow edema is present and is related to the massive infection.

Figure 13b. Infectious tenosynovitis of the wrist in a 58-yr-old man. **(a)** Axial T2-weighted MR prototype of the wrist at the level of the distal radius and ulna. At that place is fluid (*) distending the ECU tendon sheath, with enlargement and heterogeneous signal intensity (arrow) of the tendon. **(b, c)** Coronal T1- **(b)** and T2-weighted fat-saturated **(c)** MR images of the wrist demonstrate associated findings in this case of infectious ECU tenosynovitis that has spread to involve the entire wrist. There is fluid and debris within the distended distal radioulnar joint (*), erosion (arrows) of the distal radius and ulna, and destructive changes to the carpus. Lengthened bone marrow edema is present and is related to the massive infection.

Figure 13c. Infectious tenosynovitis of the wrist in a 58-twelvemonth-old human being. **(a)** Axial T2-weighted MR image of the wrist at the level of the distal radius and ulna. There is fluid (*) distending the ECU tendon sheath, with enlargement and heterogeneous signal intensity (pointer) of the tendon. **(b, c)** Coronal T1- **(b)** and T2-weighted fat-saturated **(c)** MR images of the wrist demonstrate associated findings in this instance of infectious ECU tenosynovitis that has spread to involve the unabridged wrist. There is fluid and droppings within the distended distal radioulnar joint (*), erosion (arrows) of the distal radius and ulna, and destructive changes to the carpus. Diffuse bone marrow edema is present and is related to the massive infection.

Similar findings can be seen at United states of america, that is, tendon sheath fluid, tendon thickening and inhomogeneity, and rice bodies. Hyperemia is seen as increased Doppler signal inside the tendon sheath, or more rarely within the tendon (12). Usa can also be used to demonstrate hypoechoic thickening of the tenosynovial sheath itself, and tin be used to guide needle aspiration for culture and sensitivity testing (thirteen).

Tendon Tears

Astute tendon tears are typically avulsive in nature and involve the distal insertions. Midsubstance tears are less common and usually relate to lacerations. Exceptions include cases in which the tendon is weakened by chronic conditions such as RA, repeated steroid injection, or next orthopedic hardware (xiv). Case reports too exist of traumatic rupture related to underlying connective tissue disease such as Ehlers-Danlos syndrome (15).

Tendon tears tin be evaluated at either MR imaging or U.s.a.. It has been suggested that US is particularly suited to evaluation of the extensor pollicis longus tendon, equally the orientation of this tendon makes it prone to magic angle artifact and therefore difficult to examine at MR imaging (16). Tendon tears are seen as focal attenuation or aperture of the tendon, with intervening fluid that appears hypoechoic at US and T2 hyperintense at MR imaging (17). Interstitial tears are seen forth the longitudinal axis of the tendon.

Figure 14 shows a complete tear of the flexor pollicis longus (FPL) tendon caused by a kitchen knife injury, where in that location is a complete gap between the two fragments. At that place is claret and fluid between the intervening tendon sections.

Figure 15 shows a complete tear of the palmaris longus tendon post-obit a hyperextension injury. When scrolling through axial paradigm sequences, the tendon tear can be recognized by a sequence where the hypointense tendon disappears or becomes severely adulterate.

Figure 15a. Complete tear of the palmaris longus tendon in a 36-year-sometime man who had a hyperextension injury of the wrist and heard a loud pop. He was focally tender forth the volar attribute of his wrist. **(a)** Axial T2-weighted fat-saturated MR prototype of the wrist, only proximal to the tear, shows the palmaris longus tendon (arrow) even so intact, although there is some hyperintense fluid surrounding it. **(b)** More than distally, at that place is complete absence of the normal hypointense tendon; all that remains is fluid and synovitis (arrow) in its expected location. **(c)** Coronal T2-weighted fat-saturated MR image of the wrist shows the torn section (arrows) of the palmaris longus tendon. Minor wisps of hypointense tendon fibers are all that remain.

Figure 15b. Complete tear of the palmaris longus tendon in a 36-twelvemonth-sometime man who had a hyperextension injury of the wrist and heard a loud pop. He was focally tender along the volar aspect of his wrist. **(a)** Axial T2-weighted fat-saturated MR image of the wrist, but proximal to the tear, shows the palmaris longus tendon (arrow) still intact, although there is some hyperintense fluid surrounding information technology. **(b)** More than distally, there is consummate absence of the normal hypointense tendon; all that remains is fluid and synovitis (pointer) in its expected location. **(c)** Coronal T2-weighted fatty-saturated MR epitome of the wrist shows the torn department (arrows) of the palmaris longus tendon. Small wisps of hypointense tendon fibers are all that remain.

Figure 15c. Complete tear of the palmaris longus tendon in a 36-year-old man who had a hyperextension injury of the wrist and heard a loud pop. He was focally tender forth the volar aspect of his wrist. **(a)** Centric T2-weighted fat-saturated MR image of the wrist, just proximal to the tear, shows the palmaris longus tendon (arrow) however intact, although in that location is some hyperintense fluid surrounding it. **(b)** More than distally, there is complete absence of the normal hypointense tendon; all that remains is fluid and synovitis (pointer) in its expected location. **(c)** Coronal T2-weighted fatty-saturated MR image of the wrist shows the torn section (arrows) of the palmaris longus tendon. Small wisps of hypointense tendon fibers are all that remain.

At US, tendon tears appear as attenuation or defects within the tendon or, in cases of a complete tear, a focal discontinuity betwixt the ii tendon ends. Figure 16 shows a complete tear of the flexor pollicis longus tendon. The tear is recognizable by a consummate loss of whatsoever normal-appearing tendon fibers, which abruptly beginning at the level of the tear. All that remains in the expected location of the tendon is hypoechoic fluid.

Figure 16. Consummate tear of the FPL tendon in an 81-year-one-time human. Longitudinal Usa prototype shows an sharp end (arrow) to the normal echogenic tendon fibers. In the expected location (*) of the tendon at that place is hypoechoic fluid.

In the case of a complete tear, the torn ends may appear tendinopathic with increased diameter and/or signal intensity (17). Measuring the size of the intervening gap is important every bit information technology may impact surgical planning for primary repair. Low-class or fractional tears are seen as focal hypoechoic signal at Us, and tin can be difficult to distinguish from focal tendinopathy. Evaluation for retear of previously repaired tendons can be similarly circuitous, with wide variations in advent and limited correlation with functional deficits (18).

Hydroxyapatite Deposition Illness

Calcium hydroxyapatite degradation, as well referred to as calcific tendinopathy, calcific peritendinopathy, or calcific bursitis, tin can occur in many places throughout the body, including in the wrist. It may be an asymptomatic incidental finding found at imaging of the wrist, but it can exist a crusade of acute and severe pain.

Most patients with calcium hydroxyapatite deposition are middle aged. The exact cause of the calcium deposition is not clear. The condition manifests as the deposition of calcium hydroxyapatite crystals in or around tendons or bursae. The size can vary from small to quite large. At radiography, the calcium deposits appear as ovoid opaque areas or attenuating ovoid areas at CT, which may be inside tendons (equally commonly seen almost the shoulder) or around them in the tendon sheath (xix,xx).

At The states, the calcium deposits appear as echogenic, and sometimes as shadowing areas in or around tendons.

Figure 17 shows a radiograph and corresponding Usa images of a patient with calcium hydroxyapatite deposition in the flexor carpi ulnaris tendon. On the radiograph, the calcium degradation is clearly visible as a focal calcific opacity merely volar to the pisiform. The diagnosis may be confirmed at U.s.a., when the focal calcium eolith is visible embedded within the flexor carpi ulnaris tendon.

Figure 17a. Calcific tendinopathy in a 52-year-erstwhile adult female due to volar-sided wrist hurting. **(a)** Lateral radiograph of the wrist shows a focal calcification (arrow) in the soft tissues merely volar to the pisiform bone. This corresponded to the patient'due south pain. On the footing of the radiograph, she was diagnosed with calcific tendinosis. She went on to further evaluation at U.s., which helped to ostend the diagnosis and showed the exact tendon involved. **(b)** Transverse Us image of the wrist shows the flexor carpi ulnaris tendon (arrow) associated with calcium hydroxyapatite deposition. At US, this is an oval echogenic focus (*) embedded within the tendon, corresponding to the calcific opacity on the radiograph. *PIS* = pisiform os. **(c)** Longitudinal US image shows the calcific deposition (*) associated with the tendon (arrow).

Figure 17b. Calcific tendinopathy in a 52-year-old woman due to volar-sided wrist pain. **(a)** Lateral radiograph of the wrist shows a focal calcification (pointer) in the soft tissues just volar to the pisiform os. This corresponded to the patient'due south pain. On the basis of the radiograph, she was diagnosed with calcific tendinosis. She went on to further evaluation at U.s., which helped to ostend the diagnosis and showed the verbal tendon involved. **(b)** Transverse United states image of the wrist shows the flexor carpi ulnaris tendon (pointer) associated with calcium hydroxyapatite degradation. At US, this is an oval echogenic focus (*) embedded within the tendon, corresponding to the calcific opacity on the radiograph. *PIS* = pisiform bone. **(c)** Longitudinal US prototype shows the calcific deposition (*) associated with the tendon (pointer).

Figure 17c. — Effigy 17c. Calcific tendinopathy in a 52-year-erstwhile woman due to volar-sided wrist pain. **(a)** Lateral radiograph of the wrist shows a focal calcification (arrow) in the soft tissues just volar to the pisiform bone. This corresponded to the patient's hurting. On the ground of the radiograph, she was diagnosed with calcific tendinosis. She went on to farther evaluation at US, which helped to confirm the diagnosis and showed the verbal tendon involved. **(b)** Transverse U.s.a. epitome of the wrist shows the flexor carpi ulnaris tendon (pointer) associated with calcium hydroxyapatite deposition. At U.s.a., this is an oval echogenic focus (*) embedded within the tendon, corresponding to the calcific opacity on the radiograph. *PIS* = pisiform bone. **(c)** Longitudinal US prototype shows the calcific deposition (*) associated with the tendon (arrow).

It tin can be trickier to notice calcific tendinopathy at MR imaging, equally the calcification appears as low signal intensity on both T1- and T2-weighted MR images, which is similar to the tendon. Thus, in that location is little visual distinction betwixt the calcification and the normal tendon. Nevertheless, careful examination may reveal profile abnormalities of the calcification separate from the tendon, or at that place may be some side by side edema, which would help to divide the calcification from the tendon.

Intersection Syndrome

2 intersection syndromes accept been described in the forearm and wrist, both representing noninfectious processes related to repetitive stress or trauma to the extensor tendon compartments. The more common form (known variously as proximal intersection syndrome, crossover syndrome, peritendinitis crepitans, and oarsmen's wrist, among others) characteristically occurs at a location four–eight cm proximal to the Lister tubercle where the beginning extensor compartment tendons (the APL and EPB) cross over the second extensor compartment tendons (the extensor carpi radialis longus and brevis) (21). Figure 18 shows the site of the tendon crossover where the inflammation can occur. A real-time scan of the first extensor compartment tendons is shown in the online Picture show, and shows a crossing over of the second extensor compartment tendons. Distal intersection syndrome is much less mutual and relates to the more distal site where the third extensor compartment tendon (the extensor pollicis longus) crosses over the extensor carpi radialis longus and brevis tendons just beyond the Lister tubercle (22,23).

Figure 18. — Effigy 18. Normal appearance of the distal forearm in a 28-twelvemonth-former woman shows the site where intersection syndrome tin occur. Axial T1-weighted MR image shows the musculotendinous junction (white pointer) of the kickoff extensor tendons and the musculotendinous junction (black arrow) of the second compartment tendons. This is where proximal intersection syndrome tin occur. This is also delineated in the supplemental online Movie showing them crossing over each other.

In archetype (proximal) intersection syndrome, inflammation is thought to result from repeated flexion and/or extension at the wrist every bit seen in rowing, weightlifting, and occupational injuries. The pathophysiology is debated just probable includes a component of friction from apposition of the kickoff compartment myotendinous junctions on the second compartment tendons, as well as stenotic changes of the second compartment tendon sheaths (21,24,25). The main findings at MR imaging include tendon thickening, tenosynovitis, and peritendinous soft-tissue edema (21). Boosted findings can include muscle edema, soft-tissue edema, and tendinosis (increased intrasubstance signal intensity). Intravenous contrast agent assistants is not necessary to establish the diagnosis, only when administered demonstrates enhancement in the surface area of T2 hyperintensity and edema (26).

The diagnosis of intersection syndrome can too be accurately fabricated at US, which typically demonstrates hypoechoic tendon sheath fluid (tenosynovitis) as well as peritendinous edema (27). Hypervascularity can also be visible surrounding the tendons at Doppler imaging. These findings are singled-out from those seen in the chief clinical differential consideration, de Quervain tenosynovitis, on the basis of location (28).

Tenosynovial Giant Cell Tumor

Tenosynovial giant cell tumor (of which in that location is a localized and a diffuse class) is a mostly benign proliferative process. In the past, is has also been known as pigmented villonodular tenosynovitis (PVNTS) of the tendon sheath, localized or focal nodular synovitis, or behemothic prison cell tumor of the tendon sheath. The currently right World Wellness Organisation terminology is tenosynovial giant jail cell tumor, either localized or diffuse (29). Histologically, this is the same process, also previously known as pigmented villonodular synovitis (both local and diffuse forms), which tin occur intraarticularly (thirty).

Although uncommon overall, the hand and wrist area is i of the more mutual locations for tenosynovial giant cell tumor to occur. This is the second most common soft-tissue mass in the hand and wrist, second only to the mutual ganglionic cyst (30).

At MR imaging, tenosynovial behemothic cell tumor appears every bit a focal mass, often adjacent to or surrounding a tendon. Information technology is usually of intermediate or low T1 and T2 signal intensity and will enhance with dissimilarity medium administration. Heterogeneous high T1 and T2 bespeak intensity can also be seen in these lesions. If in that location is enough hemosiderin deposition within the mass, it can show blooming on gradient-repeat MR images (xxx,31).

Figure 19 shows a more diffuse grade of tenosynovial giant cell tumor extending along the dorsum of the wrist, deep to the extensor tendons. Information technology can as well appear equally a more discrete focal mass.

Figure 19a. Tenosynovial giant prison cell tumor in a 45-year-old man that was proven at pathologic analysis. This is the more diffuse grade, which extends along the dorsum of the wrist. **(a)** Axial T1-weighted MR image shows the lobulated mass (arrows) diffusely extending deep to the extensor tendons. Information technology is of intermediate signal intensity. The tendons appear normal. **(b)** Centric T2-weighted fat-saturated MR epitome shows the lobulated mass (arrows) to exist slightly hyperintense. Most of the mass was removed surgically, only not all, due to its insinuating nature.

Figure 19b. Tenosynovial behemothic jail cell tumor in a 45-year-sometime human being that was proven at pathologic analysis. This is the more lengthened grade, which extends along the dorsum of the wrist. **(a)** Axial T1-weighted MR image shows the lobulated mass (arrows) diffusely extending deep to the extensor tendons. It is of intermediate betoken intensity. The tendons announced normal. **(b)** Axial T2-weighted fat-saturated MR epitome shows the lobulated mass (arrows) to exist slightly hyperintense. Virtually of the mass was removed surgically, but non all, due to its insinuating nature.

At Us, tenosynovial behemothic cell tumor appears well-nigh often as a homogeneous hypoechoic mass adjacent to a tendon. The adjacent tendon is unremarkably normal in appearance. At that place is frequently internal vascularity visible at Doppler imaging (32). Figure 20 shows a more focal course of tenosynovial giant cell tumor surrounding the 2nd compartment tendon, extensor carpi radialis longus. The focal hypoechoic mass surrounds the normal tendon, and there is internal vascularity elucidated at ability Doppler imaging.

Figure 20a. — Effigy 20a. Tenosynovial behemothic cell tumor in a 56-twelvemonth-old woman. Transverse **(a)** and longitudinal color Doppler **(b)** US images show a focal ovoid hypoechoic mass (arrows) surrounding the normal extensor carpi radialis tendon (*). The mass surrounds the tendon and has areas of vascularity visible on the Doppler US prototype.

Figure 20b. Tenosynovial giant cell tumor in a 56-year-old woman. Transverse **(a)** and longitudinal color Doppler **(b)** US images bear witness a focal ovoid hypoechoic mass (arrows) surrounding the normal extensor carpi radialis tendon (*). The mass surrounds the tendon and has areas of vascularity visible on the Doppler United states of america image.

Although tenosynovial giant cell tumor is mostly a benign proliferative process, rare aggressive and/or malignant forms of tenosynovial giant jail cell tumor accept been reported (29).

Fibroma of the Tendon Sheath

A fibroma is another proliferative entity worth mentioning, although it is uncommon. Fibromas are benign proliferative lesions formed from spindle cells and collagen fibers. Information technology occurs adjacent to tendon sheaths every bit does PVNTS, and it can mimic the appearance of PVNTS. As there is a great deal of imaging similarity between both of these entities, a pathologic diagnosis is often needed to differentiate between the two entities, although gradient-echo susceptibility artifact, which is often nowadays with PVNTS, is absent-minded in fibromas, which tin be an important diagnostic clue (33).

At MR imaging, fibromas accept a variable appearance at T1- and T2-weighted sequences, ofttimes similar in intensity to skeletal muscle, although as in our instance (Fig 21) they tin prove areas of T2 hyperintensity. Morphologically they are ovoid well-encapsulated masses. They tend to show fiddling or no enhancement when gadolinium contrast medium is used. Although they are benign, they may exist symptomatic and are thus excised (34).

Figure 21a. — Effigy 21a. Fibroma adjacent to the fourth flexor tendon in a 21-year-quondam adult female, which was proven at pathologic assay. The mass was interfering with her ability to flex her finger, and, when removed, was found to exist adherent to the quaternary flexor digitorum profundus and the sheath of the flexor digitorum superficialis tendon. Axial **(a)** and sagittal **(b)** T2-weighted fatty-saturated MR images, just distal to the carpal tunnel, show a focal hyperintense mass (arrow), with areas of intermediate linear bespeak intensity. The mass is adjacent to the flexor tendon.

Figure 21b. — Effigy 21b. Fibroma adjacent to the fourth flexor tendon in a 21-year-quondam woman, which was proven at pathologic assay. The mass was interfering with her ability to flex her finger, and, when removed, was found to be adherent to the fourth flexor digitorum profundus and the sheath of the flexor digitorum superficialis tendon. Axial **(a)** and sagittal **(b)** T2-weighted fat-saturated MR images, just distal to the carpal tunnel, show a focal hyperintense mass (arrow), with areas of intermediate linear signal intensity. The mass is side by side to the flexor tendon.

Determination

Both MR imaging and US are excellent modalities for imaging wrist pathologic conditions. The states tin offer fast and relatively inexpensive evaluation of many pathologic atmospheric condition in comparison with the more expensive and time-consuming MR imaging. United states has the added benefit of enabling the sonographer to perform a focused examination on the area of concern and achieve first-class resolution with the probe often right over the area of business. MR imaging is better for big-motion-picture show views of the wrist and also evaluation of the adjacent bones and cartilage, which are partially or completely obscured at US.

There are multiple conditions that can afflict the tendons virtually the wrist. We have discussed and shown examples of many of these common conditions. In daily practise, tendinosis and tenosynovitis are the entities nigh likely to be encountered and can be seen in patients with inflammatory arthropathy or overuse syndromes. Tears and injuries to the tendons are hands imaged at either MR imaging or US. Calcific tendinopathy (calcium hydroxyapatite deposition) is not as mutual in the wrist, simply tin clinically mimic infection; imaging tin help to arrive at the right diagnosis and treatment. Masses adjacent to the tendons are rare, just information technology is still important to know the more common of these rare entities and exist able to diagnose them.

Disclosures of Conflicts of Involvement.— Srihari Sampath: Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: employment by the Novartis Research Foundation. Other activities: disclosed no relevant relationships. Srinath Sampath: Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: employment by the Novartis Research Foundation. Other activities: disclosed no relevant relationships.

For this journal-based SA-CME activeness, the authors Srihari Sampath and Srinath Sampath have provided disclosures (see "Disclosures of Conflicts of Interest"); all other authors, the editor, and the reviewers take disclosed no relevant relationships.

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Received: Feb x 2016
Revision requested: Mar vii 2016
Revision received: Apr 18 2016
Accepted: May 19 2016
Published online: Oct eleven 2016
Published in print: Oct 2016

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Source: https://pubs.rsna.org/doi/full/10.1148/rg.2016160014