**4.3 De Quervain tenosynovitis**

It is the second most common stenosing synovitis, presenting with pain and swelling at the styloid process region when moving the thumb or wrist. Anatomically, the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendons are held within a fibro-osseous sheath called the extensor retinaculum. Repetitive trauma results in thickening of the tendons and retinaculum resulting in inflammation and edema. In some cases, a septum has been found between both tendons, thought to worsen symptoms.

On US, the APL and EPB tendons are thickened at the level of the radial styloid with increased fluid within the first extensor compartment. A halo sign has been described, secondary to peritendinous subcutaneous edema. Doppler imaging should show increased vascularity secondary to hyperemia and inflammation [15].

### **Figure 3.**

*On the left side, we have a T2WI showing the tendon as a hypointense structure; while on the right side we see a composite US image of the flexor tendon of the finger with some areas of anisotropy.*

On MRI, tenosynovitis is seen as increased signal intensity on T2WI and low to intermediate signal on T1WI of the tendon sheath. The retinaculum will also appear thickened with increased T2 signal intensity. When the tendon is thickened, mostly seen at the radial styloid at its medial aspect, with increased T1 and T2 intra-tendinous signal and a striated tendinous signal, tendinosis is said to be present. These may also be accompanied by a longitudinal tendinous tear, where linear T2 signal will be seen traversing the tendon, most common in the APL, due to fluid within the tendinous rupture.

### **4.4 Flexor tendon/trigger finger**

Trigger finger is a stenosing tenosynovitis secondary to repetitive microtrauma. This results in inflammation and thickening of the flexor tendon and tendon sheath, causing transient locking of the digit in a flexed position.

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ing an effusion [16].

**5.1 MRI protocol**

**5.2 Ultrasound examination technique**

**5. Knee**

**Figure 4.**

*finger".*

*Imaging of Tendons*

*DOI: http://dx.doi.org/10.5772/intechopen.84521*

This pathology is mainly evaluated with US instead of MRI (**Figure 4**). On US, the flexor tendon and A1 pulley will be thickened with a diameter greater than 1.1 mm. Hypoechoic fluid may also be seen around the tendon sheath, represent-

*Thickening of the A1 pulley in the 3rd flexor tendon of the hand consistent with clinical picture of "trigger* 

The knee is positioned in a relaxed state, with about 5° of external rotation so that the anterior cruciate ligament is orthogonal to the sagittal plane of imaging. A small field of view is used, usually between 14 and 16 cm, and multiplanar imaging is obtained with coronal, sagittal, and axial images [17]. Sequences of a knee MRI should include any combination of fluid-sensitive sequences with anatomic sequences. Fluidsensitive images can be either fat-sat PDW, or T2W spin-echo images versus STIR images. Anatomic sequences may include either T1W or PDW, spin-echo images [18].

Ultrasound evaluation may be completed with the patient supine, although the posterior structures are better seen in the prone position [19]. Examination may be

### **Figure 4.**

*Tendons*

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tendinous rupture.

**Figure 3.**

**4.4 Flexor tendon/trigger finger**

On MRI, tenosynovitis is seen as increased signal intensity on T2WI and low to intermediate signal on T1WI of the tendon sheath. The retinaculum will also appear thickened with increased T2 signal intensity. When the tendon is thickened, mostly seen at the radial styloid at its medial aspect, with increased T1 and T2 intra-tendinous signal and a striated tendinous signal, tendinosis is said to be present. These may also be accompanied by a longitudinal tendinous tear, where linear T2 signal will be seen traversing the tendon, most common in the APL, due to fluid within the

*On the left side, we have a T2WI showing the tendon as a hypointense structure; while on the right side we see a* 

*composite US image of the flexor tendon of the finger with some areas of anisotropy.*

Trigger finger is a stenosing tenosynovitis secondary to repetitive microtrauma. This results in inflammation and thickening of the flexor tendon and tendon sheath, causing transient locking of the digit in a flexed position.

*Thickening of the A1 pulley in the 3rd flexor tendon of the hand consistent with clinical picture of "trigger finger".*

This pathology is mainly evaluated with US instead of MRI (**Figure 4**). On US, the flexor tendon and A1 pulley will be thickened with a diameter greater than 1.1 mm. Hypoechoic fluid may also be seen around the tendon sheath, representing an effusion [16].

### **5. Knee**

### **5.1 MRI protocol**

The knee is positioned in a relaxed state, with about 5° of external rotation so that the anterior cruciate ligament is orthogonal to the sagittal plane of imaging. A small field of view is used, usually between 14 and 16 cm, and multiplanar imaging is obtained with coronal, sagittal, and axial images [17]. Sequences of a knee MRI should include any combination of fluid-sensitive sequences with anatomic sequences. Fluidsensitive images can be either fat-sat PDW, or T2W spin-echo images versus STIR images. Anatomic sequences may include either T1W or PDW, spin-echo images [18].

### **5.2 Ultrasound examination technique**

Ultrasound evaluation may be completed with the patient supine, although the posterior structures are better seen in the prone position [19]. Examination may be focused over the area that is relevant to the patient's history; nonetheless a complete examination of all areas should be performed. Sonographic examination may be divided in four methods: anterior, medial, lateral, and posterior evaluation of the knee.


### **5.3 Patellar tendon**

The patellar tendon is part of the extensor mechanism of the knee, which originates at the patellar apex and inserts at the tibial tuberosity. It is located anteriorly to Hoffa's fat pad, and is usually about half of the thickness of the quadriceps

**25**

bursal fluid.

**Figure 5.**

**6. Hip joint**

**6.1 MRI protocol**

*Imaging of Tendons*

*DOI: http://dx.doi.org/10.5772/intechopen.84521*

tendon (approximately 0.5 cm), as seen on sagittal MRI with low homogeneous signal in all sequences (**Figure 5**) [18]. When visualizing it with ultrasound, the patellar tendon should normally exhibit an echogenic, fibrillar appearance. Deep to the tendon, Hoffa's fat pad appears hyperechoic or isoechoic to muscle. The region around the distal patellar tendon is also evaluated for infrapatellar

*Quadriceps and patellar tendons showing the dark signal qualities on PDWI.*

Focal patellar tendinosis of the proximal deep insertional fibers is termed jumper's knee in adults, usually presenting as pain in the inferior patellar region. It is often visualized on MRI as thickening of the proximal patellar tendon with increased signal on T2W images [21]. A similar finding in children (often associated with cerebral palsy) is known as Sinding-Larsen-Johansson disease. A complete rupture of the tendon is usually easily identified, due to the secondary finding of a patella alta. Ultrasound can be very useful in the evaluation of tendinosis and partial tears. Tendinosis will appear as focal or diffuse hypoechogenicity and thickening of the tendon. Partial-thickness tear may reveal similar findings with possible anechoic interstitial clefts. Marked hyperemia from neovascularity may also be identified with color Doppler imaging [22]. Full-thickness tears are seen as complete tendon fiber discontinuity and refraction shadowing at the retracted torn tendon stumps [20].

MRI evaluation of the hip is performed while the patient is in the supine position. Coronal, axial, sagittal and axial oblique planes are obtained for

focused over the area that is relevant to the patient's history; nonetheless a complete examination of all areas should be performed. Sonographic examination may be divided in four methods: anterior, medial, lateral, and posterior evaluation of the knee.

1.Anterior knee: Evaluated with patient in a supine position and knee slightly flexed 20–30°. The primary structures evaluated in this approach include the quadriceps tendon, patella, patellar tendon, patellar retinaculum, suprapatellar joint recess, the medial and lateral recesses, and the anterior knee bursae [20]. Evaluation begins with transducer in the sagittal plane, proximal to the patella, to evaluate the quadriceps tendon. Deep to the quadriceps tendon, the suprapatellar recess is identified. Next, the transducer is moved inferiorly in the sagittal plane to evaluate the patellar tendon. The transducer is then moved to both the medial and lateral margins of the patella in the transverse plane, to evaluate the medial and lateral patellar retinacula, and the underlying medial and lateral recesses. Finally, the knee is placed in a 90° flexed position to evaluate the femoral trochlear cartilage in the transverse plane superior to the patella.

2.Medial knee tendons: The patient remains supine and rotates hip externally for evaluation of the medial aspect of the knee. The tendinous structures that are

3.Lateral knee: The patient is in supine position, with internal rotation of the hip, and knee slightly flexed. The key structures that are examined include the iliotibial band, lateral collateral ligament (LCL), biceps femoris tendon, popliteus, common peroneal nerve, and body and anterior horn of the lateral meniscus [19]. The transducer may be initially placed over the long axis of the patellar tendon, and then moved laterally to identify the iliotibial band. Next, the transducer is moved laterally to the coronal plane over the lateral femoral condyle to identify the groove for the popliteal tendon, an important bone landmark. Using this groove as a landmark, the proximal end of the transducer is stabilized on the femur, and the distal aspect is rotated posterior to visualize the fibular head. At this site, LCL is identified. After the transducer is moved along the LCL to its fibular attachment, the distal end of the transducer is anchored to the fibular head while the proximal aspect is rotated posteriorly in the coronal plane to visualize the biceps femoris tendon. As the transducer is moved posteriorly from the coronal plane view, the common peroneal nerve can be identified. Upon return to the popliteal groove, the distal popliteal tendon may be followed.

4.Posterior knee: The posterior aspect of the knee is evaluated with the patient in prone position and extended knee. The structures that may be identified are the posterior horns of the menisci, posterior cruciate ligament, the popliteal neurovascular bundle, and the presence of a Baker cyst [20]. The transducer is placed in the transverse plane of the mid-calf to identify the deep soleus and medial and lateral heads of the gastrocnemius muscles. The medial head of the gastrocnemius is followed proximally until the semimembranosus tendon is identified medially. If a Baker cyst is present, it will be visualized between these two structures.

The patellar tendon is part of the extensor mechanism of the knee, which originates at the patellar apex and inserts at the tibial tuberosity. It is located anteriorly to Hoffa's fat pad, and is usually about half of the thickness of the quadriceps

evaluated in this region are the pes anserine tendons [19].

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**5.3 Patellar tendon**

**Figure 5.** *Quadriceps and patellar tendons showing the dark signal qualities on PDWI.*

tendon (approximately 0.5 cm), as seen on sagittal MRI with low homogeneous signal in all sequences (**Figure 5**) [18]. When visualizing it with ultrasound, the patellar tendon should normally exhibit an echogenic, fibrillar appearance. Deep to the tendon, Hoffa's fat pad appears hyperechoic or isoechoic to muscle. The region around the distal patellar tendon is also evaluated for infrapatellar bursal fluid.

Focal patellar tendinosis of the proximal deep insertional fibers is termed jumper's knee in adults, usually presenting as pain in the inferior patellar region. It is often visualized on MRI as thickening of the proximal patellar tendon with increased signal on T2W images [21]. A similar finding in children (often associated with cerebral palsy) is known as Sinding-Larsen-Johansson disease. A complete rupture of the tendon is usually easily identified, due to the secondary finding of a patella alta.

Ultrasound can be very useful in the evaluation of tendinosis and partial tears. Tendinosis will appear as focal or diffuse hypoechogenicity and thickening of the tendon. Partial-thickness tear may reveal similar findings with possible anechoic interstitial clefts. Marked hyperemia from neovascularity may also be identified with color Doppler imaging [22]. Full-thickness tears are seen as complete tendon fiber discontinuity and refraction shadowing at the retracted torn tendon stumps [20].
