How effective is ultrasound (ultrasonography) in diagnosing calcific tendinosis and is it beneficial to use X-ray (radiography) in conjunction with it?

Ultrasound Performance in Diagnosing Calcific Tendinosis

Both ultrasound and X-ray (conventional radiography) are recommended imaging modalities for diagnosing calcific tendinosis, and using them together provides complementary information that optimizes diagnostic accuracy. 1

Ultrasound Diagnostic Capabilities

Ultrasound is highly effective at detecting calcific tendinosis and offers several distinct advantages:

• Ultrasound allows precise localization of calcium deposits within individual tendon components and periarticular structures, demonstrating superior spatial resolution for identifying the exact anatomic location of calcifications 1

• For patellar tendinopathy, ultrasound demonstrates high specificity (94%) but moderate sensitivity (58%), making it better at ruling in the diagnosis when positive rather than ruling it out when negative 1

• Ultrasound can identify characteristic findings including tendon thickening, decreased echogenicity (hypoechoic appearance), heterogeneous echotexture, and the calcific deposits themselves 1

• Ultrasound detects inflammation and soft tissue changes that accompany calcific tendinosis, including increased color Doppler signal indicating hyperemia and surrounding soft tissue edema 2

• Ultrasound is particularly valuable during the resorptive phase when calcium deposits may migrate into neighboring tissues (bursal, intraosseous, or muscular migration), causing severe pain and diagnostic confusion 3, 4

X-ray Diagnostic Capabilities

Conventional radiography provides complementary but different information:

• X-rays can demonstrate calcific tendinosis and provide comprehensive information about the joint as a whole, including associated bony abnormalities 1

• Plain radiography may show calcific tendinosis, calcaneal avulsion fractures, and soft-tissue swelling in conditions like Achilles tendinopathy 1

• For rotator cuff pathology, plain radiography can reveal sclerosis, spur formation, or calcific tendinosis that may contribute to symptoms 1

• X-rays serve as an excellent screening tool and should typically be obtained first in most cases to exclude other pathology and provide baseline anatomic information 1

Why Both Modalities Together Are Optimal

The 2023 EULAR recommendations explicitly state that either conventional radiography OR ultrasound may be used for diagnosing basic calcium phosphate deposition (BCPD), with the choice depending mainly on availability 1. However, the evidence suggests using both provides superior diagnostic information:

• Ultrasound provides superior resolution for demonstrating smaller deposits and early disease, while certain anatomic areas lack adequate acoustic windows for ultrasound visualization 1

• X-rays provide comprehensive joint assessment and can identify calcifications that ultrasound might miss in areas with poor acoustic access 1

• The two modalities detect calcifications at different stages: X-rays are better for established, dense calcifications, while ultrasound excels at detecting softer calcium deposits during the resorptive phase when symptoms are most severe 4

Clinical Algorithm for Imaging Calcific Tendinosis

1. Start with plain radiographs as the initial screening tool to identify obvious calcifications and exclude other bony pathology 1

2. Add ultrasound when:

   • Radiographs are negative but clinical suspicion remains high 1
   • Precise localization of calcium deposits is needed for treatment planning 1
   • Assessment of surrounding soft tissue inflammation is required 2
   • The patient presents with acute severe pain suggesting resorptive phase with possible calcium migration 3, 4

3. Reserve MRI for:

   • Cases where diagnosis remains unclear after radiographs and ultrasound 1
   • Preoperative evaluation 1
   • When comprehensive assessment of associated tendon tears or other soft tissue pathology is needed 1

Important Caveats

• Ultrasound is operator-dependent, so diagnostic accuracy varies with sonographer experience 1

• During the resorptive phase, calcium may appear soft and migrate to unexpected locations (bursa, bone, muscle), potentially mimicking other pathologies like infection or tumor 3, 4

• Plain radiographs may remain negative depending on timing, calcium density, and anatomic location of the deposit 1

• Ultrasound cannot adequately visualize certain deep structures like menisci or articular discs due to lack of acoustic windows 1