Comparative study of Ultrasound and MRI in diagnosis and assessment of shoulder impingement syndrome

INTRODUCTION

The third most prevalent source of musculoskeletal discomfort is the shoulder joint, which affects 7–26% of the general population.¹

Adults had a 2.4 percent annual prevalence and 1.5 percent annual incidence of shoulder disorders, respectively.²

Shoulder discomfort is frequently caused by rotator cuff disease.³

Repetitive action at or above the shoulder level, such as work or leisure activities, causes shoulder impingement syndrome.⁴

Shoulder impingement syndrome is more common in those over the age of 40, thus age is another aspect to consider.⁵

Inflammation or degeneration of the tendons or bursae, dysfunctional glenohumeral and scapulothoracic mechanics, debilitated rotator cuff or scapular musculature, joint capsule abnormalities, positional disorders of the neck or shoulder, and structural deformities of the pertinent skeletal components.⁶

A multitude of factors can lead to shoulder impingement syndrome. They are split into two categories: structural variables and functional factors.⁷

The distance between the coracohumeral curve above and the humeral head and tuberosities below is the cause of shoulder impingement syndrome. The rotator cuff tendons travel via this area.⁸

Subacromial impingement, subcoracoid impingement, and internal impingement are the three different types of impingement in the shoulder.⁹

In the general population, the most prevalent reason of shoulder discomfort is subacromial impingement, which accounts for 44–65 percent among all shoulder disorders.¹⁰

Shoulder impingement syndrome is frequently accompanied by a partial or total tear of the rotator cuff tendon, necessitating examination of rotator cuff integrity in these individuals.¹¹

Non-contrast MRI is the best imaging modality for individuals with suspected shoulder impingement.¹²

Although MRI was thought to be a reliable tool for evaluating tendons of rotator cuff muscles, it just evaluates the shoulder joint in a static state. Because most signs are nonspecific, it can only imply a diagnosis of subacromial impingement indirectly.¹³

The limited availability of open MR and the fact that MR imaging can only image single-plane shoulder movements sequentially that do not fully mimic physiologic movements of the shoulder are the two primary limitations of dynamic MRI.¹³

Being a widely available, non-invasive, and fast tool for musculoskeletal issues, particularly those involving the shoulder joint. The use of high-resolution ultrasonography as a diagnostic tool for musculoskeletal assessment is becoming more common.¹³

PATIENTS AND METHODS

Our study was carried out on 50 patients diagnosed clinically with a subacromial impingement in the radiology department of El Hussein and Sayed Galal hospitalsFrom March 2021 to September 2021.

The patients were selected using a set of criteria for inclusion and exclusion.

The study included patients with age range (20 – 60 years), pain at the shoulder for more than 3 months, and positive clinical tests.

We exclude patients with a history of surgical procedure on the shoulder, previous shoulder dislocation, history of fracture of the shoulder girdle and neoplastic lesions, and congenital anomalies.

The following was done to all of the patients:

Obtaining a medical history and making a clinical preliminary diagnosis.

Radiological investigations: Static & dynamic ultrasound and Conventional MRI.

Complete standard sonographic assessment of shoulder joint was performed to characterize the etiology & sequel of subacromial impingement as well as any associated abnormality. All of the cases were also subjected to a dynamic sonographic examination.

The patients were instructed to do the active movement once more for a few occasions during the examination. The results obtained by Sonographic examination were correlated to the results obtained by MR examination.

The patients were examined using a Toshiba ultrasound device (Aplio 500) electric that has been fitted with a linear array probe with a frequency band of 5–12 MHz for musculoskeletal applications to identify the causes of painful shoulder and/or shoulder movement limitations, as well as any other abnormalities that may be present.

The technique of examination:A little patient's medical history should be gathered before beginning the examination, as this can be highly crucial in assessing if the referrer's request and subsequent imaging findings correspond to a definitive diagnosis of the underlying condition.

While the patient is resting, an ultrasound examination is performed. The operator may sit in front of or behind the patient. The scan should be carried out in a position that is both technically and physically suitable. The operator's shoulder should be raised above the shoulder level of the patient.

The biceps tendon's long head is assessed first, with the forearm of the patient on or above the ipsilateral thigh. The palm is pointing upward and the elbow is bent at a 90-degree angle. The probe is moved craniocaudally from the sulcus bicipitalis to the myotendinous junction to determine the length of the tendon.

After that, by 90-degree rotation of the probe to observe the tendon's length, the tendon's long-axis view is obtained. The tendon's continuity, tendinopathy, tendon sheath effusion, and synovitis are all evaluated.

Biceps Tendon Long Head and Subscapularis Tendon dynamic Examination: The probe placed in the axial direction over the anterior shoulder in the same place as the bicipital sulcus to see the tendon from a long-axis perspective. The patient's forearm is to be twisted laterally whilst maintaining the elbow close to the wall of the chest, since the tendon will be pulled out from beneath the coracoid process as a result of this, allowing inspection. By rotating the probe 90 degrees, a short-axis image is acquired, revealing its multipennate appearance, which includes hypoechoic fibers of the muscle, appears sandwiched between its hyperechoic fibers.

Rotator Interval and Supraspinatus tendon:

Starting over the rotator interval is the optimum option. The probe was placed with the long axis of the long head of the biceps tendon. The supraspinatus tendon runs in parallel to the long head of the biceps tendon and may be easily assessed by sliding the probe posteriorly across the greater tuberosity in the same plane as the longitudinal plane of the biceps tendon.

For assessment tendon of the supraspinatus muscle, the Crass and modified crass postures have been outlined. The dorsal side of the hand is positioned over the lumbar area on the ipsilateral side in the Crass position.

Place the probe on the shoulder's anterior side in a transverse plane. While retaining the upper arm in the modified crass posture to show the supraspinatus tendon in a short-axis perspective.

After that, with the upper limb in the same posture, the probe is rotated 90 degrees along the supraspinatus tendon's long axis to acquire a long axis image of the tendon. Tears, tendinopathy, and calcification are all looked for in the tendon.

Subacromial Bursa:It is a thin sac that lies in between deltoid muscle and the rotator cuff tendons, and it takes the form of a hypoechoic thin layer covering the rotator cuff. At the same time that the supraspinatus tendon is evaluated. It is checked for synovitis, thickening of the bursa, and effusion.

Tendons of the Infraspinatus and Teres Minor; and recess of the Glenohumeral Joint:With the palm facing up, return the hand to the thigh. The transducer is situated underneath and coplanar to the scapula's spine, giving a longitudinal view of the infraspinatus and teres minor tendons from their origin on the posterior greater tuberosity to their insertion. The glenohumeral joint's posterior recess can be assessed for effusion by moving the transducer medially on the same level. The infraspinatus muscle belly is well exhibited in its short axis in the infraspinatus area. It has central echogenicity in its tendon. Its echogenicity and size can be compared to the teres minor muscle to see if it has fatty degeneration or atrophy.

Acromioclavicular (AC) Joint:The probe is aligned in the coronal plane to evaluate it across the upper shoulder and distal clavicle. The clavicle and acromion's superior bony outlines are apparent since the joint capsule embraces the joint space and housing the fibrocartilage disc. The joint is examined for signs of swelling or constriction, uneven boundaries, capsular bulging, and synovitis.

The technique of Magnetic Resonance Imaging:

Devices: high field (1.5 Tesla) closed magnet unit (PHILIPS).

Patient position:The patient has to be flat with the head facing the scanner aperture. The preferred arm posture of the patient is to be neutral and turned slightly to the outside.

Surface coil(Flexible coil): wrap around the anatomical area of interest and conform to it.

Pulse sequences and imaging planes: Preliminary Scout Localizer in three planes: axial, sagittal, and coronal.

Coronal T1 (TSE, TR 664, TE 18, FOV 14, SL 4, MTARIX 205x512, NSA 3),

Coronal T2 (TSE, TR 2411, TE 100, FOV 14, SL 4, MTARIX 201x512, NSA 2),

Coronal STIR (TSE, TR 2411, TE 15, FOV 14, SL 4, MTARIX 201x512, NSA 2)

Axial GR (TSE, TR 551, TE 18, FOV 17, SL 4, MTARIX 179x512, NSA 3)

Sagittal T2 (TSE, TR 3342, TE 100, FOV 16, SL 4, MTARIX 205x512, NSA 3)

Selected cases                       

Case (1) Male patient 51 years old, complaining of right shoulder pain markedly limiting the shoulder movement, for 6 months duration. History of old trauma yet with no dislocation. No history of operation.

Fig. 1: ultrasonography shows full thickness tear of supraspinatus tendon, with muscle retraction & excessive effusion filling the gap.

Fig. 2:Conventional MRI coronal T2 WIs (Figure 2) of the same case shows discontinuity of the supraspinatus tendon with muscle belly retraction & gapping filled with fluid.

Case (2):- Male patient 56y presented with right shoulder pain of 4 months duration with limitation of arm elevation. No history of trauma, dislocation, or operation.

Fig. 3: Ultrasonography shows a focal hypoechoic area within the supraspinatus tendon not involving the whole thickness of tendon, representing partial interstitial tear.

Fig. 4: Ultrasonography shows thickened long head of biceps tendon with fluid around it (tenosynovitis of the long head of biceps tendon)

Fig.5 : Conventional MRI, coronal T2 WI of the same case shows a focal small area of bright T2 signal intensity at the supraspinatus tendon, not reaching the articular or bursal surface, representing partial interstitial tear

Fig. 6: Conventional MRI, coronal & axial T2 WIs of the same case shows a focal small area of bright T2 signal intensity (Figure 5) at the supraspinatus tendon, not reaching the articular or bursal surface, representing partial interstitial tear  as well as fluid signal encircling the long head of biceps tendon (Figure 6) representing tenosynovitis.

RESULTS

Table1: The percentage and frequency in accordance with sex

Table 2: The incidence of various pathological injuries based on the average age (40 years)

Table 3: The frequency of shoulder side affection, as well as the percentage of people that have it.

Table (4): The frequency and percentage of different pathological findings detected by ultrasonography

Table 5: The frequency and percentage of different pathological findings detected by conventional MRI

Table 6: Comparing the capability of dynamic ultrasonography in detection of different pathological lesions compared to conventional MRI

Table 7: Sensitivity, Specificity, PPV, and NPV of dynamic ultrasonography compared to conventional MRI in the detection of different pathological lesions encountered in shoulder impingement