Fig. 1
Coronal CT showing the 22G needle in articulation so that the solution composed of 2–3 ml of soluble contrast and 10–20 ml of filtered sterile air can be injected
The fluoroscopic monitoring is not required throughout the entire injection, and can be stopped after seeing that the needle is well positioned. It is not recommendable to inject much contrast in the shoulder because it may cause an extravasation especially at the level of the subscapularis recess. The images are acquired with the arm in neutral position or slight internal rotation, then they are reconstructed in coronal, sagittal, and oblique sagittal planes. In recent years, another acquisition in ABER position has been added (abduction 90° and maximum external rotation), as in arthro-MRI. The patient places the palm of his hand under his head turning the shoulder externally; this position determines the contact between the deep surface of the rotator cuff and the postero-superior portion of the glenoid labrum.
CT and CT Arthrography (CTA) in the Evaluation of Cuff Tears (Fig. 2a, b)
Fig. 2
Computed arthrotomography shows the humeral head and glenoid region of the scapula and soft tissue structures. Axial (a) and coronal (b) views. Distension of the glenohumeral joint allows identification of glenohumeral ligaments and sites of capsular insertion. The anterior capsular insertion varies somewhat in appearance: the capsule may insert in or near the labrum (type 1), medially or more medially along the scapular neck (types 2 or 3). Accurate analysis of glenoid labrum; variations in labral morphology (sublabral foramen and Buford complex) or tears. Evaluation of coracoacromial arch. Acromion shapes. Evaluation of long head biceps tendon. Evaluation of rotator cuff tear
The evaluation of the rotator cuff tendons by arthro-CT is considered a secondary instrumental examination, although the use of multidetector scanners with very thin volumes of acquisition and multiplanar reconstructions on three floors allows a good evaluation of cuff tendons.
The arthro-CT has shown a good sensitivity in the diagnosis of rotator cuff ruptures. The tears of the articular surface of the tendon can be diagnosed by recognizing the contrast agent inside the rotator cuff, but through it without a full thickness or by detection of a small lesion on the surface of synovial bag. Also the intratendinous rotator cuff lesions can be showed with the arthro-CT, but only if they communicate with the joint cavity. The lesions, which do not communicate, and the partial lesions of the bursal surface cannot be viewed with this method. Intrabursal subdeltoid/subacromial injection has minimum efficiency in the study of partial lesions of the tendon bursal surface by displaying accumulation of contrast agent in the lesion of the tendon.
The sensitivity and specificity of CT are comparable to those of MR, especially if CT is performed with intra-articular injection of the contrast agent. CT arthrography showed a sensitivity of 99 % and a specificity of 100 % in the diagnosis of tears of supraspinatus. As for infraspinatus tears, these figures were 97.44 % and 99.52 %, respectively; as for subscapularis, 64.71 and 98.17 %. In case of lesions of the long head of the biceps, the sensitivity was 45.76 % and the specificity was 99.57 % [1].
CT allows the same evaluations performed by MRI in case of rotator cuff lesions, yet the capacity to discriminate the different tissues is much lower due to the poorer resolution of CT with respect to MRI, the latter being the gold-standard method in the evaluation and classification of cuff lesions.
With such limitations, CT allows to evaluate:
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The location of the tendon lesions, in particular by CTA. The location influences the choice of the treatment to follow. CT allows to discriminate efficiently a lesion of the insertion footprint from a lesion in a critical location or in other regions. In addition, yet less efficiently in comparison to MR, it is possible to detect partial lesions, especially on the articular side, which appear clearly in presence of the contrast agent (Fig. 3).
Fig. 3
Coronal CT arthrogram showing partial-thickness articular surface tear of supraspinatus tendon in a patient affected by glenohumeral arthritis. The deep fibers of the tendon are interrupted, but not retracted, and this explains the linear (contrast-white) appearance of the tear. This lesion communicates with the joint. Tears of bursal surface of the supraspinatus tendon cannot be examined at arthro-CT, which permits opacification only of the joint surfaceRelated posts:
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