Although the best imaging tool for rotator cuff partial-thickness tear is MRA, CTA could provide a comparable diagnostic performance particularly in articular surface partial-thickness tear; CTA is an alternative tool when MRA could not be performed for any reason, the inherent high resolution of CTA and high image contrast allows for detection of small tendinous tear. However, CTA alone without subacromial bursography could not characterize the extent of the tear regarding its percentage of fiber affection, in relation to the entire tendon thickness, which could be a significant imaging finding that affect further management. Furthermore, CTA only without subacromial bursography could not detect bursal surface tear; hence, the current study chose the utilization of combined intra-articular and intra-bursal contrast injection to enhance the diagnostic performance of CTA of the shoulder not only in detection but also in characterization of rotator cuff tears [4, 5].
The current study characterized both type and size of RCTs. Regarding detection of various types of rotator cuff tear, combined CTA and bursography in the study were able to detect all types of tear based on violated surface; this included pure bursal surface tear which could not be detected if CTA was performed alone. Fermand et al. and Faure et al. [6, 7] studied subacromial CT bursography in patients with a partial surface tear of the rotator cuff tendon. They reported that bursography was able to detect bursal surface irregularities, defect or frank tear; their results were expected as they highlighted the bursal surface of the rotator cuff, so that any superficial surface tear or irregularity would be detected; however, they did not able to assess for tendon thinning or measure accurately the thickness involved by tear, and this would be attributed to diagnostic limitation of CT bursography if performed individually without concurrent CTA [6, 7].
Regarding the direction-based assessment of tear type, the current study was able to differentiate simple tear from multi-directional one; this is aided by the inherent contrast between the low attenuation tendon and the injected intra-articular contrast medium, also the low attenuation of the tendon is generally not affected by the injected contrast, so there are no specific considerations on assessment of tear morphology, this appears to be different from MRA in which contrast medium can be imbibed by the adjacent tendinopathy or frayed friable tendon margins and therefore assessment of tear on T1 fat-suppressed images only could reveal inaccurate results, and thus T1 fat-suppressed images must be assessed alongside fluid sensitive images [8].
Regarding tear size and its mediolateral extension, the study followed the same way described by Thomazeau et al. [9], who described full-thickness rotator cuff tear on arthroscopy and categorized it, in relation to anatomic neck of the humerus, into distal, intermediate, and retracted (replaced by medial in our study). This easily correlated arthroscopically based method differentiates massive rotator cuff tears form non-massive ones; it could be helpful if become a part of the diagnostic checklist in pre-operative arthrographic reporting, as it provides an insight about the quality of the tendon, and thus plays an important role in planning and tailoring the repair technique as poor quality tendon can compromise usual arthroscopic rotator cuff fixation and may require specialized techniques. Detailed characterization of the RCTs on CTA by means of tendon tear size whether small or massive, presence or absence of interstitial extension within the remaining apparently spared tendon and the degree of affected thickness whether partial- or full-thickness would reduce the failure rate of rotator cuff repair that might occur in marked or massive tears [1, 9].
Regarding the percentage of affected thickness in the current study, most of partial-thickness tears in the study fall in either more than one-half or more than three-fourth thickness affection categories; some tears were so extensive, but still affect < 100% of tendon thickness. Tendon thickness affection is an important factor that should be reported on CTA; distinction between shallow and deep partial-thickness tear is necessary for pre-operative planning, as operative/arthroscopic repair of partial-thickness rotator cuff tear is indicated when more than three fourths of tendon thickness affection. Extensive partial-thickness tears sparing thin fibers (near full-thickness) are repaired by the same fashion as done in full-thickness ones. Charousset et al. [4] studied the accuracy of CTA in rotator cuff tear; they found different sensitivities and specificities for diagnosis of different rotator cuff tendon tears, although they found high sensitivity (99%) and specificity (100%) for diagnosis of supraspinatus tear, they did not characterize such tears, regarding their percentage of fiber affection. Oh et al. [10] assessed the effectiveness of CTA for diagnosis of rotator cuff disorders with arthroscopic correlation; they found high sensitivity (89%) and specificity (98%) in full-thickness tear; however, for partial-thickness rotator cuff tear, the sensitivity was very low (22%) with relatively high specificity (87%), this is could be attributed to poor sensitivity of CTA in bursal surface partial thickness tear. Omoumi et al. [2] studied the multidetector CT arthrography in evaluation of rotator cuff tears and compared them with 1.5-T MRA, although they found similar diagnostic performance of both techniques, CTA had lower sensitivity in partial-thickness supraspinatus tendon tears (60%). The distinction between different grades of thickness affection in partial thickness tear is allowed only when concurrent bursography is performed with CTA. To the best of the authors’ knowledge, all known studies that assessed the value of CTA in RCTs assessed its value in detection of RCTs, not in their characterization, they were not able to assess the percentage of tendon thickness affection, and this is the first article trying to study and highlight such a point, that would refine the CT arthrographic study when performed in the context of rotator cuff tear [2, 4, 10,11,12,13,14].
The sensitivity of CTA and concurrent sub-acromial bursography in detection of rotator cuff tears in arthroscopically treated patients was 100%, whereas the specificity was variable due to false positive results regarding the subscapularis and infraspinatus tendons, it was 100% for supraspinatus tendon tear, 83% for subscapularis tendon tears and 40% for infraspinatus tendon tear. Concerning infraspinatus tendon false positive results in our study; all of which demonstrated interstitial tear type which an was intra-substance extension from adjacent supraspinatus tear that resulted in infraspinatus fiber delamination, this type of tear could not be visible at arthroscopy and this might explain this high false positive rate on CTA and concurrent bursography for this tendon. Regarding the false positive rate in subscapularis tendon, it could be attributed to technical difficulty to asses it at arthroscopy compared with the supraspinatus and infraspinatus tendons [2, 15, 16].
The current study has low complication rates, the percentage of extra-articular contrast injection at the site of needle path was low, and its effect was minimal without image interpretation difficulties; this could be due to injecting the contrast in real-time fashion using ultrasonographic guidance which allowed for accurate needle localization and proper targeted injection. There were some cases demonstrated extra-articular contrast leaks from the subscapular recess into the subscapularis muscle and from the biceps synovium, although there was no increased resistance experienced during contrast injection. Such unexplained findings might be related to associated capsulitis with subsequent weakness of the joint capsule. Ogul et al. [17] studied the extra-articular contrast material leakage within sites unrelated to the injection path in shoulder MRA, they observed three sites of contrast material leakage at subscapular recess, the synovium of the biceps and the axillary recess, they found that the amount of extravasation was significantly higher in patients with adhesive capsulitis compared with patients with different diagnosis, and the most frequently associated shoulder pathology with extravasation was superior labrum anterior-posterior (SLAP) lesion [17].