Musculoskeletal Imaging Original Research

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1 MR rthrography fter Rotator Cuff Repair Musculoskeletal Imaging Original Research C M E D E N T U R I C L I M G I N G JR 2006; 186: X/06/ merican Roentgen Ray Society Y Sylvain R. Duc 1 ernard Mengiardi 1 Christian W.. Pfirrmann 1 ernhard Jost 2 Juerg Hodler 1 Marco Zanetti 1 O F Keywords: joint, MR arthrography, MRI, musculoskeletal imaging, orthopedic surgery, shoulder DOI: /JR Received November 24, 2004; accepted after revision January 12, Department of Radiology, University Hospital algrist, Forchstrasse 340, Zurich CH-8008, Switzerland. ddress correspondence to S. R. Duc (sylvain.duc@balgrist.ch). 2 Department of Orthopedic, University Hospital algrist, Zurich CH-8008, Switzerland. Diagnostic Performance of MR rthrography fter Rotator Cuff Repair OJECTIVE. The objective of this study was to investigate the diagnostic performance of MR arthrography after rotator cuff repair. MTERILS ND METHODS. MR arthrographic examinations of the shoulder performed after rotator cuff repair and before revision surgery were retrospectively analyzed in 48 patients (31 males, 17 females; mean age, 50.3 years; age range, years). Full-thickness and partial-thickness defects of the supraspinatus, infraspinatus, and subscapularis tendons were diagnosed independently by two radiologists. Revision surgery served as the standard of reference. RESULTS. correctly recognized five of eight intact supraspinatus tendons, 10 of 19 partial-thickness defects, and 19 of 21 full-thickness defects. For observer 2, the numbers were three of eight, eight of 19, and 18 of 21. The corresponding numbers for the infraspinatus tendon for observer 1 were 28 of 31, 0 of three, and 14 of 14 tendons. For observer 2, they were 28 of 31, two of three, and 11 of 14. For the subscapularis tendon, observer 1 made the correct diagnosis in 18 of 31, five of six, and nine of 11 tendons. The results for observer 2 were 26 of 31, one of six, and 10 of 11 tendons. Interobserver agreement (weighted κ) was 0.47 for the supraspinatus, 0.64 for the infraspinatus, and 0.20 for the subscapularis tendons, respectively. CONCLUSION. Postoperative full-thickness defects of the rotator cuff are reliably diagnosed with MR arthrography. The diagnostic performance for partial-thickness defects is only moderate. ull-thickness defects of previously repaired rotator cuff tears F can be diagnosed with an accuracy of 83 90% on standard MR images [1, 2]. Differentiation of partial-thickness defects of the rotator cuff tendons from clinically irrelevant postoperative distortion and thinning of tendons is more difficult. The reported diagnostic performance of MRI has been variable [1, 2]. In shoulders that have not undergone surgery, MR arthrography improves the accuracy for detection of supraspinatus [3] and subscapularis [4] abnormalities when compared with standard MRI. This method may also be worthwhile in the evaluation of the postoperative shoulder. The purpose of this study was to investigate the diagnostic performance of MR arthrography after rotator cuff repair. Materials and Methods Patients Forty-eight patients (31 males, 17 females; mean age, 50.3 years; age range, years) were included in this retrospective study in a consecutive fashion if the following criteria were met: recurrent symptoms after rotator cuff repair, MR arthrography performed according to our institution s standard protocol no longer than 6 months before revision surgery, and a surgical report including a precise description of rotator cuff morphology. The mean interval between MR arthrography and revision surgery was 53 days (range, days). The initial repair was performed during an open procedure in 40 patients and during arthroscopy in eight patients. Transosseous refixation was performed in 15 patients, a tendon suture was used in three patients, and suture anchors were used in five patients; for 25 patients, no detailed surgical data were available. efore revision surgery the following symptoms were encountered, with more than one symptom possible in any patient: Forty patients had shoulder pain, 14 complained about shoulder weakness, and 14 reported limited range of motion for the shoulder. Revision surgery was performed during an open procedure in 28 patients and during arthroscopy in 20 patients. The following diagnoses were made during revision surgery: Twenty-one supraspinatus tendons had a full-thickness defect, 19 had a partial-thickness defect, and eight were in- JR:186, January

2 tact. Fourteen infraspinatus tendons had a fullthickness defect and three, a partial-thickness defect; 31 were intact. Eleven subscapularis tendons had a full-thickness defect, six had a partial-thickness defect (superior border of the tendon involved), and 31 were intact. In 19 patients, one tendon was involved (supraspinatus tendon, n = 16; subscapularis tendon, n = 3). In 17 patients, two tendons were involved (supraspinatus and infraspinatus tendons, n = 10; supraspinatus and subscapularis tendons, n = 7). In seven patients, all three tendons were involved. The institutional review board responsible for our institution does not require approval for the review of patients records or images for each single study. Patient rights are protected by a law that requires that patients are informed about the possibility of scientific review of their anonymous data and that they have the opportunity to reject such use of their data. Imaging Protocol For MR arthrography, the joint was injected under fluoroscopic guidance. The intraarticular needle position was verified by injecting 1 ml of iopamidol (Iopamiro 200, racco Diagnostics). Subsequently, 10 ml of gadopentetate dimeglumine (2 mmol/l [Magnevist, Schering]) and 1 ml of mepivacaine hydrochloride (Scandicain 2%, strazeneca) were injected. The Swiss drug administration (Swissmedic) has approved the use of gadolinium for intraarticular injection. The MR examination was performed within 15 min or less after injection either on a 1.5-T scanner (Magnetom Symphony, Siemens Medical Solutions) or a 1.0-T scanner (Magnetom Expert, Siemens). dedicated shoulder coil was used. The protocol on the 1.5-T scanner included a coronal oblique proton density weighted fat-saturated turbo spin-echo (SE) sequence (TR/TE, 2,350/15; field of view, mm; matrix, ; section thickness, 4 mm; number of signals averaged, 1; turbo factor, 7), a coronal oblique T2- weighted fat-saturated turbo SE sequence (3,000/91; field of view, mm; matrix, ; section thickness, 4 mm; number of signals averaged, 1; turbo factor, 7), a coronal oblique T1- weighted fat-saturated SE sequence (792/12; field of view, mm; matrix, ; section thickness, 3 mm), a sagittal oblique T1-weighted SE sequence (500/12; field of view, mm; matrix, ; section thickness, 4 mm), and an axial T1-weighted SE sequence (500/12; field of view, mm; matrix, ; section thickness, 3 mm). The imaging protocol on the 1.0-T scanner included a coronal oblique dual-echo turbo SE sequence (TR/TE first echo, second echo, 3,500/15, 105; field of view, 180 mm; matrix, ; section thickness, 4 mm; number of signals averaged, 3; turbo factor, 7), a coronal oblique T1-weighted fatsaturated SE sequence (TR/TE, 800/20; field of view, 160 mm; matrix, ; section thickness, 4 mm), a sagittal oblique T1-weighted turbo SE sequence (700/12; field of view, 160 mm; matrix, ; section thickness, 5 mm; number of signals averaged, 4; turbo factor, 2), and an axial T1- Fig year-old man with full-thickness defect of rotator cuff., Coronal oblique T2-weighted turbo spin-echo (SE) image (TR/TE, 3,500/105) shows supraspinatus tendon defect (arrowheads)., Coronal oblique T1-weighted fat-saturated turbo SE image (800/20) shows contrast material within full-thickness defect (arrows) and within subacromial bursa. Fig year-old woman with partial-thickness defect of rotator cuff., Coronal oblique T2-weighted turbo spin-echo (SE) image (TR/TE, 3,500/105) shows subtle articular-sided partialthickness substance defect of supraspinatus tendon (arrow)., Coronal oblique T1-weighted fat-saturated turbo SE image (800/20) shows contrast material within defect (arrow). Susceptibility artifacts are visible around major tuberosity. 238 JR:186, January 2006

3 MR rthrography fter Rotator Cuff Repair weighted turbo SE sequence (580/20; field of view, 160 mm; matrix, ; section thickness, 4 mm; number of signals averaged, 1; turbo factor, 2). Image nalysis MR examinations were retrospectively analyzed independently by two radiologists. t the time of the study, observer 1 had specialized in musculoskeletal radiology for 10 years and observer 2, a fellowship-trained radiologist, had 2 years experience in musculoskeletal radiology. The observers were blinded with regard to the surgical results. The supraspinatus, infraspinatus, and subscapularis tendons were evaluated separately. full-thickness defect of the supraspinatus or infraspinatus tendon was diagnosed when contrast material was present throughout the tendon substance or when the tendon was not visualized. The presence of contrast material within the subacromial subdeltoid bursa was noted on T1-weighted images. n articular or bursa-sided partial-thickness defect of the supraspinatus or infraspinatus tendons was diagnosed in the presence of contrast material partially entering the articular-sided tendon substance (mainly diagnosed on T1-weighted sequences) and preexisting bursal fluid entering the bursa-sided tendon substance. Subscapularis tendon defects were classified according to a previously published classification [4] in agreement with the criteria used intraoperatively by our orthopedic surgeons. defect involving the cranial third or less of the tendon was described as a partial-thickness defect. Such abnormalities are commonly associated with a lesion of the reflection pulley of the biceps tendon [5]. defect involving more than the cranial third was considered to represent a full-thickness defect. n error analysis was performed after completion of the study by a panel composed of the two original observers, an additional musculoskeletal radiologist with 7 years experience in musculoskeletal MRI, and an orthopedic surgeon specializing in shoulder surgery and experience with MRI of the shoulder. They reviewed the cases that had a discrepancy between MRI and intraoperative findings in the diagnosis of a full-thickness defect. The errors were categorized as follows: difficulty in attributing the lesion to the correct tendon, presence of subacromial contrast material (representing a potential bias toward a full-thickness defect), blooming artifacts, and presence of a severely thinned tendon. Statistics Sensitivity, specificity, diagnostic accuracy, and positive and negative predictive values of MR arthrography were calculated. Interobserver agreement was analyzed with weighted kappa statistics. SPSS software (version 11, Statistical Package for the Social Sciences) was used for statistical analyses. Results For detection of full-thickness defects of the supraspinatus tendon (Fig. 1), the sensitivity was comparable for both observers (observer 1, 19 of 21 defects detected [sensitivity, 90%]; observer 2, 18 of 21 defects detected [sensitivity, 86%]). Specificity was more observer-dependent. detected 24 of 27 tendons without full-thickness defect (specificity, 89%), and observer 2 detected 16 of 27 such tendons (specificity, 59%). ccuracy was 90% (43 of 48 tendons correctly diagnosed) for observer 1 and 71% (34 of 48 tendons correctly diagnosed) for observer 2. For detection of full-thickness infraspinatus defects, sensitivity, specificity, and accuracy for observer 1 were 100% (14 of 14 tendons, 34 of 34 tendons, 48 of 48 tendons), respectively. For observer 2, they were 79%, 94%, and 90% (11 of 14 tendons, 32 of 34 tendons, 43 of 48 tendons), respectively. For detection of full-thickness subscapularis defects, sensitivity, specificity, and accuracy for observer 1 were 82%, 100%, and 96% (nine of 11 tendons, 37 of 37 tendons, 46 of 48 tendons), respectively. For observer 2, they were 91%, 92%, and 92% (10 of 11 tendons, 34 of 37 tendons, 44 of 48 tendons), respectively. Interobserver agreement for the diagnosis of defects of the supraspinatus tendon was moderate (κ = 0.47), good for the infraspinatus tendon (κ = 0.64), and fair for the subscapularis tendon (κ = 0.20). When all three possible diagnoses were taken into consideration (intact tendons, partial-thickness defects, full-thickness defects), observer 1 correctly recognized five of eight intact supraspinatus tendons, 10 of 19 partial-thickness defects (Fig. 2), and 19 of 21 full-thickness defects (Fig. 1), respectively, resulting in an agreement of 71% (34/48). For observer 2, the numbers were three of eight, eight of 19, and 18 of 21 (agreement, 60% [29 of 48 tendons]), respectively. The corresponding numbers (intact tendons, partial-thickness defects, full-thickness defects) for the infraspinatus tendon for observer 1 were 28 of 31, 0 of three, and 14 of 14 tendons (agreement, 88%), respectively. For observer 2, they were 28 of 31, two of three, and 11 of 14 (agreement, 85%). For the subscapularis tendon, observer 1 made the correct diagnosis in 18 of 31, five of six, and nine of 11 tendons (agreement, 67%), respectively. The results for observer 2 were 26 of 31, one of six, and 10 of 11 tendons (agreement, 77%). dditional results are shown in Tables 1 3. Contrast material was found in the subacromial subdeltoid bursa in 24 of the 26 shoulder joints with a full-thickness defect of at least one tendon but also in 13 of 22 joints with intact tendons or with partialthickness defects (Figs. 2 and 3). Correspondingly, contrast material did not leak from the glenohumeral joint space into the subacromial subdeltoid bursa in two of 26 with and in nine of the 22 joints without a full-thickness defect (Fig. 4). The results of the error analysis are summarized in Table 4. More than one error could occur in a specific case. The most common error was incorrect localization of a defect to either the supraspinatus or the infraspinatus tendon on the MR images (five of seven shoulders). Postoperative susceptibility artifacts contributed to the incorrect diagnosis in one of seven cases (Fig. 4). Contrast material leaking into the subacromial bursa may have misled the observers to diagnose a defect at MRI in three of seven cases. In one subscapularis tendon, a false-positive diagnosis of a fullthickness defect was made in the presence of a thin fibrous plate. TLE 1: Supraspinatus Tendon: MR rthrography Versus MR rthrography Finding Intact (n = 8) Defect (n = 19) (n = 21) Intact Partial-thickness defect Full-thickness defect Intact Partial-thickness defect Full-thickness defect JR:186, January

4 TLE 2: Infraspinatus Tendon: MR rthrography Versus MR rthrography Finding Intact (n = 31) Defect (n = 3) (n = 14) Intact Partial-thickness defect Full-thickness defect Intact Partial-thickness defect Full-thickness defect TLE 3: Subscapularis Tendon: MR rthrography Versus MR rthrography Finding Intact (n = 31) Defect (n = 6) (n = 11) Intact Partial-thickness defect Full-thickness defect Intact Partial-thickness defect Full-thickness defect Fig year-old man with intact rotator cuff., Coronal oblique T2-weighted fat-saturated turbo spin-echo (SE) image (TR/TE, 3,000/91) shows intact rotator cuff. Postoperative hyperintensity can be seen within tendon substance (arrow). One observer incorrectly diagnosed case as bursa-sided partial-thickness defect., Coronal oblique T1-weighted fat-saturated turbo SE MR arthrographic image (792/12) shows contrast material within subdeltoid bursa (arrow). Discussion fter surgical repair of the rotator cuff, approximately 25% of patients remain symptomatic [6]. Many may have recurrent or residual rotator cuff defects. The published prevalence of such abnormalities varies between 20% and 47% [7 10]. They are more common in patients with a short interval between the onset of the symptoms and surgery [11]. The prevalence of postoperative defects is higher in symptomatic than in asymptomatic patients (47% vs 21%, respectively) [10]. Symptoms are more common with increasing size of postoperative defects [8, 9, 12]. In our study, MR arthrography showed a diagnostic performance in the diagnosis of fullthickness defects similar to those reported in earlier publications using unenhanced MR examinations [1, 2]. Previously reported sensitivities and specificities of unenhanced MRI vary between % and 25 91%, respectively [1, 2, 13]. For the detection of partial-thickness rotator cuff defects, the reported results are variable. lthough Magee et al. [2] presented a sensitivity and specificity of more than 80%, Owen et al. [1] were unable to distinguish partial rotator cuff defects from distorted but intact tendons. The classification of defects used for the subscapularis tendon differed from the one used for the supra- and infraspinatus tendons because it was based on the craniocaudal extent of the lesion [4]. This classification is the same as the one used by orthopedic surgeons and reflects the typical development of subscapularis defects that is, in a craniocaudal direction. Postoperative distortion and scarring may lead to tendon surface irregularities mimicking partial-thickness defects [10, 14]. In addition, fluid-sensitive sequences may show intratendinous signal abnormalities mimicking a tendon defect. Such abnormalities may persist for a long time postoperatively [10]. Contrast material leaking into the subacromial subdeltoid bursa is known to be of little relevance postoperatively, contrary to the preoperative situation [15, 16]. This has been confirmed by our results. Rather unexpectedly, we found that contrast material does not necessarily leak into the subacromial bursa in the presence of a full-thickness rotator cuff defect. Presumably, such defects are sealed by biomechanically nonfunctional scar tissue. The differentiation of scar tissue from functional but thinned tendon is difficult and can easily lead to diagnostic errors. MR arthrography apparently is not superior to standard MRI in diagnosing partial defects because distortion and signal abnormality of the intact 240 JR:186, January 2006

5 MR rthrography fter Rotator Cuff Repair Fig year-old woman with full-thickness defect not diagnosed on MR arthrography., Coronal oblique T2-weighted turbo spin-echo (SE) image (TR/TE, 3,500/105) with typical postoperative signal irregularity of supraspinatus tendon (arrow). No defect is visible., Coronal oblique T1-weighted fat-saturated turbo SE image (800/20) shows susceptibility artifact (arrows) overlapping supraspinatus tendon. No contrast material is visible within subacromial bursa. TLE 4: Error nalysis of Discrepancies in the Diagnosis of Full-Thickness Defects Discrepancies in the Diagnosis of Full-Thickness Defects Subacromial Contrast Material Severely Thinned Tendon natomic looming Tendon No. of Errors a ttribution rtifact Supraspinatus Infraspinatus Subscapularis 1 1 a More than one source of error per missed diagnosis possible. tendon cause the same problems for both types of examinations. The retrospective design of our study represents an important limitation. The surgical data of the initial operations were commonly incomplete because most of the patients were initially treated outside our institution. Surgical reports for the second operation were incomplete with regard to abnormalities not relating to the rotator cuff. Therefore, potential advantages of MR arthrography in diagnosing abnormalities of articular cartilage and the labrum were not evaluated. In conclusion, postoperative full-thickness defects of the rotator cuff are reliably diagnosed with MR arthrography. The performance of MR arthrography in the diagnosis of partial-thickness defects is only moderate. MR arthrography does not improve the diagnostic performance compared with the results of standard MRI reported in the literature. References 1. Owen RS, Iannotti JP, Kneeland J, Dalinka MK, Deren J, Oleaga L. Shoulder after surgery: MR imaging with surgical validation. Radiology 1993; 186: Magee TH, Gaenslen ES, Seitz R, Hinson G, Wetzel LH. MR imaging of the shoulder after surgery. JR 1997; 168: Hodler J, Kursunoglu-rahme S, Snyder SJ, et al. Rotator cuff disease: assessment with MR arthrography versus standard MR imaging in 36 patients with arthroscopic confirmation. Radiology 1992; 182: Pfirrmann CW, Zanetti M, Weishaupt D, Gerber C, Hodler J. Subscapularis tendon tears: detection and grading at MR arthrography. Radiology 1999; 213: Weishaupt D, Zanetti M, Tanner, Gerber C, Hodler J. Lesions of the reflection pulley of the long biceps tendon: MR arthrographic findings. Invest Radiol 1999; 34: Wolfgang GL. Surgical repair of tears of the rotator cuff of the shoulder: factors influencing the result. J one Joint Surg m 1974; 56: Knudsen H, Gelineck J, Sojbjerg JO, Olsen S, Johannsen HV, Sneppen O. Functional and magnetic resonance imaging evaluation after single-tendon rotator cuff reconstruction. J Shoulder Elbow Surg 1999; 8: Gazielly DF, Gleyze P, Montagnon C. Functional and anatomical results after rotator cuff repair. Clin Orthop Relat Res 1994; 304: Harryman DT 2nd, Mack L, Wang KY, Jackins SE, Richardson ML, Matsen F 3rd. Repairs of the rotator cuff: correlation of functional results with integrity of the cuff. J one Joint Surg m 1991; 73: Zanetti M, Jost, Hodler J, Gerber C. MR imaging after rotator cuff repair: full-thickness defects and bursitis-like subacromial abnormalities in asymptomatic subjects. Skeletal Radiol 2000; 29: Gerber C, Fuchs, Hodler J. The results of repair of massive tears of the rotator cuff. J one Joint Surg m 2000; 82: Galatz LM, all CM, Teefey S, Middleton WD, Yamaguchi K. The outcome and repair integrity of completely arthroscopically repaired large and massive rotator cuff tears. J one Joint Surg m 2004; 86: Motamedi R, Urrea LH, Hancock RE, Hawkins RJ, Ho C. ccuracy of magnetic resonance imaging in determining the presence and size of recurrent rotator cuff tears. J Shoulder Elbow Surg 2002; 11: Spielmann L, Forster, Kokan P, Hawkins RH, Janzen DL. Shoulder after rotator cuff repair: MR imaging findings in asymptomatic individuals initial experience. Radiology 1999; 213: Calvert PT, Packer NP, Stoker DJ, ayley JI, Kessel L. rthrography of the shoulder after operative repair of the torn rotator cuff. J one Joint Surg r 1986; 68: DeOrio JK, Cofield RH. Results of a second attempt at surgical repair of a failed initial rotator-cuff repair. J one Joint Surg m 1984; 66: JR:186, January