Dual-Energy Computed Tomography Arthrography of the Shoulder Joint Using Virtual Monochromatic Spectral Imaging: Optimal Dose of Contrast Agent and Monochromatic Energy Level

OBJECTIVE: To optimize the dose of contrast agent and the level of energy for dual-energy computed tomography (DECT) arthrography of the shoulder joint and to evaluate the benefits of the optimized imaging protocol. MATERIALS AND METHODS: Dual-energy scans with monochromatic spectral imaging mode and conventional single energy scans were performed on a shoulder phantom with 10 concentrations from 0 to 210 mg/mL of iodinated contrast medium at intervals of 15 or 30 mg/mL. Image noise, tissue contrast, and beam hardening artifacts were assessed to determine the optimum dose of contrast agent and the level of monochromatic energy for DECT shoulder arthrography in terms of the lowest image noise and the least beam hardening artifacts while good tissue contrast was maintained. Material decomposition (MD) imaging for bone-iodine differentiation was qualitatively assessed. The optimized protocol was applied and evaluated in 23 patients. RESULTS: The optimal contrast dose and energy level were determined by the phantom study at 60 mg/mL and 72 keV, respectively. This optimized protocol for human study reduced the image noise and the beam-hardening artifacts by 35.9% and 44.5%, respectively. Bone-iodine differentiation by MD imaging was not affected by the iodine concentration or level of energy. CONCLUSION: Dual-energy scan with monochromatic spectral imaging mode results in reduced image noise and beam hardening artifacts.

The Usefulness and Indications of Arthrosonography to Differentiate Full-thickness Tears from Partial-thickness Tears of the Rotator Cuff

OBJECTIVE: To investigate the usefulness and indications of arthrosonography by testing if the new technique could provide additional information on the degrees of rotator cuff tears when compaired to the findings of conventional ultrasonographic examinations. METHOD: Thirty six patients, who were identified to have partial or full-thickness rotator cuff tears by conventional ultrasonography, were included. Intraarticular injection of 15 ml of fluid was performed via posterior approach under ultrasound-guidance, which was followed by arthrosonography. RESULTS: Among 26 patients with partial-thickness tear which was detected by the conventional ultrasonography, eight were identified to have full-thickness tears by the arthrosonography. Although the difference was not significant, the grade 3 partial-thickness tear in the conventional sonography had a higher rate of being identified as full- thickness tear in the arthrosonography than the grade 2 partial-thickness tears. The size of partial-thickness tear was increased after instillation of fluid in the arthrosonography. CONCLUSION: Arthrosonography would be useful in differentiating partial- and full-thickness tears. When a tear of the rotator cuff tendon, especially a grade 3 partial-thickness tear, is detected in the conventional sonographic examination, an obscured full-thickness tear should be suspected and subsequent arthrosonographic procedure could be administered to clarify the extent of the lesion. Moreover, arthrosonography might be helpful in detecting partial-thickness tears by making them appear larger after instillation of fluid.

16-Slice MDCT Arthrography of the Shoulder: Accuracy for Detection of Glenoid Labral and Rotator Cuff Tears

PURPOSE: We wanted to determine the diagnostic accuracy of 16-slice MDCT arthrography (CTA) for glenoid labral and rotator cuff tears of the shoulder. MATERIALS AND METHODS: We enrolled forty-five patients who underwent arthroscopy after CTA for pain or instability of the shoulder joint. The CTA images were analyzed for the existence, sites and types of glenoid labral tears and the presence and severity of rotator cuff tears. We determined the sensitivity, specificity and accuracy of CTA for detecting glenoid labral and rotator cuff tears on the basis of the arthroscopy findings. RESULTS: At arthroscopy, there were 33 SLAP lesions (9 type I, 23 type II and 1 type III), 6 Bankart lesions and 31 rotator cuff lesions (21 supraspinatus, 9 infraspinatus and 1 subscapularis). On CTA, the sensitivity, specificity and accuracy for detecting 24 SLAP lesions, excluding the type I lesions, were 83%, 100% and 91%, the total rotator cuff tears were 90%, 100% and 98%, the full thickness supraspinatus tendon tears were 100%, 94% and 96%, and the partial thickness supraspinatus tendon tears were 29%, 100% and 89%, respectively. CONCLUSION: 16-slice MDCT arthrography has high accuracy for the diagnosis of abnormality of the glenoid labrum or rotator cuff tears and it can be a useful alternative to MRI or US.

Feasibility of Ultrasonography and MR Arthrography during Evaluation of Rotator Cuff Injury

PURPOSE: To evaluate the feasibility of MR arthrography and ultrasonography in evaluating shoulder pain. MATERIALS AND METHODS: The subject group consisted of all patients who visited our institute complaining of shoulder pain or instability from June 2002 to December 2004. There were a total of 92 patients with a mean age of 48. On the basis of arthroscopic results, the sensitivity, specificity, and accuracy of ultrasonography and MR arthrography were evaluated by comparing them with each other. RESULTS: In the diagnosis of supraspinatus tendon tears, ultrasonography had sensitivity and specificity of 100% and 64%, respectively, whereas MR arthrography had sensitivity and specificity of 80% and 94%, respectively. Ultrasonography also had high sensitivity and specificity in the diagnosis of subscapularis tendon tears (100% and 90%). MR arthrography was appropriate for identifying glenoid labral abnormalities (sensitivity, 95% and specificity, 61%). Similar results from ultrasonography and MR arthrography were obtained in the diagnosis of subscapular tendon tears or full-thickness tears of the rotator cuff tendons (kappa value, 0.644 and 0.911). CONCLUSION: While evaluating rotator cuff abnormalities, ultrasonography was appropriate for screening, whereas MR arthrography was useful to confirm the results of the ultrasonography.

Arthrosonography of the Shoulder Joint for Evaluation of the Glenoid Labrum, Glenoid Rim and Humeral Head: Comparison with Conventional Ultrasonography and MR Arthrography

PURPOSE: To compare the diagnostic role of arthrosonography, conventional ultrasonography and MR arthrography in the assessment of glenoid labral tear, glenoid rim fracture and humeral head fracture of the shoulder joint. MATERIALS AND METHODS: The findings of arthrosonography, conventional ultrasonography and MR arthrography were prospectively evaluated in 62 consecutive patients with chronic pain or a history of recurrent dislocation of the shoulder joint. The glenoid labrum was arbitrarily divided into four quadrants: anterosuperior, anteroinferior, posterosuperior, and posteroinferior, and for each, visibility at arthrosonography and conventional ultrasonography was subjectively scored as one of four grades. By means of statistical analysis, the two techniques were then compared. Twenty-six patients subsequently underwent arthroscopy, and the presence or absence of labral tear, glenoid rim fracture and humeral head fracture was determined. The sensitivity and specificity of each modality were separately calculated for each of the three types of shoulder joint injury, and observed differences in these findings were statistically analysed. RESULTS: For all individual quadrants of the labrum, visibility at arthrosonography was higher than at conventional ultrasonography (p.05), though its specificity was significantly higher (p=.003). In this respect, there was no significant difference in sensitivity or specificity between arthrosonography and MR arthrography (p>.05). For the detection of glenoid rim and humeral head fracture, there were no statistical differences in sensitivity and specificity between the three imaging modalities (p> .05). CONCLUSION: Compared with conventional ultrasonography, arthrosonography provides higher visibility of the labrum, thus improving the capacity of ultrasonography to detect labral tear. Arthrosonography could therefore be useful in the diagnosis of labral tear, glenoid rim fracture and humeral head fracture, and may thus partially replace MR arthrography.

Comparison between Conventional MR Arthrograhphy and Abduction and External Rotation MR Arthrography in Revealing Tears of the Antero-Inferior Glenoid Labrum

OBJECTIVE: To compare, in terms of their demonstration of tears of the anterior glenoid labrum, oblique axial MR arthrography obtained with the patient's shoulder in the abduction and external rotation (ABER) position, with conventional axial MR arthrography obtained with the patient's arm in the neutral position. MATERIALS AND METHODS: MR arthrography of the shoulder, including additional oblique axial sequences with the patient in the ABER position, was performed in 30 patients with a clinical history of recurrent anterior shoulder dislocation. The degree of anterior glenoid labral tear or defect was evaluated in both the conventional axial and the ABER position by two radiologists. Decisions were reached by consensus, and a three-point scale was used: grade 1=normal; grade 2=probable tear, diagnosed when subtle increased signal intensity in the labrum was apparent; grade 3=definite tear/defect, when a contrast material-filled gap between the labrum and the glenoid rim or deficient labrum was present. The scores for each imaging sequence were averaged and to compare conventional axial and ABER position scans, Student's t test was performed. RESULTS: In 21 (70%) of 30 patients, the same degree of anterior instability was revealed by both imaging sequences. Eight (27%) had a lower grade in the axial position than in the ABER position, while one (3%) had a higher grade in the axial position. Three whose axial scan was grade 1 showed only equivocal evidence of tearing, but their ABER-position scan, in which a contrast material-filled gap between the labrum and the glenoid rim was present, was grade 3. The average grade was 2.5 (SD=0.73) for axial scans and 2.8 (SD=0.46) for the ABER position. The difference between axial and ABER-position scans was statistically significant (p<0.05). CONCLUSION: MR arthrography with the patient's shoulder in the ABER position is more efficient than conventional axial scanning in revealing the degree of tear or defect of the anterior glenoid labrum. When equivocal features are seen at conventional axial MR arthrography, oblique axial imaging in the ABER position is helpful.

Comparison of Shoulder Positions at MR Arthrography: Change of Labroligamentous Complex Shape and Diagnosis of Labral Tears

PURPOSE: To compare the neutral, internal, and external rotation positions of the glenohumeral joint during magnetic resonance (MR) arthrography performed to assess changes in the shape of the labroligamentous complex (LLC) and in the labral tear. MATERIALS AND METHODS: MR arthrography of the shoulder was retrospectively evaluated in 36 patients aged 14-66 (mean, 40) years. Fourteen cases were confirmed by arthroscopic surgery (7 SLAP lesions, 2 Bankart lesions, 1 both SLAP and Bankart lesions). Axial fat-suppressed T1-weighted spin-echo images were acquired with each shoulder in the neutral position, and with internal and external rotations. In each position, we measured the angle of rotation between the perpendicular line on the glenoid fossa and the long axis of the humeral head, analyzing the relationship between the rotational angle and changes in the shape of the LLC at each internal and external rotation, relative to the neutral position. In addition, labral tears in 14 arthroscopically confirmed joints were evaluated in each position. RESULTS: Mean angles of rotation relative to the neutral position were 44.1 and 45.3 degrees in internal and external rotation, respectively. Changes in the anterior LLC occurred in 25 and 24 cases of internal and external rotation, respectively. There was a significantly meaningful relationship between rotational angle and change in the shape of the anterior LLC during external rotation, and when this change was noticed, the rotational angle was wider (p<0.05). The posterior LLC changed in shape in 13 and 16 cases of internal and external rotation, respectively, but changes according to the angle of rotation were not statistically significant. In arthroscopically confirmed joints, diagnosis of the eight SLAP lesions at external rotation tended to become more accurate, but no statistically significant differences were noted (p=0.07). Two Bankart lesions were interpreted as a tear in all three positions, and one other such lesion was interpreted as a tear in the neutral position and at external rotation, and a possible tear at internal rotation. CONCLUSION: In shoulder MR arthrography, changes in the shape of the anterior LLC were statistically prominent according to the angle of external rotation, and accuracy of diagnosis in SLAP lesions tended to be significantly higher at external rotation. If a SLAP lesion causes clinical concern, additional axial MR arthrography with the shoulder externally rotated is suggested.

Adhesive Capsulitis of the Shoulder: MR Arthrography

PURPOSE: Adhesive capsulitis is a clinical syndrome involving pain and decreased joint motion caused by thickening and contraction of the joint capsule. The purpose of this study is to describe the MR arthrographic findings of this syndrome. MATERIALS AND METHODS: Twenty-nine sets of MR arthrographic images were included in the study. Fourteen patients had adhesive capsulitis diagnosed by physical examination and arthrography, and their MR arthrographic findings were compared with those of 15 subjects in the control group. The images were retrospectively reviewed with specific attention to the thickness of the joint capsule, volume of the axillary pouch (length, width, height(depth)), thickness of the coracohumeral ligament, presence of extra-articular contrast extravasation, and contrast filling of the subcoracoid bursa. RESULTS: Mean capsular thickness measured at the inferior portion of the axillary pouch was 4.1 mm in patients with adhesive capsulitis and 1.5 mm in the control group. The mean width of the axillary pouch was 2.5 mm in patients and 9.5 mm in controls. In patients, the capsule was significantly thicker and the axillary pouch significantly narrower than in controls (p<0.05). Capsule thickness greater than 2.5 mm at the inferior portion of the axillary pouch (sensitivity 93%, specificity 80%) and a pouch narrower than 3.5 mm (sensitivity 93%, specificity 100%) were useful criteria for the diagnosis of adhesive capsulitis. In patients with this condition, extra-articular contrast extravasation was noted in six patients (43%) and contrast filling of the subcoracoid bursa in three (21%). CONCLUSION: The MR arthrographic findings of adhesive capsulitis are capsular thickening, a low-volume axillary pouch, extra-articular contrast extravasation, and contrast filling of the subcoracoid bursa. Capsule thickness greater than 2.5 mm at the inferior portion of the axillary pouch and a pouch width of less than 3.5 mm are useful diagnostic imaging characteristics.