Does Immobilization Post Injection Reduce Contrast Extravasation in MR Arthrography of the Shoulder?

BACKGROUND: Contrast leakage after arthrography is common. We sought to investigate if immobilization could prevent it. PURPOSE: The purpose of this study was to determine the effects on contrast extravasation and image quality produced by strict immobilization of the shoulder between arthrography puncture and subsequent MR imaging. MATERIAL AND METHODS: Fifty patients underwent shoulder MR arthrography using a standard shoulder puncture in the anteroinferior quadrant. Ten milliliters of contrast mixture of saline, iodinated contrast, and gadolinium contrast was injected by a senior musculoskeletal (MSK) radiologist using a 21G needle. Half of the patients were immediately immobilized using a shoulder sling, and the other half were allowed to move their shoulder and arm freely during the time before MR imaging. MR arthrography was performed with a 3 T system using standard T1 and PD weighted sequences. The MR images were reviewed independently by 2 MSK radiologists and graded for extravasation using a five-point scale (1: none, 2: less than 2 cm, 3: 2-5 cm, 4: 5-10 cm, 5: more than 10 cm) and for image quality using a 5 point scale (1: poor, 5: good). The Pearson correlation was calculated to assess the correlation between leakage and image quality. RESULTS: There was no significant difference in amount of leakage between both groups, and global image quality was found equal in both groups. A negative correlation was found between leakage and quality assessment. CONCLUSION: This study shows that it cannot be avoided by strict shoulder immobilization and that it negatively affects image quality and interpretation.

Sonography of a rupture of the tendon of the extensor pollicis longus muscle: initial clinical experience and correlation with findings at cadaveric dissection.

OBJECTIVE: The objectives of our study were to report our initial clinical experience with sonography of the wrist for diagnosing a proximal rupture of the tendon of the extensor pollicis longus (EPL) muscle and to perform sonographic-anatomic correlation of the EPL tendon. MATERIALS AND METHODS: Clinical and imaging files of five patients who underwent sonography and subsequent open wrist surgery were reviewed retrospectively. Imaging was performed by four radiologists experienced in musculoskeletal sonography. Tendon retraction was evaluated on sonography and at surgery. In cadavers, sonography was performed in concert by two musculoskeletal radiologists during progressive stages of dissection of four embalmed specimens. One specimen was sliced in the transverse plane. RESULTS: In cadavers, the EPL tendon was located on or adjacent to Lister's tubercle and extended to the base of the thumb. The EPL tendon crossed over the extensor carpi radialis tendons where it exhibited a flattened aspect. In the five patients in the study, a tubular-shaped hypoechoic area was evident at the position of the ruptured EPL tendon on sonograms. At surgery, this area corresponded to fluid, hemorrhage, and scar tissue in the EPL tendon sheath. The assessment of tendon retraction on sonography correlated with findings at surgery. CONCLUSION: Sonography may aid in diagnosing a rupture of the EPL tendon and in the preoperative assessment of gap size and position of the retracted tendon ends. A characteristic tubular hypoechoic area may be seen crossing over the extensor carpi radialis tendons.

Meniscal tears: comparison of half-Fourier technique and conventional MR imaging.

PURPOSE: To determine whether half-Fourier MR image acquisition technique can provide similar information to that of conventional MR acquisition technique for evaluation of meniscal tears. MATERIALS AND METHODS: We studied 101 menisci in 52 patients who were referred for evaluation of meniscal tears. Sagittal MR images of the knee were obtained for all patients by using proton density and T2-weighted SE sequences on a 1-T clinical system. The half-Fourier technique and conventional technique were used for all patients. All other imaging parameters were identical for both sequences (TR/TE=2400/20,70; 3 mm slice thickness; 200 x 256 matrix; field of view, 200; one signal acquired). Both sets of images were filmed with standard window and level settings. Images were randomised and interpreted independently by two radiologists for the presence of meniscal tears. Images were also subjectively assessed for image quality using a five-point grading scale. RESULTS: On half-Fourier images, Reader 1 interpreted 23 menisci as torn, compared to 28 for Reader 2. On conventional images, Reader 1 interpreted 24 menisci as torn, compared to 26 for Reader 2. Agreement between interpretation of the conventional and that of the half-Fourier images was 99% for Reader 1, and 98% for Reader 2. Agreement between readers for the half-Fourier images was 95%, and for the conventional images 96%. No statistically significant difference was found in the subjective evaluation of image quality between the conventional and half-Fourier images. CONCLUSION: The half-Fourier acquisition technique compares favourably with the conventional technique for the evaluation of meniscal tears.