Advanced arthrography of the shoulder with CT and MR imaging

Anterior Shoulder Instability

The anatomy of the glenohumeral joint prioritizes mobility at the expense of stability and thus predisposes it to injury through dislocation. This article discusses the anatomical basis for instability and how it translates into patterns of injury, focusing on anterior instability. We suggest an approach to imaging the unstable shoulder and examine the imaging features seen in the context of anterior instability, along with consideration of postoperative appearances.

Anterior Glenohumeral Instability: Classification of Pathologies of Anteroinferior Labroligamentous Structures Using MR Arthrography

We examined labroligamentous structures in unstable anteroinferior glenohumeral joints using MR arthrography (MRA) to demonstrate that not all instabilities are Bankart lesions. We aimed to show that other surgical protocols besides classic Bankart repair are appropriate for labroligamentous lesions. The study included 35 patients (33 males and 2 females; mean age: 30.2; range: 18 to 57 years). MRA was performed in all patients. The lesions underlying patients' instability such as Bankart, anterior labral periosteal sleeve avulsion (ALPSA), and Perthes lesions were diagnosed by two radiologists. MRA yielded 16 diagnoses of Bankart lesions, 5 of ALPSA lesions, and 14 of Perthes lesions. Albeit invasive, MRA seems to be a more reliable and accurate diagnostic imaging modality for the classification and treatment of instabilities compared to standard MRI.

MDCT arthrography of the shoulder with datasets of isotropic resolution: indications, technique, and applications

OBJECTIVE

The purposes of this review are to summarize the indications for MDCT arthrography of the shoulder, highlight the features of MDCT acquisition, and describe the normal and abnormal MDCT arthrographic appearances of the shoulder.

CONCLUSION

MDCT arthrography is a valid alternative for shoulder imaging of patients with contraindications to MRI or after failed MRI. MDCT arthrography is accurate for assessment of a variety of shoulder abnormalities and, with further validation, may become the imaging test of choice for evaluation of the postoperative shoulder.

Effect of SonoVue on the synovial membrane in rabbit knees

OBJECTIVES

The purpose of this study was to evaluate the effect of intra-articular injection of SonoVue (sulfur hexafluoride with a phospholipid shell; Bracco SpA, Milan, Italy) on the synovial membrane in an animal model.

METHODS

Twenty-one New Zealand White rabbits (42 knees) were used in this study. We injected the knees with normal saline (saline group; n = 21) and SonoVue (SonoVue group; n = 21). A histologic examination of the knees was performed out at 3 and 12 hours and 3, 7, 15, 30, and 45 days after injection. Four histologic parameters (synovial hyperplasia, synovial stroma, vascular dilatation, and inflammatory infiltrates) were graded separately.

RESULTS

We found no significant differences in this study for synovial hyperplasia, vascular dilatation, or inflammatory infiltrates between the saline and SonoVue groups. A significant difference was only observed for synovial stroma (P < .05), and most of the histologic changes were mild in the saline group and moderate in the SonoVue group. The histologic changes observed in this study are considered transitory and reversible.

CONCLUSIONS

The results suggest that intra-articular injection of SonoVue is a safe procedure.

Direct MR arthrography at 1.5 and 3.0 T: signal dependence on gadolinium and iodine concentrations--phantom study

PURPOSE

To prospectively quantify in vitro the influence of gadopentetate dimeglumine and ioversol on the magnetic resonance (MR) imaging signal observed with a variety of musculoskeletal pulse sequences to predict optimum gadolinium concentrations for direct MR arthrography at 1.5 and 3.0 T.

MATERIALS AND METHODS

In an in vitro study, T1 and T2 relaxation times of three dilution series of gadopentetate dimeglumine (concentration, 0-20.0 mmol gadolinium per liter) at ioversol concentrations with iodine concentration of 0, 236.4, and 1182 mmol iodine per liter (corresponding to 0, 30, and 150 mg of iodine per milliliter) were measured at 1.5 and 3.0 T. The relaxation rate dependence on concentrations of gadolinium and iodine was analytically modeled, and continuous profiles of signal versus gadolinium concentration were calculated for 10 pulse sequences used in current musculoskeletal imaging. After fitting to experimental discrete profiles, maximum signal-to-noise ratio (SNR), gadolinium concentration with maximum SNR, and range of gadolinium concentration with 90% of maximum SNR were derived. The overall influence of field strength and iodine concentration on these parameters was assessed by using t tests. The deviation of simulated from experimental signal-response profiles was assessed with the autocorrelation of the residuals.

RESULTS

The model reproduced relaxation rates of 0.37-38.24 sec(-1), with a mean error of 4.5%. Calculated SNR profiles matched the discrete experimental profiles, with autocorrelation of the residuals divided by the mean of less than 5.0. Admixture of ioversol consistently reduced T1 and T2, narrowed optimum gadolinium concentration ranges (P = .004-.006), and reduced maximum SNR (P < .001 to not significant). Optimum gadolinium concentration was 0.7-3.4 mmol/L at both field strengths. At 3.0 T, maximum SNR was up to 75% higher than at 1.5 T.

CONCLUSION

Admixture of ioversol to gadopentetate dimeglumine solutions results in a consistent additional relaxation enhancement, which can be analytically modeled to allow a near-quantitative a priori optimized match of contrast media concentrations and imaging protocol for a broad variety of pulse sequences.

MR arthrography of the shoulder, hip, and wrist: evaluation of contrast dynamics and image quality with increasing injection-to-imaging time

OBJECTIVE

The purpose of our study was to investigate the contrast dynamics and the relationship between visualization of intraarticular structures and time elapsed between intraarticular injection of contrast agent and MRI in symptomatic patients referred for MR arthrography of the shoulder, hip, and wrist.

SUBJECTS AND METHODS

Our local ethics committees and the national drug administration approved this multicentric study. We prospectively studied 11 shoulders, 11 hips, and 10 wrists. After the intraarticular gadolinium injection, patients underwent a baseline MR arthrography protocol (time point [TP] 1) and subsequent MRI at another four time points (TP 2-TP 5) up to 240 minutes. The course of contrast-to-noise ratio (CNR) over time was calculated. Three observers assessed the degree of visualization of different intraarticular structures and the overall image quality at each time point using a 3-point scale and a 5-point scale, respectively.

RESULTS

For all joints, CNR measurements showed peak CNR at TP 1 (21 minutes) and TP 2 (45 minutes) with a subsequent, near-logarithmic decline of CNR values over time. Visualization of different anatomic structures decreased over time. Overall image quality was insufficient for diagnostic purposes at TP 3 (96 minutes) in three (27%) of 11 shoulders and in three (27%) of 11 hips. In two (20%) of 10 wrists, image quality was insufficient at TP 2 (45 minutes).

CONCLUSION

For MR arthrography, the degree of visualization of intraarticular structures depends on the time elapsed between contrast injection and MRI. MR arthrography of the shoulder and hip should be performed within 90 minutes, and MR arthrography of the wrist should be performed within 45 minutes, after intraarticular injection.

Quantitative evaluation of the relaxivity effects of iodine on GD-DTPA enhanced MR arthrography

PURPOSE

To quantify the effect of iodine on the gadolinium (Gd) contrast-enhanced signal in MR arthrography.

MATERIALS AND METHODS

Saline solutions of Gd contrast agent (0-1 mmol/liter) were mixed with iodinated contrast agent (0-185 mmol/liter). The T1 and T2 relaxation constants of these solutions were measured at 1.5T. Different types of commonly used iodinated contrast agents as well as sodium iodide (NaI) solutions were also analyzed.

RESULTS

Iodine caused significant T2 shortening and some T1 shortening in Gd contrast solutions. Both contrast agents independently obeyed the standard relaxation relation, and their mixture obeyed a modified version of this relation. The side chains in various iodine molecules and their viscosities affected the relaxation properties differently. For various spin-echo (SE) sequences, the signal from synovial fluid containing different concentrations of the two contrast agents was calculated. The T2-weighted signal appeared to be most affected by the increase in iodine concentrations. In the absence of Gd contrast, all SE sequences showed an initial increase in signal from iodine contrast.

CONCLUSION

A generalized relation for the relaxivities of Gd contrast in the presence of iodine was established. The side chains of iodine contrast were found to alter the relaxivities of Gd contrast. Imaging with proton density (PD)-weighted SE with only iodine contrast agent was found to be feasible.

Optimization of gadodiamide concentration for MR arthrography at 3 T

OBJECTIVE

The purpose of our study was to determine the optimal concentration of a gadolinium-based contrast agent (gadodiamide) for direct MR arthrography at 3 T compared with 1.5 T in an in vitro study.

CONCLUSION

Optimized concentrations of gadolinium-based contrast agents for MR arthrography are similar at 3 and 1.5 T, although a slightly greater dilution may be useful at 3 T. Signal-to-noise ratio peak levels are significantly reduced by adding an iodinated contrast agent, relatively significantly more at 3 T than at 1.5 T.

MR Arthrography of the Knee: How, Why, When

MR arthrography combines the techniques of arthrography with MR imaging to benefit from the added imaging information afforded by intra-articular distention. This article reviews technical considerations for MR arthrography, potential complications, indications, pitfalls in imaging diagnosis, and commonly encountered pathology. It is an elegant study that can offer precise diagnostic information in the appropriate clinical setting.

MR imaging of shoulder instability injuries in the athlete

Lesions leading to glenohumeral instability may result from acute trauma, atraumatic laxity, or repetitive microtrauma. Athletic activities, especially overhead throwing, may lead to a series of lesions involving the stabilizing structures of the shoulder. The resultant injuries and pathomechanics leading to shoulder symptoms can be classified as primary disease, primary instability, acute traumatic instability, and posterosuperior impingment syndrome. MR imaging with or without intrarticular or intravenous injection of contrast material, along with clinical examination and stress testing, provides valuable preoperative assessment.

Effects of iodinated contrast and field strength on gadolinium enhancement: implications for direct MR arthrography

PURPOSE

To optimize direct magnetic resonance (MR) arthrography by determining the effect of dilution of gadolinium in iodinated contrast, saline, or albumin on T1-weighted, T2-weighted, and gradient-recalled echo (GRE) images, and the effect of scanner field strength.

MATERIALS AND METHODS

Gadopentetate dimeglumine was diluted into normal saline, albumin, or iodinated contrast (0.625 mmol/liter to 40 mmol/liter). Samples were scanned at 1.5T and 0.2T. Signal intensity was measured using T1-weighted spin-echo (SE), T2-weighted SE, and two- and three-dimensional GRE (20 degrees-75 degrees flip angle) sequences. Graphical analysis of signal intensity vs. gadolinium concentration was performed.

RESULTS

Albumin had no effect on gadolinium contrast. Dilution of gadolinium in iodinated contrast decreased signal intensity on all sequences compared to samples of identical concentration diluted in saline at both 1.5T and 0.2T: with a 2 mmol/liter gadolinium solution at 1.5T, signal was decreased by 26.1% on T1-weighted images, 31.7% on GRE20 images, and 28.9% on GRE45 images, and the T2 value decreased by 71.1%; at 0.2T, signal was decreased by 23.5% on T1-weighted images. On all sequences, the peak signal shifted to the left (lower gadolinium concentration) when diluted in iodinated contrast. Peak signal was also seen at different gadolinium concentrations on different sequences and field strength: at 1.5T, peak in saline/iodine was 2.5/0.625 mmol/liter on T1-weighted images, and 2.5/1.25 mmol/liter on GRE20 and GRE45 sequences. At 0.2T, peak in saline/iodine was 0.625-2.5/1.25 mmol/liter on T1-weighted images, 0.625-2.5/1.25 on GRE45 images, 2.5-10.0/1.25-5.0 mmol/liter on GRE65 images, and 1.25-5.0/0.625-1.25 mmol/liter on GRE75 images.

CONCLUSION

Dilution of gadolinium in iodinated contrast results in decreased signal on T1-weighted, T2-weighted, and GRE images compared to dilution in saline or albuminfor both 1.5-T and 0.2-T scanners; if gadolinium is diluted in iodinated contrast for MR arthrography, a lower concentration should be used because the peak is shifted to the left. The use of iodinated contrast should be minimized, as it may diminish enhancement and lower the sensitivity and specificity of MR arthrography. Optimal gadolinium concentration for MR arthrography is dependent on scanner field strength and a broader range of gadolinium concentration can be used to provide maximal signal at low field strength.

Temporal behavior of intraarticular gadolinium

PURPOSE

As imaging delays during MR arthrography can result in suboptimal studies and potential pitfalls in diagnosis, we sought to evaluate the temporal behavior of intraarticular Gd-DTPA.

METHOD

We prospectively studied four shoulders, four knees, and four hips. Two of each group received either an intraarticular injection of 3 mmol/L Gd-DTPA and iodinated contrast medium or 2 mmol/L Gd-DTPA and 0.9% saline. We measured contrast-to-noise ratio (CNR) and joint distention on serial T1-weighted sequences. Retrospectively, we measured CNR and imaging delays in 31 MR arthrography patients (20 shoulders, 7 knees, and 4 hips).

RESULTS

In the shoulder, maximal CNR and joint distention occurred at 15 min. CNR decreased 53% by 1 h. In the knee, maximal distention occurred at 1 h, whereas CNR peaked at 2.75 h and then declined 20 and 86% by 3.5 and 6.25 h, respectively. In the hip, peak CNR and distention occurred at 0.5 h. CNR declined 53% by 2 h. Both contrast mixtures yielded similar results.

CONCLUSION

MR arthrography may tolerate imaging delays of 1 h for the shoulder, 2 h for the hip, and 3.5 h for the knee.

Rotator cuff disease

The important role played by the rotator cuff in the stability and movement of the glenohumeral joint make it susceptible to damage and injury in patients of all age groups. A number of extrinsic and intrinsic mechanisms have been described for the development of rotator cuff disease, although it is more likely that the actual etiology in any one individual is multifactorial. The key to successful management in a particular patient is an accurate diagnosis of the underlying cause by thorough clinical examination and the use of appropriate investigations. The mainstay of treatment of patients with rotator cuff disease is nonoperative. Surgical intervention is usually considered only after failure of at least 6 months of conservative therapy. However, there are a few situations where early surgical intervention is indicated.

Direct MR arthrography of the shoulder: is exercise prior to imaging beneficial or detrimental?

PURPOSE

To define the beneficial and detrimental effects of adding exercise to direct magnetic resonance (MR) shoulder arthrography.

MATERIALS AND METHODS

Direct, intraarticular, gadolinium arthrography of the shoulder was performed in 41 patients, who underwent 1.5-T MR imaging before and after 1 minute of arm swinging. Fourteen milliliters of dilute gadolinium solution was injected. Two readers blinded to exercise independently graded the randomly distributed images with a five-point scale for capsular contrast material resorption; extraarticular contrast material leakage; rotator cuff, glenoid labrum, and anterior capsule conspicuity; and partial-thickness or full-thickness rotator cuff tear and labral tear detectability. The sign test was performed to evaluate the significance of differences between preexercise and postexercise grading for each reader. A second review was performed, with direct side-by-side comparison of preexercise and postexercise images.

RESULTS

There was evidence of increased capsular resorption after exercise but no alteration in the depiction of the rotator cuff tendons or glenoid labrum. There was no significant extraarticular contrast material leakage after exercise and no alteration in depiction of the anterior capsule. There was no difference in the detectability of rotator cuff or labral tears.

CONCLUSION

Exercise with direct shoulder MR arthrography has no beneficial or detrimental effect on image quality or on the depiction of rotator cuff or labral tears.