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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.

The purpose of this study was to optimize CT arthrography technique and determine if dual energy CT (DECT) can provide any benefit over single energy CT (SECT). Iodinated contrast attenuation at different concentrations was measured using DECT and SECT at different beam energies (140, 120, and 80 kVp). Dose and noise were measured on phantoms at different tube currents. Three bovine femoral condyles with artificially created cartilage defects were scanned with dose-equivalent protocols. Contrast-to-noise ratio (CNR) between cartilage and iodine was measured, and the appearance of cartilage defects was graded by two readers. DECT scans were post-processed for iodine quantification. The beam energy 80 kVp had the highest iodine signal, 50% greater than DECT, 75% greater than 120 kVp, and 100% greater than 140 kVp. Noise was nearly identical for all techniques when dose was matched. The 80 kVp level had the highest CNR, 25% higher than 120 kVp and DECT, and 33% greater than 140 kVp. The 80 kVp technique was also preferred by both readers. DECT iodine quantification was significantly limited by the post-processing application, noise, and beam hardening. In this in-vitro study, the SECT 80 kVp CT arthrography technique was superior to currently performed 120 and 140 kVP SECT techniques and DECT.

Imaging has become an important clinical tool in the evaluation of articular cartilage, both in the clinical and research setting. This article reviews the mechanisms of articular cartilage injury in the lower extremities and their implications. Specific examples of acute and chronic repetitive injuries in the hip, knee, and ankle are used to demonstrate the characteristics of articular cartilage lesions on magnetic resonance imaging and multidetector computed tomographic arthrography. Loss of meniscal function in the knee and femoroacetabular impingement in the hip represent sources of repetitive cartilage injury that predispose the joint to osteoarthritis. Acute cartilage injury is exemplified by osteochondral lesions of the talus, which may result in post-traumatic osteoarthritis. Recognition of early cartilage damage and associated lesions may help determine the proper treatment for the patient to delay or prevent progression to osteoarthritis.

Objective: To determine the diagnostic yield, accuracy, and safety of computed tomography (CT) fluoroscopy guidance for musculoskeletal biopsies., Materials and Methods: A retrospective analysis of musculoskeletal biopsies performed with CT fluoroscopy guidance over a 2-year period was made. Data collected were biopsy sites, CT fluoroscopic times, and biopsy results. Results were categorized as the following: positive, negative (but diagnostic), or nondiagnostic. Reference standard consisted of 5 years of follow-up to verify results., Results: Ninety-five CT fluoroscopy-guided musculoskeletal biopsies were performed. Bone biopsies comprised 83% (79/95), and soft tissue biopsies comprised 17% (16/95). The mean age was 54 years (range, 16-90 years); 40.0% (38/95) were male subjects, and 60.0% (57/95) were female subjects. For all subjects, CT fluoroscopic times ranged from 2 to 310 seconds, with a mean time of 63 seconds and a median time of 34 seconds. The diagnostic yield was 96% (91/95), with a nondiagnostic result in 4% (4/95) of subjects. Diagnostic biopsy specimens showed a positive result in 63% (60/95) of subjects and a negative but diagnostic result in 33% (31/95) of subjects. There were no major complications., Conclusions: Computed tomography fluoroscopic-guided musculoskeletal biopsies show a high diagnostic yield and are accurate and safe. The biopsy results are similar or superior to other published reports using conventional CT guidance with only a small overall fraction being nondiagnostic. The benefits of real-time imaging are at the cost of operator exposure to ionizing radiation and the risk of potentially high exposures to both patient and operator. The impact on indications for which lesions are most amenable to percutaneous biopsy using CT fluoroscopy and procedure time has yet to be determined.

Objective: To preliminarily evaluate a new CT-biopsy guidance device, the SeeStar (Radi, Uppsala, Sweden), for use in musculoskeletal applications., Design: The device was evaluated using an imaging phantom and in various simulated clinical biopsy situations. The phantom study was undertaken to optimize the linear metallic artifacts produced by the guidance device. The phantom and guidance device were imaged with CT after altering different imaging parameters, including field of view, filter, focal spot size, kV, mAs, slice thickness and pitch. Clinical biopsy situations were simulated for a superficial biopsy, a deep biopsy and a horizontal biopsy approach., Results: Altering CT parameters had little effect on the subjective appearance of the linear metal artifact, which is used to plan the biopsy approach. Placement of an 18-G needle inside of the biopsy device was subjectively helpful in exaggerating the artifact. Use of this artifact could be helpful in planning biopsy approach for deep lesions or lesions near critical structures. The metal guide on the device adequately supports a standard biopsy needle, making it potentially advantageous for biopsy of superficial lesions and lesions approached from a horizontal orientation., Conclusion: Use of this CT-biopsy guidance device is potentially useful for musculoskeletal applications. The linear metal artifact produced by the device can help plan the biopsy approach. The device can also be useful in biopsy situations where the biopsy needle requires external support during imaging.

The role of computed tomography in rheumatologic imaging is limited primarily to joints that have complex anatomy and those obscured by overlying structures. Computed tomography is useful in the evaluation of sacroiliitis, arthritis of the subtalar joints, talocalcaneal coalition, preoperative assessment of the hip and shoulder, abnormalities of the sternoclavicular joint, chondromalacia patellae, and patellofemoral joint subluxation. Although CT is useful in examining ankle tendons, magnetic resonance imaging is preferred.