Reproducibility of T1ρ and T2 quantification in a multi-vendor multi-site study.

OBJECTIVE: To evaluate the multi-vendor multi-site reproducibility of two-dimensional (2D) multi-echo spin-echo (MESE) T2 mapping (product sequences); and to evaluate the longitudinal reproducibility of three-dimensional (3D) magnetization-prepared angle-modulated partitioned k-space spoiled gradient echo snapshots (MAPSS) T1ρ and T2 mapping (research sequences), and 2D MESE T2 mapping, separated by 6 months, in a multi-vendor multi-site setting. METHODS: Phantoms and volunteers (n = 5 from each site, n = 20 in total) were scanned on four 3 T magnetic resonance (MR) systems from four sites and three vendors (Siemens, General Electric, and Phillips). Two traveling volunteers (3 knees) scanned at all 4 sites at baseline and 6-month follow-up. Data was transferred to one site for centralized processing. Coefficients of variation (CVs) were calculated to evaluate reproducibility. RESULTS: For baseline 2D MESE T2 measures, average CV were 0.37-2.45% (intra-site) and 5.96% (inter-site) for phantoms, and 3.15-8.49% (intra-site) and 14.16% (inter-site) for volunteers. For longitudinal phantom data, intra-site CVs were 1.42-3.48% for 3D MAPSS T1ρ, 1.77-3.56% for 3D MAPSS T2, and 1.02-2.54% for 2D MESE T2. For the longitudinal volunteer data, the intra-site CVs were 2.60-4.86% for 3D MAPSS T1ρ, 3.33-7.25% for 3D MAPSS T2, and 3.11-8.77% for 2D MESE T2. CONCLUSION: This study demonstrated excellent intra-site reproducibility of 2D MESE T2 imaging, while its inter-site variation was slightly higher than 3D MAPSS T2 imaging (10.06% as previously reported). This study also showed excellent reproducibility of longitudinal T1ρ and T2 cartilage quantification, in a multi-vendor multi-site setting for both product 2D MESE T2 and 3D MAPSS T1p/T2 research sequences.

Multi-vendor multi-site quantitative MRI analysis of cartilage degeneration 10 Years after anterior cruciate ligament reconstruction: MOON-MRI protocol and preliminary results.

OBJECTIVE: To describe the protocol of a multi-vendor, multi-site quantitative MRI study for knee post-traumatic osteoarthritis (PTOA), and to present preliminary results of cartilage degeneration using MR T1ρ and T2 imaging 10 years after anterior cruciate ligament reconstruction (ACLR). DESIGN: This study involves three sites and two MR platforms. The patients are from a nested cohort (termed as Onsite cohort) within the Multicenter Orthopaedic Outcomes Network (MOON) cohort 10 years after ACLR. Phantoms and controls were scanned for evaluating reproducibility. Cartilage was automatically segmented, and T1ρ and T2 were compared between operated, contralateral, and control knees. RESULTS: Sixty-eight ACL-reconstructed patients and 20 healthy controls were included. In phantoms, the intra-site coefficients of variation (CVs) of repeated scans ranged 1.8-2.1% for T1ρ and 1.3-1.7% for T2. The inter-site CVs ranged 1.6-2.1% for T1ρ and 1.1-1.4% for T2. In human subjects, the intra-site scan/rescan CVs ranged 2.2-3.5% for T1ρ and 2.6-4.9% for T2 for the six major compartments. In patients, operated knees showed significantly higher T1ρ and T2 values mainly in medial femoral condyle, medial tibia and trochlear cartilage compared with contralateral knees, and showed significantly higer T1ρ and T2 values in all six compartments compared to healthy control knees. The patient contralateral knees showed higher T1ρ and T2 values mainly in the lateral femoral condyle, lateral tibia, trochlear, and patellar cartilage compared to healthy control knees. CONCLUSION: A platform and workflow with rigorous quality control has been established for a multi-vendor multi-site quantitative MRI study in evaluating PTOA 10 years after ACLR. Our preliminary report suggests significant cartilage matrix changes in both operated and contralateral knees compared with healthy control knees.

Multi-vendor multi-site T1ρ and T2 quantification of knee cartilage.

OBJECTIVE: To develop 3D T1ρ and T2 imaging based on the same sequence structure on MR systems from multiple vendors, and to evaluate intra-site repeatability and inter-site inter-vendor reproducibility of T1ρ and T2 measurements of knee cartilage. METHODS: 3D magnetization-prepared angle-modulated partitioned k-space spoiled gradient echo snapshots (3D MAPSS) were implemented on MR systems from Siemens, GE and Philips. Phantom and human subject data were collected at four sites using 3T MR systems from the three vendors with harmonized protocols. Phantom data were collected by means of different positioning of the coil. Volunteers were scanned and rescanned after repositioning. Two traveling volunteers were scanned at all sites. Data were transferred to one site for centralized processing. RESULTS: Intra-site average coefficient of variations (CVs) ranged from 1.09% to 3.05% for T1ρ and 1.78-3.30% for T2 in phantoms, and 1.60-3.93% for T1ρ and 1.44-4.08% for T2 in volunteers. Inter-site average CVs were 5.23% and 6.45% for MAPSS T1ρ and T2, respectively in phantoms, and 8.14% and 10.06% for MAPSS T1ρ and T2, respectively, In volunteers. CONCLUSION: This study showed promising results of multi-site, multi-vendor reproducibility of T1ρ and T2 values in knee cartilage. These quantitative measures may be applied in large-scale multi-site, multi-vendor trials with controlled sequence structure and scan parameters and centralized data processing.

Meniscus treatment and age associated with narrower radiographic joint space width 2-3 years after ACL reconstruction: data from the MOON onsite cohort.

OBJECTIVE: To identify risk factors for radiographic signs of post-traumatic osteoarthritis (OA) 2-3 years after anterior cruciate ligament (ACL) reconstruction through multivariable analysis of minimum joint space width (mJSW) differences in a specially designed nested cohort. METHODS: A nested cohort within the Multicenter Orthopaedic Outcomes Network (MOON) cohort included 262 patients (148 females, average age 20) injured in sport who underwent ACL reconstruction in a previously uninjured knee, were 35 or younger, and did not have ACL revision or contralateral knee surgery. mJSW on semi-flexed radiographs was measured in the medial compartment using a validated computerized method. A multivariable generalized linear model was constructed to assess mJSW difference between the ACL reconstructed and contralateral control knees while adjusting for potential confounding factors. RESULTS: Unexpectedly, we found the mean mJSW was 0.35 mm wider in ACL reconstructed than in control knees (5.06 mm (95% CI 4.96-5.15 mm) vs 4.71 mm (95% CI 4.62-4.80 mm), P < 0.001). However, ACL reconstructed knees with meniscectomy had narrower mJSW compared to contralateral normal knees by 0.64 mm (95% C.I. 0.38-0.90 mm) (P < 0.001). Age (P < 0.001) and meniscus repair (P = 0.001) were also significantly associated with mJSW difference. CONCLUSION: Semi-flexed radiographs can detect differences in mJSW between ACL reconstructed and contralateral normal knees 2-3 years following ACL reconstruction, and the unexpected wider mJSW in ACL reconstructed knees may represent the earliest manifestation of post-traumatic osteoarthritis and warrants further study.

In vitro toxicity in long-term cell culture of MR contrast agents targeted to cartilage evaluation.

OBJECTIVE: Contrast-enhanced magnetic resonance (MR) imaging methods have been proposed for non-invasive evaluation of osteoarthritis (OA). We measured cell toxicities of cartilage-targeted low-generation dendrimer-linked nitroxide MR contrast agents and gadopentetate dimeglumine (Gd-DTPA) on cultured chondrocytes. DESIGN: A long-term Swarm rat chondrosarcoma chondrocyte-like cell line was exposed for 48-h to different salts (citrate, maleate, tartrate) and concentrations of generation one or two diaminobutyl-linked nitroxides (DAB4-DLN or DAB8-DLN), Gd-DTPA, or staurosporine (positive control). Impact on microscopic cell appearance, MTT spectrophotometric assays of metabolic activity, and quantitative PicoGreen assays of DNA content (cell proliferation) were measured and compared to untreated cultures. RESULTS: Chondrocyte cultures treated with up to 7.5 mM Gd-DTPA for 48-h had no statistical differences in DNA content or MTT reaction compared to untreated cultures. At all doses, DAB4-DLN citrate treated cultures had results similar to untreated and Gd-DTPA-treated cultures. At doses >1 mM, DAB4-DLN citrate treated cultures showed statistically greater DNA and MTT reaction than maleate and tartrate DAB4-DLN salts. Cultures exposed to 5 mM or 7.5 mM DAB8-DLN citrate exhibited rounded cells, poor cell proliferation, and barely detectable MTT reaction. Treatment with 0.1 µM staurosporine caused chondrocyte death. CONCLUSION: Long-term exposure, greater than clinically expected, to either DAB4-DLN citrate or Gd-DTPA had no detectable toxicity with results equivalent to untreated cultures. DAB4-DLN citrate was more biocompatible than either the maleate or tartrate salts. Cells exposed for 48-h to 5 mM or 7.5 mM DAB8-DLN salts demonstrated significant cell toxicity. Further evaluation of DAB8-DLN with clinically appropriate exposure times is required to determine the maximum useful concentration.

Posterior horn medial meniscal root tear: the prequel.

OBJECTIVE: To determine whether subarticular marrow changes deep to the posterior horn medial meniscal root anchor might predict subsequent medial meniscal root tear. MATERIALS AND METHODS: Fifteen patients with MR-diagnosed posterior horn medial meniscal root (PHMMR) tear and a knee MRI antecedent to the tear were identified at three imaging centers over a 7-year period. The pre- and post-tear MR images were evaluated for marrow signal changes deep to the root anchor, meniscal root signal intensity, medial compartment articular cartilage thinning, and meniscal body extrusion. Images of 29 age- and gender-matched individuals with two MRIs of the same knee were reviewed as a control group. RESULTS: MRI in 11 of 15 (73%) cases with subsequent PHMMR tear demonstrated linear subcortical marrow edema deep to the meniscal root anchor on the antecedent MRI compared to only 1 of 29 (3%) non-tear controls (p < 0.0001). The abnormal signal resolved on post-tear MRI in all but two patients. Cyst-like changes deep to the PHMMR were present on initial MRI in three of 15 (23%) cases and three of 29 (10%) controls, persisting in all but one case on follow-up imaging. The PHMMR was gray on the initial MRI in seven of 15 (47%) of cases that developed tears compared to four of 29 (14%) controls (p < 0.0001). There was medial meniscal extrusion (MME) prior to tear in two of 15 (13%) patients and in ten of 15 (67%) patients after PHMMR failure. In the control group, MME was present in one (3%) and three (10%) of 29 subjects on the initial and follow-up MRIs, respectively. Articular cartilage loss was noted in two of 15 (15%) cases before tear and nine of 15 (69%) on follow-up imaging, as compared to one (3%) and four (14%) of 29 subjects in the control group. CONCLUSIONS: Subcortical marrow edema deep to the PHMMR may result from abnormal stresses and thus be a harbinger of meniscal root failure. This hypothesis is supported by resolution of these marrow signal changes after root tear. Following tear, extrusion of the meniscal body results in increased stress on the medial weight-bearing surfaces often leading to articular cartilage loss; we observed this sequence in six of our 15 patients with PHMMR tears.

Radiographic joint space width is correlated with 4-year clinical outcomes in patients with knee osteoarthritis: data from the osteoarthritis initiative.

OBJECTIVE: To evaluate if quantitative joint space width (JSW) measurements from radiographs correlate with 4-year Knee injury and Osteoarthritis Outcome Scores (KOOS) and clinical performance measures. METHOD: The study group consisted of 942 patients with symptomatic knee osteoarthritis (OA). 4-year outcomes for six measures (KOOS Pain, Symptom, Quality of Life, and Function scores, 20-m walk pace, and chair stand time) were used to create six multiple linear regression models. Primary predictors were baseline minimum JSW and 4-year change in JSW measured from fixed flexion radiographs. Age, gender, body mass index (BMI), race, knee alignment, and baseline measures of the outcomes of interest were covariates. RESULTS: Lower baseline minimum JSW and a greater decrease in 4-year JSW significantly correlated with worse 4-year KOOS Pain, Symptom, and Quality of Life. With all other factors constant, a 4.1, 4.8, and 5.6 mm lower baseline JSW correlated with a clinically significant eight-point drop in 4-year KOOS Pain, Symptom, and Quality of Life scores respectively. Additionally, a 3.5, 3.1, and 4.0 mm loss of JSW over 4 years correlated with a clinically significant eight-point drop in 4-year KOOS Pain, Symptom, and Quality of Life scores respectively. CONCLUSIONS: Our results indicate quantitative radiographic JSW measurements correlate with 4-year clinical outcomes. Since patients with narrower JSW at the onset of study had lower KOOS scores at 4 years even after controlling for 4-year change in JSW and baseline KOOS scores, clinical outcomes in knee OA may be predetermined once the disease process begins. These findings suggest early treatment with disease modifying therapies may be necessary to influence outcomes.

Factors affecting paramagnetic contrast enhancement in synovial fluid: effects of electrolytes, protein concentrations, and temperature on water proton relaxivities from Mn ions and Gd chelated contrast agents.

INTRODUCTION: Protein and electrolyte concentration of synovial fluid (SF) varies with the type of underlying arthritis. These characteristics can be utilized by magnetic resonance technology to provide a potentially significant diagnostic modality through quantitative assessments of inherent water relaxation rates and their response to contrast agents. METHODS: We evaluated the effect of a classic "in vitro" contrast agent, the Mn ion, and a common "in vivo" gadolinium based contrast agent, gadopentetate dimeglumine, on the water relaxation times of solutions with biochemical compositions simulating different types of arthritis along with similar studies of SF obtained from patients. RESULTS: The results demonstrate how protein and electrolyte concentrations play a significant role in the response of water relaxation to the Mn ion but much less so to chelated gadolinium contrast agents used clinically. DISCUSSION: A major challenge remains to develop paramagnetic agents with less toxicity than the Mn ion but with similar properties that can then serve as a tool to determine protein concentrations through imaging and thereby assist in the diagnosis of inflammatory arthrides and evaluation of therapeutic regimens.

Computed tomography in the evaluation of arthritis.

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.

Pigmented villonodular synovitis.

Pigmented villonodular synovitis is a benign proliferative disorder of the synovium of uncertain cause. It may involve tendon sheaths, bursae, or joints, the latter occurring as diffuse involvement or a localized nodule. This article reviews the clinical features of the disorder and the imaging features of the disease, concentrating on the findings and utility of MR imaging.

Magnetic resonance imaging of rheumatoid arthritis.

MR imaging is able to demonstrate both the structural changes that occur in rheumatoid arthritis and the inflammatory changes, including synovial proliferation and joint effusion. MR imaging can demonstrate erosion before it is visible on radiographs. Although MR imaging appears to be very helpful in assessing the severity of rheumatoid arthritis and its response to therapy, the optimal technique for this assessment and the ultimate clinical value of MR imaging have yet to be determined.

Dynamic lateral patellar tilt in the anterior cruciate ligament-deficient knee. A magnetic resonance imaging analysis.

An open-configuration magnetic resonance imaging scanner was used to document patellar tracking abnormalities in 11 anterior cruciate ligament-injured knees. The contralateral normal knees were used as controls. Images were obtained with the quadriceps muscles at rest (knee flexion at 40 degrees, 25 degrees, and 10 degrees) and with the quadriceps muscles contracted (knee flexion at 40 degrees and 25 degrees). When the quadriceps muscles were at rest there were no differences in patellar alignment between the anterior cruciate ligament-injured knees and the contralateral normal knees. When the quadriceps muscles were maximally contracted at 40 degrees of flexion, the patellae of the anterior cruciate ligament-injured knees tilted laterally 3.6 degrees relative to the resting state. When the quadriceps muscles were contracted at 25 degrees of flexion, the patellae of the anterior cruciate ligament-injured knees tilted laterally approximately 4 degrees relative to the resting state. Quadriceps-active lateral patellar tilt at 25 degrees of flexion was greater in the anterior cruciate ligament-injured knees than in the contralateral normal knees, and it correlated with instrumented measurements of anterior tibial translation. Dynamic lateral patellar tilt during open kinetic chain exercises and during other activities that produce anterior tibial translation may contribute to extensor mechanism dysfunction in the anterior cruciate ligament-injured knee.

Magnetic resonance imaging of arthritides affecting the shoulder.

MR imaging has thus far had a limited role in the evaluation of arthritis involving the shoulder. In certain cases, such as in amyloid and synovial osteo chondromatosis, however, MR imaging may be virtually diagnostic. It is likely that MR imaging will have an expanded role in the evaluation of arthritis in the future.

Magnetic resonance imaging of autologous chondrocyte implantation.

There is now over 10 years experience with autologous chondrocyte implantation (ACI) for the management of full-thickness chondral injuries in the knee. This article briefly reviews the surgical procedure, the time lines of graft maturation, and patient rehabilitation in the context of postoperative magnetic resonance imaging (MRI) assessment. The normal and abnormal appearances of ACI repair cartilage on MR images are described, with an emphasis on the MR appearances of the complications that may occur after this procedure, and the usefulness of MR imaging for the surgeon.

Outcomes after a single-stage procedure for cell-based cartilage repair: a prospective clinical safety trial with 2-year follow-up.

BACKGROUND: There are currently several approaches being pursued to treat focal defects of articular cartilage, each having specific advantages or challenges. A single-stage procedure that uses autologous cartilage fragments, Cartilage Autograft Implantation System (CAIS), is being evaluated in patients and may offer a clinically effective option. PURPOSE: To establish the safety of CAIS and to test whether CAIS improves quality of life by using standardized outcomes assessment tools. STUDY DESIGN: Randomized controlled trial; Level of evidence, 2. METHODS: Patients (n = 29) were randomized (1:2) with the intent to treat with either a control (microfracture [MFX]) or an experimental (CAIS) procedure. Patients were followed at predetermined time points for 2 years using several standardized outcomes assessment tools (SF-36, International Knee Documentation Committee [IKDC], Knee injury and Osteoarthritis Outcome Score [KOOS]). Magnetic resonance imaging was performed at baseline, 3 weeks, and 6, 12, and 24 months. RESULTS: Lesion size and International Cartilage Repair Society (ICRS) grade were similar in both groups. General outcome measures (eg, physical component score of the SF-36) indicated an overall improvement in both groups, and no differences in the number of adverse effects were noted in comparisons between the CAIS and MFX groups. The IKDC score of the CAIS group was significantly higher (73.9 ± 14.72 at 12 months and 82.95 ± 14.88 at 24 months) compared with the MFX group (57.78 ± 18.31 at 12 months and 59.5 ± 13.44 at 24 months). Select subdomains (4/5) in the KOOS instrument were significantly different at 12 and 18 months, and all subdomains (Symptoms and Stiffness, Pain, Activities of Daily Living, Sports and Recreation, Knee-related Quality of Life) were significantly increased at 24 months in CAIS with scores of 88.47 ± 11.68, 90.64 ± 7.87, 97.29 ± 3.8, 78.16 ± 22.06, and 69 ± 23.15 compared with 75 ± 9.31, 78.94 ± 13.73, 89.46 ± 8.13, 51.67 ± 26.01, and 37.15 ± 21.67 in the MFX group. These significant improvements were maintained at 24 months in both IKDC and KOOS. Qualitative analysis of the imaging data did not note differences between the 2 groups in fill of the graft bed, tissue integration, or presence of subchondral cysts. Patients treated with MFX had a significantly higher incidence of intralesional osteophyte formation (54% and 70% of total number of lesions treated) at 6 and 12 months when compared with CAIS (8% and 25% of total number of lesions treated). CONCLUSION: The first clinical experience in using CAIS for treating patients with focal chondral defects indicates that it is a safe, feasible, and effective method that may improve long-term clinical outcomes.

Targeted dendrimer-based contrast agents for articular cartilage assessment by MR imaging.

OBJECTIVE: Magnetic resonance (MR) imaging with contrast media has shown promise for articular cartilage assessment. Dendrimer-linked nitroxides, a new family of MR contrast agents targeted to glycosaminoglycan, may improve cartilage evaluation. This study is designed to determine the ability of dendrimer-linked nitroxides to enhance articular cartilage and measure the intra-articular life-time of these agents. DESIGN: Cartilage T(1) was evaluated using immature bovine patella in solutions of five different dendrimer-linked nitroxides, saline or Gd-DTPA at 1.5T. The "relaxivity per dose" (change in cartilage 1/T(1) produced by a given concentration of agent) was calculated. The half-life of joint fluid enhancement was measured at 2T after solutions of three dendrimer-linked nitroxides, Gd-DTPA, and saline were injected into rabbit stifle joints. Twenty-four hours after injection, the joints were examined grossly and by histology for toxicity. RESULTS: All but the largest dendrimer-linked nitroxide were able to intensely enhance articular cartilage on MR. Relaxivity per dose measurements were between 3.5 and 68 times greater than Gd-DTPA. The largest nitroxide appeared to be excluded from articular cartilage. Intra-articular half-lives of the dendrimer-linked nitroxides were sufficiently long (160-208 min) for in vivo MR imaging to be performed. Histological assessments of joints showed minimal synovial inflammatory and necrosis scores 1 day post-injection that were similar for all agents, including Gd-DTPA. CONCLUSION: Dendrimer-linked nitroxides strongly enhance cartilage and are promising as articular cartilage-specific MR contrast agents. The intra-articular life-time is sufficient for imaging studies and, in initial evaluation, the agents exhibit minimal toxicity in rabbit joints.

Prevalence of labral tears and cartilage loss in patients with mechanical symptoms of the hip: evaluation using MR arthrography.

OBJECTIVE: To determine the prevalence of labral tears and cartilage lesions in patients with mechanical symptoms of the hip using magnetic resonance (MR) arthrography. METHODS: A total of 100 patients with mechanical symptoms of the hip such as pain, clicking, locking and giving way underwent MR arthrography of the hip to rule out a labral tear. Hip joints were evaluated for labral alterations, bone marrow edema (BME), and other pathology using a novel semi-quantitative scoring system. Cartilage changes were graded separately for the acetabulum and femoral head in the anterior, posterior, central, medial, and lateral hip joint regions (10 locations) on a 6-point scale: 0=normal; 1=signal heterogeneity; 2=fissuring, 3=thinning <50% of the normal thickness; 4=thinning >50% of the normal thickness; 5=full thickness cartilage loss. Labral tears were categorized into normal, intrasubstance degeneration, simple tear or complex tear with two or more tear regions. Statistical methods were contingency tables, Fisher's exact test for discrete outcomes (based on grade scores), Spearman's rank correlation (r) and t tests for continuous outcomes, using pooled and stratified analyses. RESULTS: On MR arthrography, labral tears were found in 66 patients (66% prevalence) with 13 having more than one location involved. Locations were 19 lateral (13 simple, six complex), 54 anterior (39 simple, 15 complex), eight posterior (six simple, two complex). Cartilage lesions were found in 76 patients (76% prevalence) with 53 demonstrating involvement of more than one compartment. The most common finding was cartilage thinning <50% in 99 regions in 44 patients. Cartilage thinning >50% was shown in 34 patients in 67 areas. When we correlated the grade of cartilage abnormality with the grade of labral tear, we found a statistically significant correlation (r=0.29; P< or =0.01). The size of cartilage abnormality was correlated with the grade of labral tear in the lateral acetabulum (r=0.38; P<0.001), anterior acetabulum (r=0.22; P< or =0.002), and lateral femoral head (r=0.29; P< or =0.004). The grade of cartilage loss was correlated with the grade of BME (r=0.44; P< or =0.001). CONCLUSION: Labral tears and cartilage loss are common in patients with mechanical symptoms in the hip. Cartilage loss, labral tears and BME appear interrelated and may represent important risk factors that may affect the development and progression of osteoarthritis in the hip joint.

Use of a novel percutaneous biopsy localization device: initial musculoskeletal experience.

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.