Treatment of collagen induced arthritis by proteolytic enzymes: immunomodulatory and disease modifying effects.

OBJECTIVE: To investigate the efficacy of a novel therapy (proteases) in an animal model of rheumatoid arthritis, and to investigate the mechanisms of arthritogenesis. METHODS: We induced progressive arthritis in male DBA/1 mice by immunization and boosting with Type II collagen; groups of mice were treated orally twice daily with either ibuprofen or proteases, or were left untreated. After 2 weeks, joints were scored for clinical, radiographic, and histologic changes. In addition, we measured serum levels of IgG anti-collagen II, the glycosylation of circulating total and anti-collagen II IgG, and cytokine production by lymphocytes isolated from lymph nodes. RESULTS: Amelioration of joint inflammation, and accentuation of a prototypical Th2 cytokine (interleukin 5) were similar in the ibuprofen and protease treatment groups. However, protease treatment protects and preserves articular cartilage, normalizes the sialylation of IgG and anti-collagen antibody, and fully restores Th1 (interferon-gamma) synthesis, distinct from ibuprofen. CONCLUSION: Protease therapy has antiinflammatory efficacy in the early (inflammatory) phase of collagen induced arthritis, similar to ibuprofen. The immunomodulatory effects of proteases, not seen with ibuprofen, may underlie a correction of aberrant IgG glycosylation and/or contribute to the increased capacity of protease to delay or forestall erosive and destructive arthritis or ankylosis. Similar effects may apply to spontaneous RA in humans.

MR arthrography for evaluation of the acetabular labrum.

MR arthrography of the hip has provided new insights into the lesions underlying mechanical hip pain. Until now evaluation of these structures, especially the acetabular labrum, has been limited. With the joint distention provided by MR arthrography, labral detachments and intrasubstance tears can be identified and differentiated from the many varied appearances of the asymptomatic labrum. This article reviews the normal anatomy of the hip, the clinical presentation of internal derangement and the technique for performing MR arthrography. The variations in morphology and signal of the asymptomatic labrum are reviewed as well as the appearance of the abnormal labrum.

From the RSNA Refresher Courses. Radiological Society of North America. Chronic adult hip pain: MR arthrography of the hip.

This article describes the technique for performance and interpretation of magnetic resonance arthrography of the hip. A description of normal anatomy of the hip is presented, and the appearance of the abnormal labrum is discussed. Labral detachments and tears are the most common clinically significant abnormalities to be identified. These abnormalities are recognized on the basis of the presence of contrast material at the acetabular-labral interface or within the substance of the labrum. Many varied appearances of the labrum have been identified within the asymptomatic population, and the correlation of these appearances is contrasted with those of the abnormal labrum in symptomatic patients. To date, it is difficult to draw conclusions regarding the significance of an absent labrum or of a sulcus at the acetabular-labral junction. Experience suggests that an absent labrum in a symptomatic individual is pathologic and that a sulcus at the anterosuperior acetabular-labral junction may be a normal variant.

Morphologic considerations of C2 isthmus dimensions for the placement of transarticular screws.

STUDY DESIGN: This study examines the C2 vertebrae using both direct anatomic and computed tomographic measurements. OBJECTIVE: To define the relation of the C2 vertebrae bony elements to the vertebral artery and the spinal canal, to determine individuals at risk for vertebral artery injury during C1-C2 transarticular screw placement. SUMMARY OF BACKGROUND DATA: Recent literature assessing the safety of upper cervical spine transarticular screws has concentrated on technique, including the optimal point of entry and path projection of the screw. The actual dimensions of the C2 isthmus of the pars interarticularis has not been examined in a large number of specimens. METHODS: C2 isthmus width and height measurements were made on 205 human cadaveric C2 vertebrae. Vertebrae predicted to be at risk for vertebral arterial injury were imaged by computed tomography. RESULTS: There were 102 female and 103 male specimens with mean isthmus widths of 8.2 +/- 1.5 mm and 7.2 +/- 1.3 mm, respectively. Five specimens (2.4%) had an isthmus width less than 5 mm. The mean isthmus heights were 8.6 +/- 2.0 mm and 6.9 +/- 1.5 mm for male and female specimens, respectively. In twenty-four specimens (11.7%), one or both isthmi had a height of less than 5 mm. Six of these specimens were male and 18 were female. The right C2 isthmus was generally smaller than the left. Computed tomographic measurements closely approximated those of the actual dimensions of the isthmi. CONCLUSIONS: Placing a 3.5 mm screw in a patient with narrow C2 isthmus dimensions (smaller than 5 mm in either the height or width) is technically difficult. Because of narrow C2 isthmus width and/or height, approximately 10% of patients may be at risk for a vertebral artery injury with placement of C1-C2 transarticular screws.

Evaluation of the postoperative spine: reducing hardware artifacts during magnetic resonance imaging.

The magnetic susceptibility artifact created by the hardware that is a mainstay of today's surgical techniques can complicate magnetic resonance (MR) imaging of the postoperative spine. This article reviews the physical principles that underlie production of the magnetic susceptibility artifact, as well as the imaging parameters that can be altered to reduce artifact and improve visualization of the areas of concern. Those imaging parameters that most greatly affect artifact production are the strength of the ambient magnetic field, the type of sequence chosen, echo time, the strength and orientation of the frequency encoding gradient, the resolution along the frequency encoding axis as determined by field of view (FOV) and the number of pixels in the frequency encoding direction, the orientation of the hardware to the main magnetic field, the section thickness, and the orientation of the imaging plane.

MR imaging of the traumatized lumbar spine.

MR imaging is the imaging modality of choice for evaluation of the traumatized lumbar spine, providing critical information for determination of appropriate therapy. It is superior to other modalities for evaluating the supporting ligaments, disc, spinal cord, and the cauda equina. Major fracture patterns are readily discernable. Canal compromise caused by osseous fragments, epidural hemorrhage, or disc fragments is well visualized.

Augmentation of spinal arthrodesis with autologous bone marrow in a rabbit posterolateral spine fusion model.

STUDY DESIGN: Posterolateral spinal fusion with autologous bone marrow aspirate in addition to autograft iliac crest bone graft in a rabbit model. OBJECTIVE: To demonstrate that the addition of autologous bone marrow can have positive effects on bone formation and spinal fusion. SUMMARY OF BACKGROUND DATA: Bone marrow has been shown to contain osteoprogenitor cells. A number of studies have demonstrated that bone formation is possible with autologous marrow injection into orthotopic sites such as that performed in femur fracture models. METHODS: A bone paucity model of posterolateral spine fusion was developed. The control animals received 0.8 g of morselized autogenous iliac crest bone graft harvested from a single iliac crest. The graft was mixed with 2 mL of clotted peripheral blood. In the experimental group, 2 mL of bone marrow aspirated from the opposite iliac crest was substituted for the peripheral blood clot. All rabbits were killed at 12 weeks, and the specimens were subjected to evaluation by posteroanterior radiography for the presence of fusion, computed tomography for bone volume, and biomechanical testing for stiffness. RESULTS: Successful fusion was achieved in 61% of the animals in the experimental group versus 25% in the control group (P < 0.05). The fusion mass in the experimental group had a mean volume of 919 +/- 387 mm3 versus 667 +/- 512 mm3 for the control group, as measured from computed tomography images. The results of the biomechanical testing validated the radiographic scoring system. The stiffness in specimens, graded as having a radiographic score of 4, was significantly greater than in specimens with radiographic scores of 1 and 2. CONCLUSION: In cases for which an adequate quantity of autogenous bone graft is not available, addition of bone marrow may facilitate greater bone formation and successful fusion.

Interactive MR imaging-guided biopsy and aspiration with a modified clinical C-arm system.

OBJECTIVE: This investigation was performed to test the hypotheses that interactive guidance of MR image acquisition during needle-directed procedures using a clinical 0.2-T C-arm open MR imaging system integrated with a frameless optically linked stereotaxy system is feasible, and that procedure times can be sufficiently short to be well tolerated by the patient. SUBJECTS AND METHODS: One hundred six MR-guided procedures were performed in 86 patients (ranging in age from 5 months to 88 years) using a clinical C-arm imaging system supplemented with an in-room RF-shielded liquid crystal display monitor, a frameless stereotaxy system, rapid gradient-echo sequences for needle guidance, and MR-compatible monitoring and surgical lighting equipment. We performed 50 biopsies and aspirations of the head and neck in 37 patients, 23 biopsies of musculoskeletal lesions in 22 patients, 16 biopsies of abdominal sites in 10 patients, six biopsies of the thoracolumbar spine or sacrum in six patients, and 11 shoulder joint injections for MR arthrography in 11 patients, in addition to 38 MR arthrographic injections on the same imaging system described in a previous report. Tissue sampling included fine-needle aspiration (n = 90) and cutting needle core biopsy (n = 41). Thirty-five patients underwent both procedures. Procedures were evaluated for success of needle placement, procedure time, and complications. RESULTS: Needle placement was successful in all cases, and no complications occurred. Tissue was sufficient for pathologic diagnosis for all but eight patients. Passes per patient averaged 2.1. For fine-needle aspiration, instrument time averaged 7 min 42 sec per pass, cutting needle core biopsy averaged 6 min 24 sec, and shoulder injection averaged 8 min. CONCLUSION: MR imaging guidance for needle procedures on a clinical 0.2-T C-arm system with supplemental interventional accessories is feasible, with relatively rapid needle placement.

CT-guided fine needle aspiration and needle core biopsy of skeletal lesions. Complementary diagnostic techniques.

OBJECTIVE: To compare the diagnostic sensitivity and specificity of fine needle aspiration (FNA) to those of needle core biopsy (NCB) and to attempt to determine if a complementary role exists for the two modalities. STUDY DESIGN: Skeletal lesions in 144 patients were evaluated with concomitant FNA and NCB over a 21-year period. FNAs and NCBs were divided as diagnostic of neoplasm, normal or inflammatory (i.e., osteomyelitis), or unsatisfactory. The results of each modality were then reviewed and compared. RESULTS: In the 144 total cases, a diagnosis was possible in 79% (114) cases. FNA and NCB concurred in 73% (83) of diagnostic cases. Concurrence was 87% between diagnostic FNA (83) and NCB (95). The two modalities agreed in 78% of cases diagnosed as metastatic carcinoma and in 59% of primary malignant tumors of bone (17) (excluding Ewing's sarcoma). FNA alone was diagnostic in 8% (9) of cases, including 5 metastatic carcinomas, 2 chondrosarcomas, 1 Ewing's sarcoma and 1 case of osteomyelitis. This represented 24% of the 38 cases in which NCB was unsatisfactory (11) or normal (27). NCB alone was diagnostic in 19% (22) of cases, including 11 metastatic carcinomas, 3 osteosarcomas, 1 chondrosarcoma, 1 spindle cell sarcoma (not otherwise specified), 1 Ewing's sarcoma, 2 capillary hemangiomas and 3 cases of osteomyelitis. This represented 43% of the 51 cases in which FNA was misinterpreted (2), unsatisfactory (33) or normal (16). NCB more specifically typed a metastatic lesion or suggested a primary focus in 21% (12) of the 58 cases in agreement. It also more specifically subtyped 50% (5) of the 10 primary malignant tumors of bone. CONCLUSION: Given these findings, NCB is more specific in the evaluation, grading and typing of skeletal lesions in particular malignant primary bone tumors. Overall, there is excellent agreement between FNA and NCB, especially in the evaluation of benign primary bone tumors. Most important, FNA improved the diagnostic yield in 24% of cases when NCB was normal or unsatisfactory, obviating the need for rebiopsy. FNA should be performed concurrently with NCB in the evaluation of skeletal lesions since the two modalities are complementary.

Cortical metastatic lesions of the appendicular skeleton from tumors of known primary origin.

BACKGROUND AND OBJECTIVES: Metastatic disease represents the most common neoplastic process involving bone. Recently, a small subset of cortical based metastatic lesions has been identified. We attempted to delineate the incidence, origin, location, and possible significance of these lesions within an orthopaedic patient population. METHODS: A chart and radiographic review of patients treated for metastatic disease to bone over a 17-year period was performed. Inclusion criteria for lesions were as follows: 1) an appendicular skeletal site, 2) histopathologic confirmation of origin, and 3) presence within a patient diagnosed with a single, known neoplastic process. The lesions were classified as either cortical or medullary based. RESULTS: Eighty-three lesions (70 patients) satisfied inclusion criteria. Most lesions were of pulmonary (26), breast (22), renal (16), or prostatic (8) tumor origin. Eighteen lesions (22%) from 15 patients were identified as cortical and represented initial presentation in 7 patients. These lesions were of pulmonary (11), renal (5), and breast (2) tumor origin. CONCLUSIONS: Cortical based metastases within the appendicular skeleton may occur more frequently than previously expected. While tumors of pulmonary and renal origin accounted for 42 of the 83 (51%) appendicular lesions, they were responsible for 16 of the 18 (89%) cortical metastases. This preponderance of pulmonary and renal metastases to the cortex is consistent with previously published reports. Our findings may be of value when diagnosing and treating patients whose initial presentation is a cortically based lesion.

Remember true FISP? A high SNR, near 1-second imaging method for T2-like contrast in interventional MRI at .2 T.

Clinical requirements for interventional MRI (I-MRI) monitoring of needle placement or thermal ablation demand rapid (near-real-time) image acquisition rates, high spatial resolution, and T2 weighting. Experimental analysis performed earlier suggests that many sequences used for either rapid scanning or T2 weighting at high fields fail to meet both the speed (conventional spin echo [SE], turbo SE) or contrast (ie, fast low-angle shot [FLASH], fast imaging with steady state precession [FISP]) requirements when used at .2 T. In this work, we revisited a number of pulse sequences advocated primarily for higher field applications requiring T2 weighting and found that refocused steady state coherent pulse sequences, aka, true FISP sequences, performed superiorly in achieving both speed and T2 contrast requirements for I-MRI at .2 T. This work focuses on our experience with this new/old technique in the I-MRI setting and describes how one can take advantage of the low field strength and modest inhomogeneity of .2 T (and similar) systems to design pulse sequences that balance TE, TR (and hence T2 dephasing), and resonant offset frequency effects to provide images with the desired contrast and minimal artifactual field inhomogeneity "banding." At high flip angles (approximately 90 degrees ), reasonably short TEs (approximately 5 msec) and short TRs (approximately 10 msec), we have used this method in our last 25 I-MRI procedures (biopsies and/or radiofrequency [RF] thermal ablations) and found these sequences to be extremely useful in both needle localization phases of I-MRI biopsy procedures, RF thermal ablation electrode guidance, and posttherapy imaging assessment. Design methods and clinical I-MRI cases are presented that highlight these points.

Accuracy of using computed tomography to identify pedicle screw placement in cadaveric human lumbar spine.

STUDY DESIGN: Utility of using computed tomography to predict pedicle screw misplacement. OBJECTIVE: This study defines the sensitivity and specificity of predicting pedicle screw placement by experienced clinicians using a CT scan image. SUMMARY OF BACKGROUND DATA: In clinical and research settings, the method most commonly used to evaluate pedicle screws placement has been computed tomography. However, no current literature describes the accuracy of this method of evaluating screw placement. METHOD: Cobalt-chrome and titanium alloy pedicle screws of identical size were placed in six cadaveric human lumbar spine. Wide laminectomy was performed to allow complete visualization of the pedicles. Three consecutive lumbar levels were instrumented in each spine, giving 36 pedicle screw placements to identify. The instrumented spines were imaged, and four orthopaedic spine surgeons and a musculoskeletal radiologist were asked to read the images to identify the accuracy of screw placement within the pedicles. RESULTS: The sensitivity rate of identifying a misplaced screw was 67 +/- 6% for cobalt-chrome screws compared with 86 +/- 5% for titanium screws (P < 0.005). The specificity rates of radiographic diagnosis of misplaced pedicle screws were 66 +/- 10% for cobalt-chrome screws and 88 +/- 8% for titanium screws (P < 0.005). Similarly, a statistically significant difference was found in the sensitivity rates of identifying screws placed correctly in the pedicle: 70 +/- 10% for cobalt-chrome screws versus 89 +/- 8% for titanium screws (P < 0.005). Overall accuracy rates were 68 +/- 7% for cobalt chrome screws versus 87 +/- 3% for titanium screws (P < 0.002). CONCLUSION: Reliance on the computed tomography scan data alone in determining accuracy of pedicle screws can lead to inaccuracies in both clinical and research conditions.

MR arthrography of the shoulder: rethinking traditional imaging procedures to meet the technical requirements of MR imaging guidance.

OBJECTIVE: The purpose of this study was to determine the feasibility of and the appropriate technique for performance of MR imaging-guided arthrography of the shoulder. SUBJECTS AND METHODS: Thirty-eight MR imaging-guided glenohumeral joint punctures were performed using an open C-arm scanner with a vertically oriented magnetic field, adapted for interventional procedures. Two different approaches to the shoulder were used: a modification of the traditional anterior approach (seven procedures), and an anterosuperior approach (31 procedures) mimicking the anterior arthroscopy portal. The average procedure duration was determined. A retrospective review of needle mediolateral and anterioposterior position was determined for the anterosuperior approaches. RESULTS: Average procedure duration was 21 min for the anterior approach and 12 min for the anterosuperior approach. Subjectively, needle conspicuity was minimal with the anterior approach, contributing to prolonged imaging times. Needle visualization was much improved with the anterosuperior approach. Nine of the 31 anterosuperior procedures involved inadvertent injection of the subacromial or subdeltoid bursa. At the time of retrospective review, the needle was too laterally or too anteriorly positioned in six of these nine patients. CONCLUSION: With consideration of the technical demands of MR imaging guidance for interventional procedures, MR imaging-guided arthrography of the shoulder is feasible. The traditional radiologic approach to the shoulder must be modified to provide adequate visualization of the needle. The anterosuperior approach meets this needs.

Normal regional anatomy of the shoulder.

The shoulder is a remarkable structure enjoying a greater range of motion than any other articulation in the human body. The shoulder is not a single joint but actually four separate articulations that act synergistically. The authors review the complex anatomy of the shoulder, presenting correlation between anatomic sections and MR arthrography.

Current concepts of MR arthrography of the hip.

MR arthrography is a recent addition to the imaging evaluation of the hip. The combination of joint distention and multiplanar imaging provides a detailed assessment of the intraarticular structures, most importantly the acetabular labrum. An acetabular labral tear is a potential cause of hip pain in patients with an otherwise normal joint, or patients with underlying pathology such as developmental dysplasia. A summary of the current concepts regarding identification of labral degeneration, labral tears and detachments, and potential pitfalls is presented in this article.