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ABSTRACT |
Thursday, May 4, 10:00 AM-12:00 PM
Abstracts 208-217
Moderators: Laura W. Bancroft, MD and Kirkland W. Davis, MD
10:00 AM
Keynote Address: Update on Femoroacetabular Impingement
Laura W. Bancroft, MD, Mayo Clinic, Jacksonville, FL
10:20 AM
208. The Raised Eyebrow Sign: A Simple Method for Identifying Subtle Hip Dysplasia
Durkee N.J.1; Richardson M.L.1*; Hunter J.C.2; 1. Department of Radiology, University of Washington, Seattle, WA; 2. Department of Radiology, University of California, Davis, Sacramento, CA.
Address correspondence to M.L. Richardson (mrich{at}u.washington.edu)
Objective: To evaluate the clinical utility and relevance of an easily recognized imaging finding on AP plain radiographs of the pelvis in identifying patients with subtle hip dysplasia.
Materials and Methods: A retrospective review of 290 consecutive AP plain radiographs of the pelvis. The center edge angle of each hip was measured. Each hip was also assessed for the presence of the "raised eyebrow (John Belushi) sign". Statistical analysis was used to assess the association between the presence of this sign and the presence of hip dysplasia.
Results: The "raised eyebrow sign" was found in 52 of the 580 hips reviewed. Forty-three of the 52 hips with this sign had a center edge angle consistent with dysplasia. An exact permutation test showed a highly statistically significant association between this sign and the presence of hip dysplasia (p = 0.0000). A patient with this sign is over 500 times more likely to have hip dysplasia than a patient without this sign.
Conclusion: The raised eyebrow sign is a simple method to identify patients with hip dysplasia. If this sign is present, it should prompt measurement of the center angle to confirm the diagnosis.
209. Imaging Findings Suggestive of Femoro-Acetabular Impingement in Patients Diagnosed with Impingement Syndrome Confirmed by Arthroscopy
Galdino G.M.; Malfair D.*; Link T.M.; Safran M.; Steinbach L.S.; Radiology, University of California San Francisco, San Francisco, CA.
Address correspondence to D. Malfair (david.malfair{at}radiology.ucsf.edu)
Objective: Purpose: To determine the prevalence of imaging findings in patients diagnosed with the clinical syndrome of femoro-acetabular impingement confirmed by arthroscopy, and to determine correlation with other arthroscopic findings.
Materials and Methods: Methods: Preoperative imaging studies of 20 patients diagnosed with the femoro-acetabular impingement were retrospectively reviewed by two radiologists to document the presence of imaging findings suggestive of impingement syndrome in the symptomatic hip. Imaging findings were recorded for radiographs and MRI studies in all patients. Alpha angles were calculated on plain radiographs and coronal/axial T1 weighted sequences on MRI. The prevalence of specific imaging findings was determined for the symptomatic hip by modality and correlated with findings at physical exam and arthroscopy.
Results: All patients were preoperatively diagnosed with femoro-acetabular impingement and demonstrated a positive impingement test with 82% exhibiting limited internal rotation. Femoro-acetabular impingement was confirmed by arthroscopy in all cases. Labral tear was diagnosed in all patients at arthroscopy. Osteoarthritis was diagnosed preoperatively and confirmed by arthroscopy in 20% of cases. The most prevalent radiographic finding of impingement was presence of a femoral head/neck bump (92%), followed by acetabular ossicles (62%), inferior osteophyte (31%) and joint space narrowing (31%). Alpha angle in symptomatic versus contralateral hips averaged 87 vs. 73 degrees, respectively (p < 0.05). The most prevalent finding of impingement on MRI was femoral/neck bump (67%) with adjacent cysts (25%), and local bone marrow edema (17%). Bone marrow edema was also found in other regions of the hip joint (25%). Antero-lateral labral tears were diagnosed in 67% of cases and labral osseous cysts were found in 42%. Average alpha angle in coronal/axial orientation in the effected hip was 71/76 degrees respectively, significantly higher than in the contralateral asymptomatic hip (p < 0.05).
Conclusion: The presence of a femoral head/neck bump on radiographs and MRI as well as labral tears visualized on MRI in patients with confirmed femoro-acetabular impingement were the most prevalent findings. Other associated findings were substantially less frequent.
210. The Painful Iliopsoas Tendon: Snapping Tendon versus Iliopsoas Friction Syndrome
Blankenbaker D.G.1*; De Smet A.A.1; Keene J.S.2; 1. Department of Radiology, University of Wisconsin Medical School, Madison, WI; 2. Department of Orthopedic Surgery and Rehabilitation, University of Wisconsin Medical School, Madison, WI.
Address correspondence to D.G. Blankenbaker (dg.blankenbaker{at}hosp.wisc.edu)
Objective: Painful snapping hips can be due to external, intra-articular or internal causes such as a snapping iliopsoas tendon. Sonography is the preferred imaging modality to dynamically evaluate for a snapping iliopsoas tendon. Recently, iliopsoas friction syndrome has been proposed as another cause of a painful snapping hip. We reviewed our experience with sonographic evaluation of the iliopsoas tendon in 40 patients with the clinical diagnosis of a painful internal snapping hip. Our goal was to evaluate the relationship between static and dynamic sonography of the iliopsoas tendon and subsequent pain relief after injection of anesthetic into the iliopsoas bursa.
Materials and Methods: Static and dynamic sonography of the iliopsoas tendon was performed in 15 male and 25 female patients (mean age 36 years) followed by sonographically guided injection of their iliopsoas bursa with 3.5 ml of 1% Lidocaine and 3.5 ml 0.5% Bupivacaine. The patients' hip pain was assessed prior to and two days following the anesthetic injection. We then determined the relationship between their sonographic findings and their pain relief.
Results: Thirty-eight of the 40 patients had normal static sonography of the iliopsoas tendon; one had iliopsoas bursitis and one had iliopsoas tendinosis. Color Doppler imaging showed increased intratendinous or peritendinous blood flow in 3 of the 23 patients in whom it was performed. Nine of 40 patients had snapping of the iliopsoas tendon documented at sonography. Of these 9 patients, 7 had complete, 1 had partial, and 1 had no pain relief following anesthetic injection of their iliopsoas bursa. However, 21 of the 40 patients without a sonographically documented snapping of the iliopsoas tendon had complete or partial pain relief following anesthetic bursal injection.
Conclusion: We found that 89 % of patients with a sonographically documented snapping iliopsoas tendon got pain relief after anesthetic injection of their iliopsoas bursa. However, 53% of the patients with painful internal snapping hips but without a sonographically documented snapping tendon, also got pain relief with the anesthetic bursal injection. We believe that these patients have iliopsoas friction syndrome. In these patients, anesthetic injection of their bursa is an important diagnostic test to establish the etiology of their hip pain.
211. MRI as a Problem-Solving Tool in Unexplained Failed Total Hip Replacement Following Conventional Assessment
Johnston C.*; Kerr J.; Ford S.; O'Byrne J.; Eustace S.; Radiology, Cappagh National Orthopedic Hospital, Dublin, Ireland.
Address correspondence to C. Johnston (ciaranjohnston{at}yahoo.co.uk)
Objective: To evaluate MRI as a problem solving tool in patients with an unexplained failed total hip replacement following conventional radiological assessment.
Materials and Methods: 28 patients with an unexplained failed total hip replacement following conventional radiological assessment underwent additional MR imaging with an optimized turbo spin echo sequence. Images were reviewed by consensus and compared to gold standard diagnosis established by clinical follow up or following intervention when undertaken.
Results: Of 28 patients, MRI revealed an unsuspected diagnosis explaining the cause of prosthesis failure in 15 patients. In 8 of 15 in this group subsequent minimally invasive intervention obviated the need for revision total hip replacement. No cause for prosthesis failure was identified in 13 patients.
Conclusion: MRI may be safely and successfully undertaken in patients following total hip replacement and when undertaken frequently leads to an unsuspected diagnosis allowing informed patient management. In this study it allowed the identification of an unsuspected diagnosis in over 50% of cases.
212. Insufficiency Fractures of the Pelvis and Proximal Femur: Preferred Imaging Modality, Common Clinical Scenarios, and Typical Morphology
Ambekar A.*; Link T.M.; Steinbach L.; Radiology, University of California, San Francisco, San Francisco, CA.
Address correspondence to A. Ambekar (Avanti.Ambekar{at}radiology.ucsf.edu)
Objective: To assess epidemiological characteristics of pelvic and femoral insufficiency fractures; to analyze their location and morphology; and to compare CT and MRI in their diagnostic performance for fracture assessment.
Materials and Methods: The patient population consisted of 126 females (mean age 65.0+/-17.4) and 43 males (mean age 59.2+/-18.8) with insufficiency fractures. In all patients, MRI was performed, with additional CT in a subset (n = 20). Epidemiology of the patient population, including history of prior external beam radiation therapy, chemotherapy, previous steroid therapy, and other osteoporosis risk factors was recorded. MRI and CT exams were analyzed in consensus by two radiologists concerning the number and location of fractures, their morphology, related soft tissue findings, and concomitant bone pathology, with comparison of diagnostic performance. Follow-up exam or biopsy was performed in all patients to exclude pathologic fractures due to malignancy.
Results: In 169 patients, 211 fractures were diagnosed: 106 in the sacrum, 32 in the proximal femur, 29 in the pubis, 13 in the lumbar spine, 23 in the acetabulum, and 8 in the iliac bone. Two concomitant fracture sites were observed in 35 patients and three in 10 patients. Fractures occurred in distinct combinations: 19/29 pubic fractures occurred with sacral fractures and 11/23 acetabular occurred with proximal femur fractures. Isolated fractures usually occurred in the sacrum. Fifty patients had a history of pelvic radiation therapy and 82 patients had a history of malignancy. Only 14/169 patients reported a history of trauma. In 5 patients, concurrent avascular necrosis was found. CT performed within 30 days of MRI depicted the fractures in almost all cases, with occasionally improved detection of subtle fracture lines. MR improved the ability to classify fracture acuity with assessment of bone marrow edema.
Conclusion: Insufficiency fractures frequently occurred in older female patients, particularly after pelvic radiation. Fractures were often found at multiple sites in the pelvis. CT and MRI performed similarly well in diagnosis of fractures. CT improved visualization of fracture extent, while MR improved determination of fracture acuity.
213. Marrow Edema in the Medial Basicervical Femoral Neck: A Characteristic MR Finding of Stress Reaction in Women
Desai N.R.*; Math K.R.*; Katz D.S.; Rackson M.E.; Petchprapa C.N.; Irish R.D.; Department of Radiology, Beth Israel Medical Center, New York, NY.
Address correspondence to N.R. Desai (nealdesai77{at}yahoo.com)
Objective: To evaluate the demographics, location, and morphology of marrow edema in the medial basicervical femoral neck on MRI and its relation to stress reaction.
Materials and Methods: Of 1786 hip MR examinations performed at our institution over a 2 year period, 55 had bone marrow edema in the femoral neck. Exclusion criteria included acute injury, osteonecrosis and arthropathy of the hip. The 25 remaining studies (23 patients) were evaluated with respect to the location, morphology, size and extent of the bone marrow edema and the presence of a fracture line, adjacent periosteal reaction, or adjacent soft tissue edema. Available patient histories were reviewed to determine if the patient was a running athlete.
Results: 23 of the studies were done on a 1.5T MR unit and the remaining 2 on a 0.3T open magnet. Mean age was 31.5 years (range 24-49, SD 7.1 years). 92% of the patients were women (23/25), and there were 13 right and 12 left hips. The location was basicervical in 24/25 hips (96%). Mean measurements of the area of bone marrow edema (craniocaudal x transverse x anteroposterior) = 2.6 cm x 1.4 cm x 1.4 cm. All regions of edema were adjacent to the medial cortex. Regarding morphology of the marrow edema, 20 (80%) had a geographic component, and 5 (20%) were poorly defined throughout. 18/25 (72%) of studies had edema confined to the femoral neck, while 7 extended into the lesser trochanter or intertrochanteric region. 10 patients (40%) had a discernible fracture line within the region of marrow edema (mean length 0.65 cm, SD 0.34 cm) located an average of 1.1 cm (SD 0.3) cephalad to the upper margin of the lesser trochanter. 5/25 (25%) had associated periosteal reaction, and 8/25 (32%) had adjacent soft tissue edema. Of the 21 patients with available history, 18 (86%) were running athletes.
Conclusion: Bone marrow edema in the medial basicervical femoral neck is a characteristic presentation of stress reaction in the hip and has a strong predilection for women who are running athletes. Knowledge of the typical location and often geographic morphology of the marrow edema will help avoid misdiagnosis as tumor and its detection should prompt a search for an often subtle fracture line.
214. MRI Evaluation of the Effect of Hyperbaric-oxygen-therapy on Avascular Necrosis of Femoral Head in SARS Patients
Hong N.*; Du X.K.; Jiang Q.S.; Radiology, Peking University People's Hospital, Beijing, China.
Address correspondence to N. Hong (hongnan{at}bjmu.edu.cn)
Objective: To evaluate the treatment outcome of hyperbaric-oxygen-therapy on avascular necrosis of the femoral heads in SARS patients.
Materials and Methods: 14 SARS patients (22 hips) were identified to have stage I avascular necrosis (AVN) of the femoral based on characteristic MR imaging and radiographic findings. All patients underwent MRI before hyperbaric oxygen (HBO) therapy. The HBO treatment comprised 5-6 daily sessions each week, up to a total of 82 sessions. Follow-up imaging was scheduled every 4 months. The minimum follow-up was 25 months.
Results: After about 2 years follow-up, none of the hips with AVN demonstrated evidence of complete resolution. 4 patients (6 hips) progressed to stage III AVN, other patients (10 patients, 16 hips) progressed to stage II AVN, and remained at this stage by the time of final follow-up examination. Among them, the extent of AVN lesion became smaller in only one patient, but developed to stage II AVN. 3 patients (1 at stage III, 2 at stage II) underwent bone grafting.
Conclusion: Hyperbaric-oxygen therapy is not effective in the treatment of stage I avascular necrosis of femoral head in SARS patients, which was contrary to the result of Reis ND et al.
215. Characterization of Musculoskeletal Lesions by Proton MR Spectroscopy: First Results at 3Tesla
Fayad L.M.1*; Jacobs M.A.1; Barker P.B.1; Eng J.1; Weber K.L.2; Bluemke D.A.1; 1. Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD; 2. Orthopaedic Surgery, Johns Hopkins Medical Institutions, Baltimore, MD.
Address correspondence to L.M. Fayad (lfayad1{at}jhmi.edu)
Objective: MRI is very sensitive for detection of musculoskeletal lesions, but specificity is limited. The purpose of this study was to determine the feasibility and value of proton MR spectroscopy (MRS) at 3T for characterizing musculoskeletal lesion composition and distinguishing benign from malignant lesions using the metabolite choline (Cho) as a marker of malignancy.
Materials and Methods: Patients (n = 10) with indeterminate musculoskeletal lesions underwent diagnostic MRI at 3T (Philips) with proton MRS. Indications for MRI were: 5 bone lesions (2 malignant, 3 benign) and 5 soft tissue abnormalities (1 malignant, 4 benign). Two-plane T1-weighted (TR/TE = 600/15) and T2-weighted (TR/TE = 3,000/100) imaging was acquired with single voxel (SV) proton MRS (TR/TE = 2,000/140, voxel size = 2 cc, slice thickness = 1 cm) on 8 patients, 5 with a transmit-receive flexible coil (FC) and 3 with the body coil (BC). Also, single slice multivoxel proton MRS (TR/TE = 2,000/144, voxel size = 1 cc, FOV = 10 cm, slice thickness = 1cm) was performed in 2 patients, (1 FC, 1 BC). For patients who underwent SV technique, the voxel was localized to the center of the lesion. For multivoxel technique, the single slice was localized to include the lesion and surrounding normal tis-sues or, in the case of prior surgery, the area of scar and surrounding signal abnormality. Cho signal (3.2 ppm) was measured in each voxel and expressed relative to background noise level as a signal-to-noise ratio (SNR), where noise was measured between 8.0 and 10.0 ppm. Results of MRS were correlated with histology and clinical outcome. Cho SNRs obtained from malignant tumors were compared with those obtained from benign areas.
Results: Excellent quality spectra were obtained for all patients. Malignant lesions were osteosarcoma, metastasis and Grade 1 sarcoma. In these patients, MRS demonstrated a Cho signal peak with Cho SNRs of 5.2 (BC), 4.8 (FC) and 18.7 (FC) respectively. Benign lesions were unicameral bone cyst, hemangioma, stress reaction and 4 patients with post-operative myocutaneous flaps/fibrosis and no evidence of tumor recurrence. In these patients, MRS demonstrated a negligible Cho SNR and the typical spectrum of muscle (4 cases of flap respectively). Only a large water peak existed within the bone cyst.
Conclusion: These preliminary results show that both SV and multivoxel proton MRS, performed at 3T, are feasible. Proton MRS is a potential non-invasive tool for characterizing lesion composition and malignant activity.
216. MR Imaging Protocols for Optimized Visualization of the Collagen Membrane used for Autologous Matrix-induced Chondrogenesis (AMIC®) in Cartilage Repair
Gellissen J.1*; Wendler N.O.2; Stoeckelhuber B.M.1; Schelzel M.1; Helmberger T.K.1; Behrens P.2; 1. Department of Radiology, University of Luebeck, Luebeck, Germany; 2. Department of Orthopaedic Surgery, University of Luebeck, Luebeck, Germany.
Address correspondence to J. Gellissen (gellissen{at}t-online.de)
Objective: To compare the performance of different MR pulse sequences for high-contrast and high-spatial-resolution-imaging of collagen matrices.
Materials and Methods: Chondral resection 2 cm in size was carried out resembling a grade- IV defect of a porcine femoral condyle. A bilayer matrix consisting of collagen I/III (Chondro-Gide®, Geistlich Biomaterials, Switzerland) was dissected and fixed with fibrin glue. MR-imaging was conducted using a 1.5T machine (Siemens, Germany). 27 pulse sequences were varied with regard to their main properties (T1- and T2-weighted spin-echo or gradient echo), mode of volumetric data acquisition (2D, 3D), image matrix, slice thickness (1.3-2 mm) and the choice of fat saturation techniques. Signal intensities were measured in the subchondral layer, collagen membrane, adjacent cartilage and fluid. Contrast-ratios were computed.
Results: Contrast-ratios of the matrix vs. adjacent fluid/subchondral layer were calculated with values 0.05-0.88±0.04 and 0.03-0.99±0.05 respectively. While highest contrast was achieved using PD-weighted TSE-sequences with low Echotime, high image matrix and thin sections without fat saturation, T1-weighted IR-sequences yielded an intermediate contrast-ratio with optimal depiction of the defect depth.
Conclusion: Appropriate MR imaging parameter selection is crucial for optimized visualization of the matrix and has the potential to provide information about matrix integrity and success of cartilage repair.
217. Use of a Novel Percutaneous Biopsy Localization Device: Initial Experience
Morrison W.B.1; Deely D.M.1; Koulouris G.1*; Zoga A.C.1; Roberts C.C.2; 1. Radiology, Thomas Jefferson University Hospital, Philadelphia, PA; 2. Radiology, Mayo Clinic, Scottsdale, AZ.
Address correspondence to G. Koulouris (drgeorgek{at}mbox.com.au)
Objective: The SeeStar (Radi Medical Devices, Uppsala, Sweden) is a new device that is taped to the skin and has a lockable needle guide can be moved nearly 180 degrees in all directions. It could potentially facilitate percutaneous musculoskeletal biopsy in certain settings. We sought to evaluate the device for application in patients by first using an in vitro model.
Materials and Methods: Two sections of a beef carcass were used to test the device. A 22 gauge seven inch needle was placed into the meat at different locations to act as a target. Localization with a 16g soft tissue gun (Meditech, Boston Scientific, Watertown, MA) was performed using CT guidance (Lightspeed Helical, GE Medical Systems, Milwaukee, WI) with a standard goniometer method and then using the SeeStar. CT slice thickness was altered to optimize localization. Technique and advantages for particular biopsy situations were recorded.
Results: The needle guide of the SeeStar device creates a dark
linear artifact that allows for prediction of final needle position; this
makes it advantageous for rapid biopsy of small lesions. However, a beveled
needle can alter the course despite accurate localizer planning. Additionally,
initially the artifact was found to extend only a short distance from the
skin. Placement of a 1
inch 18 gauge needle into the needle guide
increased the length and visibility of the artifact. Changing slice thickness
from 5mm to 3mm and 1mm further increased artifact visibility. The movable
locking needle guide allows for localization before breaking the skin, making
the device potentially useful for small, deep lesions or in situations where
biopsy must be performed rapidly. The needle guide outside the patient
stabilizes the biopsy gun, helping prevent "drooping" of the gun
and change of course during scanning, especially for superficial lesions and
for lesions that must be accessed using a horizontal orientation.
Conclusion: The SeeStar device is potentially useful for facilitating percutaneous musculoskeletal biopsy, particularly for superficial lesions, for deep/ small lesions, and for lesions that must be accessed via atypical routes. Techniques that increase CT artifact improve usefulness of the device by increasing visibility of a dark, linear artifact that extends from the device's needle guide.
* Will present paper
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