Mini N. Pathria

MR appearance of idiopathic synovial osteochondromatosis.

Objective A retrospective review of the MR examinations in 21 patients with idiopathic synovial osteochondromatosis (ISO) was performed to determine its MRI characteristics. Materials and Methods Twenty-one patients diagnosed with ISO had undergone MRI prior to surgery. The MR images were retrospectively evaluated for configuration and extent of lesion as well as for signal characteristics. Results Three distinct MR patterns were seen in ISO: A—lobulated homogeneous intraarticular signal isointense to slightly hyperintense to muscle on T1-weighted images and hyperintense on T2-weighted images (n = 3); B—pattern A plus foci of signal void on all pulse sequences (n = 17); and C—features of pattern A and B plus foci of peripheral low signal surrounding central fat-like signal (n = 2). The foci of signal void in pattern B and C corresponded to areas of calcification and the foci of peripheral low signal surrounding central fat-like signal in pattern C corresponded to areas of ossification. Conclusion The MR appearance of ISO appears sufficiently unique to allow its differentiation from other causes of intraarticular pathology.

Evaluation of the postoperative meniscus of the knee: a study comparing conventional arthrography, conventional MR imaging, MR arthrography with iodinated contrast material, and MR arthrography with gadolinium-based contrast material.

Abstract Objective. To compare four imaging methods in the evaluation of the postoperative meniscus: conventional arthrography, conventional MR imaging, MR arthrography with iodinated contrast material, and MR arthrography with gadolinium-based contrast material. Design and patients. Thirty-three patients referred for knee MR examinations with a history of meniscal surgery were studied prospectively. At the first patient visit, conventional MR examination was followed by an MR arthrogram with gadolinium-based contrast material. At the second visit, a conventional arthrogram with iodinated contrast material was followed immediately by an MR examination. Imaging examinations were interpreted by a masked reader, and then compared with the results of repeat arthroscopic surgery in 12 patients. Results. The correct evaluation of the status of postoperative menisci was allowed in 12 of 13 patients (92%) by MR arthrography using gadolinium-based contrast agent, 10 of 13 patients (77%) by conventional MR examination, 9 of 12 patients (75%) by MR arthrography, and 7 of 12 patients (58%) by conventional arthrography. Conclusion. Intra-articular fluid is advantageous in the evaluation of patients with a suspected meniscal retear. MR arthrography with gadolinium-based contrast material is the most accurate imaging method for the diagnosis of meniscal retears.

Combined Magnetic Fields Accelerate and Increase Spine Fusion : A Double-Blind, Randomized, Placebo Controlled Study

STUDY DESIGN The clinical study conducted was a prospective, randomized, double-blind, placebo-controlled trial. OBJECTIVES The purpose of this study was to evaluate the effect of combined magnetic fields on the healing of primary noninstrumented posterolateral lumbar spine fusion. SUMMARY OF BACKGROUND DATA Combined magnetic fields, a new type of biophysical stimulus, have been shown to act by stimulating endogenous production of growth factors that regulate the healing process. This is the first placebo-controlled study to assess the effect of an electromagnetic stimulus on primary noninstrumented posterolateral lumbar spine fusion surgery as well as the first evaluation of combined magnetic fields as an adjunctive stimulus to lumbar spine fusion. METHODS This multicenter investigational study was conducted at 10 clinical sites under an Investigational Device Exemption from the United States Food and Drug Administration. Eligible patients had one-level or two-level fusions (between L3 and S1) without instrumentation, either with autograft alone or in combination with allograft. The combined magnetic field device used a single posterior coil, centered over the fusion site, with one 30-minute treatment per day for 9 months. Randomization was stratified by site and number of levels fused. Evaluation was performed 3, 6, and 9 months after surgery and 3 months after the end of treatment. The primary endpoint was assessment of fusion at 9 months, based on radiographic evaluation by a blinded panel consisting of the treating physician, a musculoskeletal radiologist, and a spine surgeon. RESULTS Of 243 enrolled patients, 201 were available for evaluation. Among all patients with active devices, 64% healed at 9 months compared with 43% of patients with placebo devices: a significant difference (P = 0.003 by Fishers exact test). Stratification by gender showed fusion in 67% of women with active devices, compared with 35% of those with placebo devices (P = 0.001 by Fishers exact test). By contrast, there was not a statistically significant effect of the active device in this male study population. In the overall population of 201 patients, repeated measures analyses of fusion outcomes (by generalized estimating equations) showed a main effect of treatment, favoring the active treatment (P = 0.030). In a model with main effect and a time by treatment interaction, the latter was significant (P = 0.024), indicating acceleration of healing. Performed in the full sample of 243 patients, results of the intent-to-treat analysis were qualitatively the same as in the evaluable sample of 201 patients. DISCUSSION This investigational study demonstrates that combined magnetic field treatment of 30 min/d increases the probability of successful spine fusion, and statistical analysis using the generalized estimating equations model suggests an acceleration of the healing process. This is the first randomized clinical trial of noninstrumented primary posterolateral lumbar spine fusion, with evaluation by a blinded, unbiased panel. This is the first double-blind study performed to date assessing noninstrumented fusion outcome with extremely critical radiographic criteria. The lower overall fusion rates in this study are attributed to the high-risk patient group with an average age of 57 years, the use of noninstrumented technique with posterolateral fusion only, and the reliance on extremely critical radiographic and clinical criteria and blinded panel for fusion assessment without surgical confirmation. CONCLUSIONS In conclusion, the adjunctive use of the combined magnetic field device was statistically beneficial in the overall patient population, as has been shown in previous studies of adjunctive bone growth stimulation for spine fusion. For the first time, stratification of fusion success data by gender demonstrated that the female study population responded positively to the adjunctive combined magnetic field treatment, with no statistically significant effect observed in the male study population. Adjunctive use of the combined magnetic field device significantly increased the 9-month success of radiographic spinal fusion and showed an acceleration of the healing process.

Assessment of pedicle screw placement utilizing conventional radiography and computed tomography: A proposed systematic approach to improve accuracy of interpretation

Study Design. This was a human cadaver study to determine the accuracy of conventional radiography and computed radiography in the evaluation of pedicle screw placement and to identify methodology for more precise reading of these examinations. Objectives. To determine the accuracy of conventional radiography and computed tomography in the evaluation of pedicle screw placement within lumbar vertebral pedicles and to develop methods to improve imaging interpretation. Summary of Background Data. Conventional radiography and computed tomography have been used in research and clinical settings to evaluate pedicle screw placement. This study evaluates the interpretative accuracy of readers blinded to the true position of screw placement using both imaging examinations. Furthermore, methodology was developed to improve accuracy of interpretation of these examinations. Methods. Three cadaver lumbar spines were instrumented bilaterally with pedicle screws from L1 to L5. Thirty pedicles had 6.0 mm AO pedicle screws inserted using standard surgical technique. Seven directions of deliberate misplacement as well as correct placement of screws were performed at random levels for a total of eight possible screw positions. Conventional radiographs and computed tomography scans were obtained. A senior musculoskeletal radiologist and senior spine surgeon interpreted the images while blinded to screw placement. Examiners initially assessed the screws as in or out, followed by assessment of the eight possible types of screw position. Consensus interpretation was obtained regarding the placement of individual screws. The spines were then dissected to visualize the screws and their position related to the pedicle. After determining the true position of the screws, a systematic method was designed and applied to the interpretation of the imaging methods to identify screw positions. Results. Using conventional radiographs, 63% of the screw placements were correctly identified as in or out of the pedicle. Computed tomography improved accuracy to 87%. Identifying the true directional component of screw position led to a decrease in accuracy (conventional radiographs 37% and computed tomography 47%). Using asystematic method to analyze imaging studies enabled detection of screw positions. Conclusion. Evaluation of pedicle screw placement is difficult even in experienced hands. A systematic approach to image interpretation should allow for an accurate assessment of pedicle screw placement.

Grading liposarcomas with PET using [18F]FDG

Five patients with liposarcomas of the thigh were studied using positron emission tomography (PET) with [18F]2-deoxy-2-fluoroglucose (FDG). There were three low-grade tumors (all National Cancer Institute Grade 1 myxoid liposarcomas) and two high-grade tumors (both pleomorphic liposarcomas, Grades 2 and 3). The low-grade liposarcomas were easily identified with an average dose uptake ratio (DUR) of 1.38 +/- 0.045 (mean +/- SD). The high-grade lesions were more avid for FDG with a mean DUR of 2.45 +/- 0.24. There was a significant difference (p = 0.004) in the DUR for the two groups and the histological grade of malignancy was highly correlated with the DUR for FDG (Rho = 0.89). These findings suggest that FDG-PET may be useful for distinguishing between low-grade and high-grade liposarcomas.

Denervation hypertrophy of muscle: MR features.

Objective Denervation hypertrophy is an entity well recognized in the neurology literature, but with little mention in the radiology literature. Denervation hypertrophy occurs when a muscle paradoxically enlarges rather than atrophies in response to loss of innervation. The purpose of this report is to describe the MR appearance of true hypertrophy and pseudohypertrophy of muscle following denervation. Materials and Methods The clinical data and MRI findings in three patients with muscle enlargement due to denervation hypertrophy are reviewed retrospectively. Two women and one man aged 19–80 years were included. Denervation resulted from spinal stenosis in one patient, a herniated thoracic disc in another, and spina bifida with a tethered cord in the third. Results True hypertrophy of a single muscle was seen in one patient and pseudohypertrophy of two muscles was present in one patient. One patient had one muscle with true hypertrophy and one muscle with pseudohypertrophy. Electromyographic examination was performed and was consistent with denervation in two patients. Biopsy confirmation of denervation was obtained in two patients. All five abnormal muscles exhibited increased volume, well defined margins, and normal contour. In true hypertrophy the enlarged muscle was isointense with normal muscle on all MRI sequences. In pseudohypertrophy the MRI appearance was consistent with an excessive amount of fat interspersed throughout normal muscle. Conclusion Magnetic resonance in these cases established muscle hypertrophy rather than neoplasm as the cause of a palpable mass. If muscle hypertrophy or pseudohypertrophy is seen on an MR examination of an enlarged extremity, the possibility of an underlying neurologic process should be considered.

Pelvic instability after bone graft harvesting from posterior iliac crest: report of nine patients

Abstract  Objective. To report the imaging findings in nine patients who developed pelvic instability after bone graft harvest from the posterior aspect of the iliac crest. Design and patients. A retrospective study was performed of the imaging studies of nine patients who developed pelvic pain after autologous bone graft was harvested from the posterior aspect of the ilium for spinal arthrodesis. Plain films, bone scans, and CT and MR examinations of the pelvis were reviewed. Pertinent aspects of the clinical history of these patients were noted, including age, gender and clinical symptoms. Results. The age of the patients ranged from 52 to 77 years (average 69 years) and all were women. The bone graft had been derived from the posterior aspect of the iliac crest about the sacroiliac joint. All patients subsequently developed subluxation of the pubic symphysis. Eight patients had additional insufficiency fractures of the iliac crest adjacent to the bone graft donor site, and five patients also revealed subluxation of the sacroiliac joint. Two had insufficiency fractures of the sacrum and one had an additional fracture of the pubic ramus. Conclusions. Pelvic instability is a potential complication of bone graft harvesting from the posterior aspect of the iliac crest. The pelvic instability is manifested by insufficiency fractures of the ilium and subluxation of the sacroiliac joints and pubic symphysis.

Terminal Bifurcation of the Biceps Brachii Muscle and Tendon: Anatomic Considerations and Clinical Implications

OBJECTIVE The objective of our study was to describe the anatomic variation of a bifurcated distal biceps tendon with MRI, histology, and dissection in cadavers and to report the MR appearance of superimposed lesions in a patient population with this anatomic variant. MATERIALS AND METHODS Visual and histologic examinations of the distal biceps brachii tendon in eight sectioned fresh-frozen elbow specimens were performed. Dissection of 17 elbow specimens was performed to describe the distal biceps brachii tendon. In addition, all elbow MRI reports over a 3-year period (n = 411) were retrospectively reviewed to determine the presence of bifurcation of the distal biceps brachii tendon. RESULTS The distal biceps brachii tendon appeared bifurcated in 25% of the sectioned specimens, and these findings were confirmed histologically. The distal biceps brachii tendon was completely separable into two components-that is, a short head and long head- throughout their proximal to distal extent in 41.2% of the dissected specimens. The distal biceps brachii tendon appeared bifurcated in 11.8% of 68 clinical cases that showed distal biceps brachii tendon abnormalities or injuries. The following patterns of injury were noted: complete rupture of both tendons (n = 1), complete rupture of the short head and normal insertion of the long head (n = 2), complete rupture of the short head and partial tear of the long head (n = 2), partial tear of both tendons (n = 2), and complete rupture of the short head and tendinosis in the long head (n = 1). CONCLUSION A bifurcated distal biceps brachii tendon is an anatomic variant that arises from persistent division between the short head and long head of the distal biceps brachii tendon and can be characterized with MRI. Knowledge of a bifurcated distal biceps brachii tendon is important to characterize injury to the components and to avoid pitfalls in imaging diagnosis.

Posterolateral and Posteromedial Corner Injuries of the Knee

Posterolateral (PLC) and posteromedial (PMC) corners of the knee represent complex anatomic regions because of intricate soft tissue and osseous relationships in small areas. Concise knowledge of these relationships is necessary before approaching their evaluation at imaging. Magnetic resonance imaging offers an accurate imaging diagnostic tool to establish normal anatomy and diagnose and characterize soft tissue and osseous injury. It is important to carefully evaluate the PLC and PMC structures on magnetic resonance imaging before planned surgical intervention to avoid potential complications resulting from occult injury.

Patterns of central acetabular osteophytosis in osteoarthritis of the hip.

RATIONALE AND OBJECTIVES The frequency and morphology of central acetabular osteophyte formation were evaluated in patients with osteoarthritis. METHODS One hundred preserved acetabular specimens were evaluated for the occurrence of central osteophytes (excrescences present in the articulation of the hip joint), their relationship to marginal and femoral osteophytes of the hip, and their radiographic appearance. RESULTS In both specimen and patient analysis, the authors found that central excrescences occur commonly and appear to be related temporally to osteophytes of the femur and the margin of the acetabulum. CONCLUSIONS The authors demonstrated a close relationship between the degree of marginal and femoral osteophytes with those found centrally, indicating a temporal relationship. The new radiographic signs discussed are: 1) a fine linear density associated with early osteoarthritis; 2) larger, more irregular densities associated with a more advanced stage of osteoarthritis; and 3) obliteration of the acetabular fossa by excrescences as found in severe osteoarthritis.