Gabrielle Bergman

Gadolinium-DTPA-enhanced magnetic resonance imaging of musculoskeletal infectious processes

The purpose of this study was to assess whether gadolinium-enhanced magnetic resonance imaging (MRI) provides diagnostic information beyond that given by nonenhanced imaging in the evaluation of musculoskeletal infectious processes and whether it can be used for differentiating infectious from noninfectious inflammatory lesions. Magnetic resonance images performed with and without intravenous gadolinium-DTPA in 34 cases in which musculoskeletal infection had been clinically suspected were reviewed. Infectious lesionsincluding osteomyelitis, pyarthrosis, abscess, and cellulitis-were confirmed in a total of 22 cases: in 15 by biopsy or drainage and in 7 by clinical course. Our results show that gadolinium-DTPA-enhanced MRI is a highly sensitive technique in diagnosing musculoskeletal infectious lesions. It is especially useful in distinguishing abscesses from surrounding cellulitis/myositis. Lack of contrast enhancement rules out infection with a high degree of certainty. However, contrast enhancement cannot be used to reliably distinguish infectious from noninfectious inflammatory conditions.The purpose of this study was to assess whether gadolinium-enhanced magnetic resonance imaging (MRI) provides diagnostic information beyond that given by nonenhanced imaging in the evaluation of musculoskeletal infectious processes and whether it can be used for differentiating infectious from noninfectious inflammatory lesions. Magnetic resonance images performed with and without intravenous gadolinium-DTPA in 34 cases in which musculoskeletal infection had been clinically suspected were reviewed. Infectious lesionsincluding osteomyelitis, pyarthrosis, abscess, and cellulitis-were confirmed in a total of 22 cases: in 15 by biopsy or drainage and in 7 by clinical course. Our results show that gadolinium-DTPA-enhanced MRI is a highly sensitive technique in diagnosing musculoskeletal infectious lesions. It is especially useful in distinguishing abscesses from surrounding cellulitis/myositis. Lack of contrast enhancement rules out infection with a high degree of certainty. However, contrast enhancement cannot be used to reliably distinguish infectious from noninfectious inflammatory conditions.

Mr Imaging of articular cartilage using driven equilibrium

The high incidence of osteoarthritis and the recent advent of several new surgical and non‐surgical treatment approaches have motivated the development of quantitative techniques to assess cartilage loss. Although magnetic resonance (MR) imaging is the most accurate non‐invasive diagnostic modality for evaluating articular cartilage, improvements in spatial resolution, signal‐to‐noise ratio (SNR), and contrast‐to‐noise ratio (CNR) would be valuable. Cartilage presents an imaging challenge due to its short T2 relaxation time and its low water content compared with surrounding materials. Current methods sacrifice cartilage signal brightness for contrast between cartilage and surrounding tissue such as bone, bone marrow, and joint fluid. A new technique for imaging articular cartilage uses driven equilibrium Fourier transform (DEFT), a method of enhancing signal strength without waiting for full T1 recovery. Compared with other methods, DEFT imaging provides a good combination of bright cartilage and high contrast between cartilage and surrounding tissue. Both theoretical predictions and images show that DEFT is a valuable method for imaging articular cartilage when compared with spoiled gradient‐recalled acquisition in the steady state (SPGR) or fast spin echo (FSE). The cartilage SNR for DEFT is as high as that of either FSE or SPGR, while the cartilage‐synovial fluid CNR of DEFT is as much as four times greater than that of FSE or SPGR. Implemented as a three‐dimensional sequence, DEFT can achieve coverage comparable to that of other sequences in a similar scan time. Magn Reson Med 42:695–703, 1999.

Segmental mobility of the lumbar spine during a posterior to anterior mobilization: assessment using dynamic MRI

OBJECTIVES To quantify segmental mobility of the lumbar spine during a posterior to anterior spinal mobilization procedure. DESIGN Descriptive study using dynamic magnetic resonance imaging. BACKGROUND The posterior to anterior spinal mobilization procedure is frequently used in the assessment and management of spinal dysfunction. How this procedure influences segmental spinal motion however, is not known. METHODS Eleven asymptomatic subjects were positioned prone within a vertically open double donut design magnetic resonance imaging system. An anteriorly directed force was applied manually at each lumbar spinous process while magnetic resonance images were obtained continuously in the sagittal plane. The intervertebral angle was used to quantify segmental motion. RESULTS The direction of motion at the tested segment was always extension, with values ranging from 1.2 (SD 2.2) at L2 to 3.0 (SD 2.3) degrees at L5. When the force was applied at L3, L4 and L5, the non-tested (adjacent) segments also were observed to move into extension. However, when the posterior to anterior force was applied at L1 and L2 the three caudal segments moved into flexion. CONCLUSIONS Posterior to anterior spinal mobilization consistently caused extension at the tested segment, while the motion of the collective lumbar spine was either an increase or decrease in lordosis depending on the segment at which the force was applied. RELEVANCE Passive movement techniques are commonly used to identify the symptomatic lumbar segment(s) and can be used as a treatment aimed at increasing mobility and/or decreasing pain. Knowledge of how this procedure influences segmental motion of healthy spines is important in understanding how altered mobility is related to symptoms.

Do Capacitively Coupled Electric Fields Accelerate Tibial Stress Fracture Healing.

Background Tibial stress fractures increasingly affect athletes and military recruits, with few known effective management options. Electrical stimulation enhances regular fracture healing, but the effect on stress fractures has not been definitively tested. Hypothesis Capacitively coupled electric field stimulation will accelerate tibial stress fracture healing. Study Design Randomized controlled trial; Level of evidence, 1. Methods Twenty men and 24 women with acute posteromedial tibial stress fractures were referred from local clinicians. Subjects were randomly assigned active or placebo capacitively coupled electric field stimulation to be applied for 15 hours per day until healed, given supplemental calcium, and instructed to rest from provocative training. Healing was confirmed when hopping to 10 cm for 30 seconds could be achieved without pain. Results No difference in time to healing was detected between treatment and placebo groups. Women in the treatment group healed more slowly than did the men (P = .05). Superior treatment compliance was associated with reduced time to healing (P = .003). Rest noncompliance was associated with increased time to healing (P = .05). Conclusion Whole-group analysis did not detect an effect of capacitively coupled electric field stimulation on tibial stress fracture healing; however, greater device use and less weightbearing loading enhanced the effectiveness of the active device. More severe stress fractures healed more quickly with capacitively coupled electric field stimulation. Clinical Relevance Although the use of capacitively coupled electric field stimulation for tibial stress fracture healing may not be efficacious for all, it may be indicated for the more severely injured or elite athlete/recruit whose incentive to return to activity may motivate superior compliance.

Magnetization transfer contrast MRI of musculoskeletal neoplasms

Magnetic resonance imaging (MRI) examinations were performed in 15 patients with musculoskeletal neoplasms to assess the value of magnetization transfer contrast in tumor characterization. Multiplanar gradient-recalled echo sequences (TR 500-600/TE 15-20/flip angle 20–30°) were performed first without and then with magnetization transfer contrast generated by a zero degree binomial pulse (MPGR and MTMPGR). Standard T1-weighted spin echo images (SE; TR 300-400/TE 12-20) and either T2-weighted SE (TR 2000-2900/TE 70-80) or T2-weighted fast spin echo (FSE; TR 4000-5000/TE 100-119 effective) images were also obtained. Signal intensities on MTMPGR scans were compared to those on MPGR scans for both tumors and normal tissues. Signal intensity ratios (SIR) and contrast-to-noise ratios (CNR) were also compared for all sequences. MTMPGR images provided better contrast between pathologic tissues and muscle than did standard MPGR images, increasing both conspicuity of lesions and definition of tumor/muscle interfaces. Benign and malignant tumors, with the exception of lipoma, underwent similar degrees of magnetization transfer and could not be distinguished by this technique.

Femoral diaphyseal stress fractures: results of a systematic bone scan and magnetic resonance imaging evaluation in 25 runners

Abstract Objective : The purpose of this study was to evaluate femoral diaphyseal stress injuries in runners and to document the results of a systematic grading system based on magnetic resonance imaging (MRI) and radionuclide bone study. Design : A retrospective review of medical records and radiologic findings on patients seen between 1992–2002. Grading was preformed of triple phase bone scan and MRI results. Setting : Stanford University Medical Center, Sports Medicine Clinic. Patients : Twenty-five track and field varsity team members and recreational runners subsequently diagnosed with 31 femoral diaphyseal stress injuries. Outcome measures : Sixteen MRIs and 19 bone scans were evaluated with previously established grading systems. Results : Injury location in 31 femoral diaphyseal stress fractures included the proximal femur in 18 (58.1%), the midfemur in 11 (35.5%), and the distal femur in two legs (6.5%). MRI grading revealed grade I in two of 16 (12.5%), grade II in seven of 16 (43.8%), and grade III in seven of 16 (43.8%) runners. Radionuclide bone study grading revealed grade I in four of 19 (21.1%), grade II in nine of 19 (47.4%), and grade III in six of 19 (31.6%) runners. There was close correlation between grade of MRI and radionuclide bone study in the 12 athletes who had both exams, with 91.7% coincidence. Conclusion : These data of 25 femoral diaphyseal stress fractures show that women were more frequently affected than men and nearly half of these injuries occurred in first-year collegiate runners. The location was mainly in the proximal femur, on the compressive side of bone. If routine radiographs are negative, a radionuclide bone study or MRI with fat-suppression technique can be used to detect and grade bony changes in the femoral diaphyses and to help plan an appropriate rehabilitation program.

Original researchFemoral diaphyseal stress fractures: results of a systematic bone scan and magnetic resonance imaging evaluation in 25 runners

Abstract Objective : The purpose of this study was to evaluate femoral diaphyseal stress injuries in runners and to document the results of a systematic grading system based on magnetic resonance imaging (MRI) and radionuclide bone study. Design : A retrospective review of medical records and radiologic findings on patients seen between 1992–2002. Grading was preformed of triple phase bone scan and MRI results. Setting : Stanford University Medical Center, Sports Medicine Clinic. Patients : Twenty-five track and field varsity team members and recreational runners subsequently diagnosed with 31 femoral diaphyseal stress injuries. Outcome measures : Sixteen MRIs and 19 bone scans were evaluated with previously established grading systems. Results : Injury location in 31 femoral diaphyseal stress fractures included the proximal femur in 18 (58.1%), the midfemur in 11 (35.5%), and the distal femur in two legs (6.5%). MRI grading revealed grade I in two of 16 (12.5%), grade II in seven of 16 (43.8%), and grade III in seven of 16 (43.8%) runners. Radionuclide bone study grading revealed grade I in four of 19 (21.1%), grade II in nine of 19 (47.4%), and grade III in six of 19 (31.6%) runners. There was close correlation between grade of MRI and radionuclide bone study in the 12 athletes who had both exams, with 91.7% coincidence. Conclusion : These data of 25 femoral diaphyseal stress fractures show that women were more frequently affected than men and nearly half of these injuries occurred in first-year collegiate runners. The location was mainly in the proximal femur, on the compressive side of bone. If routine radiographs are negative, a radionuclide bone study or MRI with fat-suppression technique can be used to detect and grade bony changes in the femoral diaphyses and to help plan an appropriate rehabilitation program.

Predisposing Characteristics for Tibial Stress Fracture

Tibial stress fractures (TSF) increasingly affect athletes and military recruits, and are challenging to manage. There is a need to identify the characteristics most associated with the incidence of TSF in order for preventative strategies to be developed, and/or screening to be implemented where appropriate. PURPOSE To identify physical and behavioural characteristics related to incidence of tibial stress fracture in men and women. METHODS Twenty-seven patients (13 M, 14 F) with TSF and 27 age-, sex-, height-, weight-, and activity-matched subjects with no history of stress fracture were recruited. Physical (height, weight, menstrual history, bone parameters, lower limb alignment anomaly) and behavioural (diet, meds, oral contraceptives, training) characteristics were recorded from all subjects via anthropometry, questionnaire, dual-energy x-ray absorptiometry and quantitative ultrasound. Between group differences were examined via one-way ANOVA. RESULTS Stress fracture subjects exhibited shorter femoral necks (FN) with smaller FN area and thinner cortices, but greater lumbar spine (LS) bone mineral density (BMD), bone mineral apparent density (BMAD), stiffness (E) and strength index (IBS). Foot type also differed between groups with 70% of controls having normal feet versus 40% of fractured subjects. There were no other between group differences in any other anthropometric or behavioural variable. Split file analyses revealed subtle sex-specific characteristics. Only foot type differed between groups for men; the control group exhibiting fewer anomalies. All the aforementioned differences in bone parameters were apparent between female groups, with greater FN bone mineral content (BMC) and lower LS BMC in controls also becoming significant. CONCLUSION Foot anomalies appear to be the characteristic most associated with TSF for men; whereas women suffering TSF appear to have smaller bones of the lower extremity, but stronger lumbar spines than those who have never fractured. Supported by US Army MRMC, DAMD17-98-1-8519, and BIOLECTRON, Inc. now EBI, Parsippany, NJ.

Do Capacitively Coupled Electric Fields Accelerate Tibial Stress Fracture Healing?: 878

Abstract : An average of three months rest is generally recommended for resolution of tibial stress fractures. Such an extended absence from athletic or military training reduces the ability to perform optimally and the likelihood of successful return to activity upon recovery. Electric field stimulation has been shown to accelerate bone healing. While there is reason to believe that this effect will extend to the healing of stress fractures, no rigorous investigations of this application have been performed. We are collecting data in order to compare recovery times from tibial stress fracture in male and female subjects treated with either active or placebo-control electric field stimulation. There is an associated need to establish a cost effective, reliable method of diagnostic imaging for tibial stress fractures. Four forms of diagnostic imaging (radiographs, bone scan, MRI and CT) are performed on each subject. The films will be evaluated according to the ability of each to identify tibial stress fractures and predict time to healing. Establishment of a stress fracture severity grading system for each imaging technique will facilitate predictions of recovery times with and without electric field stimulation according to degree of injury. We have collected data from seven subjects in Year 1, however, due to the nature of the study design, we are unable to report findings until the conclusion of the investigation when the devices will be unblinded. Further, to maximize intra-evaluator reliability, reading and grading of all films should occur simultaneously, thus no imaging evaluation will occur until data collection is complete.

Bone Stress Injuries

This unit outlines basic MRI protocols for evaluating the most common bone stress injuries including those of the tibia, femoral neck, femoral shaft, metatarsal, and navicular bone. The protocols concentrate on the lower extremity, as the majority of stress injures occur in this region. These protocols were developed using a 1.5 T system (Signa, General Electric Medical Systems). However, the sequences described could be adapted to low‐ or mid‐field scanners using STIR (short tau inversion recovery) sequences to acquire the T2‐weighted images. This technique would thus require longer scan times and lower resolution matrices.