Chronic Nonspinal Osteomyelitis in Adults: Consensus Recommendations on Percutaneous Bone Biopsies from the Society of Academic Bone Radiologists.

The diagnosis and management of chronic nonspinal osteomyelitis can be challenging, and guidelines regarding the appropriateness of performing percutaneous image-guided biopsies to acquire bone samples for microbiological analysis remain limited. An expert panel convened by the Society of Academic Bone Radiologists developed and endorsed consensus statements on the various indications for percutaneous image-guided biopsies to standardize care and eliminate inconsistencies across institutions. The issued statements pertain to several commonly encountered clinical presentations of chronic osteomyelitis and were supported by a literature review. For most patients, MRI can help guide management and effectively rule out osteomyelitis when performed soon after presentation. Additionally, in the appropriate clinical setting, open wounds such as sinus tracts and ulcers, as well as joint fluid aspirates, can be used for microbiological culture to determine the causative microorganism. If MRI findings are positive, surgery is not needed, and alternative sites for microbiological culture are not available, then percutaneous image-guided biopsies can be performed. The expert panel recommends that antibiotics be avoided or discontinued for an optimal period of 2 weeks prior to a biopsy whenever possible. Patients with extensive necrotic decubitus ulcers or other surgical emergencies should not undergo percutaneous image-guided biopsies but rather should be admitted for surgical debridement and intraoperative cultures. Multidisciplinary discussion and approach are crucial to ensure optimal diagnosis and care of patients diagnosed with chronic osteomyelitis.

Gender and age differences in the associations between cortical thickness and hand osteoarthritis severity: data from the Osteoarthritis Initiative.

OBJECTIVE: To evaluate gender differences in the association between metacarpal cortical thickness (Tcort)-a surrogate for bone density-and severity of radiographic hand osteoarthritis (HOA) in a longitudinal observational study. METHOD: Hand radiographs of 3575 participants (2039 F/1536 M) from the Osteoarthritis Initiative were assessed at baseline and 48 months. A reader used a semi-automated software tool to calculate Tcort, a measurement of the cortical thickness, for metacarpals 2-4. Average Tcort at baseline and change in Tcort from baseline to 48 months was determined and stratified by gender and age for 7 5-year age groups. Spearman's rank correlation coefficients were calculated for the association of baseline Tcort and 2 measures of baseline HOA severity: the sum of Kellgren-Lawrence (KL) grade and total number of joints with radiographic HOA. Longitudinally, logistic regression was used to assess the relationship of Tcort loss to new finger joint radiographic HOA, increase in KL grades, and incident hand pain. RESULTS: Male Tcort was higher than females. Significant correlations between Tcort and radiographic severity were noted for women but not men, with stronger associations among women >60 years (rho = -0.25; 95% confidence interval (CI) = -0.31 to -0.19). Statistically significant associations were seen between Tcort change and radiographic osteoarthritis change among women but not men, with substantial gender differences for Tcort change, particularly ages 50 to 70 years (p < 0.01; e.g., Tcort change ages 55 to <60: males = -0.182 (0.118), females = -0.219 (0.124)). CONCLUSION: We found significant HOA-related gender differences in Tcort, suggesting the involvement of female bone loss during and after menopause.

Associations of inflammatory and metabolic biomarkers with incident erosive hand osteoarthritis in the osteoarthritis initiative cohort.

OBJECTIVE: Erosive hand osteoarthritis (eHOA) is a subtype of hand osteoarthritis (OA) that develops in finger joints with pre-existing OA and is differentiated by clinical characteristics (hand pain/disability, inflammation, and erosions) that suggest inflammatory or metabolic processes. METHOD: This was a longitudinal nested case-cohort design among Osteoarthritis Initiative participants who had hand radiographs at baseline and 48-months, and biospecimens collected at baseline. We classified incident radiographic eHOA in individuals with ≥1 joint with Kellgren-Lawrence ≥2 and a central erosion present at 48-months but not at baseline. We used a random representative sample (n = 1282) for comparison. We measured serum biomarkers of inflammation, insulin resistance and dysglycemia, and adipokines using immunoassays and enzymatic colorimetric procedures, blinded to case status. RESULTS: Eighty-six participants developed incident radiographic eHOA. In the multivariate analyses adjusted for age, gender, race, smoking, and body mass index, and after adjustment for multiple analyses, incident radiographic eHOA was associated with elevated levels of interleukin-7 (risk ratio (RR) per SD = 1.30 [95% confidence interval (CI) 1.09, 1.55] p trend 0.01). CONCLUSION: This exploratory study suggests an association of elevated interleukin-7, an inflammatory cytokine, with incident eHOA, while other cytokines or biomarkers of metabolic inflammation were not associated. Interleukin-7 may mediate inflammation and tissue damage in susceptible osteoarthritic finger joints and participate in erosive progression.

Quantitative bone marrow lesion, meniscus, and synovitis measurement: current status.

Imaging plays a pivotal role in osteoarthritis research, particularly in epidemiological and clinical trials of knee osteoarthritis (KOA), with the ultimate goal being the development of an effective drug treatment for future prevention or cessation of disease. Imaging assessment methods can be semi-quantitative, quantitative, or a combination, with quantitative methods usually relying on software to assist. The software generally attempts image segmentation (outlining of relevant structures). New techniques using artificial intelligence (AI) or deep learning (DL) are currently a frequent topic of research. This review article provides an overview of the literature to date, focusing primarily on the current status of quantitative software-based assessment techniques of KOA using magnetic resonance (MR) imaging. We will concentrate on the imaging evaluation of three specific structural imaging biomarkers: bone marrow lesions (BMLs), meniscus, and synovitis consisting of effusion synovitis (ES) and Hoffa's synovitis (HS). A brief clinical and imaging background review of osteoarthritis evaluation, particularly relating to these three structural markers, is provided as well as a general summary of the software methods. A summary of the literature with respect to each KOA assessment method will be presented overall as well as with respect to each specific biomarker individually. Novel techniques, as well as future goals and directions using quantitative imaging assessment, will be discussed.

Whole-body Computed Tomography Versus Dual Energy X­ray Absorptiometry for Assessing Heterotopic Ossification in Fibrodysplasia Ossificans Progressiva.

Fibrodysplasia ossificans progressiva (FOP) is an ultra-rare genetic disorder that leads to heterotopic ossification (HO), resulting in progressive restriction of physical function. In this study, low-dose, whole-body computed tomography (WBCT) and dual energy X-ray absorptiometry (DXA) were evaluated to determine the preferred method for assessing total body burden of HO in patients with FOP. This was a non-interventional, two-part natural history study in patients with FOP (NCT02322255; date of registration: December 2014). In Part A (described here), WBCT and DXA scans were individually assessed for HO presence and severity across 15 anatomical regions. All images were independently reviewed by an expert imaging panel. Ten adult patients were enrolled across four sites. The sensitivity to HO presence and severity varied considerably between the two imaging modalities, with WBCT demonstrating HO in more body regions than DXA (76/138 [55%] versus 47/113 [42%]) evaluable regions). Inability to evaluate HO presence, due to overlapping body regions (positional ambiguity), occurred less frequently by WBCT than by DXA (mean number of non-evaluable regions per scan 1.2 [standard deviation: 1.5] versus 2.4 [1.4]). Based on the increased sensitivity and decreased positional ambiguity of low-dose WBCT versus DXA in measuring HO in patients with FOP, low-dose WBCT was chosen as the preferred imaging for measuring HO. Therefore, low-dose WBCT was carried forward to Part B of the natural history study, which evaluated disease progression over 36 months in a larger population of patients with FOP.

Do non-weight-bearing knee radiographs for chronic knee pain result in increased follow-up imaging?

OBJECTIVE: While weight-bearing radiographs are considered the optimal method for evaluation of joint spaces in osteoarthritis, non-weight-bearing radiographs are often performed. The purpose of this study is to evaluate the rate of follow-up radiographs in patients receiving non-weight-bearing radiographs for chronic knee pain in the outpatient setting, compared with patients receiving weight-bearing radiographs. MATERIALS AND METHODS: Consecutive patients who received non-weight-bearing knee radiographs for chronic knee pain between January 1, 2018, and June 15, 2019, were included. Exclusion criteria included trauma, concern for infection or tumor, and post-surgical radiographs. An age- and sex-matched control group of 100 patients who received weight-bearing knee radiographs was compiled. The proportion of follow-up radiographs within 1 year was compared between the study and control groups with chi-squared tests. RESULTS: Four hundred non-weight-bearing knee radiographic examinations were included. There were 74/400 (18.5%) follow-up radiographs within 12 months. All follow-up radiographs were weight-bearing. In the control group, 4/100 (4%) had follow-up weight-bearing radiographs within 1 year (p < 0.001). CONCLUSION: Outpatients who underwent non-weight-bearing knee radiographs for chronic pain had a higher frequency of repeat imaging than those who initially underwent weight-bearing knee radiographs. These results suggest that non-weight-bearing knee radiographs are of lower clinical utility compared with weight-bearing radiographs.

Use of Advanced Imaging for Radiographically Occult Hip Fracture in Elderly Patients: A Systematic Review and Meta-Analysis.

Background The overall rate of hip fractures not identified on radiographs but that require surgery (ie, surgical hip fractures) remains unclear in elderly patients who are suspected to have such fractures based on clinical findings. Moreover, the importance of advanced imaging in these patients has not been comprehensively assessed. Purpose To estimate the frequency of radiographically occult hip fracture in elderly patients, to define the higher-risk subpopulation, and to determine the diagnostic performance of CT and bone scanning in the detection of occult fractures by using MRI as the reference standard. Materials and Methods A literature search was performed to identify English-language observational studies published from inception to September 27, 2018. Studies were included if patients were clinically suspected to have hip fracture but there was no radiographic evidence of surgical hip fracture (including absence of any definite fracture or only presence of isolated greater trochanter [GT] fracture). The rate of surgical hip fracture was reported in each study in which MRI was used as the reference standard. The pooled rate of occult fracture, diagnostic performance of CT and bone scanning, and strength of evidence (SOE) were assessed. Results Thirty-five studies were identified (2992 patients; mean age, 76.8 years ± 6.0 [standard deviation]; 66% female). The frequency of radiographically occult surgical hip fracture was 39% (1110 of 2835 patients; 95% confidence interval [CI]: 35%, 43%) in studies of patients with no definite radiographic fracture and 92% (134 of 157 patients; 95% CI: 83%, 98%) in studies of patients with radiographic evidence of isolated GT fracture (moderate SOE). The frequency of occult fracture was higher in patients aged at least 80 years (44%, 529 of 1184), those with an equivocal radiographic report (58%, 71 of 126), and those with a history of trauma (41%, 977 of 2370) (moderate SOE). CT and bone scanning yielded comparable diagnostic performance in the detection of radiographically occult hip fracture (P = .67), with a sensitivity of 79% and 87%, respectively (low SOE). Conclusion Elderly patients with acute hip pain and negative or equivocal findings at initial radiography have a high frequency of occult hip fractures. Therefore, the performance of advanced imaging (preferably MRI) may be clinically appropriate in all such patients. © RSNA, 2020 Online supplemental material is available for this article.

Bone Marrow Edema at Dual-Energy CT: A Game Changer in the Emergency Department.

Dual-energy CT is increasingly being used in the emergency department to help diagnose acute conditions. Its applications include demonstrating bone marrow edema (BME) seen in the setting of occult fractures and other acute conditions. Dual-energy CT acquires data with two different x-ray energy spectra and is able to help differentiate materials on the basis of their differential energy-dependent x-ray absorption behaviors. Virtual noncalcium (VNCa) techniques can be used to suppress the high attenuation of trabecular bone, thus enabling visualization of subtle changes in the underlying attenuation of the bone marrow. Visualization of BME can be used to identify occult or mildly displaced fractures, pathologic fractures, metastases, and some less commonly visualized conditions such as ligamentous injuries or inflammatory arthritis. The authors' major focus is use of dual-energy CT as a diagnostic modality in the setting of trauma and to depict subtle or occult fractures. The authors also provide some scenarios in which dual-energy CT is used to help diagnose other acute conditions. The causes and pathophysiology of BME are reviewed. Dual-energy CT image acquisition and VNCa postprocessing techniques are also discussed, along with their applications in emergency settings. The authors present potential pitfalls and limitations of these techniques and their possible solutions.©RSNA, 2020.

Temporomandibular joint imaging: current clinical applications, biochemical comparison with the intervertebral disc and knee meniscus, and opportunities for advancement.

Temporomandibular disorders encompass multiple pathologies of the temporomandibular joint that manifest as middle/inner ear symptoms, headache, and/or localized TMJ symptoms. There is an important although somewhat limited role of imaging in the diagnostic evaluation of temporomandibular disorders. In this manuscript, we provide a comprehensive review of TMJ anatomy, outline potentially important features of TMJ disc ultrastructure and biochemistry in comparison with the intervertebral disc and knee meniscus, and provide imaging examples of the TMJ abnormalities currently evaluable with MRI and CT. In addition, we provide an overview of emerging and investigational TMJ imaging techniques in order to encourage further imaging research based on the biomechanical alterations of the TMJ disc.

Thinking beyond pannus: a review of retro-odontoid pseudotumor due to rheumatoid and non-rheumatoid etiologies.

Retro-odontoid pseudotumor, or mass-like retro-odontoid soft tissue thickening, is an uncommon but important imaging finding that may be associated with rheumatoid arthritis, crystal deposition diseases, as well as non-inflammatory conditions such as cervical degenerative changes and mechanical alterations. Retro-odontoid pseudotumor is commonly associated with atlantoaxial microinstability or subluxation. MRI and CT have an important role in the detection and diagnosis of retro-odontoid pseudotumor. However, due to a wide range of imaging characteristics and ambiguous etiology, it is a frequently misunderstood entity. The purpose of this article is to review relevant anatomy of the craniocervical junction; describe various imaging appearances, pathophysiology and histology in both rheumatoid and non-rheumatoid etiologies; and discuss differential diagnosis of retro-odontoid pseudotumor in order to help guide clinical management.

The associations between radiographic hand osteoarthritis definitions and hand pain: data from the osteoarthritis initiative.

The goal of our study was to evaluate the associations between various definitions of radiographic hand osteoarthritis (OA) and self-reported hand pain. We conducted a cross-sectional study with 3604 participants from the Osteoarthritis Initiative (OAI). Posteroanterior radiographs of the dominant hand were read using a modified Kellgren-Lawrence (KL) scale. For our primary analysis, hand OA at person level was defined as two or more finger joints with KL grade 2 or higher. In addition, for the purpose of exploratory analyses, we explored more conservative definitions of hand OA as well as different sum scores and digit- and row-based scores. The majority of definitions of radiographic hand OA were statistically significantly associated with self-reported hand pain. In our main analysis, persons with two or more finger joints with KL grade > 2 were approximately two times more likely to self-report hand pain than persons without radiographic hand OA. Increasing KL grades and increasing number of joints affected lead to stronger associations. Almost all definitions of hand OA were related to pain. Individuals with more severely affected joints or with higher number of affected joints are more likely to report hand pain than their peers. Specifically, individuals with hand joints with KL 3 or 4 have the greatest likelihood of hand pain.

Osteomyelitis of the lower extremity: pathophysiology, imaging, and classification, with an emphasis on diabetic foot infection.

Osteomyelitis is inflammation of the bone caused by an infectious organism, and is a difficult clinical problem. The pathophysiology, imaging, and classification of osteomyelitis are challenging, varying with the age of the patient (child versus adult), the chronicity of the infection (acute versus chronic), and the route of spread (hematogenous versus contiguous focus), as well as the immune and vascular status of the patient and affected region. The two most common classification schemes are those of Lew and Waldvogel, and Cierny and Mader. Brodie's abscess is seen in subacute osteomyelitis, while sequestrum, involucrum, and cloaca are inter-related entities of chronic osteomyelitis. Imaging workup of suspected osteomyelitis should begin with radiographs, although MRI is the most accurate imaging test. Three patterns of T1 signal change have been described in the setting of suspected osteomyelitis including confluent intramedullary, hazy reticular, and subcortical. The confluent intramedullary pattern is most associated with osteomyelitis, while hazy reticular is rarely associated with hematogenous osteomyelitis, and subcortical is not associated with osteomyelitis. It can be challenging to differentiate neuropathic arthropathy from osteomyelitis. Osteomyelitis tends to involve a single bone subjacent to an ulcer or sinus tract. In contrast, neuropathic arthropathy tends to involve multiple bones of the midfoot. Subchondral cystic change, thin rim enhancement of a joint effusion, and the presence of intra-articular bodies are more indicative of a neuropathic joint without infection. Biopsy can play an important role in diagnosis and treatment of osteomyelitis.

Gender Differences in Academic Rank of Radiologists in U.S. Medical Schools.

Purpose To determine whether there were gender differences in full professorship after accounting for factors known to influence academic advancement. Materials and Methods Institutional review board approval was obtained for this HIPAA-compliant study, with waiver of informed consent. In this cross-sectional study, the authors used a comprehensive 2014 physician database (5089 academic radiologists, inclusive of all U.S. academic radiologists in 2014; 11.3% of all U.S. radiologists) containing information on physician age, years since residency, National Institutes of Health funding, scientific publications (first or last author and total), clinical trial investigation, and clinical volume measured according to 2013 Medicare reimbursement. Primary outcome of gender differences in full professorship was estimated by using a multilevel logistic regression model adjusting for these factors. Results Among 5089 academic radiologists, 3638 (71.5%) were men. The average age for male and female radiologists was 52 and 49 years, respectively. Overall, 239 women (16.5%) and 948 (26.1%) men were full professors (P < .001). Women had fewer total and first or last author publications than men (total, 12.2 vs 17.6; first or last, 6.8 vs 10.7; P < .001 for both comparisons). Women were less likely than men to have National Institutes of Health funding (2.0% vs 3.6%; P = .004) and generated less annual Medicare revenue ($63 346 vs $75 854; P = .001). After multivariate adjustment, rates of full professorship among female and male radiologists were not significantly different (absolute adjusted difference for female vs male radiologists, -1.5%; 95% confidence interval: -3.8%, 0.9%). Conclusion Among radiologists with U.S. medical school faculty appointments in 2014, men and women were similarly likely to be full professor after several factors known to influence promotion were taken into account. However, unadjusted differences in promotion and research productivity were present, which suggests that female radiologists may lack equal research opportunities. © RSNA, 2016.

Inhibition of Human Metapneumovirus Binding to Heparan Sulfate Blocks Infection in Human Lung Cells and Airway Tissues.

UNLABELLED: Human metapneumovirus (HMPV), a recently discovered paramyxovirus, infects nearly 100% of the world population and causes severe respiratory disease in infants, the elderly, and immunocompromised patients. We previously showed that HMPV binds heparan sulfate proteoglycans (HSPGs) and that HMPV binding requires only the viral fusion (F) protein. To characterize the features of this interaction critical for HMPV binding and the role of this interaction in infection in relevant models, we utilized sulfated polysaccharides, heparan sulfate mimetics, and occluding compounds. Iota-carrageenan demonstrated potent anti-HMPV activity by inhibiting binding to lung cells mediated by the F protein. Furthermore, analysis of a minilibrary of variably sulfated derivatives of Escherichia coli K5 polysaccharide mimicking the HS structure revealed that the highly O-sulfated K5 polysaccharides inhibited HMPV infection, identifying a potential feature of HS critical for HMPV binding. The peptide dendrimer SB105-A10, which binds HS, reduced binding and infection in an F-dependent manner, suggesting that occlusion of HS at the target cell surface is sufficient to prevent infection. HMPV infection was also inhibited by these compounds during apical infection of polarized airway tissues, suggesting that these interactions take place during HMPV infection in a physiologically relevant model. These results reveal key features of the interaction between HMPV and HS, supporting the hypothesis that apical HS in the airway serves as a binding factor during infection, and HS modulating compounds may serve as a platform for potential antiviral development. IMPORTANCE: Human metapneumovirus (HMPV) is a paramyxovirus that causes respiratory disease worldwide. It has been previously shown that HMPV requires binding to heparan sulfate on the surfaces of target cells for attachment and infection. In this study, we characterize the key features of this binding interaction using heparan sulfate mimetics, identify an important sulfate modification, and demonstrate that these interactions occur at the apical surface of polarized airway tissues. These findings provide insights into the initial binding step of HMPV infection that has potential for antiviral development.

Burnout: Prevalence and Associated Factors Among Radiology Residents in New England With Comparison Against United States Resident Physicians in Other Specialties.

OBJECTIVE: The objective of our study was to establish burnout prevalence, associated demographic and program-related factors, and degree of burnout in New England radiology residents relative to residents in other specialties. MATERIALS AND METHODS: A 31-item survey, including nine demographic and program-related questions and the 22-item Maslach Burnout Inventory-Health Services Survey, was sent to all resident members of the New England Roentgen Ray Society (20 programs, 472 residents). Emotional exhaustion (EE), depersonalization (DP), and personal accomplishment (PA) scores were calculated and stratified using published normative data. Multiple linear regression analysis was performed to identify burnout predictors. Chi-square testing with Bonferroni correction was performed to confirm predictors associated with high burnout. The EE, DP, and PA scores were compared with the results of residents from other specialties. RESULTS: There were 94 responses. High EE, high DP, and low PA scores were reported by 37%, 48%, and 50% of respondents, respectively. EE, DP, and PA scores and rates were low relative to those reported across specialties. Increasing residency year correlated with high EE (p = 0.002) and high DP (p < 0.001). No other factor significantly correlated with burnout. CONCLUSION: A high degree of burnout, increasing over the postgraduate years, was present in more than one-third of responding radiology residents but was present in a smaller percentage relative to residents across other specialties. Radiology residents score relatively poorly in PA and therefore addressing PA may be central to improving burnout symptoms overall.

Sex Differences in Radiologist Salary in U.S. Public Medical Schools.

OBJECTIVE: The purpose of this study was to evaluate salary differences between male and female academic radiologists at U.S. medical schools. MATERIALS AND METHODS: Laws in several U.S. states mandate public release of government records, including salary information of state employees. From online salary data published by 12 states, we extracted the salaries of all academic radiologists at 24 public medical schools during 2011-2013 (n = 573 radiologists). In this institutional review board-approved cross-sectional study, we linked these data to a physician database with information on physician sex, age, faculty rank, years since residency, clinical trial involvement, National Institutes of Health (NIH) funding, scientific publications, and clinical volume measured by 2013 Medicare payments. Sex difference in salary, the primary outcome, was estimated using a multilevel logistic regression adjusting for these factors. RESULTS: Among 573 academic radiologists, 171 (29.8%) were women. Female radiologists were younger (48.5 vs 51.6 years, p = 0.001) and more likely to be assistant professors (50.9% [87/171] vs 40.8% [164/402], p = 0.026). Salaries between men and women were similar in unadjusted analyses ($290,660 vs $289,797; absolute difference, $863; 95% CI, -$18,363 to $20,090), and remained so after adjusting for age, faculty rank, years since residency, clinical trial involvement, publications, total Medicare payments, NIH funding, and graduation from a highly ranked medical school. CONCLUSION: Among academic radiologists employed at 24 U.S. public medical schools, male and female radiologists had similar annual salaries both before and after adjusting for several variables known to influence salary among academic physicians.

Stress fractures of the foot and ankle, part 2: site-specific etiology, imaging, and treatment, and differential diagnosis.

Stress fractures of the foot and ankle are a commonly encountered problem among athletes and individuals participating in a wide range of activities. This illustrated review, the second of two parts, discusses site-specific etiological factors, imaging appearances, treatment options, and differential considerations of stress fractures of the foot and ankle. The imaging and clinical management of stress fractures of the foot and ankle are highly dependent on the specific location of the fracture, mechanical forces acting upon the injured site, vascular supply of the injured bone, and the proportion of trabecular to cortical bone at the site of injury. The most common stress fractures of the foot and ankle are low risk and include the posteromedial tibia, the calcaneus, and the second and third metatarsals. The distal fibula is a less common location, and stress fractures of the cuboid and cuneiforms are very rare, but are also considered low risk. In contrast, high-risk stress fractures are more prone to delayed union or nonunion and include the anterior tibial cortex, medial malleolus, navicular, base of the second metatarsal, proximal fifth metatarsal, hallux sesamoids, and the talus. Of these high-risk types, stress fractures of the anterior tibial cortex, the navicular, and the proximal tibial cortex may be predisposed to poor healing because of the watershed blood supply in these locations. The radiographic differential diagnosis of stress fracture includes osteoid osteoma, malignancy, and chronic osteomyelitis.

Stress fractures of the foot and ankle, part 1: biomechanics of bone and principles of imaging and treatment.

A stress fracture is a focal failure of bone induced by the summation of repetitive forces, which overwhelms the normal bone remodeling cycle. This review, the first of two parts, discusses the general principles of stress fractures of the foot and ankle. This includes bone structure, biomechanics of stress applied to bone, bone remodeling, risk factors for stress fracture, and general principles of imaging and treatment of stress fractures. Cortical bone and trabecular bone have a contrasting macrostructure, which leads to differing resistances to externally applied forces. The variable and often confusing imaging appearance of stress fractures of the foot and ankle can largely be attributed to the different imaging appearance of bony remodeling of trabecular and cortical bone. Risk factors for stress fracture can be divided into intrinsic and extrinsic factors. Stress fractures subject to compressive forces are considered low-risk and are treated with activity modification and correction of any modifiable risk factors. Stress fractures subject to tensile forces and/or located in regions of decreased vascularity are considered high risk, with additional treatment options including restricted weight-bearing or surgery.

Acute non-contact anterior cruciate ligament tears are associated with relatively increased vastus medialis to semimembranosus cross-sectional area ratio: a case-control retrospective MR study.

OBJECTIVE: Hamstring muscle deficiency is increasingly recognized as a risk factor for anterior cruciate ligament (ACL) tears. The purpose of this study is to evaluate the vastus medialis to semimembranosus cross-sectional area (VM:SM CSA) ratio on magnetic resonance imaging (MRI) in patients with ACL tears compared to controls. MATERIALS AND METHODS: One hundred knee MRIs of acute ACL tear patients and 100 age-, sex-, and side-matched controls were included. Mechanism of injury, contact versus non-contact, was determined for each ACL tear subject. The VM:SM CSA was measured on individual axial slices with a novel method using image-processing software. One reader measured all 200 knees and the second reader measured 50 knees at random to assess inter-reader variability. The intraclass correlation coefficient (ICC) was calculated to evaluate for correlation between readers. T-tests were performed to evaluate for differences in VM:SM CSA ratios between the ACL tear group and control group. RESULTS: The ICC for agreement between the two readers was 0.991 (95% confidence interval 0.984-0.995). Acute ACL tear patients have an increased VM:SM CSA ratio compared to controls (1.44 vs. 1.28; p = 0.005). Non-contact acute ACL tear patients have an increased VM:SM CSA ratio compared to controls (1.48 vs. 1.20; p = 0.003), whereas contact acute ACL tear patients do not (1.23 vs. 1.26; p = 0.762). CONCLUSION: Acute non-contact ACL tears are associated with increased VM:SM CSA ratios, which may imply a relative deficiency in hamstring strength. This study also demonstrates a novel method of measuring the relative CSA of muscles on MRI.

Routine clinical knee MR reports: comparison of diagnostic performance at 1.5 T and 3.0 T for assessment of the articular cartilage.

OBJECTIVE: Accurate assessment of knee articular cartilage is clinically important. Although 3.0 Tesla (T) MRI is reported to offer improved diagnostic performance, literature regarding the clinical impact of MRI field strength is lacking. The purpose of this study is to compare the diagnostic performance of clinical MRI reports for assessment of cartilage at 1.5 and 3.0 T in comparison to arthroscopy. MATERIALS AND METHODS: This IRB-approved retrospective study consisted of 300 consecutive knees in 297 patients who had routine clinical MRI and arthroscopy. Descriptions of cartilage from MRI reports of 165 knees at 1.5 T and 135 at 3.0 T were compared with arthroscopy. The sensitivity, specificity, percent of articular surfaces graded concordantly, and percent of articular surfaces graded within one grade of the arthroscopic grading were calculated for each articular surface at 1.5 and 3.0 T. Agreement between MRI and arthroscopy was calculated with the weighted-kappa statistic. Significance testing was performed utilizing the z-test after bootstrapping to obtain the standard error. RESULTS AND CONCLUSIONS: The sensitivity, specificity, percent of articular surfaces graded concordantly, and percent of articular surfaces graded within one grade were 61.4%, 82.7%, 62.2%, and 77.5% at 1.5 T and 61.8%, 80.6%, 59.5%, and 75.6% at 3.0 T, respectively. The weighted kappa statistic was 0.56 at 1.5 T and 0.55 at 3.0 T. There was no statistically significant difference in any of these parameters between 1.5 and 3.0 T. Factors potentially contributing to the lack of diagnostic advantage of 3.0 T MRI are discussed.