Faculty Bibliography

Bone strength is affected not only by bone mineral density (BMD) and bone microarchitecture but also its microenvironment. Recent studies have focused on the role of marrow adipose tissue (MAT) in the pathogenesis of bone loss. Osteoblasts and adipocytes arise from a common mesenchymal stem cell within bone marrow and many osteoporotic states, including aging, medication use, immobility, over - and undernutrition are associated with increased marrow adiposity. Advancements in imaging technology allow the non-invasive quantification of MAT. This article will review magnetic resonance imaging (MRI)- and computed tomography (CT)-based imaging technologies to assess the amount and composition of MAT. The techniques that will be discussed are anatomic T1-weighted MRI, water-fat imaging, proton MR spectroscopy, single energy CT and dual energy CT. Clinical applications of MRI and CT techniques to determine the role of MAT in patients with obesity, anorexia nervosa, and type 2 diabetes will be reviewed.

Research into bone marrow adiposity (BMA) has expanded greatly since the late 1990s, leading to development of new methods for the study of bone marrow adipocytes. Simultaneously, research fields interested in BMA have diversified substantially. This increasing interest is revealing fundamental new knowledge of BMA; however, it has also led to a highly variable nomenclature that makes it difficult to interpret and compare results from different studies. A consensus on BMA nomenclature has therefore become indispensable. This article addresses this critical need for standardised terminology and consistent reporting of parameters related to BMA research. The International Bone Marrow Adiposity Society (BMAS) was formed in 2017 to consolidate the growing scientific community interested in BMA. To address the BMA nomenclature challenge, BMAS members from diverse fields established a working group (WG). Based on their broad expertise, the WG first reviewed the existing, unsystematic nomenclature and identified terms, and concepts requiring further discussion. They thereby identified and defined 8 broad concepts and methods central to BMA research. Notably, these had been described using 519 unique combinations of term, abbreviation and unit, many of which were overlapping or redundant. On this foundation a second consensus was reached, with each term classified as "to use" or "not to use." As a result, the WG reached a consensus to craft recommendations for 26 terms related to concepts and methods in BMA research. This was approved by the Scientific Board and Executive Board of BMAS and is the basis for the present recommendations for a formal BMA nomenclature. As an example, several terms or abbreviations have been used to represent "bone marrow adipocytes," including BMAds, BM-As, and BMAs. The WG decided that BMA should refer to "bone marrow adiposity"; that BM-A is too similar to BMA; and noted that "Ad" has previously been recommended to refer to adipocytes. Thus, it was recommended to use BMAds to represent bone marrow adipocytes. In conclusion, the standard nomenclature proposed in this article should be followed for all communications of results related to BMA. This will allow for better interactions both inside and outside of this emerging scientific community.

OBJECTIVE:To evaluate progression of osteoarthritis and femoral head articular surface collapse in hip steroid/anesthetic injection patients (HIPs). MATERIALS AND METHODS/METHODS:This study was IRB-approved and HIPAA-compliant. Two musculoskeletal radiologists performed retrospective, blinded reviews of radiography for 70 HIPs (40 mg triamcinolone/4 mL 0.5% preservative-free ropivacaine) with a 3- to 10-month follow-up and two control groups: demographic-matched patients with similar hip radiograph follow-up duration but no injection; and glenohumeral joint injection patients. Discordant evaluations were adjudicated by a third, senior reader. Groups were compared using Fisher's exact and unpaired t tests. RESULTS:There were 70 HIPs (mean age 67 ± 17 (range 19-92) years; 44 women, 26 men), who were followed for a mean of 6 ± 2 (3-12) months. Thirty-one (31 out of 70, 44%) of HIPs had progression of osteoarthritis after injection, versus 17 out of 70 (24%) of hip controls (HCs) and 13 out of 44 (30%) of glenohumeral injection patients (GIPs). This difference between HIPs and HCs was statistically significant (p = 0.02) but not that between HIPs and GIPs (0.17). Twelve (12 out of 70, 17%) HIPs had new collapse, compared with 1 out of 70 (1%) of HCs and 1 out of 44 (2%) of GIPs. This difference was statistically significant (HCs: p = 0.002; GIPs: p = 0.02). CONCLUSION/CONCLUSIONS:Hip steroid/anesthetic injection patients are more likely to demonstrate osteoarthritis progression and femoral head collapse than HC and GIPs in the injected joint 3-12 months after steroid and anesthetic injection. Further evaluation of hip injectates and the injection population is warranted.

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms composed of perivascular epithelioid cells that are immunoreactive for both melanocytic and myogenic markers. Recently, a fibroma-like PEComa associated with tuberous sclerosis complex (TSC) has been identified. We describe the first intra-articular case of a fibroma-like PEComa in a 44-year-old man who presented with a hypointense intra-articular knee mass, which was mistaken for tenosynovial giant cell tumor, diffuse type. This case report demonstrates that fibroma-like PEComa should be included in the extended differential diagnosis of intra-articular soft tissue masses. In addition, given their strong association with TSC mutations, a diagnosis of fibroma-like PEComa should trigger an evaluation for TSC.

Mentorship plays a critical role in the success of academic radiologists. Faculty members with mentors have better career opportunities, publish more papers, receive more research grants, and have greater overall career satisfaction. However, with the increasing focus on clinical productivity, pressure on turn-around times, and the difficult funding climate, effective mentoring in academic radiology can be challenging. The high prevalence of "burnout" among radiologists makes mentorship even more important. This article reviews benefits and challenges of mentorship in academic radiology, discusses how to institute a faculty mentoring program, examines different types of mentoring, and reviews challenges related to diversity and inclusion.

OBJECTIVE:In anorexia nervosa, a psychiatric disease characterized by self-induced starvation and a model of chronic undernutrition, levels of subcutaneous (SAT) and visceral (VAT) adipose tissue are low, whereas marrow adipose tissue (MAT) levels are elevated compared to normal-weight women. The reason for this paradoxical elevation of an adipose tissue depot in starvation is not known. We sought to understand changes in MAT in response to subacute changes in weight and to compare these changes with those of other fat depots and body composition parameters. DESIGN AND METHODS/METHODS:We conducted a 12-month longitudinal study including 46 premenopausal women (n = 26 with anorexia nervosa and n = 20 normal-weight controls) with a mean (s.e.m.) age of 28.2 ± 0.8 years. We measured MAT, SAT, VAT and bone mineral density (BMD) at baseline and after 12 months. RESULTS:At baseline, SAT (P < 0.0001), VAT (P < 0.02) and BMD of the spine and hip (P ≤ 0.0002) were significantly lower and vertebral and metaphyseal MAT (P ≤ 0.001) significantly higher in anorexia nervosa compared to controls. Weight gain over 12 months was associated with increases not only in SAT and VAT, but also epiphyseal MAT (P < 0.03). Changes in epiphyseal MAT were positively associated with changes in BMD (P < 0.03). CONCLUSIONS:In contrast to the steady state, in which MAT levels are higher in anorexia nervosa and MAT and BMD are inversely associated, short-term weight gain is associated with increases in both MAT and BMD. These longitudinal data demonstrate the dynamic nature of this fat depot and provide further evidence of its possible role in mineral metabolism.

BACKGROUND:Despite their higher areal bone mineral density (aBMD), adolescents with obesity (OB) have an increase in fracture risk, particularly of the extremities, compared with normal-weight controls. Whereas bone parameters that increase fracture risk are well characterized in anorexia nervosa (AN), the other end of nutritional spectrum, these data are lacking in adolescents with obesity. OBJECTIVE:Our objective was to compare bone parameters in adolescent girls across the nutritional spectrum, to determine whether suboptimal bone adaptation to increased body weight may explain the increased fracture risk in OB. METHODS:We assessed bone endpoints in 153 adolescent girls 14-21 years old: 50 OB, 48 controls and 55 AN. We used (i) DXA to assess aBMD at the lumbar spine, proximal femur and whole body, and body composition, (ii) high resolution peripheral quantitative CT (HRpQCT) to assess bone geometry, microarchitecture and volumetric BMD (vBMD), and (iii) finite element analysis to assess failure load (a strength estimate) at the distal radius and tibia. All aBMD, microarchitecture and FEA analyses were controlled for age and race. RESULTS:Groups did not differ for age or height. Areal BMD Z-scores at all sites were highest in OB, intermediate in controls and lowest in AN (p < 0.0001). At the radius, cortical area and thickness were higher in OB compared to AN and control groups (p = 0.001) while trabecular area did not differ across groups. Compared to controls, OB had higher cortical porosity (p = 0.003), higher trabecular thickness (p = 0.024), and higher total, cortical and trabecular vBMD and rod BV/TV (p < 0.04). Plate BV/TV did not differ in OB vs. controls, but was higher than in AN (p = 0.001). At the tibia, total, cortical, and trabecular area and cortical thickness were higher in OB vs. controls and AN (p < 0.005). OB also had higher cortical porosity (p < 0.007) and lower trabecular thickness (p < 0.02) than the other two groups. Trabecular number, total and trabecular vBMD, and rod BV/TV were higher in OB vs. controls and AN (p < 0.02), while cortical vBMD and plate BV/TV did not differ in OB vs. the other two groups. Finally, failure load (a strength estimate) was higher in OB at the radius and tibia compared to controls and AN (p < 0.004 for all). However, after adjusting for body weight, failure load was lower in OB vs. controls at both sites (p < 0.05), and lower than in AN at the distal tibia. CONCLUSION:Not all bone parameters demonstrate appropriate adaptation to higher body weight. Cortical porosity and plate BV/TV at the radius and tibia, and cortical vBMD and trabecular thickness at the tibia are particularly at risk. These effects may contribute to the higher risk for fracture reported in OB vs. controls.

OBJECTIVE:To demonstrate fluoroscopy dose reduction through both simulated injections on a phantom and patient injections. MATERIALS AND METHODS/METHODS:Our study was IRB-approved and HIPAA-compliant. Simulation on a phantom was used to estimate effective dose, entrance dose, and organ doses for hip joint injections without and with dose minimization technique (DMT). Additionally, 1,094 joint, bursae, and tendon sheath injections performed by three operators in the same fluoroscopy suite were evaluated both before and after application of DMT. Fluoroscopy time (FT), dose, and dose area product (DAP) of injections were compared using unpaired t-tests with P > 0.05 considered statistically significant. RESULTS:) for all three operators decreased with DMT and remained statistically significant when stratified by the two most common injections, glenohumeral and hip joint injections (P < 0.05). CONCLUSIONS:FT, effective dose, entrance dose, and DAP can be reduced with the use of simple easy-to-learn techniques, which will benefit both the patient and the radiologist.

BACKGROUND:Altered bone microarchitecture and higher marrow adipose tissue (MAT) may reduce bone strength. High resolution pQCT (HRpQCT) allows assessment of volumetric BMD (vBMD), and size and microarchitecture parameters of bone, while 1H-magnetic resonance spectroscopy (1H-MRS) allows MAT evaluation. We have reported impaired microarchitecture at the non-weight bearing radius in adolescents with anorexia nervosa (AN) and that these changes may precede aBMD deficits. Data are lacking regarding effects of AN on microarchitecture and strength at the weight-bearing tibia in adolescents and young adults, and the impact of changes in microarchitecture and MAT on strength estimates. OBJECTIVE:To compare strength estimates at the distal tibia in adolescents/young adults with AN and controls in relation to vBMD, bone size and microarchitecture, and spine MAT. DESIGN AND METHODS/METHODS:This was a cross-sectional study of 47 adolescents/young adults with AN and 55 controls 14-24years old that assessed aBMD and body composition using DXA, and distal tibia vBMD, size, microarchitecture and strength estimates using HRpQCT, extended cortical analysis, individual trabecular segmentation, and finite element analysis. Lumbar spine MAT (1H-MRS) was assessed in a subset of 19 AN and 22 controls. RESULTS:Areal BMD Z-scores were lower in AN than controls. At the tibia, AN had greater cortical porosity, lower total and cortical vBMD, cortical area and thickness, trabecular number, and strength estimates than controls. Within AN, strength estimates were positively associated with lean mass, aBMD, vBMD, bone size and microarchitectural parameters. MAT was higher in AN, and associated inversely with strength estimates. CONCLUSIONS:Adolescents/young adults with AN have impaired microarchitecture at the weight-bearing tibia and higher spine MAT, associated with reduced bone strength.