Faculty Bibliography

Visceral adiposity is a strong determinant of growth hormone (GH) secretion, and states of GH deficiency are associated with increased visceral adiposity and decreased lean body mass. The purpose of our study was to determine the sensitivity and specificity of different methods of assessing body composition [anthropometry, dual-energy X-ray absorptiometry (DXA), and computed tomography (CT)] to predict GH deficiency in premenopausal women and threshold values for each technique to predict GH deficiency, using receiver operator characteristic (ROC) curve analysis. We studied a group of 45 healthy lean, overweight, and obese premenopausal women who underwent anthropometric measurements (body mass index, waist and hip circumferences, skin fold thickness), DXA, CT, and a GH-releasing hormone-arginine stimulation test. ROC curve analysis was used to determine cutoff values for each method to identify GH deficiency. Visceral adiposity measured by CT showed the highest sensitivity and specificity for identifying subjects with GH deficiency with a cutoff of >9,962 mm(2) [area under the curve (AUC), 0.95; sensitivity, 100%; specificity, 77.8%; P = 0.0001]. Largest waist circumference showed high sensitivity and specificity with a cutoff of >101.7 cm (AUC, 0.89; sensitivity, 88.9%; specificity, 75%; P = 0.0001). When the ROC curves of visceral fat measured by CT and largest waist circumference were compared, the difference between the two methods was not statistically significant (P = 0.36). Our study showed that the largest waist circumference predicts the presence of GH deficiency in healthy premenopausal women with high sensitivity and specificity and nearly as well as CT measurement of visceral adiposity. It can be used to identify women in whom GH deficiency is likely and therefore in whom formal GH stimulation testing might be indicated.

PURPOSE/OBJECTIVE:To examine trabecular microarchitecture with high-resolution flat-panel volume computed tomography (CT) and bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA) in adolescent girls with anorexia nervosa (AN) and to compare these results with those in normal-weight control subjects. MATERIALS AND METHODS/METHODS:The study was approved by the institutional review board and complied with HIPAA guidelines. Informed consent was obtained. Twenty adolescent girls, 10 with mild AN (mean age, 15.9 years; range, 13-18 years) and 10 age- and sex-matched normal-weight control subjects (mean age, 15.9 years; range, 12-18 years) underwent flat-panel volume CT of distal radius to determine apparent trabecular bone volume fraction (BV/TV), apparent trabecular number (TbN), apparent trabecular thickness (TbTh), and apparent trabecular separation (TbSp). All subjects underwent DXA of spine, hip, and whole body to determine BMD and body composition. The means and standard deviations (SDs) of structure parameters were calculated for AN and control groups. Groups were compared (Student t test). Linear regression analysis was performed. RESULTS:AN subjects compared with control subjects, respectively, showed significantly lower mean values for BV/TV (0.37% +/- 0.05 [SD] vs 0.46% +/- 0.03, P = .0002) and TbTh (0.31 mm +/- 0.03 vs 0.39 mm +/- 0.03, P < .0001) and higher mean values for TbSp (0.54 mm +/- 0.13 vs 0.44 mm +/- 0.04, P = .02). TbN was lower in AN subjects than in control subjects, but the difference was not significant (1.17 mm(-3) +/- 0.15 vs 1.22 mm(-3) +/- 0.07, P = .43). There was no significant difference in BMD between AN and control subjects. BMD parameters showed positive correlation with BV/TV and TbTh in the control group (r = 0.55-0.84, P = .05-.01) but not in AN patients. CONCLUSION/CONCLUSIONS:Flat-panel volume CT is effective in evaluation of trabecular structure in adolescent girls with AN and demonstrates that bone structure is abnormal in these patients compared with that in normal-weight control subjects despite normal BMD. SUPPLEMENTAL MATERIAL/BACKGROUND:http://radiology.rsnajnls.org/cgi/content/full/249/3/938/DC1.

Flat-panel volume computed tomography (fpVCT) is a recent development in imaging. We discuss some of the musculoskeletal applications of a high-resolution flat-panel CT scanner. FpVCT has four main advantages over conventional multidetector computed tomography (MDCT): high-resolution imaging; volumetric coverage; dynamic imaging; omni-scanning. The overall effective dose of fpVCT is comparable to that of MDCT scanning. Although current fpVCT technology has higher spatial resolution, its contrast resolution is slightly lower than that of MDCT (5-10HU vs. 1-3HU respectively). We discuss the efficacy and potential utility of fpVCT in various applications related to musculoskeletal radiology and review some novel applications for pediatric bones, soft tissues, tumor perfusion, and imaging of tissue-engineered bone growth. We further discuss high-resolution CT and omni-scanning (combines fluoroscopic and tomographic imaging).

The bony anatomy of the hip leads to a limited array of impingement syndromes, more frequently resulting from abnormal contact between the femoral neck and acetabulum. We report an unusual case of osseous impingement between the lesser trochanter and ischium, with involvement of the intervening quadratus femoris muscle. While the prevalence and etiology of this finding is unclear, it may represent a cause for hip pain.

Although body composition, insulin sensitivity, and lipids are markedly altered in overweight adolescents, hormonal associations with these parameters have not been well characterized. Growth hormone (GH) deficiency and hypercortisolemia predispose to abdominal adiposity and insulin resistance, and GH secretion is decreased in obese adults. We hypothesized that low-peak GH on the GH-releasing hormone (GHRH)-arginine stimulation test and high cortisol in overweight adolescents would be associated with higher regional fat, insulin resistance, and lipids. We examined the following parameters in 15 overweight and 15 bone age-matched control 12- to 18-yr-old girls: 1) body composition using dual-energy X-ray absorptiometry and MR [visceral and subcutaneous adipose tissue at L(4)-L(5) and soleus intramyocellular lipid ((1)H-MR spectroscopy)], 2) peak GH on the GHRH-arginine stimulation test, 3) mean overnight GH and cortisol, 4) 24-h urinary free cortisol (UFC), 5) fasting lipids, and 6) an oral glucose tolerance test. Stepwise regression was the major tool employed to determine relationships between measured parameters. Log peak GH on the GHRH-arginine test was lower (P = 0.03) and log UFC was higher (P = 0.02) in overweight girls. Log mean cortisol (overnight sampling) was associated positively with subcutaneous adipose tissue and, with body mass index standard deviation score, accounted for 92% of its variability, whereas log peak GH and body mass index standard deviation score accounted for 88% of visceral adipose tissue variability and log peak GH for 34% of the intramyocellular lipid variability. Log mean cortisol was independently associated with log homeostasis model assessment of insulin resistance, LDL, and HDL and explained 49-59% of the variability. Our data indicate that lower peak GH and higher UFC in overweight girls are associated with visceral adiposity, insulin resistance, and lipids.

This review describes a range of shoulder injuries experienced by baseball pitchers. It is estimated that more than 57% of pitchers suffer some form of shoulder injury during a playing season. Knowledge of the overhead throwing cycle is crucial for our understanding of these shoulder injuries. Baseball pitchers are prone to rotator cuff tears from tensile overload and impingement. Glenoid labrum degeneration or tears are also common, due to overuse syndrome (micro-instability), internal impingement and microtrauma. An understanding of the lesions involved in overhead throwing is crucial in baseball pitchers, as long-term disability can result from these injuries, sometimes with severe financial consequences to the player.

OBJECTIVE:The objective was to evaluate the use of fluorodeoxyglucose positron emission tomography (FDG-PET) in differentiating benign from malignant compression fractures. PATIENTS AND METHODS/METHODS:In a retrospective analysis, we identified 33 patients with 43 compression fractures who underwent FDG-PET. On FDG-PET the uptake pattern was recorded qualitatively and semiquantitatively and fractures were categorized as benign or malignant. Standardized uptake values (SUV) were obtained. MRI, CT, and biopsy results as well as clinical follow-up for 1-3 years served as standards of reference. The Student's t test was used to determine whether there was a statistically significant difference between the SUV for benign and malignant compression fractures. RESULTS:There were 14 malignant and 29 benign compression fractures, including 5 acute benign fractures. On FDG-PET, 5 benign fractures were falsely classified as malignant (false-positive). Three of these patients underwent prior treatment with bone marrow-stimulating agents. There were two false-negative results. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FDG-PET in differentiating benign from malignant compression fractures were 86%, 83%, 84%, 71%, and 92% respectively. The difference between SUV values of benign and malignant fractures was statistically significant (1.9 +/- 0.97 for benign and 3.9 +/- 1.52 for malignant fractures, p < 0.001). SUV of benign acute and chronic fractures were not statistically significant. CONCLUSION/CONCLUSIONS:Fluorodeoxyglucose positron emission tomography is useful in differentiating benign from malignant compression fractures. Therapy with bone marrow-stimulating agents can mimic malignant involvement.

OBJECTIVE:The purpose of our study was to determine the MRI features of metatarsal head subchondral fractures in symptomatic adults. MATERIALS AND METHODS/METHODS:A retrospective review of foot MRI procedures was performed to detect cases of metatarsal head subchondral fractures over a 6-year period. MR images of selected cases were analyzed by two reviewers for the presence of subchondral fracture, marrow edema-like pattern, metatarsal head flattening, and subchondral sclerosis. Patients with a history of foot surgery, infection, or inflammatory arthritis were excluded. Assessment for coexisting osseous and soft-tissue abnormalities was also performed. RESULTS:Subchondral fractures of the metatarsal heads were seen in 14 patients. All patients were women. The metatarsal head most commonly affected was the second (71%, 10/14) and the dorsal third of the metatarsal articular surface was involved in 79% (11/14). MRI findings of subchondral fracture of the metatarsal head with severe marrow edema-like pattern were seen in 71% (10/14), suggesting early stage changes. Metatarsal head collapse with subchondral sclerosis and mild or absent marrow edema-like pattern were seen in 29% (4/14) indicating late-stage changes. Concurrent abnormalities included three patients (21%) with metatarsal shaft fractures and one patient (7%) with an interdigital neuroma. One subject was treated surgically. CONCLUSION/CONCLUSIONS:Subchondral fractures of the metatarsal heads can be detected on MR examinations of adults with forefoot pain. A subchondral fracture with associated marrow edema-like pattern is the most common presentation and likely reflects early stages of metatarsal head infraction.

OBJECTIVE:The objective was to describe the imaging and histopathologic characteristics of metastatic myxoid liposarcomas. MATERIALS AND METHODS/METHODS:This retrospective study was approved by the institutional review board and complied with HIPAA guidelines. The study group comprised 12 patients with metastatic myxoid liposarcoma who underwent MRI, CT, or FDG-PET. The location and imaging characteristics of the metastatic lesions were recorded, and the histopathology of all metastatic lesions was reviewed. RESULTS:There were 23 histologically proven metastases in 12 patients. Based on imaging criteria, there were 41 metastases. The mean time from the diagnosis of primary tumor to the first metastasis was 4.4 years. Sixty-seven percent of patients had bone and soft tissue metastases, 33% had pulmonary metastases, 33% had liver metastases, 25% had intra-abdominal, and 16% retroperitoneal metastases. CT demonstrated well-defined lobulated masses with soft tissue attenuation in all cases, without macroscopic fat component. In cases of osseous metastases, CT showed mixed lytic and sclerotic foci, with bone destruction in advanced cases. MRI demonstrated fluid-like signal intensity with mild heterogeneous enhancement in cases of soft tissue metastases. In osseous metastases, MRI showed avid heterogeneous enhancement. FDG-PET showed no significant FDG uptake for all metastases. MRI was the most useful imaging modality for osseous and soft tissue metastases. CONCLUSION/CONCLUSIONS:Myxoid liposarcomas are soft tissue sarcomas, with a high prevalence of extrapulmonary metastases. The bones and soft tissues were the most common site of involvement, followed by the lungs and liver. MRI was the most sensitive modality in the detection of osseous and soft tissue metastases, and is the recommended modality for the diagnosis and follow-up of bone and soft tissue involvement.

Baseball pitcher throwing biomechanics are important to understanding the pathophysiology and magnetic resonance (MR) imaging appearances of injuries in baseball pitchers. Baseball pitchers experience repetitive excessive valgus forces at the elbow. Typical injuries are secondary to medial joint distraction, lateral joint compression, and rotatory forces at the olecranon. MR imaging is useful for evaluation of the elbow in baseball pitchers.