External validation of a convolutional neural network algorithm for opportunistically detecting vertebral fractures in routine CT scans.

The Convolutional Neural Network algorithm achieved a sensitivity of 94% and specificity of 93% in identifying scans with vertebral fractures (VFs). The external validation results suggest that the algorithm provides an opportunity to aid radiologists with the early identification of VFs in routine CT scans of abdomen and chest. PURPOSE: To evaluate the performance of a previously trained Convolutional Neural Network (CNN) model to automatically detect vertebral fractures (VFs) in CT scans in an external validation cohort. METHODS: Two Chinese studies and clinical data were used to retrospectively select CT scans of the chest, abdomen and thoracolumbar spine in men and women aged ≥50 years. The CT scans were assessed using the semiquantitative (SQ) Genant classification for prevalent VFs in a process blinded to clinical information. The performance of the CNN model was evaluated against reference standard readings by the area under the receiver operating characteristics curve (AUROC), accuracy, Cohen's kappa, sensitivity, and specificity. RESULTS: A total of 4,810 subjects were included, with a median age of 62 years (IQR 56-67), of which 2,654 (55.2%) were females. The scans were acquired between January 2013 and January 2019 on 16 different CT scanners from three different manufacturers. 2,773 (57.7%) were abdominal CTs. A total of 628 scans (13.1%) had ≥1 VF (grade 2-3), representing 899 fractured vertebrae out of a total of 48,584 (1.9%) visualized vertebral bodies. The CNN's performance in identifying scans with ≥1 moderate or severe fractures achieved an AUROC of 0.94 (95% CI: 0.93-0.95), accuracy of 93% (95% CI: 93%-94%), kappa of 0.75 (95% CI: 0.72-0.77), a sensitivity of 94% (95% CI: 92-96%) and a specificity of 93% (95% CI: 93-94%). CONCLUSION: The algorithm demonstrated excellent performance in the identification of vertebral fractures in a cohort of chest and abdominal CT scans of Chinese patients ≥50 years.

Update on Quantitative Computed Tomography.

Quantitative computed tomography (QCT) has important technical advantages for the measurement of bone mineral density, and the technique is well suited for both the diagnosis of osteoporosis and the monitoring of treatment. Its use deserves a wider application than at present. The use of QCT in both research and in the clinic has recently garnered increasing attention. In this review, we update the advances and application of QCT in the study of osteoporosis.

Assessment of 3.0 Tesla magnetic resonance imaging in Madelung's deformity: findings and implications.

OBJECTIVE: The aim of the study was to investigate the 3.0 Tesla magnetic resonance imaging (MRI) features of Madelung's deformity. MATERIALS AND METHODS: The wrist MRI scans of 19 patients clinically diagnosed with Madelung's deformity and 20 patients without deformity were consecutively selected from Beijing Jishuitan Hospital between April 2019 and December 2022 for observation, in the case group and control group, respectively. Multiple linear regression was used to analyze the factors affecting tilting angle and width of central disc (CD, also termed as triangular fibrocartilage, the main component of triangular fibrocartilage complex), while the chi-square test was used to compare the occurrences of CD (radial) attachment displacement, VL, and RTL. p < 0.05 indicated statistical significance. RESULTS: Madelung's deformity significantly contributed to the tilting and thickening of the CD. In the case group, the tilting angle and thickness of CD were (51.46 ± 1.33)° and (0.23 ± 0.01) cm, respectively, which was statistically significant (p < 0.05); the radial attachment of the CD significantly shifted away from the distal articular surface level (χ2 = 39.00, p < 0.001), with a mean displacement of (0.97 ± 0.38) cm. Furthermore, the cases demonstrated abnormally developed Vickers ligament (χ2 = 35.19, p < 0.001) and radiotriquetral ligament (χ2 = 25.66, p < 0.001). CONCLUSION: MRI provides a notable advantage in diagnosing Madelung's deformity. Compared with the control group, patients with Madelung's deformity exhibited tilting and thickening of the CD. Additionally, the radial attachment of the CD was significantly shifted proximally with abnormal development of Vickers and radiotriquetral ligaments.

Low muscle density in children with osteogenesis imperfecta using opportunistic low-dose chest CT: a case-control study.

BACKGROUND: The aim of the study was to investigate the muscle differences in children with osteogenesis imperfecta (OI) using opportunistic low-dose chest CT and to compare different methods for the segmentation of muscle in children. METHODS: This single center retrospective study enrolled children with OI and controls undergoing opportunistic low-dose chest CT obtained during the COVID pandemic. From the CT images, muscle size (cross-sectional area) and density (mean Hounsfield Units [HU]) of the trunk muscles were measured at the mid-T4 and the mid-T10 level using two methods, the fixed thresholds and the Gaussian mixture model. The Bland-Altman method was also used to compute the strength of agreement between two methods. Comparison of muscle results between OI and controls were analyzed with Student t tests. RESULTS: 20 children with OI (mean age, 9.1 ± 3.3 years, 15 males) and 40 age- and sex-matched controls were enrolled. Mean differences between two methods were good. Children with OI had lower T4 and T10 muscle density than controls measured by the fixed thresholds (41.2 HU vs. 48.0 HU, p < 0.01; 37.3 HU vs. 45.9 HU, p < 0.01). However, children with OI had lower T4 muscle size, T4 muscle density, T10 muscle size and T10 muscle density than controls measured by the Gaussian mixture model (110.9 vs. 127.2 cm2, p = 0.03; 44.6 HU vs. 51.3 HU, p < 0.01; 72.6 vs. 88.0 cm2, p = 0.01; 41.6 HU vs. 50.3 HU, p < 0.01, respectively). CONCLUSIONS: Children with OI had lower trunk muscle density indicating that OI might also impair muscle quality. Moreover, the fixed thresholds may not be suitable for segmentation of muscle in children.

Inter-rater variability and repeatability in the assessment of the Tanner-Whitehouse classification of hand radiographs for the estimation of bone age.

OBJECTIVE: To determine which bones and which grades had the highest inter-rater variability when employing the Tanner-Whitehouse (T-W) method. MATERIALS AND METHODS: Twenty-four radiologists were recruited and trained in the T-W classification of skeletal development. The consistency and skill of the radiologists in determining bone development status were assessed using 20 pediatric hand radiographs of children aged 1 to 18 years old. Four radiologists had a poor concordance rate and were excluded. The remaining 20 radiologists undertook a repeat reading of the radiographs, and their results were analyzed by comparing them with the mean assessment of two senior experts as the reference standard. Concordance rate, scoring, and Kendall's W were calculated to evaluate accuracy and consistency. RESULTS: Both the radius, ulna, and short finger (RUS) system (Kendall's W = 0.833) and the carpal (C) system (Kendall's W = 0.944) had excellent consistency, with the RUS system outperforming the C system in terms of scores. The repeatability analysis showed that the second rating test, performed after 2 months of further bone age assessment (BAA) practice, was more consistent and accurate than the first. The capitate had the lowest average concordance rate and scoring, as well as the lowest overall concordance rate for its D classification. Moreover, the G classifications of the seven carpal bones all had a concordance rate less than 0.6. The bones with lower Kendall's W were likewise those with lower scores and concordance rates. CONCLUSION: The D grade of the capitate showed the highest variation, and the use of the Tanner-Whitehouse 3rd edition (T-W3) to determine bone age (BA) was frequently inconsistent. A more comprehensive description with a focus on inaccuracy bones or ratings and a modification to the T-W3 approach would significantly advance BAA.

Assessing osteoporosis in postmenopausal women: preliminary results using a novel lumbar spine phantom-based MRI scoring method.

OBJECTIVE: To develop a novel magnetic resonance imaging (MRI) phantom for producing F-score (for fat) and W-score (for water) and to evaluate the performance of these scores in assessing osteoporosis and related vertebral fractures. MATERIALS AND METHODS: First, a real-time phantom consisting of oil and water tubes was manufactured. Then, 30 female volunteers (age: 62.3 ± 6.3 years) underwent lumbar spine examination with MRI (using a novel phantom) and dual-energy X-ray absorptiometry (DXA), following ethical approval. MRI phantom-based F-score and W-score were defined by normalizing the vertebral signal intensities (SIs) by the oil and water SIs of the phantom on T1- and T2-weighted images, respectively. The diagnostic performances of the new scores for assessing osteoporosis and vertebral fractures were examined using receiver operating characteristic analysis and compared with DXA-measured areal bone mineral density (DXA-aBMD). RESULTS: The F-score and W-score were greater in the osteoporotic patients (3.93 and 2.29) than the non-osteoporotic subjects (3.05 and 1.79) and achieved AUC values of 0.85 and 0.74 (p < 0.05), respectively, when detecting osteoporosis. Similarly, F-score and W-score had greater values for the fracture patients (3.94 and 2.53) than the non-fracture subjects (3.14 and 1.69) and produced better AUC values (0.90 for W-score and 0.79 for F-score) compared to DXA-aBMD (AUC: 0.27, p < 0.05). In addition, the F-score and W-score had a strong correlation (r = 0.77; p < 0.001). CONCLUSION: A novel real-time lumber spine MRI phantom was developed, based upon which newly defined F-score and W-score were able to detect osteoporosis and demonstrated an improved ability over DXA-aBMD in differentiating patients with vertebral fractures.

Greater bone marrow fat and myosteatosis are associated with lower vBMD but not asymptomatic vertebral fracture.

OBJECTIVES: Organ fat may affect bone metabolism and be associated with vertebral fracture (VF). This study aimed to explore relationships between VF, adiposity indexes measured by MRI, and volumetric BMD (vBMD) measured by quantitative CT (QCT). METHODS: Four hundred volunteers, ranging in age from 22 to 83 years, were recruited and underwent same-day abdominal QCT and chemical shift-encoded (CSE) MRI. We used MRI to quantify the fat content of bone marrow (BMF), psoas major and paraspinal muscles, and the liver. Abdominal fat, VF, and vBMD of the lumbar spine were measured by QCT. For VF discrimination analysis, we examined both the whole cohort (60 VF cases in 30 men and 30 women) and a restricted subgroup of those aged over 50 years (50 VF cases in 23 men and 27 women). RESULTS: Amongst the men, a 1 SD increase in BMF was associated with a 27.67 (95% CI, -32.71 to -22.62) mg/cm3 decrease in vBMD after adjusting for age and BMI. Amongst women, all adiposity indexes except for liver fat were significantly associated with vBMD, with BMF having the strongest association (ß, -24.00; 95% CI, -28.54 to -19.46 mg/cm3). Similar findings were also observed in participants aged over 50 years. The associations of adiposity indexes with vertebral fracture were not significant after adjusting for age in both sexes aged over 50 years. CONCLUSIONS: In both sexes, higher bone marrow fat was associated with lower vBMD at the spine. However, marrow fat and other adipose tissues were not associated with radiographic-based prevalent vertebral fractures. KEY POINTS: • In both sexes, higher bone marrow fat was associated with lower vBMD at the spine. • Among women, all adiposity indexes except for liver fat content were significantly associated with vBMD, with bone marrow fat having the strongest association. • Marrow fat and other adipose tissues were not associated with radiographic-based asymptomatic vertebral fractures.

The association of lumbar disc degeneration with lumbar vertebral trabecular volumetric bone mineral density in an urban population of young and middle-aged community-dwelling Chinese adults: a cross-sectional study.

INTRODUCTION: Lumbar intervertebral disc degeneration (LDD) and osteoporosis (OP) are age-related conditions that induce low back pain and have an impact on quality of life. The relationship between LDD and changes in bone mineral density (BMD) is, however, contentious and ever-changing. The purpose of this study is to investigate the relationship between lumbar vertebral volumetric BMD (vBMD) and LDD in an urban population of young and middle-aged community-dwelling Chinese adults. MATERIALS AND METHODS: 719 participants were recruited from among the subjects enrolled in a 10-year longitudinal study of degeneration of the spine and knee being conducted at the Beijing Jishuitan Hospital. The severity of LDD was graded using the five-grade Pfirrmann classification, and lumbar vertebral vBMD was measured using quantitative computed tomography (QCT). The relationship between the grade of intervertebral disc degeneration and lumbar vertebral vBMD was analyzed, and multiple linear regression was performed to adjust for covariates. RESULTS: The mean lumbar vBMD decreased as the grade of LDD increased (171.5 g/cm3, 147.8 g/cm3, and 124.3 g/cm3, respectively; P < 0.001). After adjusting for age, a higher LDD stage was associated with a lower mean L2-L4 vBMD, although a statistically significant correlation was observed only in men (standardized coefficient ß = - 0.656, P = 0.004). In men, there was a negative correlation between single-vertebra vBMD and degeneration of adjacent intervertebral discs, particularly those involving the L3 vertebra (L2-3 disc: ß = - 0.333, P < 0.001, L3-4 disc: ß = - 0.398, P < 0.001), as well as the mean grade of the L2-4 discs (ß = - 0.448, P < 0.001). However, the L5-S1 disc had a smaller correlation with age than others, and no statistically significant associations with lumbar vBMD were observed in either men (ß = - 0.024, P = 0.729) or women (ß = - 0.057, P = 0.396). CONCLUSION: Our study found that the degree of LDD was negatively associated with lumbar trabecular vBMD, although (excepting the L5-S1 disc), the relationship was statistically significant only in men.

Percentiles for paraspinal muscle parameters at the L3 vertebra level in patients undergoing lumbar computed tomography scanning.

BACKGROUND: Computed tomography (CT) is the gold standard for analyzing muscle parameters. PURPOSE: To clarify sex-specific paraspinal muscle area (PMA), paraspinal muscle index (PMI), and muscle fat infiltration (MFI) percentiles. MATERIAL AND METHODS: This was a cross-sectional study of 760 individuals (45% men; age range = 20-92 years; mean age = 53.4 ± 21.1 years) with a body mass index (BMI) in the range of 16.4-38.1 kg/m2. CT scans were retrospectively used to establish PMA, PMI, and MFI at L3 level using a deep-learning (DL) tool. Sex-specific distributions for these parameters were assessed based on associations between age/BMI and individual muscle parameters, after which age- and BMI-specific percentile estimates were determined. The 5th percentile was regarded as the cutoff for PMA/PMI, and the 95th percentile was regarded as the cutoff for MFI. RESULTS: Sex-specific PMA, PMI, and MFI cutoffs in the paraspinal muscles group were 52.9 cm2, 15.0 cm2/m2, and 33.3%, respectively, in men, and 33.2 cm2, 9.5 cm2/m2, and 41.2% in women. Age was moderately negatively correlated with PMA and was strongly negatively correlated with PMI, but age was strongly positively correlated with MFI. BMI was moderately positively correlated with PMA/PMI in men and strongly positively correlated in women; BMI was weakly positively correlated with MFI, thus enabling the establishment of age- and BMI-specific cutoff percentiles. CONCLUSION: Sex-specific PMA, PMI, and MFI percentiles and age- and BMI-specific cutoff values for these parameters were successfully established for an outpatient population.

Deep learning for automatic segmentation of paraspinal muscle on computed tomography.

BACKGROUND: Muscle quantification is an essential step in sarcopenia evaluation. PURPOSE: To develop and evaluate an automated machine learning (ML) algorithm for segmenting the paraspinous muscles on either abdominal or lumbar (L) computed tomography (CT) scans. MATERIAL AND METHODS: A novel deep neural network algorithm for automated segmentation of paraspinous muscle was developed, CT scans of 504 consecutive patients conducted between January 2019 and February 2020 were assembled. The muscle was manually segmented at L3 vertebra level by three radiologists as ground truth, divided into training and testing subgroups. Muscle cross-sectional area (CSA) was recorded. Dice similarity coefficients (DSCs) and CSA errors were calculated to evaluate system performance. The degree of muscle fat infiltration (MFI) recording by percentage value was the fat area within the region of interest divided by the muscle area. An analysis of the factors influencing the performance of the V-net-based segmentation system was also implemented. RESULTS: The mean DSCs for paraspinous muscles were high for both the training (0.963, 0.970, 0.941, and 0.968, respectively) and testing (0.950, 0.960, 0.929, and 0.961, respectively) datasets, while the CSA errors were low for both training (1.9%, 1.6%, 3.1%, and 1.3%, respectively) and testing (3.4%, 3.0%, 4.6%, and 1.9%, respectively) datasets. MFI and muscle area index (MI) were major factors affecting DSCs of the posterior paraspinous and paraspinous muscle groups. CONCLUSION: The ML algorithm for the measurement of paraspinous muscles was compared favorably to manual ground truth measurements.

The lumbar spinal endplate lesions grades and association with lumbar disc disorders, and lumbar bone mineral density in a middle-young general Chinese population.

BACKGROUND: Lumbar vertebral endplates lesions (LEPLs), one of the etiologies of low back pain (LBP), are one of the most prevalent causes of health-care costs. Despite progressively becoming the focus in recent years, almost all studies have concentrated on symptomatic patients rather than general populations. As a result, our study was designed to determine the prevalence and distribution patterns of LEPLs in a middle-young general population, as well as their associations with lumbar disc herniation (LDH), lumbar disc degeneration (LDD), and lumbar vertebral volumetric bone mineral density (vBMD). METHODS: Seven hundred fifty-four participants aged 20-60 years were recruited from the subjects enrolled in a 10-year longitudinal study of degeneration of the spine and knee being conducted at the Beijing Jishuitan Hospital and 4 of them were excluded due to the missing of MRIs. In this observational study, a lumbar quantitative computed tomography (QCT) and MRI scan were performed among participants within 48 h. T2-weighted sagittal lumbar MRI images for all included subjects were identified for LEPLs by two independent observers based on morphological and local characteristics. Lumbar vertebral vBMD was measured with QCT. The age, BMI, waistline, hipline, lumbar vBMD, LDD, and LDH were measured to investigate their associations with LEPLs. RESULTS: The prevalence of LEPLs was higher among the male subjects. 80% of endplates were recognition as no lesions with a substantial disparity between female (75.6%) and male subjects (83.4%) (p < 0.001). The most common lesions were "wavy/irregular" and "notched", and "fracture" is most involved in L3-4 inferior endplate both in two genders. LEPLs were found to be associated with LDH (≥ 2 levels: OR = 6.859, P < 0.001; 1 level: OR = 2.328, P = 0.002 in men. OR = 5.004, P < 0.001; OR = 1.805, P = 0.014 in women) reference for non-LDH, and hipline in men (OR = 1.123, P < 0.001). CONCLUSIONS: LEPLs are the common findings on lumbar MRIs in general population, particularly in men. The presence of these lesions and advance from slightly to severely could be mainly attributed to LDH and men's higher hipline.

Construction and Application of Rib Fracture Diagnosis Model Based on YOLOv3 Algorithm.

OBJECTIVES: The artificial intelligence-aided diagnosis model of rib fractures based on YOLOv3 algorithm was established and applied to practical case to explore the application advantages in rib fracture cases in forensic medicine. METHODS: DICOM format CT images of 884 cases with rib fractures caused by thoracic trauma were collected, and 801 of them were used as training and validation sets. A rib fracture diagnosis model based on YOLOv3 algorithm and Darknet53 as the backbone network was built. After the model was established, 83 cases were taken as the test set, and the precision rate, recall rate, F1-score and radiology interpretation time were calculated. The model was used to diagnose a practical case and compared with manual diagnosis. RESULTS: The established model was used to test 83 cases, the fracture precision rate of this model was 90.5%, the recall rate was 75.4%, F1-score was 0.82, the radiology interpretation time was 4.4 images per second and the identification time of each patient's data was 21 s, much faster than manual diagnosis. The recognition results of the model was consistent with that of the manual diagnosis. CONCLUSIONS: The rib fracture diagnosis model in practical case based on YOLOv3 algorithm can quickly and accurately identify fractures, and the model is easy to operate. It can be used as an auxiliary diagnostic technique in forensic clinical identification.

Diagnostic Role of Magnetic Resonance Imaging in Low Back Pain Caused by Vertebral Endplate Degeneration.

Low back pain (LBP) is a common health issue worldwide with a huge economic burden on healthcare systems. In the United States alone, the cost is estimated to be $100 billion each year. Intervertebral disc degeneration is considered one of the primary causes of LBP. Moreover, the critical role of the vertebral endplates in disc degeneration and LBP is becoming apparent. Endplate abnormalities are closely correlated with disc degeneration and pain in the lumbar spine. Imaging modalities such as plain film radiography, computed tomography, and fluoroscopy are helpful but not very effective in detecting the causes behind LBP. Magnetic resonance imaging (MRI) can be used to acquire high-quality three-dimensional images of the lumbar spine without using ionizing radiation. Therefore, it is increasingly being used to diagnose spinal disorders. However, according to the American College of Radiology, current referral and justification guidelines for MRI are not sufficiently clear to guide clinical practice. This review aimed to evaluate the role of MRI in diagnosing LBP by considering the correlative contributions of vertebral endplates. The findings of the review indicate that MRI allows for fine evaluations of endplate morphology, endplate defects, diffusion and perfusion properties of the endplate, and Modic changes. Changes in these characteristics of the endplate were found to be closely correlated with disc degeneration and LBP. The collective evidence from the literature suggests that MRI may be the imaging modality of choice for patients suffering from LBP. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 3.

Hepatic Steatosis: CT-Based Prevalence in Adults in China and the United States and Associations With Age, Sex, and Body Mass Index.

BACKGROUND. Calibrated CT fat fraction (FFCT) measurements derived from un-enhanced abdominal CT reliably reflect liver fat content, allowing large-scale population-level investigations of steatosis prevalence and associations. OBJECTIVE. The purpose of this study was to compare the prevalence of hepatic steatosis, as assessed by calibrated CT measurements, between population-based Chinese and U.S. cohorts, and to investigate in these populations the relationship of steatosis with age, sex, and body mass index (BMI). METHODS. This retrospective study included 3176 adults (1985 women and 1191 men) from seven Chinese provinces and 8748 adults (4834 women and 3914 men) from a single U.S. medical center, all drawn from previous studies. All participants were at least 40 years old and had undergone unenhanced abdominal CT in previous studies. Liver fat content measurements on CT were cross-calibrated to MRI proton density fat fraction measurements using phantoms and expressed as adjusted FFCT measurements. Mild, moderate, and severe steatosis were defined as adjusted FFCT of 5.0-14.9%, 15.0-24.9%, and 25.0% or more, respectively. The two cohorts were compared. RESULTS. In the Chinese and U.S. cohorts, the median adjusted FFCT for women was 4.7% and 4.8%, respectively, and that for men was 5.8% and 6.2%, respectively. In the Chinese and U.S. cohorts, steatosis prevalence for women was 46.3% and 48.7%, respectively, whereas that for men was 58.9% and 61.9%, respectively. Severe steatosis prevalence was 0.9% and 1.8% for women and 0.2% and 2.6% for men in the Chinese and U.S. cohorts, respectively. Adjusted FFCT did not vary across age decades among women or men in the Chinese cohort, although it increased across age decades among women and men in the U.S. cohort. Adjusted FFCT and BMI exhibited weak correlation (r = 0.312-0.431). Among participants with normal BMI, 36.8% and 38.5% of those in the Chinese and U.S. cohorts, respectively, had mild steatosis, and 3.0% and 1.5% of those in the Chinese and U.S. cohorts, respectively, had moderate or severe steatosis. Among U.S. participants with a BMI of 40.0 or greater, 17.7% had normal liver content. CONCLUSION. Steatosis and severe steatosis had higher prevalence in the U.S. cohort than in the Chinese cohort in both women and men. BMI did not reliably predict steatosis. CLINICAL IMPACT. The findings provide new information on the dependence of hepatic steatosis on age, sex, and BMI.

Accuracy, Linearity and Precision of Spine QCT vBMD Phantom Measurements for Different Brands of CT Scanner: A Multicentre Study.

We describe a multicenter study using the European Spine Phantom (ESP) to compare the accuracy, linearity and precision of QCT measurements of spine vBMD between different brands of scanner, different models of the same brand and identical units of the same model. Ten scans of the same ESP with repositioning were performed on forty CT scanners from five manufacturers in different hospitals across China, all calibrated with the Mindways QCT system. The three ESP vertebral bodies simulating low (L1), medium (L2) and high (L3) vBMD and their average (L1-3 vBMD) were compared with phantom values. Linearity was assessed using the standard error of the estimate derived from linear regression. Precision errors were expressed as the standard deviation of the ten measurements on each scanner. Median (IQR) vBMD over all forty CT scanners compared with phantom values were: L1: 52.2 (49.9-56.4) vs 51.0; L2: 104.4 (101.2-108.6) vs 102.2; L3: 201.4 (195.0-204.9) vs 200.4; L1-3: 119.3 (116.6-123.2) vs 117.9 mg/cm3. Statistically significant differences in L1-3 vBMD were found between different brands (p= 0.005) and between different models of the same brand and identical units of the same model (both p< 0.001). Cross-calibration using linear regression gave a good fit for all forty systems with a median standard error of the estimate of 1.7 mg/cm3. The median precision error for L1-3 vBMD was 0.61 mg/cm3. Statistically significant differences in spine vBMD measurements between different scanners reinforce the importance of cross-calibration in multi-center studies. Cross-calibration can be reliably performed using linear regression equations.

Magnetic resonance imaging of focal fibrocartilaginous dysplasia - findings derived from a three-dimensional gradient echo sequence.

BACKGROUND: Focal fibrocartilaginous dysplasia is a rare benign bone lesion of young children that causes deformities in the extremities. However, the pathogenesis and treatments have not been defined and the MR manifestations have been less well described. OBJECTIVE: To describe the MR manifestations of focal fibrocartilaginous dysplasia, especially on the T1-W three-dimensional (3-D) volumetric interpolated breath-hold examination (VIBE) sequence. MATERIALS AND METHODS: In this retrospective study, the authors reviewed the MR and radiographic images, pathology and medical records of 21 cases of focal fibrocartilaginous dysplasia. All cases were evaluated by spin-echo MRI sequence. Among them, 17 cases were evaluated by T1-W 3-D VIBE sequence. RESULTS: The cohort consisted of 13 boys and 8 girls ages 4-75 months. In 14 cases, focal fibrocartilaginous dysplasia was located in the tibia, 3 in the femur and 4 in the ulna. MRI 3-D VIBE sequence findings showed all cases had hypointense fiber band structures in the bone defect areas. The fibrous bands in the lower extremities ended in the epiphysis or epiphyseal plate, and in the upper extremities the epiphysis or carpal bone. Ten cases had hyperintensities that might represent cartilage composition. Four cases had cartilage signals that were continuous with the epiphyseal cartilage. MR spin-echo sequence findings showed that bone marrow edema of the adjacent joint was observed in eight cases, enlargement of the epiphyseal plate in three cases and medial meniscus injury in five cases. CONCLUSION: The 3-D VIBE sequence reveals useful details in focal fibrocartilaginous dysplasia.

In Vivo Assessment of Age- and Loading Configuration-Related Changes in Multiscale Mechanical Behavior of the Human Proximal Femur Using MRI-Based Finite Element Analysis.

BACKGROUND: MRI-based finite element analysis (MRI-FEA) is the only method able to assess microstructural and whole-bone mechanical properties of the hip in vivo. PURPOSE: To examine whether MRI-FEA is capable of discriminating age-related changes in whole-bone mechanical performance and micromechanical behavior of the proximal femur, particularly considering the most common hip fracture-related sideways fall loading. STUDY TYPE: Retrospective. SUBJECTS: A total of nine younger (27 ± 3.2 years) and nine elderly (61 ± 3.9 years) healthy volunteers. FIELD STRENGTH/SEQUENCE: 3T; 3D fast field echo sequence. ASSESSMENT: The left proximal femurs were scanned and FE models created. FEA was performed to simulate sideways fall and stance loading for each femoral model. Apparent stiffness and high-risk (90th percentile) tensile and compressive strains of the proximal femur as well as the average strains within cubic regions of the femoral neck and greater trochanter were assessed. STATISTICAL TESTS: Paired and unpaired t-tests. RESULTS: Compared to the young group, the femoral stiffness of the elderly decreased by 39% and 40% (both P < 0.05) under the sideways fall and stance conditions, respectively. Accordingly, the high-risk tensile and compressive stains were elevated with aging (40% and 23% for sideways fall, 23% and 11% for stance conditions; all P < 0.05). However, the loading configuration-induced difference was only observed in the elderly group for the high-risk strains (22% for tension and 12% for compression; both P < 0.05). Additionally, compared to the stance condition, the sideways fall increased the average tensile (young: 108%, elderly: 123%; both P < 0.05) and compressive strains (young: 631%, elderly: 617%, both P < 0.05) within the greater trochanter rather than the femoral neck region. DATA CONCLUSION: In vivo MRI-FEA is capable of capturing age-related changes in both apparent-level stiffness and tissue-level micromechanical behavior of the proximal femur. However, the effect of sideways fall loading might be better reflected by tissue-level micromechanics rather than apparent stiffness. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 1.

Structural Factors Associated With Femoral Neck Fractures and its Prediction in Chinese Males.

We have recently proposed a new approach to evaluate 2D femoral neck (FN) structure, named the Minimal Model (MM), that comprised FN areal bone mineral density (FNaBMD) and FNWidth and 2 new internal structural measures; (1) the standard deviation of normalized mineral mass projection profile distribution (FNSigma), and (2) the displacement between center-of-mineral mass and geometric center of mineral mass projection profile (FNDelta). The contralateral hip of 67 FN fracture Chinese male patients had a QCT scan shortly after fracture and was compared to 156 community participants without hip fracture. The QCT scans were analyzed using Mindways software to enable DXA-equivalent 2D images to be obtained; MM variables were calculated from these images. In FN fracture and nonfracture participants, the 4 MM variables as well as age, weight and height were compared. Compared to nonfracture, fracture participants were older, weighed less and were taller. After adjustment for these differences FN fracture participants compared to nonfracture had mean ± SD lower FNaBMD 0.54 ± 0.11 vs 0.70 ± 0.11 g/cm2 (p < 0.001); larger FNSigma 1.05 ± 0.11 vs 0.98 ± 0.10 cm (p < 0.001); larger FNDelta 0.43 ± 0.09 vs 0.33 ± 0.09 cm (p < 0.001), however FNWidth did not differ 2.96 ± 0.35 vs 2.92 ± 0.34 cm. All variables except FNaBMD and FNWidth were correlated; however logistic regression identified increased age and height, reduced FNaBMD and increased FNSigma as independent contributors to differentiating participants with FN fracture from nonfracture. Area under ROC analysis identified significant improvement in discrimination with addition of FNSigma to the base model of Age and FNaBMD (C statistic 0.88 and 0.91, p = 0.019). These analyses identified important internal structural information available from 2D DXA imaging that contributes to discrimination of FN fracture in addition to low bone mass. This analytical approach may contribute to improved clinical FN fracture prediction, extending value of widely available DXA technology.

Volume of White Matter Hyperintensities, and Cerebral Micro-Bleeds.

PURPOSE: In the past years the significance of white matter hyperintensities (WMH) has gained raising attention because it is considered a marker of severity of different pathologies. Another condition that in the last years has been assessed in the neuroradiology field is cerebral microbleeds (CMB). The purpose of this work was to evaluate the association between the volume of WMH and the presence and characteristics of CMB. MATERIAL AND METHODS: Sixty-five consecutive (males 45; median age 70) subjects were retrospectively analyzed with a 1.5 Tesla scanner. WMH volume was quantified with a semi-automated procedure considering the FLAIR MR sequences whereas the CMB were studied with the SWI technique and CMBs were classified as absent (grade 1), mild (grade 2; total number of CMBs: 1-2), moderate (grade 3; total number of CMBs: 3-10), and severe (grade 4; total number of CMBs: >10). Moreover, overall number of CMBs and the maximum diameter were registered. RESULTS: Prevalence of CMBs was 30.76% whereas WMH 81.5%. Mann-Whitney test showed a statistically significant difference in WMH volume between subjects with and without CMBs (p < 0.001). Pearson analysis showed significant correlation between CMB grade, number and maximum diameter and WMH. The better ROC area under the curve (Az) was obtained by the hemisphere volume with a 0.828 (95% CI from 0.752 to 0,888; SD = 0.0427; p value = 0.001). The only parameters that showed a statistically significant association in the logistic regression analysis were Hemisphere volume of WMH (p = 0.001) and Cholesterol LDL (p = 0.0292). CONCLUSION: In conclusion, the results of this study suggest the presence of a significant correlation between CMBs and volume of WMH. No differences were found between the different vascular territories.

Liver Fat Content Measurement with Quantitative CT Validated against MRI Proton Density Fat Fraction: A Prospective Study of 400 Healthy Volunteers.

Background Although chemical shift-encoded (CSE) MRI proton density fat fraction (PDFF) is the current noninvasive reference standard for liver fat quantification, the liver is more frequently imaged with CT. Purpose To validate quantitative CT measurements of liver fat against the MRI PDFF reference standard. Materials and Methods In this prospective study, 400 healthy participants were recruited between August 2015 and July 2016. Each participant underwent same-day abdominal unenhanced quantitative CT with a calibration phantom and CSE 3.0-T MRI. CSE MRI liver fat measurements were used to calibrate an equation to adjust CT fat measurements and put them on the PDFF measurement scale. CT and PDFF liver fat measurements were plotted as histograms, medians, and interquartile ranges compared; scatterplots and Bland-Altman plots obtained; and Pearson correlation coefficients calculated. Receiver operating characteristic curves including areas under the curve were evaluated for mild (PDFF, 5%) and moderate (PDFF, 14%) steatosis thresholds for both raw and adjusted CT measurements. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. Results Four hundred volunteers (mean age, 52.6 years ± 15.2; 227 women) were evaluated. MRI PDFF measurements of liver fat ranged between 0% and 28%, with 41.5% (166 of 400) of participants with PDFF greater than 5%. Both raw and adjusted quantitative CT values correlated well with MRI PDFF (r2 = 0.79; P < .001). Bland-Altman analysis of adjusted CT values showed no slope or bias. Both raw and adjusted CT had areas under the receiver operating characteristic curve of 0.87 and 0.99, respectively, to identify participants with mild (PDFF, >5%) and moderate (PDFF, >14%) steatosis, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value for unadjusted CT was 75.9% (126 of 166), 85.0% (199 of 234), 78.3% (126 of 161), and 83.3% (199 of 239), respectively, for PDFF greater than 5%; and 84.8% (28 of 33), 98.4% (361 of 367), 82.4% (28 of 34), and 98.6% (361 of 366), respectively, for PDFF greater than 14%. Results for adjusted CT were mostly identical. Conclusion Quantitative CT liver fat exhibited good correlation and accuracy with proton density fat fraction measured with chemical shift-encoded MRI. © RSNA, 2019 Online supplemental material is available for this article.