First intention vertebroplasty in fractures within an ankylosed thoracolumbar spinal segment

PURPOSE

To evaluate the outcome of percutaneous vertebral cementoplasty (PVC) as the first-line treatment for traumatic thoracolumbar fractures within an ankylosed spinal segment.

MATERIALS AND METHODS

Thirty-one patients (15 men, 16 women; mean age: 79.2±11 [SD] years; age range: 66-95 years) with thoracolumbar fractures within an ankylosed spine segment without neurological impairment treated with PVC were retrospectively evaluated. All patients were controlled at six weeks and one year after PVC. Ankylosing conditions, fractures sites and types, radiological consolidation, spinal complications were assessed. Anterior/posterior vertebral height ratios were measured before and after PVC. Postoperative pain relief and treatment success (radiological fracture consolidation) rates were considered.

RESULTS

The 31 patients had a total of 39 fractures (19 stable [49%], 20 unstable [51%]) treated with PVC. Primary success rate of PVC (initial fracture consolidation without complication) was 61% (19/31). Seven patients (7/31; 23%) exhibited new fractures, and the secondary success rate of PVC (global fracture consolidation one year after repeat PVC) was 87% (34/39). Global consolidation rates of unstable fractures were 85% (17/20) of treated levels. Pain score was null in 84% patients (26/31) one year after PVC. There were no significant differences between pre-PVC (0.62±0.18 [SD]; range: 0.22-0.88) and post-PVC (0.60±0.18 [SD]; range: 0.35-0.88) vertebral height ratios (P=0.94).

CONCLUSION

PVC conveys a high overall success rate and effectively controls pain in patients with vertebral fractures within ankylosed spine segments.

Usefulness of Trabecular CT Attenuation Measurement of Lumbar Spine in Predicting Osteoporotic Compression Fracture: Is the L4 Trabecular Region of Interest Most Relevant?

STUDY DESIGN

Retrospective study.

OBJECTIVE

The aim of this study was to evaluate the usefulness of computed tomography (CT) attenuation in defining trabecular region-of-interest (t-ROI) at lumbar vertebral body in the assessment of osteoporotic compression fracture (OCF) compared to spinal dual x-ray absorptiometry (DXA).

SUMMARY OF BACKGROUND DATA

Even though osteoporosis was not diagnosed in the bone mineral density measurement using DXA, we often experienced cases where the screw was weakly inserted due to low bone quality during screw insertion.

METHODS

A total of 188 patients who met the inclusion criteria were enrolled. We determined best cutoff value of the simple t-ROI attenuation at the most relevant level for predicting OCF. We assessed correlations between the simple t-ROI attenuation at the most relevant level and OCF rate, and investigate the association between the number of compression fracture and simple t-ROI attenuation at the most relevant level.

RESULTS

L4 ROI attenuation is the most accurate measurement for predicting osteoporotic compression fracture with an area under the curve of 0.798. The optimal cutoff point of L4 ROI attenuation was measured at 90.5 HU with 88.8% and 60.6% sensitivity and specificity, respectively. L4 ROI attenuation was significantly correlated with the osteoporotic compression fracture rate (r = -0.545, P < 0.001). The number of compression fracture (coefficient of determination R2 = 0.286; P < 0.001) was independently correlated with L4 ROI attenuation.

CONCLUSION

Simple t-ROI computed tomography attenuation is an accurate measurement tool in predicting OCF compared to DXA T-score. The value of L4 t-ROI attenuation is the most relevant measurement for predicting osteoporotic compression fracture, is an alternative to DXA, and can predict the number and rate of compression fractures. Spine surgeons should be aware of L4 t-ROI attenuation to make successful fusion in spine surgery for elderly patients group.Level of Evidence: 3.

Using opportunistic screening with abdominal CT to identify osteoporosis and osteopenia in patients with diabetes

Opportunistic osteoporosis screening involves measuring the attenuation of L1 vertebrae on abdominal computed tomography (CT), which correlates with DXA T-score. We found that this approach is useful for detecting low bone mass in patients with diabetes and propose L1 attenuation ≤ 135 Hounsfield units (HU) as a threshold for which DXA should be strongly considered.

INTRODUCTION

Attenuation of the L1 vertebrae on computer tomography (CT) images done for other reasons ("Opportunistic Osteoporosis Screening") has been found to correlate well with DXA-derived T-score. However, the method and the thresholds have never been tested specifically in those with diabetes mellitus (DM), in whom the fracture risk is greater than explained by BMD.

METHODS

In a retrospective study of subjects with DM who had both abdominal CT and DXA within 6 months of each other, we compared L1 attenuation and DXA T-score to define the sensitivity and specificity of thresholds previously established in the general population.

RESULTS

There were 313 subjects among whom 18 (5.8%) had prior major osteoporotic fracture (MOF). Subjects with MOF had lower T-scores (- 2.3 ± 1.4 vs. - 0.9 ± 1.4, p < 0.001) and L1 attenuation (104 HU ± 46 vs. 149 HU ± 47, p < 0.001) than non-fracture subjects. L1 attenuation ≤ 160 HU was 91% sensitive for osteoporosis, while ≤ 110 HU was 80% specific. For a higher T-score of ≤ - 1.5, L1 attenuation ≤ 135 HU showed balanced sensitivity and specificity (65% and 69%, respectively).

CONCLUSION

Opportunistic osteoporosis screening with abdominal CT is useful in determining the need for DXA screening in subjects with diabetes. We propose L1 attenuation ≤ 135 HU as a reasonable threshold for detecting the T-score of ≤ - 1.5, which is likely associated with increased fragility in DM.

Opportunistic use of chest CT for screening osteoporosis and predicting the risk of incidental fracture in breast cancer patients: A retrospective longitudinal study

This study aimed to investigate the diagnostic performance of chest computed tomography (CT) for opportunistic screening and longitudinal follow-up of osteoporosis in breast cancer patients, compared to dual-energy X-ray absorptiometry (DXA). The association between L1 vertebral attenuation on chest CT and incidental fracture was also evaluated. We retrospectively reviewed 414 consecutive breast cancer patients who underwent both non-enhanced chest CT and DXA within a 3-month interval and had at least two DXA and two chest CT examinations over more than 1 year. The attenuation value of the L1 trabecular bone was measured on an axial CT image and compared to the corresponding DXA T-score. The diagnostic performance of L1 vertebral attenuation on CT for osteoporosis was calculated at different thresholds (90 HU, 100 HU, 110 HU), and the correlation between L1 vertebral attenuation values and DXA T-scores was statistically analyzed. Overall fracture-free survival was estimated and compared with the threshold of 90 HU on CT and -2.5 T-score on DXA. Of 414 patients (median age, 53.0 years), 88 (21.3%) had either vertebral or non-vertebral fractures. The median follow-up duration between initial and final DXA was 902.9 days. There was a moderate correlation between L1 vertebral attenuation value and DXA T-score (ρ = 0.684, CI 0.653–0.712). Fracture-free survival was significantly lower in patients with attenuation values ≤90 HU on CT and T-scores ≤-2.5 on DXA (P < .001). Multivariate analysis revealed that attenuation values ≤90 HU on CT (P < .001), T-scores ≤-2.5 on DXA (P = .003), and age ≥65 years (P = .03) were independent significant prognostic factors associated with overall fracture-free survival. The sensitivities and specificities of L1 attenuation value were 54.9% and 85.8% at 90-HU threshold, 74.0% and78.4% at 100-HU threshold, and 83.9% and 70.1% at 110-HU threshold, respectively. In conclusion, CT can be used for predicting osteoporosis and discriminating incidental fracture risk in breast cancer patients.

The Value of Quantitative Musculoskeletal Imaging

Musculoskeletal imaging is mainly based on the subjective and qualitative analysis of imaging examinations. However, integration of quantitative assessment of imaging data could increase the value of imaging in both research and clinical practice. Some imaging modalities, such as perfusion magnetic resonance imaging (MRI), diffusion MRI, or T2 mapping, are intrinsically quantitative. But conventional morphological imaging can also be analyzed through the quantification of various parameters. The quantitative data retrieved from imaging examinations can serve as biomarkers and be used to support diagnosis, determine patient prognosis, or monitor therapy.

We focus on the value, or clinical utility, of quantitative imaging in the musculoskeletal field. There is currently a trend to move from volume- to value-based payments. This review contains definitions and examines the role that quantitative imaging may play in the implementation of value-based health care. The influence of artificial intelligence on the value of quantitative musculoskeletal imaging is also discussed.

Predicting Bone Marrow Edema and Fracture Age in Vertebral Fragility Fractures Using MDCT

OBJECTIVE. The purpose of this study was to evaluate whether CT features can predict bone marrow edema (BME) on MRI and fracture age in vertebral fragility fractures. MATERIALS AND METHODS. A total of 189 thoracolumbar compression fractures in 103 patients (14 men, 89 women; mean age, 76 years) imaged with both spine CT and MRI were retrospectively included. The presence and extent of BME were assessed on MRI to divide fractures into those with and without BME. The group with BME was then classified for subgroup analysis into fractures with extensive BME (comprising 50% or more of the vertebral body) and those with BME comprising less than 50% of the vertebral body. On CT, five features (presence of cortical or endplate fracture line, presence of trabecular fracture line, presence of condensation band, change in trabecular attenuation, and width of paravertebral soft-tissue change) were analyzed. RESULTS. All five CT findings were predominantly seen in fractures with BME (p < 0.001). Elevated trabecular attenuation, presence of a cortical or endplate fracture line, and paravertebral soft-tissue width showed excellent diagnostic indication for fractures with BME (ROC AUCs: 0.990, 0.976, and 0.950, respectively). In the subgroup with extensive BME, paravertebral soft-tissue width was significantly higher, whereas the change in trabecular attenuation was lower compared with those with BME comprising less than 50% of the vertebral body (p < 0.001). When BME was present, fracture age was not significantly different between the two subgroups, and only greater trabecular attenuation elevation was predictive of older fracture age on linear mixed model analyses (p < 0.001). Interobserver agreement was good for the trabecular fracture line factor and excellent for all other factors. CONCLUSION. CT features accurately correlate with the presence and extent of BME in vertebral fragility fractures. Elevation of trabecular attenuation was the only significant image predictor of fracture age.

The association between lower Hounsfield units of the upper instrumented vertebra and proximal junctional kyphosis in adult spinal deformity surgery with a minimum 2-year follow-up

OBJECTIVE

Patients undergoing long-segment fusions from the lower thoracic (LT) spine to the sacrum for adult spinal deformity (ASD) correction are at risk for proximal junctional kyphosis (PJK). One mechanism of PJK is fracture of the upper instrumented vertebra (UIV) or higher (UIV+1), which may be related to bone mineral density (BMD). Because Hounsfield units (HUs) on CT correlate with BMD, the authors evaluated whether HU values were correlated with PJK after long fusions for ASD.

METHODS

The authors performed a retrospective study of patients older than 50 years who had undergone ASD correction from the LT spine to the sacrum in the period from October 2007 to January 2018 and had a minimum 2-year follow-up. Demographic and spinopelvic parameters were measured. HU values were measured on preoperative CT at the UIV, UIV+1, and UIV+2 (2 levels above the UIV) levels and were assessed for correlations with PJK.

RESULTS

The records of 127 patients were reviewed. Fifty-four patients (19 males and 35 females) with a mean age of 64.91 years and mean follow-up of 3.19 years met the study inclusion criteria; there were 29 patients with PJK and 25 patients without. There was no statistically significant difference in demographics or follow-up between these two groups. Neither was there a difference between the groups with regard to postoperative pelvic incidence (PI), sacral slope (SS), lumbar lordosis (LL), PI minus LL (PI-LL), thoracic kyphosis (TK), or sagittal vertical axis (SVA; all p > 0.05). Postoperative pelvic tilt (p = 0.003) and T1 pelvic angle (p = 0.014) were significantly higher in patients with PJK than in those without. Preoperative HUs at UIV, UIV+1, and UIV+2 were 120.41, 124.52, and 129.28 in the patients with PJK, respectively, and 152.80, 155.96, and 160.00 in the patients without PJK, respectively (p = 0.011, 0.02, and 0.018). Three receiver operating characteristic (ROC) curves for preoperative HU values at the UIV, UIV+1, and UIV+2 as a predictor for PJK were established, with areas under the ROC curve of 0.710 (95% CI 0.574–0.847), 0.679 (95% CI 0.536–0.821), and 0.681 (95% CI 0.539–0.824), respectively. The optimal HU value by Youden index was 104 HU at the UIV (sensitivity 0.840, specificity 0.517), 113 HU at the UIV+1 (sensitivity 0.720, specificity 0.517), and 110 HU at the UIV+2 (sensitivity 0.880, specificity 0.448).

CONCLUSIONS

In patients undergoing long-segment fusions from the LT spine to the sacrum for ASD, PJK was associated with lower HU values on CT at the UIV, UIV+1, and UIV+2. The measurement of HU values on preoperative CTs may be a useful adjunct for ASD surgery planning.

Practical management of fracture risk among peri- and postmenopausal women

Fractures and their consequences are the clinically important manifestation of osteoporosis; preventing fractures is the primary goal of management. Effective management is achievable given present knowledge and tools but is seldom prescribed. This review will cover the individual and social burden of fracture, essential information about fracture risk and its estimation, an approach to patient care emphasizing specific information to elicit and therapeutic strategies to pursue, and existing gaps in knowledge and important questions for future research.

Effects of intra-articular corticosteroid injections on lumbar trabecular density

PURPOSE

To determine the effect of intra-articular corticosteroid injections on lumbar spine trabecular density.

MATERIALS AND METHODS

This retrospective study was IRB-approved and HIPAA-compliant. We identified 50 patients (26 F, 24 M, mean age 69 ± 14 years) who had undergone at least three medium or large joint corticosteroid injections using insoluble corticosteroids and a subsequent non-contrast abdominal CT within 5 years of the first injection. About 126 age- and sex-matched controls without history of prior corticosteroid use who had undergone non-contrast abdominal CT were identified. Cumulative corticosteroid dose was calculated. Density measurements (HU) of trabecular bone of L1 to L4 were performed, and measurements of L1 were compared to established normative data. Groups were compared using a two-sided paired t-test or a chi-squared test. Linear regression analysis between cumulative corticosteroid dose and trabecular density was performed.

RESULTS

Patients underwent a mean of 4 corticosteroid injections (range 3 to 11) with a mean cumulative corticosteroid dose of 232 ± 100 mg triamcinolone equivalent (range 120 mg to 480 mg). There was no significant difference in trabecular density of L1 to L4 between cases and controls, and there was no significant difference in trabecular density at L1 compared to normative data (p > 0.2). There was no association between cumulative intra-articular corticosteroid dose and mean lumbar trabecular density (p > 0.3).

CONCLUSION

Patients who underwent repetitive intra-articular insoluble corticosteroid injections showed no increased risk of bone loss compared to controls. Cumulative intra-articular corticosteroid dose was not associated with lumbar trabecular density.

Current Concepts in the Management of Vertebral Compression Fractures

PURPOSE OF REVIEW

This comprehensive review of current concepts in the management of vertebral compression fractures is a manuscript of vertebral augmentation literature of risk factors, clinical presentation, and management. The objective of this review is to compare outcomes between multiple augmentation techniques and ongoing discussions of effectiveness of vertebral augmentation procedures.

RECENT FINDINGS

Vertebral compression fractures (VCFs) are a prevalent disease affecting approximately 1.5 million US adults annually. VCFs can cause severe physical limitations, including back pain, functional disability, and progressive kyphosis of the thoracic spine that ultimately results in decreased appetite, poor nutrition, impaired pulmonary function, and spinal cord compression with motor and sensory deficits. The deconditioning that affects patients with vertebral compression fractures leads to mortality at a far higher rate than age-matched controls. The management of vertebral compression fractures has been extensively discussed with opponents arguing in favor or restricting conservative management and against augmentation, while proponents argue in favor of augmentation. The literature is well established in reference to the effects on mortality when patients undergo treatment with vertebral augmentation; in over a million patients with vertebral compression fractures treated with vertebral augmentation as compared with patients treated with non-surgical management, the patients receiving augmentation performed well with a decrease in morbidity and mortality. Summary of the literature review shows that understanding the risk factors, appropriate clinical evaluation, and management strategies are crucial. Analysis of the evidence shows, based on level I and II studies, balloon kyphoplasty had significantly better and vertebroplasty tended to have better pain reduction compared with non-surgical management. In addition, balloon kyphoplasty tended to have better height restoration than vertebroplasty.

Characteristics of vertebral CT Hounsfield units in elderly patients with acute vertebral fragility fractures

OBJECTIVE

To explore the characteristics of vertebral CT Hounsfield units (HU) in elderly patients with acute vertebral fragility fractures.

METHODS

A total of 299 patients aged ≥ 65 years with acute vertebral fragility fractures were retrospectively reviewed, and 77 patients of them were age- and sex-matched with 77 control patients without any fractures. The vertebral HU value of L1(L1-HU) was measured, and T12 and L2 were used as alternatives for L1 in the case of L1 fracture.

RESULTS

There were 460 thoracic and lumbar vertebral fractures in the 299 elderly patients, including 349 acute vertebral fragility fractures and 111 chronic fractures. The average L1-HU value was 66.0 ± 30.6 HU and showed significant difference among patients having different numbers of vertebral fractures (one fracture: 73.3 ± 27.0 HU, two fractures: 58.7 ± 32.5 HU, three or more fractures: 40.7 ± 28.8 HU; P < 0.001). As for the 1:1 age- and sex-matched patients, the L1-HU of the 77 patients with fractures was lower than that of the control patients (70.6 ± 23.4 HU vs. 101.5 ± 36.2 HU, P < 0.001). The area under the receiver operating characteristic curve of using L1-HU to differentiate patients with fractures from controls was 0.77(95% CI 0.70-0.85, P < 0.001). The cutoff value had high specificity of 90% or high sensitivity of 90% to identify patients with fractures of 60 HU and 100 HU, respectively.

CONCLUSIONS

The elderly patients with acute vertebral fragility fractures have much lower HU values than those without fractures. Moreover, the lower the vertebral HU value is, the more likely the patients have more than one vertebral fracture. These slides can be retrieved under Electronic Supplementary Material.

Incidental identification of vertebral compression fractures in patients over 60 years old using computed tomography scans showing the entire thoraco-lumbar spine

INTRODUCTION

Vertebral compression fractures (VCF) are frequently asymptomatic; incidental diagnosis is a valuable opportunity to identify low bone mass and to start treatment. We aimed to determine the proportion of patients over 60 years old evaluated with chest plus abdominal and pelvic computed tomography (CT) scans, allowing visualization of the entire thoraco-lumbar spine, who incidentally present VCF.

MATERIALS AND METHODS

We evaluated 300 patients over 60 years old who under went chest plus abdominal and pelvic CT scans. Using sagittal reformats we looked for VCF using the method described by Genant. Accordingly, VCF were classified into mild, moderate or severe. We also determined the percentage of VCF described in the radiological reports.

RESULTS

In our cohort [median age 72.5 years (61-94)], 45.67% were males and 54.33% were females. In total, 43 patients (14.33%) had at least one VCF; 32 (10.67%) had one VCF, whereas 11 (3.67%) exhibited multiple VCF, with a total of 84 fractures. 42 were mild fractures, 29 moderate and 13 severe. The proportion of males (13.87%) and females (14.72%) with VCF was not different (p = 0.83). Patients with VCF were older than those without VCF (p < 0.01). Only age but not sex was independently associated with the presence of VCF. Only 32.56% of patients we identified as having a VCF had a description in their report (14 patients).

CONCLUSION

An important proportion of patients over 60 years old evaluated with chest plus abdominal and pelvic CT scans present VCF. The reporting of these VCF is insufficient; radiologists and clinicians should include their detection in their search pattern.

Use of Bone Health Evaluation in Orthopedic Surgery: 2019 ISCD Official Position

This position development conference (PDC) Task Force examined the assessment of bone status in orthopedic surgery patients. Key questions included which orthopedic surgery patients should be evaluated for poor bone health prior to surgery and which subsets of patients are at high risk for poor bone health and adverse outcomes. Second, the reliability and validity of using bone densitometry techniques and measurement of specific geometries around the hip and knee before and after arthroplasty was determined. Finally, the use of computed tomography (CT) attenuation coefficients (Hounsfield units) to estimate bone quality at anatomic locations where orthopedic surgery is performed including femur, tibia, shoulder, wrist, and ankle were reviewed. The literature review identified 665 articles of which 198 met inclusion exclusion criteria and were selected based on reporting of methodology, reliability, or validity results. We recommend that the orthopedic surgeon be aware of established ISCD guidelines for determining who should have additional screening for osteoporosis. Patients with inflammatory arthritis, chronic corticosteroid use, chronic renal disease, and those with history of fracture after age 50 are at high risk of osteoporosis and adverse events from surgery and should have dual energy X-ray absorptiometry (DXA) screening before surgery. In addition to standard DXA, bone mineral density (BMD) measurement along the femur and proximal tibia is reliable and valid around implants and can provide valuable information regarding bone remodeling and identification of loosening. Attention to positioning, selection of regions of interest, and use of special techniques and software is required. Plain radiographs and CT provide simple, reliable methods to classify the shape of the proximal femur and to predict osteoporosis; these include the Dorr Classification, Cortical Index, and critical thickness. Correlation of these indices to central BMD is moderate to good. Many patients undergoing orthopedic surgery have had preoperative CT which can be utilized to assess regional quality of bone. The simplest method available on most picture archiving and communications systems is to simply measure a regions of interest and determine the mean Hounsfield units. This method has excellent reliability throughout the skeleton and has moderate correlation to DXA based on BMD. The prediction of outcome and correlation to mechanical strength of fixation of a screw or implant is unknown.

Vertebral bone attenuation in Hounsfield Units and prevalent vertebral fractures are associated with the short-term risk of vertebral fractures in current and ex-smokers with and without COPD: a 3-year chest CT follow-up study

CT scans performed to evaluate chronic obstructive pulmonary disease (COPD) also enable evaluation of bone attenuation (BA; a measure of bone density) and vertebral fractures (VFs). In 1239 current/former smokers with (n = 999) and without (n = 240) COPD, the combination of BA and prevalent VFs was associated with the incident VF risk.

INTRODUCTION

Chest CT scans are increasingly used to evaluate pulmonary diseases, including COPD. COPD patients have increased risk of osteoporosis and VFs. BA on CT scans is correlated with bone mineral density and prevalent VFs. The aim of this study was to evaluate the association between BA and prevalent VFs on chest CT scans, and the risk of incident VFs in current and former smokers with and without COPD.

METHODS

In participants of the ECLIPSE study with baseline and 1-year and 3-year follow-up CT scans, we evaluated BA in vertebrae T₄-T₁₂ and prevalent and incident VFs.

RESULTS

A total of 1239 subjects were included (mean age 61.3 ± 8.0, 61.1% men, 999 (80.6%) COPD patients). The mean BA was 155.6 ± 47.5 Hounsfield Units (HU); 253 (20.5%) had a prevalent VF and 296 (23.9%) sustained an incident VF within 3 years. BA and prevalent VFs were associated with incident VFs within 1 (per - 1SD HR = 1.38 [1.08-1.76] and HR = 3.97 [2.65-5.93] resp.) and 3 years (per - 1SD HR = 1.25 [1.08-1.45] and HR = 3.10 [2.41-3.99] resp.), while age, sex, body mass index (BMI), smoking status and history, or presence of COPD was not. In subjects without prevalent VFs and BA, and for 1-year incidence, BMI values were associated with incident fractures (1 year, BA per - 1SD HR = 1.52 [1.05-2.19], BMI per SD HR = 1.54 [1.13-2.11]; 3 years, per - 1SD HR = 1.37 [1.12-1.68]).

CONCLUSIONS

On CT scans performed for pulmonary evaluation in (former) smokers with and without COPD, the combination of BA and prevalent VFs was strongly associated with the short-term risk of incident VFs.

Opportunistic Osteoporosis Screening at Routine Abdominal and Thoracic CT: Normative L1 Trabecular Attenuation Values in More than 20 000 Adults

Background Abdominal and thoracic CT provide a valuable opportunity for osteoporosis screening regardless of the clinical indication for imaging. Purpose To establish reference normative ranges for first lumbar vertebra (L1) trabecular attenuation values across all adult ages to measure bone mineral density (BMD) at routine CT. Materials and Methods Reference data were constructed from 20 374 abdominal and/or thoracic CT examinations performed at 120 kV. Data were derived from adults (mean age, 60 years ± 12 [standard deviation]; 56.1% [11 428 of 20 374] women). CT examinations were performed with (n = 4263) or without (n = 16 111) intravenous contrast agent administration for a variety of unrelated clinical indications between 2000 and 2018. L1 Hounsfield unit measurement was obtained either with a customized automated tool (n = 11 270) or manually by individual readers (n = 9104). The effects of patient age, sex, contrast agent, and manual region-of-interest versus fully automated L1 Hounsfield unit measurement were assessed using multivariable logistic regression analysis. Results Mean L1 attenuation decreased linearly with age at a rate of 2.5 HU per year, averaging 226 HU ± 44 for patients younger than 30 years and 89 HU ± 38 for patients 90 years or older. Women had a higher mean L1 attenuation compared with men (P < .008) until menopause, after which both groups had similar values. Administration of intravenous contrast agent resulted in negligible differences in mean L1 attenuation values except in patients younger than 40 years. The fully automated method resulted in measurements that were average 21 HU higher compared with manual measurement (P < .004); at intrapatient subanalysis, this difference was related to the level of transverse measurement used (midvertebra vs off-midline level). Conclusion Normative ranges of L1 vertebra trabecular attenuation were established across all adult ages, and these can serve as a quick reference at routine CT to identify adults with low bone mineral density who are at risk for osteoporosis. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Smith in this issue.

Opportunistic bone density screening for the abdominal radiologist using colored CT images: a pilot retrospective study

PURPOSE

The purpose of the study was to develop an accurate and reproducible method for detecting low spinal bone density on abdominal CT images.

METHODS

For this IRB-approved HIPAA-compliant single-center retrospective study, nonenhanced CT images of the lower abdomen were obtained in 631 African-American participants. Mean attenuation of L3/L4 was associated with quantitative CT bone density (QCT) in a randomly selected training cohort (N = 511), and receiver operating characteristics analysis was used to identify the optimal mean attenuation threshold for differentiating normal from low bone density. Custom image processing software was used to generate grayscale and colored CT images of the midline spine, with green for normal and red for low bone density. Five radiologists independently assessed bone density at L3/L4 in a validation cohort (N = 120) using various methods: QCT, visual assessment of sagittal grayscale images (Grayscale), quantitative measurement of mean attenuation on a midline sagittal image (Attenuation), and visual assessment of a midline sagittal colored image (Color). Accuracy was calculated using the average QCT bone density as a reference standard. Inter-observer agreement was assessed using intraclass correlation coefficient (ICC).

RESULTS

The optimal mean attenuation threshold for differentiating normal from low bone density at L3/L4 was 145 Hounsfield Units. The average accuracy of Grayscale, Attenuation, and Color methods was 58, 87, and 91% (p < 0.001), respectively. Inter-observer agreement was poor for Grayscale (ICC: 0.20; 95% CI 0.12, 0.28) and excellent for both Attenuation (ICC: 0.85; 95% CI 0.73, 0.91) and Color methods (ICC: 0.87; 95% CI 0.83, 0.90).

CONCLUSION

Detection of low spinal bone density using colored abdominal CT images was highly accurate and reproducible.

Population-based opportunistic osteoporosis screening: Validation of a fully automated CT tool for assessing longitudinal BMD changes

METHODS:

The automated BMD tool was retrospectively applied to non-contrast abdominal CT scans in 1603 consecutive asymptomatic adults (mean age, 55.9 years; 770 M/833 F) undergoing longitudinal screening (mean interval, 5.7 years; range, 1.0-12.3 years). The spinal column was automatically segmented, with standardized L1 and L2 anterior trabecular ROI placement. Automated and manual L1 HU values were compared, as were automated supine-prone measures. L1-L2 CT attenuation values were converted to BMD values through a linear regression model. BMD values and changes were assessed according to age and gender.

RESULTS:

Success rate of the automated BMD tool was 99.8 % (four failed cases). Both automated supine vs prone and manual vs automated L1 attenuation measurements showed good agreement. Overall mean annual rate of bone loss was greater in females than males (-2.0% vs -1.0%), but the age-specific rate declined faster in females from age 50 (-2.1%) to age 65 (-0.3%) compared with males (-0.9% to -0.5%). Mean BMD was higher in females than males at age 50 (143.6 vs 135.1  mg cm^-3), but post-menopausal bone loss in females reversed this relationship beyond age 60. By age 70, mean BMD in females and males was 100.8 and 107.7  mg cm^-3 , respectively.

CONCLUSION:

This robust, fully automated CT BMD tool allows for both individualized and population-based assessment. Mean BMD was lower in men than women aged 50-60, but accelerated post-menopausal bone loss in women resulted in lower values beyond age 60.

ADVANCES IN KNOWLEDGE:

This fully automated tool can be applied to routine abdominal CT scans for prospective or retrospective opportunistic BMD assessment, including change over time. Mean BMD was lower in men compared with women aged 50-60 years, but accelerated bone loss in women during this early post-menopausal period resulted in lower BMD values for women beyond age 60.

Opportunistic Screening for Osteoporosis Using Computed Tomography: State of the Art and Argument for Paradigm Shift

PURPOSE OF REVIEW

Osteoporosis is disproportionately common in rheumatology patients. For the past three decades, the diagnosis of osteoporosis has benefited from well-established practice guidelines that emphasized the use of dual x-ray absorptiometry (DXA). Despite these guidelines and the wide availability of DXA, approximately two thirds of eligible patients do not undergo testing. One strategy to improve osteoporosis testing is to employ computed tomography (CT) examinations obtained as part of routine patient care to "opportunistically" screen for osteoporosis, without additional cost or radiation exposure to patients. This review examines the role of opportunistic CT in the evaluation of osteoporosis.

RECENT FINDINGS

Recent evidence suggests that opportunistic measurement of bone attenuation (radiodensity) using CT has sensitivity comparable to DXA. More importantly, such an approach has been shown to predict osteoporotic fractures. The paradigm shift of using CTs obtained for other reasons to opportunistically screen for osteoporosis promises to substantially improve patient care.

Opportunistic screening for osteoporosis in abdominal computed tomography for Chinese population

This study assessed the possibility of diagnosing and excluding osteoporosis with routine abdominal CT scans in a Chinese population who underwent both DXA and CT for unrelated reasons. Statistical correlation was made between the HU measured of the spine on CT and various parameters on DXA. Diagnostic cutoff points in terms of HU were established for the diagnosis (≤ 136 HU) and exclusion (≥ 175 HU) of osteoporosis on sagittal reformatted images. There was excellent positive and negative predictive value for the DXA-defined diagnostic subgroups and were also comparable with previous studies in Caucasian populations. The authors exhort radiologists to report these incidental findings to facilitate early detection and treatment of osteoporosis in unsuspecting patients to prevent fractures and related complications.

PURPOSE

The suspicion for osteoporosis can be raised in diagnostic computed tomography of the abdomen performed for other indications. We derived cutoff thresholds for the attenuation value of the lumbar spinal vertebrae (L1-5) in Hounsfield units (HU) in a Chinese patient population to facilitate implementation of opportunistic screening in radiologists.

METHODS

We included 109 Chinese patients who concomitantly underwent abdominal CT and dual X-ray absorptiometry (DXA) within 6 months between July 2014 and July 2017 at a university hospital in Hong Kong. Images were retrospectively reviewed on sagittal reformats, and region-of-interest (ROI) markers were placed on the anterior portion of each of the L1-L5 vertebra to measure the HU. The mean values of CT HU were then compared with the bone mineral density (BMD) and T-score obtained by DXA. Receiver operator characteristic (ROC) curves were generated to determine diagnostic cutoff thresholds and their sensitivity and specificity values.

RESULTS

The mean CT HU differed significantly (p < 0.01) for the three DXA-defined BMD categories of osteoporosis (97 HU), of osteopenia (135 HU), and of normal individuals (230 HU). There was good correlation between the mean CT HU and BMD and T-score (Pearson coefficient of 0.62 and 0.61, respectively, p < 0.001). The optimal cutoff point for exclusion of osteoporosis or osteopenia was HU ≥ 175 with negative predictive value as 98.9% and with area under curve (AUC) of ROC curve as 0.97. The optimal cutoff point for diagnosis of osteoporosis was HU ≤ 136 with positive predictive value as 81.2% and with AUC of ROC curve as 0.86.

CONCLUSION

This is the first study on osteoporosis diagnosis with routine CT abdominal scans in Chinese population. The cutoff values were comparable with previous studies in Caucasian populations suggesting generalizability. Radiologists should consider routinely reporting these opportunistic findings to facilitate early detection and treatment of osteoporosis to prevent fractures and related complications.

Deep neural networks for automatic detection of osteoporotic vertebral fractures on CT scans

Osteoporotic vertebral fractures (OVFs) are prevalent in older adults and are associated with substantial personal suffering and socio-economic burden. Early diagnosis and treatment of OVFs are critical to prevent further fractures and morbidity. However, OVFs are often under-diagnosed and under-reported in computed tomography (CT) exams as they can be asymptomatic at an early stage. In this paper, we present and evaluate an automatic system that can detect incidental OVFs in chest, abdomen, and pelvis CT examinations at the level of practicing radiologists. Our OVF detection system leverages a deep convolutional neural network (CNN) to extract radiological features from each slice in a CT scan. These extracted features are processed through a feature aggregation module to make the final diagnosis for the full CT scan. In this work, we explored different methods for this feature aggregation, including the use of a long short-term memory (LSTM) network. We trained and evaluated our system on 1432 CT scans, comprised of 10,546 two-dimensional (2D) images in sagittal view. Our system achieved an accuracy of 89.2% and an F1 score of 90.8% based on our evaluation on a held-out test set of 129 CT scans, which were established as reference standards through standard semiquantitative and quantitative methods. The results of our system matched the performance of practicing radiologists on this test set in real-world clinical circumstances. We expect the proposed system will assist and improve OVF diagnosis in clinical settings by pre-screening routine CT examinations and flagging suspicious cases prior to review by radiologists.

Future Osteoporotic Fracture Risk Related to Lumbar Vertebral Trabecular Attenuation Measured at Routine Body CT

We sought to determine if vertebral trabecular attenuation values measured on routine body computed tomography (CT) scans obtained for a variety of unrelated indications can predict future osteoporotic fractures at multiple skeletal sites. For this Health Insurance Portability and Accountability Act (HIPAA)-compliant and Institutional Review Board (IRB)-approved retrospective cohort study, trabecular attenuation of the first lumbar vertebra was measured in 1966 consecutive older adults who underwent chest and/or abdominal CT at a single institution over the course of 1 year. New pathologic fragility fractures that occurred after a patient's CT study date were identified through an electronic health record database query using International Classification of Diseases (ICD)-9 codes for vertebral, hip, and extremity fractures. Univariate and multivariate Cox proportional hazards regression were performed to determine the effect of L₁ trabecular attenuation on fracture-free survival. Age at CT, sex, and presence of a prior fragility fracture were included as confounders in multivariate survival analysis. Model discriminative capability was assessed through calculation of an optimism-corrected concordance index. A total of 507 patients (mean age 73.4 ± 6.3 years; 277 women, 230 men) were included in the final analysis. The median post-CT follow-up interval was 5.8 years (interquartile range 2.1-11.0 years). Univariate analysis showed that L₁ attenuation values ≤90 Hounsfield units (HU) are significantly associated with decreased fracture-free survival (p < 0.001 by log-rank test). After adjusting for age, sex, prior fracture, glucocorticoid use, bisphosphonate use, chronic kidney disease, tobacco use, ethanol abuse, cancer history, and rheumatoid arthritis history, multivariate analysis demonstrated a persistent modest effect of L₁ attenuation on fracture-free survival (hazard ratio [HR] = 0.63 per 10-unit increase; 95% confidence interval [CI] 0.47-0.85). The model concordance index was 0.700. Ten-year probabilities for major osteoporosis-related fractures straddled the treatment threshold for most subcohorts over the observed L₁ HU range. In conclusion, for patients undergoing body CT scanning for any indication, L₁ vertebral trabecular attenuation is a simple measure that, when ≤90 HU, identifies patients with a significant decrease in fracture-free survival. © 2018 American Society for Bone and Mineral Research.

Opportunistic Bone Density Measurement on Abdomen and Pelvis Computed Tomography to Predict Fracture Risk in Women Aged 50 to 64 Years Without Osteoporosis Risk Factors

OBJECTIVE

The aim of this study is to evaluate opportunistic vertebral bone density measurement in abdominal and pelvic computed tomography (CT) to predict future osteoporotic fracture in women aged 50 to 64 years without known osteoporosis risk factors.

METHODS

Consecutive female patients 50 to 64 years old without osteoporosis risk factors with 2 CT examinations more than 10 years apart were included. Vertebral height and bone density in each vertebra from T10 to L5 were measured. Vertebral fractures were diagnosed on CT preformed 10 years after the original CT and through online medical records.

RESULTS

Thirty (15%) of 199 patients developed osteoporotic fracture. Bone density was lower in patients who developed fractures compared with those who did not (P < 0.05). Development of osteoporotic fracture of any grade was predicted for patients having bone density less than 180 HU at L4 with sensitivity of 90% (95% confidence interval, 74%-97%) and specificity of 43% (95% confidence interval, 34%-50%).

CONCLUSIONS

Opportunistic bone density screening can identify women at elevated risk of developing fractures within 10 years.