Although measuring vertebral bone density with the use of the computed tomography-based Hounsfield units (HU) is becoming increasingly popular, a much-desired standardized and robust method for measuring HU values accurately, quickly and conveniently was yet to exist.

Lumbar CT images of patients with degenerative lumbar diseases were analyzed. The HU values of the vertebral bodies were measured in three planes: mid-axial (including or not including the posterior venous plexus (PVP)), mid-sagittal and mid-frontal; the HU values of the vertebral pedicles were measured in two planes: axial and sagittal. The existing method was improved to measure the HU values of the S1 pedicles. A comparative analysis was performed, the inter- and intra-observer agreements were calculated.

The HU values of the lumbar vertebrae in the mid-axial planes were the highest (p < 0.001), but showed the most reliable, reproducible and stable values of the intra-class correlation coefficient (ICC) (0.80-0.99 for vertebral bodies and 0.80-0.94 for pedicles). Non-inclusion of the PVP in the ROI did not affect HU values (p > 0.05), and the measurement of the HU values on a slice with the PVP showed high reproducibility (the ICC was 0.93-0.94). Measuring the HU values of the S1 pedicles with the use of the improved method led to an increase in ICC from 0.48 to 0.68.

Measuring HU values in the L3 alone rather than in the entire lumbar spine or other vertebrae works up to expectations and may be recommended. The ROI should be placed in the mid-axial plane on a slice including the PVP. The most challenging HU measurement is for the S1 pedicles, but the proposed improved method makes it easier to do. These considerations may be particularly relevant to spinal surgeons in their routine practice, including planning the lumbar fusion and screw fixation.

The subsidence of vertebral body replacement may occur after anterior cervical corpectomy and fusion (ACCF), which may lead to cervical kyphosis, spinal cord compression, and neurological dysfunction. The authors aim to investigate the risk factors for early subsidence of 3D-printed artificial vertebral body (3D-PAVB) after ACCF surgery and to provide guidance for clinical practice.

A retrospective analysis was conducted on the data of consecutive patients with cervical spondylosis who underwent ACCF surgery at Bethune Hospital of Shanxi from 2017 to 2020. The statistical data included age, gender, disease type, body mass index, surgical segment, vertebral height, Cobb angle, and Hounsfield unit (HU) values of the vertebral body and endplate. The clinical efficacy of the surgery was evaluated using Visual Analog Scale (VAS), Japanese Orthopedic Association (JOA), and Neck Disability Index (NDI). Follow-up data, such as VAS, JOA, NDI, and Cobb angle, were obtained using a repeated-measures analysis of variance analysis. Univariate analysis was conducted to identify the factors contributing to the early subsidence of the 3D-PAVB, and independent risk factors were determined using logistic regression. The HU value was analyzed using the receiver operating characteristic curve and the area under the curve to predict the subsidence of the 3D-PAVB.

A total of 66 patients were included in the study, of which 19 patients experienced subsidence of 3D-PAVB, resulting in an incidence rate of 28.8%. The postoperative JOA, VAS, and NDI scores showed significant improvement in both the subsidence and nonsubsidence groups. Upon conducting univariate analysis, significant differences were observed between the 2 groups in terms of age, diabetes, smoking, and lower vertebral computed tomography (CT) values. The average HU value of the subsidence group (251.39 ± 52.615, n = 19) was significantly lower than that of the nonsubsidence group (317.06 ± 73.587, n = 47, P < 0.01). Multivariate analysis revealed that smoking and HU of the lower vertebra were independent risk factors for 3D-PAVB subsidence, with an area under the curve of 0.772 and an optimal threshold of 272 for HU (sensitivity 78.9% and specificity 74.5%).

The occurrence of early subsidence of 3D-PAVB post ACCF surgery is influenced by 2 independent risk factors: smoking and low HU. To predict the likelihood of this outcome, it is advisable to consider smoking history and measure CT HU value prior to surgery. A lower CT HU value is indicative of a greater risk of subsidence.

Cervical spine fracture-dislocations in patients with ankylosing spondylitis (AS) are mostly unstable and require surgery. However, osteoporosis, one of the comorbidities for AS, could lead to detrimental prognoses. There are few accurate assessments of bone mineral density in AS patients.

To analyze Hounsfield units (HUs) for assessing bone mineral density in AS patients with cervical fracture-dislocation.

The HUs from C2 to C7 of 51 patients obtained from computed tomography (CT) scans and three-dimensional reconstruction of the cervical spine were independently assessed by two trained spinal surgeons and statistically analyzed. Inter-reader reliability and agreement were assessed by interclass correlation coefficient.

The HUs decreased gradually from C2 to C7. The mean values of the left and right levels were significantly higher than those in the middle. Among the 51 patients, 25 patients (49.02%) may be diagnosed with osteoporosis, and 16 patients (31.37%) may be diagnosed with osteopenia.

The HUs obtained by cervical spine CT are feasible for assessing bone mineral density with excellent agreement in AS patients with cervical fracture-dislocation.

Low bone mineral density (BMD) can predispose to vertebral body compression fractures and postoperative instrumentation failure. DEXA is considered the gold standard for measurement of BMD, however it is not obtained for all spine surgery patients preoperatively. There is a growing body of evidence suggesting that more routinely acquired spine imaging studies such as computed tomography (CT) and magnetic resonance imaging (MRI) can be opportunistically used to measure BMD. Here we review available studies that assess the validity of opportunistic screening with CT-derived Hounsfield Units (HU) and MRI-derived vertebral vone quality (VBQ) to measure BMD of the spine as well the utility of these measures in predicting postoperative outcomes. Additionally, we provide screening thresholds based on HU and VBQ for prediction of osteopenia/ osteoporosis and postoperative outcomes such as cage subsidence, screw loosening, proximal junctional kyphosis, and implant failure.

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Primary purpose was to assess changes of bone mineral density (BMD) in diffuse large B cell lymphoma (DLBCL) patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone R-CHOP (like) chemotherapy regimen. Secondary purposes were to assess other body composition features changes and to assess the association of pre-therapy values and their changes over time with survival.

Patients selected underwent R-CHOP(like) regimen for DLBCL, and underwent PET-CT before and after treatment. Main clinical data collected included body mass index, date of last follow-up, date of progression, and date of death. From the low-dose CT images, BMD was assessed at the L1 level; the other body composition values, including muscle and fat distribution, were assessed at the L3 level by using a dedicated software. Descriptive statistics were reported as median and interquartile range, or frequencies and percentages. Statistical comparisons of body composition variables between pre- and post-treatment assessments were performed using the Wilcoxon matched pairs signed rank test. Non-normal distribution of variables was tested with the Shapiro-Wilk test. For qualitative variables, the Fisher exact test was used. Log rank test was used to compare survival between different subgroups of the study population defined by specific body composition cutoffs. The significance level was set at p < 0.05.

Eighty-two patients were included. The mean follow-up was 37.5 ± 21.4 months. A significant difference was found in mean BMD before and after R-CHOP(like) treatment (p < 0.0001). The same trend was observed for mean skeletal muscle area (SMA) (p = 0.004) and mean skeletal muscle index (SMI) (p = 0.006). No significant association was demonstrated between body composition variables, PFS and OS.

R-CHOP(like) treatment in DLBCL patients was associated with significant reduction of BMD, SMA and SMI.

Computed tomography-based vertebral attenuation values (CT-based HU) have been shown to correlate with T-scores on DEXA scan; and have been acknowledged as an independent factor for predicting fragility fractures. Most patients undergoing lumbar surgeries require CT as part of their preoperative evaluation.

The current study was thus planned to evaluate the role of lumbar CT as an opportunistic investigation in determining BMD preoperatively in patients undergoing lumbar fusion.

Prospective cohort study.

Patients older than 45 years, who underwent one- to two-level lumbar (L3-S1 levels) fusions.

Comparison of the quantitative assessment of osteoporosis using Hounsfield Units (HU) on CT (L1-L5) and mean lumbar T-scores on DEXA (Dual Energy X-ray Absorptiometry).

HU on CT is comparable to T-score on DEXA as a suitable modality for the assessment of osteoporosis in patients undergoing one- to two-level lumbar fusion.

A prospective cohort study was conducted between January and December 2021. Patients older than 45 years, who underwent one- to two-level lumbar (L3-S1 levels) fusions and had complete clinico-radiological records, were prospectively enrolled. A comparison was drawn between the HU (measured by placing an oval region of interest [ROI] over axial, sagittal and coronal images of lumbar vertebrae) on CT and T-scores on DEXA, and analyzed statistically. The HU values correlating best with normal (group A), osteopenia (B) and osteoporosis (C) categories (classified based on T-scores of lumbar spines) were determined statistically.

Overall, 87 patients (mean age of 60.56±11.63 years; 63 [72.4%] female patients) were prospectively studied. There was a statistically significant difference in the mean age (p=.01) and sex distribution (predominantly female patients; p=.03) of patients belonging to groups B (osteopenic) and C (osteoporotic patients), as compared with group A. The greatest correlation between T-score (on DEXA) and HU (on CT) for differentiating osteopenia (group B) from group A was observed at levels L1 (p<.001), L2 (p<.001) and L3 (p<.001). Based on receiver-operating characteristic (ROC) curve analysis, the cut-off values for HU for identifying osteopenia were 159 (at L1; sensitivity 81.6 and specificity 80) and 162 (at L2; sensitivity 80 and specificity 71.1). In addition, there was statistically significant correlation between T-score (on DEXA) and HU at all the lumbar levels for distinguishing osteoporosis (group C), although the difference was most evident at the upper lumbar (L1 and L2) levels (p<.001). Based on ROC analysis, cut-off HU values for defining osteoporosis were 127 (at L1; sensitivity 71.3 and specificity 70) and 117 (at L2; sensitivity 65.5 and specificity 90).

Based on our study, the measurement of HU on CT at upper lumbar levels can be considered as "surrogate marker" for BMD in the diagnosis of osteopenia (cut-off: 159 at L1, 162 at L2) and osteoporosis (cut-off: 127 at L1, 117 at L2) in patients undergoing lumbar fusion surgeries. The HU measurements on CT at the lower lumbar levels (L4 and L5) are less reliable in this preoperative scenario.

To investigate whether in radiographic axial spondyloarthritis (r-axSpA) inflammation is associated with lower trabecular bone density (TBD), and subsequently, if a lower TBD increases the likelihood of 2-year bone formation at the same vertebra.

Whole spine (C3-L5) data from patients included in the multicentre 2-year Sensitive Imaging in Ankylosing Spondylitis cohort was used. Two readers measured baseline TBD by Hounsfield units (HU) on low-dose CT (ldCT). Baseline MRI bone marrow oedema (BME) status scores and ldCT syndesmophyte formation and/or growth change-from-baseline scores were assessed by three and two readers, respectively. Average of readers' continuous measurements or readers' agreement in binary scores generated within the same vertebra (1-present in ≥1 quadrant/0-absent in all quadrants) were used. Multilevel generalised estimating equations models were used, the unit of analysis being the vertebra.

In 50 patients with r-axSpA, TBD HU decreased from cranial to caudal vertebrae. Baseline MRI-BME was present in 300/985 (30%) and syndesmophytes in 588/910 (65%) vertebrae, both most prevalent at thoracolumbar region. Syndesmophyte formation or growth was observed in 18% of at-risk vertebrae (124/691). A significant confounder-adjusted association was found between inflammation and lower TBD (regression coefficient=-51; 95% CI-63 to -39). TBD was not associated with 2-year syndesmophyte formation or growth (adjusted OR 1.00; 95% CI 0.99 to 1.00).

In r-axSpA, while vertebral inflammation was associated with lower vertebral TBD, lower vertebral TBD itself did not increase the risk for new bone formation at the same vertebra. In preventing syndesmophyte progression, targeting local inflammation seems more important than targeting vertebral trabecular bone loss.

To describe low dose Computed Tomography (ldCT) Hounsfield Units (HU) two-year change-from-baseline values (expressing trabecular bone density changes) and analyse their inter-reader reliability per vertebra in radiographic axial spondyloarthritis (r-axSpA).

We used 49 patients with r-axSpA from the multicentre two-year Sensitive Imaging in Ankylosing Spondylitis (SIAS) study. LdCT HU were independently measured by two trained readers at baseline and two years. Mean (standard deviation, SD) for the change-from-baseline HU values were provided per vertebra by reader. Intraclass correlation coefficients (ICC; absolute agreement, two-way random effect), Bland-Altman plots and smallest detectable change (SDC) were obtained. Percentages of vertebrae in which readers agreed on the direction of change and on change >|SDC| were computed.

Overall, 1,053 (98% of all possible) vertebrae were assessed by each reader both at baseline and two years. Over two years, HU mean change values varied from -23 to 28 and 29 for reader 1 and 2, respectively. Inter-reader reliability of the two-year change-from-baseline values per vertebra was excellent: ICC:0.91-0.99; SDC:6-10; Bland-Altman plots were homoscedastic, with negligible systematic error between readers. Readers agreed on the direction of change in 88-96% and on change >|SDC| in 58-94% of vertebrae, per vertebral level, from C3 to L5. Overall, similar results were obtained across all vertebrae.

LdCT measurement of HU is a reliable method to assess two-year changes in trabecular bone density at each vertebra from C3-L5. Being reliable across all vertebrae, this methodology can aid the study of trabecular bone density changes over time in r-axSpA, a disease affecting the whole spine.