OBJECTIVE: This study investigated the correlation between Hounsfield units (HU) of the cervical vertebrae and atrophy of the cervical deep paraspinal muscles, namely the multifidus and semispinalis cervicis (SCer), in patients diagnosed with degenerative cervical myelopathy (DCM).
METHODS: The authors retrospectively analyzed data from 136 patients aged 50-79 years (81 males and 55 females) who underwent surgical intervention for DCM. HU measurements of the cancellous bone in the C4 vertebra were acquired through standardized techniques. The authors evaluated fatty infiltration (FI); analyzed functional and vertebral cross-sectional area (CSA) of the multifidus and SCer at the C4-5, C5-6, and C6-7 levels; and analyzed the presence of Modic changes (MCs) and the incidence of axial neck pain.
RESULTS: Patients were categorized into group A (n = 56) with mean ± SD HU of 293.3 ± 15.6 and group B (n = 80) with mean ± SD HU of 389.5 ± 10.6. Both groups demonstrated significant improvements in postoperative clinical outcomes (p < 0.05); however, no statistically significant difference was observed (p > 0.05). Significant disparities in HU measurements and visual analog scale (VAS) scores for neck pain were observed between the groups (p < 0.05). The highest VAS score correlated with MCs-1 type (i.e., low signal on T1-weighted images and high signal on T2-weighted images). The functional CSA to vertebral CSA ratios of the multifidus and SCer in group A were markedly reduced compared to those of group B (p < 0.05). No significant difference was noted in functional CSA asymmetry between the groups for both muscles (p > 0.05). Lower HU measurements directly correlated with increased FI in the multifidus (p = 0.002) and SCer (p = 0.035). Furthermore, a strong positive association was found between the functional CSA to vertebral CSA ratio of the multifidus and HU values (p = 0.003), whereas HU measurements and VAS scores exhibited a negative correlation (p = 0.020).
CONCLUSIONS: Among those patients older than 50 years with DCM, those with decreased HU values demonstrated elevated FI levels in the multifidus and SCer muscles. Moreover, these patients presented with pronounced muscle atrophy, which correlated with axial neck pain. A significant relationship was also identified between MCs and diminished HU values.

Pleural effusion is a common medical problem. It is important to decide whether the pleural fluid is a transudate or an exudate. This study aims to measure the attenuation values of pleural effusions on thorax computed tomography and to investigate the efficacy of this measurement in the diagnostic separation of transudates and exudates.
380 cases who underwent thoracentesis and thorax computed tomography with pleural effusion were classified as exudates or transudates based on Light\'s criteria. Attenuation measurements in Hounsfield units were performed through the examination of thorax computed tomography images.
380 patients were enrolled (39 % women), the mean age was 69.9 ± 15.2 years. 125 (33 %) were transudates whereas 255 (67 %) were exudates. The attenuation values of exudates were significantly higher than transudates (15.1 ± 5.1 and 5.0 ± 3.4) (p < 0.001). When the attenuation cut-off was set at ≥ 10 HU, exudates were differentiated from transudates at high efficiency (sensitivity is 89.7 %, specificity is 94.4 %, PPV is 97 %, NPV is 81.9 %). When the cut-off value was accepted as < 6 HU, transudates were differentiated from exudates with 97.2 % specificity.
The attenuation measurements of pleural fluids can be considered as an efficacious way of differentiating exudative and transudative pleural effusions.

METHODS: Retrospective cohort study.
OBJECTIVE: The impact of paraspinal sarcopenia following fusions that extend to the upper thoracic spine remain unknown. The purpose of the present study was to assess the impact of sarcopenia on the development of PJK and PJF following spine fusion surgery from the upper thoracic spine to the pelvis.
METHODS: We performed a retrospective review of patients who underwent spine fusion surgery that extended caudally to the pelvis and terminated cranially between T1-6. The cohort was divided into 2 groups: (1) patients without PJK or PJF and (2) patients with PJK and/or PJF. Univariate and multivariate analyses were performed to determine risk factors for the development of proximal junctional complications.
RESULTS: We identified 81 patients for inclusion in this study. Mean HU at the UIV was 186.1 ± 47.5 in the cohort of patients without PJK or PJF, which was substantially higher than values recorded in the PJK/PJF subgroup (142.4 ± 40.2) (P < 0.001). Severe multifidus sarcopenia was identified at a higher rate in the subgroup of patients who developed proximal junction pathology (66.7%) than in the subgroup of patients who developed neither PJK nor PJF (7.4%; P < 0.001). Multivariate analysis demonstrated both low HU at the UIV and moderate-severe multifidus sarcopenia to be risk factors for the development of PJK and PJF.
CONCLUSIONS: Severe paraspinal sarcopenia and diminished bone density at the UIV impart an increased risk of developing PJK and PJF in following thoracolumbar fusions from the upper thoracic spine to the pelvis.

OBJECTIVE: To perform a quantitative analysis of the amount of cancellous bone in the distal radius and olecranon process by segmentation of computed tomographic scans. As a secondary analysis, the bone density by Hounsfield units was evaluated at the same sites.
METHODS: Computed tomography angiography images of the upper extremity were analyzed using 3-D Slicer™ medical imaging software. Bone volume (cm3) and density (Hounsfield units) from the cancellous bone between the distal radius and the olecranon process were compared by creating an advanced three-dimensional model. The images were analyzed in duplicate, and an intraclass correlation was performed to assess measurement consistency.
RESULTS: Twenty subjects were included. A total volume of 5.01 ± 1.21 cm3 and 5.81 ± 1.61 cm3 for the distal radius and the olecranon process (p < .0001), respectively, was found. Regarding Hounsfield units, the density of the olecranon process was 303.1 ± 73.26, and the distal radius was 206.5 ± 63.73 (p < .0001). All intraclass correlation coefficients were >0.992.
CONCLUSIONS: These results suggest that the olecranon process has a greater volume and a higher bone mineral density than the distal radius. With these results, the surgeon will have the ability to decide the quantity and quality of bone grafts according to the surgical procedure.

Introduction The canal-to-calcar isthmus (CC) ratio has been previously correlated with proximal femur osteology, but its relationship with bone density is not well established. Our purpose was to assess the relationship between femoral bone density, measured on opportunistic quantitative CT in Hounsfield units (HU), and CC ratio. Methods A total of 148 THA patients were included. The CC ratio was measured on anteroposterior hip radiographs. Using perioperative CT scans, a 1 cm diameter area was identified on a single mid-coronal slice in the medial calcar just proximal to the intertrochanteric ridge. The mean HU was calculated in this region to represent calcar bone density. Results Twenty-four percent (n = 35) of patients were classified as Dorr A (average CC ratio 0.47 [0.45; 0.48]), 67% (n = 96) as Dorr B (0.62 [0.55; 0.68]), and 11% (n = 17) as Dorr C (0.78 [0.77; 0.80]). There was a significant difference between Dorr A and Dorr C femurs (769 (144) vs. 588 (154) HU) as well as between B and C femurs (718 (166) vs. 588 (154) HU). The CC ratio was correlated with calcar bone density on CT (-0.370). Conclusion CC ratio is correlated with bone density determined by HU measurements on an opportunistic quantitative computed tomography scan, and bone density HU values were able to accurately differentiate bone density in Dorr A and B from Dorr C femurs. These findings suggest that the CC ratio is a reliable measurement to predict bone density in Dorr C femurs. Therefore, arthroplasty surgeons can confidently use the Dorr classification for patients with Dorr C femurs when preoperatively planning for THA.

OBJECTIVE: The purpose of this study was to determine the effect of osteoporosis medications on opportunistic CT-based Hounsfield units (HU).
METHODS: Spine and nonspine surgery patients were retrospectively identified who had been treated with romosozumab for 3 to 12 months, teriparatide for 3 to 12 months, teriparatide for > 12 months, denosumab for > 12 months, or alendronate for > 12 months. HU were measured in the L1-4 vertebral bodies. One-way ANOVA was used to compare the mean change in HU among the five treatment regimens.
RESULTS: In total, 318 patients (70% women) were included, with a mean age of 69 years and mean BMI of 27 kg/m2. There was a significant difference in mean HU improvement (p < 0.001) following treatment with romosozumab for 3 to 12 months (n = 32), teriparatide for 3 to 12 months (n = 30), teriparatide for > 12 months (n = 44), denosumab for > 12 months (n = 123), and alendronate for > 12 months (n = 100). Treatment with romosozumab for a mean of 10.5 months significantly increased the mean HU by 26%, from a baseline of 85 to 107 (p = 0.012). Patients treated with teriparatide for > 12 months (mean 23 months) experienced a mean HU improvement of 25%, from 106 to 132 (p = 0.039). Compared with the mean baseline HU, there was no significant difference after treatment with teriparatide for 3 to 12 months (110 to 119, p = 0.48), denosumab for > 12 months (105 to 107, p = 0.68), or alendronate for > 12 months (111 to 113, p = 0.80).
CONCLUSIONS: Patients treated with romosozumab for a mean of 10.5 months and teriparatide for a mean of 23 months experienced improved spinal bone mineral density as estimated by CT-based opportunistic HU. Given the shorter duration of effective treatment, romosozumab may be the preferred medication for optimization of osteoporotic patients in preparation for elective spine fusion surgery.

UNASSIGNED: Adults undergoing spine surgery often have underlying osteoporosis, which may be a risk factor for postoperative complications. Although these associations have been described, osteoporosis remains profoundly underdiagnosed and undertreated in the spine surgery population. A thorough, comprehensive systematic review summarizing the relationships between bone mineral density (BMD) and specific complications of lumbar fusion surgery could be a valuable resource for raising awareness and supporting clinical practice changes.
UNASSIGNED: PubMed, Embase, and Web of Science databases were searched for original clinical research articles reporting on BMD, or surrogate measure, as a predictor of complications in adults undergoing elective lumbar fusion for degenerative disease or deformity. Endpoints included cage subsidence, screw loosening, pseudarthrosis, vertebral fracture, junctional complications, and reoperation.
UNASSIGNED: A total of 71 studies comprising 12,278 patients were included. Overall, considerable heterogeneity in study populations, methods of bone health assessment, and definition and evaluation of clinical endpoints precluded meta-analysis. Nevertheless, low BMD was associated with higher rates of implant failures like cage subsidence and screw loosening, which were often diagnosed with concomitant pseudarthrosis. Osteoporosis was also a significant risk factor for proximal junctional kyphosis, particularly due to fracture. Many studies found surgical site-specific BMD to best predict focal complications. Functional outcomes were inconsistently addressed.
UNASSIGNED: Our findings suggest osteoporosis is a significant risk factor for mechanical complications of lumbar fusion. These results emphasize the importance of preoperative osteoporosis screening, which allows for medical and surgical optimization of high-risk patients. This review also highlights current practical challenges facing bone health evaluation in patients undergoing elective surgery. Future prospective studies using standardized methods are necessary to strengthen existing evidence, identify optimal predictive thresholds, and establish specialty-specific practice guidelines. In the meantime, an awareness of the surgical implications of osteoporosis and utility of preoperative screening can provide for more informed, effective patient care.

(1) Background: it is challenging to determine the accurate grades of cartilaginous bone tumors. Using bone single photon emission computed tomography (SPECT)/computed tomography (CT), maximum standardized uptake value (SUVmax) was found to be significantly associated with different grades of cartilaginous bone tumor. The inquiry focused on the effect of the tumor matrix on SUVmax. (2) Methods: a total of 65 patients from 2017 to 2022 with central cartilaginous bone tumors, including enchondromas and low-to-intermediate grade chondrosarcomas, who had undergone bone SPECT/CT were retrospectively enrolled. The SUVmax was recorded and any aggressive CT findings of cartilaginous bone tumor and Hounsfield units (HU) of the chondroid matrix as mean, minimum, maximum, and standard deviation (SD) were reviewed on CT scans. Pearson\'s correlation analysis was performed to determine the relationship between CT features and SUVmax. Subgroup analysis was also performed between the benign group (enchondroma) and the malignant group (grade 1 and 2 chondrosarcoma) for comparison of HU values and SUVmax. (3) Results: a significant negative correlation between SUVmax and HU measurements, including HUmax, HUmean, and HUSD, was found. The subgroup analysis showed significantly higher SUVmax in the malignant group, with more frequent CT aggressive features, and significantly lower HUSD in the malignant group than in the benign group. (4) Conclusions: it was observed that higher SUVmax and lower HUSD were associated with a higher probability of having a low-to-intermediate chondrosarcoma with aggressive features and a less calcified tumor matrix.

METHODS: Retrospective cohort study.
OBJECTIVE: In general, Multiple Myeloma (MM) patients are treated with systemic therapy including chemotherapy. Radiation therapy can have an important supportive role in the palliative management of MM-related osteolytic lesions. Our study aims to investigate the degree of radiation-induced remineralization in MM patients to gain a better understanding of its potential impact on bone mineral density and, consequently, fracture prevention. Our primary outcome measure was percent change in bone mineral density measured in Hounsfield Units (Δ% HU) between pre- and post-radiation measurements, compared to non-targeted vertebrae.
METHODS: We included 119 patients with MM who underwent radiotherapy of the spine between January 2010 and June 2021 and who had a CT scan of the spine at baseline and between 3-24 months after radiation. A linear mixed effect model tested any differences in remineralization rate per month (βdifference) between targeted and non-targeted vertebrae.
RESULTS: Analyses of CT scans yielded 565 unique vertebrae (366 targeted and 199 non-targeted vertebrae). In both targeted and non-targeted vertebrae, there was an increase in bone density per month (βoverall = .04; P = .002) with the largest effect being between 9-18 months post-radiation. Radiation did not cause a greater increase in bone density per month compared to non-targeted vertebrae (βdifference = .67; P = .118).
CONCLUSIONS: Our results demonstrate that following radiation, bone density increased over time for both targeted and non-targeted vertebrae. However, no conclusive evidence was found that targeted vertebrae have a higher remineralization rate than non-targeted vertebrae in patients with MM.

BACKGROUND: Sarcopenia is a progressively diminishing state characterized by the reduction of muscle mass and density, which is frequently observed in malignancies of solid organs.
OBJECTIVE: To assess how sarcopenia affects the overall survival of individuals who have been diagnosed with metastatic gastric cancer.
METHODS: The study retrospectively included individuals who had been diagnosed with metastatic gastric cancer between January 2008 and December 2020. Sarcopenia was identified through the calculation of the average Hounsfield units (HUAC) using computed tomography (CT) images taken at the time of diagnosis in patients.
RESULTS: A total of 118 patients with metastatic gastric cancer were evaluated. Sarcopenia was detected in 29 patients (24.6%). The median survival of all patients was 8 (1-43) mo. The median survival of patients with sarcopenia was 2 mo, while it was 10 mo for those without sarcopenia (P < 0.001). A significant relationship was found between sarcopenia and survival.
CONCLUSIONS: Sarcopenia has been observed to impact survival outcomes in various types of solid tumor cancers. Sarcopenic patients can be identified in a short time, easily and inexpensively, by HUAC measurements from CT images used for diagnosis, and survival could be promoted with nutritional support.