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Introduction: Adequate bone quality is essential for long term biologic fixation of cementless total knee arthroplasty (TKA). Recently, vertebral bone quality evaluation using dual-energy computed tomography (DECT) has been introduced. However, the DECT bone mineral density (BMD) in peripheral skeleton has not been correlated with Hounsfield units (HU) or central dual-energy X-ray absorptiometry (DXA), and the accuracy remains unclear. Materials and methods: Medical records of 117 patients who underwent TKA were reviewed. DXA was completed within three months before surgery. DECT was performed with third-generation dual source CT in dual-energy mode. Correlations between DXA, DECT BMD and HU for central and periarticular regions were analyzed. Receiver operating characteristic (ROC) curves were plotted and area under the curve (AUC), optimal threshold, and sensitivity and specificity of each region of interest (ROI) were calculated. Results: Central DXA BMD was correlated with DECT BMD and HU in ROIs both centrally and around the knee (all p < 0.01). The diagnostic accuracy of DECT BMD was higher than that of DECT HU and was also higher when the T-score for second lumbar vertebra (L2), rather than for the femur neck, was used as the reference standard (all AUC values: L2 > femur neck; DECT BMD > DECT HU, respectively). Using the DXA T-score at L2 as the reference standard, the optimal DECT BMD cut-off values for osteoporosis were 89.2 mg/cm3 in the distal femur and 78.3 mg/cm3 in the proximal tibia. Conclusion: Opportunistic volumetric BMD assessment using DECT is accurate and relatively simple, and does not require extra equipment. DECT BMD and HU are useful for osteoporosis screening before cementless TKA.

Objective Osteoporosis is a crucial risk factor for screw loosening. Our studies indicate that the bone mineral density (BMD) in the screw trajectory is a better predictor of screw loosening than the BMD of the lumbar spine or the screw insertion position. Research has shown that anchorage on the screw tip is the most significant factor for screw anchorage ability, while others argue that decreased bony quality in the pedicle poses a significant risk for screw loosening. This study aimed to determine whether the bony quality of the screw tip, pedicle, or screw‐anchored vertebral body plays the most significant role in screw anchorage ability. Methods A total of 73 patients who underwent single–segment bilateral pedicle screw fixation, along with posterior and transforaminal lumbar interbody fusion (PLIF and TLIF), from March 2019 to September 2020 were included in this retrospective study. The Hounsfield unit (HU) value of the fixed vertebral bodies, the entire screw trajectory, screw tip, screw–anchoraged vertebral body, and pedicles were measured separately. Data from patients with and without screw loosening were compared, and regression analyses were conducted to identify independent risk factors. Additionally, the area under the curve (AUC) values were computed to assess the predictive performance of different parameters. Furthermore, fixation strength was calculated in numerical models with varying bony densities in different regions. Results HU values were found to be significantly lower in the loosening group across most measuring methods (HU values in the pedicle, 148.79 ± 97.04, 33.06 ± 34.82, p < 0.001). Specifically, the AUC of screw loosening prediction was notably higher when using HU values of the pedicle compared to other methods (AUC in the pedicle > 0.9 and in the screw insertion position > 0.7). Additionally, computational results for fixation strength revealed a clear decline in screw anchorage ability in models with poor BMD in the pedicle region. Conclusions Pedicle bone quality plays a more significant role in screw anchorage ability than that in other regions. The innovation of bony augmentation strategies should pay more attention to this region to optimize the screw anchorage ability effectively. Pedicle bony density predicts risk of pedicle screw loosening.

Based on mean Hounsfield Unit (HuMean), we aimed to evaluate the additional use of standard deviation of Hounsfield Unit (HuStd), minimum Hounsfield Unit (HuMin), and maximum Hounsfield Unit (HuMax) in noncontrast computed tomography (NCCT) to evaluate uric acid (UA) stones more accurately. The data of patients who underwent the NCCT examination and infrared spectroscopy in our hospital from August 2017 to December 2021 were analyzed retrospectively. Based on CT scans, the HuMean, HuStd, HuMin, and HuMax of all patients were measured. The patients were divided into groups according to the stone composition. The attenuation value of mixed stones was in the middle of their pure stones. Except for Str, statistically significant differences between UA stones and other pure stones were observed for HuMean, HuStd, HuMin, and HuMax. A moderate correlation was found between HuMean, HuStd, HuMin, and HuMax and UA stones (rs showed −0.585, −0.409, −0.492, and −0.577, respectively). Receiver operator characteristic (ROC) curve showed that the area under the curve (AUC) of HuMean and HuMax were higher than those of HuStd and HuMin (AUC = 0.896, AUC = 0.891 vs. AUC = 0.777, AUC = 0.833). Higher AUC (0.904), specificity (0.899) and positive predictive value (PPV) (0.712) can be obtained by combining HuMean and HuMax in the diagnosis of UA stones. In conclusion, HuMean and HuMax can better predict UA stones than HuStd and HuMin. The combined use of HuMean and HuMax can lead to higher accuracy.

Purpose This study evaluates the dosimetric accuracy of three image‐guided radiotherapy (IGRT) imaging modalities, cone‐beam computed tomography (CBCT), megavoltage computed tomography (MVCT), and image‐guided kilovoltage computed tomography (IG‐kVCT), using modality‐specific HU‐to‐density (HU‐D) calibrations. Dose calculations from IGRT images were compared to computed tomography simulation (CT‐sim) references in phantoms and validated against measurements from head and neck and prostate patient plans to assess the feasibility of each modality for precise dose calculation in adaptive radiotherapy (ART). Methods Two phantoms, the Tomo phantom HE and CIRS Thorax phantom, were used for HU‐to‐density (HU‐D) calibration. IGRT images were acquired using Elekta Synergy XVI (CBCT) and Radixact X9 (MVCT and IG‐kVCT), and calibration curves were generated for each modality. Dose distributions calculated from IGRT images were then compared with those from CT‐sim in phantom studies. For measurement‐based evaluation, 10 patient plans (head and neck and prostate cases) were delivered to a phantom and measured using the ArcCHECK system, and recalculated doses on CT‐sim and IGRT images were compared to the measured doses. Gamma analysis was performed to assess dosimetric accuracy. Results IG‐kVCT showed the closest agreement with CT‐sim, achieving gamma passing rates (GPR) of 99.8% ± 0.3% for 3%/3 mm and 98.5% ± 0.7% for 3%/2 mm criteria, with dose differences below 1%. CBCT and MVCT demonstrated slightly lower accuracy, with GPRs of 97.2% ± 1.1% and 96.5% ± 1.3% for 3%/3 mm, respectively, and dose differences up to 2%. Similar trends were observed when compared to measured doses. All IGRT modalities showed clinically acceptable agreement, and no statistically significant differences were found between CT‐sim and any IGRT modality. Conclusion All three IGRT modalities demonstrated clinically acceptable accuracy for adaptive dose calculation with modality‐specific HU‐D calibration curves.

Background and Objectives: In this retrospective cohort study, we investigate associations between the Hounsfield units (HU) value of upper instrumented vertebra (UIV) and proximal junctional kyphosis (PJK) after adult spinal deformity (ASD) surgery. Materials and Methods: The cohort consisted of 60 patients (mean age 71.7 years) who underwent long instrumented fusion surgery (≥6 vertebrae) for ASD with at least 1 year of follow-up. The preoperative bone mineral density (BMD) measured on DXA scans, the HU values at UIV and UIV+1, and the radiographic parameters were compared between the PJK and non-PJK groups. The severity of UIV fracture was assessed using a semiquantitative (SQ) grade. Results: PJK occurred in 43% of patients. No significant differences in patient age, sex, BMD, and preoperative radiographic parameters were observed between the PJK and non-PJK groups. The HU values of the UIV (103.4 vs. 149.0, p < 0.001) and UIV+1 (102.0 vs. 145.7, p < 0.001) were significantly lower in the PJK group. The cutoff values of HU at UIV and UIV+1 were 122.8 and 114.9, respectively. Lower HU values at UIV (Grade 1: 134.2, Grade 2: 109.6, Grade 3: 81.1, p < 0.001) and UIV+1 (Grade 1: 131.5, Grade 2: 107.1, Grade 3: 82.1, p < 0.001) were associated with severe SQ grade. Conclusions: Lower HU values at UIV and UIV+1 had a negative impact on signal incidence of PJK and were correlated with the severity of UIV fractures. Preoperative treatment of osteoporosis seems necessary for preoperative UIV HU values less than 120.

Objective: To assess jawbone density in terms of Hounsfield units using cone beam computed tomography fordental implant treatment planning in patients reporting to a local tertiary care dental hospital Study Design: Cross sectional study. Place and Duration of Study: Department of Periodontology and Oral Implantology, Fatima Memorial Hospital, Lahore, from Mar to Sep 2018. Methodology: A total of 100 patients who fulfilled the inclusion criteria and underwent implant placement wereincluded in the study. After ethical approval, informed and written consent, brief history was taken and a singleradiographer exposed and took cone beam computed tomography scan of all the subjects using PLANMECAmachine. A single investigator using PLANMECA software recorded jawbone density in terms of Hounsfieldunits. All data were presented as mean, SD and one way ANOVA was used. Multiple comparisons of the fourregions in the maxilla and mandible were performed with a Tukey test. An independent t-test was also used tocompare gender with age groups and bone density. Results: Total of 100 patients who underwent implant placement were included, 48 (48%) were males & 52 (52%) were females with the mean age of 28.53 ± 5.33 years. The mean jawbone density in terms of Hounsfield units using cone beam computed tomography in anterior maxilla was 709.75 ± 122.63 Hounsfield units, posterior maxilla was 299.66 ± 73.09 Hounsfield units, anterior mandible was 1093.34 ± 109.42 Hounsfield units and posterior mandible was 599.45 ± 135.55 Hounsfield units (p<.001). Conclusion: The anterior mandible and anterior...

PurposeThe purpose of the study was to investigate the predictive value of stone measurements by including a novel method on non-contrast computed tomography (NCCT) images for stone composition.MethodsWe retrospectively evaluated patients who had stone analysis, NCCT images, and underwent percutaneous nephrolithotomy between 2013 and 2016. Patient characteristics, stone measurements on NCCT images, and stone analysis results were evaluated. Hounsfield unit (HU) values (maximum (HUmax), minimum (HUmin), and average (HUave) of HU values) were investigated on NCCT images. HUdiff was calculated as the difference between the HUmax and the HUmin values. Patients were divided into seven stone groups and data were compared. Then patients were separately divided into two groups according to mineral complexity (mono-mineral and multi-mineral groups) and calcium-based (calcium and other stone groups) evaluation.ResultsIn the study, 115 patients were evaluated. Age, gender, HUmin, HUmax, and HUave were significantly different between the stone groups. HUdiff and HUave were found to be 341.5 HU (AUC = 0.719, p = 0.017) and 1051.5 HU (AUC = 0.701, p = 0.029) as cut-off, respectively. Seventy of 72 > 341.5 HUdiff patients and 64 of 67 > 1051.5 HUave patients had multi-mineral stones (p = 0.001, OR 9.26, and p = 0.028, OR 4.27), respectively. In multivariate analysis, > 341.5 HUdiff rate was significantly higher in multi-mineral and calcium stone groups; HUave was also significantly higher in the calcium stone group.ConclusionsHUdiff and HUave were significant predictors of mineral complexity. HUdiff of < 341.5 HU showed 81.8% sensitivity and 67.2% specificity for identification of mono-mineral stones.

PurposesOur purpose was to use computed tomography (CT) Hounsfield unit (HU) values to identify the undiagnosed spinal osteoporosis in patients with lumbar degenerative diseases.MethodsA total of 334 patients with lumbar degenerative diseases were retrospectively reviewed and divided into two groups according to the degree of lumbar degenerative changes in preoperative lumbar CT images. Patients who had at least three vertebrae with severe degeneration at L1–L4 were placed in the degenerative group, and others were placed in the control group. HU value of trabecular bone in middle axial CT image of vertebral body, T-score and bone mineral density (BMD) at L1–L4 and hips were measured. CT HU thresholds for osteoporosis were obtained from control group and then applied to identify undiagnosed spinal osteoporosis.ResultsThere were 182 patients in the degenerative group and 152 patients in the control group. CT HU value had a positive correlation with T-score and BMD of lumbar spine in both groups (P < 0.001), while the correlation coefficients at L1–L4 were higher in the control group (> 0.7) than in the degenerative group (< 0.7). T-score and BMD of lumbar spine were higher in the degenerative group (P < 0.05), while CT HU value, T-score and BMD of hips had no significant difference between two groups. According to the linear regression equations of vertebral T-score and CT HU value in the control group, the thresholds matching T-score of − 2.5 were 110, 100, 85 and 80HU for L1, L2, L3 and L4, respectively. Defining CT osteoporosis as L1 ≤ 110HU or L2 ≤ 100HU or L3 ≤ 85HU or L4 ≤ 80HU was 88.5% (69/78) specific and 60.8% (45/74) sensitive for distinguishing DXA osteoporosis of lumbar spine in the control group. The rate of undiagnosed spinal osteoporosis was higher in the degenerative group than in the control group according to CT HU thresholds (38.7% vs. 11.5%, P < 0.05).ConclusionsDegenerative changes in the lumbar spine can increase BMD and T-score provided by lumbar DXA, leading to an underestimation of vertebral osteoporosis. Thresholds for osteoporosis based on CT HU values can be used as a complementary method to identify undiagnosed spinal osteoporosis in patients with lumbar degenerative diseases.Graphical abstractThese slides can be retrieved under Electronic Supplementary Material.

Abstract Adrenal tumors are commonly discovered incidentally on cross-sectional abdominal imaging performed for reasons other than adrenal mass. Incidence of adrenal tumors increased 10-fold in the past 2 decades, with most diagnosed in older adults. In any patient with a newly discovered adrenal mass, determining whether the adrenal mass is malignant and whether it is hormonally active is equally important to guide the best management. Malignancy is diagnosed in 5% to 8% of patients with adrenal tumors, with a higher risk in young patients, if history of extra-adrenal malignancy, in those with large adrenal tumors with indeterminate imaging characteristics, and in bilateral adrenal tumors. Although overt hormone excess is uncommon in adrenal incidentalomas, mild autonomous cortisol secretion can be diagnosed in up to 30% to 50% of patients. Because autonomous cortisol secretion is associated with increased cardiovascular morbidity and metabolic abnormalities, all patients with adrenal incidentalomas require work up with dexamethasone suppression test. Management of adrenal tumors varies based on etiology, associated comorbidities, and patient’s preference. This article reviews the current evidence on the diagnosis and evaluation of patients with adrenal mass and focuses on management of the most common etiologies of adrenal incidentalomas.

Objective: The objective was to determine the predicting success of shock wave lithotripsy (SWL) using a combination of computed tomography based metric parameters to improve the treatment plan. Patients and Methods: Consecutive 180 patients with symptomatic upper urinary tract calculi 20 mm or less were enrolled in our study underwent extracorporeal SWL were divided into two main groups, according to the stone size, Group A (92 patients with stone ≤10 mm) and Group B (88 patients with stone >10 mm). Both groups were evaluated, according to the skin to stone distance (SSD) and Hounsfield units (≤500, 500-1000 and >1000 HU). Results: Both groups were comparable in baseline data and stone characteristics. About 92.3% of Group A rendered stone-free, whereas 77.2% were stone-free in Group B (P = 0.001). Furthermore, in both group SWL success rates was a significantly higher for stones with lower attenuation <830 HU than with stones >830 HU (P < 0.034). SSD were statistically differences in SWL outcome (P < 0.02). Simultaneous consideration of three parameters stone size, stone attenuation value, and SSD; we found that stone-free rate (SFR) was 100% for stone attenuation value <830 HU for stone <10 mm or >10 mm but total number SWL sessions and shock waves required for the larger stone group were higher than in the smaller group (P < 0.01). Furthermore, SFR was 83.3% and 37.5% for stone <10 mm, mean HU >830, SSD 90 mm and SSD >120 mm, respectively. On the other hand, SFR was 52.6% and 28.57% for stone >10 mm, mean HU >830, SSD <90 mm and SSD >120 mm, respectively. Conclusion: Stone size, stone density (HU), and SSD is simple to calculate and can be reported by radiologists to applying combined score help to augment predictive power of SWL, reduce cost, and improving of treatment strategies.