The Relationship Between Arachnoid Cysts and the Subarachnoid Space by Hounsfield Unit Value in Computed Tomography Scans: Identification of Isolated and Communicating Arachnoid Cysts in a Cohort Study

PurposeThe difference of Hounsfield Unit (HU) value in different regions of L3 vertebra in middle-aged and elderly patients with lumbar degeneration diseases (LDD) was analyzed. To investigate the influence of proliferative tissue on HU value of cancellous bone and its correlation with bone mineral density (BMD).MethodsThe medical records of middle-aged and elderly patients with LDD in our hospital from December 2020 to December 2023 were retrospectively analyzed. The patients were divided into osteophyte group and no-osteophyte group according to the presence or absence of osteophyte formation on lumbar spine X-ray. In osteophyte group, cancellous bone HU value, containing cortical bone overall HU value and containing osteophyte overall HU value in L3 vertebra were measured on the lumbar CT cross-section. In no-osteophyte group, only the cancellous bone HU value and the containing cortical bone overall HU value were measured. Differences in HU value in different regions of the L3 vertebral body were compared within and between groups of middle-aged and elderly patients with LDD, respectively. To investigate its effect on cancellous bone HU measurements and to do a correlation analysis with patients’ BMD.ResultsA total of 115 patients with LDD were included in this study, including 65 males and 50 females, with an average age of 67.83 ± 6.59 years. The results of the study showed no statistical differences in age (P = 0.15), gender (P = 0.57), smoking (P = 0.88), drinking history (P = 0.76), medical history (P > 0.05) and BMI(P = 0.29) between the two groups. In osteophyte group, the mean cancellous bone HU value was 98.00 ± 25.50 HU, the containing cortical bone overall HU value was 189.02 ± 46.18 HU, and the containing osteophyte overall HU value was 232.69 ± 56.01 HU. The overall HU values containing cortical bone and containing osteophyte were significantly higher than cancellous bone HU value (P < 0.001). In no-osteophyte group, the mean cancellous bone HU value was 102.04 ± 19.64 HU, and the containing cortical bone overall HU value was 175.00 ± 28.97 HU, which was statistically significantly different (P < 0.001). There was no significant difference in cancellous bone HU value and the containing cortical bone overall HU value between the two groups (P > 0.05). The results of the Pearson correlation analysis showed a significant correlation between the cancellous bone HU value of the L3 vertebrae and the QCT BMD value of the patients (r = 0.95, P < 0.001). However, there was no significant correlation between containing cortical bone overall HU value and containing osteophyte overall HU value and the patient’s QCT BMD value (P > 0.05).ConclusionsVertebral HU value is an alternative measurement that effectively reflects the patient’s BMD. In middle-aged and elderly LDD patients, HU values in different areas of L3 vertebra are significantly different, and hyperplastic tissues such as cortical bone and osteophytes may exponentially lead to higher HU value in patients. Compared with other measurement areas, vertebral cancellous bone HU value have the advantage of accurately assessing patients’ BMD.

Computed Tomography (CT) produces excellent images when diagnosing patient abnormalities. However, the dose received by some radiation-sensitive organs is a significant concern. This study aims to evaluate the reduction in Hounsfield Unit (HU) values and the resulting image quality of a composite-based shielding consisting of silicon rubber (SR) and lead (Pb), comparing it to whole-body chicken images without shielding during CT examination of the abdomen. Exposure factor by type of abdominal protocols with a voltage of 70 kV, 19 mAs, CTDIvol 0.35 mGy, and DLP 18.8 mGy.cm.The synthetic SR-Pb shield had Pb percentages ranging from 0 to 5 wt% and a thickness of 0.6 cm. Scanning on the chicken's abdomen was performed with and without the SR-Pb shield placed directly on the abdomen surface. The HU values were analyzed using MicroDicom software. Image quality was assessed based on the consistency of HU values in the object's anterior, posterior, and lateral areas. A detailed evaluation of image quality was conducted using image subtraction techniques. The study found that the HU values for specific organs did not tend to increase significantly with an increase in the Pb percentage in the SR-Pb shield. The use of the SR-Pb shield had a minor impact on the resulting images, and image quality was well-maintained for every anatomical part. Application of SR in CT examination with precise image results and HU value of each white matter 79-93 HU, liver 86-111 HU, ribs 1032-1189 HU, wing bones 391-531 HU, upper femur 1512 – 1746 HU. In conclusion, the study demonstrates that the resulting images are high quality without artifacts in chicken images, even at higher Pb percentages. Keywords: shielding, silicon rubber, CT Examination.

Background and purpose: Cerebral infarction is a severe medical condition that requires accurate diagnosis and management and can be achieved with the used of computed tomography (CT). Hounsfield unit (HU) values measured on CT scans may provide essential information concerning the severity of cerebral infarction. This study investigated the association between the HU values and the severity (phase) of cerebral infarction. Methods: A descriptive cross-sectional design was used to gather data from 102 patients over seven months (August 2023 to February 2024) at the University of Lahore Teaching Hospital after the study had been ethically approved by an institutional review board. HU measurements were made with standardized CT protocol on a 4-slice Toshiba equipment. Data were analyzed descriptively and inferentially to reveal the association between HU measurements and the severity of cerebral infarction (acute, sub-acute, and chronic phases). The inferential statistics included Bayesian ANOVA and one-way ANOVA, assuming significance at p≤0.05. Results: The study found a significant association between the HU values and the severity of cerebral infarction (p&lt;0.000), with the acute phase exhibiting higher mean values (HU=22.31), while the sub-acute and chronic phases followed with HU values of 14.63 and 7.04 respectively. There was a progressive decrease in HU values from the acute phase (HU range = 19 to 25) to the chronic phase (HU values &lt;10). Conclusion: This study identified a significant relationship between the CT phases and the HU values in cerebral infarction. The results show the clinical significance of HU values in potentially diagnosing and managing cerebral infarction. An understanding of the association between the HU measurements and CT phase may be useful in accurately evaluating cerebral infarctions and subsequently make informed decisions regarding patient management and treatment. The results also underscore the importance and potential of HU values in evaluating cerebral infarctions, providing a roadmap for improving patient outcomes in the diagnosis of cerebral infarctions with CT.

Rationale and objectiveOsteoporosis, a common non-pathological disease of bones, has been the cause of many disastrous consequences, in terms of physical, psychological, social, and economic loss. Therefore, it is crucial to diagnose it early for timely prevention and treatment of osteoporotic fractures. Dual-Energy X-Ray Absorptiometry (DEXA) is currently routinely used for determining bone mineral density. However, it has its limitations. Nowadays, CT technology has advanced so rapidly that the Hounsfield units (HU) values can be used in opportunistic screening for osteoporosis in patients during routine CT abdomen for other causes. Hence, there would be no need for additional study with DEXA and also reduce radiation exposure. The aim of our research is to determine whether there is a correlation between the bone mineral density and the T-score measured by DEXA and the HU values measured from the diagnostic CT images of L1-4 vertebrae. Also, to determine reference CT values that would help in screening the patients with osteoporosis.Materials and methodsWe conducted a retrospective study of 78 female patients who underwent CT lumbar spine, abdomen, and pelvis in our hospital between the years 2016-2020. We collected data of patients who performed DEXA and CT scans within an interval of up to two years. The final collected data was analyzed to find correlation values of HU with age group and with DEXA bone mineral density (BMD) and T-score using Pearson correlation coefficient.ResultsThe mean of the 78 patients was 61.1 (range 37-88 years). Mean HU values decreased consistently with age, from 202.17 HU in the fifth decade to 71 HU in the ninth decade. Average L1-4 HU values ranged from 71 HU to 202.17 HU (mean with standard deviation), while their T-score ranged from -4.4 to +2.4 (mean was -1.7±1.41), and their BMD ranged from 0.62 to 1.465 g/cm2 (mean, 0.974±0.175 g/cm2). For each lumbar vertebra, the correlations of HU values with bone mineral density and T-score were calculated separately. For L1-4 vertebrae, the correlation coefficients (r2) for the HU value and T-score were 0.544, 0.600, 0.611, and 0.600, respectively. The correlation coefficients (r2) for the HU value and bone mineral density were 0.581, 0.623, 0.653,0.612, respectively. All the calculated correlations were significant (p<0.001). Therefore, it was concluded that there was a positive correlation between the HU values and the DEXA for the BMD and between the HU values and the T-score. Based on the WHO guidelines, the T-scores of the lumbar vertebrae were classified into three groups. The mean HU values for the subjects in the normal group were 174.05 (95% confidence interval, 153-194.49), in the osteopenia group were 120.45 HU (95% confidence interval, 106.98-133.91), and in the osteoporosis group were 115 HU (95% confidence interval, 104.60-125.40). The differences in the mean HU values between the groups were significant.ConclusionOn analyzing the results of our study, we reached the conclusion that there is a positive correlation between the HU calculated from CT with automated exposure control and BMD calculated from the DEXA. Thus CT scans done for various reasons, for example, the abdomen, lumbar spine, etc. can provide us with information about the patient’s bone density as well. CT is a very popular, easily accessible, reproducible, and reliable tool for measuring HU values and thereby in the opportunistic screening of osteoporosis.

PurposeTo explore whether combining the Hounsfield unit (HU) values and vertebral bone quality (VBQ) scores can improve the BMD assessment in patients with lumbar degenerative diseases.MethodsThe HU values were measured by CT image, and VBQ scores were calculated by lumbar MRI image. The correlations of the opportunistic imaging parameters to the lowest T-scores were analyzed. Receiver-operating characteristic curve (ROC) analysis was used to evaluate the accuracy in detecting osteoporosis. Finally, the specificity and sensitivity of different combined methods of the HU values and VBQ scores in the diagnosis of osteoporosis were compared.ResultsPatients with osteoporosis had the lowest HU values and the highest VBQ scores. The correlation coefficients between the VBQ scores and the T-scores were smaller than HU values (L1 HU value: 0.702; average HU value:0.700; L1 VBQ score: -0.413; VBQ score: -0.386). The areas under the curve (AUCs) of the HU values were greater than those of the VBQ scores, and the AUCs of the L1 VBQ score were similar to the VBQ score (L1 HU value: 0.850; average HU value:0.857; L1 VBQ score: 0.704; VBQ score: 0.673). When combining the two imaging parameters in series, the specificity of the detection of osteoporosis was improved (L1 HU value and L1 VBQ score: 87.3%; Average HU value and VBQ score: 85.9%). When combining the two imaging parameters in parallel, the sensitivity of the detection of osteoporosis was improved (L1 HU value or L1 VBQ score: 88.1%; Average HU value or VBQ score: 91.5%).ConclusionsCombinations of the HU values and VBQ scores could improve the diagnostic performance of osteoporosis. In addition, considering the same diagnostic performance but easier measurement, parameters at the single-segment level were recommended to assist in the diagnosis of osteoporosis.

To evaluate vertebral Hounsfield Unit (HU) values on computed tomography (CT) in patients with ankylosing spondylitis (AS) compared to patients without AS and to examine differences in HU values between ankylosed and nonankylosed vertebrae in patients with AS. This cross-sectional study included 34 patients with AS and 73 patients without AS who underwent spinal CT between 2004 and 2022. HU values were measured from C3 to L5 in patients with AS and from L1 to L5 in patients without AS. Propensity score (PS) matching based on age and sex was performed to compare HU values between groups. Additionally, HU values were compared between ankylosed and nonankylosed vertebrae within the AS group. After PS matching, vertebral HU values were significantly lower in patients with AS than in patients without AS (136.4 vs. 197.1, p = 0.009). Among patients with AS, HU values were highest in the cervical spine, followed by the thoracic and lumbar regions. Ankylosed vertebrae showed significantly lower HU values than nonankylosed vertebrae across all spinal levels (p < 0.001). Vertebral HU values were lower in patients with AS compared to age- and sex-matched patients without AS. HU values were highest in the cervical spine, and ankylosed vertebrae consistently exhibited lower HU values than nonankylosed vertebrae across all spinal regions.

Background and Objectives: Although adjacent vertebral fractures (AVF) frequently occur after balloon kyphoplasty (BKP), their risk factors remain unclear. This retrospective study aimed to identify risk factors for AVF and evaluate the utility of Hounsfield unit (HU) values on preoperative vertebral computed tomography (CT) scans as predictors of its occurrence. Materials and Methods: We retrospectively evaluated 180 patients (46 male and 134 female individuals; mean age: 80.3 years; range: 60–94 years) who underwent BKP for osteoporotic vertebral fractures (OVFs) between 2021 and 2023 with at least 6 months of follow-up. The patients were categorized into the AVF (n = 31) and non-AVF (n = 149) groups. Analyzed variables included patient characteristics, fracture level, prior fractures, posterior wall injury, intravertebral cleft, vacuum phenomenon in adjacent intervertebral discs, injury-to-surgery interval, cement volume, kyphosis angles, wedge ratios, and HU values. HU values were measured at three levels on preoperative CT scans in the vertebrae above and below the treated segment. Cutoff HU values predictive of AVF were determined using receiver operating characteristic (ROC) curve analysis. Results: AVF incidence was 17.2% (31/180), with 71.0% occurring in the vertebrae above the treated level. HU values in all measured slices were significantly lower in the AVF group. The mean HU values in the upper vertebra were 61.1 ± 6.03 (AVF) and 84.7 ± 2.75 (non-AVF), and in the lower vertebra, 51.5 ± 8.44 and 81.0 ± 3.85, respectively. ROC analysis showed cutoff HU values of 79.3 and 61.0 for the upper and lower vertebrae, respectively. HU values were identified as independent AVF risk factors. Conclusions: Preoperative vertebral HU values are independent AVF predictors. Values below 79.3 in the upper or 61.0 in the lower vertebrae were linked to higher AVF risk, suggesting HU measurement is a simple, useful tool for preoperative risk assessment.

BackgroundThe fixation strength of bone screws depends on bone mineral density (BMD), so it is important to evaluate bone strength at fracture sites. Few studies have investigated BMD in the pelvis. The aims of this study were to measure the regional Hounsfield unit (HU) values in the cancellous bone of the acetabulum and pelvic ring and to compare these values between young and older patients.MethodsThis study enrolled young patients with high-energy trauma (aged 20–44 years; young group) and older patients with low-energy trauma (aged 65–89 years; older group). Patients without pelvic computed tomography (CT) scans, those with pelvic bone implants, and those who died were excluded. The HU values on the contralateral (non-fractured) side of the pelvis were measured on CT scans. The CT data were divided into 7 areas: the pubic bone, the anterior and posterior walls and roof of the acetabulum, the ischial tuberosity, the body of the ilium, and the third lumbar vertebra. The HU values in each area were compared between the young and older groups.ResultsSixty-one young patients and 154 older patients were included in the study. The highest HU value was in the roof of the acetabulum regardless of age and sex. HU values were significantly higher in the ischial tuberosity and body of the ilium and lower in the pubic bone and anterior wall. The HU values in all pelvic areas were significantly lower in the older group than in the young group, especially in the anterior area.ConclusionsHU values in the 6 pelvic areas were not uniform and were strongly related to load distribution. The HU distribution and age-related differences could explain the characteristic causes and patterns of acetabular fractures in the older and may help in surgical treatment.

ObjectiveUse of quantitative computed tomography (CT) to evaluate bone mineral density was suggested in the 1970s. Despite its reliability and accuracy, technical shortcomings restricted its usage, and dual-energy X-ray absorptiometry (DXA) became the gold standard evaluation method. Advances in CT technology have reduced its previous limitations, and CT evaluation of bone quality may now be applicable in clinical practice. The aim of this study was to determine if the Hounsfield unit (HU) values obtained from CT correlate with patient age and bone mineral density.MethodsA total of 128 female patients who underwent lumbar CT for back pain were enrolled in the study. Their mean age was 66.4 years. Among them, 70 patients also underwent DXA. The patients were stratified by decade of life, forming five age groups. Lumbar vertebrae L1-4 were analyzed. The HU value of each vertebra was determined by averaging three measurements of the vertebra's trabecular portion, as shown in consecutive axial CT images. The HU values were compared between age groups, and correlations of HU value with bone mineral density and T-scores were determined.ResultsThe HU values consistently decreased with increasing age with significant differences between age groups (p<0.001). There were significant positive correlations (p<0.001) of HU value with bone mineral density and T-score.ConclusionThe trabecular area HU value consistently decreases with age. Based on the strong positive correlation between HU value and bone mineral density, CT-based HU values might be useful in detecting bone mineral diseases, such as osteoporosis.

ObjectivesThis study aims to investigate whether Hounsfield unit (HU) value is correlated with intervertebral disc (IVD) degeneration (IVDD) by comparing premenopausal with menopausal women patients.MethodsA total of 101 female patients who underwent treatment in our hospital between February 2022 and February 2023 were retrospectively reviewed and included in this study. All patients were divided into either the premenopausal group or the menopausal group, according to age and menopause status. The changes in disc height index (DHI) on X-ray, the Hounsfield unit (HU) value on computed tomography (CT), and the area of the nucleus pulposus (NP) on magnetic resonance imaging (MRI) were assessed and compared between the two groups.ResultsThere is a significant difference in the Pfirrmann grading of T12-S1 discs between the premenopausal and menopausal groups; the menopausal group has more degenerated discs compared with the premenopausal group (P < 0.001). There is no significant difference in DHI measurements between the premenopausal and menopausal groups. HU values in the premenopausal group are greater compared with the menopausal group from T12 to S1 vertebrae (all P < 0.001). Regarding the NP area on MRI, the L2-L3 IV disc space have a bigger area in the premenopausal group compared with the menopausal group (P = 0.029), with no significant difference in other IVD segments.ConclusionsThe HU value on CT is significantly decreased with IVDD progression after menopause. The change in HU value could indirectly reflect vertebral bone mineral density. Therefore, the decline of estrogen after menopause leads to vertebral osteoporosis, which might contribute to IVDD progression.

To determine the predictive effect of Hounsfield unit (HU) values in the cervical vertebral body measured by computed tomography (CT) and T-scores measured by dual-energy X-ray absorptiometry (DXA) on Zero-P subsidence after anterior cervical discectomy and fusion (ACDF)with Zero-P. In addition, we evaluated the most reliable measurement of cervical HU values. We reviewed 76 patients who underwent single-level Zero-P fusion for cervical spondylosis. HU values were measured on CT images according to previous studies. Univariate analysis was used to screen the influencing factors of Zero-P subsidence, and then, logistic regression was used to determine the independent risk factors. The area under the receiver operating characteristic curve (AUC) was used to evaluate the ability to predict Zero-P subsidence. Twelve patients (15.8%) developed Zero-P subsidence. There were significant differences between subsidence group and non-subsidence group in terms of age, axial HU value, and HU value of midsagittal, midcoronal, and midaxial (MSCD), but there were no significant differences in lowest T-score and lowest BMD. The axial HU value (OR = 0.925) and HU value of MSCD (OR = 0.892) were independent risk factors for Zero-P subsidence, and the lowest T-score was not (OR = 1.186). The AUC of predicting Zero-P subsidence was 0.798 for axial HU value, 0.861 for HU value of MSCD, and 0.656 for T-score. Lower cervical HU value indicates a higher risk of subsidence in patients following Zero-P fusion for single-level cervical spondylosis. HU values were better predictors of Zero-P subsidence than DXA T-scores. In addition, the measurement of HU value in the midsagittal, midcoronal, and midaxial planes of the cervical vertebral body provides an effective method for predicting Zero-P subsidence.

The study aims to investigate the correlations between the T score, Hounsfield units (HU) value, and vertebral bone quality (VBQ) score, and to compare their discrimination capability for patients with osteoporotic vertebral compression fracture (OVCF). One hundred and sixty-three eligible participants were enrolled (49 OVCF group,114 non-OVCF group). The T score, HU value, and VBQ score were collected retrospectively. Then, those three parameters were compared between the OVCF and non-OVCF groups and the correlations among the three were assessed. Finally, the discrimination capability of those parameters was compared by the receiver operating characteristic (ROC) curves. The OVCF group showed a lower T score, lower HU value, and higher VBQ score (all P < 0.001) than the non-OVCF group. Correlations were observed among the T score, HU value, and VBQ score (all P < 0.001, HU VS. mean T score, r = 0.66; HU VS. minimum T score, r = 0.67; VBQ VS. mean/ minimum T score, r=-0.33; VBQ VS. HU, r=-0.45). The HU value indicated the maximum area under curve (AUC), followed by the VBQ score and then the T score. Moreover, the AUC of combining the VBQ score and the HU value was similar to that of the HU value. Both the HU value and the VBQ score had superior discrimination capability for patients with OVCF compared to the T score, especially for the HU value. For patients with routinely performed lumbar MRI or CT scans, the HU value or the VBQ score may provide alternative options for assessing the bone condition.

Hounsfield Unit Values as an Adjunct Diagnostic Tool: Investigating Its Relationship with Bone Mineral Density and Vertebral Bone Quality in Lumbar Degenerative Disease Patients

This study aimed to fabricate a heterogeneous phantom replicating the commercial Rando phantom by mixing plaster powder and polylactic acid (PLA) powder. Producing a heterogeneous phantom using Plaster and PLA is cheaper because it can be easily obtained in the commercial market. Additionally, patient-specific Quality Assurance can be easily performed because the phantom can be produced based on the patient’s CT image. PLA has been well studied in the field of radiation therapy and was found to be safe and effective. To match the mean Hounsfield unit (HU) values of the Rando phantom, the bone tissue was changed using plaster and 0–35% PLA powder until an appropriate HU value was obtained, and soft tissue was changed using the PLA infill value until an appropriate HU value was obtained. Bone tissue (200 HU or higher), soft issue (− 500 to 200 HU), and air cavity (less than − 500 HU) were modeled based on the HU values on the computed tomography (CT) image. The bone tissue was modeled as a cavity, and after three-dimensional (3D) printing, a solution containing a mixture of plaster and PLA powder was poured. To evaluate the bone implementation of the phantom obtained by the mixture of plaster and PLA powder, the HU profile of the CT images of the 3D-printed phantom using only PLA and the Rando phantom printed using only PLA was evaluated. The mean HU value for soft tissue in the Rando phantom (− 22.5 HU) showed the greatest similarity to the result obtained with an infill value of 82% (− 20 HU). The mean HU value for bone tissue (669 HU) showed the greatest similarity to the value obtained with 15% PLA powder (680 HU). Thus, for the phantom composed of plaster mixed with PLA powder, soft tissue was fabricated using a 3D printer with an infill value of 82%, and bone tissue was fabricated with a mixture containing 15% PLA powder. In the HU profile, this phantom showed a mean difference of 61 HU for soft tissue and 109 HU for bone tissue in comparison with the Rando phantom. The ratio of PLA powder and plaster can be adjusted to achieve an HU value similar to bone tissue. A simple combination of PLA powder and plaster enabled the creation of a custom phantom that showed similarities to the Rando phantom in both soft tissue and bone tissue.

Retrospective observational study. This study aimed to determine the predictive utility of Hounsfield unit (HU) values, derived from single-slice computed tomography (CT) images, for identifying postoperative pedicle screw (PS) loosening in patients undergoing lumbar interbody fusion. The HU values were specifically measured along the planned PS trajectory. PS loosening is a frequent complication following spinal fusion surgery, particularly in individuals with compromised bone quality. Although prior research has explored the correlation between screw loosening and general vertebral HU values or bone mineral density, the specific predictive capability of a simple, single-slice measurement along the screw path remains a gap in the literature. We retrospectively reviewed data from 47 patients (212 screws) who underwent lumbar interbody fusion between November 2020 and September 2022. Preoperative CT images were used to measure HU values in both the vertebral body and along the PS trajectories. Patients were then stratified into two groups based on the presence (L group, n=9) or absence (no-loosening [NL] group, n=38) of screw loosening identified on 1-year follow-up CT. Comparative analyses were conducted, followed by a receiver operating characteristic curve analysis to establish the optimal predictive HU cutoff. The incidence of postoperative screw loosening was 11.8% (25/212). While no significant inter-group differences were observed regarding age, bone mineral density, or vertebral body HU values, the PS trajectory HU was significantly lower in the L group (111±40) compared to the NL group (157±74) (p <0.001). Receiver operating characteristic curve analysis identified an optimal HU cutoff of 123. The area under the curve was 0.7106, with an odds ratio of 3.18, sensitivity of 0.31, and specificity of 0.41. Lower HU values measured along the PS trajectory using single-slice CT images were significantly associated with a higher risk of screw loosening. This straightforward method may serve as a valuable tool for identifying high-risk patients during the preoperative planning phase of spinal fusion surgery.