Correlations among Cervical, Thoracic, and lumbar Hounsfield Unit measurements for assessment of bone mineral density

OBJECTIVE

Bone mineral density assessment using Hounsfield Unit (HU) currently depends upon the availability of computed tomography (CT) of the lumbar spine. The primary aim of this study was to evaluate the associations among HU measurements of the cervical (CHU), thoracic (THU), and lumbar (LHU) spine. The secondary aim of this study was to analyze the influence of patient demographic and anthropometric characteristics on HU measurements.

METHODS

Radiographic records of 165 patients who underwent CT of the cervical, thoracic, and lumbar spine were retrieved. The CHU, THU, and LHU were calculated by obtaining the mean signal intensity from the medullary portions of C3-C7, T8-T12, and L1-L4 vertebral bodies.

RESULTS

Mean CHU, THU, and LHU values were 266.26 ± 88.69, 165.57 ± 55.06, and 166.45 ± 51.38. Significant differences of 100.69, 99.81, and 0.88 were observed between CHU and THU (p <.001), CHU and LHU (p <.001), and THU and LHU (p =.023). Correlations of 0.574, 0.488, and 0.686 were observed between CHU and THU (p <.001), CHU and LHU (p <.001), and THU and LHU (p <.001). No differences in HU based on sex, age, height, weight, or ethnicity were observed. Multivariate regression models demonstrated R2 values of 0.770 - 0.790 (p <.001) in prediction of LHU.

CONCLUSIONS

Hounsfield Unit measurements derived from the cervical and thoracic spine correlate with the validated lumbar Hounsfield Unit. Hounsfield Unit measurements do not vary based on sex, ethnicity, age, height, or weight.

High Endplate Hounsfield Units Value Indicate Intervertebral Disc Degeneration Following Transforaminal Lumbar Interbody Fusion Surgery

OBJECTIVE

Lumbar disc degeneration (LDD) is a common cause of low back pain and disability, and its prevalence increases with age. The aim of this study is to investigate whether endplate Hounsfield unit (HU) values have an effect on lumbar disc degeneration (LDD) after transforaminal lumbar interbody fusion (TLIF) surgery in patients with degenerative lumbar stenosis.

METHODS

This study was a retrospective analysis of patients who underwent TLIF surgery in January 2016 to October 2019. One hundred and fifty-seven patients who underwent TLIF surgery for degenerative lumbar stenosis were enrolled in this study. Demographic data was recorded. VAS and ODI values were compared to assess the surgical outcomes in patients with or without process of LDD after TLIF surgery. Correlation analysis was performed to investigate associations between LDD and endplate HU value. Binary logistic regression analysis was carried out to study relationships between the DDD and the multiple risk factors.

RESULTS

There was a statistically significant correlation between LDD, body mass index (BMI), age, paraspinal muscle atrophy, and total endplate scores (TEPS). Also, a strong and independent association between endplate HU value and LDD was found at every lumbar disc level (p < 0.01). After conditioning on matching factors, multivariate logistic regression analysis showed that higher endplate HU (odds ratio [OR]: 1.003, p = 0.003), higher TEPS (OR: 1.264, p = 0.002), higher BMI (odds ratio [OR]: 1.202, p = 0.002), a smaller cross-sectional area (CSA) of the paraspinal muscle preoperatively (OR: 0.096, p < 0.001) were significant predictors of LDD development after TLIF surgery.

CONCLUSIONS

There is a significant association between LDD and endplate HU value after TLIF surgery in patients with degenerative lumbar stenosis. Beyond that, results from this study provide a mechanism by which high endplate HU value predisposes to LDD after TLIF surgery.

Effect of psoas and gluteus medius muscles attenuation on hip fracture type

INTRODUCTION

Sarcopenia is defined as a progressive loss of muscle mass and function with increased age. The measurement of muscle mass and attenuation on the axial computed tomography (CT) scan has been reported to be a good indicator for sarcopenia in previous literature. This study aimed to compare muscle mass between the intertrochanteric fracture and femoral neck fracture groups by accurately measuring muscle mass around the hip joint using a CT scan.

METHODS

The cases were matched according to age and gender on a 1-to-1 basis. As a result, a total of 400 patients, 200 patients in each group with the same age and gender characteristics, were included in the study. At the disc of L4-L5 level, the cross-sectional area (CSA) of the psoas muscle was evaluated, and at the disc of L5-S1 level, the CSA of the psoas, iliacus and gluteus medius muscles were evaluated. In addition, attenuation was evaluated using the average Hounsfield Unit (HU) for the specific area.

RESULTS

The mean age of 400 patients (262 females, 138 male) included in the study was 78.49 ± 7.67 years. It was observed that the mean HU values of the patients in the femoral neck fracture group were significantly higher than the intertrochanteric fracture group (p < 0.001, p = 0.008; respectively). At the same time, the mean HU values of the gluteus medius muscle were higher in the femoral neck fracture group (p < 0.001), but in contrast with the psoas muscle, the CSA values of gluteus medius muscle were significantly higher in the intertrochanteric fracture group (p = 0.017).

CONCLUSIONS

Fatty degeneration of the psoas muscle among the muscles around the hip may affect the type of hip fracture. Elderly patients with strong psoas muscles may experience femoral neck fracture due to contraction and torsion during falling.

Predictive effects of admission white blood cell counts and hounsfield unit values on delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

OBJECTIVE

Neuroinflammatory response is deemed the primary pathogenesis of delayed cerebral ischemia (DCI) caused by aneurysmal subarachnoid hemorrhage (aSAH). Both white blood cell (WBC) count and Hounsfield Unit (HU) are gradually considered can reflect inflammation in DCI. This study aims to identify the relationship between WBC count and HU value and investigate the effects of both indicators in predicting DCI after aSAH.

METHODS

We enrolled 109 patients with aSAH admitted within 24 h of onset in our study. A multivariate logistic regression analysis was used to evaluate the admission WBC count, HU value, and combined WBC-HU associated with DCI. The receiver operating characteristic curve and area under the curve (AUC) were used to determine thresholds and detect the predictive ability of these predictors. These indicators were also compared with the established inflammation markers.

RESULTS

Thirty-six (33%) patients developed DCI. Both WBC count and HU value were strongly associated with the admission glucose level (ρ = .303, p = .001; ρ = .273, p = .004), World Federation of Neurosurgical Societies grade (ρ = .452, p < .001; ρ = .578; p < .001), Hunt-Hess grade (ρ = .450, p < .001; ρ = .510, p < .001), and modified Fisher scale score (ρ = .357, p < .001; ρ = .330, p < .001). After controlling these public variables, WBC count (ρ = .300, p = .002) positively correlated with HU value. An early elevated WBC (odds ratio [OR] 1.449, 95% confidence interval [CI]: 1.183-1.774, p < .001) count and HU value (OR 1.304, 95%CI: 1.149-1.479, p < .001) could independently predict the occurrence of DCI. However, only these patients with both WBC count and HU value exceeding the cut-off points (OR 36.89, 95%CI: 5.606-242.78, p < .001) were strongly correlated with DCI. Compared with a single WBC count (AUC 0.811, 95%CI: 0.729-0.892, p < .001) or HU value (AUC 0.869, 95%CI: 0.803-0.936, p < .001), the combined WBC-HU (AUC 0.898, 95%CI: 0.839-0.957, p < .001) demonstrated a better ability to predict the occurrence of DCI. Inspiringly, the prediction performance of these indicators outperformed the established inflammatory markers.

CONCLUSION

An early elevated WBC count and HU value could independently predict DCI occurrence between 4 and 30 days after aSAH. Furthermore, WBC count was positively correlated with HU value, and the combined WBC-HU demonstrated a superior prediction ability for DCI development compared with the individual indicator.

Attenuation Value in Adrenal Incidentalomas: A Longitudinal Study

Context

A tendency to grow has been reported in adrenal incidentalomas. However, long-term data regarding attenuation value, a measure of lipid content, are not available.

Aim

This study aims to collect radiological data (diameter in mm and attenuation value in Hounsfield units, HU) with computed tomography (CT) in adrenal incidentalomas, in order to compare baseline characteristics with the last follow-up imaging.

Design

This is a longitudinal study which included patients with a new diagnosis of adrenal incidentaloma, evaluated from January 2002 to June 2020.

Setting

Referral University-Hospital center.

Patients

Two hundred seventy-seven patients with 355 different cortical adenomas (baseline group) were evaluated at the first outpatient visit; the follow-up cohort consists of 181 patients with 234 adenomas (12-175 months after baseline). Inclusion criteria were conservative management and radiological features able to minimize malignancy or risk of progression.

Main Outcome Measure

CT modification according to endocrine function: autonomous cortisol secretion (ACS) if cortisol >50 nmol/L after 1-mg dexamethasone test (DST).

Results

At baseline CT, mean diameter was 18.7 mm and attenuation value was 0.8 HU (higher in ACS, 66 cases >10 HU), without modification in early imaging (12-36 months). The size increased over time (r = 0.289), achieving the largest differences after at least 60 months of follow-up (mean diameter, +2 mm; attenuation value, -4 HU), combined with a reduction in the attenuation value (r = -0.195, especially in patients with ACS). Lipid-poor adenomas (>10 HU) presented a reduced cortisol suppression after 1-mg DST, an increase in size and the largest decrease in attenuation value during follow-up. Univariate analysis confirmed that larger adenomas presented reduced suppression after DST and increase in size during follow-up.

Conclusions

Growth is clinically modest in adrenal incidentaloma: the first follow-up CT 5 years after baseline is a reasonable choice, especially in ACS. Mean density is increased in patients with ACS and overt hypercortisolism. Mean density reduces during follow-up in all adrenal adenomas, suggesting an increase in lipid content, especially in those with ACS.

[Local spinal profile following operative treatment of thoracolumbar and lumbar fractures : Impact of reduction technique and bone quality]

Hintergrund

Ziel der Operation von Wirbelsäulenverletzungen ist eine stabile Ausheilung in physiologischer Stellung. Für offene und perkutane Operationen stehen unterschiedliche Techniken zur Verfügung.

Fragestellung

Das Ausmaß der offenen Reposition und das Retentionspotenzial der Techniken nach AOSpine (AT) und nach Kluger (KT) sollen verglichen werden. Der Einfluss von Frakturmorphologie, Alter, Geschlecht und Knochenqualität auf Reposition und Retention werden untersucht.

Material und Methoden

In dieser monozentrischen retrospektiven Kohortenstudie wurden Daten von Patienten mit traumatischen thorakolumbalen und lumbalen Frakturen untersucht, welche entweder mit AT oder KT reponiert wurden. Mittels bisegmentalen Grund-Deckplatten-Winkels (bGDW) wurde die Stellung des verletzten Wirbelsäulenabschnitts beschrieben. Normalwerte für die bGDW wurden anhand von Literaturdaten angenommen. Die Veränderung des bGDW im zeitlichen Verlauf wurde unter Einbeziehung der Knochenqualität in Hounsfield Units (HU), der Verletzungsschwere nach AOSpine und des Patientenalters und -geschlechts analysiert.

Ergebnisse

Es wurden 151 Datensätze ausgewertet. Beide Methoden reponieren vom Umfang nicht unterschiedlich (AT 10 ± 6°, KT 11 ± 8°; p = 0,786). Im Follow-up trat ein Korrekturverlust von −5 ± 4° auf. Die Technik (p = 0,998) hatte keinen Einfluss darauf. Die Frakturmorphologie zeigte einen knapp signifikanten Einfluss (p = 0,043). Niedrige HU korrelierten mit geringerem Repositionsumfang (r = 0,241, p < 0,003) und größerem Korrekturverlust (r = 0,272, p < 0,001) signifikant, aber schwach. In der Altersgruppe 50 bis 65 Jahre wiesen 21 % der Männer und 43 % der Frauen eine Knochenqualität von HU < 110 auf. Alter und HU korrelieren signifikant (r = −0,701, p < 0,001).

Diskussion

Die Techniken sind gleichwertig bezüglich der Repositions- und Retentionseigenschaften. Der hohe Anteil von Patienten mit HU < 110 in der Gruppe unter 65 Jahren bei Frauen und Männern und der Einfluss auf Reposition und Retention weisen auf die Notwendigkeit einer präoperativen Knochendichtemessung hin.

Evaluation of a commercial synthetic computed tomography generation solution for magnetic resonance imaging-only radiotherapy

Purpose

To evaluate the Siemens solution generating Synthetic computed tomography (sCT) for magnetic resonance imaging (MRI)‐only radiotherapy (RT).

Method

A retrospective study was conducted on 47 patients treated with external beam RT for brain or prostate cancer who underwent both MRI and CT for treatment planning. sCT images were generated from MRI using automatic bulk densities segmentation. The geometric accuracy of the sCT was assessed by comparing the Hounsfield Units (HU) difference between sCT and CT for bone structures, soft‐tissue, and full body contour. VMAT plans were computed on the CT for treatment preparation and then copied and recalculated with the same monitor units on the sCT using the AcurosXB algorithm. A 1%‐1mm gamma analysis was performed and DVH metrics for the Planning Target Volume (PTV) like the D_mean and the D_98% were compared. In addition, we evaluate the usability of sCT for daily position verification with cone beam computed tomography (CBCT) for 14 prostate patients by comparing sCT/CBCT registration results to CT/CBCT.

Results

Mean HU differences were small except for the skull (207 HU) and right femoral head of four patients where significant aberrations were found. The mean gamma pass rate was 73.2% for the brain and 84.7% for the prostate and D_mean were smaller than 0.5%. Large differences for the D_98% of the prostate group could be correlated to low Dice index of the PTV. The mean difference of translations and rotations were inferior to 3.5 mm and 0.2° in all directions with a major difference in the anterior‐posterior direction.

Conclusion

The performances of the software were shown to be similar to other sCT generation algorithms in terms of HU difference, dose comparison and daily image localization.

The Influence of Surgical Experience and Bone Density on the Accuracy of Static Computer-Assisted Implant Surgery in Edentulous Jaws Using a Mucosa-Supported Surgical Template with a Half-Guided Implant Placement Protocol-A Randomized Clinical Study

The aim of our randomized clinical study was to analyze the influence of surgical experience and bone density on the accuracy of static computer-assisted implant surgery (CAIS) in edentulous jaws using a mucosa-supported surgical template with a half-guided implant placement protocol. Altogether, 40 dental implants were placed in the edentulous jaws of 13 patients (novice surgeons: 18 implants, 6 patients (4 male), age 71 ± 10.1 years; experienced surgeons: 22 implants, 7 patients (4 male), age 69.2 ± 4.55 years). Angular deviation, coronal and apical global deviation and grey level measurements were calculated for all implants by a blinded investigator using coDiagnostiX software. 3DSlicer software was applied to calculate the bone volume fraction (BV/TV) for each site of implant placement. There were no statistically significant differences between the two study groups in either of the primary outcome variables. There was a statistically significant negative correlation between angular deviation and both grey level measurements (R-value: −0.331, p < 0.05) and BV/TV (R-value: −0.377, p < 0.05). The results of the study suggest that surgical experience did not influence the accuracy of implant placement. The higher the bone density at the sites of implant placement, the higher the accuracy of static CAIS.

Factors affecting success in the treatment of proximal ureteral stones larger than 1 cm with extracorporeal shockwave lithotripsy in adult patients

The aim of the study was to analyze the factors predicting success for the treatment of proximal ureteral stones larger than 1 cm with extracorporeal shockwave lithotripsy (SWL) in adult patients. Between January 2014 and December 2018, 480 adult patients in total underwent SWL and data were retrospectively evaluated. Patients with multiple ureteral stones, solitary kidney, congenital abnormality, skeletal system abnormality, history of previous urinary system surgery and SWL, renal insufficiency, patients who could not tolerate SWL and pediatric patients were excluded from the study. The remaining 415 patients were divided into two groups as success (Group 1, n = 307) and failure (Group 2, n = 108). The overall success rate was 73.9%. The values of stone size, Hounsfield Unit (HU), skin to stone distance (SSD), ureteral wall thickness (UWT), proximal ureter diameter, renal pelvis diameter, hydronephrosis grade, and duration of renal colic were significantly higher in Group 2 compared to Group 1. In binary logistic regression analyses, HU, UWT, and proximal ureter diameter were found to be independent predictors. HU, UWT, and proximal ureter diameter had sensitivity and specificity of 92-92%, 88-23%, and 87-46%, with cutoff values of 740 HU, 2.5 mm and 8.5 mm, respectively. The area under the curve values were 0.96, 0.97, and 0.96 for HU, UWT, and proximal ureter diameter, respectively. The CT-based parameters, including HU, UWT, and proximal ureter diameter are independent predictive factors with excellent accuracy for the treatment of proximal ureteral stones larger than 1 cm with SWL in adult patients. Based on these factors, SWL can be considered for proximal ureteral stones larger than 1 cm.

Hounsfield Units on Lumbar Computed Tomography for Predicting Regional Bone Mineral Density

Objective

Bone mineral density (BMD) is a very important factor in spinal fusion surgery using instrumentation. Our aim was to investigate the utility of Hounsfield units (HU) obtained from preoperative lumbar computed tomography (CT) to predict osteoporosis coupling with data of quantitative computed tomography (QCT) and dual X-ray absorptiometry (DEXA).

Methods

We reviewed 180 patients that underwent both QCT and lumbar CT for spine surgery. HU was retrospectively calculated on the lumbar CT of 503 lumbar vertebrae from L1 to L3. Femur DEXA was performed in all patients and spine DEXA was tested in 120 patients (331 vertebrae). BMD was grouped as osteoporosis (QCT<80mg/cm³, DEXA T score≤-2.5) and non-osteoporosis (QCT≥80mg/cm³, DEXA T score>-2.5) for comparison of HU value.

Results

HU value and BMD showed significant correlations. The optima cut-off value based on QCT was higher than that of DEXA scans which had the best correlation for predicting osteoporosis. ROC curve analysis demonstrated that HU value with QCT of 146 has a sensitivity of 94.3% and a specificity of 87.5% for osteoporosis.

Conclusions

Significant correlation was found between HU measurement and BMD value. These findings provide evidence that HU measurement can be established as a means for predicting osteoporosis before spine fusion surgery with reduced radiation hazard.

Computed tomography: a beneficial diagnostic tool for the evaluation of the canine prostate?

BACKGROUND

Prostatic diseases in intact male dogs are common. However, studies about the computed tomographic (CT) examination of the prostate in dogs are rare. The aim of the present study was to evaluate age related-changes in the canine prostate with the help of the CT and to evaluate whether measuring Hounsfield Units (HUs) in different morphological conditions of the prostate is of diagnostic value. Fifty pre- and post-contrast CT scans of the prostate of dogs were evaluated and divided into three groups according to the tissue structure: Group1 dogs with homogenous prostate tissue (16/50); group 2 with prostate cysts (26/50) and group 3 with inhomogeneous prostate tissue (8/50). The prostatic dimensions were measured and the ratio between length, height and width and the sixth lumbar vertebra was calculated. Median values of prostatic attenuation measured in HUs, using regions of interests (ROIs) were determined on pre- and post- contrast scans over the whole length of the prostate. The results were compared to the dog's age. Furthermore, the CT Images were compared with the results of ultrasonography (47/50).

RESULTS

On pre-contrast scans HUs within ROIs placed in the prostate did not differ statistically significantly between the different morphological groups (1: 37.7; 2: 36.3; 3: 39.8 HU). HUs within on the post- contrast scans showed statistically significant differences between the groups. Group one had a mean density of 93.6 HU, group two had a mean density of 106.1 HU and group three had one of 138.2 HU. The prostatic size in the first group was smaller than in the other groups, whereas the largest prostates were found in the second group. In six cases the post-contrast CT scan showed results that differed from the ultrasound examination. Dogs had a homogenous tissue in ultrasonography while the CT scan revealed an inhomogeneous tissue structure.

CONCLUSIONS

The CT examination can be a beneficial diagnostic tool for examining the prostatic size and for evaluating the prostatic tissue. The different HUs reflected age-related changes and alterations in the prostate while measuring the density of the prostate. Contrast agent application enables a more specific analysis of the prostate to be carried out and for precise changes in tissue structure to be observed.

Comparison of CT-Number and Gray Scale Value of Different Dental Materials and Hard Tissues in CT and CBCT

INTRODUCTION

Computed tomography (CT) and cone-beam CT (CBCT) are valuable diagnostic aids for many clinical applications. This study was designed to compare the gray scale value (GSV) and Hounsfield unit (HU) of selected dental materials and various hard tissues using CT or CBCT.

METHODS AND MATERIALS

Three samples of all test materials including amalgam (AM), composite resin (CR), glass ionomer (GI), zinc-oxide eugenol (ZOE), calcium-enriched mixture (CEM) cement, AH-26 root canal sealer (AH-26), gutta-percha (GP), Coltosol (Col), Dycal (DL), mineral trioxide aggregate (MTA), zinc phosphate (ZP), and polycarbonate cement (PC) were prepared and scanned together with samples of bone, dentin and enamel using two CBCT devices, Scanora 3D (S3D) and NewTom VGi (NTV) and a spiral CT (SCT) scanner (Somatom Emotion 16 multislice spiral CT);. Subsequently, the HU and GSV values were determined and evaluated. The data were analyzed by the Kruskal-Wallis and Mann-Whitney U tests. The level of significance was determined at 0.05.

RESULTS

There were significant differences among the three different scanners (P<0.05). The differences between HU/GSV values of 12 selected dental materials using NTV was significant (P<0.05) and for S3D and SCT was insignificant (P>0.05). All tested materials showed maximum values in S3D and SCT (3094 and 3071, respectively); however, bone and dentin showed low/medium values (P<0.05). In contrast, the tested materials and tissues showed a range of values in NTV (366 to15383; P<0.05).

CONCLUSION

Scanner system can influence the obtained HU/GSV of dental materials. NTV can discriminate various dental materials, in contrast to S3D/SCT scanners. NTV may be a more useful diagnostic aid for clinical practice.

The influence of the patient size and geometry on cone beam-computed tomography hounsfield unit

The objective of this work is to study the influence of the patient size and geometry on CBCT Hounsfield Unit and the accuracy of calibration Hounsfield Unit to electron density (HU-ED) using patient specific HU-ED mapping method for dose calculation. Two clinical cases, namely nasopharyngeal carcinoma (NPC) case and prostate case for 4 patients with different size and geometry were enrolled to assess the impact of size and geometry on CBCT Hounsfield Unit. The accuracy of the patient specific HU-ED mapping method was validated by comparing dose distributions based on planning CT and CBCT, dose-volume based indices and the digitally reconstructed radiograph (DRR) by analyzing their line profile plots. Significant differences in Hounsfield unit and line profile plots were found for NPC and prostate cases. The doses computed based on planning CT data sets and CBCT datasets for both clinical cases agree to within 1% for planning target volumes and 3% for organs at risk. The data shows that there are high dependence of HU on patient size and geometry; thus, the use of one CBCT HU-ED calibration curve made of one size and geometry will not be accurate for use with a patient of different size and geometry.