Evaluation of Enhancement Pattern of Malignant Lung Lesion During Contrast Enhanced Computed Tomography - Cross Sectional Study.

Background: At present, lung cancer is a leading cause of cancer death in the world. Most of the patients are asymptomatic at the early stages of the disease and manifest at the advanced stage. It is broadly classified into two types based on histopathology, Non-small cell lung cancer (NSCLC), the predominant type, and Small cell lung cancer (SCLC). Â Our study aimed to evaluate the enhancement pattern of malignant lung lesion during contrast-enhanced computed tomography. Methodology: A cross-sectional study was conducted on 34 patients with lung cancer after clearance from the Institutional Ethical Committee. Contrast enhanced computed tomography (CECT) Thorax was performed by 16 slice Multi-Detector computed tomography (MDCT )machine, and the tumor's pre and post-contrast Hounsfield Unit (HU) value was measured in the area of highest density. Results: Out of the 34 patients, Squamous cell carcinoma and adenocarcinoma were seen in 15 patients in each group, whereas small cell carcinoma was found in 4 patients. Pre and post-contrast mean HU value was 39.5 (SD= 2.95) HU and 72.13 (SD= 4.21) HU for adenocarcinoma, 34.6 (SD=2.61) HU and 63.8(SD=2.88) HU for squamous cell carcinoma and 31.00 (SD=1.41) HU and 55.7 (SD=2.75) HU for small cell carcinoma. The significant of density difference was measured using paired t-test (p<0.05). Conclusion: All histopathological subtypes of lung cancer showed significant post-contrast enhancement (>20HU) during the CECT study. Evaluation of enhancement pattern of lung mass by measuring pre and post-contrast HU value will help the radiologist to predict the histopathological type of lung cancer.

Are Hounsfield Unit Measurements of Bony Absorption Changes in Cholesteatoma Helpful?

Abstract Introduction High-resolution computed tomography (HRCT) scans of the temporal bone are used to assess the bony erosion of the middle-ear structures whenever cholesteatoma is suspected. Objective To study the differences in HRCT Hounsfield unit (HU) index measurements of middle-ear bony structures between an ears with and without cholesteatoma. Methods A retrospective study of 59 patients who underwent surgery due to unilateral cholesteatoma. The HRCT HU index of the scutum, of three middle-ear ossicles, of the lateral semicircular canal (LSCC), and of the fallopian canal was measured in both ears. A comparison was made between the cholesteatoma and the non-cholesteatomatous ear (control). All measurements were conducted by an otolaryngologist. To assess the interobserver bias, 10% of the samples were randomly and independently assessed by another otolaryngologist and a neuroradiologist who were blinded. Results The average HU index was lower in the ear with cholesteatoma when compared with the non-cholesteatomatous ear. While the differences were statistically significant regarding the measurements of the scutum (516.02 ± 311.693 versus 855.64 ± 389.999; p = 0.001), the malleus (1049.44 ± 481.765 versus 1413.47 ± 313.376; p = 0.01), and the incus (498.03 ± 264.184 versus 714.25 ± 405.631; p = 0.001), the differences in the measurements of the LSCC (1042.34 ± 301.066 versus 1154.53 ± 359.609; p = 0.69) and of the fallopian canal (467.19 ± 221.556 versus 543.51 ± 263.573; p = 0.108) were not significantly different between both groups. The stapes was immeasurable in both groups due to its small size. Conclusion Hounsfield unit index measurements are a useful tool that may aid in the diagnosis of early-stage cholesteatoma.

Computed tomography findings outcome endoscopic sinus surgery / Монголын Анагаах Ухаан

Background@#Endoscopic sinus surgery (ESS) is the main surgical approach in the treatment of chronic rhinosinusitis (CRS) after failure of medical treatment.@*Objective@#The goal of this study was to evaluate computed tomography (CT) findings associated endoscopic sinus surgery.@*Materials and Methods@#17-73 ages of 200 CRS patients who were operated endoscopic sinus surgery at department of ENT of First Central Hospital between November 2019 and November 2020, involved in this study. Subjects were divided into 2 groups: 1) CRS with NP 2) CRS without NP. CT changes were evaluated according to the Lund-Mackay, Hoover score, Hounsfield unit before and after surgery. Statistical analysis was performed with Stata 12.1.@*Result@#Of the total subjects analysed, 112(56%) were male and 88 (44%) were female. Average age of subjects was 38.4±13.9. Male: female gender ratio of patients was 1.27:1. @*Conclusion@#Endoscopic sinus surgery for CRS is effective according to the evaluation of Lund-Mackay, Hoover and Hounsfield unit, and it was statistically significant (p<0.0001).

Evaluation of Value of Computed Tomography Attenuation (Hounsfield Unit Value) Measured along the Dural Venous Sinuses on Non-contrast Computed Tomography Scan in Diagnosing Cerebral Venous Thrombosis

context: Cerebral venous sinus thrombosis (CVST) previously believed to be an uncommon cerebrovascular event, accounting for0.5–1% of cases of stroke, affecting 1.32/100,000 person/year. CVST is a disease of young adults (<50 years old) predominantlyand is diagnosed based on clinical suspicion with confirmatory neuroimaging.Aims: This study aims to prospectively evaluate the Hounsfield unit (H.U) value of cerebral venous sinus on non-contrastcomputerized tomography (NCCT) scan and to assess its predictive value in diagnosing cerebral venous thrombosis and toevaluate whether standardizing venous sinus H.U value measurements to those of the corresponding internal cerebral arterywould improve diagnostic accuracy.Materials and Methods: In our study, a total of 80 clinically suspected case of CVST were included and NCCT head scan was donethen confirmed by M.R. venography (gold standard). Of 80 cases, a total of 38 cases were diagnosed as CVST on M.R. venographywhich was considered as Group B and rest 42 cases were normal on M.R. venography which was considered as Group A.Statistical Analysis: Average HU and H:H ratio were compared using two-tailed t-test, and linear regression analysis wasused to assess correlation between hematocrit (HCT) and HU.Results: Linear regression analysis showed positive correlation between HCT with computed tomography attenuation (HU)among both the groups (P < 0.005). H:H ratio (HU/HCT) for cutoff point of 1.645 had sensitivity of 71.1%, 97.6% specificity,and 96.4% PPV. A cutoff value of 1.335 for standardized measurement with internal carotid arteries (ICA) had 71.1% sensitivity,81% specificity, and 77.1% PPV.Conclusion: We conclude that average HU, H:H ratio, and standardized with ICA were the best predictor for sinus thrombosis.

Machine Learning Model to Predict Osteoporotic Spine with Hounsfield Units on Lumbar Computed Tomography

OBJECTIVE: Bone mineral density (BMD) is an important consideration during fusion surgery. Although dual X-ray absorptiometry is considered as the gold standard for assessing BMD, quantitative computed tomography (QCT) provides more accurate data in spine osteoporosis. However, QCT has the disadvantage of additional radiation hazard and cost. The present study was to demonstrate the utility of artificial intelligence and machine learning algorithm for assessing osteoporosis using Hounsfield units (HU) of preoperative lumbar CT coupling with data of QCT. METHODS: We reviewed 70 patients undergoing both QCT and conventional lumbar CT for spine surgery. The T-scores of 198 lumbar vertebra was assessed in QCT and the HU of vertebral body at the same level were measured in conventional CT by the picture archiving and communication system (PACS) system. A multiple regression algorithm was applied to predict the T-score using three independent variables (age, sex, and HU of vertebral body on conventional CT) coupling with T-score of QCT. Next, a logistic regression algorithm was applied to predict osteoporotic or non-osteoporotic vertebra. The Tensor flow and Python were used as the machine learning tools. The Tensor flow user interface developed in our institute was used for easy code generation. RESULTS: The predictive model with multiple regression algorithm estimated similar T-scores with data of QCT. HU demonstrates the similar results as QCT without the discordance in only one non-osteoporotic vertebra that indicated osteoporosis. From the training set, the predictive model classified the lumbar vertebra into two groups (osteoporotic vs. non-osteoporotic spine) with 88.0% accuracy. In a test set of 40 vertebrae, classification accuracy was 92.5% when the learning rate was 0.0001 (precision, 0.939; recall, 0.969; F1 score, 0.954; area under the curve, 0.900). CONCLUSION: This study is a simple machine learning model applicable in the spine research field. The machine learning model can predict the T-score and osteoporotic vertebrae solely by measuring the HU of conventional CT, and this would help spine surgeons not to under-estimate the osteoporotic spine preoperatively. If applied to a bigger data set, we believe the predictive accuracy of our model will further increase. We propose that machine learning is an important modality of the medical research field.

Machine Learning Model to Predict Osteoporotic Spine with Hounsfield Units on Lumbar Computed Tomography

OBJECTIVE: Bone mineral density (BMD) is an important consideration during fusion surgery. Although dual X-ray absorptiometry is considered as the gold standard for assessing BMD, quantitative computed tomography (QCT) provides more accurate data in spine osteoporosis. However, QCT has the disadvantage of additional radiation hazard and cost. The present study was to demonstrate the utility of artificial intelligence and machine learning algorithm for assessing osteoporosis using Hounsfield units (HU) of preoperative lumbar CT coupling with data of QCT.METHODS: We reviewed 70 patients undergoing both QCT and conventional lumbar CT for spine surgery. The T-scores of 198 lumbar vertebra was assessed in QCT and the HU of vertebral body at the same level were measured in conventional CT by the picture archiving and communication system (PACS) system. A multiple regression algorithm was applied to predict the T-score using three independent variables (age, sex, and HU of vertebral body on conventional CT) coupling with T-score of QCT. Next, a logistic regression algorithm was applied to predict osteoporotic or non-osteoporotic vertebra. The Tensor flow and Python were used as the machine learning tools. The Tensor flow user interface developed in our institute was used for easy code generation.RESULTS: The predictive model with multiple regression algorithm estimated similar T-scores with data of QCT. HU demonstrates the similar results as QCT without the discordance in only one non-osteoporotic vertebra that indicated osteoporosis. From the training set, the predictive model classified the lumbar vertebra into two groups (osteoporotic vs. non-osteoporotic spine) with 88.0% accuracy. In a test set of 40 vertebrae, classification accuracy was 92.5% when the learning rate was 0.0001 (precision, 0.939; recall, 0.969; F1 score, 0.954; area under the curve, 0.900).CONCLUSION: This study is a simple machine learning model applicable in the spine research field. The machine learning model can predict the T-score and osteoporotic vertebrae solely by measuring the HU of conventional CT, and this would help spine surgeons not to under-estimate the osteoporotic spine preoperatively. If applied to a bigger data set, we believe the predictive accuracy of our model will further increase. We propose that machine learning is an important modality of the medical research field.

Evaluation and Correlation between craniofacial bone densities and C1 and C2 cervical vertebrae using multislice computed tomography / Avaliação e Correlação entre as densidades ósseas craniofaciais e vértebras cervicais C1 e C2 por meio de tomografia computadorizada multislice

Objective: To evaluate the use of computed tomography (CT) as an osteoporosis screening tool, evaluating the relation between the bone mineral density (BMD) from maxilla and mandible with the cervical vertebrae, using the Hounsfield units (HU). Material and Methods: It was included in this study a convenience sample of 118 multislice CT examinations from patients who underwent maxilla, mandible and cervical vertebrae (C1 and C2) simultaneously scans. For each patient, the following regions on both sides of head CT scans were assessed in sagittal slice: above maxillary central and lateral incisors apexes; maxillary tuberosity; mandible head; mandible body endosteum; mandible body trabeculae and vertebrae C1 and C2. HU were measured in each area using a 0.5 cm region of interest (ROI) positioned in the center of the slice. Results: It was verified that there is a correlation between the BMD of the C1 and C2 vertebrae and the anterior region of the maxilla. It was not found correlation between the vertebrae, C1 and C2, and the other structures analyzed. Conclusions: This study showed that this method can be a good screening tool to diagnosis of osteoporosis, when evaluated the correlation between C1 and C2 vertebrae and anterior region of maxilla. More studies are necessary to evaluate the possibility of using CT as an osteoporosis screening tool. (AU)

Objetivos: Avaliar o uso da tomografia computadorizada como ferramenta de rastreamento da osteoporose, avaliando a relação entre a densidade mineral óssea da maxila e mandíbula com as vértebras cervicais, utilizando as unidades de Hounsfield. Material e métodos: Neste estudo foram incluidos uma amostra de 118 pacientes submetidos à exames de tomografia computadorizada multislice que apresentavam as estruturas anatomicas da maxila, mandibula e as vértebras cervicais (C1 e C2) simultaneamente. Para cada paciente, as seguintes regiões dos dois lados da tomografia computadorizada da cabeça foram avaliadas em corte sagital: acima dos ápices dos incisivos centrais e laterais superiores; tuberosidade maxilar; cabeça da mandíbula; endósteo do corpo da mandíbula; trabéculas do corpo da mandíbula e vértebras C1 e C2. As unidades de Hounsfield foram medidas em cada área usando uma região de interesse de 0,5 cm (ROI) posicionada no centro do corte. Resultados: Verificou-se uma correlação positiva entre a densidade mineral óssea das vértebras C1 e C2 e a região anterior da maxila. Não foram encontradas correlação entre as vértebras C1 e C2 e as demais estruturas analisadas. Conclusão: Este estudo mostrou que esse método pode ser uma ferramenta de triagem para o diagnóstico de osteoporose, quando avaliada a correlação entre as vértebras C1 e C2 e a região anterior da maxila. Mais estudos são necessários para avaliar a possibilidade do uso da tomografia computadorizada como ferramenta de rastreamento da osteoporose. (AU)

Hounsfield unit value has null effect on thyroid nodules at 18F-FDG PET/CT scans

ABSTRACT Objectives: Detection rate of thyroid nodules is increasing with the use of new imaging modalities, especially in screening for malignancies. Positron emission tomography/computed tomography (PET/ CT)-positive thyroid nodules should be differentiated for malignancy to avoid unnecessary operations and further follow-up. Most trials evaluate the role of SUVmax, but there is no definitive information about the utility of Hounsfield unit (HU) values for prediction of malignancy. This study aimed to evaluate the HU values beside SUVmax for detecting malignancy risk of PET/CT-positive thyroid nodules. Subjects and methods: Results of 98 cancer patients who had fine needle aspiration biopsy (FNAB) for thyroid nodules detected on PET/CT between January 2011 and December 2015 were assessed. The FNABs and surgical pathological results were recorded. Results: FNABs revealed benign results in 32 patients (32.7%), malignant in 18 (18.4%), non-diagnostic in 20 (20.4%), and indeterminate in 28 (28.5%). Twenty-four patients underwent thyroidectomy. The mean HU values were not significantly different in benign and malignant nodules (p = 0.73). However, the mean SUVmax was significantly higher (p < 0.001) in malignant ones. Area under curve (AUC) was 0.824 for SUVmax; the cut-off value was over 5.55 (p < 0.001), with 80% sensitivity, 84.5% specificity. Conclusions: Our current study demonstrated that HU value does not add any additional valuable information for discriminating between malignant and benign thyroid nodules. We also defined a SUV cut-off value of 5.55 for malignant potential of thyroid nodules detected on PET/CT Arch Endocrinol Metab. 2018;62(4):460-5

Evaluation Of Renal Stones By Computed Tomography And Its Correlation With Urine Ph And Biochemical Analysis

Introduction: The aim of the study is to assess the composition of renal stones by non chemical analysis that is by use of computed tomography (CT) values in Hounsfield Units (HU) and to compare the results of biochemical stone analysis collected post surgically done in biochemistry lab. Methodology: This is a prospective study, included pa-tients in age group of 25 –60yrs. Patients who were referred to radiology department from Urology and also pa-tients referred from surgery with complaints of loin pain, groin pain, hematuria, crystalluria were recruited for the study. About 100 patients were screened with first line modality of ultrasound evaluation for identifying the pres-ence of stone in kidney, later on positive confirmation from ultrasound evaluation they were further subjected to CT scan evaluation. “Urine was collected from all the patients with renal stones and urine pH was measured. Stones collected post surgically were used for the biochemical analysis to know the chemical composition of the stonesRESULTS: The stone removed from the patients of this group contain high calcium content. Most of the stones re-moved from bladder comprises two categories 1.uric acid (mainly) 2.large stones more than 20 mm size were proved to be calcium stones possibly related to greater sunlight exposure, resulting in increase in insensible fluid losses and increase in vitamin D production. We obtained a reference from hounsfield units value from stones collected post surgically from the urological department. The stones are categorized into three types -Pure highly reflective crystal-line white stones, Stones which appears most mostly black, Complex mild yellow stones. Conclusion: CT may enable accurate in vivo characterization of kidney stone composition.

Limited Evaluation of Image Quality Produced by a Portable Head CT Scanner

Introduction: Computed tomography (CT) is the preferred diagnostic toolkit for head and brain imaging of head injury. A recent development is the invention of a portable CT scanner that can be beneficial from a clinical point of view. Aim: To compare the quality of CT brain images produced by a fixed CT scanner and a portable CT scanner (CereTom). Methods: This work was a single-centre retrospective study of CT brain images from 112 neurosurgical patients. Hounsfield units (HUs) of the images from CereTom were measured for air, water and bone. Three assessors independently evaluated the images from the fixed CT scanner and CereTom. Streak artefacts, visualisation of lesions and grey–white matter differentiation were evaluated at three different levels (centrum semiovale, basal ganglia and middle cerebellar peduncles). Each evaluation was scored 1 (poor), 2 (average) or 3 (good) and summed up to form an ordinal reading of 3 to 9. Results: HUs for air, water and bone from CereTom were within the recommended value by the American College of Radiology (ACR). Streak artefact evaluation scores for the fixed CT scanner was 8.54 versus 7.46 (Z = -5.67) for CereTom at the centrum semiovale, 8.38 (SD = 1.12) versus 7.32 (SD = 1.63) at the basal ganglia and 8.21 (SD = 1.30) versus 6.97 (SD = 2.77) at the middle cerebellar peduncles. Grey–white matter differentiation showed scores of 8.27 (SD = 1.04) versus 7.21 (SD = 1.41) at the centrum semiovale, 8.26 (SD = 1.07) versus 7.00 (SD = 1.47) at the basal ganglia and 8.38 (SD = 1.11) versus 6.74 (SD = 1.55) at the middle cerebellar peduncles. Visualisation of lesions showed scores of 8.86 versus 8.21 (Z = -4.24) at the centrum semiovale, 8.93 versus 8.18 (Z = -5.32) at the basal ganglia and 8.79 versus 8.06 (Z = -4.93) at the middle cerebellar peduncles. All results were significant with P-value < 0.01. Conclusions: Results of the study showed a significant difference in image quality produced by the fixed CT scanner and CereTom, with the latter being more inferior than the former. However, HUs of the images produced by CereTom do fulfil the recommendation of the ACR.

The effects of pentoxifylline adminstration on fracture healing in a postmenopausal osteoporotic rat model / 한국실험동물학회지

Previous studies report positive effects of pentoxifylline (PTX) alone or in combination with other drugs on some pathologic bone diseases as well as an ability to accelerate osteogensis and fracture healing in both animal models and human patients. The aim of this present study was to evaluate the effects of PTX administration on Hounsfield unit and bone strength at catabolic response (bone resorbing) of a fracture in an experimental rat model of ovariectomy induced osteoporosis (OVX-D). Thirty adult female rats were divided into groups as follows: 1 (OVX, control, no treatment); 2 (OVX, sham: daily distilled water); 3 (OVX, daily alendronate: 3 mg/kg); 4 (OVX, twice daily 100 mg/kg PTX) and 5 (OVX, PTX+alenderonate). OVX was induced by bilateral ovariectomy in all rats. A complete standardized osteotomy of the right femur was made after 3.5 months. PTX and alendronate treatments were performed for eight weeks. Then, rats were euthanized and had its right femur subjected to computerized tomography scanning for measuring Hounsfield unit; eventually, the samples were sent for a three point bending test for evaluation of the bone strength. Administration of PTX with 200 mg/kg and alendronate alone and in combination showed no significant alteration in Hounsfield unit and biomechanical properties of repairing callus of the complete osteotomy compared with the control group. Results showed increased bending stiffness and stress high load mean values of repairing complete osteotomy in PTX-treated rats compared to the control OVX-D.

Correlation between hounsfield unit value and stone composition in nephrolithiasis / Correlação entre os valores de unidades hounsfield e a composição cristalina na nefrolitías

OBJECTIVE: To examine whether the Hounsfield Unit value predicts calcium oxalate monohydrate stones in patients who are undergoing percutaneous nephrolithotomy. METHOD: 119 patients who underwent percutaneous nephrolithotomy were prospectively evaluated between February 2012 and August 2014. Using thin cuts, the highest single-energy computed tomography attenuation value within a pixel was measured for each stone. Data regarding age and gender were assessed before surgery. The extracted stones were analyzed using infrared spectrophotometry. RESULTS: By receiver operating characteristics analysis, a cutoff value of 1548 Hounsfield Unit and an age of 42.5 years were used to determine the likelihood of a stone being composed of calcium oxalate monohydrate. A higher Hounsfield Unit value and increased age augmented the chances of a stone being composed of calcium oxalate monohydrate. In general, females had a greater likelihood of harboring calcium oxalate monohydrate stones than males. CONCLUSION: The maximum Hounsfield Unit value, as determined by unenhanced single-energy computed tomography in association with gender, predicts the presence of calcium oxalate monohydrate stones in patients who are undergoing percutaneous nephrolithotomy.

OBJETIVO: verificar se as medidas de atenuação de raios-X em Unidades Hounsfied (HU) preveem os cálculos de oxalato de cálcio mono-hidratado (OCM) em pacientes tratados através de nefrolitotripsia percutânea. MÉTODO: 119 pacientes submetidos a tratamento por nefrolitotripsia percutânea foram avaliados prospectivamente entre fevereiro de 2012 e Agosto de 2014. Utilizando cortes tomográficos finos, o maior valor de atenuação de raios-X para um pixel utilizando tomografia convencional sem contraste foi determinado para cada cálculo. Dados laboratoriais foram avaliados antes da cirurgia. Os cálculos extraídos foram analisados utilizando-se espectrofotometria no infravermelho. RESULTADOS: Através de análise por curva ROC (receicer operating characteristic) um valor de corte de 1548 HU e uma idade de 42,5 anos foram utilizadas para determinar a probabilidade de um cálculo ser composto de OCM. Valores superiores de atenuação de raios-X e de idade aumentaram as chances de um cálculo ser composto de OCM. Em geral, as mulheres apresentaram uma maior probabilidade de ter cálculos de OCM do que os homens. CONCLUSÃO: O valor da medida de atenuação máxima em Unidades Hounsfield de um cálculo, como o determinado pela tomografia computadorizada convencional sem contraste, em associação com o gênero preveem a presença de cálculos de OCM em pacientes submetidos a tratamento por nefrolitotripsia percutânea.

Density of Orbital Fat and Extraocular Muscle in Thyroid-Associated Myopathy and Idiopathic Orbital Myositis

PURPOSE: To perform and compare differential diagnosis of patients with thyroid-associated myopathy, idiopathic orbital myositis and normal controls based on orbital computed tomography. Orbital fat and extraocular muscle densities were quantified using Hounsfield Unit (HU) and their characteristics were compared and analyzed. METHODS: From February 2005 to January 2013, orbital computed tomography was performed on 90 eyes of 47 thyroid-associated myopathy patients, 18 eyes of 14 idiopathic orbital myositis patients and 280 eyes of 140 normal subjects. The average values of orbital fat and extraocular muscle densities were measured and compared using HU. The density differences between the patients with thyroid-associated myopathy and the normal group were analyzed by age, clinical activity score, ocular protrusion and disease duration. RESULTS: In the thyroid-associated myopathy group, orbital fat and extraocular muscle densities were -87.8 +/- 12.5 HU and 48.7 +/- 7.1 HU, respectively. In the idiopathic orbital myositis group, the orbital fat and extraocular muscle densities were 79.9 +/- 9.9 HU and 49.2 +/- 9.1 HU, respectively. There was a statistically significant lower result of orbital fat in the thyroid-associated myopathy group (p = 0.002), however, the extraocular muscle density did not show a statistically significant difference (p = 0.775). The orbital fat and extraocular muscle densities of the normal group were -79.0 +/- 11.2 HU and 54.3 +/- 6.3 HU, respectively. There were significantly lower results in both orbital fat and extraocular muscle densities in the thyroid-associated myopathy group than normal group (p = 0.000). In active cases and those accompanied by ocular protrusion, there was no significant difference in orbital fat density (p = 0.345 and p = 0.952, respectively), while extraocular muscle density significantly decreased (p = 0.007 and p = 0.003, respectively). CONCLUSIONS: A difference between the orbital fat and extraocular muscle densities in thyroid-associated myopathy and idiopathic orbital myositis could be quantitatively found using HU and orbital computed tomography.

Correlation between Bone Mineral Density Measured by Dual-Energy X-Ray Absorptiometry and Hounsfield Units Measured by Diagnostic CT in Lumbar Spine

OBJECTIVE: Use 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. METHODS: A 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. RESULTS: The 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. CONCLUSION: The 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.

The bone density of mandible as the aging process in Koreans

INTRODUCTION: This study compared the alveolar bone density of the mandible according to gender, age and position using Cone-beam computed tomography (CT). MATERIALS AND METHODS: The maxillofacial CT scan data was obtained from 60 Korean patients. In addition, the alveloar bone density of 5 males and 5 females with normal occlusion aged from 10 to 70 years was measured at the buccal cortical bone, cancellous bone and lingual cortical bone, as well as at the position of the incisors, canines, premolars and molars. RESULTS: The age-specific mean bone density was highest in patients in their third decade. The buccal cortical bone of the molars showed the highest bone density. Males in their fifties and sixties had a higher bone density in the cancellous bone in the region of the premolars and the buccal cortical bone of the molars, respectively, than females but there was no significant difference between males and females in the other parts. The cancellous bone density was highest in those in their twenties and thirties, and tended to decline up to their seventh decade. CONCLUSION: These results revealed a significantly different bone density according to gender, age and position in the Korean population. In addition, it is possible to predict the bone density based on these results.

The study of bone density assessment on dental implant sites

INTRODUCTION: Bone density is one of the important factors for the long term success of endosseous implants. The bone density varies from site to site and from patient to patient. A preoperative evaluation of the bone density is quite useful to oral surgeons for planning dental implantation. More accurate information on the bone density will help surgeons identify suitable implant sites, thereby increase the success rate of dental implantation. This study examined the correlation between the bone density measured preoperatively by computed tomography (CT) and the implant primary stability measured by resonance frequency analysis. Furthermore, the effects of the implant sites, gender, age and generalized systemic disorder patients on the bone density and primary implant stability were examined. MATERIALS AND METHODS: One hundred and fourteen patients were selected. None of the patients had undergone a tooth extraction or bone graft history in the previous year. Preoperatively, the patients underwent CT scanning to evaluate the Hounsfield unit (HU), and resonance frequency analysis (RFA) was used to evaluate the implant primary stability at the time of implant installation. All implants were 4.0 mm diameter and 11.5 mm length US II. All patients were recorded and the HU and implant stability quotient (ISQ) value were evaluated according to the sites, gender and age. RESULTS: The highest HU values were found in the mandibular anterior site (827.6+/-151.4), followed by the mandibular molar site (797+/-135.1), mandibular premolar site (753.8+/-171.2), maxillary anterior site (726.3+/-154.4), maxillary premolar site (656.7+/-173.8) and maxillary molar site (621.5+/-164.9). The ISQ value was the highest in the mandibular premolar site (81.5+/-2.4) followed by the mandibular molar site (80.0+/-5.7), maxillary anterior site (77.4+/-4.1), mandibular anterior site (76.4+/-11.9), maxillary premolar site (74.2+/-14.3) and maxillary molar site (73.7+/-7.4). The mean HU and ISQ value were similar in females and males. (HU: P=0.331, ISQ: P=0.595) No significant difference was also found in the age group respectively. However, the correlation coefficients between the variables showed a closed correlation between the HU and ISQ value. CONCLUSION: These results showed close correlation between the bone density (HU) and primary stability value (ISQ) at the time of implant installation (Correlation coefficients=0.497, P<0.01). These results strengthen the hypothesis that it might be possible to predict and quantify the initial implant stability and bone density from a presurgical CT diagnosis. These results strengthen the hypothesis that it might be possible to predict and quantify the initial implant stability and bone density from a presurgical CT diagnosis.

Measurement of hard tissue density of head phantom based on the HU by using CBCT / 대한구강악안면방사선학회지

PURPOSE: The purpose of this study was to determine a conversion coefficient for Hounsfield Units(HU) to material density (g cm-3) obtained from cone-beam computed tomography (CBMercuRay(TM)) data and to measure the hard tissue density based on the Hounsfield scale on dental head phantom. MATERIALS AND METHODS: CT Scanner Phantom (AAPM) equipped with CT Number Insert consists of five cylindrical pins of materials with different densities and teflon ring was scanned by using the CBMercuRay(TM)(Hitachi, Tokyo, Japan) volume scanner. The raw data were converted into DICOM format and the HU of different areas of CT number insert measured by using CBWorks(TM). Linear regression analysis and Student t-test were performed statistically. RESULTS: There was no significant difference (P>0.54) between real densities and measured densities. A linear regression was performed using the density, rho (g cm-3), as the dependent variable in terms of the HU(H). The regression equation obtained was rho=0.00072H-0.01588 with an R(2) value of 0.9968. Density values based on the Hounsfield scale was 1697.1+/-24.9 HU in cortical bone, 526.5+/-44.4 HU in trabecular bone, 2639.1+/-48.7 HU in enamel, 1246.1+/-39.4 HU in dentin of dental head phantom. CONCLUSION: CBCT provides an effective option for determination of material density expressed as Hounsfield Units.

Computed Tomographic Evaluation of Bone Quality of the Mandible Reconstructed by Particular Cellular Bone and Marrow Combined with Platelet Rich Plasma / Oral Science International

Concerning the bone structures of the mandible reconstructed by particular cellular bone and marrow (PCBM), platelet rich plasma (PRP) and tray, we have examined the possibility of implant insertion by clarifying the morphological conditions in each compact and cancellous bone on computed tomography (CT), and by observing the differences in their CT values.Using the computer software program Sim Plant (Materialize Dental, Leuven, Belgium), we morphologically observed 6 cases of implant inserted area after mandibular reconstruction and 11 cases of native bone, and examined the differences in their CT values. The osseointegration rate of each inserted implant was also evaluated.Compared with the native bone group, the PCBM reconstruction group had generally thin compact bone. In the over-3cm-length PCBM reconstruction group, the average CT value was 259.7 ± 94.4 HU (n = 3) in the cancellous bone, whereas in the native bone group, the average CT value was 528.9 ± 140.1 HU (n = 10). Therefore, the PCBM reconstruction group showed significantly lower CT value than the native bone group. However, in the under-3cm-length group, the PCBM reconstruction group showed no significant difference compared with the native bone group. The osseointegration rate of the inserted implants almost 6 months after insertion was 100% in the PCBM reconstruction group and 94.1% in the native bone group.Although the PCBM reconstructed bone had thinner cortical bone and showed lower CT value compared with the native bone, implant insertion was possible.

CT Number Measurement of Residual Foreign Bodies in Face

PURPOSE: Computed tomography theoretically should improve detection of foreign bodies and provide more information of adjacent soft tissues. And the CT scanner and PACS program proved to be an excellent instrument for detection and localization of most facial foreign bodies above certain minimum levels of detectability. The severity of injury in penetrating trauma to the face, it is often underestimated by physical examination. Diagnosis of a retained foreign object is always critical. METHODS: From March, 2005 to February 2008 a study was done with 200 patients who had facial trauma. Axial and coronal CT images were obtained with a General Electric(Milwaukee, Wis) 9800 CT scanner at 130kV, 90mA, with a 2-mm section thickness and a 512x512 matrix. RESULTS: Axial and coronal CT images at various window widths should be used as the first imaging modality to detect facial foreign bodies. The attenuation coefficients for the metallic and nonmetallic foreign bodies ranged from -437 to +3071 HU. As a general rule, metallic foreign bodies produced more Hounsfield artifacts than nonmetallic foreign bodies, thus providing a clue to their composition. All of the metallic foreign bodies were represented by a single peak and had a maximum attenuation coefficient of +3071 HU. Of the nonmetallic foreign bodies, glass had an attenuation coefficient that ranged from +105 to +2039, while plastic had a much lower coefficient that ranged from -62 to -35. wood had the lowest range of attenuation coefficients: -491 to -437. CONCLUSION: The PACS program allows one to distinguish metallic from nonmetallic foreign bodies and to individually identify the specific composition of many nonmetallic foreign bodies. This program does not, however, allow identification of the specific composition of a metallic foreign body. We recommend this type of software program for CT scanning of any patient with an injury to the face in which a foreign body is suspected.

Stress distribution following face mask application using different finite element models according to Hounsfield unit values in CT images / 대한치과교정학회지

OBJECTIVE: The result of finite element analysis depends on material properties, structural expression, density of element, and boundar or loading conditions. To represent proper elastic behavior, a finite element model was made using Hounsfield unit (HU) values in CT images. METHODS: A 13 year 6 month old male was used as the subject. A 3 dimensional visualizing program, Mimics, was used to build a 3D object from the DICOM file which was acquired from the CT images. Model 1 was established by giving 24 material properties according to HU. Model 2 was constructed by the conventional method which provides 2 material properties. Protraction force of 500g was applied at a 45 degree downward angle from Frankfort horizontal (FH) plane. RESULTS: Model 1 showed a more flexible response on the first premolar region which had more forward and downward movement of the maxillary anterior segment. Maxilla was bent on the sagittal plane and frontal plane. Model 2 revealed less movement in all directions. It moved downward on the anterior part and upward on the posterior part, which is clockwise rotation of the maxilla. CONCLUSION: These results signify that different outcomes of finite element analysis can occur according to the given material properties and it is recommended to use HU values for more accurate results.