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Hounsfield Units (hounsfield + unit)

Distribution by Scientific Domains

Medical Sciences	87%

Selected Abstracts

Do radiologists agree on the quality of computed tomography enterography?

JOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 4 2009
Kari Ersland
Summary This study aimed to assess variation between radiologists evaluating the quality of multi-detector computed tomography enterography. For 40 consecutive examinations, three experienced radiologists independently rated the following quality variables: % length of adequately filled bowel, bowel lumen diameters, bowel wall delineation, superior mesenteric vein, and bowel wall enhancement, artefacts, and total quality. We calculated the mean difference between observers with standard deviation (SD) for continuous variables and % total agreement, exact Fleiss kappa, and P -values (McNemar's test) for categorical variables. Depending on bowel segment (duodenum distal to bulb, jejunum, ileum, terminal ileum), mean difference between observers ranged from two to 33 (SD from 11 to 32) for % length of adequately filled bowel judged subjectively, 0,2 (SD 0,3) mm for smallest bowel lumen diameter and 0,4 (SD 3,7) mm for largest bowel lumen diameter. Agreement on bowel wall delineation was 80%/kappa 0.50 in duodenum, 90%/kappa 0.57 in jejunum, 75%/kappa 0.14 in ileum and 88%/kappa 0.17 in terminal ileum, where ratings differed between observers (P < 0.04). Agreement was 65%/kappa 0.18 for bowel wall enhancement judged subjectively. For contrast enhancement measured in Hounsfield Units, mean difference between observers ranged from two to 11 (SD 12,15) in normal jejunum wall and zero to one (SD 4,5) in the superior mesenteric vein depending on observer pair. Agreement was 78%/kappa 0.12 for image artefacts. Rating of total examination quality (good/optimal versus poor/very poor) differed between observers (P < 0.01); agreement was 60%/kappa 0.41. Many subjective evaluations varied between observers. We believe that measurements of bowel lumen diameters and contrast enhancement may be preferable. [source]

Computed tomographic measurements of thigh muscle cross-sectional area and attenuation coefficient predict hip fracture: The health, aging, and body composition study

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 3 2010
Thomas Lang
Abstract Fatty infiltration of muscle, myosteatosis, increases with age and results in reduced muscle strength and function and increased fall risk. However, it is unknown if increased fatty infiltration of muscle predisposes to hip fracture. We measured the mean Hounsfield unit (HU) of the lean tissue within the midthigh muscle bundle (thigh muscle HU, an indicator of intramuscular fat), its cross-sectional area (CSA, a measure of muscle mass) by computed tomography (CT), bone mineral density (BMD) of the hip and total-body percent fat by dual X-ray absorptiometry (DXA), isokinetic leg extensor strength, and the Short Physical Performance Battery (SPPB) in 2941 white and black women and men aged 70 to 79 years. Sixty-three hip fractures were validated during 6.6 years of follow-up. Proportional hazards regression analysis was used to assess the relative risk (RR) of hip fracture across variations in thigh muscle attenuation, CSA, muscle strength, and physical function for hip fracture. In models adjusted by age, race, gender, body mass index, and percentage fat, decreased thigh muscle HU resulted in increased risk of hip fracture [RR/SD,=,1.58; 95% confidence interval (CI) 1.10,1.99], an association that continued to be significant after further adjustment for BMD. In models additionally adjusted by CSA, muscle strength, and SPPB score, decreased thigh muscle HU but none of the other muscle parameters continued to be associated with an increased risk of hip fracture (RR/SD,=,1.42; 95% CI 1.03,1.97). Decreased thigh muscle HU, a measure of fatty infiltration of muscle, is associated with increased risk of hip fracture and appears to account for the association between reduced muscle strength, physical performance, and muscle mass and risk of hip fracture. This characteristic captures a physical characteristic of muscle tissue that may have importance in hip fracture etiology. © 2010 American Society for Bone and Mineral Research [source]

Calcific healing of a crown root fracture of a maxillary central incisor evaluated with spiral computed tomography and hounsfield units: a case report

DENTAL TRAUMATOLOGY, Issue 6 2008
Suresh Nandini
Calcific healing of a complicated oblique crown root fracture is rarely reported in literature. This article highlights the calcific healing of a traumatized maxillary central incisor with crown root fracture. This unique observation of healing following trauma was confirmed with the use of spiral computed tomography and Hounsfield units. [source]

Assessment of correlation between computerized tomography values of the bone, and maximum torque and resonance frequency values at dental implant placement

JOURNAL OF ORAL REHABILITATION, Issue 12 2006
I. TURKYILMAZ
summary, The aim of this study was to determine the bone density in the designated implant sites using computerized tomography (CT), the fastening torque values of dental implants, and the implant stability values using resonance frequency analysis. Further aim was to evaluate a possible correlation between bone density, fastening torque and implant stability. Eighty-five patients were treated with 158 Brånemark System implants. CT machine was used for preoperative evaluation of the jawbone for each patient, and bone densities were recorded in Hounsfield units (HU). The fastening torque values of all implants were recorded with the OsseoCare equipment. Implant stability measurements were performed with the Osstell machine. The average bone density and fastening torque values were 751·4 ± 256 HU and 39·7 ± 7 Ncm for 158 implants. The average primary implant stability was 73·2 ± 6 ISQ for seventy implants. Strong correlations were observed between the bone density, fastening torque and implant stability values of Brånemark System TiUnite MKIII implants at implant placement (P < 0·001). These results strengthen the hypothesis that it may be possible to predict and quantify initial implant stability and bone quality from pre-surgical CT diagnosis. [source]

Relationship between vascular calcification, arterial stiffness and bone mineral density in a cross-sectional study of prevalent Australian haemodialysis patients

NEPHROLOGY, Issue 1 2009
NIGEL D TOUSSAINT
SUMMARY Background: Cardiovascular disease in dialysis patients is associated with increased vascular calcification (VC) and arterial stiffness, both inversely correlated with bone mineral density (BMD). Few studies have correlated VC in the dialysis population with measurements of BMD and arterial compliance. Methods: We report cross-sectional data on 45 haemodialysis (HD) patients assessing the prevalence of VC and its associations. Patients had computed tomography scans through abdominal aorta and superficial femoral arteries (SFA) to determine VC, pulse wave velocity (PWV) using SphygmoCor device measuring arterial stiffness, and dual-energy X-ray absorptiometry (DXA) to determine BMD. Results: Patients, 64% male, 38% diabetic, had median age 58 years. Mean PWV was 8.7 ± 3.5 m/s and median aortic VC score 488.1 ± 298 Hounsfield units, with 91% having aortic VC present. In univariate linear regression analysis, aortic VC correlated positively with length of HD (P = 0.03) and diabetes (P = 0.06). Increasing PWV was positively associated with age (P = 0.001), diabetes (P = 0.05) and VC (aortic P = 0.08, SFA P = 0.01). In multivariate regression analysis, length of HD and diabetes were significantly associated with aortic VC, whereas age and diabetes were associated with SFA VC and PWV. Mean lumbar spine and femoral neck T-scores on DXA were 0.14 and ,1.66 respectively. Conclusion: Increased VC and reduced arterial compliance, both closely related, are common in Australian HD patients. Both are associated with diabetes and increasing age, and greater aortic VC is seen with longer duration of dialysis. [source]

Evaluation of postmortem changes in tissue structure in the bottlenose dolphin (Tursiops truncatus)

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 8 2007
Megan F. Mckenna
Abstract Postmortem changes in geometry, density, and sound speed within organs and tissues (melon, bone, blubber, and mandibular fat) of the dolphin head were evaluated using computed tomography (CT) scans of live and postmortem bottlenose dolphins (Tursiops truncatus). Specimens were classified into three different treatment groups: live, recently dead, and frozen followed by thawing. Organs and tissues in similar anatomical regions of the head were compared in CT scans of the specimens to identify postmortem changes in morphology. In addition, comparisons of Hounsfield units in the CT scans were used to evaluate postmortem changes in the density of melon, bone, blubber, and mandibular fat. Sound speed measurements from melon, blubber, connective tissue, and muscle were collected from fresh and frozen samples in the same specimen to evaluate effects due to freezing and thawing process on sound speed measurements. Similar results in tissue and organ geometry, density, and sound speed measurements suggested that postmortem material is a reliable approximation for live melon, bone, blubber, muscle, connective tissue, and mandibular fat. These results have implications for examining viscoelastic properties and the accuracy of simulating sound transmission in postmortem material. Anat Rec, 290:1023,1032, 2007. © 2007 Wiley-Liss, Inc. [source]

Influence of long-term cigarette smoking on immunoglobulin E-mediated allergy, pulmonary function, and high-resolution computed tomography lung densitometry in elderly patients with asthma

CLINICAL & EXPERIMENTAL ALLERGY, Issue 1 2004
F. Mitsunobu
Summary Background Smoking is the most important cause of chronic obstructive pulmonary disease (COPD). However, the influence of cigarette smoking on the pathogenesis of asthma in the elderly remains controversial. This study attempted to clarify the influence of cigarette smoking on elderly asthmatics. Methods Forty-eight asthmatics over 70 years old (25 ex-smokers and 23 never-smokers) and 20 patients with COPD over 70 years old (all ex-smokers) were studied to determine the influence of cigarette smoking on IgE-mediated allergy (total IgE, IgE antibodies against inhalant allergens, bronchial hyper-responsiveness (BHR), generation of leukotriene (LT) B4 and C4), pulmonary function, and the relative area of lung showing attenuation values less than ,950 Hounsfield units (RA950) on high-resolution computed tomography scans. Results The incidence of positive IgE antibodies against inhalant allergens, BHR, and the generation of leukotriene B4 (LTB4) by leucocytes were significantly increased in patients with a history of smoking compared with those without. Residual volume (%RV) was significantly increased, and diffusing capacity for carbon monoxide was significantly decreased in ex-smokers with asthma and COPD compared with never-smokers with asthma. Inspiratory RA950 and ratio of expiratory RA950 to inspiratory RA950 were significantly larger in asthmatics with a smoking history than in those without, and in COPD patients than in asthmatics. Conclusion Cigarette smoking enhances the production of IgE antibodies, BHR, and generation of LTB4 by leucocytes in elderly asthmatics. Increased hyper-inflation or emphysematous changes of the lungs expressed by increased RA950, closely related to %RV, was more frequently observed in ex-smokers compared with never-smokers. [source]