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Biomedical subjects

F L Thaete

Publications and source records attributed to F L Thaete.

At least 19 recordsLinked to original sources
PubMed2001

Plasma fatty acids, adiposity, and variance of skeletal muscle insulin resistance in type 2 diabetes mellitus.

Skeletal muscle insulin resistance (IR) is typically severe in type 2 diabetes mellitus (DM). However, the factors that account for interindividual differences in the severity of IR are not well understood. The current study was undertaken to examine the respective roles of plasma FFA, regional adiposity, and other metabolic factors as determinants of the severity of skeletal muscle IR in type 2 DM. Twenty-three subjects (12 women and 11 men) with type 2 DM underwent positron emission tomography imaging using [18F]2-fluoro-2-deoxyglucose during euglycemic insulin infusions (120 mU/min x m2) to measure skeletal muscle IR, using Patlak analysis of the tissue activity curves. Body composition analysis included body mass index, fat mass, and fat-free mass by dual energy x-ray tomography, and computed tomography determinations of visceral adiposity, thigh adipose tissue distribution, and muscle composition. Body mass index, fat mass, subfascial adiposity in the thigh, and visceral adipose tissue (VAT) were all significantly related to skeletal muscle IR (r = -0.48 to -0.63; P < 0.01). However, the strongest simple correlate of IR in skeletal muscle was insulin-suppressed plasma FFA (r = -0.81; P < 0.001). VAT was the sole component of adiposity that significantly correlated with insulin-suppressed plasma FFA concentration (r = 0.64; P < 0.001). These findings indicate that the severity of skeletal muscle IR in type 2 DM is closely related to the IR of suppressing lipolysis and that plasma fatty acids and VAT are key elements mediating the link between obesity and skeletal muscle IR in type 2 DM.

Adipose Tissue↗
PubMed2001

Performance of CT in detection of bowel injury.

OBJECTIVE: The objective of our study was to identify relevant and reliable CT signs of bowel injury, to determine the overall performance of CT in detection of bowel injuries, and to establish the effect of the training level of radiologists on this performance. MATERIALS AND METHODS: Abdominal CT scans of 112 patients with blunt abdominal trauma were prospectively and retrospectively reviewed. Fifty patients had proven bowel injuries (with or without other visceral injuries), whereas 62 patients had no bowel injury and comprised the comparison or control group. Thirty-one of the 62 patients in the comparison group had surgical proof of abdominal but not bowel or mesenteric injuries. The retrospective review of the 112 CT scans was performed randomly and individually by nine radiologists unaware of the diagnosis, including three faculty abdominal radiologists, three senior residents in training, and three junior residents in training. Individual performance and group performance were evaluated by receiver operating characteristic analysis, and interobserver agreement was tested. Individual CT signs as relevant predictors of bowel injury were identified by logistic regression. RESULTS: Relevant predictors of bowel injury included mesenteric infiltration, bowel wall thickening, extravasation of vascular or enteric contrast agent, and the presence free air. In the retrospective blinded review, CT showed good to excellent interobserver reliability for individual CT signs as well as for diagnosis of bowel and visceral injuries. Faculty radiologists tended to diagnose injuries with greater accuracy and confidence, but they showed significantly better performance than residents only in diagnosing duodenal perforation. For the prospective CT diagnosis of bowel injury, CT had a sensitivity of 64%, an accuracy of 82%, and a specificity of 97%. CONCLUSION: Bowel injuries are challenging to diagnose on CT. Radiologists with various levels of experience and expertise can achieve accurate and reproducible results using a variety of CT criteria.

Abdominal Injuries↗
PubMed2000

Thigh adipose tissue distribution is associated with insulin resistance in obesity and in type 2 diabetes mellitus.

BACKGROUND: Adipose tissue (AT) content of the thigh is generally not considered to be associated with insulin resistance (IR), but it is unclear whether the distribution of AT in the thigh is a determinant of IR. OBJECTIVE: We investigated whether subcompartments of AT within the thigh are determinants of IR. DESIGN: Midthigh AT, muscle composition, and insulin sensitivity were compared in 11 obese patients with type 2 diabetes mellitus (DM); 40 obese, glucose-tolerant (GT) and 15 lean, GT volunteers; and 38 obese subjects who completed a weight-loss program. Midthigh AT area measured with computed tomography was partitioned into 3 components: subcutaneous AT (SCAT), AT beneath the fascia (SFAT), and AT infiltrating muscle groups (IMAT). Muscle attenuation characteristics were determined. RESULTS: Obese DM and obese GT subjects had lower insulin sensitivity than lean GT subjects. SCAT was greater in obesity, yet did not correlate with insulin sensitivity. SFAT was approximately 8% of total thigh AT and correlated with insulin sensitivity. IMAT was highest in obese DM, and although it accounted for only approximately 3% of thigh AT, it was a strong correlate of insulin sensitivity. Mean attenuation was highest in lean subjects and was associated with higher insulin sensitivity. Weight loss reduced the amount of thigh AT, the proportion of thigh IMAT, and the amount of low-density thigh muscle. CONCLUSIONS: SFAT and IMAT are markers of IR in obesity and DM although they are much smaller than SCAT, which does not predict IR. Muscle composition reflecting increased fat content is also associated with IR.

Absorptiometry, Photon↗
PubMed2000

Composition of skeletal muscle evaluated with computed tomography.

Computed tomography (CT) can yield quantitative imaging data from detailed maps of linear attenuation coefficients within tissue. The attenuation characteristics of skeletal muscle and adipose tissue can be quantified in vivo to provide information about the composition of skeletal muscle and the distribution of adipose tissue within muscle. Several studies have taken advantage of this utility to quantify skeletal muscle composition and fatty infiltration of muscle, in particular to quantify the attenuation characteristics of muscle as a marker of its lipid content. In this manner we found that the mean muscle attenuation of skeletal muscle reflects an increase in its fat content in obesity, and that this regional body composition parameter is strongly related to insulin-resistant glucose metabolism. In addition, muscle composition and adipose tissue distribution within muscle may be altered with clinical weight-loss interventions. CT may also provide important information about the changes in muscle mass and composition with aging and disease, which may, in turn, affect the muscle's function. In summary, CT can provide important quantitative data on the composition of muscle, and the distribution of adipose tissue within it, and this may be important in examining the relationships among skeletal muscle metabolism, lipid accumulation within muscle, and muscle function.

Adipose Tissue↗
PubMed2000

Subdivisions of subcutaneous abdominal adipose tissue and insulin resistance.

Whereas truncal (central) adiposity is strongly associated with the insulin resistant metabolic syndrome, it is uncertain whether this is accounted for principally by visceral adiposity (VAT). Several recent studies find as strong or stronger association between subcutaneous abdominal adiposity (SAT) and insulin resistance. To reexamine the issue of truncal adipose tissue depots, we performed cross-sectional abdominal computed tomography, and we undertook the novel approach of partitioning SAT into the plane superficial to the fascia within subcutaneous adipose tissue (superficial SAT) and that below this fascia (deep SAT), as well as measurement of VAT. Among 47 lean and obese glucose-tolerant men and women, insulin-stimulated glucose utilization, measured by euglycemic clamp, was strongly correlated with both VAT and deep SAT (r = -0.61 and -0.64, respectively; both P < 0.001), but not with superficial SAT (r = -0.29, not significant). Also, VAT and deep SAT followed a highly congruent pattern of associations with glucose and insulin area under the curve (75-g oral glucose tolerance test), mean arterial blood pressure, apoprotein-B, high-density lipoprotein cholesterol, and triglyceride. Superficial SAT had markedly weaker association with all these parameters and instead followed the pattern observed for thigh subcutaneous adiposity. We conclude that there are two functionally distinct compartments of adipose tissue within abdominal subcutaneous fat and that the deep SAT has a strong relation to insulin resistance.

Abdomen↗
PubMed2000

Skeletal muscle attenuation determined by computed tomography is associated with skeletal muscle lipid content.

The purpose of this investigation was to validate that in vivo measurement of skeletal muscle attenuation (MA) with computed tomography (CT) is associated with muscle lipid content. Single-slice CT scans performed on phantoms of varying lipid concentrations revealed good concordance between attenuation and lipid concentration (r(2) = 0.995); increasing the phantom's lipid concentration by 1 g/100 ml decreased its attenuation by approximately 1 Hounsfield unit (HU). The test-retest coefficient of variation for two CT scans performed in six volunteers was 0.51% for the midthigh and 0.85% for the midcalf, indicating that the methodological variability is low. Lean subjects had significantly higher (P < 0.01) MA values (49.2 +/- 2.8 HU) than did obese nondiabetic (39.3 +/- 7.5 HU) and obese Type 2 diabetic (33.9 +/- 4. 1 HU) subjects, whereas obese Type 2 diabetic subjects had lower MA values that were not different from obese nondiabetic subjects. There was also good concordance between MA in midthigh and midcalf (r = 0.60, P < 0.01), psoas (r = 0.65, P < 0.01), and erector spinae (r = 0.77, P < 0.01) in subsets of volunteers. In 45 men and women who ranged from lean to obese (body mass index = 18.5 to 35.9 kg/m(2)), including 10 patients with Type 2 diabetes mellitus, reduced MA was associated with increased muscle fiber lipid content determined with histological oil red O staining (P = -0.43, P < 0. 01). In a subset of these volunteers (n = 19), triglyceride content in percutaneous biopsy specimens from vastus lateralis was also associated with MA (r = -0.58, P = 0.019). We conclude that the attenuation of skeletal muscle in vivo determined by CT is related to its lipid content and that this noninvasive method may provide additional information regarding the association between muscle composition and muscle function.

Adult↗
PubMed1999

Computed tomography-guided wire localization of pulmonary lesions before thoracoscopic resection: results in 101 cases.

The authors determine the success rate, safety, and potential complications of computed tomography-guided preoperative hookwire localization of small peripheral pulmonary nodules. One hundred one consecutive wire localizations with addition of methylene blue injection were performed in 94 patients immediately before thoracoscopic resection of small lung lesions. Sixty-two patients had a known primary malignancy, whereas 32 had an asymptomatic nodule. Eighty-eight patients underwent single lesion localization, five underwent double localization, and one underwent triple wire placement. Five patients had previously undergone percutaneous biopsy that was nondiagnostic. The nodule was within the first wedge biopsy of lung tissue in 95 of 97 specimens (98%). A second wedge and an open lobectomy were required in one patient each. Three additional biopsies were intraoperatively deferred after the histologic diagnosis was established after removal of another nodule. The procedure was terminated before wire placement in one patient who was unable to successfully hold his breath. The wire dislodged with the tip in the pleural space rather than in the lung parenchyma in 22 cases; however, methylene blue tattoo allowed localization in 13 of these (59%). In the other nine cases, extra portals, digital palpation, or expanded wedge resection was required. Complications included pneumothorax in 48 cases, moderate pleuritic pain in five cases, seven small intercostal hematomas, and a 7-mm wire fragment retained in one patient's lung along the suture line. No patient required a preoperative drain for treatment of pneumothorax. Wire dislodgement occurred in 6 of 52 (12%) cases without an initial pneumothorax and in 16 of 48 (33%) cases if a pneumothorax occurred. Wires dislodged less frequently if placed either directly into or through the nodule in 11 of 64 (17%) cases than if placed adjacent to the nodule in 11 of 36 (31%) cases. Average wire tip depth from the visceral pleura was significantly less when the wire dislodged (11 mm) than when the wire remained in place (25 mm). Wire localization of small peripheral pulmonary nodules is a safe and effective procedure to assist thoracoscopic sublobectomy resection.

Coloring Agents↗
PubMed1999

Effects of weight loss on regional fat distribution and insulin sensitivity in obesity.

Weight loss (WL) decreases regional depots of adipose tissue and improves insulin sensitivity, two parameters that correlate before WL. To examine the potential relation of WL-induced change in regional adiposity to improvement in insulin sensitivity, 32 obese sedentary women and men completed a 4-month WL program and had repeat determinations of body composition (dual-energy X-ray absorptiometry and computed tomography) and insulin sensitivity (euglycemic insulin infusion). There were 15 lean men and women who served as control subjects. VO2max was unaltered with WL (39.2 +/- 0.8 vs. 39.8 +/- 1.1 ml x fat-free mass [FFM](-1) x min(-1)). The WL intervention achieved significant decreases in weight (100.2 +/- 2.6 to 85.5 +/- 2.1 kg), BMI (34.3 +/- 0.6 to 29.3 +/- 0.6 kg/m2), total fat mass (FM) (36.9 +/- 1.5 to 26.1 +/- 1.3 kg), percent body fat (37.7 +/- 1.3 to 31.0 +/- 1.5%), and FFM (59.2 +/- 2.3 to 55.8 +/- 2.0 kg). Abdominal subcutaneous and visceral adipose tissue (SAT and VAT) were reduced (494 +/- 19 to 357 +/- 18 cm2 and 157 +/- 12 to 96 +/- 7 cm2, respectively). Cross-sectional area of low-density muscle (LDM) at the mid-thigh decreased from 67 +/- 5 to 55 +/- 4 cm2 after WL. Insulin sensitivity improved from 5.9 +/- 0.4 to 7.3 +/- 0.5 mg x FFM(-1) x min(-1) with WL. Rates of insulin-stimulated nonoxidative glucose disposal accounted for the majority of this improvement (3.00 +/- 0.3 to 4.3 +/- 0.4 mg x FFM(-1) x min(-1)). Serum leptin, triglycerides, cholesterol, and insulin all decreased after WL (P < 0.01). After WL, insulin sensitivity continued to correlate with generalized and regional adiposity but, with the exception of the percent decrease in VAT, the magnitude of improvement in insulin sensitivity was not predicted by the various changes in body composition. These interventional weight loss data underscore the potential importance of visceral adiposity in relation to insulin resistance and otherwise suggest that above a certain threshold of weight loss, improvement in insulin sensitivity does not bear a linear relationship to the magnitude of weight loss.

Abdomen↗
PubMed1998

Selection of subtle cases for observer-performance studies: the importance of knowing the true diagnosis.

RATIONALE AND OBJECTIVES: To assess the usefulness of classifying degree of difficulty in abnormality detection and to determine the effect of knowing the true diagnosis when selecting subtle images for observer-performance studies. MATERIALS AND METHODS: A total of 529 posteroanterior chest images that had been used in a multiabnormality, multireader observer-performance study were rated by three observers as to the difficulty of determining the presence or absence of each abnormality when the true diagnosis was known and when it was not known. Changes in image subtlety ratings were evaluated, and actual observer-performance results for the different groups of images grouped according to raters' classifications with and without availability of the true diagnosis were compared. RESULTS: The majority of negative cases (9,168 of 12,258, 74.8%) were rated as "easy" to determine. Substantial changes were made during the selection of the "subtle" case category when the truth was known compared with when the truth was not provided. These changes caused differences between typical and subtle cases in terms of observer performance. Combined ratings of case subtlety by agreement of multiple classifiers resulted in a well-ordered selection with decreasing observer performance as a function of subtlety ratings. CONCLUSION: Cases for observer-performance studies that stress the diagnostic system can be successfully selected in the multiple-disease setting by experienced readers and should be selected with the truth known to the raters. The degree of agreement by multiple raters can be used to refine subtlety ratings.

Diagnosis, Differential↗
PubMed1998

Sagittal diameter in comparison with single slice CT as a predictor of total visceral adipose tissue volume.

BACKGROUND: Abdominal obesity has an important biological and epidemiological relationship to disease. The gold standard for measurement of visceral adipose tissue (VAT) is assessment by computerized tomography (CT) or magnetic resonance imaging (MRI), but because of simplicity and ease in collection, anthropometric variables are a desirable alternative to estimate VAT. OBJECTIVE: To compare the abilities of a single slice CT scan through the L4-L5 interspace (L4-L5 VAT), sagittal diameter, and body mass index (BMI) to estimate total volume VAT. Total volume VAT (the gold standard) was measured by total abdominal CT scanning, with a mean of 42 CT slices per patient. Estimation of VAT in subjects of similar body size was emphasized. DESIGN: Retrospective study of subjects undergoing complete abdominal and pelvic CT scanning for clinical reasons. SUBJECTS: 40 subjects (20 men and 20 women) mean age 56.5y, with a balanced selection for BMI < 27 and > 27. RESULTS: In univariate regression models, L4-L5 VAT explained the largest proportion of the variance in total VAT (R2=0.87 [P<0.001]), though age (R2=0.11 [P=0.04]), BMI (R2=0.37 [P<0.001]), and sagittal diameter (R2=0.50 [P < 0.001]) were also statistically significantly related to total VAT. When limited to individuals with a BMI > or= 27 however, L4-L5 VAT explained a large proportion of the variance in total VAT (R2=0.87 [P < 0.001]) whereas sagittal diameter was only of borderline significance (R2=0.20 [P=0.06]), and BMI was not associated with total VAT (R2=0.04 [P=NS]). In multiple regression analyses, L4-L5 VAT area explained a large proportion of the variance (0.84-0.90), and once in the model, BMI, sagittal diameter, and age did not additionally contribute significantly to the explained variance in total VAT. CONCLUSIONS: Abdominal sagittal diameter is poorly correlated to total VAT for men and women with a BMI > 27. Within a 2 cm range of sagittal diameter, there is nearly a three-fold variability in total VAT.

Adipose Tissue↗
PubMed1998

Biliary tract carcinoma complicating primary sclerosing cholangitis: evaluation with CT, cholangiography, US, and MR imaging.

PURPOSE: To assess the value of computed tomography (CT), cholangiography, ultrasonography (US), and magnetic resonance (MR) imaging in the demonstration of biliary tract carcinoma complicating primary sclerosing cholangitis (PSC). MATERIALS AND METHODS: Thirty patients were studied who had PSC and biliary tract carcinoma. Twenty-six patients had cholangiocarcinoma, and four had gallbladder carcinoma. Sixty-four CT scans, 41 cholangiograms, 40 US studies, and seven MR studies were reviewed retrospectively for evidence of tumor and PSC. Imaging results were correlated with pathologic findings from whole liver specimens and biopsies. Presence of mass was rated as definite, probable, possible, or doubtful or absent. RESULTS: On CT scans, cholangiocarcinomas produced hypoattenuating masses in 17 of 23 cases, delayed contrast enhancement in six of 12, progressive biliary dilatation in five of 15, and thickened bile duct wall in two of 23. On cholangiograms, dominant strictures were present in 18 of 21 cases of cholangiocarcinoma; 13 were malignant, and five were benign. Cholangiocarcinoma formed polypoid bile duct masses in two of 21 cases. Biliary dilatation was caused by cholangiocarcinoma in 10 of 12 cases and by benign stricture in two. Gallbladder carcinomas demonstrated masses on CT scans, cholangiograms, and US images, and wall thickening on CT and US images. Overall, definite or probable tumor was demonstrated in 25 of 30 patients (83%). CONCLUSION: Most biliary tract carcinomas complicating PSC can be demonstrated on imaging studies.

Adult↗
PubMed1997

Subcutaneous abdominal fat and thigh muscle composition predict insulin sensitivity independently of visceral fat.

Whether visceral adipose tissue has a uniquely powerful association with insulin resistance or whether subcutaneous abdominal fat shares this link has generated controversy in the area of body composition and insulin sensitivity. An additional issue is the potential role of fat deposition within skeletal muscle and the relationship with insulin resistance. To address these matters, the current study was undertaken to measure body composition, aerobic fitness, and insulin sensitivity within a cohort of sedentary healthy men (n = 26) and women (n = 28). The subjects, who ranged from lean to obese (BMI 19.6-41.0 kg/m2), underwent dual energy X-ray absorptiometry (DEXA) to measure fat-free mass (FFM) and fat mass (FM), computed tomography to measure cross-sectional abdominal subcutaneous and visceral adipose tissue, and computed tomography (CT) of mid-thigh to measure muscle cross-sectional area, muscle attenuation, and subcutaneous fat. Insulin sensitivity was measured using the glucose clamp technique (40 mU.m-2.min-1), in conjunction with [3-3H]glucose isotope dilution. Maximal aerobic power (VO2max) was determined using an incremental cycling test. Insulin-stimulated glucose disposal (Rd) ranged from 3.03 to 16.83 mg.min-1.kg-1 FFM. Rd was negatively correlated with FM (r = -0.58), visceral fat (r = -0.52), subcutaneous abdominal fat (r = -0.61), and thigh fat (r = -0.38) and positively correlated with muscle attenuation (r = 0.48) and VO2max (r = 0.26, P < 0.05). In addition to manifesting the strongest simple correlation with insulin sensitivity, in stepwise multiple regression, subcutaneous abdominal fat retained significance after adjusting for visceral fat, while the converse was not found. Muscle attenuation contributed independent significance to multiple regression models of body composition and insulin sensitivity, and in analysis of obese subjects, muscle attenuation was the strongest single correlate of insulin resistance. In summary, as a component of central adiposity, subcutaneous abdominal fat has as strong an association with insulin resistance as visceral fat, and altered muscle composition, suggestive of increased fat content, is an important independent marker of insulin resistance in obesity.

Abdomen↗
PubMed1995

Percutaneous ultrasound-guided needle biopsy of hepatic mass lesions using a cytohistologic approach. Comparison of two needle types.

This study compared the ability to diagnose and accurately classify hepatic mass lesions by ultrasound-guided biopsy using two different needle types: a 20 gauge needle that yielded primarily cytologic material and an 18 gauge automated core biopsy needle. Slides prepared from each of the needle types were separately evaluated in a blinded fashion. The 20 gauge needle had a sensitivity of 90%, a specificity of 90%, and enabled exact tumor classification in 70% of cases. The 18 gauge core biopsy had a sensitivity of 85%, a specificity of 100%, and allowed exact tumor typing in 82% of cases. The sensitivity and specificity of both needle types combined was 98% and 100%, respectively, and all malignancies were correctly typed. A combined cytohistologic approach provides a highly accurate means of diagnosing and typing hepatic tumors and provides a suitable sample for confirmatory stains. Accurate tumor typing may affect therapeutic decisions.

Adult↗
PubMed1995

Skeletal muscle utilization of free fatty acids in women with visceral obesity.

Visceral obesity is strongly associated with insulin resistance. One potential cause is increased availability of FFA. Alternatively, it has been proposed that there is impaired oxidation of lipid in individuals at risk for obesity. The extent to which either concept involves skeletal muscle is uncertain. To examine these opposing hypotheses, 17 healthy lean and obese premenopausal women, among whom cross-sectional area of visceral fat ranged from 18 to 180 cm2, participated in leg balance studies for measurement of FFA and glucose utilization during basal and insulin-stimulated conditions. A metabolic profile of skeletal muscle, based on enzyme activity, was determined in vastus lateralis muscle obtained by percutaneous biopsy. Visceral fat content was negatively correlated with insulin sensitivity (rates of leg glucose uptake and storage), but insulin resistance was not caused by glucose-FFA competition. During hyperinsulinemia, neither leg FFA uptake nor oxidation was increased in women with visceral obesity. During fasting conditions, however, rates of FFA uptake across the leg were negatively correlated with visceral adiposity as were activities of muscle carnitine palmitoyl transferase and citrate synthase. In summary, visceral adiposity is clearly associated with skeletal muscle insulin resistance but this is not due to glucose-FFA substrate competition. Instead, women with visceral obesity have reduced postabsorptive FFA utilization by muscle.

Adult↗
PubMed1995

Skeletal muscle glycolytic and oxidative enzyme capacities are determinants of insulin sensitivity and muscle composition in obese women.

Regional fat distribution is an important determinant of insulin resistance in obesity. In the current study, the relationship between skeletal muscle insulin sensitivity, mid-thigh muscle composition, and the metabolic profile of muscle was investigated. Muscle composition was assessed by computed tomography of the mid-thigh, and by activities of marker enzymes of aerobic-oxidative and glycolytic pathways and muscle fiber typing using biopsies of the vastus lateralis muscle. Muscle with reduced Hounsfield attenuation on computed tomography scans was increased in proportion to obesity, and was strongly related to insulin resistance, reduced muscle oxidative capacity, and increased anaerobic and glycolytic capacities by muscle. These findings suggest that as part of its expression of insulin resistance, skeletal muscle of obese individuals is also poorly equipped for substrate oxidation and manifests increased storage of fat.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1995

Reproducibility of computed tomography measurement of visceral adipose tissue area.

OBJECTIVE: The purpose of the current study is to examine the reproducibility of CT measurement of the cross-sectional area of abdominal adipose tissue. DESIGN: Sixteen healthy pre-menopausal women, ranging from lean to obese, underwent duplicate cross-sectional CT scans of the abdomen at the level of the 4th lumbar vertebral disc space. Subjects stood after the initial scan and were then re-positioned prior to repeat CT scanning. RESULTS: There was a high degree of reproducibility in measurement of overall cross-sectional adipose tissue (AT) and in the partitioning of this into subcutaneous and visceral AT. The excellent reproducibility is demonstrated by a high correlation between duplicate measurements (r = 0.99, P < 0.01), and by small precision errors; 1.2% of the mean value for total AT cross-sectional area, 1.9% for subcutaneous AT area, and 3.9% for visceral AT area. CONCLUSION: Measurement of abdominal AT area by cross-sectional CT scanning is not only an accurate determination of this adipose depot but can also be repeated with a high degree of precision.

Adipose Tissue↗
PubMed1994

Subjective and objective assessment of image quality--a comparison.

Forced-choice just noticeable difference (JND) studies are extremely sensitive to image quality variations that are below the threshold at which the differences are apparent to or definable by the observer. Paired comparisons of 4K and 2K laser-printed posteroanterior chest images consistently demonstrated that although images are viewed as comparable by radiologists, when forced to choose the better ("sharper") image, they actually select the higher-resolution images in 83% of the paired observations. We conclude that small differences in image quality may be detectable even in image sets which are considered to be comparable by subjective assessments.

Differential Threshold↗