Protocol for measurement of liver fat by computed tomography.

To develop a protocol for measurement of liver fat using computed tomography (CT), we conducted a preliminary study with 118 men and 76 women to determine a readily identifiable vertebral landmark at which the CT image displayed both liver and spleen. Analysis of five landmarks revealed that the CT image obtained at the T12-L1 level simultaneously displayed the liver and spleen in 90% of the men and women. The T12-L1 protocol was cross-validated on a sample of 130 men and 113 women. In this sample, we also assessed the regional characteristics of liver and spleen tissue attenuation at the T12-L1 level by subdividing each image into quartiles from anterior to posterior, each of which were further divided into medial and lateral regions. A similar analysis was performed on images located 12 mm above and below T12-L1. The T12-L1 image displayed both liver and spleen in 92% (403 of 437) of the combined study sample. There was a significant (P<0.005) stepwise increase in attenuation values [Hounsfield units (HU)] from the inferior to superior image. Although some significant (P<0.05) differences were observed between the eight regions by comparison to the whole liver or spleen, the average magnitude of the difference was <2.0 HU for liver and <3.5 HU for spleen. Acquisition of a single CT image at the T12-L1 level is a practical and reliable method for routine measurement of liver fat in research and clinical settings.     

Segmentation and measurement of fat volumes in murine obesity models using X-ray computed tomography

Obesity is associated with increased morbidity and mortality as well as reduced metrics in quality of life. Both environmental and genetic factors are associated with obesity, though the precise underlying mechanisms that contribute to the disease are currently being delineated. Several small animal models of obesity have been developed and are employed in a variety of studies. A critical component to these experiments involves the collection of regional and/or total animal fat content data under varied conditions. Traditional experimental methods available for measuring fat content in small animal models of obesity include invasive (e.g. ex vivo measurement of fat deposits) and non-invasive (e.g. Dual Energy X-ray Absorptiometry (DEXA), or Magnetic Resonance (MR)) protocols, each of which presents relative trade-offs. Current invasive methods for measuring fat content may provide details for organ and region specific fat distribution, but sacrificing the subjects will preclude longitudinal assessments. Conversely, current non-invasive strategies provide limited details for organ and region specific fat distribution, but enable valuable longitudinal assessment. With the advent of dedicated small animal X-ray computed tomography (CT) systems and customized analytical procedures, both organ and region specific analysis of fat distribution and longitudinal profiling may be possible. Recent reports have validated the use of CT for in vivo longitudinal imaging of adiposity in living mice. Here we provide a modified method that allows for fat/total volume measurement, analysis and visualization utilizing the Carestream Molecular Imaging Albira CT system in conjunction with PMOD and Volview software packages.     

Indication for computed tomography of the brain in patients with first uncomplicated generalised seizure.

OBJECTIVES--To assess the yield of emergency computed tomography of the brain in patients with a first generalised epileptic seizure and to evaluate a four item screening questionnaire on alcohol misuse (CAGE questionnaire) as a triage tool to avoid unnecessary scans in cases of seizures related to withdrawal from alcohol. DESIGN--Prospective, observational. SETTING--Medical casualty unit in a university hospital. PATIENTS--119 adult patients presenting to casualty within one hour of a generalised seizure. MEASUREMENTS--A clinical examination focusing on focal neurological symptoms, the CAGE questionnaire, and computed tomography of the brain with contrast enhancement. RESULTS--Computed tomography showed a focal, structural lesion of the brain in 40 patients (34% (95% confidence interval 25% to 42%)). In 20 patients (17% (10% to 24%)) an important therapeutic intervention resulted. The presence of a focal neurological deficit had a sensitivity of 50% and a specificity of 89% in predicting focal lesions on computed tomography. Answering "yes" to fewer than two CAGE questions had a sensitivity of 90% and specificity of 44% in identifying patients with focal computed tomography lesions. Focal lesions were not detected on computed tomography in any of the 35 patients (0% (0% to 10%)) who showed no focal neurological symptoms and answered "yes" to two or more CAGE questions. CONCLUSIONS--The diagnostic yield of computed tomography of the brain in adults after a first generalised seizure is high. Combined with the clinical examination, the CAGE questionnaire can reliably identify patients with uncomplicated seizures related to withdrawal from alcohol, in whom computed tomography may not be absolutely necessary.     

Value of computed tomography in patients with stroke: Oxfordshire Community Stroke Project.

The usefulness of computed tomography (CT) was assessed in 325 consecutive patients with a "clinically definite first stroke" from a community stroke register. CT detected five "non-stroke" lesions (two cerebral gliomas, one cerebral metastasis, and two subdural haematomas), a frequency of 1.5%. Five patients were identified with cerebellar haemorrhage, but only one survived long enough to have a CT scan. CT was useful in excluding intracranial haemorrhage as the cause of the stroke in four patients receiving anticoagulants and seven receiving antiplatelet treatment; it showed intracranial haemorrhage in one patient taking aspirin. Forty six patients were in atrial fibrillation at the time of their stroke; four had intracranial haemorrhages and three had haemorrhagic cerebral infarcts. Nineteen patients with presumed ischaemic minor stroke were considered suitable for carotid endarterectomy; CT showed small haemorrhages in two. The CT scan provides very useful information in a minority (up to 28%) of patients with first stroke, who can be selected on quite simple criteria: (a) doubt (usually because of an inadequate history) whether the patient has stroke or a treatable intracranial lesion; (b) the possibility of cerebellar haemorrhage or infarction; (c) the exclusion of intracranial haemorrhage in patients who either are already taking or likely to need antihaemostatic drugs or are being considered for carotid endarterectomy; (d) if the patient deteriorates in a fashion atypical of stroke.     

Value of computed tomography of the abdomen and chest in investigation of Cushing's syndrome.

Computed tomography (CT) scans were performed on 37 patients with biochemically proved Cushing''s syndrome to evaluate the role of CT in the investigation of this condition. CT rapidly and correctly identified all 15 adrenocortical tumours, distinguishing five carcinomas from the 10 adenomas. In ACTH-dependent Cushing''s syndrome appreciable bilateral adrenal enlargement was common in patients with an ectopic source (6 of 10 cases), while those with a pituitary source usually had normal sized adrenals (9 of 10). Two patients with a history of over seven years had bilateral adrenal nodules. CT was more accurate in locating a primary ectopic source of ACTH (5 of 12 cases) than any other technique and was particularly valuable in detecting small (less than 1.5 cm) peripheral lung carcinoid tumours which may be undetectable by conventional x-ray techniques. Its speed, accuracy, and simplicity make CT the technique of choice both to show the adrenal anatomy and to locate a suspected ectopic ACTH-secreting tumour in patients with proved Cushing''s syndrome.     

The frequency of alternate muscle activity is associated with the attenuation in muscle fatigue.

Alternate muscle activity between synergist muscles has been demonstrated during low-level sustained contractions [< or =5% of maximal voluntary contraction (MVC) force]. To determine the functional significance of the alternate muscle activity, the association between the frequency of alternate muscle activity during a low-level sustained knee extension and the reduction in knee extension MVC force was studied. Forty-one healthy subjects performed a sustained knee extension at 2.5% MVC force for 1 h. Before and after the sustained knee extension, MVC force was measured. The surface electromyogram was recorded from the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) muscles. The frequency of alternate muscle activity for RF-VL, RF-VM, and VL-VM pairs was determined during the sustained contraction. The frequency of alternate muscle activity ranged from 4 to 11 times/h for RF-VL (7.0 +/- 2.0 times/h) and RF-VM (7.0 +/- 1.9 times/h) pairs, but it was only 0 to 2 times/h for the VL-VM pair (0.5 +/- 0.7 times/h). MVC force after the sustained contraction decreased by 14% (P < 0.01) from 573.6 +/- 145.2 N to 483.3 +/- 130.5 N. The amount of reduction in MVC force was negatively correlated with the frequency of alternate muscle activity for the RF-VL and RF-VM pairs (P < 0.001 and r = 0.65 for both) but not for the VL-VM pair. The results demonstrate that subjects with more frequent alternate muscle activity experience less muscle fatigue. We conclude that the alternate muscle activity between synergist muscles attenuates muscle fatigue.     

A congenic strain (F344.OLETF-Imfm) displays the existence of intramuscular fat accumulation QTL on rat chromosome 1.

A genomic region between D1Wox8 and D1Rat90 on rat chromosome 1 was previously shown to be linked to intramuscular fat accumulation by quantitative trait locus (QTL) analysis using a F2 population derived from the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, which exhibits an increase in the levels of intramuscular fat content in Musculus longissimus, and the F344 rat. There exist two regions showing major and minor lod peaks for linkage to intramuscular fat accumulation, in the chromosomal region. We constructed a congenic strain introgressing the OLETF allele on the minor but not the major lod peak region in the F344 rat strain. The congenic strain had higher levels of intramuscular fat content in Musculus longissimus than the inbred partner F344 rat, thereby proving the existence of a QTL, designated Imfm (for Intramuscular fat-minor), responsible for the intramuscular fat accumulation in the congenic region of the minor lod peak region of about 10 cM. The F344.OLETF-Imfm congenic strain might provide a refined tool for the analysis of the gene causing intramuscular fat accumulation.     

Increased intramyocellular lipid accumulation in HIV-infected women with fat redistribution.

The human immunodeficiency virus (HIV)-lipodystrophy syndrome is associated with fat redistribution and metabolic abnormalities, including insulin resistance. Increased intramyocellular lipid (IMCL) concentrations are thought to contribute to insulin resistance, being linked to metabolic and body composition variables. We examined 46 women: HIV infected with fat redistribution (n = 25), and age- and body mass index-matched HIV-negative controls (n = 21). IMCL was measured by 1H-magnetic resonance spectroscopy, and body composition was assessed with computed tomography, dual-energy X-ray absorptiometry (DEXA), and magnetic resonance imaging. Plasma lipid profile and markers of glucose homeostasis were obtained. IMCL was significantly increased in tibialis anterior [135.0 +/- 11.5 vs. 85.1 +/- 13.2 institutional units (IU); P = 0.007] and soleus [643.7 +/- 61.0 vs. 443.6 +/- 47.2 IU, P = 0.017] of HIV-infected subjects compared with controls. Among HIV-infected subjects, calf subcutaneous fat area (17.8 +/- 2.3 vs. 35.0 +/- 2.5 cm2, P < 0.0001) and extremity fat by DEXA (11.8 +/- 1.1 vs. 15.6 +/- 1.2 kg, P = 0.024) were reduced, whereas visceral abdominal fat (125.2 +/- 11.3 vs. 74.4 +/- 12.3 cm2, P = 0.004), triglycerides (131.1 +/- 11.0 vs. 66.3 +/- 12.3 mg/dl, P = 0.0003), and fasting insulin (10.8 +/- 0.9 vs. 7.0 +/- 0.9 microIU/ml, P = 0.004) were increased compared with control subjects. Triglycerides (r = 0.39, P = 0.05) and extremity fat as percentage of whole body fat by DEXA (r = -0.51, P = 0.01) correlated significantly with IMCL in the HIV but not the control group. Extremity fat (beta = -633.53, P = 0.03) remained significantly associated with IMCL among HIV-infected patients, controlling for visceral abdominal fat, abdominal subcutaneous fat, and antiretroviral medications in a regression model. These data demonstrate increased IMCL in HIV-infected women with a mixed lipodystrophy pattern, being most significantly associated with reduced extremity fat. Further studies are necessary to determine the relationship between extremity fat loss and increased IMCL in HIV-infected women.     

The role of perfusion computed tomography in the prediction of cerebral hyperperfusion syndrome

Background

Hyperperfusion syndrome (HPS) following carotid angioplasty with stenting (CAS) is associated with significant morbidity and mortality. At present, there are no reliable parameters to predict HPS. The aim of this study was to clarify whether perfusion computed tomography (CT) is a feasible and reliable tool in predicting HPS after CAS.

Methodology/Principal Findings

We performed a retrospective case-control study of 54 patients (11 HPS patients and 43 non-HPS) with unilateral severe stenosis of the carotid artery who underwent CAS. We compared the prevalence of vascular risk factors and perfusion CT parameters including regional cerebral blood volume (rCBV), regional cerebral blood flow (rCBF), and time to peak (TTP) within seven days prior to CAS. Demographic information, risk factors for atherosclerosis, and perfusion CT parameters were evaluated by multivariable logistic regression analysis. The rCBV index was calculated as [(ipsilateral rCBV - contralateral rCBV)/contralateral rCBV], and indices of rCBF and TTP were similarly calculated. We found that eleven patients had HPS, including five with intracranial hemorrhages (ICHs) of whom three died. After a comparison with non-HPS control subjects, independent predictors of HPS included the severity of ipsilateral carotid artery stenosis, 3-hour mean systolic blood pressure (3 h SBP) after CAS, pre-stenting rCBV index >0.15 and TTP index >0.22.

Conclusions/Significance

The combination of severe ipsilateral carotid stenosis, 3 h SBP after CAS, rCBV index and TTP index provides a potential screening tool for predicting HPS in patients with unilateral carotid stenosis receiving CAS. In addition, adequate management of post-stenting blood pressure is the most important treatable factor in preventing HPS in these high risk patients.     

Functional multislice spiral computed tomography of the rectus muscle of the eye in scar changes

The study deals with the capacities of functional multislice spiral computed tomography (FMSCT) in choosing a treatment policy and planning the tactic and scope of surgery for posttraumatic scar changes in the rectus muscle of the eye. Orbital MSCT and FMSCT were conducted in 15 patients (30 orbits). The findings showed that it was necessary to perform orbital FMSCT in posttaumatic scar changes to evaluate the contractility of the rectus muscles and their involvement in the area where a fracture occurs. Improved diagnosis achieved by FNSCT could optimally choose the tactics and scope of surgical intervention.     

The role of computed tomography in the diagnosis of brain involvement in patients with posttraumatic epilepsy]

Fifteen patients with posttraumatic epilepsy (10 men and 5 women aged 15 to 47) were examined in 1990-1991. All the patients had a history of craniocerebral injury (closed in 7 and open in 8 cases), 6 of them were operated on for intracranial hematomas. Besides CAT, electroencephalography, craniography, and examination of the fundus oculi were carried out. CAT was performed with a Ct MAX (General Electric) unit. Standard positioning of the patients with sectional projections parallel to the orbital meatal line was used. Changes in the brain matter were detected in 13 of these 15 patients: foreign bodies (2 cases), meningeal cerebral cicatrices (5), dilatation of the ventricular system (4), petrificates in the brain matter (1), atrophic changes of the cerebral cortex (1). The tomograms of two patients were normal. Ten patients were operated on: 2 were subjected to anterior callosotomy, in 2 foreign bodies were removed, and in 6 patients staged plasty with removal of the meningeal cerebral cicatrix was carried out. The detected CAT changes helped diagnose the topical location of the epileptogenic focus and choose the optimal method of surgery for posttraumatic epilepsy.     

In vivo evaluation of the effectiveness of bronchial thermoplasty with computed tomography.

A recent study has reported that the application of thermal energy delivered through a bronchoscope (bronchial thermoplasty) impairs the ability of airway smooth muscle to shorten in response to methacholine (MCh)(Danek CJ, Lombard CM, Dungworth DL, Cox PG, Miller JD, Biggs MJ, Keast TM, Loomas BE, Wizeman WJ, Hogg JC, and Leff AR. J Appl Physiol 97: 1946-1953, 2004). If such a technique is successful, it has the potential to serve as a therapy to attenuate airway narrowing in asthmatic subjects regardless of the initiating cause that stimulates the smooth muscle. In the present study, we have applied high-resolution computed tomography to accurately quantify the changes in airway area before and after a standard MCh aerosol challenge in airways treated with bronchial thermoplasty. We studied a total of 193 airways ranging from 2 to 15 mm in six dogs. These were divided into treated and control populations. The MCh dose-response curves in untreated airways and soon-to-be-treated airways were superimposable. In contrast, the dose-response curves in treated airways were shifted upward at all points, showing a significantly decreased sensitivity to MCh at both 2 and 4 wk posttreatment. These results thus show that treated airways have significantly increased luminal area at any dose of inhaled MCh compared with untreated airways. The work in this study thus supports the underlying concept that impairing the smooth muscle may be an effective treatment for asthma.     

Postprandial changes in the proteome are modulated by dietary fat in patients with metabolic syndrome

Metabolic syndrome is a multicomponent disorder whose etiology is the result of a complex interaction between genetic, metabolic and environmental factors including dietary habits. Our aim was to identify proteome–diet interactions during the postprandial state after the acute intake of four meals with different qualities of fat in the proteome of peripheral blood mononuclear cells. A randomized controlled trial conducted within the LIPGENE study assigned 39 metabolic syndrome patients to one of four meals: a high-saturated-fatty-acid (HSFA) meal, a high-monounsaturated-fatty-acid (HMUFA) meal and two high-polyunsaturated-fatty-acid (from walnut) (HPUFA) meals supplemented with n-3 PUFA or placebo. We analyzed the postprandial changes in the whole proteome of both nuclear and cytoplasmic fractions of peripheral blood mononuclear cells by two-dimensional proteomics. Twenty-three proteins were differentially expressed. HSFA intake caused the postprandial increase of proteins responding to oxidative stress (HSPA1A, PDIA3 and PSME1) and DNA damage (SMC6), whereas HMUFA intake led to the up-regulation of HSPA1A and PDIA3. HPUFA meal supplementation with n-3 PUFA produced peroxisomal beta-oxidation inhibition by down-regulation of ECH1, a process related to insulin signaling improvement. In conclusion, HSFA meal intake causes deleterious postprandial changes in the proteome in terms of DNA damage and procoagulant state, which reflect a higher postprandial oxidative stress after HSFA meal intake as compared to intake of HMUFA and HPUFA meals. Moreover, the addition of long-chain n-3 PUFA to an HPUFA meal may improve insulin signaling and exerts an anti-inflammatory effect when compared to an HPUFA meal.