Standard-dose and 50%-reduced-dose chest CT: comparing the effect on image quality

OBJECTIVE: CT accounts for considerable population-based radiation dose from radiographic diagnostic studies. The technical factors for CT examinations are not appropriately adjusted on the basis of patient size and anatomy. We hypothesized that radiation doses for routine chest CT can be reduced by 50% for the evaluation of normal structures without seriously jeopardizing image quality. SUBJECTS AND METHODS: After receiving institutional review board approval, we prospectively studied 24 patients with cancer who were 65 years old and older on a multidetector CT scanner. Each patient underwent imaging with four slices (centered at the carina) at the standard dose (220-280 mAs) and at 50%-reduced dose (110-140 mAs) at a constant 140 kVp. Single breath-hold scanning was performed with a 2.5-mm detector configuration, a tube rotation time of 0.8 sec, and a pitch of 6:1. Contiguous images were reconstructed at 5-mm intervals. Two subspecialty-trained chest radiologists who were unaware of the CT technique reviewed randomized images for overall image quality and anatomic detail of the structures in the lung, airway, mediastinum, and chest wall using a 5-point scale (1, worst; 2, suboptimal; 3, adequate; 4, very good; 5, excellent). The data were analyzed using the Wilcoxon's signed rank test. RESULTS: Although overall image quality was better with standard-dose CT, the quality of reduced-dose CT was acceptable. The differences in mean scores were statistically significant. There was a correlation of 0.59 between observers. The mean scores of standard-dose CT were always greater than or equivalent to those of low-dose CT for both observers. The assessment of great vessels and soft tissue of the chest wall contributed mainly to the differences in image quality. Both the central and peripheral lung parenchyma and the airway were adequately visualized on low-dose CT. Radiation doses (based on weighted-CT-dose index) from standard-dose CT and 50%-reduced-dose CT were 15.6-21.4 mSv and 7.8-10.7 mSv, respectively (from the manufacturer's data). CONCLUSION: Chest CT image quality appears to be acceptable for evaluating normal anatomic structures even with a 50% reduction in radiation dose.     

Panfungal PCR Assay for Detection of Fungal Infection in Human Blood Specimens

A novel panfungal PCR assay which detects the small-subunit rRNA gene sequence of the two major fungal organism groups was used to test whole-blood specimens obtained from a series of blood or bone marrow transplant recipients. The 580-bp PCR product was identified after amplification by panfungal primers and hybridization to a 245-bp digoxigenin-labeled probe. The lower limit of detection of the assay was approximately four organisms per milliliter of blood. Multiple whole-blood specimens from five patients without fungal infection or colonization had negative PCR results. Specimens from 11 infected patients had positive PCR results. Blood from three patients with pulmonary aspergillosis had positive PCR results: one patient’s blood specimen obtained in the week prior to the diagnosis of infection by a positive bronchoalveolar lavage fluid culture result was positive by PCR, and blood specimens obtained from two patients 1 to 2 days after lung biopsy and which were sterile by culture were positive by PCR. The blood of four patients with candidemia, three patients with mixed fungal infections, and one patient with fusariosis also had positive PCR signals. The panfungal PCR assay can detect multiple fungal genera and may be used as an adjunct to conventional methods for the detection of fungal infection or for describing the natural history of fungal infection. Further studies are needed to define the sensitivity and specificity of this assay for the diagnosis of fungal infection prior to the existence of other clinical or laboratory indications of invasive fungal infection.     

Detection of Atopobium vaginae in postmenopausal women by cultivation-independent methods warrants further investigation

We sequenced 16S rRNA genes from the vaginal swab contents of a postmenopausal woman with asymptomatic bacterial vaginosis (BV). Sequences from Atopobium vaginae were the most commonly detected. In a survey of 35 other postmenopausal women, this organism was detected in 44% with BV but not in any subjects deemed healthy.     

Spinal Cord Injury Rehabilitation Evidence: Methods of the SCIRE Systematic Review

The Spinal Cord Injury Rehabilitation Evidence (SCIRE) is a synthesis of the research evidence underlying rehabilitation interventions to improve the health of people living with SCI. SCIRE covers a comprehensive set of topics and in this issue we present six papers relevant to SCI rehabilitation clinicians (SCI inpatient rehabilitation practices, gait strategies, upper extremity reconstructive surgery, spasticity treatments, cardiovascular health and bone health). The SCIRE used a systematic and well-defined protocol to assess and synthesize the evidence. Each article was scored for its methodological quality using either the Physiotherapy Evidence Database (PEDro) Score for randomized controlled trials or the Downs and Black Tool for other types of studies. Following the individual study assessment, conclusions were drawn about the accumulated studies for each topic of interest based on the levels of evidence, quality of studies and concurring evidence. The SCIRE project was designed for health professionals to inform them of best practices.     

Hyperhomocysteinemia and B-vitamin status after discontinuation of oral anticoagulation therapy in patients with a history of venous thromboembolism.

Although hyperhomocysteinemia is an established risk factor for venous thromboembolism there is no consensus for routine determination of circulating homocysteine in the UK, either at the beginning or end of oral anticoagulation therapy. The purpose of this study was to evaluate the prevalence of hyperhomocysteinemia and its relationship to folate and vitamin B12 status in subjects with venous thromboembolism 4 weeks after discontinuation of warfarin therapy. In 78 consecutively recruited patients, plasma homocysteine was significantly higher (p < 0.001) and red cell folate significantly lower (p = 0.03) than in controls. Plasma vitamin B12 was similar in both groups. Strikingly, 38.5% of patients had hyperhomocysteinemia (> 15 micromol/l). Retrospective analysis revealed a significant positive association between plasma total homocysteine and duration of warfarin therapy (p < 0.001) but a negative, though non-significant (p = 0.06), trend with warfarin dose. The results do not suggest any direct interaction between warfarin and plasma homocysteine but raise the possibility of reduced intake of a common food source of folate and vitamin K. One possibility is the shortage of green-leafy vegetables since patients are often advised to limit their intake of this major source of vitamin K. On the basis of this study we suggest that homocysteine screening should be carried out at the time that patients begin warfarin therapy.     

Relationship between diet-induced changes in body fat and appetite sensations in women

To quantify the impact of weight/fat loss on appetite sensations, 54 overweight women followed a caloric restriction program (−2900 kJ/day). Their body composition and appetite sensations were assessed. Visual analogue scales (VAS) were used to measure desire to eat, hunger, fullness and prospective food consumption. The results showed that there is a significant association between the decrease in body fat mass and the change in appetite sensations, predicting a 5.8-mm increase in desire to eat and a 3.6-mm decrease in fullness per kg fat loss. This quantified relationship could serve as a reference point to evaluate the satiating efficiency of functional foods when they are combined with a weight-reducing program.     

The Effects of Systemic Hypoxia on Colon Anastomotic Healing: An Animal Model

PURPOSE Acute postoperative systemic hypoxia occurs frequently in the clinical setting following intestinal resection, as a result of complications such as pneumonia, pulmonary edema, or the acute respiratory distress syndrome. Although it is well established that oxygen is essential for metabolism in general and intestinal anastomotic healing, the mechanisms by which systemic hypoxia affect this process are not clear. The purpose of this study was to establish an animal model to simulate acute systemic hypoxia and to examine the effects on anastomotic healing. We investigated the hypothesis that systemic hypoxia impairs anastomotic healing in the colon by disrupting revascularization via changes in the expression of two putative angiogenic factors: inducible nitric oxide synthase and vascular endothelial growth factor.METHODS Phase I: Juvenile male Sprague–Dawley rats underwent carotid artery cannulation. In a controlled environment the FiO₂ was incrementally decreased from 21 to 9 percent and the resultant PaO₂ measured. Phase II: Animals underwent colonic transection with immediate reanastomosis and were placed in either a normoxic (FiO₂ 21 percent) or hypoxic (FiO₂ 11 percent) environment for seven days. Perianastomotic in vivo tissue oxygen saturation was measured before segmental colon resection in each of the animals and at seven days before measurement of anastomotic bursting pressure. Perianastomotic tissue samples were assessed by Western blot assay for the expression of vascular endothelial growth factor and inducible nitric oxide synthase protein. Sections from each tissue sample were taken and evaluated by a pathologist blinded to treatment group for determination of anastomotic healing score.RESULTS Phase I: Incrementally decreasing the FiO₂ resulted in a progressive decrease in PaO₂ (r ² = 0.77). Phase II: Animals maintained in a hypoxic environment had a significant decrease in tissue oxygen saturation (73 ± 9 percent vs. 94 ± 3 percent; P < 0.0001) and anastomotic bursting pressure (118 ± 18 mmHg vs. 207 ± 30 mmHg; P < 0.0001) compared with normoxic controls. Systemic hypoxia induced a significant increase, when compared with normoxic controls, in vascular endothelial growth factor (247.1 ± 9.5 vs. 142.2 ± 10.6; P < 0.0001) and inducible nitric oxide synthase (259.6 ± 21.1 vs. 120.2 ± 10.9; P < 0.0001) protein expression and led to a significant decrease in the overall wound-healing score.CONCLUSION This study validates a new animal model to study the effects of acute systemic hypoxia on colonic anastomotic healing. In this model, systemic hypoxia directly translated into local tissue hypoxia, and anastomotic healing was impaired. Contrary to our original hypothesis, hypoxia led to a significant increase in vascular endothelial growth factor and inducible nitric oxide synthase protein expression at the colonic anastomotic site. Impairment in anastomotic integrity despite upregulation of these angiogenic factors could be a result of the inability of wounded tissue to respond to vascular endothelial growth factor and inducible nitric oxide synthase or alternatively, hypoxia may adversely affect collagen synthesis and deposition directly.Supported by Alberta Children’s Hospital Research Foundation.Presented in part at the meeting of The American Society of Colon and Rectal Surgeons in New Orleans, Louisiana, June 21 to 26, 2003.Reprint requests to: David L. Sigalet, M.D., Ph.D., FRCSC, Department of Surgery, Room 1746, Health Sciences Centre, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 2T9.     

The potential effectiveness of warning labels on cigarette packages: the perceptions of young adult Canadians

BACKGROUND: Since 1989 when health warning labels appeared on Canadian cigarette packages, the labels have changed from text only covering less than one quarter of the package to text and graphics covering over half the package. This study examines how Canadians in their 20s feel about the current graphic warning labels and their potential to prevent smoking and encourage quitting. METHODS: Participants between 20 and 24 years of age were part of a 10-year cohort study begun when the group was in Grade 6, with the purpose of examining factors that may affect smoking. Five questions about warning labels were added to the 2002 questionnaire requesting information on perceptions of the labels and their potential impact on smoking behaviours of young adults. One item had been included in previous questionnaires. RESULTS: 32.8% (n = 1267) of the respondents were smokers, with males (35.6%) being more likely to smoke than females (30.4%). Current smokers were less likely than experimental/ex-smokers to believe that warning labels with stronger messages would make people their age less likely to smoke. Female current smokers were more likely to think about quitting. CONCLUSION: Despite the efforts taken in developing the labels, some young adults are skeptical about their effects. Warning labels may have to be modified to target issues that are relevant to young adults; gender differences are important in this modification. Warning labels can offer an additional component to a comprehensive tobacco control program, in that they provide health information.