Prospective dose monitoring using a manual dose management system: experience in brain computed tomography from a tertiary hospital in Nigeria.

A manual radiation dose management system was developed to track the radiation dose and scan parameters of patients for brain computed tomography (CT). Radiation dose in volume computed tomography dose index (CTDIvol) and dose length product (DLP) were monitored to identify procedures that may require optimisation using notification values. The data were analysed and compared with national and international diagnostic reference levels (DRLs). A total of 596 brain CTs were monitored and grouped as <1: 36, 1-<5: 38, 5-<10: 25, 10-<15: 31 and adult: 466. The CTDIvol notification value identified the following number of examinations having high CTDIvol in <1 y: 1, 1-<5: 1, 5-<10: 0, 10-<15: 0 and adult (>15): 11. Furthermore, the DLP notification values identified the following examinations with high DLP in <1 y: 1, 1-<5:1, 5-<10:1, 10-<15: 1 and adults (>15): 18. The established local paediatric DLP DRLs were 2-3 times higher than the international paediatric DLP DRLs. This calls for a total protocol review and optimisation considering the local CT practices for paediatric imaging.

RADIATION DOSE MANAGEMENT SYSTEM IN COMPUTED TOMOGRAPHY PROCEDURES: A SYSTEMATIC REVIEW.

A systematic literature review was carried out to explore articles that reported the use of radiation dose management systems (RDMSs) in computed tomography (CT). The preferred reporting items for systematic review and meta-analysis flow chart were used to screen articles in PubMed, EBSCOhost, Web of Science, SCOPUS and Cochrane Library. A total of 1041 articles were retrieved and screened. After evaluation against criteria, 38 articles were selected and synthesised narratively. The results revealed that several RDMSs have been used in CT. The review also indicated that the use of RDMSs has promoted the implementation of diagnostic reference levels for dose optimisation. A RDMS, such as DoseWatch, is associated with compatibility challenges and failure in data transmission, while manual RDMSs are cumbersome and prone to data entry errors. Thus, a robust automated RDMS that is compatible with the different CT systems would provide efficient CT dose management.

Chronic Kidney Disease Modifies The Relationship Between Body Fat Distribution and Blood Pressure: A Cross-Sectional Analysis.

INTRODUCTION: Measures of adiposity are related to cardiovascular disease risk, but this relationship is inconsistent in disease states, such as chronic kidney disease (CKD). This study investigated the relationship between adiposity and blood pressure (BP) by CKD status. MATERIALS AND METHODS: South Africans of mixed-ancestry (n=1,621) were included. Estimated glomerular filtration rate (eGFR) was based on the modification of diet in renal disease (MDRD) equation, and CKD defined as eGFR <60mL/min/1.73m2. Body fat distribution was assessed using anthropometry [body mass index (BMI) and waist circumference (WC)] and dual-energy x-ray absorptiometry (DXA) (n=152). Pulse pressure (PP) and mean arterial pressure (MAP) were calculated from systolic blood pressure (SBP) and diastolic blood pressure (DBP). RESULTS: In participants without CKD, anthropometric and DXA-derived measures positively correlated with SBP, DBP, MAP and PP (p<0.02 for all), except for leg fat mass (LFM), which was not associated with BP indices (p>0.100 for all). Contrary, in prevalent CKD (6%, n=96), only BMI was inversely associated with PP (p=0.0349). In multivariable analysis, only BMI and WC remained independently associated with SBP, DBP and MAP in the overall sample. Notably, the association between BMI, WC and LFM with SBP and PP, differed by CKD status (interaction: p<0.100 for all), such that only BMI and WC were associated with SBP in those without CKD and inversely associated with PP in those with CKD. LFM was inversely associated with SBP and PP in those with CKD. CONCLUSION: In people without CKD, BP generally increases with increasing measures of adiposity. However, excess body fat has a seemingly protective or neutral effect on BP in people with CKD.

Comparison of single-slice CT and DXA-derived measures of central adiposity in South African women.

BACKGROUND: Visceral adipose tissue (VAT) accumulation is a known risk factor for cardiometabolic diseases. Efficient imaging modalities are necessary to quantify VAT. The study assessed the agreement between dual-energy x-ray absorptiometry (DXA) and single-slice computed tomography (CT) for abdominal fat quantification in mixed-ancestry South African women, and determined if this differed by body mass index (BMI) categories. METHODS: VAT and abdominal subcutaneous adipose tissue (SAT) were measured using single-slice CT and DXA in 132 women aged 55 (45-64) years. Participants were categorised as normal weight (BMI < 25 kg/m2), overweight (BMI: 25-29.9 kg/m2) and obese (BMI ≥ 30 kg/m2). Pearson correlation coefficients and Bland-Altman analysis were used to determine agreement between the two measurements. RESULTS: Two thirds of the participants were obese. DXA and CT-derived measurements of abdominal VAT and SAT were significantly correlated in the overall sample (r = 0.872 and r = 0.966, both p < 0.001, respectively) and within BMI categories. DXA overestimated VAT and SAT in the overall sample and across BMI categories. In the overall sample, the mean difference (DXA-CT estimates) was 75.3 cm2 (95% CI: 68.8-81.8 cm2, p ≤ 0.0001) for VAT and 54.7 cm2 (47.1-62.3 cm2, p ≤ 0.0001) for SAT. Within increasing BMI categories, the variance between the two modalities was fixed for VAT (p = 0.359 for obese), whereas the variance for SAT was heteroscedastic (p ≤ 0.0001). CONCLUSIONS: DXA overestimated VAT and abdominal SAT in a sample of middle-aged mixed-ancestry South African women. VAT variance was fixed in the obesity category, an indication that DXA may be valid in measuring VAT in obese people.

The discriminatory power of visceral adipose tissue area vs anthropometric measures as a diagnostic marker for metabolic syndrome in South African women.

BACKGROUND: A number of studies have shown central adiposity, in particular visceral adipose tissue (VAT) accumulation to be a hallmark of metabolic syndrome (MetS). In clinical practice, waist circumference (WC) is used as a proxy for VAT. AIM: To compare the ability of dual energy x-ray absorptiometry (DXA)-derived VAT area and anthropometric measures of adiposity for diagnosing MetS in a sample of high risk South African women. METHODS: MetS was quantified using the Joint Interim Statement (JIS) criteria. Fasting glucose, insulin and lipid profile were measured in 204 post-menopausal women. Anthropometry measures included body mass index (BMI), WC, waist-to-hip ratio (WHR), waist-to-height ratio (WHtR) and a body shape index (ABSI). The area under the curve (AUC) was used to assess their performance in detecting any two components of MetS (excluding WC). Optimal WC and VAT area cut-points were derived to compare their performance for diagnosing MetS and to compare to internationally recognised cut-points. RESULTS: The highest AUC for the prediction of MetS was recorded for VAT, followed by WHtR and WC (AUC, 0.767, 0.747 and 0.738 respectively), but these did not differ significantly (all p ≥ 0.192). In contrast, VAT was significantly better than BMI (p = 0.028), hip (p = 0.0004) and ABSI (p < 0.0001). The optimal WC (94.4 cm) and VAT area (174 cm2 based on the Youden's index method and 175.50 cm2 based on the CTL approach) cut-points performed similarly in detecting MetS. CONCLUSION: DXA-derived VAT and WC had the same overall performance in discriminating the presence of any 2 MetS components in high risk South African women. These findings support the current recommendations of using WC rather than VAT for MetS risk screening, as it is cheap, accessible and easy to measure.

Associations between body fat distribution and cardiometabolic risk factors in mixed-ancestry South African women and men.

OBJECTIVE: To investigate the relationship between body fat distribution and cardiometabolic risk in mixed-ancestry South African (SA) men and women, and to explore the effect of menopausal status on these relationships in women. METHODS: In a cross-sectional study, 207 mixed-ancestry SA women and 46 men underwent measurement of body composition using dual-energy X-ray absorptiometry, blood pressure, oral glucose tolerance, lipid profile and high-sensitivity C-reactive protein determination. The associations between different body fat compartments and associated cardiometabolic risk factors were explored. RESULTS: Men had less percentage fat mass ( %FM) [26.5% (25-75th percentiles: 19.9-32.5) vs 44.0%(39.8-48.6), p ≤ 0.001], but more central and less peripheral fat (both p <0.001) than women. Post-menopausal women had greater %FM, waist and visceral adipose tissue (VAT), and less gynoid %FM than pre-menopausal women (all p ≤ 0.004). After adjusting for age and gender, VAT accounted for the greatest variance in insulin resistance (R2 = 0.27), while trunk %FM and leg %FM accounted for the greatest variance in triglyceride (R2 = 0.13) and high-density lipoprotein cholesterol concentrations (R2 = 0.14). The association between fat mass and regional subcutaneous adipose tissue and cardiometabolic risk factors differed by gender and menopausal status. CONCLUSIONS: Central fat was the most significant correlate of cardiometabolic risk and lower body fat was associated with reduced risk. These relationships were influenced by gender and menopausal status.