Estimation of size-specific dose estimate (SSDE) of CT scans using an effective diameter electron density.

OBJECTIVE: An assessment of the effective diameter of a patient's body using electron densities of tissues inside the scan area (Deffρe) was proposed to overcome challenges associated with the estimation of water-equivalent diameter (Dw), which is used for size-specific dose estimate (SSDE). The aims of this study were to (1) investigate the Deffρe method in two different forms using a wide range of patient sizes and scanning protocols, and (2) compare between four methods used to estimate the patient size for SSDE. MATERIALS AND METHODS: Under IRB approval, a total of 350 patients of varying sizes have been collected retrospectively from the Hospital. The Dw values were assessed over six different CT body protocols: (1) chest with contrast media, (2) chest High-Resolution Computed Tomography (HRCT) without contrast media, (3) abdomen-pelvis with contrast media, (4) abdomen-pelvis without contrast media, (5) chest-abdomen-pelvis with contrast media, and (6) pelvis without contrast media. A MATLAB-based code was developed in-house to assess the size of each patient using the conventional effective diameter method (Deff), Deffρe by correcting either both the lateral (LAT) and anterior-posterior (AP) dimensions (Deff,LAT+APρe) or LAT only (Deff,LATρe), and Dw at the mid-CT slice of the patient images. RESULTS: The results of Deff,LAT+APρe and Deff,LATρe provided a better estimation for the chest protocols with the averages of absolute percentage difference (PD) values in the range of 3 - 7 % for all patient sizes as compared to the Dw method, whereas the averages of PD values for the Deff method were 9 - 15 %. However, Deff gave a better estimation for Dw values for the other body protocols, with differences of 2 - 4 %, which were lower than those obtained with the Deff,LAT+APρe and Deff,LATρe methods. For the chest protocols, statistically significant differences were found between Deff and the other methods, but there were no significant differences between all the methods for the other scanning protocols. The results show that the correction of both dimensions, LAT and AP, did not improve the accuracy of the Deffρe method, and, for most protocols, Deff,LAT+APρe gave larger range differences compared to those based on correction of the LAT dimension only. CONCLUSION: If the Dw cannot be assessed, the Deff,LATρe method may only be considered for the chest protocols as an alternative approach. The Deff method may also be used for all regions taking into account the application of a correction factor for the chest protocols to avoid a significant under or overestimation of the patient dose.

Prevalence of bacterial bloodstream infections and association between neutropenia and 30-day mortality among oncology inpatients at a university hospital in Saudi Arabia.

BACKGROUND: Cancer patients are highly prone to develop bacterial bloodstream infections (BSI) and are also at risk of neutropenia. Knowledge of the prevalence of these infections and whether neutropenia is associated with a change in mortality is important to more effective management and reducing mortality and morbidity. OBJECTIVES: Estimate the prevalence of bacterial BSI among oncology inpatients and assess the associations of 30-day mortality with Gram stain results and neutropenia. DESIGN: Retrospective cross-sectional SETTING: University hospital in Saudi Arabia. PATIENTS AND METHODS: We retrieved records of oncology inpatients at King Khalid University Hospital, excluding patients without malignancy and with non-bacterial BSI. The number of records included in the analysis was reduced based on a sample size calculation and systematic random sampling used to select patients to include in the study. MAIN OUTCOME MEASURES: Prevalence of bacterial BSI and association between neutropenia and 30-day mortality. SAMPLE SIZE: 423. RESULTS: The prevalence of bacterial bloodstream infections was 18.9% (n=80). Gram-negative bacteria were more prevalent (n=48, 60.0%) than gram-positive bacteria, with the most common being Escherichia coli (n=20, 25.0%). The 23 patients (28.8%) who died included 16 (69.6%) with gram-negative infections and 7 (30.4%) with gram-positive infections. There was no statistically significant association of bacterial BSI-related 30-day mortality with Gram stain (P=.32). Of 18 patients (22.5%) who were neutropenic, only one (5.6%) died. Sixty-two (77.5%) patients were non-neutropenic, of whom 22 (35.50%) died. We found a statistically significant association between the presence of neutropenia and bacterial BSI-related 30-day mortality (P=.016), with mortality being lower among neutropenic patients. CONCLUSIONS: Gram-negative bacteria are more prevalent in bacterial BSI than gram-positive bacteria. No statistically significant association of Gram stain result with mortality was found. However, the 30-day mortality rate was lower among neutropenic patients than among non-neutropenic patients. We recommend further investigation with a larger sample size in multiple regions to further unravel the association of neutropenia with bacterial bloodstream infection-related 30-day mortality. LIMITATIONS: Lack of regional data and sample size. CONFLICT OF INTEREST: None.

The Diagnostic Yield of Abdominal Ultrasounds Requested by Family Physicians at an Academic Hospital in Riyadh, Saudi Arabia.

BACKGROUND: Abdominal ultrasound is a non-invasive, relatively inexpensive, and widely available diagnostic modality in family medicine settings. OBJECTIVES: Our study aimed to identify the most common indications for requesting abdominal ultrasounds by family physicians, determine the frequency of abdominal ultrasound with abnormal findings, identify the most common findings, and determine patients' characteristics associated with abnormal findings. METHODS: This retrospective chart-based study was conducted from January 2020 to June 2020 to analyze patients' abdominal ultrasounds reports requested by family physicians in 2019 at King Khalid University Hospital (KKUH), Riyadh, Saudi Arabia. RESULTS: We assessed abdominal ultrasound reports of 1,113 patients. There were 620 (55.7%) female patients. The mean age and body mass index (BMI) were 46.35 years ± 15.04 and 29.33 kg/m2 ± 7.06, respectively. The most common indications were abdominal pain (43.2%), suspicion of gallbladder and biliary system diseases (18.5%), and abnormal liver function tests (14.6%). The frequency of abnormal findings was 793 (71.2%), and the most common findings were fatty liver infiltration (49.7%), liver enlargement (20.1%), and gallstones (13.3%). Females had a lower likelihood to have abnormal findings compared to males (odds ratio (OR)=0.688, p=0.009). Lastly, the likelihood of abnormal findings increased with age and was highest among patients aged 71 years or more (OR=25.9, p< 0.001). CONCLUSION: Abnormal findings were more prevalent in our study compared with other studies. Abnormal findings were more common among males and older age groups. We recommend future studies on patients from community-based family medicine settings, and to examine the association of abnormal findings with patient-centered endpoints. Finally, disseminating the results of this study will inform family physicians with the most common abnormal abdominal ultrasound findings, and will enhance the discussion with patients undergoing an abdominal ultrasound examination.

To What Extent the Emergency Physicians in Riyadh City Are Aware of Patient Radiation Exposure From Diagnostic Imaging Requested in the Emergency Department.

Introduction Radiological imaging that uses ionizing radiation in emergency departments (EDs) has increased with advances in radiological diagnostic methods. Emergency (ER) physicians' awareness of the radiation doses and the associated cancer risks that the patients are exposed to was surveyed using a questionnaire. Aims To assess the ER physicians' awareness of radiation doses associated with the diagnostic imaging and to describe their practice about discussing radiation risk with patients at different hospitals in Riyadh city, Saudi Arabia. Methods A prospective, questionnaire-based observational study was conducted in 2016 among 176 ER physicians at different hospitals in Riyadh city. The percentage knowledge score and the frequency of discussing radiation risk with patients based on responses to three scenarios were rated on a visual analog scale (VAS), where a score of 100 indicated that physicians would always discuss it. Results The overall mean knowledge score was 28% (95% CI: 22-34). None of the studied parameters (gender, experience, country of medical qualification, type of degree, and employment level) showed a significant correlation with the overall awareness of ED physicians about radiation exposure. Over three-quarters of physicians (77%) underestimated the lifetime risk of fatal cancer attributed to a single computed tomography (CT) scan of the abdomen. Majority of physicians (60%) reported never discussing radiation risk with patients. The frequency at which physicians were discussing radiation risk with patients varied greatly depending on the clinical scenario (mean VAS scores between 46 and 82). Conclusions ER physicians of different hospitals in Riyadh city had a varied knowledge about the radiation exposure risks, although overall the perception was inadequate. The physicians should receive education, and the diagnostic imaging request may need to include information on radiation doses and risks.

Value of 18F-FET PET in adult brainstem glioma.

PURPOSE: To investigate 18F-fluoro-ethyl-tyrosine positron emission tomography (FET-PET) imaging characteristics of adult brainstem glioma (BSG). MATERIALS AND METHODS: FET-PET imaging and progression-free survival (PFS) of 16 adult patients with BSG was analyzed (9 high-grade gliomas, 7 low-grade gliomas). SUVmax, TBR, and time activity curves of FET-PET were calculated. RESULTS: Progressive gliomas had higher SUVmax (3.57 ±â€¯1.47 vs. 1.60 ±â€¯0.51; p = 0.003) and TBRmax (3.00 ±â€¯1.12 vs. 1.36 ±â€¯0.33; p = 0.001) than stable gliomas. Kaplan-Meier analysis showed longer PFS of tumors with TBRmax < 2.0 compared to tumors with TBRmax > 2.0 (665 ±â€¯32 days versus 220 ±â€¯39 days; p < 0.001). CONCLUSION: FET-PET uptake might be associated with disease progression in adult BSG.