Dual-energy X-ray Absorptiometry Unit Research Articles

Quantifying misdiagnosis rates from cross-calibration biases and precision errors in dual-energy X-ray absorptiometry of the femoral neck.

Dual-energy X-ray absorptiometry (DXA) is an exam that measures areal bone mineral density (aBMD) and is regularly used to diagnose and monitor osteoporosis. Except for exam quality issues such as operator error, the quantitative results of an exam are not modified by a radiologist or other physician. DXA cross-calibration errors can shift diagnoses, conceivably leading to alternate intervention decisions and patient outcomes. After identifying and correcting a cross-calibration bias of 3.8% in our two DXA scanners' aBMD measurements, we investigated misdiagnosis rates for given cross-calibration errors in a single patient cohort to determine the impact on patient care and the value of cross-calibration quality control. The studied cohort was 8012 patients of all ages and sexes with femoral neck exams that were scanned on a single DXA unit from October 1, 2018 to March 31, 2021. There were six subcohorts delineated by age and sex, three female groups and three male groups. Data reporting focused on the highest risk subcohort of 2840 females aged 65 or older. The DXA unit had no calibration changes during that time. Only one femoral neck-left or right-was randomly chosen for analysis. Patients with multiple qualifying exams within the time interval had one exam randomly chosen. The proof-of-principle simulation shifted the aBMD values within a range of ±10%, ±8%, ±6%, ±4%, ±3.5%, ±3%, ±2.5%, ±2%, ±1.5%, ±1%, ±0.5%, and 0 (no shift); the cross-calibration shifts were informed by published results and institutional experience. Measurement precision was modeled by randomly sampling a Gaussian distribution characterized by the worst acceptable least significant change (LSC) of 6.9%, with 100000 samplings for each patient. T-scores were recalculated from the shifted aBMD values, followed by reassigned diagnoses from the World Health Organization's T-score-based scheme. The unshifted original subcohort of women aged 65 and older had 599 normal diagnoses (21.1% of the cohort), 1784 osteopenia diagnoses (62.8%), and 455 osteoporosis diagnoses (16.1%). Osteoporosis diagnosis rates were highly sensitive to aBMD shifts. At the extrema, a -10% aBMD shift led to +161% osteoporosis cases, and a +10% aBMD shift led to -64.5% osteoporosis cases. Within the more plausible ±4% aBMD error range, the osteoporosis diagnosis rate changed -10.5% per +1% aBMD shift as indicated by linear regression (R2 =0.98). Except for the men aged 49 years and younger subcohort, the total cohort and five subcohorts had fit line slopes ranging between -9.7% and -12.1% with R2 ≥ 0.98. Cross-calibration bias had greater influence for diagnosis count rates compared to measurement precision, that is, LSC. These results quantify the degree of misdiagnosis that can occur in a clinically relevant cohort due to cross-calibration bias. In medical practices where patients may be scanned on more than one DXA unit, ensuring cross-calibration quality is a critical and high-value quality control task with direct impact on patient diagnosis and treatment course. The clinical impact and incidence of poor DXA quality control practices, and cross-calibration in particular, should be studied further.

Association Between Costo-iliac Distance /Arm Span Ratio and Lumber Height and its Relation with Osteoporosis in a Group of Egyption Post-menopausal Women

AbstractBackground: Osteoporosis is a common condition, especially affecting the older female population. The ability to predict loss of lumbar height using simple anatomical measurements would be a useful tool.Aim: To examine the relationship between CID/AS ratio and spinal height. And if there was a correlation between CID/AS ratio and early osteoporosis..Methods: A case-control study was designed, 50 post-menopausal women as cases and 50 as controls aged 50-70 were recruited who attending DEXA unit, Eldemerdash hospital, Ain Shams University during the period between June 2016 to Marsh 2017. Arm span (AS) and the costo-iliac distance (CID) was measured as the number of cm between the costal margin and the pelvic ridge of a patient, measured in the midaxillary line, the CID/AS ratio was calculated. The L1–L4 vertebral height of each patient was obtained from dual-energy X-ray absorptiometry (DEXA).Results: The age of the studied cases, mean age 59.65 and SD 5.25. While the age of studied controls, mean age 57.67 and SD 5.48 (P value 0.07), the study was showed that no significant association between CID/AS ratio and lumber vertebral height, but there was a statistically correlation between CID/AS ratio and DEXA results (T score) with best cut off value CID/AS ratio > 0.058, Sensitivity = 74% Specificity = 60%Conclusions: The CID/AS ratio is a useful bedside test in identifying patients with osteoporosis.

Electronic Medical Record Integration for Streamlined DXA Reporting.

Dual-energy X-ray absorptiometry (DXA) is the most frequently performed examination to assess bone mineral density in clinical practice. Aside from images and graphical displays, many numerical values are part of DXA reports. These values are typically manually entered into the formal report through the electronic medical record or PACS workstation. The process takes time and is prone to errors. Exporting the DXA numerical data via HL7 engine to the electronic medical record was proposed to improve reporting efficiency and accuracy. The output from the DXA unit computer was reconfigured to export the report content via the HL7 interface engine into the electronic medical record. Radiology interpretive reporting was subsequently done directly in the electronic medical record. In the evaluation of errors, 100 preliminary DXA reports before the change and 100 after the change were examined. These reports were analyzed for errors that included decimal change, number transposition, negative number issue, other incorrect number error, and failure to include prior exam for comparison. In addition, report turnaround times were evaluated before and after the changes were made. Reporting time evaluations included 1-year volume prior to change (3915 reports) and 1month post-change (206 reports). Of 100 DEXA exams before the change, 15 final reports contained 25 numerical errors. After the change, no numerical errors in the reports were identified. Exam end to final report time decreased from 2159 to 625min on average. Automating data transmittal from the DXA modality for report generation improves accuracy and turnaround time. This approach did not require any third party software, and healthcare information security concerns were negated since we are using our standard workstations. Secondary to the affordability and applicability to the large percentage of the population using electronic medical record systems, this type of automated workflow is recommended.

Association of Bone Mineral Density to Dietary Intake and Predictors of Breast Cancer in Premenopausal and Postmenopausal Malaysian Women

Daily food intake of women may affect their bone health by altering their bone mineral density (BMD) as the lack of certain nutrients may affect bone integrity whilst, BMD also can be a predictor of breast cancer. To date, many studies have been conducted to discuss on association of BMD and mammographic breast density (MBD) and how both are related to breast cancer risks but no consideration has been made on dietary intake. Therefore, this study was designed to determine the association of dietary intake with BMD and other breast cancer risk factors. A cross-sectional study on 76 pre- and postmenopausal women above 40 years underwent mammogram screening and Dual Energy X-ray Absorptiometry (DEXA) was conducted in Hospital Kuala Lumpur (HKL) for the duration of 1 year. Purposive sampling method was used to choose the respondents. Women who are diagnosed with breast cancer and underwent cancer treatment were excluded from this study. DEXA unit (Hologic Discovery W, Hologic, Inc) were used to measure BMD at the femoral neck and lumbar spine in grams per centimetre squared (g/cm2 ) and they were classified into normal and abnormal group based on the T-scores. The subjects were asked about their daily dietary pattern for a duration of three days using Diet History Questionnaire (DHQ). The mean of selected characteristics were compared between groups. Additionally, binary logistic regression was used to determine the association between diet intake with BMD and other risk factors of breast cancer. The total number of pre- and postmenopausal women who consented to participate in this study are equal. The mean age was 47.1 years and 54.9 years for premenopausal and postmenopausal women respectively. The results indicate only menopausal age of the women was statistically significant (p < 0.05). A number of 17% premenopausal and 9% of postmenopausal women showed to have family history of breast cancer, however, it was not statistically significant (p = 0.12). There was no significant difference in daily energy intake of food in both groups (p = 0.22). None of the nutrients in daily food intake showed to be statistically significant. Menstrual status showed an association with BMD with p < 0.05 and the remaining risk factors did not show any association. Logistic regression revealed that only menstrual status had correlation with BMD in both groups. This study provided the dietary pattern and the effects on bone health. The association of other risk factors of breast cancer with BMD were also analysed and most of it showed a negative association. DOI : http://dx.doi.org./10.17576/JSKM-2017-1502-19

Factors Associated with Osteoporosis among Women Diagnosed by Using Dual Energy X-ray Absorptiometry (DEXA)

Background: Osteoporosis is a major public health problem, because it is lead to weakness of the skeleton and increased risk of fractures particularly of the spine and hip, increased morbidity and mortality, and which are a huge burden on the health system due to the high economic costs of those care fractures they produced. Objective: to identify some factors associated with occurrence of osteoporosis among women in AL-Najaf province Methodology: A descriptive study was conducted in DEXA unit in radiology department in Al-Sader Teaching Hospital in AL-Najaf Province /Iraq from August 2014 till the end of March 2015.A purposive sample was (150) woman who referred for investigation osteoporosis by using DEXA measurement. Data were gathered by direct interview with the women using especial questionnaire that include questions about socio-demographic characteristics such as age of women, level of education, residency, reproductive variables such as menopausal age, medical history such as hypertension, diabetic mellitus, body mass index (BMI) and physical activities. Results: The results indicated that the osteoporosis in this study was 45.3%. The most of osteoporosis (75%) within age group (&gt; 60) years, (53.7%) woman at menopause, (67.8%) were smoking, (31.3%) had renal problems. The present study showed that (85%) of women with osteoporosis had normal body mass index, while (31.1%) were obese (30+). In addition to, the study revealed that (60%)of women with osteoporosis were within low physical activities levels. Conclusion :The study concludes that the osteoporosis was significantly associated with body mass index, current age, renal problems, Recommendations: the researcher recommended that all women above 50 years to be done DEXA examination yearly or every two years to decrease possibility of osteoporosis .

Cross-calibration of pencil-beam (DPX-NT) and fan-beam (QDR-4500C) dual-energy X-ray absorptiometry for sarcopenia.

Sarcopenia, defined as the loss of muscle mass accompanied by weakness, is an important factor leading to frailty and is a growing concern in the aging Japanese society. Muscle mass can be calculated by dual-energy X-ray absorptiometry (DXA), but results differ between devices produced by different manufactures. Thus, cross-calibration is needed to compare body composition results in multicenter trials or when scanners are replaced. The purpose of this study was to perform an in vivo calibration of total body scans between pencil-beam (DPX-NT, GE Healthcare) and fan-beam (QDR-4500C, Hologic Inc.) DXA units. A total 30 subjects (15 women, 15 men, mean age = 35 years, range 22-49 years) were recruited. The lumbar bone mineral density (BMD), femoral neck BMD, appendicular fat and lean body mass, and the appendicular skeletal muscle mass index (ASMI) were highly correlated (r = 0.979-0.993, r(2) = 0.889-0.977). The conversion formulas were as follows: lumbar BMD, Y = -0.08 + 1.16X (X = QDR-4500C, Y = DPX-NT), femoral neck BMD, Y = -0.015 + 1.11X, and ASMI Y = 0.92 + 0.90X. There is excellent comparability between the DPX-NT and the QDR-4500C DXA units. However, cross-calibration equations are required to assess muscle volume, fat, and ASMI in multicenter studies investigating sarcopenia.

A DXA Whole Body Composition Cross-Calibration Experience: Evaluation With Humans, Spine, and Whole Body Phantoms

New densitometer installation requires cross-calibration for accurate longitudinal assessment. When replacing a unit with the same model, the International Society for Clinical Densitometry recommends cross-calibrating by scanning phantoms 10 times on each instrument and states that spine bone mineral density (BMD) should be within 1%, whereas total body lean, fat, and %fat mass should be within 2% of the prior instrument. However, there is limited validation that these recommendations provide adequate total body cross-calibration. Here, we report a total body cross-calibration experience with phantoms and humans.Cross-calibration between an existing and new Lunar iDXA was performed using 3 encapsulated spine phantoms (GE [GE Lunar, Madison, WI], BioClinica [BioClinica Inc, Princeton, NJ], and Hologic [Hologic Inc, Bedford, MA]), 1 total body composition phantom (BioClinica), and 30 human volunteers. Thirty scans of each phantom and a total body scan of human volunteers were obtained on each instrument.All spine phantom BMD means were similar (within 1%; <−0.010 g/cm2 bias) between the existing and new dual-energy X-ray absorptiometry unit. The BioClinica body composition phantom (BBCP) BMD and bone mineral content (BMC) values were within 2% with biases of 0.005 g/cm2 and −3.4 g. However, lean and fat mass and %fat differed by 4.6%–7.7% with biases of +463 g, −496 g, and −2.8%, respectively. In vivo comparison supported BBCP data; BMD and BMC were within ∼2%, but lean and fat mass and %fat differed from 1.6% to 4.9% with biases of +833 g, −860 g, and −1.1%. As all body composition comparisons exceeded the recommended 2%, the new densitometer was recalibrated. After recalibration, in vivo bias was lower (<0.05%) for lean and fat; −23 and −5 g, respectively. Similarly, BBCP lean and fat agreement improved.In conclusion, the BBCP behaves similarly, but not identical, to human in vivo measurements for densitometer cross-calibration. Spine phantoms, despite good BMD and BMC agreement, did not detect substantial lean and fat differences observed using BBCP and in vivo assessments. Consequently, spine phantoms are inadequate for dual-energy X-ray absorptiometry whole body composition cross-calibration.

Should Dual-Energy X-ray Absorptiometry Technologists Estimate Dietary Calcium Intake at the Time of DXA?

Adequate calcium intake is essential for bone health. Calcium is obtained from dietary sources and supplementation. Knowing the daily dietary calcium intake is helpful in deciding on the need for supplementation. Dietary calcium intake can be estimated quickly and accurately using an approach recommended by the National Osteoporosis Foundation. We sought to evaluate the usefulness of estimating dietary calcium intake by a technologist at the time of attendance for dual-energy X-ray absorptiometry (DXA) scanning. We conducted a retrospective survey of results on estimated dietary calcium intake in adults attending our DXA unit over 2 years (n = 5569). We assessed intake with reference to the specifications of the Institute of Medicine according to sex and age. The average intake was 736 mg daily: Young adults had higher intakes than older adults (p < 0.001), and men had higher intakes than women (p = 0.017). According to Institute of Medicine's specification, we estimate that nearly 45% of Irish women need supplemental intake of 500 mg daily but <4% need supplemental intake of 1000 mg daily. Younger adults are apt to have intakes within, or higher than, the requirement. Having DXA technologists estimate dietary calcium intake at the time of DXA scanning may provide helpful information to the referring clinicians about the need for supplementation.

The accuracy and precision of DXA for assessing body composition in team sport athletes

This study determined the precision of pencil and fan beam dual-energy X-ray absorptiometry (DXA) devices for assessing body composition in professional Australian Football players. Thirty-six professional Australian Football players, in two groups (fan DXA, N = 22; pencil DXA, N = 25), underwent two consecutive DXA scans. A whole body phantom with known values for fat mass, bone mineral content and fat-free soft tissue mass was also used to validate each DXA device. Additionally, the criterion phantom was scanned 20 times by each DXA to assess reliability. Test–retest reliability of DXA anthropometric measures were derived from repeated fan and pencil DXA scans. Fat-free soft tissue mass and bone mineral content from both DXA units showed strong correlations with, and trivial differences to, the criterion phantom values. Fat mass from both DXA showed moderate correlations with criterion measures (pencil: r = 0.64; fan: r = 0.67) and moderate differences with the criterion value. The limits of agreement were similar for both fan beam DXA and pencil beam DXA (fan: fat-free soft tissue mass = −1650 ± 179 g, fat mass = −357 ± 316 g, bone mineral content = 289 ± 122 g; pencil: fat-free soft tissue mass = −1701 ± 257 g, fat mass = −359 ± 326 g, bone mineral content = 177 ± 117 g). DXA also showed excellent precision for bone mineral content (coefficient of variation (%CV) fan = 0.6%; pencil = 1.5%) and fat-free soft tissue mass (%CV fan = 0.3%; pencil = 0.5%) and acceptable reliability for fat measures (%CV fan: fat mass = 2.5%, percent body fat = 2.5%; pencil: fat mass = 5.9%, percent body fat = 5.7%). Both DXA provide precise measures of fat-free soft tissue mass and bone mineral content in lean Australian Football players. DXA-derived fat-free soft tissue mass and bone mineral content are suitable for assessing body composition in lean team sport athletes.

Informatics in Radiology: Use of a Macro Scripting Editor to Facilitate Transfer of Dual-Energy X-ray Absorptiometry Reports into an Existing Departmental Voice Recognition Dictation System

The process of verbally reporting or manually retyping numeric data generated at dual-energy x-ray absorptiometry (DXA) involves numerous pitfalls. With use of a macro scripting editor, a customized macro was created to automate the transfer of data generated by a DXA scanner into a structured voice recognition dictation system without requiring radiologists to type in a medical record number or accession number to identify the study. A preliminary report is generated with use of software for a DXA unit and a customized template that includes numeric and qualitative assessments of osteoporosis as well as data from prior studies if available. A customized macro is then invoked by the macro scripting editor, which selectively transfers the report from the draft document into the voice recognition dictation system, thereby producing a final structured diagnostic report. All of the radiologists surveyed to evaluate this automated method reported ease of software use and greater efficiency in report production. In addition, a random audit of the 800 DXA scans that have been reported with this technique demonstrated no reports generated under an incorrect accession number and no incorrect transfer of data. Automated DXA reporting is now the preferred method of dictation at the authors' institution and represents an inexpensive, accurate, and customizable means of DXA reporting.

Strength of Anterior Vertebral Screw Fixation in Relationship to Bone Mineral Density

A biomechanical study was performed to investigate the relationship among the pullout strength of anterior vertebral screw fixation, bone mineral density (BMD) of the vertebral body, screw insertion torque, and width of the vertebral body. BMD was measured using a dual energy x-ray absorptiometry unit. Screw insertion torque and width of the lumbar vertebrae were also measured before the pullout test. Pullout strength was significantly correlated with BMD (r = 0.85) and screw insertion torque (r = 0.47), but not with width of the vertebral body. Multiple regression analyses demonstrated better correlation between pullout strength and the other parameters (r = 0.886). A stepwise regression analysis showed that BMD is the most significant predictor of the pullout strength followed by width of the vertebral body, whereas screw insertion torque is not a significant predictor. Furthermore, the mean pullout strength of the grade I osteoporosis group was significantly greater than that of grade II or III osteoporosis group.