Objective measurements of image quality in synchrotron radiation phase-contrast imaging versus digital mammography.

PURPOSE: Phase-contrast mammography with synchrotron radiation is an innovative X-ray imaging practice that improves the identification of breast lesions. Previous studies have proven the superiority of the mammography images taken in the phase-contrast modality using synchrotron radiation beams as compared with images taken in conventional mammography by subjective analyses. However, to our knowledge, no previous study has compared different acquisition systems in order to quantify this improvement by means of objective robust indicators. In this research, we intend to quantify the superiority of phase-contrast imaging by means of objective metrics of image quality. METHODS: Images from the American College of Radiology Mammographic Accreditation Phantom were obtained at hospitals, in two digital mammography equipment and at the Elettra synchrotron radiation facility (Trieste, Italy), using free space propagation phase-contrast modality. Regions of interest were selected to analyze image quality at the fibers (phase object) and masses (area object) simulated on the phantom by means of the signal-to-noise ratio, the figure of merit, the contrast and the edge visibility. RESULTS: The image contrast and edge visibility were significantly higher at the phase-contrast modality as compared with digital mammography equipment. The figure of merit using phase-contrast modality was higher for the fibers and comparable for the masses. CONCLUSION: The results showed an improvement of the contrast and edge visibility in phase-contrast images. These improvements may be important in the detection of small lesions and details.

A comparative study of computed digital absorptiometry and conventional dual-energy X-ray absorptiometry in postmenopausal women.

The aim of the study was to evaluate whether computed digital absorptiometry (CDA) of the hand might be a useful screening technique for identifying patients with postmenopausal osteoporosis and to compare the results of CDA with those of dual-energy X-ray absorptiometry (DXA) of the lumbar spine and femoral neck. We studied 230 postmenopausal women (mean age 58.4 + 7.9 years). For CDA, bone mineral density (BMD) was measured with an AccuDEXA Schick densitometer in the third middle phalanx of the nondominant hand. For DXA, BMD of the lumbar spine and upper femur was assessed using a DXA Hologic QDR-1000 densitometer. We did a comparative analysis (ANOVA) and linear correlation tests. Sensitivity and specificity of CDA and receiver operating characteristic (ROC) curves for the diagnosis of osteoporosis were calculated. The mean BMD with CDA was 0.445 +/- 0.084 (T-score: -1.27 +/- 1.29). The mean BMD (g/cm2) with DXA at the lumbar spine was 0.877 +/- 0.166 (T-score: -1.52 +/- 1.59) and 0.708 +/- 0.127 at the femoral neck (T-score: -1.12 +/- 1.25). BMD at the lumbar spine and femoral neck correlated positively with CDA of the hand (r = 0.66 and r = 0.65 respectively, p<0.001). When using as cut-off a T-score of -2.5, according to WHO criteria, 76 women (33%) had osteoporosis of the lumbar spine and/or femoral neck with DXA and 42 (18%) with CDA (p<0.001). The kappa score for osteoporosis was 0.33 for CDA versus spinal DXA and 0.35 for CDA versus femoral DXA. With the cut-off level used, sensitivity and specificity of CDA in detecting osteoporosis at the lumbar spine were 0.39 and 0.90, respectively; sensitivity and specificity of CDA in identifying osteoporosis at the femoral neck were 0.58 and 0.87, respectively. The positive predictive value of CDA for osteoporosis was 69% and the negative predictive value was 75%. The area under the ROC curve for osteoporosis was 0.822 +/- 0.028. We conclude that: (a) CDA assessment has a moderate correlation with BMD measured by DXA at the lumbar spine and femoral neck; (b) CDA has a low sensitivity for the diagnosis of osteoporosis compared with spinal and femoral DXA; and (c) predictive values for osteoporosis at both the lumbar spine and femoral neck are acceptable.

Perfil clínico de las pacientes remitidas por ginecólogos a una unidad de densitometría del sector público / Clinical profile of patients referred by gynecologists to a densitometry unit of the public sector

Objetivos. Analizar el perfil clínico de las pacientes remitidas a una Unidad de Densitometría por ginecólogos. Métodos. Se envió por correo un cuestionario sobre factores de riesgo de fractura a 1.059 mujeres a las que se había evaluado mediante absorciometría dual de rayos X (DXA), la densidad mineral ósea (DMO). Resultados. Seiscientas noventa y cuatro mujeres (69,6%) contestaron (edad media: 54,2 ± 5,4 años); 120 (17,3%) presentaban osteoporosis. Más del 50% presentaba uno o ninguno de los factores de riesgo de fractura, tanto independientes (índice de masa corporal bajo, hábito tabáquico actual, antecedentes de fractura y antecedentes de fractura materna) como dependientes (menopausia precoz, ingesta cálcica baja e inmovilización prolongada) de la DMO incluidos en el cuestionario. Conclusiones. La prevalencia de osteoporosis y de factores de riesgo de fractura en las mujeres incluidas en el estudio es baja. La sensibilización frente al problema de la osteoporosis parece ser alta, según se desprende de la tasa de respuesta obtenida en el cuestionario

Objectives. To analize the clinical profile of the patients submitted to a Bone Densitometry Unit by gynaecologists. Methods. A questionnaire about risk factors of fracture was mailed to 1,059 women whose bone mineral density (BMD) had previously been evaluated by DXA. Results. 694 women (69.6%) answered (mean age: 54.2 ± 5.4 years); 120 (17.3%) presented osteoporosis. More than 50% presented none or one risk factors of fracture, either independent (low body mass index, current smoking habit, patient fracture history, maternal fracture history) or dependent (early menopause, low calcium intake, prolonged immobilisation) from BMD included in the questionnaire. Conclusions. The prevalence of osteoporosis and risk factors of fracture in the women included in the study is low. The sensitisation towards the problem of osteoporosis seems high, as suggested by the frequency of answers to the questionnaire obtained