A statistical alternative to current measures of image quality in digital mammography

Objective. Mammogram image quality in European breast screening systems is defined by threshold gold thickness (T) assessment of the CDMAM contrast-detail phantom. Previous studies have outlined several limitations of the phantom including expense, number of images required and inter-phantom manufacturing variability. Two alternative approaches to image quality assessment for routine quality control are examined and compared to the CDMAM technique: (i) A detectability index (d′) based on a non-prewhitened model observer with an eye filter (NPWE) and (ii) A statistical estimate of contrast based on image noise levels (CSTAT ). Approach. The d′ calculation follows a previously published methodology based on the NNPS and contrast, both measured from an image of 5 cm of PMMA containing a 0.2 mm Al target, as well as the MTF measured under standard conditions. For the proposed statistical method, pixels in the centre of the same NNPS image were re-binned into a range of equivalent CDMAM target areas. For any area, the minimum contrast necessary to distinguish a signal from the background, CSTAT , is 3.29σ at a 95% level of confidence, where σ is the standard deviation of the background pixels. Theoretical analysis predicts a simple relationships between CSTAT , T and d′. Measured values of CSTAT were compared to T and d′ as a function of air kerma at the detector for ten digital mammography systems from three different manufacturers. Main Results. Theoretical relationships between CSTAT , d′ and T were demonstrated. Minimum acceptable image quality performance for 0.10 and 0.25 mm diameter discs, defined by the European Guidelines in terms of T, are equivalent to d′ values of 0.85 and 5.36 and threshold CSTAT values of 0.055 and 0.022. Significance. Strong correlations between log(T), log(d′) and log(CSTAT ) suggest that either alternative approach produces information corresponding to that obtained using the CDMAM. CSTAT should be considered as a simple, objective and cost-effective alternative to routine image quality assessment in mammography.

Evaluation of microcalcification contrast in clinical images for digital mammography and synthetic mammography

PURPOSE

The aim of this work was to compare, in a clinical study, digital mammography and synthetic mammography imaging by evaluating the contrast in microcalcifications of different sizes.

METHODS

A retrospective review of microcalcifications from 46 patients was undertaken. A Hologic 3-Dimensions mammography system and a HD Combo protocol was used for simultaneous acquisition of the digital and synthetic images. Microcalcifications were classified in accordance with their size, and patient breast images were classified in accordance with their density as adipose, moderately dense and dense. The contrast of the microcalcifications was measured and the contrast ratio between synthetic and digital images was compared. An additional qualitative assessment of the images was presented to correlate the conspicuity of the microcalcifications with the suppression of the structure noise.

RESULTS

Microcalcifications in adipose background always exhibit a comparable or better contrast on synthetic images, regardless their size. For moderately dense background, synthetic images show a better contrast in 91.2 % of cases for small microcalcifications and in 90.9 % of cases for large microcalcifications. For a dense background, better contrast is seen in 89.5 % of cases for small microcalcifications, and in 85.7 % of cases for large microcalcifications. The contrast ratio increases with increasing breast glandularity. The suppression of structure noise also contributes to the enhancement of microcalcifications in the synthetic images.

CONCLUSIONS

Synthetic mammography imaging is superior to digital mammography imaging in terms of microcalcification contrast, regardless their size and breast density.

Measurement of selected androgens using liquid chromatography-tandem mass spectrometry in reproductive-age women with Type 1 diabetes

STUDY QUESTION

What information does androgen profiling using liquid chromatography tandem mass spectrometry (LC-MS/MS) provide in reproductive-age women with Type 1 diabetes (T1D)?

SUMMARY ANSWER

In T1D women, androstenedione proved most useful of the measured androgens in differentiating subgroups based on clinical phenotypes of hyperandrogenism (HA) and polycystic ovary syndrome (PCOS).

WHAT IS KNOWN ALREADY

The prevalence of HA and PCOS are increased in women with T1D. These observations are based on measurement of serum androgens using immunoassays, to-date no studies using LC-MS/MS have been reported in reproductive-age women with T1D.

STUDY DESIGN, SIZE, DURATION

This was a cross-sectional study with recruitment of three groups of reproductive-age women: women with T1D (n = 87), non-diabetic women with (N = 97) and without PCOS (N = 101).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Using LC-MS/MS, we aimed to characterize androgen profiles and PCOS status in women with T1D, and interpret findings in relation to cohorts of non-diabetic women with and without PCOS.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared to non-diabetic women, dehydroepiandrosterone/dehydroepiandrosterone sulphate (DHEA/DHEAS) ratio was lower (P < 0.05) in women with T1D. Testosterone levels were greater in T1D women with clinical HA and anovulation compared to those without clinical HA and with regular cycles, while androstenedione levels were greater in T1D women with HA and anovulation compared to those with HA and regular cycles and also those without HA and with regular cycles (P < 0.05 for all). Compared to T1D women without PCOS, the 18% of T1D women who had PCOS were younger with lower BMI, an older age of menarche, and were more likely to have a positive family history of PCOS (P < 0.05 for all). Androgen levels did not differ between women with T1D and PCOS compared to BMI-matched non-diabetic women with PCOS, but androstenedione levels were greater in T1D women with PCOS compared to obese women with PCOS (P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

Relatively small subgroups of patients were studied, reducing the power to detect small differences. Free testosterone levels were not measured using equilibrium dialysis, and were not calculated - commonly used formulae have not been validated in T1D.

WIDER IMPLICATIONS OF THE FINDINGS

Androstenedione is a sensitive biochemical marker of clinical hyperandrogenism and PCOS in T1D. T1D women with PCOS are leaner than those without PCOS but are more likely to have a family history of PCOS. Women with T1D and PCOS have a similar biochemical phenotype to lean non-diabetic women with PCOS but differ from obese women with PCOS. The mechanisms underlying PCOS in T1D and its clinical significance require further investigation.

STUDY FUNDING/COMPETING INTEREST(S)

The study was part-funded by the Meath Foundation. The authors have no competing interests.

A practical description and student perspective of the integration of radiology into lower limb musculoskeletal anatomy

BACKGROUND

Anatomy educators are increasing their utilisation of radiology in anatomy education in line with growing requirements for undergraduate radiology competency and clinical need.

AIMS

We aimed to evaluate student perceptions of radiology and to outline the technical and academic considerations underlying the integration of radiology into musculoskeletal practical anatomy sessions.

MATERIALS AND METHODS

The formal integration of radiology into anatomy practical sessions took place over a 5-week period during the lower limb musculoskeletal component of the anatomy course taught to first-year medical students. During practical sessions, students were required to rotate between aligned audio-visual radiology presentations, osteology/anatomical models, and prosection/dissection learning stations. After completing the course, students were invited to complete a survey to establish their opinions on radiology as a mode of learning and their satisfaction with radiological integration in anatomical practical sessions.

RESULTS

Most students were not familiar with radiology prior to attending our university. All our students agreed or strongly agreed that learning to read radiographs in anatomy is important and most agreed that radiology is a valid assessment tool. Sixty percent stated that radiology facilitated their understanding of anatomy. The majority believed that radiology was best suited to clinically relevant anatomy and X-rays were their preferred learning tool.

CONCLUSIONS

The practical approach to integrating radiology into undergraduate musculoskeletal anatomy described here did not place strain on existing academic resources. Most students agreed that radiology should be increased in anatomy education and that learning to understand radiographs in anatomy was important for clinical practice.

Experience with the European quality assurance guidelines for digital mammography systems in a national screening programme

The transition to a fully digital breast screening programme, utilising three different full-field digital mammography (FFDM) systems has presented many challenges to the implementation of the European guidelines for physico-technical quality assurance (QA) testing. An analysis of the QA results collected from the FFDM systems in the screening programme over a 2-y period indicates that the three different systems have similar QA performances. Generally, the same tests were failed by all systems and failure rates were low. The findings provide some assurance that the QA guidelines are being correctly implemented. They also suggest that there is more scope for the development of the relevance of the guidelines with respect to modern FFDM systems. This study has also shown that a summary review of the QA data can be achieved by simple organisation of the QA data storage and by automation of data query and retrieval using commonly available software.

Scatter radiation intensities around full-field digital mammography units

The aim of this study was to investigate the scatter radiation intensity around digital mammography systems and apply these data to standard shielding calculations to reveal whether shielding design of existing breast screening rooms is adequate for the use of digital mammography systems. Three digital mammography systems from GE Healthcare, Hologic and Philips were employed in the study. A breast-equivalent phantom was imaged under clinical workload conditions and scatter radiation intensities around the digital mammography systems were measured for a range of angles in three planes using an ionisation chamber. The results were compared with those from previous studies of film-screen systems. It may be deduced from the results that scattering in the backward direction is significant for all three systems, while scattering in the forward direction can be significant for some planes around the GE and Hologic systems. Measurements at typical clinical settings on each system revealed the Philips system to have markedly lower scatter radiation intensities than the other systems. Substituting the measured scattered radiation intensity into shielding calculations yielded barrier requirements similar to those already in place at the screening centres operating these systems. Current radiation protection requirements based on film-screen technology remain sufficient when applied to rooms with digital mammography installations and no alteration is required to the structural shielding.

Leucocytosis in women with polycystic ovary syndrome (PCOS) is incompletely explained by obesity and insulin resistance

OBJECTIVES

Low-grade chronic inflammation predicts cardiovascular outcomes and is observed in women with polycystic ovary syndrome (PCOS). Whether this is entirely a cause or consequence of insulin resistance (IR) is unknown.

METHODS

Seventy pairs of women with and without PCOS, matched for age, body mass index (BMI) and IR (HOMA, QUICKI and Avignon index), were generated from a larger cohort of 103 women with and 104 BMI-matched women without PCOS. Women with PCOS were studied in the follicular phase of the menstrual cycle. White cell count (WCC), high-sensitivity CRP (hsCRP) and a series of 12 cytokines and growth factors were measured. These inflammatory markers were also compared between women with PCOS and 10 normal women studied in the follicular, peri-ovulatory and luteal stages.

RESULTS

When all subjects were compared, WCC (6.75 × 10(9) vs 5.60 × 10(9 ) g/l, P < 0.005), hsCRP (4.04 vs 2.90 mg/l, P < 0.05) and IL-6 (1.11 vs 0.72 pg/ml, P < 0.05) were greater in women with PCOS. Pair-matching for IR eliminated between-group differences in hsCRP and cytokines but did not alter the difference in WCC (6.60 × 10(9) vs 5.60 × 10(9 ) g/l, P < 0.005). WCC was greater in PCOS compared to normal women at all stages of the menstrual cycle.

CONCLUSIONS

Low-grade inflammation occurs in PCOS. Increased hsCRP and cytokines are associated with IR, but increased WCC is observed even when IR is accounted for. The explanation for this and its clinical significance is unknown.

Comparison of the clinical performance of three digital mammography systems in a breast cancer screening programme

This study compares the clinical performance of three digital mammography system types in a breast cancer screening programme. 28 digital mammography systems from three different vendors were included in the study. The retrospective analysis included 238 182 screening examinations of females aged between 50 and 64 years over a 3-year period. All images were double read and assigned a result according to a 5-point rating scale to indicate the probability of cancer. Females with a positive result were recalled for further assessment imaging and biopsy if necessary. Clinical performance in terms of cancer detection rate was analysed and the results presented. No statistically significant difference was found between the three different mammography systems in a population-based screening programme, in terms of the overall cancer detection rate or in the detection of invasive cancer and ductal carcinoma in situ. This was shown in both prevalent and subsequent screening examination categories. The results demonstrate comparable cancer detection performance for the three imaging system types operational in the screening programme.

Clinical dose performance of full field digital mammography in a breast screening programme

OBJECTIVE

BreastCheck, the Irish Breast Screening Programme, has employed three different models of a full field digital mammography (FFDM) system since its transition to a digital service in 2007. The three models from GE Healthcare, Hologic and Sectra exhibit differences in their design and function, the most significant of which include anode target/filter choice, detector technology and the type of exposure automation.

METHODS

The aim of this study was to use the results from a clinical breast dose survey to examine the differences between three different FFDM models in terms of exposure selection, breast mean glandular dose (MGD) and automatic exposure control (AEC) dose contribution.

RESULTS

The accuracy of the dose estimation was improved by inclusion of the AEC pre-exposure dose contribution. The photon-counting system demonstrated the lowest average MGD. The GE Healthcare and Hologic flat-panel detector systems demonstrated a small but statistically significant dose difference. The pre-exposure dose contribution did not exceed 13% of the total exposure dose for any system in the survey. A comparison of the system calculated organ dose estimate from each machine with the corresponding MGD calculated from medical physics measurements indicated reasonably accurate organ dose estimates for most systems in the survey.

CONCLUSION

The results of this study provide a comprehensive assessment of the breast dose performance of current digital mammography systems in a clinical screening setting.

Comprehensive dose survey of breast screening in Ireland

The primary purpose of this study was to evaluate the impact of digital mammography screening on breast dose by analysing the results of a patient dose survey of the Irish breast screening programme. Results from the survey were used to determine a dose reference level for the screening programme. Approximately, 100 examinations were acquired for each of the digital mammography systems operational in the screening programme. Each examination consisted of two standard views of each breast. The mean glandular dose for each acquired image was calculated. The dose reference level was established by calculating the 95th percentile of the average mean glandular dose for the average compressed breast thickness of the mediolateral oblique views. The overall average mean glandular dose per examination was 2.72 ± 0.04 mGy. The average compressed breast thickness was 61.4 ± 0.03 mm. The average compression force was 109 ± 7 N. A dose reference level value of 1.75 mGy was established for the screening programme. The results of this clinical dose survey provide a valuable indication of the dose performance of modern full field digital mammographic imaging systems. The results demonstrate clearly the dose benefits of digital mammography. The dose benefit of digital screening was further demonstrated by the establishment of a comparatively lower diagnostic reference level for the screening programme. The comparison of the dose performance of individual X-ray systems with the diagnostic reference level highlights the need for more optimisation within the service.

Lipoprotein subclass patterns in women with polycystic ovary syndrome (PCOS) compared with equally insulin-resistant women without PCOS

OBJECTIVES

Women with polycystic ovary syndrome (PCOS) are more insulin resistant and display an atherogenic lipid profile compared with normal women of similar body mass index (BMI). Insulin resistance (IR) at least partially underlies the dyslipidemia of PCOS, but it is unclear whether PCOS status per se confers additional risk.

RESEARCH DESIGN AND METHODS

Using a case-control design, we compared plasma lipids and lipoprotein subclasses (using polyacrylamide gel tube electrophoresis) in 70 women with PCOS (National Institutes of Health criteria) and 70 normal women pair matched for age, BMI, and IR (homeostasis model assessment-IR, quantitative insulin sensitivity check index, and the Avignon Index). Subjects were identified as having a (less atherogenic) type A pattern consisting predominantly of large low-density lipoprotein (LDL) subfractions or a (more atherogenic) non-A pattern consisting predominantly of small-dense LDL subfractions.

RESULTS

Total, high-density lipoprotein, or LDL cholesterol, or triacylglycerol did not differ between the groups, but very low-density lipoprotein levels (P<0.05) were greater in women with PCOS, whereas a non-A LDL profile was seen in 12.9% compared with 2.9% of controls (P<0.05, chi2). Multiple regression analysis revealed homeostasis model assessment-IR and waist circumference to be independent predictors of very low-density lipoprotein together explaining 40.2% of the overall variance. Logistic regression revealed PCOS status to be the only independent determinant of a non-A LDL pattern (odds ratio 5.48 (95% confidence interval 1.082-27.77; P<0.05).

CONCLUSIONS

Compared with women matched for BMI and IR, women with PCOS have potentially important differences in lipid profile with greater very low-density lipoprotein levels and increased rates of a more atherogenic non-A LDL pattern.

High-molecular-weight adiponectin is selectively reduced in women with polycystic ovary syndrome independent of body mass index and severity of insulin resistance

CONTEXT

High-molecular-weight (HMW) adiponectin contributes to insulin resistance (IR), which is closely associated with the pathophysiology of polycystic ovary syndrome (PCOS). Abnormalities in adipocyte function have been identified in PCOS and potentially contribute to lower adiponectin concentrations.

OBJECTIVE

Our objective was to determine which variables in plasma and adipose tissue influence HMW adiponectin in a well characterized cohort of women with PCOS.

DESIGN

This was a cross-sectional study.

SETTINGS AND PARTICIPANTS

A teaching hospital. Women with PCOS (n = 98) and body mass index (BMI)-matched controls (n = 103) (including 68 age-, BMI-, and IR-matched pairs).

INTERVENTIONS

A standard 75-g oral glucose tolerance test was performed for each participant. Subcutaneous adipose tissue samples were taken by needle biopsy for a subset of PCOS women (n = 9) and controls (n = 8).

MAIN OUTCOME MEASURES

Serum levels of HMW adiponectin and their relation to indices of insulin sensitivity, body composition, and circulating androgens as well as adipose tissue expression levels of ADIPOQ, TNFalpha, PPARgamma, and AR were assessed.

RESULTS

HMW adiponectin was significantly lower in women with PCOS compared with both BMI- and BMI- and IR-matched controls (P = 0.009 and P = 0.027, respectively). Although BMI and IR were the main predictors of HMW adiponectin, an interaction between waist to hip ratio and plasma testosterone contributed to its variance (P = 0.026). Adipose tissue gene expression analysis demonstrated that AR and TNFalpha (P = 0.008 and P = 0.035, respectively) but not ADIPOQ mRNA levels were increased in PCOS compared with controls.

CONCLUSIONS

HMW adiponectin is selectively reduced in women with PCOS, independent of BMI and IR. Gene expression analysis suggests that posttranscriptional/translational modification contributes to reduced HMW adiponectin in PCOS.

Investigation of the effect of anode/filter materials on the dose and image quality of a digital mammography system based on an amorphous selenium flat panel detector

A comparison, in terms of image quality and glandular breast dose, was carried out between two similar digital mammography systems using amorphous selenium flat panel detectors. The two digital mammography systems currently available from Lorad-Hologic were compared. The original system utilises Mo/Mo and Mo/Rh as target/filter combinations, while the new system uses W/Rh and W/Ag. Images of multiple mammography phantoms with simulated compressed breast thicknesses of 4 cm, 5 cm and 6 cm and various glandular tissue equivalency were acquired under different spectral conditions. The contrast of five details, corresponding to five glandular compositions, was calculated and the ratio of the square of the contrast-to-noise ratio to the average glandular dose was used as a figure-of-merit (FOM) to compare results. For each phantom thickness and target/filter combination, there is an optimum voltage that maximises the FOM. Results show that the W/Rh combination is the best choice for all the detection tasks studied, but for thicknesses greater than 6 cm the W/Ag combination would probably be the best choice. In addition, the new system with W filter presents a better optimisation of the automatic exposure control in comparison with the original system with Mo filter.

Dermatologic diseases of the breast and nipple

Breast and nipple skin is commonly affected by various inflammatory and neoplastic processes. Despite this fact, many physicians are unaware of the spectrum of diseases that can involve this area. Because breast and nipple skin represents a cosmetically, sexually, and functionally important entity to most patients, awareness of these disease entities is invaluable. This article reviews the normal anatomy of the breast, cutaneous manifestations of neoplastic processes that can present in these areas, and common inflammatory diseases of the breast and nipple skin.

Tc-99m tetrofosmin scintigraphy as an adjunct to plain-film mammography in palpable breast lesions

AIM

To investigate the use of Tc-99m tetrofosmin as a breast imaging agent and to compare results of Tc-99m tetrofosmin scintimammography with plain-film mammography and pathological outcome.

PATIENTS AND METHODS

Forty-four patients (mean age, 51 years; range 26-79 years) with a palpable breast mass requiring fine needle aspiration biopsy (FNAB) were prospectively studied. All patients had Tc-99m tetrofosmin scintimammography. Patients over 35 years of age had two view mammography performed on the same day. FNAB was performed within 2 weeks of imaging, and patients referred for surgery as appropriate. Results of scintigraphy and plain-film mammography were correlated with pathological outcome.

RESULTS

Of the 44 patients, 21 had biopsy proven malignancy while 23 had benign lesions. Of the 21 patients with carcinoma, 20 (95.2%) had positive Tc-99m tetrofosmin scintimammography while 21 (91.3%) of the 23 patients with benign histology had negative scintigraphy. The sensitivity of scintimammography was 95.24%, the specificity was 91.3%, with a positive predictive value of 90.9% and a negative predictive value of 95.45%. Thirty-eight patients had two view mammography performed (six patients were <35 years of age). Of these 38 patients, 21 had biopsy proven malignancy while 17 had benign histology (all patients <35 years of age had benign histology). Of the 21 patients with malignancy, plain-film mammography was suspicious for malignancy in 17 (81%) while four were reported as benign. Of the 17 with benign disease, 14 patients (82.4%) had benign appearances on plain-film mammography while three (18%) had one or more findings suspicious for malignancy. The sensitivity of plain-film mammography in our group was 81%, with a specificity of 82.4%, a positive predictive value of 85% and a negative predictive value of 77.8%. Tc-99m tetrofosmin scintimammography correctly characterized all seven lesions where mammographic evaluation was limited because of dense breast parenchyma or previous surgery and/or radiotherapy.

CONCLUSION

Tc-99m tetrofosmin scintimammography is an accurate, well tolerated and non-invasive method of differentiating benign from malignant palpable breast lesions. Negative Tc-99m tetrofosmin scintimammography excludes malignancy with a high degree of confidence while false-positive scintigraphy can occur in cases of proliferative dysplasia and hypercellular fibroadenoma. Tc-99m tetrofosmin scintimammography is particularly useful when plain-film mammography is indeterminate or limited in patients with dense breasts or a history of previous surgery and/or radiotherapy.

A comparison of SPECT and planar ventilation perfusion lung scanning

In order to define the role of Single Photon Emission Computed Tomography (SPECT) in the diagnosis of pulmonary embolus; SPECT and Planar ventilation and perfusion lung studies were performed consecutively on eleven patients referred with suspected embolus. Three patients were shown to have 'high probability' ventilation perfusion mismatches. SPECT imaging allowed segmental localisation of the perfusion defect and revealed additional defects not seen on planar scans. SPECT lung study was performed with minimal technical difficulty and was well tolerated by all patients studied. SPECT is likely to become the method of choice for investigating patients referred with suspected pulmonary embolus.