Relationship between the visual evaluation of pathology visibility and the physical measure of low contrast detail detectability in neonatal chest radiography

IntroductionThe detectability of low contrast detail (LCD) is a method used to assess image quality (IQ) in neonatal radiography; however, there is a lack of data on the relationship between LCD detectability and visual IQ. The study aims at investigating the relationship between the LCD detectability and visual IQ and pathology visibility (PV).MethodsSeveral acquisition parameters were employed to obtain a group of images from a neonatal Gammex chest phantom. Three observers applied relative visual grading analysis (VGA) for assessing the IQ and PV. A simulated pneumothorax visibility (PNV) and simulated hyaline membrane disease visibility (HMV) represented PV. Next, a CDRAD 2.0 phantom was radiographed utilising the same acquisition protocols, and several paired images were obtained. With the use of CDRAD analyser software, the detectability of LCD was assessed and expressed by an image quality figure inverse (IQFi_inv) metric. The correlation between the IQF_inv and each of IQ, PNV and HMV was examined.ResultsThe physical measure (IQF_inv) and the visual assessment of IQ were shown to be strongly correlated (r = 0.95; p < 0.001). Using Pearson's correlation, the IQF_inv, PNV, and HMV were found to be strongly correlated (r = 0.94; p < 0.001) and (r = 0.92; p < 0.001), correspondingly.ConclusionResults of the study show that physical measures of LCD detectability utilising the CDRAD 2.0 phantom is strongly corelated with visual IQ and PV (PNV and HMV) and can be used to evaluate IQ when undertaking neonatal chest radiography (CXR).Implications for practiceThis study establishes the feasibility of utilising the physical measure (IQF_inv) and the CDRAD 2.0 phantom in routine quality assurance and neonatal CXR optimisation studies.     

Scatter dose calculation for anti-scatter linear grids in mammography

Monte Carlo simulations were used to optimize the geometry of a mammography anti-scatter linear grid to achieve minimum scatter-to-primary ratio (SPR) for different X-ray tube voltages. A single optimum design of the grid with 0.9 mm septa height, 12 μm septa thickness and 100 μm interspace thickness was found for breast phantom thicknesses between 30 and 80 mm. The optimal grid has 0.153–0.330 scatter-to-primary ratio, a Bucky factor (BF) less than 2.5 and a contrast improvement factor (CIF) of 1.3.     

Signal intensity of normal breast tissue at MR mammography on midfield: applying a random coefficient model evaluating the effect of doubling the contrast dose

Purpose

To prospectively investigate the effect on signal intensity (SI) of healthy breast parenchyma on magnetic resonance mammography (MRM) when doubling the contrast dose from 0.1 to 0.2 mmol/kg bodyweight.

Materials and methods

Informed consent and institutional review board approval were obtained. Twenty-five healthy female volunteers (median age: 24 years (range: 21–37 years) and median bodyweight: 65 kg (51–80 kg)) completed two dynamic MRM examinations on a 0.6 T open scanner. The inter-examination time was 24 h (23.5–25 h). The following sequences were applied: axial T2W TSE and an axial dynamic T1W FFED, with a total of seven frames. At day 1, an i.v. gadolinium (Gd) bolus injection of 0.1 mmol/kg bodyweight (Omniscan) (low) was administered. On day 2, the contrast dose was increased to 0.2 mmol/kg (high). Injection rate was 2 mL/s (day 1) and 4 mL/s (day 2). Any use of estrogen containing oral contraceptives (ECOC) was recorded. Post-processing with automated subtraction, manually traced ROI (region of interest) and recording of the SI was performed. A random coefficient model was applied.

Results

We found an SI increase of 24.2% and 40% following the low and high dose, respectively (P < 0.0001); corresponding to a 65% (95% CI: 37–99%) SI increase, indicating a moderate saturation. Although not statistically significant (P = 0.06), the results indicated a tendency, towards lower maximal SI in the breast parenchyma of ECOC users compared to non-ECOC users.

Conclusion

We conclude that the contrast dose can be increased from 0.1 to 0.2 mmol/kg bodyweight, if a better contrast/noise relation is desired but increasing the contrast dose above 0.2 mmol/kg bodyweight is not likely to improve the enhancement substantially due to the moderate saturation observed. Further research is needed to determine the impact of ECOC on the relative enhancement ratio, and further studies are needed to determine if a possible use of ECOC should be considered a compromising factor, if an MRM is indicated in a young woman.     

A phantom for the measurement of contrast detail performance in film-screen mammography.

A National Breast Cancer Screening Programme, based on X-ray mammography, has been introduced in the UK. The success of this screening programme is dependent on the production of high quality radiographs. There are various methods of assessing imaging performance in mammography, but contrast detail detectability measurements have an advantage in that the observation of radiographs is taken into consideration. The design and construction of a contrast detail phantom for the assessment of image quality in mammography is described. This phantom can be used to assess the imaging performance of mammographic film-screen combinations. The results of some measurements to verify the accuracy of the contrast predictions are presented together with some initial results of an investigation into the contrast detail performance of film-screen combinations used in mammography.     

The clinical utility of rib detail films in the evaluation of trauma

The objective of this study was to assess the clinical utility of rib detail films (RDFs) when used in addition to chest radiographs in the evaluation of thoracic trauma. A retrospective review of medical records of all patients who obtained RDFs over a 4-year period was carried out. The study participants included 480 adult trauma patients who received RDFs and chest radiographs. Patients were assessed for the presence or absence of rib fracture(s) on radiographs, clinical management, follow-up, and complications resulting from rib fractures. Fractures were identified in 97 (20%) patients by RDFs. There were 26 (27%) complications due to rib injury, all of which were visualized on chest radiographs but not RDFs. Follow-up demonstrated no delayed complications. Treatment was directed only at complications. Visualization of rib fracture alone does not result in any significant change in treatment or outcome for the patient. Therefore, RDFs for blunt chest trauma have a limited clinical utility.     

Clinical evaluation of a new digitizing device for improved film mammography

RATIONALE AND OBJECTIVES: The study was designed to evaluate a new digitizing device, the iView (Maxxvision, LLC, Gainesville, FL), which aims to replace the magnifying glass in mammography with real-time film digitization, display, and processing. MATERIALS AND METHODS: A receiver operating characteristic (ROC) experiment was performed with 5 certified mammographers and 114 mammograms that were read with and without the iView. A satisfaction survey was also conducted on the system's features and usefulness. RESULTS: Data analysis suggested that (1) Cancer sensitivity could improve with the use of the iView system. ROC area differences showed improvements from 2% to 24% although these were not always statistically significant. At a false positive rate of 0.2, the true positive rate increased up to 60% depending on the set of cases and the observer's experience. (2) Specificity could also be improved. At a true positive rate of 0.9, the false positive rate decreased by as much as 55%. (3) Most observers felt more confident in their decisions when using the iView, although the prototype's ergonomic problems did not allow full utilization of its capabilities. CONCLUSION: Our pilot clinical study showed that the iView has the potential to improve mammogram interpretation. In addition, the system could broaden the applicability of electronic information and provide wider access to digital technology through a relatively simple and cost-effective approach. Observers recommended several improvements in the ergonomics and default display of the system that are currently implemented by the company. A larger clinical study of the improved system is necessary to clearly demonstrate its clinical value for mammography.     

Optimization of tube potential-filter combinations for film-screen mammography: a contrast detail phantom study

This study evaluated how tube potential-filter combinations [with a molybdenum (Mo) anode and either an Mo or a rhodium (Rh) filter] influence image quality and radiation dose to breasts of different thicknesses in film-screen mammography using a new mammography phantom (CDMAM Phantom Type 3.4). A 28-kVp/Mo tube potential-filter combination is recommended for a breast (phantom) thickness of 40 mm or less, 28 kVp/Rh for a breast (phantom) thickness of 60 mm or less, and 30 kVp/Rh for a breast (phantom) thickness greater than 60 mm.     

Dose and image-quality evaluation in synchrotron radiation mammography

Monochromatic X-ray beam produced by synchrotron radiation may be considered an ideal probe in some fields of diagnostic radiology. In this paper the potential of monochromatic synchrotron radiation X-ray beam in mammography is analyzed. The image quality of four different phantom radiographs, obtained using two different energies equal to 17 and 18 keV, respectively, and a mammographic film/screen system, is assessed. The doses have been determined for both energies by using thermoluminescent dosimeters and a 5-cm thick phantom having a composition of 50% water and 50% fat. The results have been compared with those obtained in the same manner using a mammographic unit equipped with a molybdenum anode, molybdenum filter tube and antiscanner grid. The radiographs obtained with synchrotron radiation show higher contrast and less blur than those obtained with a conventional mammographic system. The average breast doses, 1.55 and 0.80 mGy at 17 and 18 keV, respectively, are comparable with the dose (1.51 mGy) of the conventional technique. Correspondence to: M. Gambaccini     

全数字化乳腺摄影对妇女致密型乳腺病变的诊断价值

目的探讨全数字化乳腺摄影（FFDM）对妇女致密型乳腺病变的诊断价值。方法搜集2003年4月至2004年9月门诊及体检者行FFDM的3500余例中致密型乳腺的66例乳腺癌及6例癌前病变，12例囊性增生症，58例纤维腺瘤，1例结核，4例囊肿，11例乳腺腺病作为研究对象。全部病例采用美国GE公司的平板2000D全数字化乳腺摄影机检查，并经病理证实。检查体位常规采用头足位（CC）、内外斜位（MLO），必要时加摄侧位及局部点片。对临床未触及肿块的乳腺癌，均行术前定位。结果72例乳腺癌及癌前病变中，临床触及肿块者57例，未触及肿块者15例。影像表现为肿块23例；肿块并微小钙化18例；片状弥漫微小钙化伴局部结构紊乱11例；结构紊乱并粗长毛刺12例；簇状微小钙化2例；片簇状微小钙化1例；结构紊乱1例；小星状结构1例；长毛刺星状结构1例；平片无明显影像表现2例，其中1例仅导管造影显示僵硬、中断。共发现假阳性10例，假阴性5例，得出FFDM对乳腺癌诊断的敏感性、特异性、准确性分别为93．06％、88．37％、90．51％。良性病变中，58例纤维腺瘤，表现为肿块38例，肿块伴钙化20例；12例囊性增生症，表现为肿块10例，肿块伴点状钙化2例；11例乳腺腺病，表现为肿块9例，肿块伴点状钙化2例。4例囊肿和1例结核，均表现为肿块。结论FFDM能清晰显示乳腺癌的直接及间接征象，尤其能够显示致密乳腺的结构紊乱、粗长毛刺及微小钙化，对临床未触及肿块的乳腺癌及癌前病变具有重要的诊断价值。