Image quality of opportunistic breast examinations in photon-counting computed tomography: A phantom study.

PURPOSE: To compare the breast imaging performance of a clinical whole-body photon-counting CT (PCCT) to that of a dedicated breast CT (BCT) to determine the image quality of opportunistic breast examinations in clinical PCCT. MATERIALS AND METHODS: To quantify image quality for breast cancer applications, acquisitions of a breast phantom including representations of calcifications, fibers, and masses were performed using a clinical PCCT and a dedicated BCT. When imaging with the PCCT, the phantom was also combined with a thorax phantom to simulate realistic patient positioning, while only the breast phantom was imaged in the BCT. Images in BCT were acquired at 7.0 mGy (CTDI16cm) and using 2.6 mGy-25.0 mGy in the PCCT. Spatial resolution between the BCT and PCCT images was matched and data were reconstructed using the default methods of each system. The dose-normalized contrast-to-noise ratio (CNRD) of masses and the structural visibility of fibers and calcifications were evaluated as figures of merit for all reconstructions. RESULTS: CNRD between masses and background was 0.56 mGy-½, on average with BCT and varied between 0.39 mGy-½ to 1.46 mGy-½ with PCCT over all dose levels, phantom configurations, and reconstruction algorithms. Calcifications down to a size of 0.29 mm and fibers down to a size of 0.23 mm could be reliably identified in the images of both systems. CONCLUSIONS: Clinical PCCT provides an image quality superior to that obtained with BCT in terms of CNRD and allows for the identification of calcifications and fibers at comparable dose levels.

Technical note: Characterization, validation, and spectral optimization of a dedicated breast CT system for contrast-enhanced imaging.

BACKGROUND: The development of a new imaging modality, such as 4D dynamic contrast-enhanced dedicated breast CT (4D DCE-bCT), requires optimization of the acquisition technique, particularly within the 2D contrast-enhanced imaging modality. Given the extensive parameter space, cascade-systems analysis is commonly used for such optimization. PURPOSE: To implement and validate a parallel-cascaded model for bCT, focusing on optimizing and characterizing system performance in the projection domain to enhance the quality of input data for image reconstruction. METHODS: A parallel-cascaded system model of a state-of-the-art bCT system was developed and model predictions of the presampled modulation transfer function (MTF) and the normalized noise power spectrum (NNPS) were compared with empirical data collected in the projection domain. Validation was performed using the default settings of 49 kV with 1.5 mm aluminum filter and at 65 kV and 0.257 mm copper filter. A 10 mm aluminum plate was added to replicate the breast attenuation. Air kerma at the isocenter was measured at different tube current levels. Discrepancies between the measured projection domain metrics and model-predicted values were quantified using percentage error and coefficient of variation (CoV) for MTF and NNPS, respectively. The optimal filtration was for a 5 mm iodine disk detection task at 49, 55, 60, and 65 kV. The detectability index was calculated for the default aluminum filtration and for copper thicknesses ranging from 0.05 to 0.4 mm. RESULTS: At 49 kV, MTF errors were +5.1% and -5.1% at 1 and 2 cycles/mm, respectively; NNPS CoV was 5.3% (min = 3.7%; max = 8.5%). At 65 kV, MTF errors were -0.8% and -3.2%; NNPS CoV was 13.1% (min = 11.4%; max = 16.9%). Air kerma output was linear, with 11.67 µGy/mA (R2 = 0.993) and 19.14 µGy/mA (R2 = 0.996) at 49 and 65 kV, respectively. For iodine detection, a 0.25 mm-thick copper filter at 65 kV was found optimal, outperforming the default technique by 90%. CONCLUSION: The model accurately predicts bCT system performance, specifically in the projection domain, under varied imaging conditions, potentially contributing to the enhancement of 2D contrast-enhanced imaging in 4D DCE-bCT.

Programa de control de calidad para optimizar dosis-calidad de imagen en un sistema de mamografía digital FFDM con DBT / Quality control program to optimize dose-image quality in a digital mammography system FFDM with DBT

El objetivo de este estudio fue establecer y mantener activo un programa de control de calidad semanal en un sistema de mamografía digital de campo completo (FFDM) con tomosíntesis digital de mama (DBT) para optimizar la relación dosis-calidad de imagen en el tamizaje mamográfico y en el diagnóstico de las patologías de la mama, así como determinar la sensibilidad y especificidad en el periodo 2019-2022. Las imágenes mamográficas fueron obtenidas con el maniquí del Colegio Americano de Radiología (ACR) como parte del programa de control de calidad y con el uso de un dosímetro se determinó la dosis glandular media (DGM). También se midieron otras variables que afectan calidad de imagen y dosis. La imagen optimizada tiene el potencial de reducir la tasa de mortalidad por cáncer de mama debido a que el cáncer de mama es un problema de salud pública en los países en vías de desarrollo. Los resultados generales en el periodo del estudio se ilustran con graficas e intervalos de confianza al 95% (IC, 95%), además los valores numéricos se expresan en términos del error estándar de la media con 95% de confianza. Para mamografía digital de campo completo (FFDM): mAs = 160 ± 3.74, kVp = 28, dosis glandular media (DGM) = 1.69 ± 0.02 mGy, razón señal-ruido (SNR) = 62.20 ± 0.67, razón contraste-ruido (CNR) = 12.16 ± 0.15 y para tomosíntesis digital de mama (DBT): mAs = 61.42 ± 1.14, kVp = 29, dosis glandular media (DGM) = 1.54 ± 0.01 mGy. Los valores de las diferentes variables fueron determinados de acuerdo a la metodología del fabricante (Hologic, 2011). Los valores de la sensibilidad y la especificidad fueron para mamografía digital de campo completo (FFDM) sensibilidad 91% y especificidad 94% y para tomosíntesis digital de mama (DBT) sensibilidad 94% y especificidad 97%. Los resultados de dosis y calidad de imagen en ambas modalidades mamografía digital de campo completo (FFDM) y tomosíntesis digital de mama (DBT) muestran que el programa de control de calidad se mantuvo operativo durante el estudio manteniendo una relación optimizada entre dosis y calidad de imagen

The objective of this study was to establish and maintain active a weekly quality control program in a full-field digital mammography (FFDM) system with digital breast tomosynthesis (DBT) to optimize the dose-image quality relationship in mammographic screening and in diagnosis of breast pathologies, as well as determining sensitivity and specificity in the period 2019-2022. Mammographic images were obtained with the American College of Radiology (ACR) phantom as part of the quality control program and the mean glandular dose (DGM) was determined with a dosimeter. Other variables that affect image quality and dose were also measured. Optimized imaging (image quality-dose) has the potential to reduce the breast cancer mortality rate because breast cancer is a public health problem in developing countries. The general results in the study period are illustrated with graphs and 95% confidence intervals (CI, 95%), in addition the numerical values are expressed in terms of the standard error of the mean with 95% confidence, For full field digital mammography (FFDM): mAs = 160.3 ± 3.74, kVp = 28, mean glandular dose (DGM) = 1.69 ± 0.02 mGy, signalto-noise ratio (SNR) = 62.20 ± 0.67, contrast-to-noise ratio (CNR) = 12.16 ± 0.15 and for tomosynthesis digital breast (DBT): mAs = 61.42 ± 1.14, kVp = 29, mean glandular dose (DGM) = 1.54 ± 0.01 mGy. The values of the different variables were determined according to the manufacturer's methodology. Mammography facility sensitivity and specificity values were determined using pathology results during the study. For FFDM mode they were sensitivity 91% and specificity 94% and for DBT mode they were sensitivity 94% and specificity 97%. The dose and image quality results in both full field digital mammography (FFDM) and digital breast tomosynthesis (DBT) modalities show that the quality control program remained operational during

Comparing image quality of five breast tomosynthesis systems based on radiologists' reviews of phantom data.

BACKGROUND: Previous studies have shown differences in technical image quality between digital breast tomosynthesis (DBT) systems. However, quantitative image quality measurements may not necessarily fully reflect the clinical performance of DBT. PURPOSE: To study the subjective image quality of five DBT systems manufactured by Fujifilm, GE, Hologic, Planmed, and Siemens using phantom images. MATERIAL AND METHODS: A TOR MAM test object with polymethyl methacrylate plates was imaged on five DBT systems from different vendors. Three DBT acquisitions were performed at mean glandular doses of 1.0 mGy, 2.0 mGy, and 3.5 mGy while maintaining a constant phantom set-up. Eight DBT acquisitions with different test plate positions and phantom set-up thicknesses were performed at clinically applied dose levels. Additionally, three conventional two-dimensional mammogram images were acquired with different phantom thicknesses. Six radiologists ranked the systems based on the visibilities of the targets seen in the phantom images. RESULTS: In the DBT acquisitions performed at comparable dose levels, one system differed significantly from all other systems in microcalcification scores. When using site-specific DBT protocols, significant differences were found between the devices for microcalcification, filament, and low-contrast targets. A strong correlation was observed between the reviewer scores and radiation doses in DBT acquisitions, whereas no such correlation was observed in the 2D acquisitions. CONCLUSION: In DBT acquisitions, dose level was found to be a major factor explaining image quality differences between the systems, regardless of other acquisition parameters. Most DBT systems performed equally well at similar dose levels.

National inventory of authorized diagnostic imaging equipment in Ghana: data as of September 2020.

Introduction: to address the challenge of inadequate and non-equitable distribution of diagnostic imaging equipment, countries are encouraged to evaluate the distribution of installed systems and undertake adequate monitoring to ensure equitability. Ghana´s medical imaging resources have been analyzed in this study and evaluated against the status in other countries. Methods: data on registered medical imaging equipment were retrieved from the database of the Nuclear Regulatory Authority and analyzed. The equipment/population ratio was mapped out graphically for the 16 regions of Ghana. Comparison of the equipment/population ratio was made with the situation in other countries. Results: six hundred and seventy-four diagnostic imaging equipment units from 266 medical imaging facilities (2.5 units/facility), comprising computed tomography (CT), general X-ray, dental X-ray, single-photon emission computed tomography (SPECT) gamma camera, fluoroscopy, mammography and magnetic resonance imaging (MRI) were surveyed nationally. None of the imaging systems measured above the Organization for Economic Co-operation and Development (OECD) average imaging units per million populations (u/mp). The overall equipment/population ratio estimated nationally was 21.4 u/mp. Majority of the imaging systems were general X-ray, installed in the Greater Accra and Ashanti regions. The regional estimates of equipment/population ratios were Greater Accra (49.6 u/mp), Ashanti (22.4 u/mp), Western (21.4 u/mp), Eastern (20.6 u/mp), Bono East (20.0 u/mp), Bono (19.2 u/mp), Volta (17.9 u/mp), Upper West (16.7 u/mp), Oti (12.5 u/mp), Central (11.9 u/mp), Northern (8.9 u/mp), Ahafo (8.9 u/mp), Upper East (6.9 u/mp), Western North (6.7 u/mp), Savannah (5.5 u/mp) and North-East (1.7 u/mp). Conclusion: medical imaging equipment shortfall exist across all imaging modalities in Ghana. A wide inter-regional disparity in the distribution of medical imaging equipment exists contrary to WHO´s recommendation for equitable distribution. A concerted national plan will be needed to address the disparity.

Using a mobile device for margin assessment of specimen mammography in breast-conserving surgery.

ABSTRACT: To compare the performance of margin assessment of specimen mammography (SM) in patients with breast-conserving surgery (BCS) on mobile devices and 5-megapixel (5M) thin film transistor liquid crystal display (TFT-LCD) monitors based on the safety margin for pathologic results.This retrospective study was approved by the institutional review board, and the requirement for informed consent was waived. A total of 105 consecutive breast cancer SM samples from 104 women who underwent BCS were included in the study. The SM were independently reviewed by two radiologists using mobile devices and by two additional radiologists using 5M TFT-LCD monitor. Each reader was asked to measure the shortest distance between the lesion and the lesion margin. The interpretation time was recorded. The sensitivity, specificity, and interobserver agreement were analyzed.In total, 19% (20/105) breast specimens had a positive surgical margin (<1 mm). The mean absolute difference from the pathologic margin was 0.60 ±â€Š0.57 cm and 0.54 ±â€Š0.47 cm using the 5 M TFT-LCD monitor and the mobile device, respectively (without any statistical significance, P = .273). The mean interpretation time was 49.5 and 47.6 s for the 5M TFT-LCD monitor and the mobile device, respectively (P = .012). The pooled sensitivity and specificity were 60% and 74% for 5M TFT-LCD monitor, and 60% and 69% for the mobile device (P = 1.00 and P = .190, respectively). The kappa coefficient indicated moderate agreement for both the displays.The diagnostic performance for margin assessment of SM in BCS patients on mobile devices and 5M TFT-LCD monitors are showed not statistically difference. The findings of the study provide evidence of the benefit of the mobile device for SM interpretation in patients who underwent BCS. However, a large sample size study is warranted before using a mobile device for margin evaluation on SM.The mobile device showed comparable diagnostic performance with 5M TFT-LCD monitor in the evaluation of SM margin in patients with BCS and could be used as a display tool for immediate assessment when a dedicated LCD monitor is unavailable.

First proof-of-concept evaluation of the FUSION-X-US-II prototype for the performance of automated breast ultrasound in healthy volunteers.

PURPOSE: The FUSION-X-US-II prototype was developed to combine 3D-automated breast ultrasound (ABUS) and digital breast tomosynthesis in a single device without decompressing the breast. We evaluated the technical function, feasibility of the examination workflow, image quality, breast tissue coverage and patient comfort of the ABUS device of the new prototype. METHODS: In this prospective feasibility study, the FUSION-X-US-II prototype was used to perform ABUS in 30 healthy volunteers without history of breast cancer. The ABUS images of the prototype were interpreted by a physician with specialization in breast diagnostics. Any detected lesions were measured and classified using BI-RADS® scores. Image quality was rated subjectively by the physician and coverage of the breast was measured. Patient comfort was evaluated by a questionnaire after the examination. RESULTS: One hundred and six scans were performed (61 × CC, 23 × ML, 22 × MLO) in 60 breasts. Image acquisition and processing by the prototype was fast and accurate. Breast coverage by ABUS was approximately 90.8%. Sixteen breast lesions (all benign, classified as BIRADS® 2) were identified. The examination was tolerated by all patients. CONCLUSION: The FUSION-X-US-II prototype allows a rapid ABUS scan with mostly high patient comfort. Technical developments resulted in an improvement of quality and coverage compared to previous prototype versions. The results are encouraging for a test of the prototype in a clinical setting in combination with tomosynthesis.

Breast lesion detection through MammoWave device: Empirical detection capability assessment of microwave images' parameters.

MammoWave is a microwave imaging device for breast lesions detection, which operates using two (azimuthally rotating) antennas without any matching liquid. Images, subsequently obtained by resorting to Huygens Principle, are intensity maps, representing the homogeneity of tissues' dielectric properties. In this paper, we propose to generate, for each breast, a set of conductivity weighted microwave images by using different values of conductivity in the Huygens Principle imaging algorithm. Next, microwave images' parameters, i.e. features, are introduced to quantify the non-homogenous behaviour of the image. We empirically verify on 103 breasts that a selection of these features may allow distinction between breasts with no radiological finding (NF) and breasts with radiological findings (WF), i.e. with lesions which may be benign or malignant. Statistical significance was set at p<0.05. We obtained single features Area Under the receiver operating characteristic Curves (AUCs) spanning from 0.65 to 0.69. In addition, an empirical rule-of-thumb allowing breast assessment is introduced using a binary score S operating on an appropriate combination of features. Performances of such rule-of-thumb are evaluated empirically, obtaining a sensitivity of 74%, which increases to 82% when considering dense breasts only.

The lateral arm device for mammographic breast procedures: overview of its uses, safety, and efficacy.

Introduction: Percutaneous image-guided biopsy is the procedure of choice for diagnosing suspicious abnormalities on breast imaging. Stereotactic, ultrasound, and magnetic resonance imaging are used for image-guided breast biopsies. Stereotactic guidance uses mammography to localize lesions and facilitate placement of a core biopsy needle. The first systems used a vertical-approach needle insertion. The lateral arm device, which is the most recent advancement in stereotactic biopsies and pre-surgical localization allows procedures to be performed using a needle insertion parallel to the compression plate.Areas covered: The lateral arm device was introduced to the market in 2007 and is the first device of its kind. In this article we review the mechanism of this device, the risks and benefits of the device and other the different other modalities utilized to biopsy and localize the breast. We summarize the current literature on this device along with our own experiences utilizing this device.Expert opinion: The lateral arm device has changed the face of stereotactic-guided breast biopsies and localizations by allowing a new approach to perform these procedures. It has improved care to patients by allowing us to get to areas previously not within the biopsy window, decreased biopsy time and increased patient throughput.

Diagnostic accuracy of tomosynthesis-guided vacuum assisted breast biopsy of ultrasound occult lesions.

This study aims to evaluate the diagnostic accuracy of digital breast tomosynthesis-guided vacuum assisted breast biopsy (DBT-VABB) of screening detected suspicious mammographic abnormalities comprising of calcifications, asymmetric densities, architectural distortions and spiculated masses. In this institutionally approved study, a total of 170 (n = 170) DBT-VABB were performed, 153 (90%) were for calcifications, 8 (4.7%) for spiculated mass, 5 (2.9%) for asymmetric density and 4 (2.4%) for architectural distortion. All these lesions were not detected on the corresponding ultrasound. Histopathology results revealed 140 (82.4%) benign, 9 (5.3%) borderline and 21 (12.4%) malignant lesions. The total upgrade rate at surgery was 40% for atypical ductal hyperplasia and 5.9% for ductal carcinoma in-situ. 3.6% discordant benign lesions showed no upgrade. DBT-VABB showed 100% specificity, 91.3% sensitivity and 100% positive predictive value (PPV) for detecting malignant lesions. The negative predictive value (NPV) was 80%. 2 (1.2%) patients had mild complications and 1 (0.6%) had severe pain. Our study showed that DBT-VABB was a safe and reliable method, with high sensitivity, specificity, PPV and NPV in the diagnosis of non-palpable benign and malignant breast lesions. Our data also confirmed the accuracy of DBT-VABB in detecting malignant lesions and we suggest further surgical excision in borderline lesions for a more accurate diagnostic evaluation.

Distribution of pressure on the breast in mammography using flexible and rigid compression plates: implications on patient handling.

BACKGROUND: Breast compression in mammography is important but is a source of discomfort and has been linked to screening non-attendance. Reducing compression has little effect on breast thickness, and likely little effect on image quality, due to force being absorbed in the stiff juxta thoracic area instead of in the central breast. PURPOSE: To investigate whether a flexible compression plate can redistribute force to the central breast and whether this affects perceived pain. MATERIAL AND METHODS: Twenty-eight women recalled from mammography screening were compressed with flexible and rigid plates while retaining force and positioning, 15 in the craniocaudal (CC) view and 13 in the mediolateral oblique (MLO) view. Pressure distribution was continuously measured using pressure sensors. RESULTS: The flexible plate showed greater mean breast pressure in both views: 2.8 versus 2.3 kPa for CC (confidence interval [CI] = 0.2-0.8) and 1.0 versus 0.5 kPa for MLO (CI = 0.2-0.6). The percentage of applied force distributed to the breast was significantly higher with the flexible plate, both on CC (36% vs. 22%, CI = 1-11) and MLO (30% vs. 14%, CI = 4-13). CONCLUSION: The flexible plate redistributes pressure to the central breast, achieving a better compression, particularly in the MLO view, though much applied force is still applied to the juxta thoracic region.

Sistematización de la mastopexia con implantes: Técnica reglada / Systematizing mastopexy with implants: Regulated tecnhique

INTRODUCCIÓN Y OBJETIVO: La mastopexia combinada con implantes que presentamos bajo la denominación Técnica reglada, tiene como finalidad el tratamiento en forma simultánea del volumen y posición de la mama usando implantes de gel de silicona, logrando así el aumento y levantamiento de la mama en un solo tiempo quirúrgico, mediante una sistematización en pasos. MATERIAL Y MÉTODO: Describimos esta sistematización basada en 5 reglas fundamentales y presentamos un estudio sobre pacientes que consultaron por hipotrofia, tejido mamario inconsistente y ptosis mamaria con o sin pérdida masiva de peso, en la Unidad de Cirugía Plástica y Posbariátrica de Caracas, Venezuela, entre 2009 y 2019. RESULTADOS: Practicamos mastopexia por Técnica reglada en 481 pacientes entre 19 y 61 años de edad, en las que el 37.63% (n=181) presentaban condición postbariátrica, 23.91% (n=115) fueron cirugías primarias y 56.13% (n=270) cirugías secundarias. En el 84.62% (n=407) realizamos mastopexia con técnica de pedículo superior, que fue la más frecuentemente utilizada en pacientes sin condición postbariátrica (54%); la mastopexia con técnica de pedículo inferior fue la menos utilizada, en el 2.49% (n=12), y mayormente en pacientes con condición postbariátrica (83.33%). En cuanto al patrón de piel, realizamos cicatrices mínimas en el 84% (n=404) y T invertida en el 16% (n=77). Empleamos implantes de silicona redondos con un rango de volumen de 400 a 500 cc en el 62.37% (n=300). Las complicaciones se dieron en el 14.34% (n=69), siendo las más frecuentes: licuefacción grasa (3.95 %), celulitis (3.53%) y seroma (3.11%), con cirugía de revisión en 3 casos. CONCLUSIONES: El paso a paso de la Técnica reglada ofrece al cirujano una guía práctica para realizar en forma efectiva la combinación de mastopexia con el uso de implantes mamarios, con bajo índice de complicaciones demostrado a través de nuestra casuística

BACKGROUND AND OBJECTIVE: Mastopexy combined with implants that we present with the denomination Regulated technique, aims to simultaneously treat the volume and position of the breast, using silicone gel implants, thus achieving the increase and lifting of the breast in a single surgical time, through a systematization of steps. METHODS: We describe this systematization based on 5 main rules, and present an study in patients who consulted for hypotrophy, inconsistent breast tissue and breast ptosis with or without massive weight loss, carried out in patients who attended the Plastic and Postbariatric Surgery Unit (Caracas, Venezuela) during the period 2009-2019. RESULTS: Mastopexy was performed by Regulated technique in 481 patients between 19 and 61 years old; 37.63% (n=181) had postbariatric condition, 23.91% (n=115) were primary surgeries, 56.13% (n=270) secondary surgeries; 84.62% (n=407) underwent mastopexy with the superior pedicle technique, being the most frequently used in patients without post-bariatric condition (54%), and mastopexy with the inferior pedicle technique was the least used, only in (2.49%) (n=12), and mostly in patients with post-bariatric condition (83.33%). Regarding the skin pattern, minimal scars were made in 84% (n=404) and inverted T in 16% (n=77). Round silicone implants with a volume range of 400 to 500 cc were used in 62.37% (n=300). Complications occurred with an incidence of 14.34% (n=69), the most frequent being: fat liquefaction (3.95%), cellulite (3.53%) and seroma (3.11%), only requiring revision surgery in 3 cases. CONCLUSIONS: The step by step of the Regulated technique offers the surgeon a practical guide to effectively perform the combination of mastopexy with the use of breast implants, with a low rate of complications demonstrated by our clinical series

A prototype Multi-X-ray-source array (MXA) for digital breast tomosynthesis.

The design and testing of a prototype Multi-X-ray-source Array (MXA) for digital breast tomosynthesis is reported. The MXA is comprised of an array of tungsten filament cathodes with focus cup grid-controlled modulation and a common rotating anode housed in a single vacuum envelope. Prototypes consisting of arrays of three-source elements and eleven-source-elements were fabricated and evaluated. The prototype sources demonstrated focal spot sizes of 0.3 mm at 45 kV with 50 mA. Measured x-ray spectra were consistent with the molybdenum anode employed, and the tube output (air kerma) was between 0.6 mGy/100 mAs at 20 kV and 17 mGy/100 mAs at 45 kV with a distance of 100 cm. HVL measurements ranged from 0.5 mm Al at 30 kV to 0.8 mm Al at 45 kV, and x-ray pulse widths were varied from 20 ms to 110 ms at operating frequencies ultimately to be limited by source turn-on/off times of ∼1 ms. Initial results of reconstructed tomographic data are presented.

Saúde em Pauta 01 Bloco3

Programa exibido na Tv Aperipê 6.1 - 18.05.2019

Evaluation of reconstruction algorithms for a stationary digital breast tomosynthesis system using a carbon nanotube X-ray source array.

Breast cancer is the most frequently diagnosed cancer in women worldwide. Digital breast tomosynthesis (DBT), which is based on limited-angle tomography, was developed to solve tissue overlapping problems associated with traditional breast mammography. However, due to the problems associated with tube movement during the process of data acquisition, stationary DBT (s-DBT) was developed to allow the X-ray source array to stay stationary during the DBT scanning process. In this work, we evaluate four widely used and investigated DBT image reconstruction algorithms, including the commercial Feldkamp-Davis-Kress algorithm (FBP), the simultaneous iterative reconstruction technique (SIRT), the simultaneous algebraic reconstruction technique (SART) and the total variation regularized SART (SART-TV) for an s-DBT imaging system that we set up in our own laboratory for studies using a semi-elliptical digital phantom and a rubber breast phantom to determine the most superior algorithm for s-DBT image reconstruction among the four algorithms. Several quantitative indexes for image quality assessment, including the peak signal-noise ratio (PSNR), the root mean square error (RMSE) and the structural similarity (SSIM), are used to determine the best algorithm for the imaging system that we set up. Image resolutions are measured via the calculation of the contrast-to-noise ratio (CNR) and artefact spread function (ASF). The experimental results show that the SART-TV algorithm gives reconstructed images with the highest PSNR and SSIM values and the lowest RMSE values in terms of image accuracy and similarity, along with the highest CNR values calculated for the selected features and the best ASF curves in terms of image resolution in the horizontal and vertical directions. Thus, the SART-TV algorithm is proven to be the best algorithm for use in s-DBT image reconstruction for the specific imaging task in our study.

Structured-light surface scanning system to evaluate breast morphology in standing and supine positions.

Breast shapes are affected by gravitational loads and deformities. Measurements obtained in the standing position may not correlate well with measurements in the supine position, which is more representative of patient position during breast surgery. A dual color 3D surface imaging system capable of scanning patients in both supine and standing positions was developed to evaluate the effect of changes in body posture on breast morphology. The system was evaluated with  breast phantoms to assess accuracy, then tested on ten subjects in three body postures to assess its effectiveness as a clinical tool. The accuracy of the system was within 0.4 mm on average across the model. For the human study, there was no effect of body posture on breast volumes (p value > 0.05), but we observed an effect of completeness of breast scans on body posture (p value < 0.05). Post-hoc tests showed that the supine position and the standing position with hands at the waist differed significantly (p value < 0.05). This study shows that the system can quantitatively evaluate the effect of subject postures, and thereby has the potential to be used to investigate peri-operative changes in breast morphology.

A dedicated phantom design for positron emission mammography performance evaluation.

A standard protocol for performance evaluation of positron emission mammography (PEM) systems has not yet been established. In this work we propose a methodology based on the design of specific phantoms for this imaging modality with component dimensions in accordance with typical breast lesion sizes together with the adaptation of current international protocols designed for clinical and preclinical positron emission tomographs (PET) systems. This methodology was used to evaluate the performance of the Flex Solo II PEM scanner in terms of spatial resolution, uniformity and contrast lesion detectability, recovery coefficients and spill-over ratios. Positron range effects were studied with 18F and 68Ga, which have very different energy spectra. Our results indicate that in-plane spatial resolution of the system is around 3.0 mm and 4.4 mm for 18F and 68Ga, respectively. Lesion detectability tests with sphere diameters between 4 and 10 mm confirmed that the PEM system can resolve all the spheres (hot or cold). Percent contrast values for 18F lie between 6%-38% and 34%-51% for hot- and cold- spheres, respectively; the corresponding intervals for 68Ga are lower, 4%-25% and 32%-44%. Regarding uniformity quantification, the system shows percentage standard deviations within 4.9%-5.7%, while the percent background variability measurements ranged between 6.7% and 10.9% for both radionuclides. Recovery coefficients measured with hot rod diameters between 1.5 and 9 mm, have values between 0.2-1.05 and 0.17-0.69 for 18F and 68Ga, respectively. Spill-over ratios have large values (0.22 in average) for both radionuclides. Our results indicate that the phantoms and the methodology developed in this work can serve as the basis for establishing an image quality protocol for the systematic evaluation of PEM systems, with a potential extension for performance evaluation of dedicated breastPET scanners.

Reflector-guided Localization of Non-palpable Breast Lesions: The First Reported European Evaluation of the SAVI SCOUT® System.

BACKGROUND: Wire-guided localization (WGL) has been the mainstay for localizing non-palpable breast lesions before excision. Due to its limitations, various wireless alternatives have been developed. In this prospective study, we evaluate the role of radiation-free wireless localization using the SAVI SCOUT® localization at a European centre. PATIENTS AND METHODS: This technique was evaluated in a prospective cohort of 20 patients. The evaluation focused on clinical and pathological parameters in addition to patient and physician acceptance. RESULTS: SAVI SCOUT reflectors (n=23) were deployed to localize 22 occult breast lesions and one axillary lymph node in 20 patients. The mean deployment duration was 5.6 min, with a mean distance from the lesion of 0.6 mm. The migration rate was 0% and the mean identification and retrieval time was 25.1 min. In patients undergoing therapeutic excision for malignancy (n=17), only one (5.9%) required reoperation for positive surgical margins. Radiologists and surgeons rated the technique as better than WGL and patient satisfaction was high. CONCLUSION: Our study demonstrates that wireless localization using SAVI SCOUT® is an effective and time-efficient alternative to WGL with excellent physician and patient acceptance.

Characterization of the imaging settings in screening mammography using a tracking and reporting system: A multi-center and multi-vendor analysis.

A tracking and reporting system was developed to monitor radiation dose in X-ray breast imaging. We used our tracking system to characterize and compare the mammographic practices of five breast imaging centers located in the United States and Brazil. Clinical data were acquired using eight mammography systems comprising three modalities: computed radiography (CR), full-field digital mammography (FFDM), and digital breast tomosynthesis (DBT). Our database consists of metadata extracted from 334,234 images. We analyzed distributions and correlations of compressed breast thickness (CBT), compression force, target-filter combinations, X-ray tube voltage, and average glandular dose (AGD). AGD reference curves were calculated based on AGD distributions as a function of CBT. These curves represent an AGD reference for a particular population and system. Differences in AGD and imaging settings were attributed to a combination of factors, such as improvements in technology, imaging protocol, and patient demographics. The tracking system allows the comparison of various imaging settings used in screening mammography, as well as the tracking of patient- and population-specific breast data collected from different populations.

Shift invariant extrema based feature analysis scheme to discriminate the spiculation nature of mammograms.

Since uncontrolled growth of malignant masses introduces uneven shape irregularities and spiculations in the boundary, shape representing shift invariant features are essential to resolve the problem of discrimination. However, ambiguous nature of shape, size, margin, orientation of masses produces imprecise feature values. In this view, a new concept of extrema based feature characterization scheme is proposed for capturing radiating nature of mass morphology. Computation of extrema patterns needs only few algorithmic steps. Beside this, present study employs an automated enhancement procedure to improve the classification accuracy. Experimental results show that extrema characterization reduces the feature redundancy to produce high efficiency in reasonably low time.