Recent Foundation Models have begun to yield remarkable successes across various downstream medical imaging applications. Yet, their potential within the context of multi-view medical image analysis remains largely unexplored. This research aims to investigate the feasibility of leveraging foundation models for predicting breast cancer from multiview mammograms through parameter-efficient transfer learning (PETL). PETL was implemented by inserting lightweight adapter modules into existing pre-trained transformer models. During model training, the parameters of the adapters were updated while the pre-trained weights of the foundation model remained fixed. To assess the model's performance, we retrospectively assembled a dataset of 949 patients, with 470 malignant cases and 479 normal or benign cases. Each patient has four mammograms obtained from two views (CC/MLO) of both the right and left breasts. The large foundation model with 328 million (M) parameters, finetuned with adapters comprising only 3.2M tunable parameters (about 1% of the total model parameters), achieved a classification accuracy of 78.9% ± 1.7%. This performance was competitive but slightly inferior to a smaller model with 36M parameters, finetuned using traditional methods, which attained an accuracy of 80.4% ± 0.9%. The results suggest that while foundation models possess considerable potential, their efficacy in medium-sized datasets and in transitioning from single-view to multi-view image analysis, particularly where reasoning feature relationships across different mammographic views is crucial, can be challenging. This underscores the need for innovative transfer learning approaches to better adapt and generalize foundation models for the complex requirements of multi-view medical image analysis.
This study aims to investigate the effectiveness of a self-supervised deep learning based noise reduction algorithm at improving the detectability of phantom images acquired from the phase-sensitive breast tomosynthesis (PBT) system.
An ACR mammography phantom and three different Contrast Detail (CD) phantoms were used in experiments. Each phantom is 5cm in thickness and fabricated with materials simulating 50% glandular tissue and 50% adipose tissue. The phantoms were imaged by 59kV and 89kV with varying levels of external filtrations. The x-ray exposure was adjusted so that the average glandular dose was consistently to be 1.3 mGy throughout the imaging.
A noise reduction algorithm was applied to the images. The algorithm being evaluated is a state-of-the-art self-supervised single image denoising approach that can prioritize the preservation of fine-grained image structures while performing noise removal.
The contrast-to-noise (CNR) ratio was measured to conduct objective analysis. Additionally, an observer performance study was conducted in which observers were shown the images from each phantom in a randomized order before and after the denoising algorithm was applied. The observers rated the detectability of each image by identifying the minimum perceptible feature.
The results indicate some improvement from the objective studies; however, in the subjective observer studies, no improvement was observed in the detectability of the ACR images, and limited improvement was observed in the detectability of the CD phantom images.
This study aims to investigate the impact of external filtration on image quality and exposure time of an in-line phase-contrast x-ray breast imaging prototype.
A Contrast-Detail phantom is imaged by 59 kV and 89 kV systems with a CCD camera and varying filter thicknesses, ranging from 1.0 mm to 3.3 mm of aluminum. The average glandular radiation dose is set to 1.3 mGy throughout the experiment, regardless of imaging parameters. The Contrast-Detail (CD) curves are generated from the reading results of three experienced observers. The Contrast-to-Noise-Ratio (CNR) is calculated for objective comparisons. The results show that the beam hardening with 1.3 and 2.5 mm aluminum filters in the 59 kV system provides the most desirable CNRs and CD curves, whereas a 3.3 mm aluminum might be a preferable external filtration in the 89 kV system. It can be concluded that the 59 KV beam, filtered by a 1.3 mm aluminum, is a better choice, as it results in comparable image quality and a 35% shorter exposure time. On the other hand, the 89 KV beam filtered by 3.3 mm aluminum results in higher image quality at the expense of slightly increased acquisition time. The prolonged acquisition effect on the image blurring should be evaluated in patient studies where the object is not immobile like imaging phantoms.
X-ray phase sensitive imaging has been employed in the preclinical settings for more than two decades. The advancement in the technology has allowed to potentially translate this innovative imaging technique to the clinical environment. In-line phase sensitive imaging technique has shown promising potential to be used for breast cancer imaging. A high energy phase sensitive breast tomosynthesis (PBT) prototype system based on the inline phase sensitive imaging technique has been developed for the potential imaging in clinical environment. The prototype system incorporates a microfocus x-ray tube and a flat panel detector having a pixel pitch of 70μm. The microfocus x-ray tube has a tungsten (W) anode, Beryllium (Be) output window and a focal spot size that ranges from 18-50μm, depending on the output power. The x-ray tube/detector configuration produces a geometric magnification (M) of 2.2 and acquires 9 projection views within 15 degrees or 30 projection views within 30 degrees in stop-andshoot scanning mode. A single distance phase retrieval scheme method based on the Phase-Attenuation Duality (PAD) principle is applied on the angular projection views. A filtered back-projection operation reconstructs a set of tomogram slices at 1mm incremental depth within the breast along the z-direction. American College of Radiology phantom images demonstrate that both 2D and tomosynthesis images acquired on the prototype system meet the minimum criteria set by the Mammography Quality Standard Act. We have also imaged mastectomy specimens with the PBT prototype system at the University of Utah Huntsman Cancer Hospital. PBT 2D images and tomosynthesis images slices demonstrate image quality comparable to a conventional digital breast tomosynthesis clinical system.
The goal of this study was to perform a characterization study for an in-line phase contrast x-ray imaging prototype with a mid-energy source. Compared to similar prototypes that use high energies, the mid-energy system offers better balancing between the attenuation and phase induced contrasts. An inline phase sensitive prototype acquired all images for this study. The prototype utilizes a microfocus x-ray tube and a flat panel detector, aligned on an optical rail. The source-to-object distance (SOD) was set to 68.58cm while the source-to-image distance (SID) was set to 150.876cm for a magnification of 𝑀 = 2.2. The modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) were calculated for the prototype with source potentials of 60, 90, and 120kV. The oversampled MTF was calculated for each setting. NPS experiments were conducted with a virtual detector set at the SOD. Exposure at the SID was approximately the same for all NPS experiments. The 90 and 120kVp beams were directed through a 2.5mm Al filter, while 60kVp beams were sent through a 1.2mm Al filter. Results indicate that 60kV imaging yields lower amplitude noise than high energy imaging, while maintaining the same resolving power. The cutoff frequency for each source potential was approximately 14 line pairs per mm (lp/mm). The DQE(0) for 60kV, 90kV, and 120kV were 0.757, 0.564, and 0.571 respectively. The study confirmed the hypothesis that 60kVp phase sensitive x-ray imaging yields a higher DQE than those found at 90 and 120kVp.
Mammographic studies have always been a challenge in women with large or dense breasts. A contrast-detail (CD) phantom and an American College of Radiology (ACR) accredited phantom are used in this study to compare the detectability of the mid-energy phase-contrast x-ray imaging system and conventional x-ray imaging mode among women with hyper-glandular breast tissue. Insert wax from ACR phantom and the contrast-detail test pattern are both inserted between two 70/30 glandular-adipose tissue equivalent plates, to simulate a 5 cm thick compressed dense breast. Both phantoms are imaged by the two modalities: (a): the x-ray bench-top imaging system in contact mode, similar to conventional mammography, operated at 35kV with 0.5 mm aluminum filter, and (b): the mid-energy in-line phasesensitive prototype, which is operated at 59kV, 1.3 mm aluminum filter and the magnification factor of 2.5. Both imaging systems applied an average glandular radiation dose of 1.6 mGy. The results show that the image of ACR phantom which is acquired by mid-energy phase-contrast imaging system reveals more embedded objects within the phantom compare to conventional imaging system under the similar average glandular dose. The contrast-detail curves for CD phantom, obtained from two imaging prototypes, confirm the superior detectability of phase contrast imaging system. Therefore, this preliminary experiment demonstrates that mid-energy phase-contrast x-ray imaging system exceeds the performance of conventional mammography in hyper-glandular breast tissue at the equal level of radiation dose to the patients.
The objectives of this study were to develop and evaluate a breast tissue equivalent phantom that can be used for dual purposes, conventional x-ray imaging and ultrasonography. This phantom was designed based on the prototype of an intralipid-gel soft tissue mimicking phantom used for laser photothermal therapy. The glandularities and the densities of the phantom can be adjusted by modifying the ratio of intralipid and other ingredients and adding fiber powders. An adipose tissue phantom and a glandular tissue phantom were firstly developed and phantoms of different glandularities were further developed through mixing different weight proportions of adipose and glandular. To validate the properties of the phantom for the applications of x-ray imaging techniques, three methods were employed: (1) the compositions of the elements contained in the phantoms were estimated through calculations; (2) the x-ray mass attenuation coefficients of the phantom were calculated based on the elemental compositions; (3) the x-ray photon energies deposit in the phantoms with different glandularities were simulated using Geant4 Simulation Tool Kit. The results showed high agreements with the real breast tissues at corresponding breast glandularities. For the application in ultrasonography, the elasticity of the phantom was determined by measuring the value of Young’s modulus and the value of 39 ± 10 kPa indicated the satisfactory of the requirement of being used as phantom for ultrasound imaging. Therefore, the phantoms developed in this study potentially provided a solution of dualpurpose breast tissue mimicking phantom in the needs of different level of glandularity.
The objective of this study was to demonstrate the capability of the high-energy in-line phase contrast imaging in detecting the breast tumors which are undetectable by conventional x-ray imaging but detectable by ultrasound. Experimentally, a CIRS multipurpose breast phantom with heterogeneous 50% glandular and 50% adipose breast tissue was imaged by high-energy in-line phase contrast system, conventional x-ray system and ultrasonography machine. The high-energy in-line phase contrast projection was acquired at 120 kVp, 0.3 mAs with the focal spot size of 18.3 μm. The conventional x-ray projection was acquired at 40 kVp, 3.3 mAs with the focal spot size of 22.26 μm. Both of the x-ray imaging acquisitions were conducted with a unique mean glandular dose of 0.08 mGy. As the result, the high-energy in-line phase contrast system was able to detect one lesion-like object which was also detected by the ultrasonography. This object was spherical shape with the length of about 12.28 mm. Also, the conventional x-ray system was not able to detect any objects. This result indicated the advantages provided by high-energy in-line phase contrast over conventional x-ray system in detecting lesion-like object under the same radiation dose. To meet the needs of current clinical strategies for high-density breasts screening, breast phantoms with higher glandular densities will be employed in future studies.
The objective of this study is to demonstrate the potential of using the High-energy in-line phase contrast x-ray imaging to detect lesions that are indistinguishable by conventional x-ray mammography but are detectable by supplemental ultrasound screening within dense breasts. For this study, a custom-made prototype x-ray/ultrasound dualmodality phantom that mimics dense breast is created to include embedded carbon fiber disks with multiple diameters and thicknesses. The phase contrast image is acquired using a prototype at 120kVp, 67μA, exposure time of 16.7sec and focal spot size of 18.3μm with average glandular dose (AGD) of 0.3mGy under a geometric magnification of 2.48. The conventional x-ray image is acquired with a bench top system operating at 40kVp, 300μA, exposure time of 50sec and same AGD. The results demonstrate that conventional x-ray imaging is unable to detect any of the carbon fiber disks, while phase contrast imaging and ultrasonography are able to detect most or all of the disks under the applied experimental conditions. These results illustrate phase contrast imaging is capable of detecting targets in a dual-modality phantom which simulates lesions in dense breast tissue, when the simulated lesions are not distinguishable by conventional mammography. Therefore mammographic screening with phase contrast technique could eventually replace both x-ray and ultrasonography for screening detection of small lesions with microcalcification in dense breasts where pathologic lesions are masked due to highly glandular tissue. These results encourage further investigation using high glandular density phantoms to further evaluate the effectiveness of phase contrast imaging as a single modality test, which combines the advantages of both x-ray and ultrasound imaging in cancer screening of patients with dense breasts.
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