High-Resolution Fluorodeoxyglucose Positron Emission Tomography with Compression ("Positron Emission Mammography") is Highly Accurate in Depicting Primary Breast Cancer

Radiotracer Innovations in Breast Cancer Imaging: A Review of Recent Progress

This review focuses on the pivotal role of radiotracers in breast cancer imaging, emphasizing their importance in accurate detection, staging, and treatment monitoring. Radiotracers, labeled with radioactive isotopes, are integral to various nuclear imaging techniques, including positron emission tomography (PET) and positron emission mammography (PEM). The most widely used radiotracer in breast cancer imaging is 18F-fluorodeoxyglucose (18F-FDG), which highlights areas of increased glucose metabolism, a hallmark of many cancer cells. This allows for the identification of primary tumors and metastatic sites and the assessment of tumor response to therapy. In addition to 18F-FDG, this review will explore newer radiotracers targeting specific receptors, such as estrogen receptors or HER2, which offer more personalized imaging options. These tracers provide valuable insights into the molecular characteristics of tumors, aiding in tailored treatment strategies. By integrating radiotracers into breast cancer management, clinicians can enhance early disease detection, monitor therapeutic efficacy, and guide interventions, ultimately improving patient outcomes. Ongoing research aimed at developing more specific and sensitive tracers will also be highlighted, underscoring their potential to advance precision medicine in breast cancer care.

Crystal scatter effects in a large-area dual-panel Positron Emission Mammography system

Positron Emission Mammography (PEM) is a valuable molecular imaging technique for breast studies using pharmaceuticals labeled with positron emitters and dual-panel detectors. PEM scanners normally use large scintillation crystals coupled to sensitive photodetectors. Multiple interactions of the 511 keV annihilation photons in the crystals can result in event mispositioning leading to a negative impact in radiopharmaceutical uptake quantification. In this work, we report the study of crystal scatter effects of a large-area dual-panel PEM system designed with either monolithic or pixelated lutetium yttrium orthosilicate (LYSO) crystals using the Monte Carlo simulation platform GATE. The results show that only a relatively small fraction of coincidences (~20%) arise from events where both coincidence photons undergo single interactions (mostly through photoelectric absorption) in the crystals. Most of the coincidences are events where at least one of the annihilation photons undergoes a chain of Compton scatterings: approximately 79% end up in photoelectric absorption while the rest (<1%) escape the detector. Mean positioning errors, calculated as the distance between first hit and energy weighted (assigned) positions of interaction, were 1.70 mm and 1.92 mm for the monolithic and pixelated crystals, respectively. Reconstructed spatial resolution quantification with a miniDerenzo phantom and a list mode iterative reconstruction algorithm shows that, for both crystal types, 2 mm diameter hot rods were resolved, indicating a relatively small effect in spatial resolution. A drastic reduction in peak-to-valley ratios for the same hot-rod diameters was observed, up to a factor of 14 for the monolithic crystals and 7.5 for the pixelated ones.

Clinical Applications of Dedicated Breast Positron Emission Tomography

Breast-specific positron imaging systems provide higher sensitivity than whole-body PET for breast cancer detection. The clinical applications for breast-specific positron imaging are similar to breast MRI including preoperative local staging and neoadjuvant therapy response assessment. Breast-specific positron imaging may be an alternative for patients who cannot undergo breast MRI. Further research is needed in expanding the field-of-view for posterior breast lesions, increasing biopsy capability, and reducing radiation dose. Efforts are also necessary for developing appropriate use criteria, increasing availability, and advancing insurance coverage.

Multiparametric Approach to Breast Cancer With Emphasis on Magnetic Resonance Imaging in the Era of Personalized Breast Cancer Treatment

ABSTRACT

A multiparametric approach to breast cancer imaging offers the advantage of integrating the diverse contributions of various parameters. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is the most important MRI sequence for breast imaging. The vascularity and permeability of lesions can be estimated through the use of semiquantitative and quantitative parameters. The increased use of ultrafast DCE-MRI has facilitated the introduction of novel kinetic parameters. In addition to DCE-MRI, diffusion-weighted imaging provides information associated with tumor cell density, with advanced diffusion-weighted imaging techniques such as intravoxel incoherent motion, diffusion kurtosis imaging, and time-dependent diffusion MRI opening up new horizons in microscale tissue evaluation. Furthermore, T2-weighted imaging plays a key role in measuring the degree of tumor aggressiveness, which may be related to the tumor microenvironment. Magnetic resonance imaging is, however, not the only imaging modality providing semiquantitative and quantitative parameters from breast tumors. Breast positron emission tomography demonstrates superior spatial resolution to whole-body positron emission tomography and allows comparable delineation of breast cancer to MRI, as well as providing metabolic information, which often precedes vascular and morphological changes occurring in response to treatment. The integration of these imaging-derived factors is accomplished through multiparametric imaging. In this article, we explore the relationship among the key imaging parameters, breast cancer diagnosis, and histological characteristics, providing a technical and theoretical background for these parameters. Furthermore, we review the recent studies on the application of multiparametric imaging to breast cancer and the significance of the key imaging parameters.

Dedicated phantom tools using traceable 68Ge/68Ga point-like sources for dedicated-breast PET and positron emission mammography scanners

Since the early 2000s, many types of positron emission tomography (PET) scanners dedicated to breast imaging for the diagnosis of breast cancer have been introduced. However, conventional performance evaluation methods developed for whole-body PET scanners cannot be used for such devices. In this study, we developed phantom tools for evaluating the quantitative accuracy of positron emission mammography (PEM) and dedicated-breast PET (dbPET) scanners using novel traceable point-like ⁶⁸Ge/⁶⁸ Ga sources. The PEM phantom consisted of an acrylic cube (100 × 100 × 40 mm) and three point-like sources. The dbPET phantom comprised an acrylic cylinder (ø100 × 100 mm) and five point-like sources. These phantoms were used for evaluating the fundamental responses of clinical PEM and dbPET scanners to point-like inputs in a medium. The results showed that reasonable recovery values were obtained based on region-of-interest analyses of the reconstructed images. The developed phantoms using traceable ⁶⁸Ge/⁶⁸ Ga point-like sources were useful for evaluating the physical characteristics of PEM and dbPET scanners. Thus, they offer a practical, reliable, and universal measurement scheme for evaluating various types of PET scanners using common sets of sealed sources.

ACR Appropriateness Criteria® Evaluation of Nipple Discharge: 2022 Update

The type of nipple discharge dictates the appropriate imaging study. Physiologic nipple discharge is common and does not require diagnostic imaging. Pathologic nipple discharge in women, men, and transgender patients necessitates breast imaging. Evidence-based guidelines were used to evaluate breast imaging modalities for appropriateness based on patient age and gender. For an adult female or male 40 years of age or greater, mammography or digital breast tomosynthesis (DBT) is performed initially. Breast ultrasound is usually performed at the same time with rare exception. For males or females 30 to 39 years of age, mammography/DBT or breast ultrasound is performed based on institutional preference and individual patient considerations. For young women less than 30 years of age, ultrasound is performed first with mammography/DBT added if there are suspicious findings or if the patient is at elevated lifetime risk for developing breast cancer. There is a high incidence of breast cancer in males with pathologic discharge. Men 25 years and older should be evaluated using mammography/DBT and ultrasound added when indicted. In transfeminine (male-to-female) patients, mammography/DBT and ultrasound are useful due to the increased incidence of breast cancer. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Breast-Specific Gamma Imaging: An Added Value in the Diagnosis of Breast Cancer, a Systematic Review

Simple Summary

Breast-specific gamma imaging represents an emergent instrument for breast cancer detection. We selected on Medline articles published from 1995 to 2022 that compare various imaging modalities with breast-specific gamma imaging. The aim of this paper was to assess if this imaging method is a more valuable choice in detecting breast malignant lesions compared to morphological counterparts such mammography, ultrasound, and magnetic resonance imaging in terms of specificity, sensibility and positive and negative predictive value. At the cost of a major radiology burden, breast-specific gamma imaging is more specific, with a sensibility comparable to magnetic resonance imaging and higher than ultrasonography and mammography.

Abstract

Purpose: Breast cancer is the most common solid tumor and the second highest cause of death in the United States. Detection and diagnosis of breast tumors includes various imaging modalities, such as mammography (MMG), ultrasound (US), and contrast-enhancement MRI. Breast-specific gamma imaging (BSGI) is an emerging tool, whereas morphological imaging has the disadvantage of a higher absorbed dose. Our aim was to assess if this imaging method is a more valuable choice in detecting breast malignant lesions compared to morphological counterparts. Methods: research on Medline from 1995 to June 2022 was conducted. Studies that compared at least one anatomical imaging modality with BSGI were screened and assessed through QUADAS2 for risk of bias and applicability concerns assessment. Sensitivity, specificity, positive and negative predictive value (PPV and NPV) were reported. Results: A total of 15 studies compared BSGI with MMG, US, and MRI. BSGI sensitivity was similar to MRI, but specificity was higher. Specificity was always higher than MMG and US. BSGI had higher PPV and NPV. When used for the evaluation of a suspected breast lesion, the overall sensitivity was better than the examined overall sensitivity when BSGI was excluded. Risk of bias and applicability concerns domain showed mainly low risk of bias. Conclusion: BSGI is a valuable imaging modality with similar sensitivity to MRI but higher specificity, although at the cost of higher radiation burden.

Evaluation of the Pink Luminous Breast LED-Based Technology Device as a Screening Tool for the Early Detection of Breast Abnormalities

Breast cancer is the leading cause of sex-specific female cancer deaths in the United States. Detection at earlier stages contributes to decreasing the mortality rate. The mammogram is the "Gold Standard" for breast cancer screening with an estimated sensitivity of 86.9% and a specificity of 88.9%. However, these values are negatively affected by the breast density considered a risk factor for developing breast cancer. Herein, we validate the novel LED-based medical device Pink Luminous Breast (PLB) by comparison with the mammogram using a double blinded approach. The PLB works by emitting a LED red light with a harmless spectrum of 640-800 nanometers. This allows the observation of abnormalities represented by dark or shadow areas. In this study, we evaluated the sensitivity and specificity of the PLB device as a screening tool for the early detection of breast abnormalities. Our results show that the PLB device has a high sensitivity (89.6%) and specificity (96.4%) for detecting breast abnormalities comparable to the adjusted mammogram values: 86.3 and 68.9%, respectively. The percentage of presence of breast density was 78.2% using PLB vs. 72.9% with the mammogram. Even with higher findings of breast density, the PLB is still capable of detecting 9.4% of calcifications compared to 6.2% in mammogram results and the reported findings for cysts, masses, or tumor-like abnormalities was higher using the PLB (6.5%) than the mammogram (5.6%). A 100% of the participants felt comfortable using the device without feeling pain or discomfort during the examination with 100% acceptability. The PLB positive validation shows its potential for routine breast screening at non-clinical settings. The PLB provides a rapid, non-invasive, portable, and easy-to-use tool for breast screening that can complement the home-based breast self-examination technique or the clinical breast examination. In addition, the PLB can be conveniently used for screening breasts with surgical implants. PLB provides an accessible and painless breast cancer screening tool. The PLB use is not intended to replace the mammogram for breast screening but rather to use it as an adjunct or complemental tool as part of more efficient earlier detection strategies contributing to decrease mortality rates.

Clustering subtypes of breast cancer by combining immunohistochemistry profiles and metabolism characteristics measured using FDG PET/CT

BACKGROUND

The aim of this study was to investigate the effect of combining immunohistochemical profiles and metabolic information to characterize breast cancer subtypes.

METHODS

This retrospective study included 289 breast tumors from 284 patients who underwent preoperative 18 F-fluorodeoxyglucose (FDG) positron emission tomography/ computed tomography (PET/CT). Molecular subtypes of breast cancer were classified as Hormonal, HER2, Dual (a combination of both Hormonal and HER2 features), and triple-negative (TN). Histopathologic findings and immunohistochemical results for Ki-67, EGFR, CK 5/6, and p53 were also analyzed. The maximum standardized uptake value (SUV) measured from FDG PET/CT was used to evaluate tumoral glucose metabolism.

RESULTS

Overall, 182, 24, 47, and 36 tumors were classified as Hormonal, HER2, Dual, and TN subtypes, respectively. Molecular profiles of tumor aggressiveness and the tumor SUV revealed a gradual increase from the Hormonal to the TN type. The tumor SUV was significantly correlated with tumor size, expression levels of p53, Ki-67, and EGFR, and nuclear grade (all p < 0.001). In contrast, the tumor SUV was negatively correlated with the expression of estrogen receptors (r = - 0.234, p < 0.001) and progesterone receptors (r = - 0.220, p < 0.001). Multiple linear regression analysis revealed that histopathologic markers explained tumor glucose metabolism (adjusted R-squared value 0.238, p < 0.001). Tumor metabolism can thus help define breast cancer subtypes with aggressive/adverse prognostic features.

CONCLUSIONS

Metabolic activity measured using FDG PET/CT was significantly correlated with the molecular alteration profiles of breast cancer assessed using immunohistochemical analysis. Combining molecular markers and metabolic information may aid in the recognition and understanding of tumor aggressiveness in breast cancer and be helpful as a prognostic marker.

Performance of dedicated breast positron emission tomography in the detection of small and low-grade breast cancer

PURPOSE

This study compares the sensitivity of dedicated breast positron emission tomography (DbPET) and whole body positron emission tomography (WBPET) in detecting invasive breast cancer based on tumor size and biology. Further, we explored the relationship between maximum standardized uptake value (SUVmax) of DbPET and biological features of the tumor.

METHODS

A total of 639 invasive breast cancer lesions subjected to both DbPET and WBPET before surgery, between January 2016 and May 2019, were included in the study. The sensitivity of DbPET and WBPET in detection and the biology of the tumor according to the clinicopathological features were retrospectively evaluated.

RESULTS

The overall sensitivity of DbPET was higher than that of WBPET (91.4% vs. 80.3%, p < 0.001). Subcentimetric tumors were significant (80.9% vs. 54.3%, p < 0.001). Regardless of the nuclear grade, DbPET could detect more lesions than WBPET. The SUVmax was positively correlated with tumor size (R = 0.395, p < 0.001) and the nuclear grade (p < 0.001). Luminal A-like breast cancer had significantly lower SUVmax values than the other subtypes (p < 0.001).

CONCLUSIONS

DbPET is superior to WBPET in the detection of subcentimetric, low-grade breast cancers. Further, by using SUVmax, DbPET can distinguish luminal A-like breast cancer from the other subtypes.

Positron Emission Mammography (PEM) in the diagnosis of breast cancer: A systematic review and economic evaluation

Background: Positron Emission Mammography (PEM) is an imaging technique which is increasing focuses on imaging the chest instead of imaging the whole body. The aim of this study was to conduct a systematic review of the clinical efficacy and coste-ffectiveness of PEM technology, as compared with PET, as a diagnostic method used for breast cancer patients.

Methods: The present study was a Health Technology Assessment (HTA), which was conducted via a systematic review of clinical efficacy and cost-effectiveness of the methods based on domestic evidence. To evaluate the efficacy of the PEM diagnostic method, as compared with PET, we used efficacy indices, including Sensitivity, Specificity, Accuracy, PPV, and NPV. The required data were collected through a meta-analysis of studies published in electronic databases from 1990 to 2016. In addition, direct costs in both methods were estimated and finally, a cost-effectiveness analysis was performed using the results of the study. Also, a one-way sensitivity analysis was performed to examine the effects of parameters’ uncertainty in the model. In this study, we used STATA software to integrate the results of studies with similar parameters.

Results: A total of 722 cases (N) were obtained from the five final studies. The results of the meta-analysis performed on the collected data showed that the two methods were identical in terms of the Specificity and PPV parameters. However, as to Sensitivity, NPV, and Accuracy parameters, the PEM method was superior to the PET for diagnosis of primary breast cancer. The total cost of using PEM and PET was $1737385.7 and $1940903.5, respectively, and the cost of a one-time scan (cost per unit) using PEM and PET devices was $86.82 and $157.63, respectively. As compared with the PET method, the use of the PEM diagnostic method for diagnosis of breast cancer was cost-effective in terms of all the five studied parameters (it was definitely cost-effective for four parameters and was also considered as cost-effective for another index, since ICER was below the threshold).

Conclusion: The results showed that the use of PEM technology for the diagnosis of primary breast cancer is more cost-effective than PET technology; thus, due to the wide range of PET technology in different fields, it is recommended that this method should be used in other areas of priority.

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.

Impact of Using Uniform Attenuation Coefficients for Heterogeneously Dense Breasts in a Dedicated Breast PET/X-ray Scanner

We investigated PET image quantification when using a uniform attenuation coefficient (μ) for attenuation correction (AC) of anthropomorphic density phantoms derived from high-resolution breast CT scans. A breast PET system was modeled with perfect data corrections except for AC. Using uniform μ for AC resulted in quantitative errors roughly proportional to the difference between μ used in AC (μ _AC) and local μ, yielding approximately ± 5% bias, corresponding to the variation of μ for 511 keV photons in breast tissue. Global bias was lowest when uniform μ _AC was equal to the phantom mean μ (μ _mean). Local bias in 10-mm spheres increased as the sphere μ deviated from μ _mean, but remained only 2-3% when the μ _sphere was 6.5% higher than μ _mean. Bias varied linearly with and was roughly proportional to local μ mismatch. Minimizing local bias, e.g., in a small sphere, required the use of a uniform μ value between the local μ and the μ _mean. Thus, biases from using uniform-μ AC are low when local μ _sphere is close to μ _mean. As the μ _sphere increasingly differs from the phantom μ _mean, bias increases, and the optimal uniform μ is less predictable, having a value between μ _sphere and the phantom μ _mean.

New advance in breast cancer pathology and imaging

The improvement of knowledge concerning the pathology of breast cancer could provide the rationale for the development of new imaging diagnostic protocols. Indeed, as for the microcalcifications, new histopathological markers can be used as target for in vivo early detection of breast cancer lesions by using molecular imaging techniques such as positron emission tomography. Specifically, the mutual contribution of these medical specialties can ‘nourish’ the dream of a personalized medicine that takes into account the intrinsic variability of breast cancer. In this review, we report the main discoveries concerning breast cancer pathology highlighting the possible cooperation between the departments of anatomic pathology and imaging diagnostics.

Redefining the sensitivity of screening mammography: A review

From its inception, screening mammography has enjoyed a perceived level of sensitivity that is inconsistent with available evidence. The original data that imparted erroneous beliefs about sensitivity were based on a variety of misleading definitions and approaches, such as the inclusion of palpable tumors, using the inverse of interval cancer rates (often tied to an arbitrary 12 month interval), and quoting prevalence screen sensitivity wherein tumors are larger than those found on incidence screens. This review addresses the background for the overestimation of mammographic sensitivity, and how a major adjustment in our thinking is overdue now that multi-modality imaging allows us to determine real time mammographic sensitivity. Although a single value for mammographic sensitivity is disingenuous, given the wide range based on background density, it is important to realize that a sensitivity gap between belief and reality still exists in the early detection of breast cancer using mammography alone, in spite of technologic advances. Failure to recognize this gap diminishes the acceptance of adjunct methods of breast imaging that greatly complement detection rates.

Overview of Breast Cancer Screening and Diagnosis

Screening mammography saves lives. The mainstay of screening has been mammography. Multiple alternative options, however, for supplemental imaging are now available. Some are just improved anatomic delineation whereas others include physiology added to anatomy. A third group (molecular imaging) is purely physiologic. This article describes and compares the available options and for which patient populations they should be used.

Use of Breast-Specific PET Scanners and Comparison with MR Imaging

The goals of this article are to discuss the role of breast-specific PET imaging of women with breast cancer, compare the clinical performance of positron emission mammography (PEM) and MR imaging for current indications, and provide recommendations for when women should undergo PEM instead of breast MR imaging.

Newly-Developed Positron Emission Mammography (PEM) Device for the Detection of Small Breast Cancer

Positron emission mammography (PEM) has higher detection sensitivity for breast cancer compared with whole-body positron emission tomography (PET) due to higher spatial resolution. We have developed a new PEM device with high resolution over a wide field of view. This PEM device comprises novel scintillation crystals, praseodymium-doped lutetium aluminum garnet (Pr:LuAG). In the present study, the clinical use of the newly developed PEM for the detection of small breast cancer was compared with that of the conventional PET-computed tomography (PET/CT). Eighty-two patients with breast cancer less than 20 mm (UICC T1) participated in this study, including 23 patients with T1a or T1b breast cancer (less than 10 mm). Histologically-proved lesions were examined by PET/CT and PEM on the same day after injection of [¹⁸F]fluoro-2-deoxy-2-fluoro-D-glucose ([¹⁸F]FDG), a marker of glycolytic activity. The newly developed PEM showed better sensitivity of cancer detection compared with PET/CT especially in case of the small T1a or T1b lesions. Moreover, when the conventional PET/CT and new PEM were combined, the detection sensitivity with [¹⁸F]FDG molecular imaging for T1 (N = 82) and T1a plus T1b breast cancer (N = 23) were 90% and 70%, respectively. The uptake of [¹⁸F]FDG was proportional to the histological malignancy of breast cancer. Using the newly-developed PEM with [¹⁸F]FDG, we are able to identify and characterize exactly the small breast tumors less than 10 mm in combination with the conventional PET/CT. These data indicate that PEM and PET/CT are synergic and complementary for the detection of small breast cancer.

Developments in Breast Imaging: Update on New and Evolving MR Imaging and Molecular Imaging Techniques

This article reviews new developments in breast imaging. There is growing interest in creating a shorter, less expensive MR protocol with broader applicability. There is an increasing focus on and consideration for the additive impact that functional analysis of breast pathology have on identifying and characterizing lesions. These developments apply to MR imaging and molecular imaging. This article reviews evolving breast imaging techniques with attention to strengths, weaknesses, and applications of these approaches. We aim to give the reader familiarity with the state of current developments in the field and to increase awareness of what to expect in breast imaging.

ACR Appropriateness Criteria® Evaluation of Nipple Discharge

Appropriate imaging evaluation of nipple discharge depends the nature of the discharge. Imaging is not indicated for women with physiologic nipple discharge. For evaluation of pathologic nipple discharge, multiple breast imaging modalities are rated for evidence-based appropriateness under various scenarios. For women age 40 or older, mammography or digital breast tomosynthesis (DBT) should be the initial examination. Ultrasound is usually added as a complementary examination, with some exceptions. For women age 30 to 39, either mammogram or ultrasound may be used as the initial examination on the basis of institutional preference. For women age 30 or younger, ultrasound should be the initial examination, with mammography/DBT added when ultrasound shows suspicious findings or if the patient is predisposed to developing breast cancer. For men age 25 or older, mammography/DBT should be performed initially, with ultrasound added as indicated, given the high incidence of breast cancer in men with pathologic nipple discharge. Although MRI and ductography are not usually appropriate as initial examinations, each may be useful when the initial standard imaging evaluation is negative. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Ultrasound Imaging Technologies for Breast Cancer Detection and Management: A Review

Ultrasound imaging is a commonly used modality for breast cancer detection and diagnosis. In this review, we summarize ultrasound imaging technologies and their clinical applications for the management of breast cancer patients. The technologies include ultrasound elastography, contrast-enhanced ultrasound, 3-D ultrasound, automatic breast ultrasound and computer-aided detection of breast ultrasound. We summarize the study results seen in the literature and discuss their future directions. We also provide a review of ultrasound-guided, breast biopsy and the fusion of ultrasound with other imaging modalities, especially magnetic resonance imaging (MRI). For comparison, we also discuss the diagnostic performance of mammography, MRI, positron emission tomography and computed tomography for breast cancer diagnosis at the end of this review. New ultrasound imaging techniques, ultrasound-guided biopsy and the fusion of ultrasound with other modalities provide important tools for the management of breast patients.

Awareness and current knowledge of breast cancer

Breast cancer remains a worldwide public health dilemma and is currently the most common tumour in the globe. Awareness of breast cancer, public attentiveness, and advancement in breast imaging has made a positive impact on recognition and screening of breast cancer. Breast cancer is life-threatening disease in females and the leading cause of mortality among women population. For the previous two decades, studies related to the breast cancer has guided to astonishing advancement in our understanding of the breast cancer, resulting in further proficient treatments. Amongst all the malignant diseases, breast cancer is considered as one of the leading cause of death in post menopausal women accounting for 23% of all cancer deaths. It is a global issue now, but still it is diagnosed in their advanced stages due to the negligence of women regarding the self inspection and clinical examination of the breast. This review addresses anatomy of the breast, risk factors, epidemiology of breast cancer, pathogenesis of breast cancer, stages of breast cancer, diagnostic investigations and treatment including chemotherapy, surgery, targeted therapies, hormone replacement therapy, radiation therapy, complementary therapies, gene therapy and stem-cell therapy etc for breast cancer.

Recent Advances in Breast-Specific Imaging

Background

Imaging the breast is a vital component not only for breast cancer screening, but also for diagnosis, evaluation, treatment, and follow-up of patients with breast cancer.

Methods

The author reviews recent advances and also provides her personal experience in describing the status of digital mammography, computer-aided detection, dedicated magnetic resonance imaging (MRI), and positron-emission mammography for evaluating the breast.

Results

Full-field digital mammography is superior to standard mammography in women under 50 years of age and in those with dense breasts. Computer-aided detection assists inexperienced mammographers and enhances detection of microcalcifications in dense breasts. Breast MRI is useful in preoperative evaluation, clarification of indeterminate mammograms, and follow-up of BRCA mutation carriers. The specificity of MRI remains problematic, however. Positron-emission mammography promises enhanced detection of ductal carcinoma in situ (DCIS), even when not associated with microcalcifications, and should aid surgical planning.

Conclusions

These four significant advances in breast imaging have all improved the sensitivity of detecting breast abnormalities. Cost issues, however, may limit the widespread application of these advances.

Higher breast cancer conspicuity on dbPET compared to WB-PET/CT

OBJECTIVES

The purpose of this study was to evaluate lesion detectability of a dedicated breast positron-emission tomography (dbPET) scanner for breast cancers with an updated reconstruction mode, comparing it to whole-body positron-emission tomography/computed tomography (WB-PET/CT).

MATERIALS AND METHODS

A total of 179 histologically-proven breast cancer lesions in 150 females who underwent both WB-PET/CT and dbPET with ¹⁸F-fluorodeoxyglucose were retrospectively analyzed. The patient/breast/lesion-based sensitivities based on visual analysis were compared between dbPET and WB-PET/CT. For lesions visible on both PET images, SUVmax values of the tumors were measured, and tumor-to-background ratios (T/B ratios) of SUVmax were compared between the two scans. Subgroup analyses according to clinical tumor stage, histopathology and histological grade were also performed.

RESULTS

Patient/breast/lesion-based sensitivities were 95%, 95%, and 92%, respectively, for dbPET, and 95%, 94%, and 88%, respectively, for WB-PET/CT. Mean±standard deviation SUVmax values of FDG-avid tumors were 13.0±9.7 on dbPET and 6.4±4.8 on WB-PET. T/B ratios were also significantly higher in dbPET than in WB-PET/CT (8.1±7.1 vs. 5.1±4.5). In the subgroup analysis, no significant differences in sensitivities between dbPET and WB-PET/CT were found. However, T/B ratios of dbPET were significantly higher than those of WB-PET/CT in cT1c, cT2, cT3, invasive cancer, invasive carcinoma of no special type, mucinous carcinoma and Grades 1-3.

CONCLUSION

No significant differences in sensitivities were identified between dbPET using an updated reconstruction mode and WB-PET/CT; however, T/B ratios of dbPET were significantly higher than those of WB-PET/CT, indicating higher tumor conspicuity on dbPET.

Performance evaluation of a high resolution dedicated breast PET scanner

PURPOSE

Early stage breast cancers may not be visible on a whole-body PET scan. To overcome whole-body PET limitations, several dedicated breast positron emission tomography (DbPET) systems have emerged nowadays aiming to improve spatial resolution. In this work the authors evaluate the performance of a high resolution dedicated breast PET scanner (Mammi-PET, Oncovision).

METHODS

Global status, uniformity, sensitivity, energy, and spatial resolution were measured. Spheres of different sizes (2.5, 4, 5, and 6 mm diameter) and various 18 fluorodeoxyglucose ((18)F-FDG) activity concentrations were randomly inserted in a gelatine breast phantom developed at our institution. Several lesion-to-background ratios (LBR) were simulated, 5:1, 10:1, 20:1, 30:1, and 50:1. Images were reconstructed using different voxel sizes. The ability of experienced reporters to detect spheres was tested as a function of acquisition time, LBR, sphere size, and matrix reconstruction voxel size. For comparison, phantoms were scanned in the DbPET camera and in a whole body PET (WB-PET). Two patients who just underwent WB-PET/CT exams were imaged with the DbPET system and the images were compared.

RESULTS

The measured absolute peak sensitivity was 2.0%. The energy resolution was 24.0% ± 1%. The integral and differential uniformity were 10% and 6% in the total field of view (FOV) and 9% and 5% in the central FOV, respectively. The measured spatial resolution was 2.0, 1.9, and 1.7 mm in the radial, tangential, and axial directions. The system exhibited very good detectability for spheres ≥4 mm and LBR ≥10 with a sphere detection of 100% when acquisition time was set >3 min/bed. For LBR = 5 and acquisition time of 7 min the detectability was 100% for spheres of 6 mm and 75% for spheres of 5, 4, and 2.5 mm. Lesion WB-PET detectability was only comparable to the DbPET camera for lesion sizes ≥5 mm when acquisition time was >3 min and LBR > 10.

CONCLUSIONS

The DbPET has a good performance for its clinical use and shows an improved resolution and lesion detectability of small lesions compared to WB-PET.

Can positron emission mammography help to identify clinically significant breast cancer in women with suspicious calcifications on mammography?

OBJECTIVE

To evaluate the diagnostic accuracy of positron emission mammography (PEM) for identifying malignant lesions in patients with suspicious microcalcifications detected on mammography.

METHODS

A prospective, single-centre study that evaluated 40 patients with suspicious calcifications at mammography and indication for percutaneous or surgical biopsy, with mean age of 56.4 years (range: 28-81 years). Patients who agreed to participate in the study underwent PEM with 18F-fluorodeoxyglucose before the final histological evaluation. PEM findings were compared with mammography and histological findings.

RESULTS

Most calcifications (n = 34; 85.0 %) were classified as BIRADS 4. On histology, there were 25 (62.5 %) benign and 15 (37.5 %) malignant lesions, including 11 (27.5 %) ductal carcinoma in situ (DCIS) and 4 (10 %) invasive carcinomas. On subjective analysis, PEM was positive in 15 cases (37.5 %) and most of these cases (n = 14; 93.3 %) were confirmed as malignant on histology. There was one false-positive result, which corresponded to a fibroadenoma, and one false negative, which corresponded to an intermediate-grade DCIS. PEM had a sensitivity of 93.3 %, specificity of 96.0 % and accuracy of 95 %.

CONCLUSION

PEM was able to identify all invasive carcinomas and high-grade DCIS (nuclear grade 3) in the presented sample, suggesting that this method may be useful for further evaluation of patients with suspected microcalcifications.

KEY POINTS

• Many patients with suspicious microcalcifications at mammography have benign results at biopsy. • PEM may help to identify invasive carcinomas and high-grade DCIS. • Management of patients with suspicious calcifications can be improved.

Evolution and Developments in Instrumentation for Positron Emission Mammography

Molecular imaging using high-resolution PET instrumentation is now playing a pivotal role in basic and clinical research. The development of optimized detection geometries combined with high-performance detector technologies and compact designs of PET tomographs have become the goal of active research groups in academic and corporate settings. Significant progress has been achieved in the design of commercial PET instrumentation in the last decade allowing a spatial resolution of about 4 to 6 mm to be reached for whole-body imaging, about 2.4 mm for PET cameras dedicated for brain imaging, and submillimeter resolution for female breast, prostate, and small-animal imaging. In particular, significant progress has been made in the design of dedicated positron emission mammography (PEM) units. The initial concept suggested in 1993 consisted of placing 2 planar detectors capable of detecting the 511-keV annihilation photons in a conventional mammography unit. Since that time, many different design paths have been pursued and it will be interesting to see which technologies become the most successful in the future. This paper discusses recent advances in PEM instrumentation and the advantages and challenges of dedicated standalone and dual-modality imaging systems. Future opportunities and the challenges facing the adoption of PEM imaging instrumentation and its role in clinical and research settings are also addressed.

Positron Emission Mammography Image Interpretation for Reduced Image Count Levels

We studied the effects of reduced (18)F-FDG injection activity on interpretation of positron emission mammography (PEM) images and compared image interpretation between 2 postinjection imaging times.

METHODS

We performed a receiver-operating-characteristic (ROC) study using PEM images reconstructed with different count levels expected from injected activities between 23 and 185 MBq. Thirty patients received 2 PEM scans at postinjection times of 60 and 120 min. Half of the patients were scanned with a standard protocol; the others received one-half of the standard activity. Images were reconstructed using 100%, 50%, and 25% of the total counts acquired. Eight radiologists used a 5-point confidence scale to score 232 PEM images for the presence of up to 3 malignant lesions. Paired images were analyzed with conditional logistic regression and ROC analysis to investigate changes in interpretation.

RESULTS

There was a trend for increasing lesion detection sensitivity with increased image counts: odds ratios were 2.2 (P = 0.01) and 1.9 (P = 0.04) per doubling of image counts for 60- and 120-min uptake images, respectively, without significant difference between time points (P = 0.7). The area under the ROC curve (AUC) was highest for the 100%-count, 60-min images (0.83 vs. 0.75 for 50%-counts, P = 0.02). The 120-min images had a similar trend but did not reach statistical significance (AUC = 0.79 vs. 0.73, P = 0.1). Our data did not yield significant trends between specificity and image counts. Lesion-to-background ratios increased between 60- and 120-min scans (P < 0.001).

CONCLUSION

Reducing the image counts relative to the standard protocol decreased diagnostic accuracy. The increase in lesion-to-background ratio between 60- and 120-min uptake times was not enough to improve detection sensitivity in this study, perhaps in part due to fewer counts in the later scan.

Positron emission mammography in the diagnosis of breast cancer. Is maximum PEM uptake value a valuable threshold for malignant breast cancer detection?

AIM

To evaluate the diagnostic value (sensitivity, specificity) of positron emission mammography (PEM) in a single site non-interventional study using the maximum PEM uptake value (PUVmax).

PATIENTS, METHODS

In a singlesite, non-interventional study, 108 patients (107 women, 1 man) with a total of 151 suspected lesions were scanned with a PEM Flex Solo II (Naviscan) at 90 min p.i. with 3.5 MBq 18F-FDG per kg of body weight. In this ROI(region of interest)-based analysis, maximum PEM uptake value (PUV) was determined in lesions, tumours (PUVmaxtumour), benign lesions (PUVmaxnormal breast) and also in healthy tissues on the contralateral side (PUVmaxcontralateral breast). These values were compared and contrasted. In addition, the ratios of PUVmaxtumour / PUVmaxcontralateral breast and PUVmaxnormal breast / PUVmaxcontralateral breast were compared. The image data were interpreted independently by two experienced nuclear medicine physicians and compared with histology in cases of suspected carcinoma.

RESULTS

Based on a criteria of PUV>1.9, 31 out of 151 lesions in the patient cohort were found to be malignant (21%). A mean PUVmaxtumour of 3.78 ± 2.47 was identified in malignant tumours, while a mean PUVmaxnormal breast of 1.17 ± 0.37 was reported in the glandular tissue of the healthy breast, with the difference being statistically significant (p < 0.001). Similarly, the mean ratio between tumour and healthy glandular tissue in breast cancer patients (3.15 ± 1.58) was found to be significantly higher than the ratio for benign lesions (1.17 ± 0.41, p < 0.001).

CONCLUSION

PEM is capable of differentiating breast tumours from benign lesions with 100% sensitivity along with a high specificity of 96%, when a threshold of PUVmax >1.9 is applied.

A preliminary report of breast cancer screening by positron emission mammography

OBJECTIVE

Fluorine-18 fluorodeoxyglucose (FDG)-positron emission tomography (PET) and PET/computed tomography (PET/CT) have had a considerable impact on the detection of various malignancies. PET and PET/CT are minimally invasive methods that can provide whole-body imaging at one time. Therefore, an FDG-PET cancer screening program has been widely used in Japan. However, the breast cancer detection rate of FDG-PET cancer screening is relatively low. Therefore, FDG-PET screening is not recommended for breast cancer screening. Positron emission mammography (PEM) is a high-resolution molecular breast imaging technology. PEM can detect small breast cancers that cannot be detected on PET or PET/CT images due to limited spatial resolution. We have performed opportunistic breast cancer screening using PEM since 2011. To the best of our knowledge, this is the first report regarding PEM breast cancer screening.

METHODS

This study enrolled 265 women. PEM images were analyzed by agreement of 2 experienced nuclear medicine physicians. The readers were given information from medical interview sheet. US findings were interpreted holistically. The number of participants, patient recall rate, further examination rate, and cancer detection rate by year were calculated.

RESULTS

The overall recall rate was 8.3%; the work-up examination rate was 77.3%, and cancer detection rate was 2.3%. The positive predictive value of PEM was 27.3%. Six cancers were found by PEM screening. Five were invasive cancers and one was ductal carcinoma in situ. Histological tumor sizes were reported in three cases: 0.7, 1.2, and 2 cm.

CONCLUSION

PEM screening appears to have potential for breast cancer screening.

Comparative analysis of imaging sensitivity of positron emission mammography and whole-body PET in relation to tumor size

OBJECTIVE

Positron emission mammography (PEM) consists of a dedicated PET scanner for breast imaging with a higher spatial resolution than whole-body PET (WBPET) scanners. This study compared the imaging sensitivity of PEM with WBPET in relation to tumor size.

METHODS

Fifty-four Japanese women younger than 50 years with histologically confirmed breast lesions were retrospectively enrolled. Positron emission mammography and WBPET were conducted on the same day. Positron emission mammography and WBPET images were blindly evaluated and compared with histopathology. Tumors were classified into 3 groups based on size as follows: group 1, 1 cm or smaller; group 2, 1 to 2 cm; and group 3, larger than 2 cm. The sensitivities of PEM and WBPET were compared in overall subjects and in each size group.

RESULTS

In visual analysis, the overall imaging sensitivity was 78.6% (33/42) for PEM and 47.6% (20/42) for WBPET. The overall sensitivity of PEM was significantly higher than that of WBPET (P < 0.001). The differences in sensitivities between PEM and WBPET were larger in smaller tumors: group 1 (66.7% vs 13.3%), group 2 (63.4% vs 36.4%), and group 3 (100.0% vs 87.5%). The sensitivity of PEM was significantly higher than that of WBPET in group 1 (P = 0.008); however, no significant differences were seen in group 2 (P = 0.500) or group 3 (P = 0.250). Overall, the imaging specificity of PEM and WEBPET was 90.6% (60/66) and 93.9% (62/66), respectively.

CONCLUSIONS

The imaging sensitivity of PEM was higher than that of WBPET in Japanese women younger than 50 years. Positron emission mammography showed significant sensitivity in tumors smaller than 1 cm, which has been a weak point for WBPET.

Current and Future Methods for Measuring Breast Density: A Brief Comparative Review

Breast density is one of the strongest predictors of breast cancer risk. Women with the densest breasts are 4 to 6 times more likely to develop cancer compared with those with the lowest densities. Breast density is generally assessed using mammographic imaging; however, this approach has limitations. Magnetic resonance imaging and ultrasound tomography are some alternative imaging modalities that can aid mammography in patient screening and the measurement of breast density. As breast density becomes more commonly discussed, knowledge of the advantages and limitations of breast density as a marker of risk will become more critical. This review article discusses the relationship between breast density and breast cancer risk, lists the benefits and drawbacks of using multiple different imaging modalities to measure density and briefly discusses how breast density will be applied to aid in breast cancer prevention and treatment.

Diagnostic workup and costs of a single supplemental molecular breast imaging screen of mammographically dense breasts

OBJECTIVE

The purpose of this study was to examine additional diagnostic workup and costs generated by addition of a single molecular breast imaging (MBI) examination to screening mammography for women with dense breasts.

SUBJECTS AND METHODS

Women with mammographically dense breasts presenting for screening mammography underwent adjunct MBI performed with 300 MBq (99m)Tc-sestamibi and a direct-conversion cadmium-zinc-telluride dual-head gamma camera. All subsequent imaging tests and biopsies were tracked for a minimum of 1 year. The positive predictive value of biopsies performed (PPV3), benign biopsy rate, cost per patient screened, and cost per cancer detected were determined.

RESULTS

A total of 1651 women enrolled in the study. Among the 1585 participants with complete reference standard, screening mammography alone prompted diagnostic workup of 175 (11.0%) patients and biopsy of 20 (1.3%) and yielded five malignancies (PPV3, 25%). Results of combined screening mammography plus MBI prompted diagnostic workup of 279 patients (17.6%) and biopsy of 67 (4.2%) and yielded 19 malignancies (PPV3, 28.4%). The benign biopsy rates were 0.9% (15 of 1585) for screening mammography alone and 3.0% (48 of 1585) for the combination (p < 0.001). The addition of MBI increased the cost per patient screened from $176 for mammography alone to $571 for the combination. However, cost per cancer detected was lower for the combination ($47,597) than for mammography alone ($55,851).

CONCLUSION

The addition of MBI to screening mammography of women with dense breasts increased the overall costs and benign biopsy rate but also increased the cancer detection rate, which resulted in a lower cost per cancer detected than with screening mammography alone.

Positron Emission Tomography in Breast Cancer

Gradually, FDG-PET/CT has been strengthening within the diagnostic algorithms of oncological diseases. In many of these, PET/CT has shown to be useful at different stages of the disease: diagnosis, staging or re-staging, treatment response assessment, and recurrence. Some of the advantages of this imaging modality versus CT, MRI, bone scan, mammography, or ultrasound, are based on its great diagnostic capacity since, according to the radiopharmaceutical used, it reflects metabolic changes that often occur before morphological changes and therefore allows us to stage at diagnosis. Moreover, another advantage of this technique is that it allows us to evaluate the whole body so it can be very useful for the detection of distant disease. With regard to breast cancer, FDG-PET/CT has proven to be important when recurrence is suspected or in the evaluation of treatment response. The technological advancement of PET equipment through the development of new detectors and equipment designed specifically for breast imaging, and the development of more specific radiopharmaceuticals for the study of the different biological processes of breast cancer, will allow progress not only in making the diagnosis of the disease at an early stage but also in enabling personalized therapy for patients with breast cancer.

Correlation between PET/CT results and histological and immunohistochemical findings in breast carcinomas

Objective

To correlate the results of ¹⁸F-fluoro-2-deoxy-D-glucose ⁽¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) performed with a specific protocol for assessment of breasts with histological/immunohistochemical findings in breast carcinoma patients.

Materials and Methods

Cross-sectional study with prospective data collection, where patients with biopsy-confirmed breast carcinomas were studied. The patients underwent PET/CT examination in prone position, with a specific protocol for assessment of breasts. PET/CT findings were compared with histological and immunohistochemical data.

Results

The authors identified 59 malignant breast lesions in 50 patients. The maximum diameter of the lesions ranged from 6 to 80 mm (mean: 32.2 mm). Invasive ductal carcinoma was the most common histological type (n = 47; 79.7%). At PET/CT, 53 (89.8%) of the lesions demonstrated anomalous concentrations of ¹⁸F-FDG, with maximum SUV ranging from 0.8 to 23.1 (mean: 5.5). A statistically significant association was observed between higher values of maximum SUV and histological type, histological grade, molecular subtype, tumor diameter, mitotic index and Ki-67 expression.

Conclusion

PET/CT performed with specific protocol for assessment of breasts has demonstrated good sensitivity and was associated with relevant histological/immunohistochemical factors related to aggressiveness and prognosis of breast carcinomas.

[Molecular breast imaging. An update]

CLINICAL/METHODICAL ISSUE

The aim of molecular imaging is to visualize and quantify biological, physiological and pathological processes at cellular and molecular levels. Molecular imaging using various techniques has recently become established in breast imaging.

STANDARD RADIOLOGICAL METHODS

Currently molecular imaging techniques comprise multiparametric magnetic resonance imaging (MRI) using dynamic contrast-enhanced MRI (DCE-MRI), diffusion-weighted imaging (DWI), proton MR spectroscopy ((1)H-MRSI), nuclear imaging by breast-specific gamma imaging (BSGI), positron emission tomography (PET) and positron emission mammography (PEM) and combinations of techniques (e.g. PET-CT and multiparametric PET-MRI).

METHODICAL INNOVATIONS

Recently, novel techniques for molecular imaging of breast tumors, such as sodium imaging ((23)Na-MRI), phosphorus spectroscopy ((31)P-MRSI) and hyperpolarized MRI as well as specific radiotracers have been developed and are currently under investigation.

PRACTICAL RECOMMENDATIONS

It can be expected that molecular imaging of breast tumors will enable a simultaneous assessment of the multiple metabolic and molecular processes involved in cancer development and thus an improved detection, characterization, staging and monitoring of response to treatment will become possible.