Diagnostic performance of breast-specific gamma imaging in the assessment of residual tumor after neoadjuvant chemotherapy in breast cancer patients

Current Concepts in Molecular Breast Imaging

Molecular breast imaging (MBI) is a functional imaging modality that utilizes technetium 99m sestamibi radiotracer uptake to evaluate the biology of breast tumors. Molecular breast imaging can be a useful tool for supplemental screening of women with dense breasts, for breast cancer diagnosis and staging, and for evaluation of treatment response in patients with breast cancer undergoing neoadjuvant systemic therapy. In addition, MBI is useful in problem-solving when mammography and US imaging are insufficient to arrive at a definite diagnosis and for patients who cannot undergo breast MRI. Based on the BI-RADS lexicon, a standardized lexicon has been developed to aid radiologists in MBI reporting. In this article, we review MBI equipment, procedures, and lexicon; clinical indications for MBI; and the radiation dose associated with MBI.

Molecular Breast Imaging and Positron Emission Mammography

There is growing interest in application of functional imaging modalities for adjunct breast imaging due to their unique ability to evaluate molecular/pathophysiologic changes, not visible by standard anatomic breast imaging. This has led to increased use of nuclear medicine dedicated breast-specific single photon and coincidence imaging systems for multiple indications, such as supplemental screening, staging of newly diagnosed breast cancer, evaluation of response to neoadjuvant treatment, diagnosis of local disease recurrence in the breast, and problem solving. Studies show that these systems maybe especially useful for specific subsets of patients, not well served by available anatomic breast imaging modalities.

ACR Appropriateness Criteria® Monitoring Response to Neoadjuvant Systemic Therapy for Breast Cancer: 2022 Update

Imaging plays a vital role in managing patients undergoing neoadjuvant chemotherapy, as treatment decisions rely heavily on accurate assessment of response to therapy. This document provides evidence-based guidelines for imaging breast cancer before, during, and after initiation of neoadjuvant chemotherapy. 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 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 where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Comparison of BSGI and MRI as Approaches to Evaluating Residual Tumor Status after Neoadjuvant Chemotherapy in Chinese Women with Breast Cancer

Background: The present retrospective study was designed to evaluate the relative diagnostic utility of breast-specific gamma imaging (BSGI) and breast magnetic resonance imaging (MRI) as means of evaluating female breast cancer patients in China. Methods: A total of 229 malignant breast cancer patients underwent ultrasound, mammography, BSGI, and MRI between January 2015 and December 2018 for initial tumor staging. Of these patients, 73 were subsequently treated via definitive breast surgery following neoadjuvant chemotherapy (NAC), of whom 17 exhibited a complete pathologic response (pCR) to NAC. Results: BSGI and MRI were associated with 76.8% (43/56) and 83.9% (47/56) sensitivity (BSGI vs. MRI, p = 0.341) values, respectively, as a means of detecting residual tumors following NAC, while both these approaches exhibited comparable specificity in this diagnostic context. The specificity of BSGI for detecting residual tumors following NAC was 70.6% (12/17), and that of MRI was 58.8% (10/17) (BSGI vs. MRI, p = 0.473). Conclusion: These results demonstrate that BSGI is a useful auxiliary approach to evaluating pCR to NAC treatment.

Molecular Breast Imaging: A Scientific Review

Molecular breast imaging (MBI) is a nuclear medicine technique that has evolved considerably over the past two decades. Technical advances have allowed reductions in administered doses to the point that they are now acceptable for screening. The most common radiotracer used in MBI, 99mTc-sestamibi, has a long history of safe use. Biopsy capability has become available in recent years, with early clinical experience demonstrating technically successful biopsies of MBI-detected lesions. MBI has been shown to be an effective supplemental screening tool in women with dense breasts and is also utilized for breast cancer staging, assessment of response to neoadjuvant chemotherapy, problem solving, and as an alternative to breast MRI in women who have a contraindication to MRI. The degree of background parenchymal uptake on MBI shows promise as a tool for breast cancer risk stratification. Radiologist interpretation is guided by a validated MBI lexicon that mirrors the BI-RADS lexicon. With short interpretation times, a fast learning curve for radiologists, and a substantially lower cost than breast MRI, MBI provides many benefits in the practices in which it is utilized. This review will discuss the current state of MBI technology, clinical applications of MBI, MBI interpretation, radiation dose associated with MBI, and the future of MBI.

99mTC-sestamibi breast imaging: Current status, new ideas and future perspectives

Here we proposed the most recent innovations in the use of Breast Specific Gamma Imaging with ⁹⁹mTc-sestamibi for the management of breast cancer patients. To this end, we reported the recent discoveries concerning: a) the implementation of both instrumental devices and software, b) the biological mechanisms involved in the ⁹⁹mTc-sestamibi uptake in breast cancer cells, c) the evaluation of Breast Specific Gamma Imaging with ⁹⁹mTc-sestamibi as predictive markers of metastatic diseases. In this last case, we also reported preliminary data about the capability of Breast Specific Gamma Imaging with ⁹⁹mTc-sestamibi to identify breast cancer lesions with high propensity to form bone metastatic lesions due to the presence of Breast Osteoblast-Like Cells.

Breast-Specific Gamma Imaging Versus MRI: Comparing the Diagnostic Performance in Assessing Treatment Response After Neoadjuvant Chemotherapy in Patients With Breast Cancer

OBJECTIVE

The purpose of this retrospective study was to evaluate the diagnostic performance of breast-specific gamma imaging (BSGI) and breast MRI in assessing for residual tumor after neoadjuvant chemotherapy (NAC) in patients with breast cancer.

MATERIALS AND METHODS

A total of 114 patients underwent BSGI and MRI for initial staging as well as after undergoing NAC. Of those, 112 underwent subsequent definitive breast surgery. Thirty of the 114 patients had a complete pathologic response to NAC.

RESULTS

BSGI and MRI had comparable sensitivities in detecting residual tumor after NAC (70% vs 83%). BSGI had a higher specificity than MRI in accurately determining complete response after NAC (90% vs 60%).

CONCLUSION

BSGI may be a useful adjunctive tool for predicting a complete pathologic response to NAC.

Dedicated Breast Gamma Camera Imaging and Breast PET: Current Status and Future Directions

Recent advances in nuclear medicine instrumentation have led to the emergence of improved molecular imaging techniques to image breast cancer: dedicated gamma cameras using γ-emitting ^99mTc-sestamibi and breast-specific PET cameras using ¹⁸F-fluorodeoxyglucose. This article focuses on the current role of such approaches in the clinical setting including diagnosis, assessing local extent of disease, monitoring response to therapy, and, for gamma camera imaging, possible supplemental screening in women with dense breasts. Barriers to clinical adoption and technologies and radiotracers under development are also discussed.

Comparison of Breast MR Imaging with Molecular Breast Imaging in Breast Cancer Screening, Diagnosis, Staging, and Treatment Response Evaluation

Breast MR imaging and molecular breast imaging (MBI) are functional imaging modalities that can be used to noninvasively evaluate the pathophysiology and biology of breast cancer. In the era of personalized medicine, these imaging techniques give clinicians insight into cancer pathobiology and allows them to individualize treatment regimens. Breast MR imaging has gained acceptance for breast cancer evaluation; work is ongoing on validation of MBI for breast cancer evaluation. This article discusses clinical applications of breast MR imaging and MBI, and compares the performance of these techniques in breast cancer screening, diagnosis, staging, and treatment response evaluation.

The role of molecular breast imaging in predicting complete tumor response to treatment and residual tumor extent following neoadjuvant therapy

The aim of the present study was to investigate the usefulness of molecular breast imaging (MBI) in predicting complete tumor response to treatment and residual tumor extent following neoadjuvant therapy. A consecutive series of 43 female patients with large or locally advanced primary breast cancer, scheduled for surgery following neoadjuvant therapy, was retrospectively reviewed. Prior to surgery, all patients underwent MBI using a high‑resolution semiconductor‑based device for image acquisition. MBI data were correlated with surgical histopathological findings. Spearman's correlation coefficient was calculated to assess differences in residual tumor size with MBI and histopathological examination. From the images obtained using MBI, 7 patients were negative for residual tumors with pathological complete response (specificity, 100%) and positive in 34/36 patients with residual disease (sensitivity, 94.4%), including 26/27 patients with unifocal and 8/9 patients with multicentric/multifocal tumors, 5 of which exhibited multiple microscopic foci scattered in a fibrotic area. Overall accuracy was 95.3% and the positive predictive value (PPV) and negative predictive value (NPV) were 100 and 77.8%, respectively. MBI was false‑negative in one patient with a 2.5‑cm invasive ductal carcinoma located close to the chest wall and in one patient with microscopic foci of epithelial carcinoma. In the patients with unifocal residual tumors, correlation of tumor size between MBI and histopathology was r=0.981 (P<0.0001); however, MBI overestimated the number of lesions in one of these cases. In the patients with multifocal/multicentric tumors, MBI adequately assessed residual tumor extent in 5/8 positive cases, overestimating the number of lesions in one case and underestimating tumor extent in 2 further cases with microscopic foci scattered in a fibrotic area. MBI proved to be a highly accurate diagnostic tool in predicting complete tumor response to neoadjuvant therapy and residual tumor extent, correlating with surgical histopathological findings in 86% of overall cases. A positive result was always associated with the presence of residual disease and MBI tumor size was strongly correlated with histopathological analysis mainly in unifocal residual tumors.

Slanetz PJ, Moy L, Baron P, diFlorio RM, Green ED, Heller SL, Holbrook AI, Lee SJ, Lewin AA, Lourenco AP, Niell B, Stuckey AR, Trikha S, Vincoff NS, Weinstein SP, Yepes MM, Newell MS. ACR Appropriateness Criteria® Monitoring Response to Neoadjuvant Systemic Therapy for Breast Cancer

Patients with locally advanced invasive breast cancers are often treated with neoadjuvant chemotherapy prior to definitive surgical intervention. The primary aims of this approach are to: 1) reduce tumor burden thereby permitting breast conservation rather than mastectomy; 2) promptly treat possible metastatic disease, whether or not it is detectable on preoperative staging; and 3) potentially tailor future chemotherapeutic decisions by monitoring in-vivo tumor response. Accurate radiological assessment permits optimal management and planning in this population. However, assessment of tumor size and response to treatment can vary depending on the modality used, the measurement technique (such as single longest diameter, 3-D measurements, or calculated tumor volume), and varied response of different tumor subtypes to neoadjuvant chemotherapy (such as concentric shrinkage or tumor fragmentation). As discussed in further detail, digital mammography, digital breast tomosynthesis, US and MRI represent the key modalities with potential to help guide patient management. 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.

Role of Magnetic Resonance Imaging in Detection of Pathologic Complete Remission in Breast Cancer Patients Treated With Neoadjuvant Chemotherapy: A Meta-analysis

Pathologic complete remission after neoadjuvant chemotherapy has a role in guiding the management of breast cancer. The present meta-analysis examined the accuracy of contrast-enhanced magnetic resonance imaging (CE-MRI) and diffusion-weighted magnetic resonance imaging (DW-MRI) in detecting the response to neoadjuvant chemotherapy and compared CE-MRI with ultrasonography, mammography, and positron emission tomography/computed tomography (PET/CT). Medical subject heading terms and related keywords were searched to generate a compilation of eligible studies. The pooled sensitivity, specificity, diagnostic odds ratio, area under summary receiver operating characteristic curve (AUC), and Youden index (Q* index) were used to estimate the diagnostic efficacy of CE-MRI, DW-MRI, ultrasonography, mammography, and PET/CT. A total of 54 studies of CE-MRI and 8 studies of DW-MRI were included. The overall AUC and the Q* index values for CE-MRI and DW-MRI were 0.88 and 0.94 and 0.80 and 0.85, respectively. According to the summary receiver operating characteristic curves, CE-MRI resulted in a higher AUC value and Q* index compared with ultrasonography and mammography but had values similar to those of DW-MRI and PET/CT. CE-MRI accurately assessed pathologic complete remission in specificity, and PET/CT and DW-MRI accurately assessed pathologic complete remission in sensitivity. The present meta-analysis indicates that CE-MRI has high specificity and DW-MRI has high sensitivity in predicting pathologic complete remission after neoadjuvant chemotherapy. CE-MRI is more accurate than ultrasonography or mammography. Additionally, PET/CT is valuable for predicting pathologic complete remission. CE-MRI, combined with PET/CT or DW-MRI, might allow for a more precise assessment of pathologic complete remission.

Assessment of Residual Disease With Molecular Breast Imaging in Patients Undergoing Neoadjuvant Therapy: Association With Molecular Subtypes

BACKGROUND

Assessment of residual disease after neoadjuvant therapy for breast cancer is an ongoing challenge of breast imaging. This study evaluates the accuracy of a novel dedicated system for molecular breast imaging (MBI) composed of the new generation of cadmium zinc telluride detectors in assessing residual disease after neoadjuvant therapy in patients with breast cancer.

PATIENTS AND METHODS

Clinical data, imaging, surgical, and pathological findings of 51 women with breast cancer undergoing neoadjuvant therapy were recorded. MBI findings were correlated with surgical pathology results. Accuracy of MBI in predicting complete pathological response and size of residual disease was assessed according to molecular subtypes.

RESULTS

The size of the largest focus of uptake on MBI correlated with the largest dimension measured on pathology (r = 0.55; P < .001). This correlation was stronger for triple negative and HER2/neu positive subtypes (r = 0.92 and 0.62, respectively). Sixteen patients (31%) had complete pathological response. The sensitivity and specificity of MBI for detecting residual disease were 83% (95% confidence interval [CI], 66-93) and 69% (95% CI, 42-88), respectively. For triple negative or HER2/neu positive disease the sensitivity and specificity were 88% (95% CI, 62-98) and 75% (95% CI, 43-93), respectively.

CONCLUSION

The accuracy of MBI in assessing residual disease after neoadjuvant treatment might be related to the molecular subtype. Accuracy is highest in the triple negative and HER2/neu positive subtypes.

Breast Imaging Utilizing Dedicated Gamma Camera and (99m)Tc-MIBI: Experience at the Tel Aviv Medical Center and Review of the Literature Breast Imaging

The scope of the current article is the clinical role of gamma cameras dedicated for breast imaging and (99m)Tc-MIBI tumor-seeking tracer, as both a screening modality among a healthy population and as a diagnostic modality in patients with breast cancer. Such cameras are now commercially available. The technology utilizing a camera composed of a NaI (Tl) detector is termed breast-specific gamma imaging. The technology of dual-headed camera composed of semiconductor cadmium zinc telluride detectors that directly converts gamma-ray energy into electronic signals is termed molecular breast imaging. Molecular breast imaging system has been installed at the Department of Nuclear medicine at the Tel Aviv Sourasky Medical Center, Tel Aviv in 2009. The article reviews the literature well as our own experience.

Role of imaging in neoadjuvant therapy for breast cancer

Neoadjuvant chemotherapy (NAC) involves administration of chemotherapeutic agents to patients with newly diagnosed breast cancer prior to definitive surgical treatment. Assessment of disease response to chemotherapeutic agents in vivo prior to any surgical intervention is necessary as medical oncologists are commonly tailoring or changing therapy during NAC based on response. It can also maximize the pathologic complete response (pCR) rate, resulting in more women undergoing breast conservation rather than mastectomy. Although some studies show a pCR to NAC in only 13-26 % of women, recent studies have shown higher pCR rates, especially for HER2-positive disease treated with targeted anti-HER2 therapy. Thus, accurate imaging tools for quantifying disease response are critical in the evaluation and management of patients undergoing NAC. There is currently no standard imaging method for monitoring response to therapy. Response to therapy tends to vary by tumor subtype and can be accurately assessed on imaging. We review the role of imaging before and after neoadjuvant therapy and discuss the advantages and limitations of currently available modalities, including mammography, ultrasonography, magnetic resonance imaging, and nuclear imaging.