Sensitivity, Specificity and the Diagnostic Accuracy of PET/CT for Axillary Staging in Patients With Stage I-III Cancer: A Systematic Review of The Literature

Detectability of Al18F-NOTA-HER2-BCH PET for Nodal Metastases in Patients With HER2-Positive Breast Cancer

PURPOSE

The aim of this study was to compare Al18F-NOTA-HER2-BCH and 18F-FDG for detecting nodal metastases in patients with HER2-positive breast cancer on PET/CT.

PATIENTS AND METHODS

In this retrospective study, 62 participants with HER2-positive breast cancer underwent both Al18F-NOTA-HER2-BCH and 18F-FDG PET/CT. Participants were pathologically confirmed as HER2-positive (IHC 3+ or IHC 2+ with gene amplification on FISH). Three independent readers visually assessed uptake of tracers on imaging. Furthermore, the diagnostic accuracy of nodal metastases was assessed using c-statistics. The lesion uptakes were quantified by SUVmax and target-to-background ratio (TBR) and compared using the general linear mixed model.

RESULTS

The findings showed nodal metastases in 33 (53%) participants, including 45% only with regional nodal metastasis and 55% with nonregional nodal metastasis. On per-patient level, the sensitivity and specificity of Al18F-NOTA-HER2-BCH and 18F-FDG based on the majority reads were 0.97, 0.97, and 0.85, 0.77, respectively. Five participants were visualized only on Al18F-NOTA-HER2-BCH. Seven participants with high uptake only on 18F-FDG PET/CT were confirmed to be inflammatory uptake by pathological results and later imaging follow-up. On per-lesion level, Al18F-NOTA-HER2-BCH PET/CT detected more axillary (98.8% vs 70.2%), extra-axillary (100% vs 61.7%), and nonregional (99.1% vs 67.0%) lymph nodal metastases than 18F-FDG PET/CT. Additionally, Al18F-NOTA-HER2-BCH PET/CT detected more nodal metastases small than 10 mm than 18F-FDG PET/CT (198 vs 125, 99.5% vs 62.8%). The median SUVmax and TBR of regional or nonregional nodal metastases at Al18F-NOTA-HER2-BCH were all higher than those on 18F-FDG (range of median SUVmax, 8.0-11.4 vs 2.3-5.6; P range, <0.001-0.007; range of median TBR, 7.3-16.3 vs 2.9-5.3; P range, <0.001). No adverse reactions related to imaging agents were observed in all participants.

CONCLUSIONS

Al18F-NOTA-HER2-BCH PET/CT detected more regional and nonregional lymph nodal metastases in patients with HER2-positive breast cancer than on 18F-FDG PET/CT, especially for lesions small than 10 mm.

Can we skip invasive biopsy of sentinel lymph nodes? A preliminary investigation to predict sentinel lymph node status using PET/CT-based radiomics

BACKGROUND

Sentinel lymph node (SLN) biopsy (SLNB) is considered the gold standard for detecting SLN metastases in patients with invasive ductal breast cancer (IDC). However, SLNB is invasive and associated with several complications. Thus, this study aimed to evaluate the diagnostic performance of a non-invasive radiomics analysis utilizing 2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography/computed tomography (18F-FDG-PET/CT) for assessing SLN metastasis in IDC patients.

METHODS

This retrospective study included 132 patients with biopsy-confirmed IDC, who underwent 18F-FDG PET/CT scans prior to mastectomy or breast-conserving surgery with SLNB. Tumor resection or SLNB was conducted within one-week post-scan. Clinical data and metabolic parameters were analyzed to identify independent SLN metastasis predictors. Radiomic features were extracted from each PET volume of interest (VOI) and CT-VOI. Feature selection involved univariate and multivariate logistic regression analysis, and the least absolute shrinkage and selection operator (LASSO) method. Three models were developed to predict SLN status using the random forest (RF), decision tree (DT), and k-Nearest Neighbors (KNN) classifiers. Model performance was assessed using the area under the receiver operating characteristic curve (AUC).

RESULTS

The study included 91 cases (32 SLN-positive and 59 SLN-negative patients) in the training cohort and 41 cases (29 SLN-positive and 12 SLN-negative patients) in the validation cohort. Multivariate logistic regression analysis identified Ki 67 and TLG as independent predictors of SLN status. Five PET-derived features, three CT-derived features, and two clinical variables were selected for model development. The AUC values of the RF, KNN, and DT models for the training cohort were 0.887, 0.849, and 0.824, respectively, and for the validation cohort were 0.856, 0.830, and 0.819, respectively. The RF model demonstrated the highest accuracy for the preoperative prediction of SLN metastasis in IDC patients.

CONCLUSION

The PET-CT radiomics approach may offer robust and non-invasive predictors for SLN status in IDC patients, potentially aiding in the planning of personalized treatment strategies for IDC patients.

Peritumoral edema enhances MRI-based deep learning radiomic model for axillary lymph node metastasis burden prediction in breast cancer

To investigate whether peritumoral edema (PE) could enhance deep learning radiomic (DLR) model in predicting axillary lymph node metastasis (ALNM) burden in breast cancer. Invasive breast cancer patients with preoperative MRI were retrospectively enrolled and categorized into low (< 2 lymph nodes involved (LNs+)) and high (≥ 2 LNs+) burden groups based on surgical pathology. PE was evaluated on T2WI, and intra- and peri-tumoral radiomic features were extracted from MRI-visible tumors in DCE-MRI. Deep learning models were developed for LN burden prediction in the training cohort and validated in an independent cohort. The incremental value of PE was evaluated through receiver operating characteristic (ROC) analysis, confirming the improvement in the area under the curve (AUC) using the Delong test. This was complemented by net reclassification improvement (NRI) and integrated discrimination improvement (IDI) metrics. The deep learning combined model, incorporating PE with selected radiomic features, demonstrated significantly higher AUC values compared to the MRI model and the DLR model in the training cohort (n = 177) (AUC: 0.953 vs. 0.849 and 0.867, p < 0.05) and the validation cohort (n = 111) (AUC: 0.963 vs. 0.883 and 0.882, p < 0.05). The complementary analysis demonstrated that PE significantly enhances the prediction performance of the DLR model (Categorical NRI: 0.551, p < 0.001; IDI = 0.343, p < 0.001). These findings were confirmed in the validation cohort (Categorical NRI: 0.539, p < 0.001; IDI = 0.387, p < 0.001). PE improved preoperative ALNM burden prediction of DLR model, facilitating personalized axillary management in breast cancer patients.

PET Molecular Imaging in Breast Cancer: Current Applications and Future Perspectives

Positron emission tomography (PET) plays a crucial role in breast cancer management. This review addresses the role of PET imaging in breast cancer care. We focus primarily on the utility of 18F-fluorodeoxyglucose (FDG) PET in staging, recurrence detection, and treatment response evaluation. Furthermore, we delve into the growing interest in precision therapy and the development of novel radiopharmaceuticals targeting tumor biology. This includes discussing the potential of PET/MRI and artificial intelligence in breast cancer imaging, offering insights into improved diagnostic accuracy and personalized treatment approaches.

Construction of a comprehensive predictive model for axillary lymph node metastasis in breast cancer: a retrospective study

PURPOSE

The accurate assessment of axillary lymph node metastasis (LNM) in early-stage breast cancer (BC) is of great importance. This study aimed to construct an integrated model based on clinicopathology, ultrasound, PET/CT, and PET radiomics for predicting axillary LNM in early stage of BC.

MATERIALS AND METHODS

124 BC patients who underwent 18 F-fluorodeoxyglucose (18 F-FDG) PET/CT and whose diagnosis were confirmed by surgical pathology were retrospectively analyzed and included in this study. Ultrasound, PET and clinicopathological features of all patients were analyzed, and PET radiomics features were extracted to establish an ultrasound model (clinicopathology and ultrasound; model 1), a PET model (clinicopathology, ultrasound, and PET; model 2), and a comprehensive model (clinicopathology, ultrasound, PET, and radiomics; model 3), and the diagnostic efficacy of each model was evaluated and compared.

RESULTS

The T stage, US_BIRADS, US_LNM, and PET_LNM in the positive axillary LNM group was significantly higher than that of in the negative LNM group (P = 0.013, P = 0.049, P < 0.001, P < 0.001, respectively). Radiomics score for predicting LNM (RS_LNM) for the negative LNM and positive LNM were statistically significant difference (-1.090 ± 0.448 vs. -0.693 ± 0.344, t = -4.720, P < 0.001), and the AUC was 0.767 (95% CI: 0.674-0.861). The ROC curves showed that model 3 outperformed model 1 for the sensitivity (model 3 vs. model 1, 82.86% vs. 48.57%), and outperformed model 2 for the specificity (model 3 vs. model 2, 82.02% vs. 68.54%) in the prediction of LNM. The AUC of mode 1, model 2 and model 3 was 0.687, 0.826 and 0.874, and the Delong test showed the AUC of model 3 was significantly higher than that of model 1 and model 2 (P < 0.05). Decision curve analysis showed that model 3 resulted in a higher degree of net benefit for all the patients than model 1 and model 2.

CONCLUSION

The use of a comprehensive model based on clinicopathology, ultrasound, PET/CT, and PET radiomics can effectively improve the diagnostic efficacy of axillary LNM in BC.

TRIAL REGISTRATION

This study was registered at ClinicalTrials Gov (number NCT05826197) on 7th, May 2023.

Contralateral lymph node metastasis in recurrent ipsilateral breast cancer with Lynch syndrome: a locoregional event

INTRODUCTION

Contralateral axillary lymph node metastasis (CALNM) in breast cancer (BC) is considered a distant metastasis, marking stage 4cancer. Therefore, it is generally treated as an incurable disease. However, in clinical practice, staging and treatment remain controversial due to a paucity of data, and the St. Gallen 2021 consensus panel recommended a curative approach in patients with oligometastatic disease. Aberrant lymph node (LN) drainage following previous surgery or radiotherapy is common. Therefore, CALNM may be considered a regional event rather than systemic disease, and a re-sentinel procedure aided by lymphoscintigraphy permits adequate regional staging.

CASE REPORT

Here, we report a 37-year-old patient with Lynch syndrome who presented with CALNM in an ipsilateral relapse of a moderately differentiated invasive ductal BC (ER 90%, PR 30%, HER2 negative, Ki-67 25%, microsatellite stable), 3 years after the initial diagnosis. Lymphoscintigraphy detected a positive sentinel LN in the contralateral axilla despite no sign of LN involvement or distant metastases on FDG PET/CT or MRI. The patient underwent bilateral mastectomy with sentinel node dissection, surgical reconstruction with histological confirmation of the CALNM, left axillary dissection, adjuvant chemotherapy, and anti-hormone therapy. In addition to her regular BC follow-up visits, the patient will undergo annual colonoscopy, gastroscopy, abdominal, and vaginal ultrasound screening. In January 2023, the patient was free of progression for 23 months after initiation of treatment for recurrent BC and CALNM.

CONCLUSION

This case highlights the value of delayed lymphoscintigraphy and the contribution of sentinel procedure for local control in the setting of recurrent BC. Aberrant lymph node drainage following previous surgery may be the underlying cause of CALNM. We propose that CALNM without evidence of systemic metastasis should be considered a regional event in recurrent BC, and thus, a curative approach can be pursued. The next AJCC BC staging should clarify the role of CALNM in recurrent BC to allow for the development of specific treatment guidelines.

The Role of PET/CT in Breast Cancer

Female breast cancer has surpassed lung cancer as the most commonly diagnosed cancer worldwide, with an estimated 2.3 million new cases (11.7%), followed by lung cancer (11.4%) The current literature and the National Comprehensive Cancer Network (NCCN) guidelines state that ¹⁸F-FDG PET/CT is not routine for early diagnosis of breast cancer, and rather PET/CT scanning should be performed for patients with stage III disease or when conventional staging studies yield non-diagnostic or suspicious results because this modality has been shown to upstage patients compared to conventional imaging and thus has an impact on disease management and prognosis. Furthermore, with the growing interest in precision therapy in breast cancer, numerous novel radiopharmaceuticals have been developed that target tumor biology and have the potential to non-invasively guide the most appropriate targeted therapy. This review discusses the role of ¹⁸F-FDG PET and other PET tracers beyond FDG in breast cancer imaging.

State of the Art in 2022 PET/CT in Breast Cancer: A Review

Molecular imaging with positron emission tomography is a powerful and well-established tool in breast cancer management. In this review, we aim to address the current place of the main PET radiopharmaceuticals in breast cancer care and offer perspectives on potential future radiopharmaceutical and technological advancements. A special focus is given to the following: the role of 18F-fluorodeoxyglucose positron emission tomography in the clinical management of breast cancer patients, especially during staging; detection of recurrence and evaluation of treatment response; the role of 16α-18Ffluoro-17β-oestradiol positron emission tomography in oestrogen receptors positive breast cancer; the promising radiopharmaceuticals, such as 89Zr-trastuzumab and 68Ga- or 18F-labeled fibroblast activation protein inhibitor; and the application of artificial intelligence.

Modern Imaging Techniques in the Study and Disease Diagnosis of the Mammary Glands of Animals

The study of the structure and function of the animals' mammary glands is of key importance, as it reveals pathological processes at their onset, thus contributing to their immediate treatment. The most frequently studied mammary diseases are mastitis in cows and ewes and mammary tumours in dogs and cats. Various imaging techniques such as computed tomography, positron emission tomography, magnetic resonance imaging, and ultrasonographic techniques (Doppler, contrast-enchanced, three-dimensional and elastography) are available and can be applied in research or clinical practice in order to evaluate possible abnormalities in mammary glands, as well as to assist in the differential diagnosis. In this review, the above imaging technologies are described, and the perspectives of each method are highlighted. It is inferred that ultrasonographic modalities are the most frequently used imaging techniques for the diagnosis of clinical or subclinical mastitis and treatment guidance on a farm. In companion animals, a combination of imaging techniques should be applied for a more accurate diagnosis of mammary tumours. In any case, the confirmation of the diagnosis is provided by laboratory techniques.

Prone versus Supine FDG PET/CT in the Staging of Breast Cancer

Supine [18F]Fluorodeoxyglucose (FDG) positron emission technology/computed tomography (PET/CT) is a commonly used modality for the initial staging of breast cancer, and several previous studies have shown superior sensitivity and specificity of prone FDG PET/CT in comparison to its supine counterpart. This retrospective study included 25 females with breast cancer referred for staging. They underwent supine FDG PET/CT followed by prone FDG PET/CT. The outcomes were: number of primary breast lesions, anatomical site of FDG-avid lymph nodes (LNs), and number and type of bone lesions, with SUVmax of all corresponding parameters. Performance was superior in prone acquisition compared to supine acquisition, with the respective results: 29 vs. 22 breast tumor lesions detected, 62 vs. 27 FDG-avid axillary LNs detected, sensitivity of 68% vs. 57%, specificity of 64% vs. 53%. The detection rate of axillary LNs in the prone position was significantly higher (p = 0.001). SUVmax for breast tumor lesions (p = 0.000) and number of detected axillary LNs (p = 0.002) were significantly higher in prone acquisition. Five patients were upstaged after experts read the prone acquisition. Prone FDG PET/CT acquisition is a promising technique in detecting primary breast lesions and metastatic LNs possibly missed in supine acquisition, which may lead to change in patient staging and management.

Escalating de-escalation in breast cancer treatment

Efforts have continually been made to de-escalate treatment for breast cancer, with the goal of balancing oncologic outcomes with complications and patient quality of life. In the early 2000s, two landmark studies firmly established that conservative treatment approaches for breast cancer can be safe and effective. More recently, neoadjuvant chemotherapy has gained momentum as a potential standard of care for breast cancer. An important question has thus arisen: Can neoadjuvant approaches themselves be de-escalated to further minimize adverse treatment effects while maintaining oncological outcomes? In this editorial, we look at the available evidence and assess current trends in treatment de-escalation for women with breast cancer.

PET-CT in Clinical Adult Oncology: II. Primary Thoracic and Breast Malignancies

Simple Summary

Positron emission tomography (PET), typically combined with computed tomography (CT), has become a critical advanced imaging technique in oncology. With PET-CT, a radioactive molecule (radiotracer) is injected in the bloodstream and localizes to sites of tumor because of specific cellular features of the tumor that accumulate the targeting radiotracer. The CT scan, performed at the same time, provides information to facilitate assessment of the amount of radioactivity from deep or dense structures, and to provide detailed anatomic information. PET-CT has a variety of applications in oncology, including staging, therapeutic response assessment, restaging, and surveillance. This series of six review articles provides an overview of the value, applications, and imaging and interpretive strategies of PET-CT in the more common adult malignancies. The second article in this series addresses the use of PET-CT in breast cancer and other primary thoracic malignancies.

Abstract

Positron emission tomography combined with x-ray computed tomography (PET-CT) is an advanced imaging modality with oncologic applications that include staging, therapy assessment, restaging, and surveillance. This six-part series of review articles provides practical information to providers and imaging professionals regarding the best use of PET-CT for the more common adult malignancies. The second article of this series addresses primary thoracic malignancy and breast cancer. For primary thoracic malignancy, the focus will be on lung cancer, malignant pleural mesothelioma, thymoma, and thymic carcinoma, with an emphasis on the use of FDG PET-CT. For breast cancer, the various histologic subtypes will be addressed, and will include ¹⁸F fluorodeoxyglucose (FDG), recently Food and Drug Administration (FDA)-approved ¹⁸F-fluoroestradiol (FES), and ¹⁸F sodium fluoride (NaF). The pitfalls and nuances of PET-CT in breast and primary thoracic malignancies and the imaging features that distinguish between subcategories of these tumors are addressed. This review will serve as a resource for the appropriate roles and limitations of PET-CT in the clinical management of patients with breast and primary thoracic malignancies for healthcare professionals caring for adult patients with these cancers. It also serves as a practical guide for imaging providers, including radiologists, nuclear medicine physicians, and their trainees.

Sentinel lymph node detection by combining nonradioactive techniques with contrast agents: State of the art and prospects

The status of sentinel lymph nodes (SLNs) has a substantial prognostic value because these nodes are the first place where cancer cells accumulate along their spreading route. Routine SLN biopsy ("gold standard") involves peritumoral injections of radiopharmaceuticals, such as technetium-99m, which has obvious disadvantages. This review examines the methods used as "gold standard" analogs to diagnose SLNs. Nonradioactive preoperative and intraoperative methods of SLN detection are analyzed. Promising photonic tools for SLNs detection are reviewed, including NIR-I/NIR-II fluorescence imaging, photoswitching dyes for SLN detection, in vivo photoacoustic detection, imaging and biopsy of SLNs. Also are discussed methods of SLN detection by magnetic resonance imaging, ultrasonic imaging systems including as combined with photoacoustic imaging, and methods based on the magnetometer-aided detection of superparamagnetic nanoparticles. The advantages and disadvantages of nonradioactive SLN-detection methods are shown. The review concludes with prospects for the use of conservative diagnostic methods in combination with photonic tools.

Clinical Significance of Peritumoral Adipose Tissue PET/CT Imaging Features for Predicting Axillary Lymph Node Metastasis in Patients with Breast Cancer

We investigated whether textural parameters of peritumoral breast adipose tissue (AT) based on F-18 fluorodeoxyglucose (FDG) PET/CT could predict axillary lymph node metastasis in patients with breast cancer. A total of 326 breast cancer patients with preoperative FDG PET/CT were retrospectively enrolled. PET/CT images were visually assessed and the maximum FDG uptake of axillary lymph nodes (LN SUVmax) was measured. From peritumoral breast AT, 38 textural features of PET imaging were extracted. The diagnostic ability of PET based on visual analysis, LN SUVmax, and textural features of peritumoral breast AT for predicting axillary lymph node metastasis were assessed using the area under the receiver operating characteristic curve (AUC) values. Among the 38 peritumoral breast AT textural features, grey-level co-occurrence matrix (GLCM) entropy showed the highest AUC value (0.830) for predicting axillary lymph node metastasis. The value of GLCM entropy was higher than that of visual analysis (0.739; p < 0.05) and the AUC value was comparable to that of LN SUVmax (0.793; p > 0.05). In the subgroup analysis of patients with negative findings on visual analysis, GLCM entropy still showed a high diagnostic ability (AUC: 0.759) in predicting lymph node metastasis. The findings suggest a potential diagnostic role of PET/CT imaging features of peritumoral breast AT in predicting axillary lymph node metastasis in patients with breast cancer.

PET/CT Variants and Pitfalls in Breast Cancers

There are a number of normal variants and pitfalls which are important to consider when evaluating F-18 Fluorodeoxyglucose (FDG) with Positron Emission Tomography (PET) in breast cancer patients. Although FDG-PET is not indicated for the initial diagnosis of breast cancer, focally increased glucose metabolism within breast tissue represents a high likelihood for a neoplastic process and requires further evaluation. Focally increased glucose metabolism is not unique to breast cancer. Other malignancies such as lymphoma, metastases from solid tumors as well as inflammatory changes also may demonstrate increased glucose metabolism either within the breast or at other sites throughout the body. Importantly, benign breast disease may also exhibit increased glucose metabolism, limiting the specificity of FDG-PET. Breast cancer has a wide range of metabolic activity attributed to tumor heterogeneity and breast cancer subtype. Intracellular signaling pathways regulating tumor glucose utilization contribute to these pitfalls of PET/CT in breast cancer. The evaluation of axillary lymph nodes by FDG-PET is less accurate than sentinel lymph node procedure, however is very accurate in identifying level II and III axillary lymph node metastases or retropectoral metastases. It is important to note that non-malignant inflammation in lymph nodes are often detected by modern PET/CT technology. Therefore, particular consideration should be given to recent vaccinations, particularly to COVID-19, which can commonly result in increased metabolic activity of axillary nodes. Whole body FDG-PET for staging of breast cancer requires specific attention to physiologic variants of FDG distribution and a careful comparison with co-registered anatomical imaging. The most important pitfalls are related to inflammatory changes including sarcoidosis, sarcoid like reactions, and other granulomatous diseases as well as secondary neoplastic processes.

68Ga-FAPI-04 PET/CT, a new step in breast cancer imaging: a comparative pilot study with the 18F-FDG PET/CT

AIM

We aimed to compare the roles of 68Ga-FAPI-04 PET/CT and 18F-FDG PET/CT in the evaluation of primary tumor and metastases in primary and recurrent breast cancer.

MATERIALS AND METHOD

Twenty female patients with histopathologically confirmed primary and recurrent breast cancer were included in the prospective study. All patients underwent FDG and FAPI PET/CT imaging in the same week. The number of primary and metastatic lesions, SUVmax values, and tumor-to-background ratios (TBR) were recorded from both scans. Data obtained were statistically compared.

RESULTS

FAPI PET/CT was superior to FDG in detecting breast lesions, as well as hepatic, bone, lymph node, and cerebral metastases in terms of patient- and lesion-based assessments. The sensitivity and specificity of FAPI in detecting primary breast lesions were 100% and 95.6%, respectively, while the sensitivity and specificity of FDG were 78.2% and 100%, respectively. The SUVmax values of primary breast tumors, lymph nodes, lung metastases, and bone metastases were significantly higher on FAPI imaging than FDG imaging (p < 0.05). However, SUVmax values of hepatic metastases did not exhibit a statistically significant difference between two imaging techniques (p > 0.05). Also, FAPI imaging yielded significantly higher TBR in breast lesions as well as hepatic, bone, brain and lung metastases compared to FDG (p < 0.05).

CONCLUSION

68 Ga-FAPI-04 PET/CT is superior to 18F-FDG PET/CT in detecting the primary tumor in patients with breast cancer with its high sensitivity, high SUVmax, and high TBR. 68 Ga-FAPI-04 PET/CT is also superior to 18F-FDG PET/CT in detecting lymph node, hepatic, bone, and cerebral metastases because it has lower background activity and higher uptake in subcentimetric lesions.