99Tc(m)-tetrofosmin scintimammography for detecting breast cancer: a comparative study with 99Tc(m)-MIBI

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.

Study of the cytotoxicity of asiaticoside on rats and tumour cells

Background

Cancer chemoprevention is considered one of the most promising areas in current cancer research, and asiaticoside, which is derived from the plant Centella asiatica, has a relative lack of systemic toxicity. The purpose of this study was to investigate whether asiaticoside is effective against 7,12-dimethylbenz(a)anthracene (DMBA)-induced carcinogenicity in vitro (MCF-7 and other cells) and in vivo (DMBA-induced rat cancer).

Methods

An MTT assay was performed involving the treatment of MCF-7 cells for 48 h with H₂O₂ alone and H₂O₂ + different asiaticoside concentrations. Flow cytometry was performed, and the level of caspase 3, tumour necrosis factor-alpha (TNF-α) and interleukin-1 (IL-1) were quantified. Adult female Sprague–Dawley (SD) rats were divided into five groups designated I (control), II (DMBA-induced cancer), III (pre- and post-treatment with asiaticoside (200 μg/animal) in DMBA-induced cancer), IV (post-treatment with asiaticoside in DMBA-induced cancer), and V (treated with asiaticoside alone, drug control). Twelve weeks post-DMBA, rats developed mammary tumours. Rats either were sacrificed or imaged with MIBI. Histological examination of tumour tissues was performed. Tumour MIBI uptake ratios were determined. The data are expressed as the means ± standard deviation. Appropriate t-test and ANOVA statistical methods were used to compare data.

Results

The IC50 of asiaticoside for MCF-7 cells was determined to be 40 μM. Asiaticoside has potential for hydrogen peroxide cytotoxicity, and the caspase-3 activity increased with increasing asiaticoside dose in MCF-7 cells treated for 48 h. The expression of the cytokines TNF-α and IL-1β was significantly decreased and correlated with MIBI uptake ratios in vitro and in vivo after asiaticoside administration.

Conclusion

This study demonstrates that asiaticoside is effective in vitro and in vivo in inducing apoptosis and enhancing anti-tumour activity.

Functional Radionuclide Imaging, In-Vitro Radioiodine Uptake Estimation and RT-PCR in the Evaluation of Sodium Iodide Symporter (NIS) Expression and Functionality in Breast Cancer: A Pilot Study

Breast cancer is a common malignancy in females, which is considered as a systemic disease, whose treatment involves combined modality including systemic as well as local treatment. Recent studies have shown that breast cancer also expresses Sodium Iodide Symporter (NIS) gene, like in the thyroid, which is the factor responsible for the uptake of iodide by the thyroid, enabling radioiodine therapy of thyroid disorders. This study aimed to evaluate various radionuclide imaging characteristics, in vitro radioiodine uptake (RAIU) and evaluation of NIS expression by using Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) to explore sodium iodide symporter (NIS) expression and iodine uptake in breast cancer and to explor e whether radioiodine can be used for the diagnosis and treatment of breast cancer. Ways of differential regulation of NIS expression in breast cancer has also been explored. Female patients with palpable breast lump and histologically proven infiltrating duct carcinoma were taken up for the study, which included 50 females of mean age 49 years. (range: 23-73 years). The patients were categorized into different groups, depending on the type of the study performed. The uptake patterns in various imaging modalities were analyzed and compared with invitro and RT-PCR studies. 68 % of breast cancer cases showed (99m)Tc-pertechnetate uptake at the initial images. This finding could partly be due to tumor vascularity, which is usually higher compared to the normal tissues. The uptake in the delayed imaging could be related to that due to NIS in the breast. Use of perchlorate or stable iodine did not alter the pertechnetate uptake pattern in breast tumor. Good correlation between (99m)Tc-pertechnetate and (99m)Tc-tetrofosmin uptake in breast cancer was demonstrated. In vitro radioactive iodine uptake in the breast tumor was significantly higher than that in the normal breast tissue. Only 42 % of breast tumor samples studied using RT-PCR showed NIS expression. Correlation between (99m)Tc-pertechnetate uptake and NIS expression could not be well established. Further studies with higher dose of radioiodine and/or mechanisms of differentially blocking the thyroid are required to assess the feasibility of radioiodine therapy for breast cancer.

Quantification of lesion size, depth, and uptake using a dual-head molecular breast imaging system

A method to perform quantitative lesion analysis in molecular breast imaging (MBI) was developed using the opposing views from a novel dual-head dedicated gamma camera. Monte Carlo simulations and phantom models were used to simulate MBI images with known lesion parameters. A relationship between the full widths at 25%, 35%, and 50% of the maximum of intensity profiles through lesions and the true lesion diameter as a function of compressed breast thickness was developed in order to measure lesion diameter. Using knowledge of compressed breast thickness and the attenuation of gamma rays in soft tissue, a method was developed to measure the depth of the lesion to the collimator face. Using the measured lesion diameter and measurements of counts in the lesion and background breast region, relative radiotracer uptake or tumor to background ratio (T/B ratio) was calculated. Validation of the methods showed that the size, depth, and T/B ratio can be accurately measured for a range of small breast lesions with T/B ratios between 10:1 and 40:1 in breasts with compressed thicknesses between 4 and 10 cm. Future applications of this work include providing information about lesion location in patients for performing a biopsy of site and the development of a threshold for the T/B ratio that can distinguish benign from malignant disease.

Planar Tc99m--sestamibi scintimammography should be considered cautiously in the axillary evaluation of breast cancer protocols: results of an international multicenter trial

Background

Lymph node status is the most important prognostic indicator in breast cancer in recently diagnosed primary lesion. As a part of an interregional protocol using scintimammography with Tc99m compounds, the value of planar Tc99m sestamibi scanning for axillary lymph node evaluation is presented. Since there is a wide range of reported values, a standardized protocol of planar imaging was performed.

Methods

One hundred and forty-nine female patients were included prospectively from different regions. Their mean age was 55.1 ± 11.9 years. Histological report was obtained from 2.987 excised lymph nodes from 150 axillas. An early planar chest image was obtained at 10 min in all patients and a delayed one in 95 patients, all images performed with 740–925 MBq dose of Tc99m sestamibi. Blind lecture of all axillary regions was interpreted by 2 independent observers considering any well defined focal area of increased uptake as an involved axilla. Diagnostic values, 95% confidence intervals [CI] and also likelihood ratios (LR) were calculated.

Results

Node histology demonstrated tumor involvement in 546 out of 2987 lymph nodes. Sestamibi was positive in 30 axillas (25 true-positive) and negative in 120 (only 55 true-negative). The sensitivity corresponded to 27.8% [CI = 18.9–38.2] and specificity to 91.7% [81.6–97.2]. The positive and negative LR were 3.33 and 0.79, respectively. There was no difference between early and delayed images. Sensitivity was higher in patients with palpable lesions.

Conclusion

This work confirmed that non tomographic Tc99m sestamibi scintimammography had a very low detection rate for axillary lymph node involvement and it should not be applied for clinical assessment of breast cancer.

Clinical applications of 99mTc-sestamibi scintimammography

Mammography is the imaging modality of choice in detection of early, nonpalpable breast cancer. However, scintimammography may prove to be a very useful adjunct to a nondiagnostic or difficult mammography. Future prospective studies will have to be designed so that the specific clinical applications of scintimammography will be well defined. To be clinically relevant, each niche where scintimammography is potentially indicated should be clearly evaluated and incorporated into an algorithm of investigation of breast cancer, taking into consideration the relative advantages and limitations of scintimammography. Special care to obtain high-quality scintimammographic studies is mandatory. Because poor quality studies may be the major drawback, the nuclear medicine community should remind the lesson learned from radiologic mammography. Furthermore, it is also hoped that significant improvement in the scintigraphic equipment and data acquisition will be seen in a very near future to have more widespread clinical diagnostic applications of scintimammography.

Positive predictive value of 99mTc sestamibi scintimammography in patients with non-palpable, mammographically detected, suspicious, breast lesions

The purpose of this study was to analyse whether the use of Tc sestamibi scintimammography improves the positive predictive value of X-ray mammography. A series of 73 women (median age 51 years, range 35-79 years) with non-palpable, mammographically suspicious, breast lesions was reviewed. There were 41 (56.2%) pre-menopausal, and 32 (43.8%) post-menopausal women. All patients underwent sestamibi scintimammography prior to open breast biopsy. Definitive histology showed breast cancer (pT1a=1 (1.9%), pT1b=47 (90.4%), pT1c=4 (7.7%)) in 52 (71.2%) patients, and benign breast lesions in 21 (28.8%). Patients with cancer were significantly older (P <0.01), while the greatest dimension (size) of the excised lesion did not differ (8.47+/-1.51 vs 8.30+/-1.53 mm; P =0.66) between the two groups. Overall, the positive predictive values of mammography and sestamibi scintimammography were 71.2% and 95.7%, respectively (P =0.004). Patients with false positive mammography were significantly younger than those in whom cancer was diagnosed correctly (45.35+/-7.56 vs 53.96+/-10.60 years; P =0.001), while age did not affect the sensitivity of sestamibi scintimammography, which reached 100% in patients with breast lesions > or =8 mm in size. In this subgroup the positive predictive value of mammography, sestamibi scintimammography, and mammography+sestamibi scintimammography together were 63.4%, 95.1% (P =0.001), and 97.6%, respectively, and the majority of the patients with benign lesions (13 of 15 (86.7%)) could have avoided biopsy. It is concluded that the use of Tc sestamibi scintimammography in conjunction with mammography may potentially reduce unnecessary surgical procedures, and should be performed in all patients with mammographically suspicious breast lesions of 8 mm or greater in size.