A preliminary study to propose a diagnostic algorithm for PET/CT-detected incidental breast lesions: application of BI-RADS lexicon for US in combination with SUVmax

Diagnostic Characteristics and Clinical Relevance of Incidental Hypermetabolic Breast Lesions Detected on 18F-FDG PET-CT: A Retrospective Evaluation

RATIONALE AND OBJECTIVES

The study aimed to evaluate demographic and radiological characteristics of breast incidentalomas found on 18-fluorodeoxyglucose Positron Emission Tomography-Computed Tomography (18F-FDG PET-CT) performed for extramammary indications.

MATERIALS AND METHODS

A total of 12633 18F-FDG PET-CT scans performed between January 1, 2018 and January 1, 2024, were retrospectively reviewed. Breast incidentalomas that had undergone breast imaging, tissue diagnosis, or at least 2-year radiological follow-up were included. Demographic data and lesion size were recorded. Maximum and average standardized uptake values (SUVmax-SUVavg) and SUV corrected for lean body mass (SUL) were calculated using region of interest (ROI).

RESULTS

The inclusion criteria were met in 101 lesions (81 benign and 20 malignant). The most common benign lesion was fibroadenoma (n = 21), followed by stable lesions during follow-up (n = 18) and benign breast parenchyma (n = 11). The most common malignant lesion was invasive ductal carcinoma (n = 11). The diagnostic characteristics of SUVmax≥ 3, SULmax≥ 2, SUVavg≥ 0.735, SULavg≥ 0.48, and BI-RADS≥ 4 were 75%, 70%, 75%, 70% and 100% for sensitivity, 69%, 69%, 62%, 62% and 67% for specificity, and 69.3%, 68.3%, 62.4%, 61.4% and 73.3% for accuracy, respectively. The highest negative predictive values (NPV) were obtained with BI-RADS and SUVmax (100% and 92%, respectively). No significant difference in malignancy rate was observed for the lesion size and age of the patients (p > 0.05).

CONCLUSION

There is a risk of detecting malignancy in incidental lesions showing 18F-FDG uptake. Radiological workup must be done, but SUVmax, with a high NPV value, can be used in conjunction with BI-RADS assessment for appropriate patient selection and effective management of resources.

The lingering manifestations of COVID-19 during and after convalescence: update on long-term pulmonary consequences of coronavirus disease 2019 (COVID-19)

The long-term sequelae of coronavirus disease 2019 (COVID-19) are still unknown. Lessons from past viral epidemics reveal that, after recovery, patients with viral pulmonary infections can suffer from irreversible pulmonary dysfunction and demonstrate residual imaging or functional abnormalities. Residual ground glass opacities, consolidations, reticular and linear opacities, residual crazy paving pattern, melted sugar sign, and parenchymal fibrotic bands are several features found in the late or remission stages of COVID-19. These radiologic findings have been observed weeks after symptom onset, even after hospital discharge, and they may or may not correlate with clinical manifestations. High-resolution CT may be indicated to establish new baselines and track changes in residual impairments. In our previous review, we observed significant pulmonary sequelae in some COVID-19 survivors at follow-up. In this update, we review the current literature on the clinical and radiologic manifestations of post-recovery COVID-19 toward the end of hospital admission and after discharge.

Physiologic and hypermetabolic breast 18-F FDG uptake on PET/CT during lactation

OBJECTIVE

To investigate the patterns of breast cancer-related and lactation-related ¹⁸F-FDG uptake in breasts of lactating patients with pregnancy-associated breast cancer (PABC) and without breast cancer.

METHODS

¹⁸F-FDG-PET/CT datasets of 16 lactating patients with PABC and 16 non-breast cancer lactating patients (controls) were retrospectively evaluated. Uptake was assessed in the tumor and non-affected lactating tissue of the PABC group, and in healthy lactating breasts of the control group, using maximum and mean standardized uptake values (SUVmax and SUVmean, respectively), and breast-SUVmax/liver-SUVmean ratio. Statistical tests were used to evaluate differences and correlations between the groups.

RESULTS

Physiological uptake in non-breast cancer lactating patients' breasts was characteristically high regardless of active malignancy status other than breast cancer (SUVmax = 5.0 ± 1.7, n = 32 breasts). Uptake correlated highly between the two breasts (r = 0.61, p = 0.01), but was not correlated with age or lactation duration (p = 0.24 and p = 0.61, respectively). Among PABC patients, the tumors demonstrated high ¹⁸F-FDG uptake (SUVmax = 7.8 ± 7.2, n = 16), which was 326-643% higher than the mostly low physiological FDG uptake observed in the non-affected lactating parenchyma of these patients (SUVmax = 2.1 ± 1.1). Overall, ¹⁸F-FDG uptake in lactating breasts of PABC patients was significantly decreased by 59% (p < 0.0001) compared with that of lactating controls without breast cancer.

CONCLUSION

¹⁸F-FDG uptake in lactating tissue of PABC patients is markedly lower compared with the characteristically high physiological uptake among lactating patients without breast cancer. Consequently, breast tumors visualized by ¹⁸F-FDG uptake in PET/CT were comfortably depicted on top of the background ¹⁸F-FDG uptake in lactating tissue of PABC patients.

KEY POINTS

• FDG uptake in the breast is characteristically high among lactating patients regardless of the presence of an active malignancy other than breast cancer. • FDG uptake in non-affected lactating breast tissue is significantly lower among PABC patients compared with that in lactating women who do not have breast cancer. • In pregnancy-associated breast cancer patients, ¹⁸F-FDG uptake is markedly increased in the breast tumor compared with uptake in the non-affected lactating tissue, enabling its prompt visualization on PET/CT.