Incidental breast lesions identified by 18F-fluorodeoxyglucose-positron emission tomography

Somatostatin receptor-positive breast lesions on 68Ga-DOTATATE PET/CT

OBJECTIVE

This study sets out to evaluate patients with increased uptake in breast lesions on ⁶⁸Ga-DOTATATE PET/CT (DOTA PET) and determine the clinical significance of somatostatin receptor (SSTR) positive breast lesions.

METHODS

We retrospectively evaluated all patients with increased SSTR uptake in breast lesions on DOTA PET. Patients with physiological (e.g., lactation) or normal variant breast uptake (e.g., mild diffuse glandular uptake) were excluded. The maximum standard uptake value (SUVmax) was calculated using a manually drawn region of interest in the most intense uptake of breast lesions. All lesions were correlated with breast imaging, including mammography and ultrasonography. Histopathological correlation was performed if the lesion was suspicious for malignancy. Lesions were followed up radiologically (1-8 years).

RESULTS

Out of 1573 retrospectively analyzed DOTA PET scans, the incidence of SSTR + breast lesions was measured as 1.1% (n = 18); however, 4 of 18 patients were excluded due to the lack of final diagnosis of lesions. The median age was 35 (range 14-58 years), and all patients were female. The median SUVmax of SSTR + breast lesions was 5.2 (range 1.5-12.6) for a total of 14 patients. Twelve patients had a single SSTR + breast lesion, while 2 patients had multiple SSTR + lesions on bilateral breasts. In 6 patients, single SSTR + lesions were considered as fibroadenoma; in 2 patients, multiple SSTR + lesions were considered as metastases of NET, based on correlative breast imaging. In 6 patients, histopathological confirmation was needed for the final diagnosis. Histopathologic findings confirmed fibroadenoma in 4 patients by biopsy, in 1 patient with surgical removal of the lesion. The last patient who had a history of IDC was diagnosed with a recurrence of IDC with biopsy. The median SUVmax was 5.1 (range 1.5-9.4) for malignant breast lesions and 5.4 (range 2.2-12.6) for benign breast lesions.

CONCLUSION

SSTR + breast lesions on DOTA PET are rarely seen in clinical practice. Uptakes of breast lesions in our cases were variable and not useful for differential diagnosis of lesions. It seems that SSTR + breast lesions should be evaluated with clinical and radiological characteristics, and correlative breast imaging and/or histopathological verification should be performed for suspicious lesions to avoid misdiagnosis.

The frequency and malignancy rate of incidental focal breast lesions identified by 18F-fluorodeoxyglucose positron emission tomography

OBJECTIVE

To evaluate the frequency and malignancy rate of incidental focal uptake of 18F-fluorodeoxyglucose (FDG) in the breast on PET/computed tomography (CT).

MATERIAL AND METHODS

All PET/CT scan reports from a single institution from 2010 to 2017 were electronically searched for words or phrases related to FDG uptake in the breast. Potentially eligible PET/CT scans were manually reviewed for the presence of focal incidental findings in the breast, and a final diagnosis was established based on pathology, clinical examinations, and clinical follow-up.

RESULTS

A total of 19 551 PET/CT scans were reviewed, from which 66 patients (0.3%) presented with unexpected focal FDG-avid lesions of the breast. Fifty-three patients (80.3%) had follow-up evaluations. The final diagnosis showed malignancies in 38 patients. Thirty-four patients had biopsy-verified cancer (primary breast cancers, n = 30; metastasis, n = 4), and four patients with known lymphoma showed a tumour response in the breast after chemotherapy. The malignancy rate was 85.0% among patients who underwent biopsy (34 of 40 patients). The SUVmax was significantly higher in patients with a final malignant diagnosis (n = 38) than in those with a benign diagnosis (n = 15) (4.5 ± 2.9 vs. 2.7 ± 1.3, P = 0.03).

CONCLUSION

Incidental uptake of FDG in the breast was rare. However, the malignancy rate was high among these patients, particularly among patients who had a follow-up biopsy. We recommend biopsy or thorough follow-up in patients with incidental focal uptake of FDG in the breast.

<p>Metastasis of Ovarian Cancer to Breast: A Case Report and Review of Imaging Manifestations</p>

Metastasis of ovarian cancer to breast (MOCB) is rare, and the diagnosis is difficult due to the varied imaging manifestations. The objective of this paper is to report a special case of MOCB, review the imaging manifestations of MOCB and attempt to determine the characteristic imaging features that might be helpful in making the diagnosis and providing appropriate systemic therapy. A 40-year-old woman presented with a breast lesion six years after a diagnosis of ovarian serous cystadenocarcinoma. Ultrasound (US) and magnetic resonance imaging (MRI) examinations were performed; the final diagnosis was metastasis of ovarian serous cystadenocarcinoma to breast according to the histological examination and immunohistochemical examination after lumpectomy. Herein, we reviewed 41 cases diagnosed with MOCB, which include imaging of the metastatic breast lesion or a detailed description without imaging. In this review, we summarized that MOCB could present with calcifications (especially microcalcifications) on mammography (MM). MOCB presenting as inflammatory breast cancer usually shows swelling and skin thickening on MM and US, and increased fludeoxyglucose (FDG) uptake on positron emission tomography/computed tomography (PET/CT). These manifestations could be helpful in differentiating malignant tumors from benign ones, but it may still be difficult to distinguish between primary and metastatic tumors. The correct diagnosis of MOCB requires a combination of the clinical history of the primary tumor, careful clinical examination, radiology and anatomic pathological evaluation.

Correlation Between 18F-FDG PET/CT Findings and BI-RADS Assessment Using Ultrasound in the Evaluation of Breast Lesions: A Multicenter Study

RATIONALE AND OBJECTIVES

To analyze the correlation between ultrasound breast imaging reporting and data system (BI-RADS) category and fluorodeoxyglucose [¹⁸F] (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) findings and their value in breast lesion diagnosis.

MATERIALS AND METHODS

Cases involving hypermetabolic lesions identified by ¹⁸F-FDG PET/CT and ultrasound were retrospectively analyzed. The correlation between the maximum standardized uptake values (SUV_max) of the lesions and the BI-RADS grades was calculated. Histologic diagnosis or evidence at the end of a 2-year follow-up as the standard of truth were analyzed to determine the sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV) of the diagnostic methods. Area under the curve (AUC) of BI-RADS, SUV_max, and BI-RADS/SUV_max combined were obtained using receiver-operating characteristic curve (ROC) analysis.

RESULTS

Of 206 cases, 92 were benign and 114 were malignant. The difference between the SUV_max and the BI-RADS grades was statistically significant (p < 0.001). The critical value of the optimal SUV_max was 2.325, and the accuracy, sensitivity, specificity, PPV, and NPV were 84.5%, 91.2%, 76.1%, 82.5%, and 87.5%, respectively. For diagnosis using BI-RADS, these values were 85.9%, 98.2%, 70.7%, 80.6%, and 97.0%, respectively. ROC analysis of 206 breast lesions for distinguishing benign from malignant lesions yielded AUCs of 0.948, 0.896, and 0.977 for BI-RADS, SUV_max, and BI-RADS/SUV_max combined, respectively. The critical value of the optimal SUV_max in grade 3 and 4 lesions (as determined using BI-RADS) was 2.705, and the accuracy, sensitivity, specificity, PPV, and NPV were 82.6%, 77.8%, 85.7%, 77.8%, and 85.7%, respectively. For diagnosis using BI-RADS in cases with grade 3 and 4 lesions, these values were 68.5%, 94.4%, 51.8%, 55.7%, and 93.5%, respectively. In ROC analysis for distinguishing benign from malignant for BI-RADS grade 3-4 lesions, the AUC of BI-RADS, SUV_max, and BI-RADS/SUV_max combined were 0.731, 0.859, and 0.882, respectively.

CONCLUSION

Both ¹⁸F-FDG PET/CT and ultrasound-dependent BI-RADS grading are effective for diagnosing breast lesions. However, in cases of BI-RADS grades 3 and 4, ¹⁸F-FDG PET/CT has better specificity and may be useful for further differential diagnosis.

Prevalence of focal incidental breast uptake on FDG-PET/CT and risk of malignancy: a systematic review and meta-analysis

Background

FDG-PET/CT is increasingly used for oncologic and inflammatory diseases. Focal incidental FDG uptake occurs rarely in breast tissue but has often significant consequences. This study aimed to systematically review literature regarding focal incidental breast uptake (FIBU) on FDG-PET/CT in order to yield an update on the prevalence and risk of malignancy for FIBU.

Methods

A systematic search for relevant articles published between 2012 and 2018 was performed through MEDLINE, Embase, and Cochrane databases. Studies addressing the detection of FIBU in patients without a previous history of breast malignancy were included. The QUADAS-2 was used for quality assessment, and eligible data were pooled using a fixed-effects model. I² was calculated for the heterogeneity between studies.

Results

Eight studies containing 180,002 scans were included in the systematic review. The median prevalence of FIBU for both genders was 0.52% (range 0.18–22.5%). Prevalence for women was mentioned separately in five studies and varied from 0.51 to 23.5%. One study reporting a high prevalence was based on patients being staged for known malignancy, and the word “breast” was used in the search, which may have caused selection bias. Data from four studies were eligible for meta-analysis. A high degree of heterogeneity was observed for prevalence data (I² of 97.5%), while moderate heterogeneity was observed for data on malignancy risk assessment (I² of 62.8%). The pooled prevalence of FIBU in women was 0.61% (range 0.56–0.66%), and the pooled prevalence of malignancy of FIBUs was 38.7% (range 34.4–43.0%). The most commonly detected malignancy was invasive ductal carcinoma.

Conclusion

FIBU occurs rarely on FDG-PET/CT for female patients but yields a high risk of malignancy according to the results of published papers. Therefore, it should be considered relevant to further elucidate patients with incidentally detected FDG uptake in breast in clinical practice.

Electronic supplementary material

The online version of this article (10.1186/s41824-019-0063-5) contains supplementary material, which is available to authorized users.

Incidence and outcomes of incidental breast lesions detected on cross-sectional imaging examinations

The aim of this study was to determine the frequency and outcomes of incidental breast lesions detected on nonbreast specific cross-sectional imaging examinations. A retrospective review of the medical records was performed to identify all patients without a known history of breast cancer, who had an incidentally discovered breast lesion detected on a nonbreast imaging examination performed at our institution between September 2008 and August 2012 for this IRB-approved, HIPAA compliant study. Outcomes of the incidental lesions were determined by follow-up with dedicated breast imaging (mammography, breast ultrasound, and/or breast MRI) or results of biopsy, if performed. Imaging modality of detection, imaging features, patient age, patient location at the time of the nonbreast imaging examination, type of follow-up, and final outcome were recorded. Rates of malignancy were also calculated, and comparison was made across the different cross-sectional imaging modalities. Kruskal-Wallis and Fisher's exact tests were used to identify factors associated with an increased rate of malignancy. Logistic regression was used to model the risk of malignancy as a function of continuous predictors (such as patient age or lesion size); odds ratios and 95% confidence intervals were obtained. A total of 292 patients with incidental breast lesions were identified, 242 of whom had incidental lesions were noted on computed tomography (CT) studies, 25 on magnetic resonance imaging (MRI), and 25 on positron emission tomography (PET). Although most of the incidental breast lesions were detected on CT examinations, PET studies had the highest rate of detection of incidental breast lesions per number of studies performed (rate of incidental breast lesion detection on PET studies was 0.29%, compared to 0.10% for CT and 0.01% for MRI). Of the 121 of 292 (41%) patients who received dedicated breast imaging work-up at our institution, 40 of 121 (33%) underwent biopsy and 25 of 121 (21%) had malignancy. There was a significantly increased rate of malignancy in older patients (odds ratio: 1.05, 95% CI: 1.02-1.093; P = .006). Additionally, patients with PET-detected incidental breast lesions had a significantly higher rate of malignancy (55%), compared to patients with CT-detected (35%) and MRI-detected (8%) incidental breast lesions (P = .038). The rate of malignancy upon follow-up of incidental breast lesions detected on nonbreast imaging examinations in this retrospective study was 21%, supporting the importance of emphasizing further work-up of all incidentally detected breast lesions with dedicated breast imaging. Additionally, we found that PET examinations had the highest rate of detection of incidental breast lesions and the highest rate of malignancy, which suggests that PET examinations may be more specific for predicting the likelihood of malignancy of incidental breast lesions, compared to CT and MRI.

[Imaging diagnostics of breast metastases from extramammary tumors]

Breast metastases of solid extramammary tumors are very rare in comparison to primary malignancies of the breast and account for only 0.33-6.3% of all malignant neoplasms of the breast. The most common primary tumors are malignant melanoma, distant sarcomas, lung cancer, ovarian cancer, renal cell cancer and thyroid cancer in decreasing order of frequency. This review article summarizes the clinical features and the different imaging findings of breast metastases from different extramammary solid tumors. Breast metastases are often incidental findings in computed tomography (CT) or positron emission tomography CT (PET-CT) imaging. Mammography shows two different imaging patterns, namely focal lesions and diffuse architectural distortion with skin thickening. Breast metastases presenting as focal masses usually occur as solitary and more rarely as multiple round lesions with a smooth edge boundary. Associated calcifications are rare findings. Diffuse architectural distortion with skin thickening is more common in breast metastases from most gastric tumors, ovarian cancer and rhabdomyosarcoma. Using ultrasound most lesions are hypoechoic, oval or round with smooth boundaries and posterior acoustic enhancement. The magnetic resonance imaging (MRI) criteria of breast metastases show an inconstant signal behavior that cannot be safely classified as benign or malignant. In summary, in patients with known malignancies the presence of breast metastases should be considered even with imposing clinically and radiologically benign findings.

Incidental Breast Lesions Identified by (18)F-FDG PET/CT: Which Clinical Variables Differentiate between Benign and Malignant Breast Lesions?

Purpose

The aim of our study was to evaluate the risk of malignancy and to determine which clinical variables differentiate between benign and malignant focal breast lesions found incidentally on ¹⁸F-flourodeoxyglucose positron emission tomography and computed tomography (FDG PET/CT).

Methods

From March 2005 to October 2011, 21,224 women with no history of breast cancer underwent FDG PET/CT at three university-affiliated hospitals. We retrospectively identified 214 patients with incidental focal hypermetabolic breast lesions and grouped them into benign and malignant lesion groups. Of the 214 patients, 82 patients with 91 lesions were included in this study. All lesions were confirmed histologically or were assessed by follow-up imaging for greater than 2 years. The patient age, maximum standardized uptake value (SUV_max), lesion size on ultrasonography (US), and Breast Imaging-Reporting and Data System (BI-RADS) category on US in conjunction with mammography were compared between the groups. Multivariate logistic regression analysis was used to identify independent factors associated with malignancy.

Results

The risk of malignancy was 29.7% (27/91) in breast incidentalomas detected by FDG PET/CT. The univariate analysis showed that the patient age, SUV_max, tumor size, and BI-RADS category differed significantly between the malignant and benign groups. The multivariate analysis showed that the BI-RADS category was the only significant factor differentiating benign from malignant lesions (p=0.002).

Conclusion

BIRADS category based on US in conjunction with mammography was the only useful tool to differentiate between malignant and benign lesions in breast incidentalomas on FDG PET/CT.

Multicentric study on ¹⁸F-FDG-PET/CT breast incidental uptake in patients studied for non-breast malignant purposes

AIM

Our study has aimed to establish the prevalence and pathological nature of fluorine-18-fluorodeoxyglucose ((18)F-FDG) breast incidental uptake (BIU) in patients studied for non-malignant breast tumours and then to compare our data obtained in three Italian nuclear medicine centres with those available in literature.

MATERIAL AND METHODS

We retrospectively evaluated 42,927 (18)F-FDG-PET/CT scans performed on patients studied in three Italian Nuclear Medicine Centres. All patients underwent (18)F-FDG-PET/CT for oncologic purposes not related to breast disease.

RESULTS

Among 42,927 scans, a BIU was identified in 79 (0.18%) patients, 75 (95%) female and 4 (5%) male with an average age of 62 ± 17 years. Twenty-five out of 35 (71.5%) BIUs were malignant and 10/35 (28.5%) benign. Among the 25/35 incidentalomas that were malignant, 12/25 (48%) were infiltrating ductal carcinoma, 5/25 (20%) ductal carcinoma (infiltrating and in situ), 4/25 (16%) lobular carcinoma, 2/25 (8%) ductal carcinoma in situ and 2/25 (8%) were metastases from the primary tumour under investigation. Of the 10 BIUs that were benign in the histological examination, after further investigations it was found that 9/10 (90%) were fibroadenomas and 1/10 (10%) was a benign lesion not better specified. The lesion to liver or to blood-pool SUVmax ratio in malignant lesions is significantly higher than in benign ones.

CONCLUSIONS

Our multicenter study demonstrates that, although they are uncommon, BIUs show a high percentage of malignancy and therefore requires further research.

Metastases to the breast from extramammary malignancies - PET/CT findings

Detection of incidental malignant lesions in the breast has a significant clinical impact not only on healthy individuals but also on patients with known malignant disease. This review describes a spectrum of metastatic breast lesions incidentally detected by FDG PET-CT at staging that may be misinterpreted as second primary malignancy. The common non-mammary malignancies that metastasize to the breast include melanoma, hematopoietic malignancies and epithelial cancers. We present the FDG PET-CT features of incidental non-mammary metastases to the breast that may help distinguish primary breast cancer from metastatic disease and aid in the management of patients with a known malignancy.

The role of the breast radiologist in evaluation of breast incidentalomas detected on 18-fludeoxyglucose positron emission tomography/CT

OBJECTIVE

To evaluate the significance of incidentally discovered breast lesions on 18-fludeoxyglucose ((18)F-FDG) positron emission tomography (PET)/CT.

METHODS

6050 (18)F-FDG PET/CT studies, performed between January 2009 and February 2012, were retrospectively reviewed. 55 lesions in 50 patients were identified. Additional work-up, including mammography, ultrasound, follow-up (18)F-FDG PET/CT and biopsy, was available for 39 incidental breast lesions in 36 patients. All patients were female, with mean age 61.5 years (range 36-90 years). The maximum standardised uptake value (SUVmax), CT size and CT Breast Imaging Reporting and Data System (BI-RADS®) scores were compared between the malignant and the benign subgroups, using the unpaired t-test and Fisher's exact test. Tests were two-sided and a p-value of <0.05 was considered to be significant.

RESULTS

Incidental breast lesions were identified in 50 (0.8%) of 6050 (18)F-FDG PET/CT studies. 21 (53.8%) of the 39 breast incidentalomas were malignant on biopsy or imaging, of which 15 (38.5%) represented a second primary breast cancer. A statistically significant difference in the mean SUVmax between malignant and benign breast lesions was observed (p=0.021). Malignancy was significantly more common in the CT BI-RADS Category 4 or greater groups (76.2%; p=0.0105).

CONCLUSION

Incidental breast lesions detected at (18)F-FDG PET/CT are uncommon. When detected, however, they may represent malignancy in up to 53.8% of cases.

ADVANCES IN KNOWLEDGE

SUVmax and CT findings at (18)F-FDG PET/CT can assist with differentiating benign and malignant breast conditions, guiding further evaluation with dedicated breast imaging. Review of (18)F-FDG PET/CT-detected breast lesions by a breast radiologist may be helpful in determining the need for and correlation with further breast imaging. Radiologists and nuclear medicine physicians should be cognisant of breast pathology when reporting (18)F-FDG PET/CT image data sets.

Mammography and ultrasonography evaluation of unexpected focal 18F-FDG uptakes in breast on PET/CT

BACKGROUND

Unexpected focal 18F-FDG breast uptakes are occasionally identified on PET/CT due to its increased use for cancer staging and follow-up. The need for their characterization has been suggested.

PURPOSE

To retrospectively evaluate the diagnostic value of ultrasonography (US) in distinguishing benign from malignant lesions for unexpected focal 18F-FDG uptakes in breast on PET/CT scans.

MATERIAL AND METHODS

Between April 2004 and January 2010, 27 focal 18F-FDG breast uptakes in 27 patients (age range 33-62 years; mean age 46 years) among 5214 patients who had undergone PET/CT scans were retrospectively analyzed. The American College of Radiology (ACR) Breast Imaging-Reporting and Data System (BI-RADS) final assessment categories of the US and the maximum standardized uptake values (SUVs) of the lesions were compared between the benign and malignant lesions.

RESULTS

Of the 27 lesions, 15 (56%) lesions were malignant. The rate of malignancy, according to the final assessment category on the US, was 0% (0 of 6) for category 3, 60% for category 4 (9 of 15), and 100% (6 of 6) for category 5 (P = 0.001). The US evaluation revealed a sensitivity of 100% (15 of 15) and a specificity of 50% (6 of 12). The average maximum SUV of the malignant lesions was greater than that of the benign lesions (4.12 ± 1.94 vs. 1.94 ± 0.82; P = 0.001).

CONCLUSION

US evaluation of unexpected focal 18F-FDG uptakes on PET/CT scans can accurately distinguish benign lesions from malignant lesions.