How to deal with architectural distortions on DBT?


Researchers led by Dr. Lilian Wang of Northwestern Medicine in Chicago investigated the usefulness of DBT in cases of women with multiple ipsilateral or contralateral distortions on their scans. While these distortions may be indicative of a high-risk case, they are not necessarily indicative of a malignant disease, they said in a study published July 27 in American Journal of Radiology.

“Data from this study demonstrated variation in pathological outcomes in patients with multiple architectural distortions, leading to complex management decisions,” Wang said. “For patients with multiple architectural distortions, biopsy of all areas may be warranted given the variation in pathologic diagnoses.”

While research has shown that DBT detects more cancers and reduces recall rates compared to conventional mammography, the technology can also reveal subtle findings like architectural distortions that can present interpretation challenges. A 2021 study reported that such a distortion on DBT has a pooled positive predictive value (PPV) for malignancy of 34.6%, suggesting that tissue sampling may be needed.

“This becomes problematic in patients with multiple architectural distortions, as it may not be possible or desirable to biopsy all visualized areas,” Wang said.

However, the management of architectural distortions in patients remains a mystery to radiologists. The researchers noted that there is high interobserver variability in this area and that parenchymal variation can be interpreted as distortion or as normal parenchyma.

Ultrasound-guided biopsy, MRI, and excisional biopsy with DBT-guided needle localization are some options that have been suggested. But the researchers found a lack of data on histopathological findings in patients with multiple distortions.

Therefore, Wang and colleagues wanted to compare pathological outcomes between single and multiple architectural distortions identified on DBT.

(A) Craniocaudal and (B) mediolateral oblique DBT images show two areas of architectural distortion in the outer upper left breast (circles) that persisted on additional diagnostic tomosynthesis images (not shown). (C) Transverse grayscale ultrasound image of the outer upper breast shows an irregular hypoechoic mass with associated architectural distortion at 12:30 (arrow), consistent with posterior architectural distortion. No sonographic correlate was identified for anterior architectural distortion. Ultrasound-guided biopsy of the posterior distortion revealed malignancy (invasive lobular carcinoma). Tomosynthesis-guided biopsy of the anterior distortion revealed benign pathology (stromal fibrosis).

The study authors reviewed retrospective data from 402 women collected between 2017 and 2019. Of the total, 372 women had a single architectural distortion (145 benign, 121 high-risk, 105 malignant, 1 other) and 30 women had multiple visualized distortion. Of these two groups, 66 women had a biopsied architectural distortion (10 benign, 35 high-risk, 21 malignant).

Distortions were characterized as high risk if they had features such as atypical ductal hyperplasia, radial scar, papilloma, flat epithelial atypia, and lobular neoplasia (atypical lobular neoplasia or lobular carcinoma in situ). Malignant distortions were defined as ductal carcinoma in situ (DCIS), invasive ductal carcinoma, and invasive lobular carcinoma (ILC).

Characterization of lesions based on the number of architectural distortions on DBT scans
Single Distortion Multiple distortions p-value
Benign 39% 15.2% N / A
High risk 32.5% 53% p = 0.002
clever 28.2% 31.8% p=0.56
High Risk + Malignant 60.7% 84.8% p = 0.001

*Data is based on a per lesion analysis.

Wang et al found that the frequency of malignancy did not differ on a statistically significant basis between scans with multiple versus single distortions, either by lesion or by patient. While the frequency of high-risk pathologies was significantly higher for multiple than single distortions on a per-lesion basis, this was not on a per-patient basis (p = 0.07).

In addition, the frequency of high-risk or malignant pathologies was significantly higher for multiple than single distortions, both at the lesion level (84.8% vs. 60.7%, p

The researchers also found that for patient-related characteristics, the presence of single or multiple distortions was not independently related to malignancy (p=0.51). Moreover, in patients with multiple distortions, the most aggressive pathology among all distortions was not related to the number of distortions (p = 0.73).

A total of 24 women had at least two ipsilateral biopsied architectural distortions. Of these, eight saw ipsilateral areas varying in terms of the most aggressive pathology. In five out of 10 women with contralateral biopsy distortions, the team found that the contralateral areas varied in the most aggressive pathology.

The study authors wrote that these findings could help guide the management of architectural distortions visualized by DBT, including multiple distortions. However, Wang said that more data and larger studies are needed to help establish management guidelines in this context.

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