A simple classification system (the Tree flowchart) for breast MRI can reduce the number of unnecessary biopsies in MRI-only lesions
A simple classification system (the Tree flowchart) for breast MRI can reduce the number of unnecessary biopsies in MRI-only lesions
Ramona Woitek 0 1
Claudio Spick 0 1
Melanie Schernthaner 0 1
Margaretha Rudas 0 1
Panagiotis Kapetas 0 1
Maria Bernathova 0 1
Julia Furtner 0 1
Katja Pinker 0 1
Thomas H. Helbich 0 1
Pascal A. T. Baltzer 0 1
0 Clinical Institute of Pathology, Medical University of Vienna , Vienna , Austria
1 Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna , Vienna , Austria
2 Pascal A. T. Baltzer
Objectives To assess whether using the Tree flowchart obviates unnecessary magnetic resonance imaging (MRI)-guided biopsies in breast lesions only visible on MRI. Methods This retrospective IRB-approved study evaluated consecutive suspicious (BI-RADS 4) breast lesions only visible on MRI that were referred to our institution for MRIguided biopsy. All lesions were evaluated according to the Tree flowchart for breast MRI by experienced readers. The Tree flowchart is a decision rule that assigns levels of suspicion to specific combinations of diagnostic criteria. Receiver operating characteristic (ROC) curve analysis was used to evaluate diagnostic accuracy. To assess reproducibility by kappa statistics, a second reader rated a subset of 82 patients. Results There were 454 patients with 469 histopathologically verified lesions included (98 malignant, 371 benign lesions). The area under the curve (AUC) of the Tree flowchart was 0.873 (95% CI: 0.839-0.901). The inter-reader agreement was almost perfect (kappa: 0.944; 95% CI 0.889-0.998). ROC analysis revealed exclusively benign lesions if the Tree node was ≤2, potentially avoiding unnecessary biopsies in 103 cases (27.8%).
Magnetic resonance imaging; Breast cancer; Scoring system; Image-guided biopsy; ROC curve
ACR BI-RADS ADC AUC ben
Breast lesions rated as suspicious for cancer according to the
American College of Radiology Breast Imaging and
Reporting Data System (ACR BI-RADS) (e.g. assigned an
ACR BI-RADS ≥ 4 category) that were detected on breast
magnetic resonance imaging (MRI) require tissue sampling
and histopathological workup [1–3]. Unless these lesions are
visible on other imaging modalities, they require dedicated
MRI-guided, vacuum-assisted breast biopsy (VABB) to
provide representative tissue sampling [1, 2, 4]. As reflected by
positive predictive values of MRI-guided biopsies below 50%
in the literature [5–8], a relevant number of benign lesions
visible on MRI undergo unnecessary VABBs that can
potentially be avoided. MR-guided VABB is a safe and accurate
procedure in the diagnostic workup, but its application is
limited by availability, relatively high costs compared to other
biopsy techniques, and the necessity to administer
gadolinium-containing contrast agent intravenously [9].
Although minimally invasive, MR-guided biopsies carry a
low risk for complications, such as infection or bleeding [9].
There is general consent that unnecessary biopsies should be
avoided [10] by ruling out malignancy based on imaging
features. Numerous efforts have been made to decrease the
number of false-positive results in standard breast MRI using
additional imaging techniques, such as diffusion-weighted
imaging (DWI), MR spectroscopy (MRS) and positron
emission tomography (PET), or sophisticated evaluation of
dynamic contrast-enhanced MRI [11–17]. Although these
approaches may increase specificity, there are several issues
regarding standardization, as well as time and cost effectiveness.
It would be thus desirable if such an increase in specificity
could be achieved using standard breast MRI sequences only.
To report imaging features and indicate suspicion for
malignancy, ACR BI-RADS is the most widely used standard. It
facilitates communication among physicians with its
structured common language and standardized terminology for
image interpretation and reporting. However, it lacks precise
rules according to which to assign imaging features (i.e. lesion
morphology and functional contrast enhancement kinetics) to
diagnostic categories. Therefore, using ACR BI-RADS, the
inter-reader agreement remains moderate, diagnostic accuracy
is variable, a relevant number of unnecessary biopsies are
performed in benign lesions, the inter-reader agreement
remains moderate, and diagnostic accuracy is variable [18–22].
Fig. 1 Tree flowchart following the description by Marino et al. [24].
Terminal nodes are hierarchically ordered (1–11) and represent increasing
probabilities of malignancy
To complement the ACR BI-RADS lexicon and to increase
specificity, Baltzer et al. proposed a simple classification
system (the Tree flowchart) for breast MRI to differentiate benign
and malignant lesions on breast MRI [23].The Tree flowchart
combines five diagnostic criteria (the root sign, enhancement
kinetics, lesion margins, internal enhancement pattern and
ipsilateral oedema; Fig. 1, Table 1) to assign a diagnostic score
to each les (...truncated)