# A Novel Computer-Aided-Diagnosis System for Breast Ultrasound Images Based on BI-RADS Categories
\begin{table}
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**Assessment** & **Management** & **Likelihood of Cancer** \\ \hline Category 0:Incomplete—Need Additional Imaging Evaluation & Recall for additional imaging & N/A \\ \hline Category 1: Negative & Routine screening & Essentially 0\% likelihood of malignancy \\ \hline Category 2: Benign & Routine screening & Essentially 0\% likelihood of malignancy \\ \hline Category 3: Probably Benign or Continued Surveillance & Short-interval (6-month) follow-up & \textgreater{} 0\% but \(\leq 2\%\) likelihood of malignancy \\ \hline Category 4: Suspicious & Tissue diagnosis & \textgreater{} 2\% but \(\leq 95\%\) likelihood of malignancy \\ \hline Category 4A: Lowsuspicion for malignancy & Tissue diagnosis & \textgreater{} 2\% to \(\leq 10\%\) likelihood of malignancy \\ \hline Category 4B: Moderate suspicion for malignancy & Tissue diagnosis & \textgreater{} 10\% to \(\leq 50\%\) likelihood of malignancy \\ \hline Category 4C: High suspicion for malignancy & Tissue diagnosis & \textgreater{} 50\% to \(\leq 95\%\) likelihood of malignancy \\ \hline Category 5: Highly Suggestive of Malignancy & Tissue diagnosis & \textgreater{} 95\% likelihood of malignancy \\ \hline Category 6: Known Bios-Proven Malignancy & Surgical excision when clinically appropriate & N/A \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Concordance between BI-RADS assessment categories and management recommendations [1]. In Table 2, the shape category represents the shape of mass including: round, oval, or irregular. Orientation refers to the lesion's long axis relative to the skin; the descriptors for the mass margin are circumscribed or non-circumscribed, which in non-circumscribed margins include micro-lobulated, indistinct, angular, and speculated; the descriptors for the mass echo pattern rely on tissue having various reference educetures; the posterior feature refers to the attenuation characteristics of a mass relative to its acoustic transmission. In other words, BI-RADS provides a uniform standard for the interpretation of a breast image regarding the breast lesion--whether there exists a tumor; and evaluating the shape regularity of the mass, the distinction degrees of the non-circumscribed, the variabilities of the reference educetxture, the variabilities of the posterior feature, etc. (See Figure 1). \begin{table}
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**Category** & **Descriptors** & **Description** \\ \hline \multirow{3}{*}{Shape} & Oval Round Irregular & Elliptical or egg-shaped. Spherical, ball-shaped, circular. Neither round or oval in shape. \\ \cline{2-3}  & Parallel Not parallel & Long axis of lesion parallels the skin line. Long axis, not orientation along the skin line. \\ \hline \multirow{6}{*}{Margin} & Circumscribed & A margin that is well defined or sharp, with an abrupt transition between the lesion and surrounding tissue. The mass has one or more of the following features: indistinct, angular, microlobulated or speculated. No clear demarcation between a mass and its surround tissue. \\ \cline{2-3}  & - Angular & Some or all of the margin has sharp corners, often forming acute angles. Short cycle undulations impact a scalloped appearance to the margin of the mass. \\ \cline{2-3}  & - Spiculated & Margin is formed or characterized by sharp lines projecting from the mass. \\ \hline \multirow{6}{*}{Echo pattern} & Anechoic Hyperechoic Complex cystic and solid Hypoechoic & Without internal echoes. Having increased echogenicity relative to fat or equal to fibroglandular tissue. Mass contains both anechoic and echogenic components. Defined relative to fat; masses are characterized by low-level echoes. \\ \cline{2-3}  & Isoechoic Heterogeneous & Having the same echogenicity as fat. \\ \cline{2-3}  & No posterior features Enhancement Shadowing & The breasts are heterogeneously dense, which may obscure small masses \\ \cline{2-3}  & Combined pattern & No posterior shadowing or enhancement.