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. Author manuscript; available in PMC: 2021 Jan 1.
Published in final edited form as: Abdom Radiol (NY). 2020 Jan;45(1):24–35. doi: 10.1007/s00261-019-02306-7

Fig. 6.

Fig. 6

Examples of misclassified LI-RADS v2014 observations on external datasets: (a–d) EXT-CT and (e, f) EXT-MR. Each plot title includes the dataset name, observation diameter, ground truth, and predicted LI-RADS category. Pre-contrast, late arterial, and delayed phase cropped images are displayed from left to right, and the rightmost bar plot shows the output probability for each LI-RADS category. (a) An LR-4 observation with a diameter of 13 mm was misclassified as LR-5 by the model, which falls in the cell having two options, LR-4 and LR-5 according to the LI-RADS version 2014 diagnostic table; this, however, should be categorized as LR-5 by the updated LI-RADS version 2018. Probabilities for LR-1/2 and LR-3 were low (2% and 6%, respectively). (b) A case of nodule-like arterial phase hyperenhancement with a diameter of 9 mm had a ground truth label of LR-3 but was misclassified as LR-5 by the model. A major feature of arterial hyperenhancement is evident, whereas washout or enhancing capsule appearance is not apparent. However, the central part of the delayed phase image might appear slightly hypodense compared with the peripheral area. The probability for LR-1/2 was only 3%. (c) A small cyst had a ground truth label of LR-1/2 but was misclassified as LR-3 by the model. Cropped low resolution image due to small observation size may make the observation blurry and hard to be correctly categorized (specifically on late arterial phase image for this particular case). Probabilities for LR-4 and LR-5 were low (8% and 9%, respectively). (d) A 6 mm observation with arterial hyperenhancement had a ground truth label of LR-3 but was misclassified as LR-1/2 by the model, where the probabilities for LR-1/2 and LR-3 was almost the same. Interobserver variability for such observations probably exist even among experts depending on their experience. (e) A 19 mm HCC with a ground truth label of LR-5 was misclassified as LR-4 with a probability of 0.88. HCC exhibited all of the major imaging features: arterial hyperenhancement, washout, and enhancing capsule.

Abbreviations: HCC, hepatocellular carcinoma; LI-RADS and LR-, the Liver Imaging Reporting and Data System