Table 1.
Patient Demographics and Tumour Characteristics.
Fig 1.
A false positive lymph node due to thickened cortex was true negative on DWI (A-F).
Imaging of a 41-year-old female with a BI-RADS 5 lesion in the right breast. An axillary LN with a cortical thickness of 3.9 mm was core biopsied. Final histology revealed a 30 mm, grade 3, T2 ductal carcinoma; the SLNB was benign. No recurrence occurred over a two-year follow-up. The LN was false positive on T1-weighted MRI (A) and US (B) due to thickened cortex, while DWI b = 800 (C,D) was true negative with ADC = 1.24 x 10–3 mm2/s (cut-off 0.812 x 10–3 mm2/s). The importance of correct positioning of the ROI and ROI’s information (including minimum value) is illustrated at the area of fatty hilar lobulation (E). False-positive ADCs can be obtained from the cortical area medially if the morphological images are not evaluated or the minimum value of 0 is accepted or is not available at the time of evaluation (F).
Fig 2.
Final histopathology indicating true-positive US and DWI findings with metastases (A-F). Imaging of a 62-year-old female with a 31 mm BI-RADS 5 tumour in the right breast. LN that was targeted for core biopsy on axillary US measured 12 x 29 mm with a cortical thickness of 9 mm. STIR, DWI, US and ADC (A,B,D,E) images of this histopathologically confirmed metastatic LN having ADCs of 0.436 x 10−3 mm2/s and 0.789 x 10−3 mm2/s according to two observers; both of these values were below the threshold of 0.812 x 10−3 mm2/s. Histolopatholocigal images (C,F) of core biopsied LN with visual biopsy channel (arrow). Final histopathology indicated true-positive US and DWI findings with metastatic involvement.
Fig 3.
Receiver operating characteristics of readings with two types of ROI information (n = 33).
First reading with no information on minimum value in the ROI (standard ROI), second reading with information of the mean, standard deviation, minimum, and maximum values (detailed ROI) improved the accuracy. Diagonal segments result from ties.
Fig 4.
The ADC readings were congruent between observers (A) and (B).
Receiver operating characteristics (A) and scatter plot (B) of readings from two observers (n = 56) with ROIs including information of the mean, standard deviation, minimum, and maximum values. Diagonal segments result from ties.
Table 2.
Performance Measures of 3.0-T DWI MRI.
Table 3.
Imaging Features and ADC values of Histologically Confirmed Metastatic Axillary LNs.
Table 4.
Comparison of ADC values from Breast Tissue, Malignant Breast Lesions, Metastatic LNs and Diagnostic Performance of DWI.