Results
Diagnostic Performance
Pathological examinations showed residual disease in 53 of the 65 lesions.
Pathological complete response rate was 18% (12/65).
15 (23%) of the 65 lesions showed no enhancement on dynamic MR images and were evaluated as having no residual disease.
10 of them had no residual disease on pathology and were correctly evaluated (negative predictive value 0.67).
50 (77%) of the 65 lesions showed enhancement on dynamic MR images and were evaluated as having residual disease.
48 of them had residual disease on pathology and were correctly evaluated (positive predictive value 0.96)
5 lesions showed a false negative result and 2 did a false positive result.
Sensitivity was 0.91 and specificity was 0.83.
28 of the 53 residual lesions had invasive tumors and 8 did intraductal tumors and 17 did both on pathology and the sensitivity for these residual lesions were 0.93,
0.75 and 0.94 respectively: the lesions composed of intraductal tumors alone showed lower sensitivity.
Table 1: Diagnostic performance and pathology
Early versus late phase images
When late phase images were compared with early phase images in the depiction of residual disease,
39 (74%) of the 53 residual lesions were depicted more clearly on late phase images than early phase images.
Table 2: Early phase vs late phase
MR appearances of residual lesions
Mass
36 of the 48 residual lesions depicted by MR imaging were depicted as a mass.
Many of the mass lesions were solitary and had an irregular shape and margin,
heterogeneous enhancement,
and a persistent enhancement pattern.
Number: solitary; n=27,
multiple; n=9
Shape: irregular; n=25,
oval; n=9,
round; n=2
Margin: irregular; n=29,
spiculated; n=4,
circumscribed; n=3
Internal enhancement: heterogeneous; n=33,
rim; n=3
TIC: persistent; n=20,
plateau; n=4,
washout; n=12
Non-mass enhancement
12 residual lesions were depicted as non-mass enhancement.
Most of the lesions had focal area distribution and heterogeneous internal enhancement.
Distribution: focal area; n=11,
linear; n=1
Internal enhancement: heterogeneous; n=9,
clumped; n=3
In the 48 residual lesions depicted by MR imaging,
the lesions composed of invasive tumors with or without intraductal tumors tended to be depicted as a mass and the lesions composed of intraductal tumors alone as non-mass enhancement.
Table 3: Mass and non-mass enhancement
Representative cases
Case 1.
True negative case - Invasive cancer 80 y.o.
woman
Pre-chemotherapy late phase sagittal image (Fig.
2) shows a large irregular-shaped mass (arrow).
No contrast enhancement is seen at the tumor site (arrow) on a post-chemotherapy late phase sagittal image (Fig.
3).
No residual disease was present on pathology.
Fig. 2: Pre-chemotherapy late phase sagittal image.
A large irregular-shaped mass (arrow) is seen.
Fig. 3: Post-chemotherapy late phase sagittal image.
No contrast enhancement is seen at the tumor site (arrow).
Case 2. True positive case - Invasive cancer 44 y.o.
woman
Pre-chemotherapy late phase maximum intensity projection (MIP) image (Fig.
4) shows a large irregular-shaped mass (arrows).
Residual invasive cancer is depicted as an irregular-shaped mass (arrow) on a post-chemotherapy MIP image (Fig.
5).
Fig. 4: Pre-chemotherapy late phase MIP image.
A large irregular-shaped mass (arrows) is seen.
Fig. 5: Post-chemotherapy late phase MIP image.
Residual invasive cancer is depicted as an irregular-shaped mass (arrow).
Case 3.
False negative case - Invasive cancer 49 y.o.
woman
Pre-chemotherapy late phase axial image (Fig.
6) shows an oval-shaped mass with rim enhancement (arrows).
Post-chemotherapy late phase axial image (Fig.
7) shows no contrast enhancement at the tumor site (arrow).
Surgical specimen (Fig.
8) shows 3 mm residual invasive cancer (arrow).
Fig. 6: Pre-chemotherapy late phase axial image.
An oval-shaped mass with rim enhancement (arrows) is seen.
Fig. 7: Post-chemotherapy late phase axial image.
No contrast enhancement is seen at the tumor site (arrow).
Fig. 8: Surgical specimen.
3 mm residual invasive cancer (arrow) is seen on pathology.
Case 4.
False positive case - Invasive cancer 53 y.o.
woman
Pre-chemotherapy 2nd early phase axial image (Fig.
9) shows an oval-shaped mass (arrow).
Post-chemotherapy late phase axial image (Fig.
10) shows linear-shaped non-mass enhancement (arrow) at the tumor site.
Pathological examination showed fibrous scar tissue at the corresponding site.
Fig. 9: Pre-chemotherapy 2nd early phase axial image.
An oval-shaped mass (arrow) is seen.
Fig. 10: Post-chemotherapy late phase axial image.
Linear-shaped non-mass enhancement (arrow) is present at the tumor site.