Dedicated breast CT: initial clinical experience

Abstract

Purpose: To prospectively and intraindividually compare dedicated breast computed tomographic (CT) images with screen-film mammograms.

Materials and methods: All patient studies were performed according to protocols approved by the institutional review board and Radiation Use Committee; informed consent was obtained. A breast CT scanner prototype was used to individually scan uncompressed breasts in 10 healthy volunteers (mean age, 52.1 years) and 69 women with Breast Imaging Reporting and Data System category 4 and 5 lesions (mean age, 54.4 years). In women with lesions, breast CT images were compared with screen-film mammograms by an experienced mammographer and ranked with a continuous scale of 1-10 (score 1, excellent lesion visualization with CT and poor visualization with mammography; score 5.5, equal visualization with both modalities; and score 10, poor visualization with CT and excellent visualization with mammography). A Wilcoxon signed rank procedure was used to test the null hypothesis that ratings were symmetric at about a score of 5.5 for the entire group and for distinguishing microcalcifications versus masses and other findings and benign versus malignant lesions and for effect of breast density on lesion visualization. Women were asked to compare their comfort during CT with that during mammography on a continuous scale of 1-10. With a Wilcoxon signed rank procedure, the null hypothesis that comfort ratings were symmetric about a score of 5.5 (equal comfort with CT and mammography) was tested.

Results: Overall, CT was equal to mammography for visualization of breast lesions. Breast CT was significantly better than mammography for visualization of masses (P = .002); mammography outperformed CT for visualization of microcalcifications (P = .006). No significant differences between CT and mammography were seen among benign versus malignant lesions or for effect of breast density on lesion visualization. Subjects found CT significantly more comfortable than mammography (P < .001).

Conclusion: Some technical challenges remain, but breast CT is promising and may have potential clinical applications.

(c) RSNA, 2008.

Figures

Figure 1:

Schematic drawing of dedicated breast CT scanner shows patient lying prone with breast pendant through table aperture. Breast CT source and detector rotate 360° around patient's breast.

Figure 2a:

(a) Craniocaudal screen-film mammogram of right breast shows 4-mm IDC (arrow). (b) Coronal CT scan in same woman in same breast shows 4-mm IDC at 12-o'clock position (arrow). Lesion conspicuity score was 3, indicating better lesion visualization at breast CT.

Figure 2b:

(a) Craniocaudal screen-film mammogram of right breast shows 4-mm IDC (arrow). (b) Coronal CT scan in same woman in same breast shows 4-mm IDC at 12-o'clock position (arrow). Lesion conspicuity score was 3, indicating better lesion visualization at breast CT.

Figure 3a:

(a) Craniocaudal and (b) spot magnification screen-film mammogram of right breast shows 7-mm cluster of suspicious microcalcification lesions (arrow). (c) Transverse breast CT scan shows microcalcification lesions in ill-defined mass (DCIS) (arrow). Lesion conspicuity score was 7, indicating superior visualization at mammography.

Figure 3b:

(a) Craniocaudal and (b) spot magnification screen-film mammogram of right breast shows 7-mm cluster of suspicious microcalcification lesions (arrow). (c) Transverse breast CT scan shows microcalcification lesions in ill-defined mass (DCIS) (arrow). Lesion conspicuity score was 7, indicating superior visualization at mammography.

Figure 3c:

(a) Craniocaudal and (b) spot magnification screen-film mammogram of right breast shows 7-mm cluster of suspicious microcalcification lesions (arrow). (c) Transverse breast CT scan shows microcalcification lesions in ill-defined mass (DCIS) (arrow). Lesion conspicuity score was 7, indicating superior visualization at mammography.

Figure 4a:

(a) Craniocaudal screen-film mammogram and (b) transverse, (c) coronal, and (d) sagittal breast CT scans of left breast show a spiculated mass (IDC) (arrow) at 1-o'clock position in upper outer quadrant. Lesion conspicuity score was 5, indicating slightly better visualization at breast CT.

Figure 4b:

(a) Craniocaudal screen-film mammogram and (b) transverse, (c) coronal, and (d) sagittal breast CT scans of left breast show a spiculated mass (IDC) (arrow) at 1-o'clock position in upper outer quadrant. Lesion conspicuity score was 5, indicating slightly better visualization at breast CT.

Figure 4c:

(a) Craniocaudal screen-film mammogram and (b) transverse, (c) coronal, and (d) sagittal breast CT scans of left breast show a spiculated mass (IDC) (arrow) at 1-o'clock position in upper outer quadrant. Lesion conspicuity score was 5, indicating slightly better visualization at breast CT.

Figure 4d:

(a) Craniocaudal screen-film mammogram and (b) transverse, (c) coronal, and (d) sagittal breast CT scans of left breast show a spiculated mass (IDC) (arrow) at 1-o'clock position in upper outer quadrant. Lesion conspicuity score was 5, indicating slightly better visualization at breast CT.

Figure 5a:

(a) Craniocaudal screen-film mammogram of right breast for comparison with (b) transverse breast CT scan, which shows satellite lesion (arrow), not observed on a, adjacent to index lesion (IDC). Lesion conspicuity score was 3, indicating superior visualization at breast CT.

Figure 5b:

(a) Craniocaudal screen-film mammogram of right breast for comparison with (b) transverse breast CT scan, which shows satellite lesion (arrow), not observed on a, adjacent to index lesion (IDC). Lesion conspicuity score was 3, indicating superior visualization at breast CT.

Figure 6:

Sequential contrast-enhanced transverse breast CT scans show two enhancing, spiculated masses (arrows), both of which were IDC. Only posterior lesion (straight arrows) was seen on screen-film mammogram. The second anterior lesion (curved arrows) was not seen at mammography.