Dedicated contrast-enhanced (CE) breast CT delivered significantly improved conspicuity of malignant breast lesions, including ductal carcinoma in situ (DCIS), compared with unenhanced breast CT and mammography, according to a study published in the September issue of Radiology.
Although preliminary, the study is a harbinger of good things to come, said senior author John M. Boone, PhD, professor of research, radiology at University of California Davis Medical Center in Sacramento, in an interview.
The Boone Laboratory at University of California Davis Medical Center studies the potential of breast CT using a custom-designed breast CT scanner that produces 300 to 500 tomographic slices of the breast at a radiation dose comparable to mammography.
In initial clinical studies, the prototype performed on par with mammography in distinguishing benign and malignant lesions. Although CT provided superior visualization of masses, mammography offered better visualization of microcalcifications. The ultimate utility of the modality hinges on its improving its sensitivity and specificity over mammography, especially for DCIS, according to the study, which was led by Nicolas D. Prionas, MS.
The researchers undertook the study to quantify contrast material enhancement of breast lesions scanned with the prototype and compare lesion conspicuity with unenhanced breast CT and mammography.
The research team recruited 46 women (mean age, 53.2 years) with BI-RADS category 4 or 5 lesions to undergo unenhanced and CE breast CT between September 2006 and April 2009. Two radiologists independently scored the studies for lesion conspicuity versus mammography and unenhanced breast CT. Researchers also completed quantitative image analysis in 52 lesions, segmenting each lesion from the pre- and post-contrast images and calculating descriptive statistics for the volume of interest.
Malignant lesions and benign lesions were significantly more conspicuous at CE breast CT than at mammography (P ‹ .001 and P = .0003, respectively), which could improve the specificity of CE breast CT, reported the authors.
"With the addition of contrast, microcalcifications lit up and benign microcalcifications showed significantly reduced contrast uptake," explained Boone, which indicates potential for good specificity and also may offer data to help physicians predict malignant potential prior to biopsy.
Conspicuity of malignant lesions identified as microcalcifications did not differ significantly between CE CT and mammography, and mammography provided significantly better visualization of benign calcifications.
Regression models comparing CE breast CT and unenhanced breast CT confirmed that all lesion types were seen better with CE breast CT. In addition, both high- and low-density breasts had mean conspicuity scores that favored CE CT over mammography. Finally, regression models showed that malignant lesions enhance more than benign lesions on contrast-enhanced breast CT, according to the study.
“Contrast-enhanced breast CT offers a promising quantitative technique with which to predict malignancy in breast tumors,” wrote the authors. In addition, it may offer a viable alternative to dynamic contrast-enhanced MR imaging.
If the prototype is commercialized, breast CT could provide an option for claustrophobic women and patients with metal implants. In addition, CE breast CT could prove useful in the biopsy setting. However, future studies are needed to determine whether bilateral CE breast CT is necessary to increase the specificity of the modality, as in MR imaging, concluded the authors.