Abstract
The purpose of this study was to evaluate using lesion washout (WO) volume fraction as a biomarker to improve the characterization of suspicious breast lesions. Study lesions consisted of a total of 60 malignant tumors (BI‐RADS 6) and 62 suspicious lesions (BI‐RADS 4 or 5). The biopsies of these suspicious lesions resulted in a total of 30 malignant tumors and 32 benign lesions, respectively, yielding a 48.4% positive predictive value (PPV) of the biopsies. The mean and standard deviation of the lesion WO volume fraction of these 60 BI‐RADS 6 malignant tumors were first computed to establish a 99% sensitivity threshold value for malignant tumors, and then the biomarker was used to characterize the suspicious lesions. Using the biomarker would characterize all the malignant tumors as malignant, 12 out of the 32 benign lesions as benign, potentially resulting in a 24% improvement rate in the PPV of the biopsies (from 48.4% to 60%) and consequently a 22.5% reduction rate in the false‐positive rate of benign biopsies (from 51.6% to 40%). The lesion WO volume fraction biomarker could improve the computer‐based assessment of breast MRI by increasing the PPV of breast biopsies and reducing the number of unnecessary biopsies without compromising sensitivity.PACS number: 87.61.Tg, 87.19.Xj
Highlights
Breast dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) demonstrates high sensitivity for malignant breast tumor detection, but the specificity is relatively low, resulting in many false-positive diagnoses of suspicious lesions (BI-RADS assessment of 4 or 5) in clinical practice, and produces a relatively low positive predictive value (PPV) for biopsies.(1-6) In a recent study involving a total of 125 suspicious breast lesions, the breast biopsies resulted in 42 malignant tumors and 83 benign lesions, showing a 33.6% PPV of the biopsies and, a 66.4% false-positive rate of benign biopsies at the clinic.[7]
The WO curve mainly reflects the hypervascularity associated with tumor angiogenesis essential for tumor growth.[8,9,10] most benign lesions exhibit a slower, but persistent, enhancement (PE) without the WO behavior, suspicious enhancement curves in some areas showing WO behavior are frequently observed in many benign lesions including fibroadenomas and proliferative fibrocystic changes.[1,4] These suspicious enhancement curves are mainly responsible for many false-positive diagnoses of suspicious breast lesions in clinical practice
Kinetic features of the postcontrast signal intensity time courses correlate with microvessel density; the WO curve has the highest microvessel density, followed by the plateau curve and the PE curve with the lowest microvessel density.[8]. The areas of greatest enhancement in malignant tumors show a typical WO curve and correlate with microvessel density.[9]. These findings imply that the WO curve may reflect the hypervascularity associated with tumor angiogenesis and, the lesion WO volume fraction, characterized as the ratio of the total volume of the WO voxels that demonstrate the WO curve within the tumor to the whole tumor volume, may provide a measure to quantify the hypervascularity of the tumor
Summary
Breast dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) demonstrates high sensitivity for malignant breast tumor detection, but the specificity is relatively low, resulting in many false-positive diagnoses of suspicious lesions (BI-RADS assessment of 4 or 5) in clinical practice, and produces a relatively low positive predictive value (PPV) for biopsies (the number of cancers detected divided by the number of biopsies performed).(1-6) In a recent study involving a total of 125 suspicious breast lesions, the breast biopsies resulted in 42 malignant tumors and 83 benign lesions, showing a 33.6% PPV of the biopsies and, a 66.4% false-positive rate of benign biopsies (the ratio of biopsied benign lesions to the number of biopsies performed) at the clinic.[7] Most malignant tumors demonstrate an initial enhancement followed by a rapid washout (WO) or plateau curve in the postcontrast signal intensity time courses. This study, with a more than four times larger sample size, further tests the potential of using this biomarker to improve the characterization of suspicious breast lesions
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