Using lesion washout volume fraction as a biomarker to improve suspicious breast lesion characterization

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

Quality assurance of four-dimensional computed tomography in a multicentre trial of stereotactic body radiotherapy of centrally located lung tumours

“…Amplitude deviations were calculated and analysed for each 4DCT acquisition separately. Thereafter, it was investigated whether there was a correlation between the cranio-caudal amplitude deviations and the pitch value used, as studies have shown that an inaccurate longitudinal position of the target volume as seen in some 4DCT images might be caused by an inadequate sampling related to the combination of pitch used, breathing frequency of the patient and scanner rotation speed [14] . In 4DCT imaging the helical pitch is defined as the table distance travelled in one rotation divided by the total collimated width of the X-ray beam at isocentre.…”

“…For multi-slice CT’s the effective imaging plane is variable across the FOV. The maximum pitch at the isocentre plane can be expressed as follow [14] : where p max = maximum pitch, t rot = rotation time in seconds, Tb = breathing period in s, FOV = reconstructed Field Of View, R = Focus to isocentre distance…”