FDG SUVmax and DWI ADC for predicting the biological aggressiveness of breast cancers

Objectives To evaluate the usefulness of FDG maximum standardized uptake values (SUVmaxs) and apparent diffusion coefficients (ADCs) for predicting the biological aggressiveness of breast cancer before therapy.

Methods Thirty three female patients with breast cancers underwent both FDG-PET/CT and 1.5T MRI diffusion-weighted imaging (DWI) before therapy. Both SUVmaxs and ADCs of breast cancers were calculated. The pathological diagnosis consisted of invasive ductal carcinoma (IDC, n=27) and non-invasive ductal carcinoma (NIDC, n=6). The histological grades of IDC were grade 1 (n=3), grade 2 (n=14) and grade 3 (n=10). Both SUVmax and ADC (b =1000) were statistically compared between IDC and NIDC, and among the histological grades in IDC.

Results Thirty of 33 cancers were visible on both FDG-PET and DWI. The 3 invisible cancers were all less than 5mm in diameter. In 30 visible cancers, significant differences were observed in the SUVmax between IDC (6.8±5.0) and NIDC (2.6±1.2) (P=0.023) and in ADC (x10^-3mm²/s) between IDC (0.91±0.15) and NIDC (1.06±0.15) (P=0.028). The threshold levels of 2.0 for SUVmax and 1.11 for ADC yielded the same diagnostic values for diagnosing IDC; sensitivity 92% (22/24), specificity 67% (4/6), PPV 92% (22/24), NPV 67% (4/6) and accuracy 87%(26/30). There were also significant differences in SUVmax (grade 1:1.4±0.6, grade 2: 5.9±4.1, grade 3: 9.3±5.3, P=0.008) and in ADC (grade 1: 1.10±0.09, grade 2: 0.98±0.10, grade 3: 0.77±0.06, P<0.001) among 3 grades.

Conclusions These results suggest that both FDG SUVmax and DWI ADC can predict the biological aggressiveness of breast cancers.