The role of diffusion-weighted and dynamic contrast enhancement perfusion-weighted imaging in the evaluation of salivary glands neoplasms.

Objectives: To evaluate the association of magnetic resonance diffusion-weighted imaging (DwI) and dynamic contrast-enhanced perfusion-weighted imaging (DCE-PwI) with a temporal resolution of 5 s, wash-in < 120 s, and wash-out ratio > 30% in the evaluation of salivary glands neoplasms.
Methods: DwI and DCE-PwI of 92 salivary glands neoplasms were assessed. The apparent diffusion coefficient (ADC) was calculated by drawing three regions of interest with an average area of 0.30-0.40 cm ² on three contiguous axial sections. The time/intensity curve was generated from DCE-PwI images by drawing a region of interest that included at least 50% of the largest lesion section. Vessels, calcifications, and necrotic/haemorrhagic or cystic areas within solid components were excluded. The association of ADC ≥ 1.4 × 10 ^-3  mm ² /s with type A curves (progressive wash-in) and ADC 0.9-1.4 × 10 ^-3  mm ² /s with type C curves (rapid wash-in/slow wash-out) were tested as parameters of benignity and malignancy, respectively. Type B curve (rapid wash-in/rapid wash-out) was not used as a reference parameter.
Results: ADC ≥ 1.4 × 10 ^-3  mm ² /s and type A curves were observed only in benign neoplasms. ADC of 0.9-1.4 × 10 ^-3  mm ² /s and type C curves association showed specificity of 94.9% and positive predictive value of 81.8% for epithelial malignancies. The association of ADC < 0.9 × 10 ^-3  mm ² /s with type B and C curves showed diagnostic accuracy of 94.6% and 100% for Warthin tumour and lymphoma, respectively.
Conclusions: ADC ≥ 1.4 × 10 ^-3  mm ² /s and type A curves association was indicative of benignity. Lymphomas exhibited ADC < 0.7 × 10 ^-3  mm ² /s and type C curves. The association of ADC < 0.9 × 10 ^-3  mm ² /s and type B and C curves had accuracy 94.6% and 88.5% for Warthin tumour and epithelial malignancies, respectively.