Assessing parotid gland tumor perfusion with a new imaging biomarker DDVD (diffusion-derived vessel density): promising initial results.

Abstract

DDVD (diffusion-derived vessel density) is an MRI surrogate of the area of micro-vessels per unit tissue area. DDVD is calculated according to: DDVD(b0b20) = Sb0/ROIarea0 - Sb20/ROIarea20, where Sb0 and Sb20 refer to the tissue signal when b is 0 or 20 s/mm². This study applied DDVD to assess the perfusion of parotid gland tumors.MRI was performed at 3.0T. Diffusion-weighted images with b-values of 0, 20, 1000 s/mm² were acquired for 24 pleomorphic adenomas (PA), 16 Warthin's tumors (WT), and 14 malignant tumors (MT). DDVDr was DDVD of the tumor divided by DDVD of tumor-free parotid gland tissue. A systematic literature search was conducted for parotid gland tumor perfusion imaging studies. Perfusion parameters of PA, MT, and WT were normalized by PA value, and thus the ratio for PA value was assumed to be 1. The ratio results of MT DDVDr and WT DDVDr further normalized by PA DDVDr were compared with the literature results. In addition, the ADC (apparent diffusion coefficient) was calculated with b=0, 1000 s/mm² images.Most of the tumors were hyper-vascular relative to native parotid gland tissue with DDVDr >1, with PA, MT, and WT having mean DDVDr values of 1.753±0.462, 2.731±2.254, and 4.324 ±3.203, respectively. DDVDr ratios of MT/PA and WT/PA agreed with the literature perfusion results derived with non-DWI methods, particularly consistent with CT perfusion blood volume results. PA, MT, and WT had ADC values of 1.485 ±0.36, 0.969± 0.194, and 0.772± 0.070 (×10^-3 mm²/s), respectively. WT had very high DDVDr and low ADC, while PA had moderately high DDVDr and very high ADC. Most of the MTs had moderately high DDVDr and low ADC. A combination of ADC and DDVDr can largely differentiate between PA and WT.DDVD results approximately agree with parotid gland perfusion imaging literature data. A combination of DDVD and ADC may support parotid gland tumor tissue characterization. · As a straightforward diffusion MRI biomarker, DDVD can be used to assess parotid gland tumor perfusion.. · Warthin's tumors have very high DDVD and low ADC.. · Pleomorphic adenomas have moderately high DDVDr and very high ADC.. · A combination of ADC and DDVDr can largely differentiate between pleomorphic adenoma and Warthin's tumor.. · Yao D, King AD, Zhang R etal. Assessing parotid gland tumor perfusion with a new imaging biomarker DDVD (diffusion-derived vessel density): promising initial results. Rofo 2024; DOI 10.1055/a-2543-3305.