Color Doppler (CD) imaging has enabled identification of flow in
thyroid tumors, but its role in evaluation of thyroid nodules for malignancy
has not been accurately defined. CD and spectral parameters were analyzed in 50 benign
and 20 malignant thyroid nodules. Following patterns of vascularity were identified: pattern 0 – no visible flow; pattern
1 – minimal internal flow without a peripheral ring; pattern 2 – peripheral ring of flow but minimal or no internal
flow; pattern 3 – peripheral ring of
flow and a small-to moderate amount of internal flow; pattern 4 – extensive internal flow with or without a peripheral
ring. Peak systolic velocities (PSV) and end diastolic velocities (EDV) were
measured and resistance index (RI) was calculated. Significantly more benign
nodules had vascularization patterns 1,2 and 3 (χ2-test; χ2=32,106,
p<0,0001). Significantly more malignant nodules had vascularization patterns
3 and 4 (χ2-test; χ2=16,978, p<0,0001), and only
pattern 4 (χ2-test; χ2=32,106, p<0,0001). EDV was
significantly (Kruskal-Wallis test; H=15,0595, p<0,0001) lower in malignant
nodules then in benign (6,06±4 cm/s vs
13,01±8,74 cm/s). RI was significantly higher (Kruskal-Wallis test; H=34,3776,
p<0,0001) in malignant then benign thyroid nodules (0,75±0,08 vs 0,56±0,09). For RI ≥ 0,70; 80%
sensitivity, 92% specificity, 80% positive predictive value, 92% negative
predictive value, and 88,6% accuracy, was calculated in characterizing
malignant thyroid nodules. We believe that internal flow without or minimal
peripheral flow on CD and RI≥0,70 can be used to relatively reliably
distinguish malignant and benign thyroid nodules. Nodules with prevailing
peripheral vascularization and minimal or no internal vascularization, and RI
below 0,70 are probably benign.
