Echo Doppler in the characterization of thyroid nodular disease

: This study was aimed at investigating role and efficacy of color-Doppler US in the characterization of thyroid nodules. Eight-three consecutive patients with only one solid thyroid nodule, not smaller than 0.8 cm, were examined. They were submitted to scintigraphy and laboratory tests first and then to color-Doppler US, to fine-needle biopsy and/or to histologic examinations. Color-Doppler US examinations were performed with a 7.5 MHZ linear probe, 5-MHz Doppler frequency, PRF = 0.8 KHz, 40-50 degrees insonation angle, wall filters at the lowest level, 2-5 mm sample volume, color and Doppler gains set at 30-50% and asynchronous data collection. The final diagnosis, made at cytology and/or histology, showed 43 follicular hyperplasias, 19 follicular adenomas and 21 carcinomas. The following US variables were considered: nodule size, site, margins and the possible presence of the "halo sign" pattern, with a special attention paid to micro-/macrocalcifications, signs of invasion of surrounding anatomic structures and possible adenopathies. With color-Doppler US, we studied presence and distribution of nodular vascularization, peak (Vp) and middle (Vm) velocity, resistive index (RI) and Doppler spectrum morphology. In agreement with the current literature, 3 patterns of nodular vascularization were considered: not apparent, or type I (3/83), which was found only in follicular hyperplasia; peripheral, or type II (46/83) and finally, peri- and intranodular, or type III (31/83). Hyperplasias exhibited a type I pattern rarely and exclusively and, if vascularized, they always exhibited Vp 50 cm/s and mostly (18/19) RI 0.75, while if Vp < 50 cm/s, their RI was independent of the threshold value of 0.75. These preliminary conclusions seem to confirm that vascular patterns alone are not particularly helpful, compared with B-mode US results, in distinguishing among thyroid nodules. Nevertheless, Vp and RI may be of great usefulness in the characterization of solid nodules and in the selection of the patients to submit to fine-needle biopsy.