[An update of B-mode echography in the characterization of nodular thyroid diseases. An echographic study comparing...

We investigated B-mode US capabilities in diagnosis and characterizing thyroid nodules and compared our personal findings with those of the few analytical studies in the literature. We also compared the diagnostic accuracy of conventional 7.5 MHz versus more recent 13 MHz transducers.

We examined 136 consecutive patients with a single thyroid nodule: they were 97 women and 39 men, age ranging 15-87 years (mean: 37.4). The patients were submitted to scintigraphy and laboratory tests first and then to US, fine-needle biopsy and/or histologic examination. The final diagnosis was made at cytology and/or histology: we had 98 follicular hyperplasias, 20 follicular adenomas and 18 carcinomas. We studied the presence/absence of the halo sign, cystic portions, microcalcifications; nodule margins and echogenicity relative to the thyroid gland were also studied.

The presence of microcalcifications had the highest specificity for malignancy. The sensitivity of this parameter was higher with 13 MHz than with 7.5 MHz transducers. Relative to microcalcifications, absence of cystic portions and irregular margins, 13 MHz US had 64.7-89% accuracy. The halo sign and lesion echogenicity did not permit a reliable differential diagnosis between benign and malignant nodules with both 7.5 and 13 MHz transducers. The association of microcalcifications and irregular margins had the highest accuracy, scoring 86% at 7.5 MHz and 90.5% at 13 MHz.

High frequency US is a sensitive tool for diagnosing thyroid nodes. Accurate analysis of the US signs can suggest the benign/malignant lesion nature, which must be integrated with color, power and pulsed Doppler findings.