The lesion only 4 mm. in size. But located in a typical location in posterior aspect of the upper pole of left lobe of thyroid.
Markedly vascular lesions in this location are usually parathyroid adenomas. The gray scale ultrasound image suggests a solid lesion, thus suggestive of an adenoma of the parathyroid gland.
Such a highly vascular lesion can also suggest a possibility of an Arterio-venous malformation of the thyroid or the parathyroid. This is where this color Doppler ultrasound video might help (see below): this video shows a transverse section through the left lobe.
This color Doppler video clip below shows a long section of the left lobe of thyroid. The lesion is seen posteriorly.
See: http://www.ultrasound-images.com/thyroid.htm for more.
Specifically about parathyroid adenomas- visit: