|Author||Year||Number of cases and histologic subtype||Size range||Prognostic measure||Sonographic parameters studied||Selected results|
|Cappelli et al. ||2007||484 PTC||<1.0 cm to > 4.0 cm||Recurrence of disease or death due to thyroidcancer||Blurred margins, presence of calcifications, intranodular vascularity, hypoechogenicity, multifocality, extracapsular growth||Among investigated sonographic parameters, only intranodular flow associated with unfavorable outcome|
|Du et al. ||2015||
|N/A||LN mets||Size, peak systolic velocity, pulsatility index, resistive index, multifocality, bilateral vs. unilateral, nodule border, edge irregularity, halo, solid/cystic vs. solid, uniformity of echogenicity, echogenicity, microcalcifications, flow grade, capsular invasion||
Large size, percent contact with thyroid capsule, microcalcifications, flow grade 3–4 (graded from 0–4), resistive index >0.654, peak systolic velocity > 24.5 cm/s associated with LN mets.|
Additional categories not associated with LN mets.
|Fukuoka et al. ||2015||480 PTC in 384 patients||<1.0 cm||Increase in tumor size ≥3 mm (prospective trial)||Calcification pattern, tumor vascularity||Macroscopic/rim calcifications and poor vascularity on most recent follow-up associated with non-progression of disease. These features were also strongly associated with advanced age.|
|Gweon et al. ||2016||397 PTC||3–35 mm||
|Tumor composition, echogenicity, margins, calcifications, shape, TI-RADS category (Kwon classification), size||
Size associated with ETE.|
Size, microcalcifications associated with LN mets.
All additional categories not associated with ETE or LN mets
|Kamaya et al. ||2015||62 PTC||>1.0 cm||ETE||Capsular abutment, contour bulging, vascularity beyond capsule, loss of echogenic capsule||
Capsular abutment 100% sensitive for extracapsular extension|
Loss of echogenic capsule was best predictor of ETE.
|Kim et al. ||2011||354 PTC||≤2 cm||
|Size, shape, margin, echogenicity, calcification, vascularity, contact with capsule||
Size >0.5 cm, marked hypoechogenicity, contact with capsule associated with ETE.|
Marked hypoechogenicity associated with LN mets.
Additional factors were not predictive.
|Lai et al. ||2016||367 PTC||≤1.0 cm||
|Size, shape, length/width ratio, border, peripheral halo, echogenicity, cystic change, calcification (any), vascularity, presence of Hashimoto’s thyroiditis||
Size associated with LN mets and ETE.|
Calcification (any), multifocality associated with LN mets only for microcarcinoma > 5 mm.
Additional features were not associated with LN mets; no US features associated with LN mets for microcarcinoma < 5 mm.
|Lee et al. ||2014||568 PTC||3–49 mm||ETE||Size, lesion location, echogenicity, (LN stage), % abutment of thyroid capsule, capsular protrusion||Size, thyroid capsular protrusion, % abutment of thyroid capsule are all associated with ETE.|
|Zhan et al. ||2012||155 PTC||<10 mm to greater than 40 mm||LN mets||Size, shape, border, margin, halo, internal architecture, echogenicity, homogeneity of echotexture, calcification, contact between nodule border and thyroid, vascularity, peak systolic velocity, pulsatility index, resistive index||
Size, contact percentage, combined microcalcifications/ macrocalcifications, increased vascularity, high resistive index difference associated with LN mets.|
No association seen with other parameters.