Spectral CT imaging of intranodular hemorrhage in cases with challenging benign thyroid nodules.

While conventional ultrasound and laboratory testing can differentiate most thyroid conditions and malignancies, spectral dual-energy computed tomography (DECT) provides molecular data potentially useful in differential diagnosis of small, complex, and partially obscured hemorrhaged nodules with recent bleeding. To demonstrate that Gemstone Spectral Imaging (GSI) analysis of DECT data differentiates challenging benign thyroid nodule conditions in patients with intranodular hemorrhages. A retrospective study was conducted of 30 intranodular hemorrhage patients from 2010 to 2013, including 18 that underwent surgery and provided thyroid tissues for prospective histological analysis. Iodine and water content were determined in patient CT scans and ex vivo tissue specimen scans by reconstruction of raw CT data at 65 keV (optimal contrast). Slope of spectral curve (λ HU), effective atomic number (Z eff), and final pathological diagnosis were recorded. Iodine content, water content, Z eff, and λ HU significantly varied by region (intranodular hemorrhage, solid thyroid nodule, and adjacent margins) in patients and tissue specimens (P < 0.05). Intranodular hemorrhage exhibited elevated water concentrations (~1100 mg/mL), suggesting a practical threshold of 1075 mg/mL for differentiating intra-plaque hemorrhage and solid nodular regions. Spectral CT provided diagnostic information in 14 thyroid adenomas and four goiters (histologically confirmed in donor specimens), and eight thyroid adenomas and four nodular goiters based on clinical diagnosis. Diagnostically useful regional characteristic of intranodular hemorrhage in the thyroid was visualized via spectral CT employing material decomposition, potentially yielding additional molecular data about complex lesion characteristics no apparent in conventional imaging or laboratory methods.