Comparison of Standard and Quadruple-Phase Contrast Material Injection for Artifacts, Image Quality, and Radiation Dose in the Evaluation of Head and Neck Cancer Metastases

Purpose: To investigate opacification of head and neck vasculature during computed tomography (CT) of supraclavicular lymph nodes with a quadruple-phase contrast media and saline dual-injection protocol. Materials and Methods: This retrospective study was institutional review board approved. In 180 consecutive patients, routine head and neck CT was performed with one of two protocols: protocol A, craniocaudal scan direction with 100 mL of contrast material injected intravenously as a single bolus; or protocol B, 100 mL of contrast material injected in four phases (phases 1-2, 60 mL of contrast material and saline injected at 2.5 mL/sec; phases 3-4, 40 mL of contrast material and saline injected at 2.5 mL/sec); both protocols had a fixed scan delay of 70 seconds. Attenuation of supraclavicular arteries and veins was measured with arteriovenous contrast ratio (AVCR) and contrast-to-noise ratio (CNR). Effective dose was calculated. Data were compared with the two-sample t test. Receiver operating characteristic (ROC) and visual grading characteristic analyses were performed. Results: Arterial attenuation was up to 20% higher (P < .05) after protocol B (mean +/- standard deviation, 234.5 HU +/- 33.2) than protocol A (160.0 HU +/- 29.5). Venous system attenuation was significantly lower in protocol B (164.0 HU +/- 17.0) than in protocol A (664.0 HU +/- 12.0), with up to a 75% reduction (P < .0001). Protocol B generated significant (P < .0001) improvements in AVCR at multiple anatomic sites. At all anatomic levels, mean CNR with protocol B (34.4 HU +/- 9.0) was significantly higher than that with protocol A (14.5 HU +/- 14.0) (P < .0313). Effective dose was significantly reduced with protocol B (2.6 mSv +/- 0.4 vs 3.2 mSv +/- 0.8 with protocol A; P < .0041). ROC analysis demonstrated significantly higher area under the ROC curve for protocol B (P < .0022), with interreader agreement increasing from poor to excellent in lymph node visualization. Conclusion: Significant improvement in lymph node visualization at the cervicothoracic junction is achieved with a quadrupl-phase contrast media injection protocol. (C) RSNA, 2015.