Advanced Modeled Iterative Reconstruction in Low Tube Voltage Contrast Enhanced Neck CT: Evaluation of Objective and Subjective Image Quality
BACKGROUND AND PURPOSE: Dose saving techniques in neck CT cause increased image noise that can be counteracted by iterative reconstruction. Our aim was to evaluate the image quality of advanced modeled iterative reconstruction (ADMIRE) in contrast enhanced low tube voltage neck CT. MATERIALS AND METHODS: Sixty one patients underwent 90 kV(peak) neck CT by using third generation 192 section dual source CT. Image series were reconstructed with standard filtered back projection and ADMIRE strength levels 1, 3, and 5. Attenuation and noise of the sternocleidomastoid muscle, internal jugular vein, submandibular gland, tongue, subscapularis muscle, and cervical fat were measured. Signal to noise and contrast to noise ratios were calculated. Two radiologists assessed image noise, image contrast, delineation of smaller structures, and overall diagnostic acceptability. Interobserver agreement was calculated. RESULTS: Image noise was significantly reduced by using ADMIRE compared with filtered back projection with the lowest noise observed in ADMIRE 5 (filtered back projection, 9.4 2.4 Hounsfield units [HU] ADMIRE 1, 8.3 2.8 HU; ADMIRE 3, 6.7 2.0 HU; ADMIRE 5, 5.4 1.7 HU; all, P .001) Sternocleidomastoid SNR and internal jugular vein sternocleidomastoid contrast to noise ratios were significantly higher for ADMIRE with the best results in ADMIRE 5 (all, P .001) Subjective image quality and image contrast of ADMIRE 3 and 5 were consistently rated better than those for filtered back projection and ADMIRE 1 (all, P .001) Image noise was rated highest for ADMIRE 5 (all, P .005) Delineation of smaller structures was voted higher in all ADMIRE strength levels compared with filtered back projection (P .001) Global interobserver agreement was good (0.75) CONCLUSIONS: Contrast enhanced 90 kVp neck CT is feasible, and ADMIRE 5 shows superior objective image quality compared with filtered back projection. ADMIRE 3 and 5 show the best subjective image quality.
American Journal of Neuroradiology