Subtraction CT angiography in head and neck with low radiation and contrast dose dual-energy Spectral CT using rapid kV-switching technique.

Subtraction CT angiography in head and neck with low radiation and contrast dose dual-energy Spectral CT using rapid kV-switching technique.

Br J Radiol. 2018 Feb 07;:20170631

Authors: Ma G, Yu Y, Duan H, Dou Y, Jia Y, Zhang X, Yang C, Chen X, Han D, Guo C, He T

Abstract
OBJECTIVE: To investigate the application of low radiation and contrast dose Spectral CT angiology (CTA) using rapid kV-switching technique in the head and neck with subtraction method for bone removal.
METHODS: This prospective study was approved by the local ethics committee. 64 cases for head and neck CTA were randomly divided into groups A (n=32) and B (n=32). Group A underwent unenhanced CT with 100kVp, 200mA and contrast-enhanced CT with Spectral CT mode with BMI-dependent low dose protocols. Group B used conventional helical scanning with 120kVp, auto mA for noise index of 12HU for both the unenhanced and contrast-enhanced CT. Subtraction images were formed by subtracting the unenhanced images from enhanced images (with the 65keV enhanced Spectral CT image in group A). CT numbers and their standard deviations (SD) in aortic arch, carotid arteries, middle cerebral artery and air were measured in the subtraction images. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for the common and internal carotid arteries and middle cerebral artery were calculated. Image quality in terms of bone removal effect was evaluated by two experienced radiologists independently and blindly using a 4-point system. Radiation dose and total iodine load were recorded. Measurements were statistically compared between the two groups.
RESULTS: The two groups had same demographic results. There was no difference in the CT number, SNR and CNR values for carotid arteries and middle cerebral artery in the subtraction images between the two groups (p>0.05). However, the bone removal effect score (median (min-max)) in group A (4 (3-4)) was rated better than in group B (3 (2-4)) (p<0.001), with excellent agreement between the two observers (Kappa>0.80). The radiation dose in group A (average of 2.64mSv) was 57% lower than the 6.18 mSv in group B (p<0.001). The total iodine intake in group A was 13.5g, 36% lower than the 21g in group B.
CONCLUSION: Spectral CT imaging with rapid kV-switching in the Subtraction angiography in head and neck provides better bone removal with significantly reduced radiation and contrast dose compared with conventional subtraction method. Advances in knowledge: This novel method provides better bone removal with significant radiation and contrast dose reduction compared with the conventional subtraction CT, and maybe used clinically to protect the thyroid gland and ocular lenses from unnecessary high radiation.

PMID: 29412008 [PubMed - as supplied by publisher]

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