| Objective:Evaluate clinical application value of energy spectral CT MONO imaging technology united with MARS in the field of removing intracranial spring coil implant artifact.Method :(一)Collect the 2013-2015 period were selected from the Department of Neurosurgery of 15 cases of intracranial coil interventional operation of intracranial aneurysm patients(after confirmed by DSA) and review the patient imaging data, after 1 week, six months of energy spectrum(GSI) CT scan data, 1 group of 120 kVp mixed energy(QC) image, 40keV~140keV to 10 KeV intervals from group a total of 11 single energy(mono) image and 11 group MONO+MARS image. Images of each group were randomly selected and the most serious one artifact and a no artifacts in the region of interest(ROI region of interest(ROI) is used to measure the respective SD(different ROI single energy CT value variance value, remember to SD), calculated from the respective index of artifact(artifact index, AI), the SD value was analyzed by paired t test and of each image were subjective score(0-3).(二)Retrospective analysis method(一) in 15 cases of intracranial coil intervention patients with imaging data. Male 8 cases, female 7 cases, age 31 ~ 69 years average(52.3 + 3.1) years. Hunt-hess grade I- III grade 9 cases, 6 cases of grade. All the patients underwent gemstone spectral CT(GSI) scan(CT750 HD scanner, GE-Healthcare, USA). Evaluation MONO+MARS images and CT sense within the region of interest of 2-3mm coil image quality. Comparing the two images of the mean standard deviation.Results:(一)120 KVP QC images, 40 keV- 140 keV, 11 groups of MONO images and 11 groups of images about MONO united with MARs, within the scope of the 60 keV-140 keV, AI value of MONO united with MARs image is below that of MONO image, MONO image is below QC images; AI value of MONO image and MONO united with MARs image reach a lowest point in 70 keV, and begin to flatten in the following; In the SD value matching t test of QC image and MONO image with MONO image and MONO united with MARs image, in the scope of 60 keV- 140 keV, there is no significant difference between MONO image and QC image(P > 0.05), there is no significant difference between MONO united with MARs image and QC in 50 keV(P = 0.985 > 0.05), but there is significant difference in 60 keV- 140 keV and SD mean value is less than QC mean values, namely in MONO united with MARs image, noise of image in 60 keV- 140 keV group is obviously lower than other groups; In subjective evaluation, the scope of 70keV-90 keV in MONO united with MARs image obtains(2.85 ± 0.15),(2.78 ± 0.18) and(2.75 ± 0.20) respectively in the energy scope of 70 keV- 90 keV, which are far higher than other groups.(二)The average standard deviation of each MONO +MARS image in region-of-interest is significantly less than 120 kVp images and the average standard deviation(P < 0.001) of ordinary CT images. There’s no significant difference in the average standard deviation between 120 KVP images and ordinary CT images. In MONO +MARS images and ordinary CT images, the average SD decreases as keV increases, and there is no significant difference between two kinds of image change trend. In angiography, there are significant differences between the MONO+MARS images and ordinary CT images. The contrast of each MONO < 70 keV is observably superior to that of MONO > 80 keV(P < 0.05). Although there is no significant difference between the 70 keV and 80 keV(P = 0.432), the contrast of 70 keV vascular is better than > 80 keV. There is no significant difference between 70 kev and 40 ~ 70 kev(P = 0.089). In addition, the energy level of each MONO image is ignored. As for the effect of eliminating metal artifacts, MONO +MARS images is better than ordinary CT images(P < 0.05). The average score of MONO +MARS images of all patients is 2.60, and the average score of ordinary CT images is 1.00. In 15 cases of patients, there are 8 cases of MONO + MARS image with excellent visibility and no obvious metal artifacts. Three patients’ MONO +MARS images show a good degree of differentiation between the blood vessels and small metal artifacts.Conclusion:(一)In Spectral CT, MONO imaging technology united with MARs can significantly reduce intracranial spring coil implant artifact; MONO united with MARs has the most significant effect on removing intracranial spring coil implant artifact within the scope of 70 keV- 90 keV, and best energy image for clinical application is obtained in 70 keV; MONO imaging technology united with MARs in Spectral CT can significantly reduce intracranial spring coil implant artifact, which possesses with broad clinical application value.(二)It Can truthfully reflect the metal values into the surrounding structures of the CT value, and proportional to the distance, the farther the distance, the more truly reflect the organization of the CT value; energy spectrum CT mono imaging combined with the Mars technique can significantly reduced intracranial metallic implants artifacts effect, provides technical support for follow-up after intracranial coil embolization and re examination, has wide clinical application value.(三).MONO imaging technology united with MARs technology to restore the image and CT image contrast analysis, mean value and SD value decreases with the increase of keV; the average standard deviation was significantly less than that of using Mars technique to reconstruct the images alone, and recombinant technology under the visual effect of image better. |
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