The Applications Of Dual Energy Scan In The Diagnosis Of Early Gastric Cancer By Dual-source CT

Part One Evaluation of the early gastric cancer using advanced image-based virtual monoenergetic plus imaging.Objective: Using novel monoenergetic algorithm monoenergetic（Mono+） evaluate the value of early gastric cancer with dual-energy CT. Search after the best display of early gastric cancer keV value.Materials and Methods: 20 patients（17men, 3women, age range 46-74, with a median age of 61.74 years） selected from March 2014 to March 2015 underwent dual-energy dual-phase scan by second-generation dual-source（100k Vp,230 m As/140 k Vp,178 m As） CT（SOMATOM Definition Flash,Siemens Healthcare,Germany）. These patients were subsequently confirmed pathologically to have early gastric cancer:either mucosal or submucasal layer invasion,and these lesions could be measured.The raw data were imported into MMWP workstation "Monoenergetic" software to get both linearly-blended 120-k V series（M₀.5） images and 40-100 keV images,post-processing software "Monoenergetic+"（IPIPE, syngo,Siemens） to get 40-100 keV images.Different keV respectively in the arterial phase of Mono and Mono+ image measuring normal stomach, CT value and the SD value lesions waist major muscle calculates lesions of CNR, SNR values. Objective image quality was compared regarding image noise, signal-to-noise ratio（SNR） and contrast-to-noise ratio（CNR） contrast. Subjective image quality was assessed by two observers.Results: In the arterial phase Mono 40 keV image noise was upper 66.76 ± 14.68, Mono+ 40 keV image noise was upper 26.55 ± 4.56, The image noise was higher in all Mono series compared to Mono+（P <0.001）. In the venous phase Mono 40 keV image noise was upper 64.78 ± 12.93, Mono+ 40 keV image noise was upper 30.53 ± 4.03, The image noise was higher in all Mono series compared to Mono+（P <0.001）.SNR: In the arterial phase, The differences in SNR showed statistical significance at 40, 50, 60 keV（P <0.05）. The no differences in SNR showed statistical significance at 70-100 keV（P >0.05）. In the venous phase,The differences in SNR showed statistical significance at 40, 50 keV（P <0.05）. The no differences in SNR showed statistical significance at 60-100 keV（P >0.05）.CNR: In the arterial phase,The differences in CNR showed statistical significance at 40, 50, 60 keV（P <0.05）. The no differences in CNR showed statistical significance at 70-100 keV（P >0.05）. In the venous phase, the differences in CNR showed statistical significance at 40, 50 keV（P <0.05）. The no differences in CNR showed statistical significance at 60-100 keV（P >0.05）.In the arterial phase M₀.5 image SNR was 4.92 ± 1.29, Mono+ 40 keV image SNR was upper 6.85 ± 2.09, Mono+ 40 keV image SNR is higher than M₀.5 image SNR（P <0.001）. In the venous phase M₀.5 image SNR was 6.61 ± 2.74, Mono+ 40 keV image SNR was upper 9.71±3.35, Mono+ 40 keV image SNR is higher than M₀.5 image（P <0.001）.In the arterial phase M₀.5 image CNR was 2.10 ± 1.54, Mono+ 40 keV image CNR was upper 3.84 ± 1.84, Mono+ 40 keV image CNR is higher than M₀.5 image CNR（P <0.001）.In the venous phase M₀.5 image CNR was 1.73±0.84, Mono+ 40 keV image CNR was upper 3.16 ± 1.34, Mono+ 40 keV image CNR is higher than M₀.5 image（P <0.001）.The readers subjectively scored image quality to be best in the 40 keV Mono+ images（P <0.001）.Conclusion: Mono+ 40 keV have greater SNR and CNR, optimum image quality, significantly reducing image noise. Mono+ 40 keV image sequence is relative to other preferred images help identify early gastric lesions and normal stomach wall.Part Two Evaluation of novel monoenergetic algorithm in dual-energy CT for T staging and screening of early gastric cancer.Objective: To evaluate a novel monoenergetic reconstruction algorithm 40 keV for dual-energy CT for T staging and screening of early gastric cancer.Materials and Methods: 51 patients（41men, 10 women, age range 36-74, mean age of 57.91±7.93 years） who underwent dual-energy dual-phase scan by Siemens second-generation dual-source CT and by pathologically confirmed patients with early gastric cancer Early gastric mucosal and submucosal layer invasion were retrospectively analyzed from May 2015 to December 2015 were selected. Check before fasting for 6-8 hours.Before CT scanning 20 min, all patients received 10 mg of butylscopolamine bromide. Two packs of gasproducing crystals（total, 6 g） were administered orally to each patient immediately prior to CT scanning to obtain gastric distention. SIEMENS SOMATOM Definition Flash scanner using the instrument.Scan mode:“A” tube voltage was 100 KVp, reference tube current 230 m As;and “B” tube voltage was 140 KVp, reference tube current 178 m As, using CARE DOSE 4D technique.After injecting contrast agents 70-140ml（1.5kg / ml, 3ml /sec, iohexol）, scaned the patient in dual- energy mode at the 30ths（arterial phase） and 70ths（venous phase）. The raw data were imported MMWP workstation "Monoenergetic" software get linearly-blended 120-k V series（M 0.5） image.And "Siemens.syngo.IPIPE" post-processing workstation "Monoenergetic+" software, get 40 keV image. Two blinded reviewers independently analyzed the CT images to assess the T stage. The results was correlated with histopathologic results. Application SPSS21.0 statistical software for statistical analysis, P<0.05 was considered statistically significant.Results: gastric cancer（32 T1a, 19T1b） were included.A total of 33 lesions were detected in M₀.5 image（18T1a, 15T1b）, T1a detection rate of 56.25%, T1 b detection rate of 78.9%, total detection rate of 64.7%. The rate of T1a and T1 b was no significant statistical difference（P=0.089）.40 keV image detected a total of 43 cases（26T1a, 17T1b）.T1a detection rate of 81.25%, T1 b detection rate of 89.5 %, total detection rate of 84.3%. The rate of T1a and T1b was no significant statistical difference（P=0.360）.Early lesions M₀.5 images and 40 keV image detection rate（P=0.023）, T1a detection rate（P=0.031） was significantly different statistically. T1 b of the detection rate（P=0.202） was no significant statistical difference.T stage: early gastric cancer T staging in M₀.5 image, the overall accuracy of 59.3%, T1a sensitivity of 66.1%, T1 b of 57.1%. T staging of early gastric cancer in 40 keV image, the overall accuracy of 69.8%, T1a sensitivity of 73.0%, T1 b of 64.7%.In M₀.5 40 keV image and the image of the overall accuracy T stage（P = 0.350）, T1a of sensitivity（P = 0.141）, and T1 b of sensitivity（P = 0.402）, there was no significant statistical difference.Conclusion: a novel monoenergetic plus 40 keV image significantly improve the gastric foci of normal stomach contrast. For early gastric cancer detection, diagnosis and T staging provides a relatively valuable results.