Li-mei Pei,Gao-feng Shi＊,Run-ze Wu,Ru-xun Li,and Yu Du

CT Room,Hebei Medical University Fourth Hospital,Shijiazhuang 050011,China

GASTRIC cancer is one of the most frequently diagnosed cancers and leading causes of cancer-related deaths.Computed tomography (CT)is routinely used to observe the tumor location,size,invasion,and metastasis,which are necessary for tumor staging and therefore treatment planning.With the recently introduced dual-source dual-energy CT (DECT),different kevS images could be obtained,the feature of which depending on the attenuation coefficient of the scanned tissue.We investigated spectrum characteristics of the curve of normal gastric tissue and those with gastric cancer,normal fat and invased fat,metastatic lymph nodes in DECT.

Forty patients were consecutively enrolled from December 2010 to May 2011,including 35 males and 5 females at the age of 60.2±8.5 years (range,29-74 years).The diagnosis of gastric cancer in these patients was confirmed by endoscopic biopsy.After the DECT examination,the patients received surgery within 1 week.Postoperative pathological examination revealed infiltration into adjacent fat tissue and metastasis in lymph nodes in all the cases.After at least 6 hours of fasting,DECT was performed with tube voltage of 100/Sn140 kVp.Scopolamine butylbromide(10 mg) was administered,and 800 mL water orally taken before scanning.The DECT images were sent to a workstation for spectral analysis.A round region-of-interest(ROI) was placed on the normal gastric wall,tumor,normal fat,infiltrated fat,and metastatic lymph node,respectively.The CT values were obtained to draw the spectrum curves of these tissues.

Energy spectrum of the normal stomach and gastric cancer areas showed a slightly downward trend in the curve with different gradients.The CT values of normal gastric wall were higher than those of gastric cancer in 40-80 Kev.In 90-190 Kev,no significant difference was found between the normal gastric wall and gastric cancer.Spectrum curve of the normal fat at 40-100 Kev showed a upward trend.The curve of infiltrated fat was flat,and the CT values higher than those of normal fat.The CT values of gastric cancer and metastatic lymph node tended to decrease,most significant in 40-80 Kev.In 80-190 Kev,the two curves were flat and roughly parallel.

Unlik the ordinary single-energy CT,DECT had a high sensitivity of the chemical composition of different tissues.Investigation of the characteristics of different tissues is allowed by analysis of their spectral spectrum.In this study,the spectrum curves of normal gastric wall,gastric cancer,normal fat,infiltrated fat,and metastatic lymph node showed different characteristics,providing useful clinical information.Therefore spectrum curves generated with DECT may help to identify gastric cancer,invasion into surrounding fat tissue,and lymph node metastasis.