Objective To evaluate the value of gemstone spectral imaging (GSI)and multi artifact reduction system(MARs)in re-ducing metallic implants artifacts,and find the best monochromatic images.Methods Twenty-one patients with metal implants in our hospital receievd GSI examination ,MARS reconstruction and polychromatic images(140 kVp).Eleven groups of monochromatic and MARS images were obtained from 40 keV to 140 keV every interval of 10 keV by the special GSI viewer ,respetively.Subjective image quality of two methods were assessed by 3 radiologists in consensus.For every patient one group monochromatic images and blend enery images were selected two heaviest artifacts level and no artifacts level,the CT value and the standard deviations(SD)value of the region of interest(ROI)were meatured of artifacts.Contrast-to-noise ratio(CNR)and artifacts index(AI)were also caculated and were analyzed with paired-t test.Results There was significant statistical differences of CNR between energy spectral images and blend energy images in energy level of 40 to 120 keV(P <0.05),while there was no difference in energy level of 130 to 140 keV (P >0.05),and the optimal CNR was acquired at the energy level of 70 keV(CNR=8.75±3.28).The value of AI for two mehtods has no difference in energy level scope 40 to 60 keV(P >0.05),there was significant statistical differences of AI between energy spectral images and blend energy images in energy level of 70 to 140 keV(P <0.05),and the lowest of AI(AI=26.95±9.64)was ac-quired at 1 10 keV images.Conclusion The energy spectral CT possess superiority in decreasing the artifacts and will provide high image quality in the metal implants.Gemstone spectral CT has great significance for postoperative patients with metal implants in imaging diagnosis.

Objective: To understand the status and food sources of daily dietary intake of sodium and potassium among adult inhabitants in Tianjin city, and to compare the consistence of sodium and potassium intake determined by combination of 3 consecutive 24-hour recalls and weighing family condiments (3 d dietary survey method) with 24 h urine sodium and potassium determination. Methods: Multistage cluster sampling method was applied to select 1 955 adult inhabitants from 840 households of 7 districts in Tianjin in 2015. Questionnaire survey was used to obtain basic information, 3 d dietary method was used to obtain dietary information, and 450 subjects was selected by systematic random sampling method for 24 h urine collection and determination of sodium and potassium, and 153 complete 24 h urine samples were selected by the coefficient of urinary creatinine excretion, then the consistence of the determination was compared with 3 d dietary survey method. Results: 1 828 subjects were enrolled in this study with age of (54.6±14.7) years, among which 858 were male (46.9%). The average standard intake of sodium and potassium per people per day were (5 631.2±3 372.1) mg and (1 662.1±750.5) mg, while the average actual daily intake were (5 315.8±3 196.5) mg and (1 560.7±696.8) mg. 98.7% (1 804/1 828) of the subjects had dietary sodium intake exceeding the recommended adequate intake of China residents(1 300-1 500 mg/d), while 78.5% (1 435/1 828) consumed dietary potassium below the recommended adequate intake(2 000 mg/d). The main resource of sodium was condiments, among which cooking salt accounted for 61.5%, soy sauce accounted for 11.2%. Potassium mainly came from cereals (32.4%) and vegetables (18.1%). Compared with the 24 h urine sodium method, 3 d dietary method overestimated the sodium intake with a gap [median (P₂₅, P₇₅)] as 401.7 (-1 130.6, 1 939.5) mg/d with statistical difference (P<0.05). The gap [median (P₂₅-P₇₅)] for potassium between the two methods was 79.1 (-577.5, 565.2) mg/d, without statistical difference (P>0.05). Conclusion The dietary intake of sodium is high while potassium is low among adults inhabitants in Tianjin city. Compared with the 24 h urine sodium and potassium determination, the 3 d dietary method has a good consistency in evaluating the dietary potassium intake level of the population, but overestimates the dietary sodium intake.