ObjectiveTo derive and evaluate the formula of exactly calculating the contrast dosage used during pulmonary CT angiography ( CTPA ). Methods Time density curves in 27 patients who underwent CTPA were collected and analyzed,the formula for calculating contrast dosage during CTPA was derived.68 patients suspected of pulmonary embolism ( PE ) clinically but no PE on CTPA were divided randomly into group A,with bolus tracing technique ( n =26 ),and group B,with small dose injection contrast test (SDCT) (n =42).The CT values of the right main pulmonary artery (RMPA),right upper pulmonary vein ( RUPV),right posterior basal PA,right lower PV (RLPV) and the aorta were calculated.The total contrast dosage and the hard beam artifact in the SVC were compared between the two groups.Student's t test,Chi-square test and Mann-Whitney U test were used.ResultsThe ratio of the time from starting injection to enhancement peak of caudal end of SVC and the time to enhancement peak of the main pulmonary trunk was 0.65 ±0.09 (about 2/3),the formula for contrast dosage calculation was derived as (DTs/3 + STs/2) FR ml/s.The CT values of RMPA and RLPA between the two groups[ (301 ±117),(329 ± 122) and (283 ±95),(277 ±98) HU respectively] were not significantly different (t =1.060,P =0.292 ;t =2.056,P =0.044),but the differences of CT values in the paired PA and PV between the two groups (median were 22.5,58.0 and 170.5,166.5 HU respectively ) were significant (U =292,P =0.001 and U =325,P =0.005),contrast artifact of the SVC (grade 1-3) in group B ( n =34,7,1 respectively) was significantly less than in group A (n =11,10,5 respectively,x2 =10.714,P =0.002),the contrast dosage injected in group A was ( 87.6 ± 7.3 ) ml,and in group B was ( 40.0 ±5.4) ml (P ＜0.01 ).ConclusionCTPA with SDCT technique is superior to that with conventional bolus tracing technique regarding contrast dosage and contrast artifact in the SVC.

Objective To evaluate the rules and features of the pseudoenhancement phenomenon of renal cysts during the multi-phases of contrast enhanced MSCT scan.Methods Ninety one patients with 112 simple renal cysts with B-ultrasound,CT examination,improved clinically enrolled in this retrospective study.The attenuation of the renal cysts were measured blindly in the images of CT plain scan and scans of arterial,venal and secrete phases,and the attenuation change of the cysts between pre-and post-enhanced scans were calculated; the accuracies of pseudoenhancement judging were calculated with 10 HU,15 HU and 18 HU as a threshold;the size were recorded; degree of intra renal parenchyma of the cyst were also confirmed,and so renal cysts were divided into three groups:type Ⅰ,Ⅱ and Ⅲ; The differences of attenuation among 3 enhancement phases,different size,different type were analyzed statistically with the Kruskal-wallis rank sum test,the correlation between the diameter and the pseudoenhancement in each enhancement phases were analyzed statistically with Spearman test.Results The attenuation median of the 112 cysts in plain scan,arterial,venal and secrete phase was 6.0 HU,11.0 HU,12.0 HU and 12.0 HU respectively,there was significant difference(x2=53.32,P＜0.01).The attenuation of the cysts in enhanced phases was higher than unenhanced.The range of attenuation change of the cysts between pre-and postenhanced scans was-10 to 31 HU,the number of cysts in groups of pseudoenhancement of 1 to 5 HU and 6 to 10 HU in each enhanced phase was dominant.The pseudoenhancement median of arterial,venal and secrete phase was 4.0 HU,5.0 HU and 6.0 HU respectively,There was significant difference among three groups(x2=10.062,P＜0.01).Taking 10 HU,15 HU and 18 HU as threshold for judging pseudoenhancement,the accuracy was 83.0％(239/288),95.1％(274/288) and 96.9％(279/288) respectively; Pseudoenhancement of small cysts(≤10 mm) was higher than other groups in each enhancement phase,and there was significant difference(P＜0.05).Type Ⅰ,Ⅱ and Ⅲ renal cysts were 62,23 and 27 respectively,the pseudoenhancement median of type Ⅰ renal cyst was 5.0 HU,6.0 HU and 8.0 HU respectively in arterial,venous,and excretion phase,which were higher than Type Ⅱ and Ⅲ (P＜0.05).It showed low negative correlation between pseudoenhancemen and diameter in arterial,venous and secrete phase(r =-0.326,-0.332 and-0.447,P＜ 0.01).Conclusion The pseudoenhancement correlated with the renal cyst size,the type and the enhance phases,which should be considered when making diagnosis.

OBJECTIVETo establish the best hydrolytic conditions from phorbol esters.

METHODThe orthogonal experiment was used to optimize 4 factors, which were reaction time, ratio of solid-to-liquid, hydrolytic times, and temperature. Diamonsil C18 column (4. 6 mm x 250 mm, 5 microm) was used and the mobile phase was consisted of acetonitrile and water for HPLC detection. The detection wavelength was set at 234 nm, the flow rate was 1 mL x min(-1), and the column temperature was 25 degrees C.

RESULTThe optimum conditions were 10 h of reaction time, 1:6 of solid-to-liquid (BaOH/MeOH) ratio, 25 degrees C of temperature, and one time of hydrolysis. There was a good linear relationship of phorbol in the range of 4.28-107 mg x L(-1) (r = 0.999 9), and the average recovery was 97.89%, with RSD 0.78%.

CONCLUSIONThe method is steady, reliable and reproducible, and it provides a mean for future study.

Chromatography, High Pressure Liquid ; Hydrolysis ; Phorbol Esters ; analysis ; chemistry