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Objective To investigate the feasibility and value of CT perfusion imaging in combination of CTA 320-slice CT with dual-low-dose in detection of acute cerebral ischemia.Methods Forty patients with acute stroke underwent perfusion imaging and CTA using a single scan with 320-slice CT with dual-low-dose schedule.CTA,4D-CTA,4D-perfusion imaging and fusion images were generated at a post-processing workstation.All patients also underwent a 3.0T magnetic resonance imaging with DWI for a comparison.Quality of the images,degree of vascular stenosis,and location of ischemic lesions were evaluated.Results The vascu-lar stenosis or occlusion was found in 33 patients,8 of whom were confirmed by the DSA.The ratio of better images of CTA was 82.5%.CTP showed 297 lesions with abnormal perfusion.202 lesions were confirmed as infarct by DWI,while 95 ones were nor-mal on DWI but with increased DLY and TTP and slightly decreased CBF and CBV in 49,increased DLY and TTP and normal CBF and CBV in 21,and increased DLY and TTP and slightly increased CBF and CBV in 25.Conclusion CT perfusion in combination with CTA by 320-slice CT with dual-low-dose is feasible and useful to observe accurately the vascular structures and the ischemic status of the whole brain at early stage.
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Purpose To evaluate the diagnostic significance of non-contrast enhanced magnetic resonance angiography (NCE-MRA) for lower extremity arterial stenosis on a 3.0T MR scanner, in order to provide a reliable method for clinical application. Materials and Methods Thirty patients with arterial disease in lower extremity underwent NCE-MRA before contrast enhanced magnetic resonance angiography (CE-MRA). Image quality of the two methods was compared. The diagnostic accuracy for significant stenosis ( ≥50%) of NCE-MRA was assessed using CE-MRA as a golden standard. The consistency of the two methods in diagnosis of significant stenosis ( ≥ 50%) was analyzed. Results All patients successfully underwent both NCE-MRA and CE-MRA examination. There were 532 arterial segments detected by NCE-MRA. In the calf region, venous artifacts presented more frequently on CE-MRA (Z=4.92, P<0.01), while in the abdominal and the femoral regions, venous artifacts presented more frequently on NCE-MRA (Z=4.58 and 3.56, P<0.01). The sensitivity, specificity, accuracy, positive predictive value and negative predictive value of NCE-MRA for the diagnosis of significant stenosis ( ≥ 50%) were 97.89%, 97.69%, 97.74%, 93.92% and 99.22%, respectively. There was good agreement (Kappa=0.94, P<0.05) between the two methods. Conclusion For the imaging of lower extremity arterial stenosis, NCE-MRA shows similar image quality and diagnostic accuracy with CE-MRA, thus can be used as an alternative method for lower extremity arterial stenosis in patients who have renal insufficiency or other contraindication of contrast media.
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Objective To evaluate dual-source dual-energy CT(DSCT) for the differentiation of urinary stone composition in vitro. Methods Ninety-seven urinary stones were obtained by endoscopic lithotripsy and scanned using dual-source dual-energy CT. The stones were divided into six groups according to infrared spectroscopy stone analysis: uric acid ( UA ) stones ( n = 10 ), cystine stones ( n = 5 ), struvite stones( n = 6), calcium oxalate ( CaOx ) stones ( n = 22 ), mixed UA stones ( n=7 ) and mixed calcium stones(n=47). Hounsfield units (HU) of each stone were recorded for the 80 kV and the 140 kV datasets by hand-drawing method. HU difference, HU ratio and dual energy index ( DEI ) were calculated and compared among the stone groups with one-way ANOVA. Using dual energy software to determine the composition of all stones, results were compared to infrared spectroscopy analysis. Results There were statistical differences in HU difference [(-17±13), (229±34),(309 ±45), (512 ±97), (201±64)and (530±71) HU respectively], in HU ratio (0.96±0.03, 1.34 ±0.04, 1.41 ±0.03, 1.47 ±0.03,1.30±0.07, and 1.49 ±0.03 respectively), and DEI( -0.006 ±0.004, 0.064 ±0.007, 0.080 ±0. 007, 0. 108±0.011 ,0. 055 ±0.014 and 0. 112 ±0.008 respectively ) among different stone groups(F=124. 894,407.028, 322. 864 respectively, P ＜0. 01 ). There were statistical differences in HU difference,HU ratio and DE1 between UA stones and the other groups( P ＜ 0. 01 ). There were statistical differences in HU difference, HU ratio and DEI between CaOx or mixed calcium stones and the other four groups (P＜0. 01 ). There was statistical difference in HU ratio between cystine and struvite stones ( P ＜ 0. 01 ). There were statistical differences in HU difference, HU ratio and DEI between struvite and mixed UA stones (P＜0. 05 ). Dual energy software correctly characterized 10 UA stones, 4 cystine stones, 22 CaOx stones and 6 mixed UA stones. Two struvite stones were considered to contain cystine. One cystine stone, 1 mixed UA stone, 4 struvite stones and 47 mixed calcium stones were considered to contain oxalate. Conclusions DSCT has the ability to differentiate urinary stone composition in vitro. With dual energy software, the UA, cystine and mixed UA stones can be differentiated from other types of stones.
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Objective To evaluate the effieaey of test bolus technique with multi-slice spiral CT (MSCT) for determining the optimal scan delay time in CT Hepatic artery (HA)-portal vein (PV) angiography and multi-phase scanning.Methods MSCT liver angiography and multi-phase scanning were performed in 187 patients divided randomly into two groups.In group A (n =59),the scan delay time was set according to the subjective experiences of operators; in group B (n=128),the scan delay time was determined by test bolus technique.Abdominal aorta and superior mesenteric,vein were selected as target blood vessels,and 50 HU was set as enhancement threshold value.20 ml contrast agent was injected intravenously and time-density curve of target blood vessels were obtained,then HA-PV scanning delay time were calculated respectively.The quality of CTA images obtained by using these 2 methods were compared and statistically analysed using Chi-square criterion.Resuits For hepatic artery phase,the images of group A are:excellent in 34(58%),good in 17(29%),and poor in 8 (13%),while those of group B are excellent in 128( 100%),good in 0(0%),and poor in 0(0%).For portal vein phase,the images of group Aare:excellent in 23(39%),good in 27(46%),and poor in 9(15%),while those of group B are excellent in 96 (75%),good in 28 (22%),and poor in 4 (3%) respectively.There was statistically significant difference between the ratios of image quality in group A and group B (X2=14.97,9.18,P < 0.05).Conclusion Accurate scan delay time was best determined by using test bolus technique,which can improve the image quality of liver angingraphy and multi-phase scanning.