Sun H

[Features of eight segments of liver perfusion with the second generation dual-source computed tomography].

OBJECTIVE To explore the features of eight segments of liver perfusion with the second generation dual-source computed tomography (DSCT) . METHODS Totally 15 patients with pancreatic endocrine diseases underwent abdominal CT perfusion with the second generation DSCT. The liver perfusion images were then transferred to workstation, and perfusion parameters were calculated, and then the artery liver perfusion (ALp) , portal-vein liver perfusion (pVp) , and hepatic perfusion index (HpI) of the eight hepatic segments were calculated. RESULTS ALp was significantly different between segments 3, 4 and segments 5-8 (P<0.05) . pVp was significantly different between segments 2 and segments 6, 7 (P<0.05) . pVp and HpI were significantly different between segment 3 and segments 5-8 (P<0.05,P<0.01) . CONCLUSIONS The second generation DSCT can be used to evaluate the perfusion conditions in all eight hepatic segments. The perfusion differs among eight segments of liver, which may be related with the anatomy of the liver vessels and the position of DSCT scanning. Its clinical significance needs further research.

[Application of dual-energy computed tomography for detecting uric acid deposition in patients with gout].

OBJECTIVE To assess the value of dual energy computed tomography (DECT) for the detection of uric acid (UA) deposition in patients with gout. METHODS A total of 37 patients with tophaceous gout (including 8 crystal-proven cases) and 10 control patients (5 with unknown arthropathy, 3 with rheumatoid arthritis, and 2 with osteoarthritis) were included. DECT was performed for all peripheral joints (wrists, hands, elbows, knees, ankles and feet) . Color coding was used to display the localization of UA deposition. Images were reviewed independently by two trained radiologists. RESULTS With DECT, patients with gout were found to have UA deposits in hands and wrists 46% (17/37) , elbows 16% (6/37) , knees 27% (10/37) , ankles and feet 89% (33/37) . No UA deposit was observed in all 10 control patients (P=0.000) . Among the 37 patients with gout, the number of UA deposition sites detected by DECT (n=297) was 2.25 times of that detected by physical examinations (n=132) (P=0.000) . CONCLUSIONS DECT allows the visualization of UA deposition in gouty arthropathy. Even subclinical disease can be delineated with this technique. However, the accuracy of DECT requires further investigations.

[Dual-energy computed tomographic angiography of head and neck arteries with different contrast material doses in second generation dual-source computed tomography system].

OBJECTIVE To explore the feasibility of a dual-energy computed tomographic angiography (DECTA) protocol using test-bolus injection with reduction of contrast material (CM) dose in second generation dual-source CT system. METHODS Totally 57 consecutive patients underwent CT angiography scan covering the cervical and cerebral arteries. CT was performed with second generation dual-source CT system. The time to peak (T) using a test-bolus injection was calculated. The patients were divided into three groups (A, B, and C) with different CM doses (40, 45, and 50 ml) and different delay time points [ (T+1) , (T+1) , and (T+2) s] . All the patients were followed by a 48 ml saline flush. Arterial enhancements were quantified by measuring attenuation values of the aortic arch, bifurcation of common carotid artery, contralateral internal jugular vein of the CM injection, superior vein cava, proximal middle cerebral artery, basilar artery, and straight sinus on source images. Visualizations of intracranial artery and ipsilateral venous effect of the CM injection were rated on a four-point grading scale on CTA images for qualitative assessment. RESULTS Although the attenuation of internal jugular vein and straight sinus were significantly lower in group A than in groups B and C (P<0.05) , the attenuation of aortic arch, superior vein cava, common carotid artery, middle cerebral artery, and basilar artery vessels showed no significant differences among these three groups. The scores of the visualizations of intracranial artery and ipsilateral venous effect of the CM injection were also not significantly different among these three groups. CONCLUSION Based on the delay time calculated by a test-bolus injection, a reduced-dose contrast material may provide an equal degree of arterial attenuation and a lower attenuation of vein for dual-energy CTA covering the craniocervical region in second generation dual-source CT system.

[Clinical application of high-pitch excretory phase images during dual-source CT urography with stellar photon detector].

OBJECTIVE To retrospectively evaluate the clinical feasibility of high-pitch excretory phase images during dual-source CT urography with Stellar photon detector. METHODS Totally 100 patients received dual-source CT high-pitch urinary excretory phase scanning with Stellar photon detector [80 kV, ref.92 mAs, CARE Dose 4D and CARE kV, pitch of 3.0, filter back projection reconstruction algorithm (FBP)] (group A). Another 100 patients received dual-source CT high-pitch urinary excretory phase scanning with common detector(100 kV, ref.140 mAs, CARE Dose 4D, pitch of 3.0, FBP) (group B). Quantitative measurement of CT value of urinary segments (Hounsfield units), image noise (Hounsfield units), and effective radiation dose (millisievert) were compared using independent-samples t test between two groups. Urinary system subjective opacification scores were compared using Mann-Whitney U test between two groups. RESULTS There was no significant difference in subjective opacification score of intrarenal collecting system and ureters between two groups (all P>0.05). The group A images yielded significantly higher CT values of all urinary segments (all P<0.01). There was no significant difference in image noise (P>0.05). The effective radiation dose of group A (1.1 mSv) was significantly lower than that of group B (3.79 mSv) (P<0.01). CONCLUSION High-pitch low-tube-voltage during excretory phase dual-source CT urography with Stellar photon detector is feasible, with acceptable image noise and lower radiation dose.

Application of single-bolus dual-source dual-energy CT urography in upper tract opacification and diagnostic performance for painless hematuria.

OBJECTIVE To assess the upper urinary tract opacification and the diagnostic performance of one-bolus dual-source dual-energy CT urography (CTU) for painless hematuria. METHODS Totally 205 patients who underwent dual-source dual-energy CTU for painless hematuria were enrolled in this study. CTU included true non-enhanced phase, dual-energy mode nephrographic phase, and FLASH mode excretory phase imaging of the urinary tract. Two radiologists independently evaluated the degree of upper urinary tract opacification. Prospective interpretations using true non-enhanced, nephrographic and excretory phase imaging for hematuria were recorded, as well as retrospective diagnosis using virtual non-enhanced, nephrographic and excretory phase imaging. The standard of reference included all available clinical, imaging, laboratory and follow-up data for up to 36 months after CTU exam. Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values, and accuracy were calculated. Receiver-operating characteristic (ROC) analysis was undertaken and the area under the curve (AUC) calculated. The prospective and retrospective diagnostic performance for hematuria and the radiation dose of two CTU protocols were compared. RESULTS It was found that 87.8% and 86.8% of segments were at least 50% opacified, respectively. The sensitivity, specificity, PPV, NPV and accuracy for hematuria for prospective interpretation were 95.2%, 91.9%, 98.2%, 81.0% and 94.6%, respectively. Comparable figures for retrospective diagnosis were 98.8%, 91.9%,98.2%, 94.4% and 97.6%. The AUC for prospective and retrospective diagnosis were 0.931±0.027 and 0.940±0.026, respectively (z=1.425, Bonferroni-corrected P>0.05). The radiation dose of the CTU protocol using in retrospective diagnosis[(12.732±3.485)mSv] was significantly lower than that of prospective diagnosis [(17.002±4.013)mSv] (P<0.05), with dose reduction of (32.74±8.92)%. CONCLUSION One-bolus two-phase dual-source dual-energy CT urography provides at least 50% opacification of upper urinary tract segments and has high diagnostic performance for painless hematuria with relatively low radiation dose.

[Application of second generation dual-source computed tomography dual-energy scan mode in detecting pancreatic adenocarcinoma].

OBJECTIVE To analyze the clinical value of multiple sequences derived from dual-source computed tomography (DSCT) dual-energy scan mode in detecting pancreatic adenocarcinoma. METHODS Totally 23 patients with clinically or pathologically diagnosed pancreatic cancer were enrolled in this retrospective study. DSCT (Definition Flash) was used and dual-energy scan mode was used in their pancreatic parenchyma phase scan (100kVp/230mAs and Sn140kVp/178mAs) . Mono-energetic 60kev, mono-energetic 80kev, mono-energetic 100kev, mono-energetic 120kev, linear blend image, non-linear blend image, and iodine map were acquired. pancreatic parenchyma-tumor CT value difference, ratio of tumor to pancreatic parenchyma, and pancreatic parenchyma-tumor contrast to noise ratio were calculated. One-way ANOVA was used for the comparison of diagnostic values of the above eight different dual-energy derived sequences for pancreatic cancer. RESULTS The pancreatic parenchyma-tumor CT value difference, ratio of tumor to pancreatic parenchyma, and pancreatic parenchyma-tumor contrast to noise ratio were significantly different among eight sequences (P<0.05) . Mono-energetic 60kev image showed the largest parenchyma-tumor CT value [ (77.53 ± 23.42) HU] , and iodine map showed the lowest tumor/parenchyma enhancement ratio (0.39?0.12) and the largest contrast to noise ratio (4.08 ± 1.46) . CONCLUSIONS Multiple sequences can be derived from dual-energy scan mode with DSCT via multiple post-processing methods. Integration of these sequences may further improve the sensitivity of the multislice spiral CT in the diagnosis of pancreatic cancer.