ABSTRACT
This study was performed to optimize scan delays for canine kidney by using a bolus-tracking technique. In six beagle dogs, computed tomography (CT) of the kidney was performed three times in each dog with different scan delays after a bolus-tracking trigger of 100 Hounsfield units (HU) of aortic enhancement. Delays were 5, 20, 35, and 50 sec for the first scan, 10, 25, 40, and 55 sec for the second scan, and 15, 30, 45, and 60 sec for the third scan. The renal artery-to-vein contrast difference peaked at 5 sec, and the renal cortex-to-medulla contrast difference peaked at 10 sec. The renal cortex-to-medulla contrast difference approached zero at a scan delay of 30 sec after the bolus trigger. For the injection protocol used in this study, the optimal scan delay times for renal arterial, corticomedullary, and nephrographic phases were 5, 10, and 30 sec after triggering at 100 HU of aortic enhancement using the bolus-tracking technique. The bolus-tracking technique is useful in multi-phase renal CT study as it compensates for different transit times to the kidney among different animals, requires a small dose of contrast media, and does not require additional patient radiation exposure.
Subject(s)
Animals , Dogs , Humans , Contrast Media , Kidney , Radiation ExposureABSTRACT
Objective To discuss the feasibility of double-low technique applied in aortic MSCTA.Methods Totally 70 patients with BMI not more than 25 kg/m2 were divided into a routine group and an experimental group randomly and equally,and then went through aortic MSCTA.Iohexol (350 mgI/ml) was injected with the velocity of 4 ml/s.The routine group had the parameters as 120 kV,120 mAs and 1.5 ml/kg contrast agent,and the experimental group had the parameters as 90 kV,120 mAs and 1.0 ml/kg contrast agent,while the other scanning parameters were kept the same in the two groups.The radiation doses,contrast agent doses and iodine contents were recorded in the two groups,and the image quality was assessed with double-blind method objectively and subjectively.Results The experimental group had the CT dose index volumes (CTDIvol),dose length product (DLP) and effect dose (ED) significantly lower than those in the routine group (P＜0.05).The two groups had the consistency of subjective scores (Kappa＞0.6) and image quality scores (not lower than 2) meet the desired requirements,and there were no significant differences between the scores (P＞0.05).Objective evaluation showed that the signal values of aortic trunk and major branch vessels as well as image noise SD of the experimental group were obviously higher than those in the routine group (P＜0.05).There were no statistical differences between the signal noise ratios (SNR) and contrast to noises (CNR) in the two groups (P＞0.05),The iodine content in the contrast agent of the experimental group was significantly lower than that in the routine group (P＜0.05).Conclusion Double-low technique applied in aortic MSCTA of the patient with BMI not more than 25 kg/m2 reduces the radiation dose and iodine content in the contrast agent,has the image quality meet the desired requirements,and thus is of great value for clinical application.
ABSTRACT
This study was conducted to establish the values for optimal fixed scan delays and diagnostic scan delays associated with the bolus-tracking technique using various contrast material injection durations in canine abdominal multi-phase computed tomography (CT). This study consisted of two experiments employing the crossover method. In experiment 1, three dynamic scans at the porta hepatis were performed using 5, 10 and 15 sec injection durations. In experiment 2, two CT scans consisting of five multi-phase series with different scan delays of 5 sec intervals for bolus-tracking were performed using 5, 10 and 15 sec injection duration. Mean arrival times to aortic enhancement peak (12.0, 15.6, and 18.6 sec for 5, 10, and 15 sec, respectively) and pancreatic parenchymal peak (17.8, 25.1, and 29.5 sec) differed among injection durations. The maximum mean attenuation values of aortas and pancreases were shown at the scan section with 0 and 5, 0 and 10 and 5 and 10 sec diagnostic scan delays during each injection duration, respectively. The optimal scan delays of the arterial and pancreatic parenchymal phase in multi-phase CT scan using fixed scan delay or bolus-tracking should be determined with consideration of the injection duration.
Subject(s)
Animals , Dogs , Aorta , Liver , Methods , Pancreas , Tomography, X-Ray ComputedABSTRACT
Objective To investigate the feasibility of reducing bolus?tracking monitor frequency in coronary CT angiography (CTA). Methods This prospective study including 120 patients with suspected coronary artery disease (CAD). According to the examination registration order, the patients were divided into groups A, B and C (n=40 for each group). All patients underwent coronary CTA with bolus?tracking technology, and were monitored at 10 s after the injection of contrast. The monitoring frequency of bolus?tracking for Group A was every 1.14 s, that for Group B was every 1.47 s , and for Group C was every 2.00 s, while the trigger threshold was set as 100 HU. To evaluate the image quality, the objective evaluation included signal noise ratio (SNR) and contrast noise ratio (CNR) of aorta (AO), CNR of left main coronary artery (LM) and right coronary artery (RCA), and the subjective score was recorded for each coronary artery segment. The monitoring times when CT density of the region of interest (ROI) reached the threshold, the CT value and the effective dose (ED) in the 3 groups were recorded. Objective image quality, monitoring parameters and radiation dose were compared using analysis of variance method, subjective image quality was compared withχ2 tests. Results There was no significant difference in AO (SNR and CNR), LM (CNR) and RCA (CNR) among the 3 groups, respectively (P>0.05). Subjective image quality scores of groups A, B, C were (1.879±0.042), (1.876±0.042), (1.881±0.042 ), with no significant difference (χ2=0.003,P>0.05). The monitoring times of to reach the threshold in groups A, B, C were (4.78±2.37), (3.76±1.39), (2.77±0.99), and ED were (0.058±0.031),(0.031±0.011), (0.021±0.007) mSv, with the significant difference (F=9.009, 31.998, respectively, P<0.01). Peak CT values during monitoring among three groups were (133 ± 24), (142 ± 39), (137±26) HU, respectively, with no significant difference (F=0.575,P=0.565). Conclusions It is feasible to reduce monitoring times when performing coronary CTA in dual?source CT scanner. The bolus?tracking monitor frequency in every 2 seconds can not only obtain satisfactory image quality, but also significantly reduce radiation dose.
ABSTRACT
Objective: To evaluate the application value of CT enhancing scan based on bolus tracking technology in the upper abdomen. Methods:200 patients were examined by CT in the upper abdomen. Contrast agent was injected through the hand vein at 1.5 ml/kg, with pressure of 300 Pa, flow rate 2.5 ml/s. Before injection, we must complete the first scanning .Then , another 2 or 3 scans were done. Results:188 cases can show abdominal aorta, hepatic artery, splenic artery, hilar vessel branches, portal vein, inferior vena cava very well. Another two cases failed .The others were not ideal because of portal hypertension. Conclusion:CT enhancing scan based on bolus tracking technique in the upper abdomen can obtain good images to meet clinical needs.
ABSTRACT
Objective: To optimize the delay time before the initiation of arterial phase scan in the detection of focal liver lesions in contrast enhanced 5 phase liver CT using the bolus tracking technique. Patients and Methods: Delay - the interval between threshold enhancement of 100 hounsfield unit (HU) in the abdominal aorta and commencement of the first arterial phase scan. Using a 16 slice CT scanner, a plain CT of the liver was done followed by an intravenous bolus of 120 ml nonionic iodinated contrast media (370 mg I/ml) at the rate of 4 mL/s. The second phase scan started immediately after the first phase scan. The portal venous and delay phases were obtained at a fixed delay of 60 s and 90 s from the beginning of contrast injection. Contrast enhancement index (CEI) and subjective visual conspicuity scores for each lesion were compared among the three groups. Results: 84 lesions (11 hepatocellular carcinomas, 17 hemangiomas, 39 other hypervascular lesions and 45 cysts) were evaluated. CEI for hepatocellular carcinomas appears to be higher during the first arterial phase in the 6 seconds delay group. No significant difference in CEI and mean conspicuity scores among the three groups for hemangioma, other hypervascular lesions and cysts. Conclusion: The conspicuity of hepatocellular carcinomas appeared better during the early arterial phase using a bolus tracking technique with a scan delay of 6 seconds from the 100 HU threshold in the abdominal aorta.
ABSTRACT
Objective To evaluate stepping DSA technology in lower extremity artey disease. Methods 12 cases performed with stepping DSA in lower extremity artery were examined with TOSHIBA Infinixi digital subtraction angiography system, of which, 8 ones were also examined with conventional DSA. Results Stepping DSA technology could decrease the dosage of contrast agent and the examination.