Prospective randomized study for an injection protocol for intravenous contrast media in abdominal and pelvic helical CT.

OBJECTIVE: To develop an injection protocol for intravenous administration of contrast media in abdominal and pelvic helical CT which provides optimal contrast enhancement of arterial and venous vessels. MATERIAL AND METHODS: For the study on a Somatom Plus 4 unit, a standard helical CT examination procedure of abdomen and pelvis consisted firstly of a native helical examination of the liver, a second one of the liver after intravenous injection of 120 ml nonionic contrast medium with a constant start delay of 50 s, and subsequently a third helical CT of the lower abdomen and pelvis. 125 patients were randomized for examination under different protocols, varying the injection flow from 2.0-4.0 ml/s and the time delay between the second and the third helical examinations from an additional 20-40 s. The efficacy of the contrast injection was checked by region of interest (ROI) measurements of HUs in aorta, inferior vena cava, and in femoral arteries and veins. The results were compared by t-test statistics. RESULTS: A slow flow rate of 2.0 ml/s led to a higher contrast enhancement in the aorta than a flow rate of 3.0 and 4.0 ml/s. The difference between 2.0 ml/s and 4.0 ml/s was statistically significant. In the inferior vena cava, a flow of 3.0 ml/s caused a better contrast than a flow of 2.0 ml/s or 4.0 ml/s, but the measurements did not reach statistical significance. The measurements in the femoral arteries and veins did not show any significant differences. Maximal enhancement in the pelvic vessels was achieved when the third helical examination was started immediately after the second one had ended. Adding any delay (20 s, 40 s) led to a reduced contrast in the pelvic vessels, with a significant reduction in aorta and femoral arteries. CONCLUSION: For routine abdominal and pelvic helical CT, we recommend an injection of 120 ml contrast medium with a flow rate of 3.0 ml/s. Contrast-enhanced examination of the liver should be started after 50 s, and examination of the lower abdomen and pelvis region should be performed without any further delay. This gives an appropriate contrast in the major vessels.     

Preliminary examination to determine the suitable contrast material injection protocol for CT angiography of the pelvis and lower extremities with a multidetector row helical scanner

Purpose The aim of this study was to determine the best of three protocols for the depiction of arteries in the pelvis and lower extremities by computed tomographic angiography (CTA) with a multidetector row helical scanner. Materials and methods CTA was performed in five asymptomatic volunteers using a four-channel multidetector row helical scanner. Low-osmolar iodinated contrast material was injected at the flow rate of 3 ml/s using three protocols: 100 ml of 300 mg I/ml, 150 ml of 300 mg I/ml, and 100 ml of 350 mg I/ml. The CT number of opacified blood was measured at six levels. Three doctors independently assessed the degree of depiction of arteries on CTA images without knowing the protocol using a 3-point scale. Results CT numbers at the level of the popliteal artery on the protocol of 150 ml of 300 mg I/ml were significantly greater than the others. The mean score for the depiction of trifurcation on the protocol of 150 ml of 300 mg I/ml was significantly greater than those in the others. Conclusion The protocol of 150 ml of 300 mg I/ml was the best for depicting arteries in the pelvis and lower extremities by CTA.     

心脏CT检查时对比剂注射方案的优化

多层螺旋CT（MSCT）的间世拓展了CT在心脏检查中的应用范围,新一代MSCT尤其是64层以上的螺旋CT,因其良好的时间分辨力、空间分辨力及密度分辨力,得到了临床医生的广泛认可。冠状动脉CT血管成像（CCTA）对冠状动脉疾病的诊断,其阴性预测值可达到98％～99％,与传统冠状动脉造影相比,MSCT对冠心病的筛查、斑块及组成成分的观察、斑块危险度的预测、     

Effect of contrast injection protocol with dose tailored to patient weight and fixed injection duration on aortic and hepatic enhancement at multidetector-row helical CT

The aim of this study was to investigate the effect of a contrast material injection protocol with dose and injection rate of contrast material tailored to patient weight (dose tailored to patient weight and fixed injection duration). Hepatic helical CT was performed in 92 patients with chronic liver damage with a dose of 1.4 ml (518 mgI) at a rate of 0.056 ml/s per kilogram body weight of Iopamidol 370. Attenuation values of liver and aorta were measured for calculation of maximum aortic and hepatic enhancement, time to maximum hepatic enhancement, and end of hepatic arterial phase. Correlation coefficients between the injection rate and the four parameters were r=0.008, 0.057, 0.167, and 0.036, and there were no statistically significant correlations between the injection rates and the four parameters. In our injection protocol, uniform temporal scan window may be achieved and the injection rate can be reduced in lighter patients without reducing the degree of enhancement in the aorta and the liver.     

口服对比剂螺旋CT胆管成像术

目的：初步探讨并优化口服对比剂螺旋CT胆管成像技术（OCHCTC）的要点、可行性以及图像质量。方法：36例健康志愿随机分成两组，分别口服3g和6g碘番酸，于12h、14h及口服高脂餐后分别扫描、重建。观察服药时间、剂量和高脂餐与胆管显影的关系。结果：碘番酸不良反应少而轻；当碘番酸用量6g、扫描时间12h时，胆管系统显影较好。而进食高脂餐对显影无太大意义。结论：OCHCTC是一种安全可靠、简便易行的胆管系统无创检查技术，3D图像可满意显示胆管解剖结构，有较好的应用前景。     

Acute appendicitis: comparison of helical CT diagnosis focused technique with oral contrast material versus nonfocused technique with oral and intravenous contrast material

PURPOSE: To compare the diagnostic accuracy of focused helical computed tomography (CT) with orally administered contrast material with that of nonfocused helical CT with orally and intravenously administered contrast material. MATERIALS AND METHODS: After receiving oral contrast material, 228 patients with clinically suspected appendicitis underwent focused appendiceal CT (5-mm section thickness, 15-cm coverage in the right lower quadrant). Immediately thereafter, helical CT of the entire abdomen and pelvis was performed following intravenous administration of contrast material (abdomen, 7-mm section thickness; pelvis, 5-mm section thickness). Studies were separated and independently interpreted by three observers who were blinded to patient names. Diagnoses were established by means of surgical and/or clinical follow-up findings. RESULTS: Fifty-one (22.4%) of 228 patients had acute appendicitis. Readers diagnosed appendicitis with 83.3%, 73.8%, and 71.4% sensitivity and 93.0%, 92.3%, and 97.9% specificity with focused nonenhanced appendiceal CT. Readers diagnosed appendicitis with 92.9%, 92.9%, and 88.1% sensitivity and 93.7%, 95.1%, and 96.5% specificity with nonfocused enhanced CT. Summary areas under the receiver operating characteristic curve estimates for focused nonenhanced and nonfocused enhanced CT were 0.916 and 0.964, respectively; the differences were statistically significant (P <.05) for two of three readers. All readers demonstrated higher sensitivities for detecting the inflamed appendix with nonfocused enhanced CT. Appendicitis was missed with focused CT in two patients whose inflamed appendix was not included in the imaging of the right lower quadrant. All readers were significantly more confident in diagnosing alternative conditions with nonfocused enhanced CT. CONCLUSION: Diagnostic accuracy of helical CT for acute appendicitis improved significantly with use of intravenous contrast material.     

Optimal protocol for injection of contrast material at MR angiography: study of healthy volunteers

Forty healthy volunteers, matched for age and body weight, underwent abdominal magnetic resonance angiography with gadopentetate dimeglumine administered by using a power injector. Injection rates were 0.3, 1.0, 2.0, or 3.0 mL/sec. Contrast material doses were 0.1 (single dose) or 0.2 (double dose) mmol/kg. Increased contrast enhancement in the aorta and minimum arteriovenous overlap can be achieved with high flow rate and double-dose injection.     

Evaluation of suspected appendicitis in children using limited helical CT and colonic contrast material

OBJECTIVE. Colonic contrast material evaluation of suspected appendicitis in pediatric patients is technically more challenging than in adults because less intraabdominal fat is present. To determine the accuracy and feasibility of focused CT for pediatric patients, we carried out this retrospective investigation. MATERIALS AND METHODS. Between November 1995 and July 1999, 199 pediatric patients (1-18 years old; mean age, 12 years) were examined with focused CT in the emergency division for suspected appendicitis. The findings on CT were compared with the findings at surgery, pathology, and clinical follow-up. RESULTS. There were 64 true-positive CT scans, two false-negative, 128 true-negative, one false-positive, and four indeterminate. Seventy-four patients underwent appendectomy, with a negative appendectomy rate of 9%. One hundred twenty-five patients without appendicitis were treated nonoperatively. The true-positive rate was 32%, true-negative rate was 64%, sensitivity was 97%, specificity was 99%, positive predictive value was 98%, negative predictive value was 98%, and overall accuracy was 96%. Pediatric patients tolerated the procedure well. Colonic contrast material saved time and provided improved identification of the cecum and appendix. In 62 patients without appendicitis, focused CT provided alternative diagnoses. CONCLUSION. Focused CT appears to be nearly as accurate in pediatric patients as in adults. Focused CT provided alternative diagnoses in 48% of the patients for whom CT findings were negative for appendicitis.     

Flash 双源对比剂优化方案在冠状动脉成像中的应用

目的：探讨 Flash 双源对比剂优化方案在冠状动脉 CT 血管造影(CTA)中的应用价值。方法252例临床疑冠心病行冠状动脉 CTA 检查者,根据体重分组个体化注射对比剂,分别测量升主动脉近端,右冠状动脉主干近段及左冠状动脉主干的 CT值,并对图像质量进行主观评分。结果据本方案行冠状动脉 CTA 检查后,各组升主动脉近端平均 CT 值(HU)分别为399.35±58.55、416.10±49.79、419.39±47.40、405.71±55.44、396.81±49.16;右冠状动脉主干近段平均 CT 值分别为405.6±61.71、421.60±58.89、423.88±53.59、407.7±58.45、405.32±55.84;左冠状动脉主干平均 CT 值分别为397.54±60.59、423.41±53.08、422.74±50.29、409.49±60.05、402.80±54.80。冠状动脉图像质量评分分别为4.59±0.31、4.66±0.25、4.64±0.32、4.63±0.51、4.62±0.43,组间差异无统计学意义(F =1.81,P >0.05)。结论应用 Flash 双源个体化注射方案行冠状动脉 CTA 检查不仅可以满足诊断要求,还可以使对比剂的用量降低,具有良好的可行性。     

Body weight-tailored contrast material injection protocol for 64-detector row computed tomography coronary angiography

Purpose  

The aim of this study was to assess the body weight-tailored contrast material injection protocol for 64-detector computed tomography (CT) to maintain optimal coronary CT attenuation.     

Pancreatic CT imaging: effects of different injection rates and doses of contrast material.

PURPOSE: To assess the effects of the intravenous injection rate and dose of contrast material on pancreatic computed tomography (CT). MATERIALS AND METHODS: A total of 126 patients were divided at random into four groups with different injection rates and doses. Groups 1 and 2 underwent injection of 2 mL per kilogram of body weight of 300 mg of iodine per milliliter of contrast material, and groups 3 and 4 underwent injection of 1.5 mL/kg. The injection rate was 5 mL/sec for groups 1 and 3 and 3 mL/sec for groups 2 and 4. Single-level serial CT scanning was performed at the level of the pancreatic head, and the pancreatic enhancement value was calculated. RESULTS: The maximum pancreatic enhancement value was 99 HU +/- 18 (mean +/- SD) for group 1, 90 HU +/- 18 for group 2, 86 HU +/- 15 for group 3, and 74 HU +/- 13 for group 4. There were significant differences in the maximum pancreatic enhancement value between groups 1 and 2 (P = .045), between groups 3 and 4 (P = .001), between groups 1 and 3 (P = .016), and between groups 2 and 4 (P = .001). CONCLUSION: Both a higher dose and a faster injection rate increased the maximum pancreatic enhancement value.