Evaluation of required saline volume in dynamic contrast-enhanced computed tomography using saline flush technique

The present study was performed to find the required volume of physiological saline for flushing that will allow the most efficient use of contrast medium during the early phase of dynamic CT. We calculated contrast medium aortic arrival time (AT), time to peak aortic enhancement (TPAE) and the elapsed time to TPAE from AT (rise time) from the TECs of pharmacokinetic analysis and clinical study. The rise time determined in the clinical study was 6.2 s, which was shorter than that in the simulation study. In the present study, an appropriate volume for saline flush was estimated to be about 18 ml.     

Abdominal multidetector row computed tomography: reduction of cost and contrast material dose using saline flush

OBJECTIVE: To evaluate the potential of a saline solution flush after the contrast material bolus in abdominal multidetector row CT (MDCT) in contrast material dose and cost reduction. METHODS: Abdominal MDCT was performed in 78 patients who were assigned randomly to 2 groups receiving 120 mL nonionic contrast material (300 mgI/mL) alone or 100 mL of the same contrast material pushed with 40 mL of saline solution. Mean attenuation values for both groups were measured in the liver, the spleen, the pancreas, the portal vein, the inferior vena cava, and the abdominal aorta. Cost analyses were performed for both groups. RESULTS: There was no significant difference in parenchymal and vascular enhancement between both groups. The difference of the enhancement was 2 HU for the liver (P = 0.11), 2 HU for the spleen (P = 0.44), 3 HU for the pancreas (P = 0.38), 9 HU for the portal vein (P = 0.11), 3 HU for the inferior vena cava (P = 0.55), and 10 HU for the aorta (P = 0.06). Taking the costs of contrast material, saline solution, and disposal material into account, 7.30 dollars was saved by the patient using a saline solution flush. CONCLUSIONS: Using a saline flush after the contrast material bolus in abdominal MDCT allows an iodine dose reduction of approximately 6 g, or 17%, without impairing mean parenchymal and vascular enhancement and a cost reduction of 7.30 dollars per patient.     

Usefulness of a saline flush for intravenous 3-dimensional computed tomography portography using multidetector-row helical computed tomography

PURPOSE: To evaluate the clinical usefulness of a saline flush technique in improving the imaging quality of 3-dimensional computed tomography portography (3D-CTP). METHODS: To evaluate liver metastases, 58 patients were divided into 2 groups undergoing 3D-CTP with or without a saline flush. The computed tomography (CT) values of the right portal vein (RPV), left portal vein (LPV), main portal vein (MPV), and right hepatic parenchyma (RHP) were assessed. Maximum intensity projection (MIP) 3D-CTP images were evaluated by vessel visualization. RESULTS: Higher mean CT attenuation values in the RPV, LPV, MPV, and RPV-RHP were observed in the saline flush group and were statistically significant (P = 0.04, P = 0.03, P = 0.01, and P = 0.04, respectively). The difference in imaging quality between 2 groups was statistically significant (P = 0.04). In segment VIII, the ability to depict the segmental branches was significantly higher when the saline flush technique was used (P = 0.03). CONCLUSIONS: The saline flush technique increases the CT attenuation values of the portal vein and the difference in values between the portal vein and the tissue around it and improves the MIP imaging quality of 3D-CTP.     

多排螺旋CT腹部增强扫描中使用生理盐水冲刷对比剂技术的评价

目的比较不同量的对比剂追加盐水后,在腹部增强扫描中对各脏器和血管的影响程度,以期达到不影响强化、减少副作用且减少造影剂用量的目的。方法75例受检者分为3组,A组单独注射对比剂100mL组,B组注射对比剂80mL追加盐水20mL组和C组注射对比剂70mL追加盐水30mL组。在常规动脉期33s和门脉期80s进行扫描。测量肝脏、脾脏、胰腺、肾脏门脉主干、主动脉及下腔静脉的CT值,比较3组间的不同。结果脾脏、胰腺、肾脏、门静脉和主动脉各门脉期在3组间均有统计学差异,进行两两比较结果表明,脾脏、胰腺、肾脏、门静脉和主动脉各门脉期在A和C组间有统计学差异,而胰腺和肾脏在门脉期仅在A和B组间无统计学差异。结论腹部MDCT扫描中,使用对比剂追加盐水冲刷技术,可减少对比剂的用量,减少肾毒性。     

Use of a power injector during dynamic computed tomography

We instituted the use of a power injector during dynamic body CT to improve control of the rate of contrast injection, to make it unnecessary for a technologist to remain in the gantry room during scanning, and to make it possible for one technologist to simultaneously perform the injection and operate the scanner. We analyzed the first 240 cases using the power injector for quality of contrast enhancement and frequency of complications, including contrast material extravasation into soft tissues. Ninety-seven percent of the studies had enhancement judged good, very good, or excellent. A technologist remained in the gantry room during some portion of the examination in only 11% of the studies. Minor contrast material extravasation occurred in two cases and major extravasation in one case, a frequency of 1.3%. None of these resulted in long-term morbidity.     

Aortoiliac enhancement during computed tomography angiography with reduced contrast material dose and saline solution flush: influence on magnitude and uniformity of the contrast column

RATIONALE AND OBJECTIVES: To compare the magnitude and uniformity of aortoiliac contrast enhancement obtained from uniphasic contrast material injections versus contrast material injections with reduced iodine dose followed by a saline flush in aortoiliac multislice CT angiography (CTA). METHODS: Twenty-nine patients with abdominal aortic aneurysms underwent aortoiliac CTA using protocols A and B. With protocol A, 120 mL contrast material (300 mgI/mL), and with protocol B, 100 mL contrast material followed by a 40-mL saline solution flush were administered at a flow rate of 4 mL/s. Quantitative analysis was performed by calculating mean aortoiliac attenuation, mean plateau deviation, and mean difference between maximum and minimum attenuation value for both groups. Qualitative analysis was performed by visual assessment of vascular enhancement using 2-dimensional and 3-dimensional postprocessing techniques. RESULTS: The mean aortoiliac attenuation with protocol A was 291 +/- 62 HU, and with protocol B it was 285 +/- 61 HU. The difference of 6 HU was not statistically significant (P = 0.27). Mean plateau deviation was significantly smaller using protocol A than protocol B (16 +/- 9 HU vs. 20 +/- 10 HU, P = 0.03). In addition, the mean difference between maximum and minimum attenuation value was significantly smaller with protocol A than with protocol B (59 +/- 29 HU vs. 72 +/- 32 HU, P = 0.01). Visual analysis showed no difference in contrast material magnitude and homogeneity between the protocols. CONCLUSIONS: In aortoiliac CTA, a saline solution flush after contrast material bolus allows an iodine dose reduction of approximately 20 mL without impairing the magnitude of contrast enhancement but degrades the uniformity of the contrast column. However, the degradation does not affect visual analysis.     

Effect of saline pushing after contrast material injection in abdominal multidetector computed tomography with the use of different iodine concentrations

Purpose: To investigate whether saline pushing after contrast material improves hepatic vascular and parenchymal enhancement, and to determine whether this technique permits decreased contrast material concentration.

Material and Methods: 120 patients who underwent hepatic multidetector computed tomography were divided randomly into four groups (Groups A-D): receiving 100 ml of contrast material (300 mgI/ml) only (A) or with 50 ml of saline solution (B); or 100 ml of contrast material (350 mgI/ml) only (C) or with 50 ml of saline solution (D). Computed tomography (CT) values of the aorta in the arterial phase, the portal vein in the portal venous inflow phase, and the liver in the hepatic phase were measured. Visualization of the hepatic artery and the portal vein by 3D CT angiography was evaluated as well.

Results: Although the enhancement values of the aorta were not improved significantly with saline pushing, they continued at a high level to the latter slices with saline pushing. The enhancement value of the portal vein increased significantly and CT portography was improved with saline pushing. The enhancement value of the liver was not improved significantly using saline pushing. In a comparison between groups B and C, the enhancement values of the aorta and portal vein and the visualization of CT arteriography and portography were not statistically different.

Conclusion: The saline pushing technique can contribute to a decrease in contrast material concentration for 3D CT arteriography and portography.     

Effect of oral contrast for abdominal computed tomography on emergency department length of stay

Computed tomography of the abdomen and/or pelvis (CTAP) is frequently used in the emergency department (ED) allowing diagnosis of a variety of conditions, but requiring a prolonged period of preparation. To determine whether not requiring oral contrast for CTAP reduces ED length of stay (LOS). Retrospective cohort of adult patients visiting an academic ED over 13 weeks around a radiology protocol change. Before the change, many CTAPs required oral contrast; thereafter, oral contrast was not required. LOS was compared before and after the change among all adult ED patients. Among patients undergoing CTAP, adjusted LOS and time to CTAP were compared using multivariate linear regression. 20,464 adult ED visits occurred over the study period, including 1,806 where a CTAP was performed. Oral contrast usage decreased from 42.5% of CTAP to 12.2% (difference 30.3%, 95% confidence interval 38.7% to 46.3%). There was no change in LOS among all ED visits. Among ED visits where a CTAP was performed, median time to CTAP decreased by 27 min and median LOS decreased by 30 min. Adjusted LOS decreased from 324 min (312–337) to 297 min (285–309). Not routinely requiring oral contrast for CTAP in the ED is associated with a half-hour reduction in LOS among all patients undergoing CTAP.     

Reduction of contrast material dose and artifacts by a saline flush using a double power injector in helical CT of the thorax

OBJECTIVE: Our objective was to evaluate a combined method of contrast material bolus followed by saline solution flush for thoracic helical CT and statistical comparison with a uniphasic injection protocol. MATERIALS AND METHODS: Fifty patients underwent helical CT of the thorax using 60 ml of contrast material (370 mg I/ml) followed by flushing with 30 ml of physiologic saline solution. These 50 patients had been examined before using our previous protocol, 75 ml of the same contrast material without a subsequent saline solution. Mean attenuation values for both protocols were measured in the superior vena cava, the pulmonary trunk, and the ascending aorta. Image artifacts and mediastinal and hilar depiction were graded and compared. RESULTS: Mean attenuation values in the superior vena cava were considerably higher in the regimen without saline solution flush (459 H versus 352 H) and in the pulmonary trunk and the ascending aorta were almost identical for both protocols. Injection of saline solution diminished surrounding artifacts (p = 0.001). Grading results for the evaluation of mediastinal and hilar structures were not significantly different in the two protocols (p = 0.564). CONCLUSION: Injection of contrast material followed by a saline solution bolus using a double power injector when performing thoracic helical CT allows a 20% reduction of contrast material volume to 60 ml with a similar degree of enhancement. In addition, perivenous artifacts in the superior vena cava are significantly reduced.     

Patterns of brain perfusion: dynamic computed tomography using intravenous contrast enhancement.

A representation of cerebral perfusion is obtained using cranial computed tomography following the rapid bolus injection of iodinated intravenous contrast medium. This technique permits the definition of four gross patterns of perfusion (normal, circulatory arrest, hypoperfusion, and hyperperfusion). This classification is affirmed in an experimental model of cerebral infarction in the baboon. The limitations of dynamic imaging using computed tomography are reviewed.     

Inferior vena cava pseudothrombus in computed tomography using a contrast medium power injector: a potential pitfall

Of 276 patients undergoing CT using a power injector to deliver contrast material, 71 (26%) demonstrated a pseudothrombus in the suprarenal inferior vena cava. This occurs much more commonly than in patients injected by hand and is a potential pitfall in interpreting these scans.     

Active extravasation of arterial contrast agent on post-traumatic abdominal computed tomography.

OBJECTIVE: To evaluate the use of emergent dynamic intravenous contrast-enhanced computed tomography (CT) in the diagnosis of active arterial extravasation in patients admitted to hospital after blunt abdominal trauma. METHODS: Four-hundred and ninety-eight consecutive emergent contrast-enhanced computed tomographic images of the abdomen and pelvis were retrospectively reviewed. The presence of and site(s) of active arterial extravasation were recorded. Two radiologists reviewed the images and compared the site(s) of extravasated arterial contrast agent with the site(s) of active hemorrhage established at angiography (n = 9) or surgery (n = 4). RESULTS: Twenty-eight patients' computed tomographic images were identified as showing signs of extravasation of contrast agent representing active arterial bleeding. A total of 49 sources of active arterial extravasation were identified, 37 in 19 patients. A pelvic source of active arterial hemorrhage was most frequent and was typically associated with unstable pelvic fractures (n = 18). Other sources of active arterial hemorrhage included the liver (n = 3), spleen (n = 2), retroperitoneum (n = 1), kidney (n = 1), mesentery (n = 1), abdominal wall (n = 3) and lumbar region (n = 1). Only 9 of 28 patients became sufficiently hemodynamically unstable to warrant angiography. All 9 patients had a pelvic source of arterial extravasation on contrast-enhanced CT, and 7 demonstrated active bleeding requiring embolization. The contrast-enhanced computed tomographic images correctly indicated the anatomical source of bleeding in all 7 cases. CONCLUSION: In patients who have experienced blunt abdominal trauma, attention should be paid to the computed tomographic features of active arterial hemorrhage. In our series, the pelvis was the most common source of active arterial bleeding, which was typically associated with unstable pelvic fractures.     

Non-absorbable fat-dense oral contrast agent for abdominal computed tomography.

Opacification of the gastrointestinal tract for CT scanning is usually achieved by oral administration of a diluted iodine solution or barium suspension. As high-density contrast agents often cause image degrading artifacts, we investigated the value of a paraffin-methylcellulose emulsion as an oral CT scanning agent. Diseases of the intestinum were clearly outlined with paraffin emulsion, and image degrading artifacts were virtually not encountered.     

Measurement of regional changes in myocardial perfusion using dynamic computed tomography and contrast medium

Changes in regional myocardial perfusion were measured using rapid sequence dynamic transmission tomography to detect differences in the initial distribution of contrast medium injected as an intravenous bolus. The experiments were carried out on 8 mongrel dogs instrumented with flow probes and vascular occluders around the coronary arteries. Flow reductions of 50 per cent or more were detected as regions of myocardium with less contrast enhancement than those with normal perfusion. Reactive hyperemia induced by transient ischemia was detected as areas of relatively increased contrast enhancement. These changes could be demonstrated on the images and quantitated using data depicting changes in HU (Hounsfield units) with time to develop an index of perfusion. The images obtained were of satisfactory quality and differences between the underperfused and normal myocardium were made more prominent by using dipyridamole infusions.     

Multislice CT of the thorax: effects of contrast material pushed with saline solution using a dual power injector on contrast material dose and perivenous artifacts

A new method of power injection of contrast material flushed with saline solution for thoracic multislice CT using a dual power injector was evaluated in 105 patients. The patients were categorized into 3 groups of 35 patients each, according to the protocol of contrast material administration: (1) 100 mL of non-ionic contrast material(300 mgI/mL), (2) 75 mL of the same contrast material, and (3) 75 mL of the same contrast material flushed with 30 mL of saline solution. Scanning was performed in a caudal-to-cranial direction. Mean attenuation for the three protocols was measured in the superior vena cava, pulmonary trunk, ascending aorta, and descending aorta. Vascular opacification and perivenous artifacts were graded using four-point scoring by a consensus panel of three blinded radiologists. Intravenous injection of 75 mL of contrast material flushed with saline solution provided significantly better vascular opacification in the superior vena cava(p < 0.001) and pulmonary trunk(p < 0.02) than that provided by a 75 mL or 100 mL injection of contrast material alone. A similar degree of enhancement was observed in the ascending and descending aorta. Further, perivenous artifacts in the subclavian vein were significantly reduced (p < 0.05).     

Dynamic incremental computed tomography of the pulmonary hila using a flow-rate injector

Dynamic incremental CT of the pulmonary hila using a flow-rate injector is a safe, reliable, and reproducible technique. The technique described allows confident distinction of hilar masses from hilar vessels, while limiting the total amount of contrast medium used and eliminating radiation exposure to the radiologist.     

SENSE技术在磁共振腹部动态增强血管成像中的应用

目的：探讨磁共振敏感编码技术在腹部动态增强血管成像(DcE—MRA)中的应用优势。方法：将疑有腹部血管疾病的40例患者分为二组,实验组20例使用SENSE技术扫描;另外20例为对照组,直接行DCE—MRA扫描。结果：对照组20例中,13例因患者呼吸配合好,图像清晰,其中5例显示了动、静脉不同时相,8例由于扫描时间长,得到动、静脉均显影的图像。其余7例因屏气配合不好,图像出现伪影,为诊断带来了困难。实验组20例患者由于扫描时间明显缩短,均获得了清晰且不同时相的图像。结论：sENsE技术的使用大大地缩短了扫描时间,使腹部DCE—MRA可不受呼吸影响,并能获得不同时相血管强化图像,明显改善了DcE—MRA影像的质量,提高了诊断准确性。     

Use of a saline chaser in abdominal computed tomography: a systematic review

PurposeTo perform a systematic review of the literature regarding the use of a saline chaser in abdominal computed tomography (CT).Materials and methodsThe MEDLINE database was searched from 1966 to March 2007. Studies were included if they compared the magnitude of contrast enhancement with and without a saline chaser in CT and reported CT contrast enhancement values of the liver, portal vein, or abdominal aorta. For randomized controlled trials (RCTs) comparing the same dose of contrast material with and without a saline chaser, mean differences in the magnitude of contrast enhancement were pooled by using a fixed-effects model.ResultsSeventeen studies met the inclusion criteria. Three RCTs using clinical images were included in the meta-analysis. The mean differences in contrast enhancement of the liver, portal vein, and aorta were ?0.4 (95% CI, ?2.4 to 1.7), 7.4 (95% CI, 1.3 to 14), and 11 (95% CI, -5.3 to 27), respectively. Three RCTs using a time–density analysis were included in the meta-analysis. The mean differences in peak contrast enhancement of the liver, portal vein, and aorta were 8.2 (95% CI, 4.2 to 12), 28 (95% CI, 16 to 40), and 15 (95% CI, 0.3 to 30), respectively.ConclusionIn clinical images, a saline chaser did not improve contrast enhancement of the liver. In time-density analysis, however, a saline chaser improved peak contrast enhancement of the liver.