MDCT angiography of the pulmonary arteries: influence of iodine flow concentration on vessel attenuation and visualization

OBJECTIVE

Our objective was to assess the influence of iodine flow concentration on attenuation and visualization of the pulmonary arteries in thoracic MDCT angiography.

MATERIALS AND METHODS

One hundred consecutive patients who were referred to our department with suspected acute pulmonary embolism underwent MDCT angiography of the pulmonary arteries either with 120 mL of standard contrast medium (300 mg I/mL) (group A) or with 90 mL of high-concentration contrast medium (400 mg I/mL) (group B). The contrast medium was injected at a flow rate of 4 mL/sec. The scan delay was determined using a semiautomatic bolus-tracking system in all examinations conducted with the same scanning parameters. Quantitative analysis was performed by region-of-interest measurements along the z-axis to compare the attenuation profiles of the two groups. Attenuation of the fourth-, fifth-, and sixth-order arteries was assessed visually for differences between the two groups.

RESULTS

The mean enhancement along the z-axis was 268 +/- 56 H in group A and 344 +/- 108 in group B. The difference of 76 H was statistically significant (p < 0.001). The attenuation profile was similar in both groups. The detection rate of fifth- and sixth-order arteries was significantly higher in group B than in group A (94% compared with 91% and 72% compared with 60%, respectively, p < 0.01).

CONCLUSION

Use of a high flow concentration of iodine in MDCT angiography of the pulmonary arteries significantly increases attenuation of the pulmonary arteries, thereby improving visualization of subsegmental pulmonary arteries.

Frequency and Significance of Lumbar and Inferior Mesenteric Artery Perfusion After Endovascular Repair of Abdominal Aortic Aneurysms

PURPOSE

To evaluate the frequency and influence of perfused side branches (lumbar arteries [LA] and inferior mesenteric artery trunks) on development of type II endoleaks (EL-II) and on volume changes of abdominal aortic aneurysms (AAA) after endovascular repair.

METHODS

Of 114 patients undergoing EVR of AAA, 89 patients (83 men; mean age 72+/-7.5 years, range 51-88) with >6 months' follow-up and no type I endoleaks were retrospectively analyzed to determine any relationships between retrograde perfusion, endoleaks, and sac volume. Data were derived from computed tomographic angiographic (CTA) scans taken before and after intervention, at discharge, and at 1, 3, 6, and semi-annually thereafter in follow-up. Two groups were identified and compared based on their status at 6 months post EVR: without perfused side branches (group 1) and with perfused collaterals (group 2); group 2 was further divided according to the absence (2a) or presence (2b) of endoleak.

RESULTS

Median follow-up was 24 months (range 6-36). Based on a total of 582 CTAs analyzed, 17 (19%) patients developed type II endoleaks (EL-II) during follow-up. There was a significant difference in the number of perfused LAs prior to EVR between groups 1 (n=44) and the 45 patients with postprocedural patent collateral arteries in group 2 (p<0.05); there was no significant difference between groups 2a and 2b (p=0.88) relative to the number of pre-existing patent collaterals. The number of pLAs preoperatively and the rate of type II endoleak were significantly correlated (p<0.05). No type II endoleak was seen in patients without perfused side branches (p=0.01). No significant differences in mean volumes were found between groups 1 and 2a (no EL-II), but significant differences between groups 1 and 2b were seen in later follow-up.

CONCLUSIONS

A larger number of patent LAs before EVR was associated with a significantly higher rate of type II endoleak. Patent collateral vessels were common after aneurysm repair, but the frequency decreased during follow-up. Persistent side branch perfusion was associated with increased type II endoleak after endovascular AAA repair. Significant differences in volume changes in later follow-up were seen between patients with or without type II endoleak.

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.

Improvement of parenchymal and vascular enhancement using saline flush and power injection for multiple-detector-row abdominal CT

The aim of this study was to determine if a saline solution flush following low dose contrast material bolus improves parenchymal and vascular enhancement during abdominal multiple detector-row computed tomography (MDCT). Forty-one patients (24 men and 17 women; mean age 49 years, age range 27-86 years) underwent abdominal MDCT (collimation 4x5 mm, 15-mm table increment, reconstruction interval 5 mm, gantry rotation period 0.8 s) with a single- as well as with a double syringe power injector. Indication for examination were benign and malignant tumors and inflammatory diseases. Patients received 100 ml nonionic contrast material (300 mgI/ml) alone or pushed with 20 ml saline solution. Mean enhancement values for both protocols were measured in the liver, the spleen, the pancreas, the renal cortex, the portal vein, the inferior vena cava and the abdominal aorta. Double syringe power-injector protocol led to significantly higher parenchymal and vascular enhancement than single syringe power-injector protocol (p<0.05). The improvement in mean enhancement of the liver was 9 +/- 9 HU, of the spleen 8 +/- 10 HU, of the pancreas 7 +/- 9 HU, and of the renal cortex 8 +/- 20 HU. The improvement in mean enhancement of the portal vein was 10 +/- 17 HU of the inferior vena cava 8 +/- 13 HU and of the abdominal aorta 10 +/- 17 HU. The use of a double syringe power injector with saline flush following contrast material bolus significantly improves parenchymal and vascular enhancement during contrast-enhanced abdominal MDCT with low iodine doses.