Current Clinical Concerns in CT: Results : IV Contrast Administration
Gadolinium and CT
1. We have some experience studying CT and MR at the same day at our site. We have noted that Gadolinium appears at CT images. I don't know any paper or article about it, but if you are interested, I can send you some images showing this.
| Answer: We have seen similar findings with contrast in the renal pelvis on "non-contrast" scans. |
2. My group is receiving requests to allow certain oncology patients to undergo contrast-enhanced CT and MRI (different body parts) on the same day for convenience. I'm told that other groups have been doing this without complication. If the patient's renal function is normal, is there any problem with this situation. Does it matter which order the exams are done? (I would think MRI, then CT).
| Answer: In the patient with normal renal function, this should not be an issue. I agree that I would do the MR first and then the CT, but I doubt if this would make a significant difference. I also have not seen this addressed in the literature. |
3. Could you please give info on gadolinium use (doses) in CT for patients with creatinine levels?
| Answer: We do not use it. Although conceptually it might be useful, the studies are suboptimal. |
4. Lately many physicians are ordering CT studies using gadolinium. I was wondering what the benefits of using gadolinium are, and what the proper dosing is.
| Answer: We do not use it. Although conceptually it might be useful, the studies are suboptimal. |
References
Nyman U, Elmstahl B, Leander P, Nilsson M, Golman K and Almen T. Are gadolinium-based contrast media really safer than iodinated media for digital subtraction angiography in patients with azotemia? Radiology 2002; 223: 311-318.
- Summary: This viewpoint article advises against the use of gadolinium for DSA. The authors report that the gadolinium dose required for adequate attenuation at DSA may be 6 to 25 times more toxic than that required to produce adequate attenuation with iodinated contrast.
Wicky S, Greenfield A, Fan C-M et al. Aortoiliac Gadolinium-enhanced CT Angiography: Improved Results with a 16-Detector Row Scanner Compared with a Four-Detector Row Scanner J. Vasc. Interv. Radiol., Sep 2004; 15: 947 - 954.
- Summary: This study compared 4 slice and 16 slice MDCT using gadolinium as a contrast agent, to evaluate aorta, iliac and femoral arteries. Ten patients underwent 16 slice MDCT. The indication for gadolinium was either creatinine > 2.5 (N=8) or iodinated contrast allergy (N=2). The gadolinium dose was .3 to .4 mmol/kg (60 mL), infused at 3.5 mL/second, followed by a 40 mL saline flush. Compared to 4 slice MDCT, the 16 slice resulted in significantly higher enhancement of greater consistency. However, mean enhancement (post contrast density-precontrast density) using 16 slice MDCT was 82 HU in the proximal aorta, gradually decreasing to 74 HU in the common femoral artery.