Our experience at UW Medicine Radiology mirrors that of the authors in this article. DECT image quality is very much better with the current reconstruction software. It now rivals SECT in image quality and is the same in radiation dose. But tissue characterization is better and iodine contrast is much brighter – you may need much less injected contrast (up to 70% less).
This article illustrates two key points:
- CT information is particularly impactful in the ER environment where they need correct diagnoses quickly in order to initiate therapy and triage patients safely from crowded facilities.
- Dual energy CT provides incremental diagnostic information in the ER setting but without any incremental radiation dose – so using it routinely for certain indications may be effective.
“Don’t Skip the CTA” that’s the word going out to patients with advanced renal failure based on findings of researchers in Baltimore. In a study presented at June’s International Society for Computed Tomography (ISCT), Dr. Barry Daly demonstrated how CTA using moderate doses of IV contrast negatively affects only a small percentage of patients and provides valuable information that outweighs the chance of adverse effects.
However, because lower dose is better for patients, especially that small portion at risk with normal doses, Daly and his team also did a study of low-kVp, low-contrast-dose CTA in chronic renal failure patients. This technique is possible due to the advances in CT technology that have allowed radiologists the ability to get more out of smaller amounts of iodine.
While the low kVp techniques enabled much lower doses of iodinated contrast and resulted in images that looked great, the dual-energy CT technique may have accomplished this effect even better!
With dual-energy, you get the best of both worlds. You get the benefit of lower kVp effect (kEv in GE units), plus the ability to look at images which are equivalent to 100 or 120 kVp from the same CT raw data. Essentially, you still achieve substantial iodine dose reduction, but also get very dense HU enhancements in vessels and organs.
The bottom line is this: CTA isn’t something that patients with advanced renal failure should think about skipping. There is a too big a risk for going into surgery without one. The key is finding the safest technique to reduce the dosage level of iodinated contrast while getting the best images. Dual-energy CT may be the best solution out there.
RSNA (Radiological Society of North America) is the largest annual trade show in the world, with about 55,000 people in attendance for the 6 day event in Chicago, Illinois. The expo includes a large number of presentations and courses on science and modern radiology.
RSNA 2011’s two main themes were lower radiation dose in diagnostic radiology imaging (especially CT) and new technology. For lower dose, there was much material on tailoring a CT scan exactly to an individual patient – based on their body size, their cardiac output, their disease process, or the type of diagnostic challenge. Additionally, a lot about new iterative reconstructions in CT – both statistical and model based, was presented. Either method lowers dose a lot, but model based results in lowered radiation exposure by up to 80%.
New technology presentations and courses covered a range of topics including dual energy CT for better tissue characterization, and the combination of imaging modalities in one platform – like SPECT/CT, or PET/MR. These combined modalities may provide a better combination of disease identification plus precise localization.
In all, RSNA 2011 offered great insights and interesting presentations. Did you attend? Share your thoughts below!
A recent presentation at the 2011 International Society for Computer Topography (ISCT) meeting in San Francisco highlighted the effectiveness of using dual- energy CT for abdominal imaging. This CT- technique has become more promising for uncovering certain pathology that has otherwise been hidden by traditional diagnostic imaging procedures.
Dual- energy CT- by whatever technology – can be configured to employ less radiation than single energy CT. But for some specific applications, it produces more diagnostic and specific information. Dual- energy CT currently may be the best radiology technique for characterizing urinary tract stones to their chemical composition (which determines whether medical, shockwave, or laser therapy will be required), characterizing small renal masses, and characterizing liver masses into cyst versus tumor.
Additionally, dual- energy CT may apply to better detecting minimal liver tumors, lowering the amount of iodine needed for CT angiograms, and creating virtual non- contrast scans. The latter may reduce the overall CT radiation dose of a multi- phase study by 20 to 50 percent!
While dual- energy is still relatively new to the field, it is clear that it is a promising technique for CT dose reduction, while maintaining imaging quality. Further research and testing will be conclusive of the absolute benefits of dual- energy CT.