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Very good website. The Dual source CT is new technology of CT. We are in Indonesia need experience from another country
Thorsten R. C. Johnson, M.D:
Thanks for your reply, I want to ask another question: If we want to get good images, how to scan for lung perfusion. For exam, we must use 4ml/s?5ml/s…… injecting speed? or we use 70ml?80ml…… contrast material ?can we change two tube~s kv and mas?
best wishes to you!
In our experience, 4 ml/s is the preferable injection rate to avoid beam hardening artifacts. 70-80 ml should be adequate for typical asian body habitus and weight. You should not change the kV settings (which is not possible anyway except for special research protocols). You may want to increase the mAs for very heavy patients, but the preset value should work fine in general.
we’ve done a DE KUB on 10 patients with a proven chemical analysis of one stone. however , if we cange the protocol from the default seimens, some results may be confusing. also i would like to know if any modification can be done so that tiny calculii (which otherwise are not characterised) could be characterised. would a smaller fov in the recon help??
Our experience shows that the reduction of the calculation range is helpful in the depiction of small urinary calculi. This parameter can be set on the advanced definition dialog card. In addition, the limits for calculation can be adjusted. This can be of interest when you examine stones with very low or very high attenuation values. So far – to my knowledge – there is no information on the optimal field of view. On the other hand, the slice acquisition plays an important role. For example Primak et al. showed that the accuracy in the determination of stone compositions depends on the collimation used with dual-source dual-energy CT.
can the DSCT identify the fibrous cap and distinct the various components in the plaque?
it was a pity ,just saw it
hi , i appreciated your delicated word in the field of ECG-edition,would you send the edited ECG chart of this case? thank you
The ECG edit has been the saving grace for a few of our challenging patients. The aberrant beat is easy, but the pesky pacemaker is not. I have found in attempting to clear the aberrant beat, the area of interest is easier to address than the entire dataset. Pick your battle. Delete a sync prior and reconstruct the segmeted area, post and try to change the temporal resolution to 145 ms or 165 ms over that area of fault. The pacemaker steps have kicked into play if the patient happens to drop below the dial down during the scan. Reviewing the ecg tracing, delete the sync on each of the pacer spikes, set a median TR, you might also try using the Best systolic phase if the heartrate still remains high after the count is adjusted. I have had what began as a horrible scan, become a motion free dataset with this technique.
Please, give me a advise, How to compare between CT perfusion and MR perfusion, which one is better than? thank you and best regards
Dear Anders Persson !
Then, in the furture, Can we be scan CTA without i.v.contrast (for clinical diagnostic) ?( it’s only in my mind ), I think that we could reformat on the VRT, something like this ( similar to your figure 4) but How is it on the MPR or 2D ?
By the way, please give a answer about DSA (for neuro)
all of the vendors (GE, Phillip, Siemens, Toshiba…) have had the DSA software also.
Thank you and best regards
Minh Truong
I thank you for your reply. As you know, the favourite topic by the compettition, is that the Dual Source CT has double the radiation!
I am surprised at how many Physicians are not aware of the difference between the DSCT and the Multislice CT for instance.
Could you perhaps take some time and explain the differences please?
Regards.
We have a record 175 bpm and achieved extraordinary images in a systolic recontruction. The DSCT scanner gives the the best systolic and diastolic phases in seconds and made a VSD apparent only by providing both these reconstructions to the radiologist. Amazing detail.
It is interesting case where most of cases that we are ignore to look for pulmonary veins.
But anyway, what the different or the advantages of use DSCT compare to MSCT?
i do believe that nothing much except of faster scan time.
what the best recommandation contrast flow rate selection.
is there any different if we use high flow rate(6ml/s and above).
how about contrast flow at the distal of arteries?
i just wonder, for this chest pain protocol, are you recommend to use test bolus or care bolus(monitoring technique).
For further information on the topic Dual Source CT and radiation dose, please see the following publications:
- Stolzmann P et al. Radiation dose estimates in dual-source computed tomography coronary angiography.
Eur Radiol. 2008 Mar;18(3):592-9.
- Leschka S et al. Low kilovoltage cardiac dual-source CT: attenuation, noise, and radiation dose.
Eur Radiol. 2008 Sep;18(9):1809-17.
- Stolzmann P et al. Dual-Source CT in Step-and-Shoot Mode: Noninvasive Coronary Angiography with Low Radiation Dose.
Radiology. 2008 Oct;249(1):71-80.
Kind regards
It is wise to increase contrast flow rate in difficult patients (e.g. patients with stents or obese patients). Of course, it is important not to run out of contrast towards the end of the scan. Duratio nof contrast injection therefore also needs to be increased to compensate for the higher flow rate.
Our policy at our institution is to inject contrast for the same duration as data acquisition will take, nbut to inject at least 10 seconds.
So, if the scan will take 12 seconds, we will inject 60 cc at a flow rate of 6ml/s or 72 cc at a flow rate of 6 cc/s
If the scan taes only 8 seconds, we inject for 10 seconds. 50 cc at a rate of 5cc/s or 6 cc at a rate of 6 cc/s.
We generally recommend bolus tracking in the aortic root for this application, because it does not require additional contrast and it is not affected by variability due to breathing, and the bolus geometry corresponds to the actual bolus. There is a specific paper addressing this matter: J Comput Assist Tomogr. 2007 Mar-Apr;31(2):265-71.
Regarding pulmonary veins without cardiac mode (retrospective ECG gating) DSCT system acquires the CT data with 64 slices and therefore there is no significant difference compared with a 64-slice MDCT.
the picture 1 is wrong.
why the right kidney seems more contrast enhanced then the left?
sincerely yours
ubachuster
very important study I was just searching for such information!
Thank You!
It is not for free? The article seems tobe interesting not only for AHA members. Where can i get it?
Good observation !!! Image 1 is indeed incorrect, this image should be a non-enhanced image and not an enhanced image a shown here, this needs to be corrected.
The conventional images are combination images of 80 kV and 140 kV (no color coding), using 70 % of the image information from the 140 kV tube and 30 % of the 80 kV tube. As 80 kV is very iodine sensitive, the net enhancement is greater inside the 80 kV field of view. A good example is the left kidney. The hilar region is within the 80kV fiel odf view, the rest not. The hilar part is more enhancing than the rest of the kidney that is outside the 80 kV field of view (compare with color coded image).
is there any documentation regarding the analysis of gallstones with dual energy?
Regarding DECT in the characterization of gallstones, there is not much work out there. There is some preliminary work and I have included an abstract from the RSNA 2006 please see below, hope this answers your question.
SESSION: Gastrointestinal (Dual Energy, Innovations)
Dual-source CT Characterization of Gallstones Using a Dual-Energy Analysis
DATE: Wednesday, November 29 2006
PURPOSE
Standard treatment for symptomatic and non-symptomatic cholecystolithiasis is cholecystectomy. Non-invasive approaches such as oral litholysis are mainly limited to patient with pure cholesterol stones, which often is difficult to assess when using either ultrasound or conventional CT. This study examines the possibility of a novel clinically available dual-source CT using two tubes mounted in the gantry applying dual energy technique to non-invasively characterize gallstones in vitro (DECT).
METHOD AND MATERIALS
Pathology provided 40 randomly selected gallstones excised during cholecystectomy. They were individually embedded in ultrasound gel. Scanner settings were: 2 x 64 slices per rotation, collimation 0.6 mm, tube 1: 80 kV, 175 mAs and tube 2: 140 kV, 170 mAs. Pitch 1.4, reconstruction slice with 1.0 mm, recon increment 1.0 mm. For comparison scans were repeated using the same scanner setting using monoenergetic scans at either 80 kV as well as 140 kV. Dual energy analysis was performed image based. Gold standard was pathological classification.
RESULTS
Pathological analysis revealed 7 calcified stones, 15 pigmented stones, 7 pure cholesterol stones 6 mixed cholesterol stones and 5 mixed pigmented stones. Dual energy analysis was able to distinctively differentiate between all subtypes. Moreover DECT was able to differentiate between two different subtypes of cholesterol. One subgroup had 4 cholesterol stones that were not visible in conventional 140kV monoenergetic CT and had a lesser density. Pathology differentiated these types by surface analysis. The non-visible group had a smooth surface whereas the other group had a structured surface. This other group was visible at both energy levels.
CONCLUSION
These primary results indicate that DECT permits subtle characterization of gallstones in vitro using a clinically available dual source CT. It also allows for detection of primarily non radio opaque cholesterol stones at 140kV, an energy level often used for obese patients.
CLINICAL RELEVANCE/APPLICATION
Reliable detection and characterization of cholesterol stones could permit better treatment decision for obese patients at elevated risk during surgery, whether to undergo oral litholysis or surgery.
To Johnson
Hello!
My name is Mi-Jin, Kang, Seoul National University Hospital, Korea.
Actually I presented educational exhibit of ‘thoracic application of dual energy CT’, at RSNA 2009.
And My presentation was received invitation of Radiographics.
If you don’t mind, I would like to use your figure 2 and 3, printed at Eur Radiol 2007;17:1510-1517.
I will wait for your answer, sincerely.
Thank you.
I agree with you Dr Suranyi, but I think with a minimal dose of the new technology and the quality of the images like aquired by the DSCT, there are enough evidence to replace the MIBI with the CTA, and even the core 64 study was negative because of the high threshold of the level of the stenosis(more than 50%), it showed that the cta may point the finger at the target vessel to treat,
on the other hand the ACCURACY trial had better result and was multi vendor study.
Thank you for your response. I may have failed to mention, the pediatrics that we scan have congenital anomalies and many have had step surgical interventions. The mapping of the anatomy is critical for the surgeon. In the interum, we have adapted a total 80/20 blend of contrast, using a lesser kVp is possible because of that. Injecting in a saphenous vein decreased the SVC contrast artifact possibility, so again allows a decrease radiation dose. Many of our peds have a HR in the 130-150 bpm range. A 3-4 second scan at most. Aain, I appreciate your response to my question.
Thanks for your interest. Of course I had to transfer the copyright of the article including its images to the publisher, i.e. Springer. According to their guidelines I think you have to give reference to the original article in the figure caption. Please refer to the Springer website to make sure you’re meeting their copyright requirements.
Dear Dr. Hadjadj,
Thank you for your reply to my earlier comment.
While I am similarly convinced that cardiac CT will (and should) be utilized more and more, it is important to bear in mind that even if we were able to perfectly visualize all coronary arteries and all segments, with the conventional CT methods we would still not be able to reliably quantify tissue perfusion.
For the assessment of myocardial perfusion, nuclear cardiac scans are considered the gold standard (even though some would argue they are more the “old standard”), and MRI is emerging to compete for becoming the modality of choice.
Newer methodologies, such as dual-energy cardiac CT, which was pioneered here at MUSC, attempting to assess the iodine content of the myocardium, and other efforts aimed at studying myocardial perfusion with CT even during adenosine stress may provide us with the technology in the future that allows us to reliably assess the severity of the coronary artery disease at the tissue level.
On the other hand, CT angiography has another important advantage over conventional angiography, which is the ability to visualize coronary artery plaques. To identify lesions with a high potential of becoming culprit lesions in acute coronary syndromes, it is crucial to differentiate calcified plaques from noncalcified (fibrous and lipid rich) plaques. This is definitely one strength of coronary CTA, with which none of the other modalities can compete with.
Thank you for your continued interest in our website and in promoting cardiac CT. We are looking forward to hearing from you again.
Best regards,
Pal Suranyi , MD, PhD
Dear Colleague,
Could you please inform us about the usage contrast media in coronary CTA for Philips Brilliance (64-slice)?
Sincerely,
Dr.Ersin Ozturk
the advanced of DSCT
Dear User
The injection protocols for contrast agent do not vary significantly between different scanners. We currently recommend the following:
Use a flow rate of 5 ml/s. In difficult patients, such as obese patients or patients with stents or known severe calcification, increase to 6 ml/s or even 7 ml/s.
Inject for the same duration as the scan. If the daza acquisition will last 12 seconds, inject for 12 seconds. If it lasts 16 seconds, inject for 16 seconds.
Always inject for at least 10 seconds. If your data acquisition is shorter than 10 seconds (i.e. 6 seconds), still inject for 10 seconds.
Add 4 seconds if you use a bolus tracking approach. Do not add anything is you use a test bolus approach. If you use a test bolus, start your scan with a delay that is 2 seconds longer than the contrast agent transit time that you measured.
Follow your contrast injection with 60 ml of saline or 60 ml of a mixture 20% contrast/80% saline, at a flow rate of 5 ml/s.
If you do a test bolus approach, us 10 ml of contrast agent at 5 ml/s and follow by 60 ml of saline at 5 ml/s.
I wish you success with your scanning
Stephan Achenbach
Excellent visualization and clinical workup, shows the awesome technology and diagnostic care available.
Dear Sirs,
Where can I find the basic algoritms to compute dual enegy images made with DR (flat panel detectors) ?
Does anyone knows if specific Z-images (specific atom number) can be obtained in that way ?
Thanks in advance,
Francis Cuigniez
MD. radiologist.
The field of DR (digital radiography) works with projection images. In cross-sectional Dual Energy modalities like Dual Source CT it is possible to reconstruct effective z and rho values (atom number and electron density) based on the photo effect and the absolute density in the individual image voxel. However, this is not possible or would make little sense in projection images, because the individual image pixel contains a sum of several different structures. It is possible to vary the weighting of photon energy in these DR images to produce “soft and hard” images to accentuate soft tissue or calcified structures, e.g. to identify and differentiate lung nodules or coronary calcifications. Still, from my perspective the summarized effective z value of a pixel in the projection image would not convey more information than that, even if one tried to quantify it. I can recommend the July 2003 issue of the Journal of Thoracic Imaging which gives quite a wide overview of available techniques and diagnostic performance of DR.
Best regards,
Dr. Thorsten Johnson
I was reading up on the CT Siemens Daul Souce Technology and was quite impressed. I am actually a Toshiba fan and believe their 320 slice scanner is as good as it gets. So what scanner is best for brain perfusion and cardiac imaging. Dual Source vs 320 Slice
Dr. Stephan Achenbach, M.D.
I agree with the injections protocols you describe; at our insitution we have a GE equipment of 64 channels, and we use the amount of contrast and its flow depending the weight of the patient, for example : 70 kg we use 85 to 90 cc at 5.5 to 6 ml/sec of flow rate. We use two flows of contrast, the first flow is 5.5 ml/sec using 55 cc and the second flow is 6 ml/sec using 45 cc following of 30 ml of saline at 6 ml/s. The purpose of this technique is to visualize the distal arteries of the heart and we obtained very good results.
And we needed to know the limits of the flow of the contrast, and you described before we can use 6 or 7 ml/s in obese and stent cases.
Thank you for your instructions and recommendations.
Thank you for your interest in the DSCT community.
Regarding your question on brain perfusion, I cannot really give you a good answer because of no experience in this body region.
In regard to cardiac imaging, I certainly can recommend the dual-source CT technology. It has proven more accurate at lower heart rates than 64-slice CT, it is – to my knowledge – the only scanner that is able to scan hearts in an accurate fashion also at higher heart rates, and finally, it must be considered very dose efficient. With a standard retrospective spiral protocol that is required in patients with high and/or irregular heart rates, you will end up with around 7-9 mSv. When you use a standard step-and-shoot protocol at 2-4 mSv (which can be used in patients with heart rates below 70 bpm), and when using the recently introduced Flash- (or high pitch) mode, you end up at a dose below 1 mSv for a coronary CT angiography examination.
I have no experience with the 320-slice CT scanner for cardiac imaging. So the only thing I can recommend is to review the (sparse) literature. Here you can see that the lowest reported radiation dose of a cardiac CT using this scanner is around 5 mSv (when using a protocol that requires lowering the heart rate with beta-blockers).
Best regards and good luck with your scanner choice.
Hatem Alkadhi
sir,
i am too working on a dual source siemens scanner and have done a lot of coronart angios with conventional step and shoot method and in most of the cases end up with radiation dose of 2 – 3mSV (including the calcium score). most of the times i do calcium scan with 80 KV and coronary angios with 100kv depending mainly on chest circumference and BMI.But have not yet tried reducing the effective mAS a lot since i do scans with care dose 4D on mAS will be selected automatically.if i do reduce mAS are there any standards so that the images will be not very noisy.
Hello-
perhaps this is a premature question, but are the billing codes for Siemans Somatom different from those of traditional C/Ts? One would think the reimbursement for this new modality would warrant seperate CPT codes. I have searched both the 2101 CPT book and Siemans website to no avail and thought perhaps someone @ DSCT may have the answer?
Dear User,
in order to give an satisfying answer it is necessary to know which country you are working in. Billing codes differ in every country and thus health care system. Speaking for Germany billing codes unfortunatley do not represent technical advances very well.
With best regards
Marco Das
Could I please know the field of view for the two tubes for COW and craniocervical angiograms?
Regards
Amogh
Dear Sandra, I have been practicing Cardiac Imaging on 64 Slice MDCT. We had similar case recently and found these videos and images useful as reference. I would like to thank you for this Excellent useful blogs.
This is my first visit to dsct.com. Looks fantastic site with so many bloggers. I would recommend you to visit my another radiology blog website – http://www.iradix.in/Blogs.html
Here you would find more than 150 blogs on various radiology issues. All are worth reading!
I wanted to add my question to the above question about Dual Energy CT Scans. I am also looking for any additional CPT codes that would be used for this type of exam. Our facility is located in Pittsburgh, Pennsylvania, USA.
Thank You,
Kim Pavlic
Very impressive… super images… fantastic technology… Thank you ver much.
The CTDI value written here is 6,33 mGy, how small dose I think. how can it be, can you tell me? because most of CT examinations in my country resulting CTDI about 50’s mGy
This case demonstrates the considerable dose savings of prospective ECG gating acquisition and 100 kV tube currents. These dsoe savings have beeen well documented in several recent publications involving the Definition scanner-thank you, Chip Gilkeson
Dr. Bauer-
For your lung and abdomen scans you recommend using CareDose4D and various mAs settings. Does this refer to the quality reference mAs?
Thanks,
Robert
Yes, these values do refer to the quality reference mAs.
as a trainer in ct background needs more information to sent about dual source
ct .
best regard
Dear dr Johnson,
Can you tell me what the HU are of the coronary and pulmonary tree? Did you find that optimal for evalutating both the coronaries and pulmonary arteries? Kind regards, Marc Kock
What is the efficiency of each anode material and is made up?
Thanks for your interest. I had anonymized the image when exporting it, so I cannot tell you the actual values of that dataset. But we are acquiring TRO scans quite frequently these days, and one of today which I am just reading has between 500 and 600 HU in both the pulmonary and coronary arteries, which is certainly sufficient. If you are specifically interested in bolus optimization for this purpose, you may want to have a look at a study I performed on this (Optimization of contrast material administration for electrocardiogram-gated computed tomographic angiography of the chest. Johnson TR, Nikolaou K, Wintersperger BJ, Fink C, Rist C, Leber AW, Knez A, Reiser MF, Becker CR. J Comput Assist Tomogr. 2007 Mar-Apr;31(2):265-71.).
De Dual Source CT experts community… Sjiek hoor!