Hi Michelle, Kimberly, Thi Thanh and everyone else,
Thank you so much for reaching out. I decided to answer in the group chat instead of individually since a couple of you reached out to me.
Yes, I used this great article (2016 SCCT guidelines for the performance and acquisition of CCTA...) to start redacting my protocol and it has helped me a lot but it is not scanner specific and most of the recommendations need to be individualized with the scanner to be used and that's were I am having problems with.
I have been working with a
Philips Brilliance 64 row detector and recently with a
Philips Ingenuity 128 row detector in another hospital. I believe the fastest gantry rotation time for Philips CTs is 0.4 sec as for temporal resolution, which I know is one of the most important things in cardiac imaging, so I know administering metoprolol is a most in order to get diagnostic images. We give metoprolol IV (up to 25 mg) to control HR, ideally get it to be 60 or so but I feel even with this HR I still get a lot of motion artifact. I recently sent an email to cardiologists as to please prescribe metoprolol for patients to take 12 h before exam as I read it helps a lot to achieve target HR the day of the exam (in there are no contraindications of course); hopefully this will work out.
Sometimes images are very noisy and I know we should increase mAs to improve noise, but is that something we do (me and technologist) or the scanner does that automatically? I have the same question for kVp; I know we should use higher kVp for big patients but how much more and above which BMI? Should I follow the standard recommendations or is this something that changes depending on the scanner? Also, does the scanner does this automatically or we have to manually change it?
How do I choose the contrast volume? I know this depends on several things (scan duration, body weight, injection rate). We use Optiray 350 and our CT techs give 125 ml for "normal/small" patients and 150 ml for obese patients, this is a standard they use for every CT exam, but I feel this is a lot and not sure if this is right. We have dual injectors.
We do bolus tracking with ROI in the DA. In the beginning we put ROI in the AA but attenuation was suboptimal so we changed to the DA to give contrast more time to travel and it worked. I am pretty sure we don't give saline although I know it is recommended to decrease streak artifact in the RA.
For TAVR exams we scan patient twice for heart CTA and then again for ab/pel CTA because scan is not fast enough with a 64 detector CT so we divide contrast in half and administer twice (maybe with the 128 we can scan once).
I know if HR is great (60 or less) we are supposed to do prospective EKG gating to decrease dose but so far every exam has been done retrospective. Is this something that the tech chooses or the scanner does this automatically? I am not even sure our cardiac package has capability for prospective triggering...is this possible?
As for image reconstruction and post processing, which slice thicknes should we use? smallest possible? is this something that the scanner/cardiac package selects automatically?
For nitro, recommendations are 0.4-0.8, should I give one tablet/spray or two?
I know this is a lot of information/questions but anything you can help me with and help me clarify I would be eternally grateful. I feel so grateful to have all of you smart ladies as a resource and for support!
Warm hug from Puerto Rico,
Camila
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Camila Saade MD
University of South Florida Program
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Original Message:
Sent: 08-05-2021 02:33
From: Michelle Williams
Subject: help!
Hi Camila
What CT scanners are you working with?
I found the SCCT acquisition and reporting guidelines really helpful when I was starting out even though they weren't scanner specific - https://scct.org/page/GuidelinesCriteria
thanks
michelle
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Dr Michelle Williams
University of Edinburgh
Original Message:
Sent: 08-04-2021 13:13
From: Camila Saade
Subject: help!
Hi everyone!
I am a cardiothoracic radiologist in San Juan, PR. I recently started working after finishing my cardiothoracic radiology fellowship and I am starting from zero cardiac imaging centers in PR. Even though I passed my SCCT boards (thankfully!) I feel I need some guidance establishing protocols individualized to the CT scanners and equipment we have available. If someone has the time and would be so nice and offer me some knowledge I would greatly appreciate it!
Thank you in advance,
Camila Saade