CT scan pilot for better donor screening
Does a CT scan contribute to better donor screening in preparation for organ donation? The initial experiences from a pilot by the NTS are positive.
2 februari 2024
Background
The CT scan pilot started in early 2023. In this pilot, a CT scan of the thorax and abdomen is performed on deceased donors in preparation for organ donation. This CT scan replaces the usual ultrasound and X-ray.Kinita Chotkan is a physician-researcher at the Dutch Transplant Foundation (NTS). She talks about the initial positive experiences with the new approach.
Example in other countries
The idea of performing a CT scan in preparation for organ donation did not just come out of thin air. This is already standard practice in France and all Scandinavian countries. Kinita Chotkan discovered this during her doctoral research into post-mortem organ donor quality and the optimal method of organ donor screening. The evaluation of the CT scan pilot is part of her doctoral research.
Great variation in organ anatomy
Kinita Chotkan: 'In the Netherlands, we currently do this according to the standard with an ultrasound and X-ray. But we knew there was a strong need among retrieval surgeons in the Netherlands to start doing this with a CT scan as well. Their main reason is that there is quite a lot of variation in the anatomy of organs being retrieved. They want to be prepared for that to prevent retrieval damage. That variation is more visible on a CT scan than on an ultrasound, the current standard method.'
“The variation in organ anatomy is more visible on a CT scan”
Undiagnosed malignancy
'Another reason is that patients are getting older. This increases the chance that donors have an undiagnosed malignancy. 'Fortunately, those numbers are small, but it is very unpleasant if it only becomes apparent during a retrieval procedure that the donor has a tumor. You would rather have such information about the donor at an earlier stage, before the retrieval procedure is started,' says Chotkan.
Customized donor organ
A third advantage of the CT scan is that the size of the donor organ can be better estimated based on it. Especially for the liver, it is important that the size matches the recipient. Both a liver that is too large or too small can cause problems, during the transplant, but also afterwards.
Size also matters for the lungs, although it is more difficult to determine the size based on the scan, because specific software is actually needed to measure lung volume. Finally, the quality of the donor organ can be assessed to a certain extent with the CT scan. For example, it can be seen whether there is scar tissue, inflammation, or severe atherosclerosis.
Dr. Dries Braat, transplant surgeon at LUMC: ‘For retrieval surgeons, performing a CT scan is a major step forward.’
Within our professional group, there has long been a desire to perform a CT scan before retrieving donor organs. It is actually very strange that a CT scan is performed for almost every major surgery these days, but that this is not standard before a retrieval procedure—a very extensive abdominal and thoracic surgery. We consider that a major shortcoming, because it can have advantages to know what we will encounter before the procedure.'
'We regularly see that the anatomy of donor organs, and especially the blood vessels, is different. For example, a kidney can have multiple arteries instead of one, and the blood supply to the liver and pancreas can also be abnormal. If you know that in advance, the chance is smaller that you will accidentally damage the vessels or the organ during the retrieval procedure. Even if the anatomy is normal, it is valuable to have information about, for example, the degree of vascular calcification, the size of the organs, and the presence of any tumors.'
'For us as retrieval surgeons, performing a CT scan is therefore really a big step forward. In my view, the costs are not a limiting factor. These form only a fraction of the total costs of the entire donation process. It can even be cost-efficient if the loss of an otherwise good organ can be prevented.'
Does the new approach have only advantages?
‘This method makes organ donation safer, but there is also a downside,’ Chotkan qualifies. ‘Because you screen more extensively, you also encounter more abnormalities. Some of these are clearly benign or malignant, but there are also borderline cases. For example, nodules in the lungs; small spots that could be an early stage of lung cancer. Usually, a biopsy is taken during the retrieval procedure, and a slice—a so-called frozen section—is examined by a pathologist. This allows for a quick diagnosis during surgery.’
‘In the case of a benign abnormality, the retrieval can simply continue, but if it is malignant, it must be determined in consultation with the transplant center whether they still accept the organ. This process takes extra time, which is naturally inconvenient. However, if you know in advance, you can organize the logistics accordingly, for example by ensuring the pathologist is on standby, preferably in the operating room.’
“More extensive screening also leads to finding more abnormalities.”
Possible adverse effects of contrast agent
Another potential disadvantage is that contrast agent is sometimes used for the CT scan, which can potentially be harmful to the kidneys.
Prof. Dr. Luuk Hilbrands, nephrologist at Radboudumc and involved in the pilot project, explains: ‘Initially, I had some doubts about introducing the CT scan. My colleagues within the National Kidney Transplantation Consultation (LONT) were also somewhat skeptical. Therefore, based on existing data, we investigated whether we saw a harmful effect from exposure to contrast agent in donors who had undergone a CT scan for another reason, compared to donors who had not. Fortunately, that turned out not to be the case. However, this was a retrospective study where the dose of contrast agent was unknown, so we are not entirely certain yet.’
Positive experiences
Kinita Chotkan is analyzing the first 100 procedures within the pilot to see if there is truly no difference in transplant outcomes due to exposure to contrast agent.
‘We feared logistical problems for the people working in the intensive care unit (ICU). They move the donor from the ICU to the radiology department. Fortunately, the extra work has so far not been a reason not to perform the CT scans. Organ donation coordinators (ODCs) have also been positive so far.’
How does the evaluation take place?
After each donation procedure, Kinita Chotkan sends the ODC an email with questions about how the procedure went, partly to check if there were any logistical problems.
‘Since June 2023, I have also been sending a questionnaire to the retrieval surgeons. This gives me an idea of whether the method provides an advantage. For example, whether the retrieval surgeons change their surgical strategy due to the CT scans. This information contributes to the argumentation for final implementation and reimbursement of the new working method.’
‘For now, everyone involved seems enthusiastic. At the end of the pilot, we will be able to definitively determine whether it is feasible to perform a CT scan on every donor and what the added value is for the donation process.’
Facts and figures of the first 10 months
Since the pilot began in January 2023 in the Groningen donation region, the project has been gradually expanded to other regions. Since January 1, 2024, all regions have been participating.
Up to and including October 2023, 115 CT scans were performed for organ donation procedures. These analyses show that this led to the initiation of 95 retrieval procedures and 90 donation procedures, in which at least one organ was transplanted.
In only one situation was it not possible to perform a CT scan. This was because the donor could not be moved to the radiology department, as intensive ventilation was required in the ICU. In this donor, an abdominal ultrasound was performed instead of a CT scan.
Furthermore, a frozen section was made and evaluated in the operating room 4 times following a finding on the CT scan. In all cases, it was a benign abnormality and the donation procedure could continue. It only happened once that a procedure was stopped in consultation with the family after a suspicious abnormality was found in the lungs on the scan.
Publications
After every donation procedure, Kinita Chotkan sends the organ donation coordinator Publications
Radiological Screening Methods in Deceased Organ Donation: An Overview of Guidelines Worldwide.
- Authors: Chotkan KA, Mensink JW, Pol RA, et al.
- Transpl Int 2022; 35: 10289.
- Read the publication
Transplant Outcomes After Exposure of Deceased Kidney Donors to Contrast Medium
- Authors: Chotkan KA, Hilbrands LB, Putter H, et al.
- Transplantation 2023. Online ahead of print.
- Read the publication
