Tag Archives: imaging

Complications, Imaging

Best Of EAST #8: Timing Of Reimaging For BCVI

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There are still many questions regarding optimal management of blunt carotid and vertebral arterial injury (BCVI). We know that they may ultimately result in a stroke. And we kind of know how to manage them to try to avoid this. We also know that the grade may change over time, and many vascular surgeons recommend re-imaging at some point.

But when? There are still many questions. A multi-center trial has been collecting observational data on this issue since 2018. The group reviewed three years of data to examine imaging characteristics and stroke rate during the study period.

Here are the factoids:

  • A total of 739 cases were identified at 16 trauma centers
  • The median number of imaging studies was 2, with a range of 1-9 (!). Two thirds received only one study.
  • Injury grade distribution was as follows:
    • Grade 1 – 42%
    • Grade 2 – 30%
    • Grade 3 – 10%
    • Grade 4 – 18%
    • Grade 5 – <1%
  • About 30% changed in grade during the hospitalization, with 7% increasing and 24% decreasing.
  • Average time to change in grade was 7 days
  • Nearly 75% of those that decreased actually resolved. All of the grade 1 lesions resolved.
  • Stroke tended to occur after about one day after admission, although the grade 1 lesions took longer at 4 days
  • Strokes occurred much earlier than grade change

The authors concluded that there should be further investigation about the utility of serial imaging for stroke prevention.

Bottom line: This is basically a “how we did it” study to tease out data on imaging and stroke after BCVI. It’s clear that there is no consensus across trauma centers regarding if and when repeat imaging is done. And it’s not really possible to make any recommendations about repeat imaging based on this study.

However, it does uncover one important fact. It takes a week for the injury grade on CT to change, but strokes occur much earlier and usually within 24 hours! This is important because it makes it clear that it’s crucial to actually make the diagnosis early. Average stroke occurrence was 9% overall. Grade 1 injuries had only a 3% rate, but grades 2-4 were in the 12-15% range. Grade 5 had a 50% stroke rate!

These facts reinforce the importance of identifying as many of these BCVI as possible during the initial evaluation. The abstract I reviewed yesterday confirmed that the existing screening criteria (Memphis, Denver) will miss too many. More liberal imaging is probably indicated. If you missed the post, click here to view it in a new window.

Here are my comments for the authors and presenter:

  • The “change in BCVI grade over time” charts in the abstract are not readable. Please provide clear images during your presentation and explain what they mean. I was confused!
  • Based on your data, do you have any recommendations regarding the utility of re-imaging? Is it necessary in the same hospitalization at all? These patients will receive treatment anyway, and it doesn’t appear to have any impact on stroke rate.
  • Do you have any recommendations regarding the (f)utility of existing screening systems given the early occurrences of stroke in the study? Are you a fan of using energy / mechanism rather than a bullet list of criteria?

This is important work and I can’t wait to look at the data up close.

Reference: BLUNT CEREBROVASCULAR INJURIES: TIMING OF CHANGES TO INJURY GRADE AND STROKE FORMATION ON SERIAL IMAGING FROM AN EAST MULTI-INSTITUTIONAL TRIAL. EAST 35th ASA, oral abstract #34.

Head

The Second Head CT In Patients Taking DOACs

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Direct oral anticoagulant drugs (DOACs) are here to stay. When they were first released, I was very concerned with our inability to reverse them. I feared that we would have a rash of our elders presenting with severe head bleeds that we could do nothing about.

Well, that has not materialized. In fact, it appears that the probability of serious bleeding is more likely with our old reversible workhorse drug, warfarin.

But we are still spooked by DOACs. Nearly every center that has a practice guideline for managing patients with TBI on blood thinners includes a repeat CT scan after a given time interval. This is typically 6, 12, or even 24 hours.

Given the evolving safety profile of DOACs, is this even necessary? The surgical group at the Henry Ford Wyandotte Hospital in Michigan performed a retrospective registry review for their Level III trauma center. They reviewed the data for all adult patients who had suspected or confirmed blunt head trauma (any mechanism), were taking a DOAC, and received at least one CT scan.

Here are the factoids:

  • There were 400 patients with 498 encounters (yes, 15% came back with another TBI)
  • Patients were elderly (mean age 76) and nearly evenly split by sex
  • Fall was the most common mechanism (97%)
  • The first scan was negative in 96% of patients;12% of them did not have a repeat scan
  • Of the 420 patients who had a second scan, 418 were negative (99.5%). The two with positive scans were discharged uneventfully.
  • There were no differences based on specific DOAC, presenting GCS or mechanism

Bottom line: This is a relatively small, single institution study. However, it does appear that the authors have a large population of elderly patients suffering falls. This paper suggests that, indeed, a second scan may not be necessary. This parallels data from my own hospital. But to be on the safe side, keep an eye out for bigger, multi-institutional studies to be sure.

Reference: The utility of a second head CT scan af-ter a negative initial CT scan in head trauma patients on new direct oral anticoagulants (DOACs). Injury, article in press, June 13, 2021.

Imaging

Arms Up or Arms Down In Torso CT Scans?

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CT scan is a valuable tool for initial screening and diagnosis of trauma patients. However, more attention is being paid to radiation exposure and dosing. Besides selecting patients carefully and striving for ALARA radiation dosing (as low as reasonably achievable) by adjusting technique, what else can be done? Obviously, shielding parts of the body that do not need imaging is simple and effective. But what about simply changing body position?

One simple item to consider is arm positioning in torso scanning. There are no consistent recommendations for use in trauma scanning. Patients with arm and shoulder injuries generally keep the affected upper extremity at their side. Radiologists prefer to have the arms up if possible to reduce scatter and provide clearer imaging.

Radiation physics research has examined arm positioning and its effect on radiation dose. A retrospective review of 690 patients used dose information computed by the CT software and displayed on the console. Radiation exposure was estimated using this data and was stratified by arm positioning. Even though there are some issues with study design, the results were impressive.

The dose results were as follows:

  • Both arms up: 19.2 mSv (p<0.0000001)
  • Left arm up: 22.5 mSv
  • Right arm up: 23.5 mSv
  • Arms down: 24.7 mSv

Bottom line: Do everything you can to reduce radiation exposure:

  1. Be selective with your imaging. Do you really need it?
  2. Work with your radiologists and physicists to use techniques that reduce dose yet retain image quality
  3. Shield everything that’s not being imaged.
  4. Think hard about getting CT scans in children
  5. Raise both arms up during torso scanning unless injuries preclude it.

Reference: Influence of arm positioning on radiation dose for whole body computed tomography in trauma patients. J Trauma 70(4):900-905, 2011.

Philosophy

If A Tree Falls In A Forest…

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It’s time for a little philosophy today. There seem to be two camps in the world of initial diagnostic testing for trauma: selective scanning vs pan-scanning. I admit that I am one of the former. Yes, the more tests you do, the more things you will find, and this will make your radiologist happy. Some of these findings will be red herrings. Some may be true positives, but are they important? Here’s the key question:

“If a tree falls in a forest and no one is around, does it make a sound?”

Huh? How does this answer my question? Well, there is a clinical corollary to this question in the field of trauma:

“If an injury exists but no one diagnoses it, does it make a difference (if there would be no change in treatment)?”

Here’s an example. On occasion, my colleagues want to order diagnostic studies that won’t make any clinical difference, in my opinion. A prime example is getting a chest CT after a simple blunt assault. A plain chest xray is routine, and if injuries are seen or the physical exam points to certain diagnoses, appropriate interventions should be taken. But adding a chest CT does not help. Nothing more than the usual pain management, pulmonary toilet, and an occasional chest tube will be needed, and those can be determined without the CT.

Trauma professionals need to realize that we don’t need to know absolutely every diagnosis that a patient has. Ones that need no treatment are of academic interest only, and can lead to accidental injury if we look for them too hard (radiation exposure, contrast reaction, extravasation into soft tissues to name a few). This is how we get started on the path to “defensive medicine.”

Bottom line: Think hard about every test you order. Consider what you are looking for, what you might find, and if it will change your management in any way. If it could, go ahead. But always consider the benefits versus the potential risks, or what I call the “juice to squeeze ratio.”

References:

  • George Berkeley, A Treatise Concerning the Principles of Human Knowledge, 1734, section 45.
  • paraphrased by William Fossett, Natural States, 1754.
Imaging

The Cost Of Duplicate Radiographic Studies

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Speaking of radiation, here’s another tidbit. Duplicate radiographic studies are a continuing issue for trauma professionals, particularly after transfer from a smaller hospital to a trauma center. The incidence has been estimated anywhere from 25% to 60% of patients. A lot has been written about the radiation dangers, but what about cost?

A Level II trauma center reviewed their experience with duplicate studies in orthopedic transfer patients retrospectively over a one year period. They looked at the usual demographics, but also included payor, cost information, and reason for repeat imaging. Radiation dose information was also collected.

Here are the factoids:

  • 513 patients were accepted from 36 referring hospitals
  • 48% had at least one study repeated, 256 CT scans and 161 conventional imaging studies
  • Older patients and patients with low GCS were much more likely to receive repeat studies
  • There were no association with the size of the referring hospital or the ability of the patient to pay
  • Most transfers had commercial insurance; only 11% had Medicaid and 17% were uninsured
  • Additional radiation from repeat scans was 8 mSv. The average radiation dose from both hospitals was 38 mSv. This is 13 years of background radiation exposure!
  • The cost of all the repeat studies was over $96,000

Bottom line: This is an eye-opening study, particularly regarding how often repeat imaging is needed, how much additional radiation is delivered, and now, the cost. And remember that these are orthopedic patients, many of whom had isolated bony injuries. I would expect that patients with multiple and multi-system injuries would require more repeat imaging and waste even more money. It is imperative that all centers that receive transfers look at adopting some kind of electronic data transfer for imaging, be it a VPN or some cloud-based service. With the implementation of the Orange Book by the American College of Surgeons, Level I and II centers will receive a deficiency if they do not have some reliable mechanism for this.

“Level I and II facilities must have a mechanism in place to view radiographic imaging from referring hospitals within their catchment area (CD 11–42).”

Reference: Clinical and Economic Impact of Duplicated Radiographic Studies in Trauma Patients Transferred to a Regional Trauma Center. J Ortho Trauma 29(7):e214-e218, 2015.