Category Archives: Imaging

Do We Need Cervical MRI Scans If The CT Is Negative?

The debate on how to clear the cervical spine just never ends. We have finally come to some degree of agreement that certain patients (awake, alert, not impaired or head injured, without distracting injury) can undergo clinical clearance alone.

But if those criteria are not met, what next? Universally, adults receive a CT scan of the cervical spine. In the majority of centers, this is coupled with a good clinical examination. And if both are negative, the collar can be removed.

But recent literature suggest that a good, high-quality cervical CT read by a skilled neuroradiologist may be good enough. This has been demonstrated in several papers involving patients who are comatose or other-wise unable to participate with a clinical exam.

Many centers and trauma professionals are still reluctant to remove the cervical collar without that clinical examination. A new study asked the question: would an MRI provide additional, significant information over and above the CT scan in those patients who could not be examined or had persistent neck pain?

A consortium of 8 Level I and II trauma centers in New England participated in this study coordinated by Yale. Blunt trauma patients who underwent MRI after negative cervical CT were considered for the study. On further review, if they received the scan because they could not be clinically evaluated, or if they had complaints of persistent neck pain, they were enrolled. CT scanners with at least 64-slice capabilities were required. There was no mention of the qualifications or special experience of the radiologists reading the images at each center.

Here are the factoids:

  • 767 patients were enrolled in this 30-month study. A total of 43% were for persistent neck pain, 44% for inability to examine, and 9% for both.
  • Nearly a quarter had an abnormal MRI scan:
    • 17% ligamentous injury
    • 4% soft tissue swelling
    • 1% disk injury
    • 1% dural hematoma
  • The collar was removed in most (88%) patients with a normal MRI, but in only 13% with ab-normal MRI
  • 11 patients underwent a surgical procedure and half had neurologic signs or symptoms. 10 of them had ligamentous injury, 1 had dural hematoma, and 1 had both

Bottom line: Looks almost compelling, right? One would think that we had better get an MRI on all of these patients! But read more closely, please. Yes, injuries were found. But did they really “require” an intervention? For some injuries, it’s a chip shot. A three column ligamentous injury equals stabilization in any textbook. But management of lesser injuries is less clear. And could some of these injuries have been recognized by a skilled neuroradiologist reading the CT image?

So what to do? There is not enough data for a universal protocol yet. Unfortunately, you will need to develop your own institutional policy based on the experience and opinions of your spine and neurosurgeons. They are the ones who will have to deal with the decision making during and after these studies. Until the definitive study comes along.

Reference: Cervical spine MRI in patients with negative CT: A prospective, multicenter study of the Research Consortium of New England Centers for Trauma (ReCONECT). J Trauma 82(2):263-269, 2017.

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Duplex Ultrasound For DVT: How Does It Work?

Admit it. You’re curious. You order this test for your trauma patients all the time but you’ve never seen it done. It’s simple and noninvasive, but it does require access to all areas to be evaluated. This means that extremities that are casted or splinted, or that have extensive dressings in place may be incompletely evaluated.

The study is called “duplex” because it makes use of two modalities: traditional ultrasound and Doppler ultrasound. Traditional ultrasound is used to view the compressibility of the veins of interest at a number of locations. Doppler measures the speed of blood flow under the probe, and can show areas of sluggish flow.

The following diagram shows the traditional ultrasound technique being used to compress the vein of interest (femoral, popliteal, etc.). Part A shows the probe gently resting over the vessels. Part B shows a fully compressible vein (normal), and Part C shoes partial compression due to the presence of thrombus.

The following diagram shows what the actual ultrasound study looks like. The right side is normal, but the left side shows a venous thrombosis.

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EAST 2017 #6: FAST Exam After Rolling to the Right

The FAST exam is an integral part of trauma evaluation. Even after experience and credentialing of providers, there tends to be some variability in performance. This is especially true when the abnormal findings (or amount of fluid present) is relatively small.

Can we improve this by doing something as simple as using gravity to help? When the patient is supine, fluid tends to pool in the pelvis, where interpretation is a little more complicated.  The surgery program at Guthrie/Packer Hospital created a small pilot study to see if they might improve the sensitivity of FAST by rolling patients to their right briefly, before returning to the supine position and performing the exam.

They enrolled seven participants who were already undergoing peritoneal dialysis (PD), so there was easy access to the peritoneal cavity for administration of known amounts of free fluid. First, each patient was drained of any residual dialysate via their PD catheter. They then underwent a baseline FAST exam. Next, they were placed in the right lateral decubitus position for 30 seconds, then placed supine again and the FAST was repeated. Each patient then had 50cc of dialysate infused, and the process was repeated until a positive FAST was obtained.

Here are the factoids:

  • Of the seven patients recruited, one was excluded because the initial FAST was equivocal due to body habitus and polycystic kidney disease
  • A maximum of 3 aliquots were given (150cc max)
  • Two patients became positive after right side down before any additional fluid was infused
  • None of the four remaining patients had a positive FAST after infusion of any aliquot in the supine position
  • All four became positive after the right side down maneuver,  two after 50cc, one after 100cc, and one after 150cc

Bottom line: The authors conclude that this may be a valuable technique to help detect smaller quantities of fluid than we normally do. I’m not so sure. First, it’s a tiny study in a patient group that is very different from trauma. And it’s impossible to quantify how much dialysate was left after initial drainage of the PD catheter. Finally, we know that FAST can’t “see” small quantities of fluid, but we have constructed our management algorithms around this fact. So we have a good idea of when we should do further imaging or run off to the operating room. Making this test more sensitive may skew these practice guidelines toward doing more (and potentially unneeded) imaging and surgery.

Questions and comments for the authors/presenters:

  • Did you record the volumes and administration times of dialysate given prior to the study? This may correlate with the initial positives and volumes needed to give a positive result.
  • Similarly, did you look at BMI and body habitus to see if there might be a correlation?
  • Are you planning any type of followup study, as you suggested in the abstract?

Click here to go the the EAST 2017 page to see comments on other abstracts.

Related posts:

Reference: Can we be faster? FAST examination after rolling to the right dramatically increases sensitivity. Quick Shot #7, EAST 2017.

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EAST 2017 #5: Subarachnoid Hemorrhage, Neurosurgical Consults, and Repeat Head CT

Neurosurgical involvement in the management of simple traumatic brain injury (TBI) has been slowly dwindling over the past several years. This is the result of the general consensus that very few of these patients progress to need neurosurgical procedures.

A group at Wright State University in Dayton sought to define the progression of one specific finding in TBI, the subarachnoid hemorrhage (SAH). Secondarily, the wanted to determine if a neurosurgery consultation was warranted in these patients.

They performed a five year retrospective review of their registry data, identifying patients with both mild TBI (GCS 13-15) and SAH. They excluded patients with any other brain lesion on CT.

Here are the factoids:

  • 301 patients were enrolled during the 5 year period
  • All had a neurosurgical consultation
  • Time between the initial CT and a followup scan was about 11 hours
  • 91% showed stable or resolving SAH on the followup scan
  • 9% showed a worsening SAH or additional lesions on the repeat scan

Bottom line: The authors conclude that initial neurosurgical consultation is not needed, since only 9% of patients have worrisome findings on repeat CT. They do, however, recommend that the practice of repeat scanning be continued because of this same number.

Our trauma service looked at this issue a year ago, and determined that most of these lesions either do not progress, or never require any intervention if they do, with a few notable exceptions. For that reason, we abandoned both neurosurgical consultation and repeat CT scans for patients with non-aneurysmal SAH, a single parenchymal hemorrhage, or linear skull fractures. We continue to do both for patients with epidural and/or subdural hemorrhage. You can download a copy of this protocol here.

Questions and comments for the authors/presenters:

  • Did you look at platelet count or INR in the study. Were patients excluded based on abnormal values?
  • Did every patient get a repeat scan?
  • Break down the lesions in the 9% of patients who had some sort of progression or new finding. Did you see any common themes (age, chronic alcohol use, etc.)?
  • Did you encounter any patients with “non-central SAH”, that might indicate an aneurysm? How were they dealt with?
  • How has or will your trauma service change its practice based on your findings.

Click here to go the the EAST 2017 page to see comments on other abstracts.

Related posts:

Reference:   Management of subarachnoid hemorrhage (SAH) by the trauma service: are repeat CT scanning & routine neurosurgical consultation necessary? Poster #16, EAST 2017.

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