Category: Radiology

Intermediate-Value CTCA?

Pervasive use of CT coronary angiography has been an unnecessary feature of the evaluation of patient with low-risk chest pain for the better part of a decade now. The argument behind its use – a normal examination confers a durable protective effect – is obviously nonsensical, as this bestows agency upon the test itself. Obviously, in a low-risk population with rare adverse outcomes, there can be no reasonable expectation of value in testing.

The sensible idea, then, is to use CTCA in those patients at intermediate risk. In this trial, the stratification used was GRACE score, and the 1,748 participants in this trial were a mean of 62 years of age, and a GRACE score of 115 (SD ± 35). Patients were eligible by symptoms of an acute coronary syndrome, supported by ECG changes, an elevated troponin, or a history of ischemic heart disease. Patients were then were randomized to receive CTCA in the ED or “standard of care only”. The primary outcome was, naturally, the glorious typical cardiology trial outcome of death or non-fatal myocardial infarction at one year.

Over half of patients included demonstrated troponin levels exceeding the 99th percentile, nearly two-thirds had an abnormal ECG, and a third had known coronary artery disease. Approximately a quarter had previously undergone angiography, with a number also receiving PCI. The vast majority presented with chest pain as their initial complaint.

Most patients randomized to CTCA underwent CTCA; a small number of those randomized to standard care also underwent CTCA within 30 days, as well. About a quarter of patients in this cohort demonstrated normal coronary arteries – a fairly surprising development considering the combination of age, risk factors, elevated troponin, and abnormal electrocardiogram necessary for inclusion. Most patients with normal coronary arteries were predictably managed by medical means alone. The remaining patients demonstrated either non-obstructive coronary disease or obstructive coronary artery disease, with concordant trends towards subsequent invasive coronary angiography.

However, after all of that, even with the added information provided by CTCA, there was no difference in mortality or non-fatal myocardial infarction at one year. Delving into the complexities of subsequent resource utilization, it was noted patients undergoing CTCA were less likely to ultimately undergo invasive coronary angiography, 54.0% vs 60.8%. Similarly, patients with the initial CTCA were less likely to undergo subsequent non-invasive testing, 19.4% vs. 26.2%. Other differences in medical or preventive management did not differ by study arm.

So, a small decrease in invasive testing counterbalanced by the large baseline investment in non-invasive testing – without any clear patient-oriented benefit on health outcomes. CTCA certainly has a role in the evaluation of patients with chest pain and possible CAD, but certainly not as a routine investigation in the ED.

“Early computed tomography coronary angiography in patients with suspected acute coronary syndrome: randomised controlled trial”
https://www.bmj.com/content/374/bmj.n2106

Selective vs. Universal Screening for BCVI

Chasing down cerebrovascular injury is a controversial topic. The incidence of injury to carotid or vertebral arteries following blunt trauma is extremely low, with relative rarity varying by practice setting. Because of its general infrequency, many settings utilize the “Memphis” or “Denver” screening criteria to improve the value of imaging.

These authors, however, describe their implementation of a universal screening protocol for BCVI as routine component of their “whole-body” CT for “all major adult blunt trauma activations”. The data set analyzed is a retrospective local trauma registry from their level 1 trauma center, and 4,687 activations fulfilled their inclusion criteria. The overall incidence of BCVI in their population was 2.7%, with about half of those being grade 3 or higher (pseudoaneurysm or worse).

Based on case review of these 126 patients with BCVIs, only 91 (72%) would have met the current American College of Surgeons guidelines for imaging, with a handful additional more picked up by expanded Denver criteria. The authors’ conclusion – universal screening should be considered – ties in a bit with their bias towards whole-body CT, presuming these additional detected injuries represent potential reduced downstream morbidity and mortality.

It should be clear, however, these data have somewhat limited generalizability to most of Emergency Medicine. The individuals with BCVI in their cohort suffered substantial numbers of skull base fractures, cervical spine fractures, traumatic brain injuries, and had in-hospital mortality of 12.7%. Outside the context of major trauma, universal screening for BCVI will be of limited value. For the vast majority of us, continuing to refer to the most recent EAST recommendations for selective screening remains a reasonable practice. In the narrower context of major trauma referrals, these data could inform more expansive screening protocols, while universal screening for all major trauma is still likely one step too far.

“Blunt Cerebrovascular Injury – The Case for Universal Screening”
https://journals.lww.com/jtrauma/Abstract/9000/BLUNT_CEREBROVASCULAR_INJURY___THE_CASE_FOR.97839.aspx

Potpourri

Just a quick-hit collection of articles I’ve wanted to highlight/catalogue for future reference, but couldn’t find the time for deep dives into each:

Shared Decision Making in Patients With Suspected Uncomplicated Ureterolithiasis: A Decision Aid Development Study.
For this common clinical scenario in the Emergency Department, the authors have developed a patient-facing packet to facilitate shared decision-making. However, more important than the product, is the process these authors have described for its creation. A similar roadmap could be followed to address similar opportunities in your department.

Reduction of Inappropriate Antibiotic Use and Improved Outcomes by Implementation of an Algorithm-Based Clinical Guideline for Nonpurulent Skin and Soft Tissue Infections.
Amazing – using the correct antibiotics reduces treatment failures and, likewise, treatment failures necessitating admission to the hospital. This is an effort-intensive intervention featuring provider education and individual prescribing feedback, but, given the limitations, can be considered a change management success. Whether this can be replicated at your institution will depend on many cultural factors.

Utility of INR For Prediction of Delayed Intracranial Hemorrhage Among Warfarin Users with Head Injury.
Here’s a topic with a ton of practice variation – do you admit patients with closed head injury on anticoagulation for observation? This retrospective review of those patients just on warfarin tries to make the case patients with INR <2 are safe for discharge, whereas those with higher scores are not. Again, however, the yield of observation is somewhere south of 1% in their entire therapeutic cohort, making it truly challenging to find the inflection point of value. Another opportunity for shared decision-making?

Performance of Novel High-Sensitivity Cardiac Troponin I Assays for 0/1-Hour and 0/2- to 3-Hour Evaluations for Acute Myocardial Infarction: Results From the HIGH-US Study.
A detailed look at high-sensitivity Troponin I rule-in/rule-out algorithms suggests a 0/1-hour strategy is similar to a 0/3-hour strategy. Overall, while the disposition of patients is likely to be more rapid from the 0/1 hour strategy, a greater proportion of patients ultimately fall into the “intermediate” zone requiring further observation and diagnostics. Certainly, combinations of hsTnI and other risk-stratification instruments ought to mean the majority of patients with straightforward chest pain presentations may be discharged from the Emergency Department.

Randomized Clinical Trial of IV Acetaminophen as an Adjunct to IV Hydromorphone for Acute Severe Pain in Emergency Department Patients.
In this trial, patients receiving hydromorphone were randomized to receive adjunctive treatment with IV acetaminophen or placebo. With 159 patients, they found advantages to the multi-modal approach favoring the addition of acetaminophen – but the confidence interval for their primary outcome crossed unity by 0.01. The authors conclude this is a negative trial, but it rather seems to me there’s certainly no harm in adding acetaminophen (it need not be IV) – adding it likely has a favorable effect, even if the effect size may not be large.

Effect of No Prehydration vs Sodium Bicarbonate Prehydration Prior to Contrast-Enhanced Computed Tomography in the Prevention of Postcontrast Acute Kidney Injury in Adults With Chronic Kidney Disease: The Kompas Randomized Clinical Trial.
In news surprising no one, another trial fails to show benefit of prehydration in staving off post-contrast exposure acute kidney injury. As seen on Twitter, rather than “contrast-induced nephropathy”, the clinical paradigm is effectively “contrast-adjacent nephropathy.” The impairment in renal function is associated with the underlying medical illness and not the exposure to IV contrast. Thus, no intervention – such as prehydration – can prevent such.

Coronary CT Angiography in Patients With Non-ST-Segment Elevation Acute Coronary Syndrome.
This interesting observational study evaluated patients with a diagnosis of non-ST elevation acute coronary syndrome using coronary CT angiography prior to invasive coronary angiography. The good news: CT angiography was probably useful at excluding obstructive coronary disease. The bad news: nearly 70% of patients had a coronary stenosis identified on invasive angiography, so patient selection prior to CT angiography will be important to improve the value of using it as a screen to prevent invasive angiography.

Industry Payment to Vascular Neurologists: A 6-Year Analysis of the Open Payments Program From 2013 Through 2018.
As we watch our healthcare delivery system struggle and groan under the various strains and burdens, one of the culprits has always been the influence of pharmaceutical/device manufacturers targeting investments to improve uptake of their products. In this observational analysis of the OpenPayments database, these authors identified the recipients of financial support from the manufacturers of endovascular devices. About 16% of vascular neurologists received funding from industry, but over 75% could be identified as “influencers” – chiefs of staff, department chairs, or similar. Pharma et al should always be remembered they are serving the interests of owners and shareholders, and not patients and our healthcare system.

IV Contrast, Unleashed

“The putative risk of administering modern intravenous iodinated contrast media in patients with reduced kidney function has been overstated.”

What a glorious lead sentence to the summary of this most recent guideline, a product of the American College of Radiology and the National Kidney Foundation. Historically, there has been great concern – including delay or exclusion of imaging – regarding the potential for acute kidney injury from intravenous contrast media in advanced imaging. However, a variety of recent different pieces of evidence have led to changes in perspective. This lovely guideline summarizes the data and issues a panoply of clarifications and recommendations regarding its use.

The most important distinction this guideline makes is between contrast-associated AKI and contrast-induced AKI. CA-AKI, as the authors note, is quite common – but is a rather a product of the underlying medical illness rather than the administration of IV contrast. CI-AKI, the attributable injury associated with IV contrast, is much harder to reliably observe. As noted in this article, summarizing mostly observational data sets, tweezing out the actual risk of harm from IV contrast media is challenging.

This guideline bundles together a whole list of concise questions and answers with regard to which patients may be at risk, the reliability of those estimates of risk, and what – if any – prophylaxis could be considered. Effectively – and the authors use many more words to clarify individual scenarios – the uncertainty regarding the safety of IV contrast begins to creep in around an eGFR of 30mL/Min/1.73m2. It should be noted this is related to a paucity of data, rather than a known observable risk. The authors recommendation, however, is not to exclude these patients from imaging, but rather to prompt a conversation between the referring professional and the radiologist to discuss the risks and benefits of IV contrast. Certainly life-threatening illnesses may require imaging, thus the careful weighing of risks versus benefits, and in these areas of uncertainly, additional cognitive consideration is reasonable.

With regard to prophylaxis against CI-AKI, the authors also make eminently reasonable statements saline volume expansion could be considered if clinically tolerated. The authors note this recommendation is based rather on observations of the utility of volume expansion for treating CA-AKI rather than CI-AKI, specifically, but likely represents a reasonable clinical practice.

In all, these guidelines quite nicely represent the uncertainly regarding harms from IV contrast administration, and, absent known harms from contrast, the potential harms from exclusion of IV contrast. As with most clinical problems, additional prospective research is critical to better inform practice.

“Use of Intravenous Iodinated Contrast Media in Patients with Kidney Disease: Consensus Statements from the American College of Radiology and the National Kidney Foundation”
https://pubs.rsna.org/doi/10.1148/radiol.2019192094

The Clinical Impact of SAH Decision Rules

The Ottawa Subarachnoid Hemorrhage Rule has been around a long time now, dating back to 2013. The “six hour CT” rule has been around even longer, dating back even to 2011. They’ve become entwined in at least the discussion around the evaluation of SAH, if not clinical practice.

… but are they actually useful?

This is the “before and after” study from Perry and Stiell (not to be confused with Penn and Teller), in which the practice of Canadian physicians was examined around the time these rules were under development and in publication. These authors gathered data on patients presenting with atraumatic headache spanning the time period between 2011 and 2016, looking at resource utilization and missed SAH before and after adoption of both the Ottawa SAH Rule and the 6-hour CT Rule. Specifically, practicing clinicians were instructed not to use decision rules for the basis of patient care until June 2013, at which point clinicians were actively encouraged to do so.

The basic findings:

  • The Ottawa SAH Rule doesn’t change much.
  • The 6-hour CT Rule probably reduces downstream lumbar puncture/CTA.

Again, with concern for generalizability, a full 5.1% of their qualifying atraumatic headaches were diagnosed with SAH across the study period. The rate of investigation of these patients remained high, about 88%, regardless of study period – and regardless whether the Ottawa Rule criteria were met. However, for patients presenting within 6 hours of headache onset, the rate of subsequent LP dropped from 31.3% to 15.1%. The Ottawa SAH Rule showed its expected specificity of about 12%, and, therefore, was 100% sensitive. The 6-hour CT Rule “missed” 5 of 111 patients, however, for various reasons – one radiology misread, a false-positive owing to profound anemia, a non-aneurysmal SAH from dural vein fistula, and two cases of false-positive LPs meeting their study criteria for false-negative CT.

A long story made short, 1) keep using the 6-hour CT rule with the caveat of known potential confounders to visible blood (anemia); 2) the Ottawa Rule is only clinical useful as a one-way decision instrument owing to its poor positive likelihood ratio.

“Prospective Implementation of the Ottawa Subarachnoid Hemorrhage Rule and 6-Hour Computed Tomography Rule”

https://www.ncbi.nlm.nih.gov/pubmed/31805846

The CT and Syncope

The Choosing Wisely Campaign lists non-contrast CT of the head as one of their low-value procedures for low-risk patients presenting with syncope. However, despite these recommendations, these authors voice concerns up to two-thirds of patients still undergo advanced imaging.

In this systematic review looking at both practice patterns and yield, the authors identify 17 studies of both hospitalized and Emergency Department patients addressing this topic. Pooling together 1,669 ED patients, 55% underwent CT with a yield of 3.8%. Pooling 1,289 hospitalized patients, CTs were performed 45% of the time with a yield of 1.2%. Considering the general morbidity and mortality associated with intracranial conditions, these are not fantastic yield numbers, but are not entirely unreasonable.

There is a bit of trouble with these numbers, however: even though their systematic review went up to 2017, most of the included studies were published before 2011. Even their citation of “two-thirds receiving head CTs” was published in 2009, well before the 2014 Choosing Wisely statement. Then, the bulk of the included studies were retrospective, blurring the reliability of their inclusion and outcomes measurement.

I think these data probably effectively illustrate the rarity of serious outcomes in syncope, but provide little insight into the current scope of the problem with respect to overuse. An intracranial process or intracranial injury associated with syncope ought to be considered in each case, but better data describing features predictive of underlying intracranial injury is needed to better separate high-risk from low-risk.

“The Yield of Computed Tomography of the Head Among Patients Presenting With Syncope: A Systematic Review”
https://www.ncbi.nlm.nih.gov/pubmed/31006937

Who Recanalizes with Just tPA?

The original argument: tPA helps all strokes, we must give it to everyone as quickly as possible!
The updated argument: tPA doesn’t not help all strokes, so it should still be given!

Specifically, as applies to the cohort of patients with large vessel occlusions being considered for mechanical thrombectomy. This small, pooled registry sample looked at cases from four centers, evaluating the rate and predictive characteristics for recanalization prior to cerebral angiography. The stated purpose of their study was to develop a predictive score, with the reasonable goal of reducing unnecessary tPA exposures prior to thrombectomy.

The numbers, in their score derivation and validation cohorts:

  • ICA: 6.4%/1.0%
  • M1 proximal: 16.1%/13.7%
  • M1 distal: 30.3%/30.7%
  • M2: 33.7%/34.0%

But, an even more powerful a predictor was thrombus length, as measured by T2 MRI susceptibility vessel sign. Recanalization was seen at over 80% for clots <5mm, 30% for 6-10mm, and below 10% for clots longer than 10mm, with particular futility for >20mm.

Interesting data – and a nice look at how not all sites of occlusion and clots are created equal. Whether, and how, we ought to treat them differently remains uncertain until the results of a prospective trial.

“Post-Thrombolysis Recanalization in Stroke Referrals for Thrombectomy”
https://www.ahajournals.org/doi/pdf/10.1161/STROKEAHA.118.022335

Again With The Value of CT-Diagnosed Rib Fractures

The elderly are more likely to fall. The elderly who fall are more likely to suffer rib fractures. The elderly who fall and suffer rib fractures are more likely to contract pneumonia and die. The chest x-ray is insensitive for rib fractures. So, we should always perform a CT in the elderly who fall and of whom we have suspicion for rib fractures?

This is a single-center retrospective study of 330 elderly patients, mean age 84, who presented after a fall. Each patient included in the study received a chest XR, followed by a CT of their chest. Overall, 96 patients had a rib fracture – 40 of which were seen on XR, the remainder only on CT. And, there are a number of interesting tidbits they describe in their population:

  • Neither hospital length-of-stay, ICU length-of-stay, or hospital mortality (10.3% vs. 7.3%) were (statistically) increased in those with occult rib fractures compared to those without any rib fractures.
  • These findings held true for the 63 patients with ≥2 occult rib fractures (both XR+ and XR-).
  • In patients with rib fractures seen on XR, the median number of additional rib fractures seen on CT was 2 (range 0-11).

Rates of in-hospital complications were similar between those hospitalized with rib fractures visualized on XR and those visualized only on CT. Then, in their case review, most adverse events occurring in those with occult rib fractures occurred due to associated injuries, events, or iatrogenic causes – not primarily due to the thoracic trauma itself.

This is only a small case series, and it is biased towards higher acuity – considering clinician judgement obtained CT imaging in all cases, and admission rates were nearly 90%. However, it does generally further demonstrate the low value in obtaining CT imaging to ensure no occult rib fractures are missed. An XR has low sensitivity, but these data do not support a premise of increased harm due to missed occult fractures.

“Chest CT imaging utility for radiographically occult rib fractures in elderly fall-injured patients”

https://journals.lww.com/jtrauma/Abstract/publishahead/Chest_CT_imaging_utility_for_radiographically.98414.aspx

Did You Miss … CATCH2?

We’ve talked about the PECARN vs. CATCH vs. CHALICE cage-match before. PECARN has been the subject of multiple sub-investigations, but CHALICE has been neglected and gone to seed. CATCH, on the other hand, has a sequel.

What’s new in CATCH2? Vomiting!

Adding to the original 4 + 3 item list, these authors conducted a new multi-center study comprised of 4,060 children with minor head injury. The stated purpose was to prospectively evaluate CATCH, with a secondary plan to improve performance if found to be deficient – and, although it is not explicitly stated, it appears these authors anticipated the missing link to be inclusion of vomiting.

Only 23 children in their cohort required neurosurgical intervention, while 197 had any brain injury on CT. The original CATCH had sensitivity of 97.5% and specificity of 59.6% for any brain injury, while adding “≥4 episodes of vomiting” increased sensitivity to 99.5% and decreased specificity to 47.8%. Sensitivity of CATCH2 was 100% for any cases requiring neurosurgical intervention, although confidence intervals are obviously wide, given the paucity of events.

So, another entrant arrives to the pediatric head injury decision-instrument sweepstakes. Interestingly enough, these instruments were created because of concerns of CT overuse – up to 53% in 2005! – as cited by these authors. With CATCH2, the CT ordering rate would be 55%. This is both greater than the 34% rate witnessed in this study, and vastly greater than the 8% seen in Australian and New Zealand, although with different entry criteria. It would seem to me these instruments are rather making the problem worse, rather than better ….

“Validation and refinement of a clinical decision rule for the use of computed tomography in children with minor head injury in the emergency department”
http://www.cmaj.ca/content/190/27/E816

I Choose You! Observation, I Hope.

We’re back with another patient-oriented clinical decision aid from the folks who brought you Chest Pain Choice – Pediatric Head CT Choice! In this episode, our noble heroes are out to educate parents regarding the risk of intracranial injury in children who are at “intermediate risk” for clinically-important traumatic brain injury by PECARN criteria.

In this multicenter, cluster-randomized, controlled-trial, these authors tested an information graphic and educational tool against usual care, with a primary outcome of parental knowledge. Additional measures of engagement in the decision-making processes, decisional conflict, and parental trust were measured as secondary outcomes related to the cognitive aspects, along with patient-oriented outcomes such as ciTBI and imaging utilization. They included 172 clinicians at 7 sites, and enrolled 971 patients, including 516 patients who consented for recording of their discussion regarding imaging. Follow-up by telephone was obtained in 890 (92%) of patients, with the remainder of outcomes assessment limited to electronic health record and vital records follow-up.

The results are mostly good news regarding the decision aid. Parents in the intervention arm could answer 6 of 10 questions about their choice correctly, compared with 5 of 10 receiving usual care. Secondary cognitive outcomes also favored the decision instrument, and physicians surveyed were generally in favor of the decision aid, as well. Imaging at the index visit was similar between the two groups, but downstream healthcare resource use and subsequent imaging was lower in the decision aid cohort.

There are findings here to critique, of course. There was only one ciTBI in the entire cohort, and they were imaged at the index visit. The expectation – and the tool – were constructed based on a 0.9% ciTBI rate, when the actual observed incidence was 0.1%. It is reasonable to consider the practical implementation of PECARN over-classifies patients into the “intermediate risk” cohort, placing additional children at risk for unneeded imaging – which, in turn, renders their “1 in 100” information graphic misleading. Then, clinicians spent an extra 2 minutes – 38% longer – with parents when using the decision aid. How much of the improved knowledge and trust stems from the decision aid, and how much from simply spending more time in the discussion? Finally, there are uncertain manifestations of the Hawthorne effect, particularly considering over half the encounters were recorded.

Overall, however, I have few quibbles with this decision aid. At the least, it is unlikely to exert a negative effect on parental knowledge or paradoxically increase unnecessary scanning.

“Effect of the Head Computed Tomography Choice Decision Aid in Parents of Children With Minor Head Trauma”
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2703135