Color Doppler Ultrasound (CDUS) is a noninvasive imaging technique that combines traditional B-mode ultrasound with Doppler effect analysis to visualize and measure blood flow in real time.
The terms Color Doppler Ultrasound (CDUS) and Duplex Ultrasound are related but not interchangeable.
Combines B-mode imaging with color flow mapping based on Doppler shifts. It provides a qualitative visualization of blood flow direction and relative velocity.
Combines B-mode imaging with spectral (pulsed-wave) Doppler, producing a waveform for quantitative velocity measurements.
The most complete form. Combines:
→ Offers both visual and quantitative data.
| Term | Includes Color Flow | Includes Velocity Curve | Includes B-mode Image | Quantitative? |
|---|---|---|---|---|
| Color Doppler (CDUS) | ✅ Yes | ❌ No | ✅ Yes | ❌ No |
| Duplex Ultrasound | ❌ No | ✅ Yes | ✅ Yes | ✅ Yes |
| Color Flow Duplex Ultrasound | ✅ Yes | ✅ Yes | ✅ Yes | ✅ Yes |
If a method includes color mapping + waveform + anatomy, the correct term is:
Color Flow Duplex Ultrasound
`(PSV - EDV) / PSV`
Wang et al. in a prospective observational cohort study with control groups, attempt to introduce Color Doppler ultrasound (CDUS) of the middle meningeal artery (MMA) as a tool for predicting chronic subdural hematoma recurrence 1) Unfortunately, their study suffers from serious methodological weaknesses, conceptual overreach, and overinterpretation of surrogate markers.
❌ 1. Anatomical Fantasy: The “Half-Open Mouth” Miracle
The claim that CDUS can reliably visualize the MMA through the infratemporal fossa using a “half-mouth” technique is anatomically fragile at best. The MMA lies deep, tortuous, and surrounded by bone—barely accessible by Doppler. The 84% visualization rate reported is suspiciously high and lacks independent validation. There's no mention of inter-rater reliability, probe angle reproducibility, or validation against angiographic imaging (the actual gold standard).
❌ 2. Statistical Acrobatics: Logistic Regression on Sand
The study applies multivariate logistic regression to a sample of 87 post-op patients, yet:
There's no mention of power analysis to ensure the sample size supports multiple predictors.
The analysis does not account for confounding variables like hematoma volume, use of corticosteroids, or brain atrophy.
Bilateral hematoma, a known recurrence factor, is conveniently thrown in without adjusting for interaction terms.
This is p-hacking disguised as multivariate modeling.
❌ 3. Hemodynamic Overreach: PSV and RI as Destiny?
Using PSV >30.85 cm/s and RI <0.78 as thresholds for predicting recurrence stretches biological plausibility:
No mechanistic explanation is provided for how extracranial MMA flow directly causes hematoma recurrence.
The assumption that flow changes = pathological recurrence is a textbook example of surrogate endpoint fallacy.
Receiver Operating Characteristic (ROC) analysis is performed without external validation, making the proposed cutoffs clinically meaningless.
❌ 4. Interpretative Overconfidence: Weak Data, Strong Claims
The authors leap from shaky Doppler signals to a sweeping clinical conclusion: that CDUS “holds significant value” for recurrence prediction. Yet:
No comparative cohort with angiography or embolization is included.
Follow-up duration is not clearly stated.
There’s no mention of blinding, introducing a clear observer bias.
❌ 5. Clinical Usefulness: Zero Impact
Even if true, would a PSV of 31 cm/s change practice? Not really. The decision to embolize or reoperate is guided by clinical deterioration and imaging, not Doppler velocities from a speculative technique.
🧨 Conclusion:
This study is a textbook case of “technological enthusiasm meets poor methodology”. It proposes a solution for a non-problem (CSDH recurrence prediction has better tools), based on a weak signal (MMA Doppler), in a poorly designed study, with overconfident conclusions.
Until independently validated and proven superior to existing clinical predictors, this technique is best kept in the realm of academic curiosities—not neurosurgical guidelines.