Systematic Transcranial Doppler Examination in Adults with Sickle Cell Disease : A Cross-Sectional Single Center Study
Bibliographic record
Abstract
Background Individuals with sickle cell disease (SCD) are at a high risk of stroke throughout their lifespan. Regular transcranial doppler (TCD) screening is widely adopted for children with SCD to identify those in need of treatment intensification. However, TCD screening is not routinely performed beyond ages 16-18. Data on TCD feasibility and standard velocities in adults with SCD are limited. Since 2021, all adults with SCD followed at the Centre Hospitalier de l'Université de Montréal (CHUM) Comprehensive SCD Centre are referred for TCD examination as part of routine neurovascular surveillance, regardless of their genotype, age, comorbidities, or neurologic status. ObjectivesThe primary aim of this study is to determine the feasibility of TCD in unselected adults with SCD. The secondary aim is to report the distribution of Doppler velocities in this population. We also aimed to explore associations between these measures and biological and clinical patient characteristics. Methods In this retrospective study, clinical data of all patients seen at the SCD Center between September 2021 and June 2024 were reviewed and extracted.Patients with routine TCD examination were included in the study sample. Mean flow velocity (MFV) measurements were attempted in all patients for the anterior cerebral artery (ACA), the middle cerebral artery (MCA), the posterior cerebral artery (PCA), and the basilar artery (BasA). Feasibility was assessed using the following definitions: “standard TCD” with successful insonation of both MCA, and “complete TCD” for successful insonation of bilateral MCA, ACA, PCA and BasA. Chi-squared test was used to compare feasibility across predetermined groups (age, sex, genotype and body mass index (BMI)). Distribution of MFV was calculated as mean ± standard deviation (SD). A priori determined covariates tested for univariate linear association with MFV were age, sex, genotype, BMI, hemoglobin (Hb) and hematocrit (Hct). The project was approved by the local ethics committee.Results A total of 249 SCD patients with a documented TCD examination were analyzed (mean age 35 [range 18 to 79 years], 141 (57%) were women). Overall, 115 (46%) patients had a SS/Sβ0 and 134 (54%) a SC/Sβ+ genotype. A prior diagnosis of cognitive disorder was present in 4 (2%), and of stroke in 19 (8%) cases. A majority of 156 patients (63%) were on hydroxyurea (HU) treatment alone, while 65 (26%) were on transfusions, and 18 (7%) on both treatments. A “standard” TCD examination was feasible in 229 (92%) patients, while a “complete” TCD was successfully documented in 190 (76%). There was no statistically significant effect of sex, age, genotype and BMI on TCD feasibility. Documented MFV (±SD) for cerebral arteries were as follows: MCAleft 67 (±19) cm/s; right 67 (±19) cm/s;ACAleft 53 (±16) cm/s; right 52 (±15) cm/s;PCAleft 37 (±12) cm/s; right 38 (±12) cm/s;BasA43 (±14) cm/s Linear regression showed increasing age was inversely associated with MFV in all arteries (p≤0.002). For each additional 10 years, a decrease of MFV (±SD) in the respective brain arteries was as follows: MCAleft -4.8 (±1.0); right -3.6 (±1.0) cm/s;ACAleft -3.1 (±1.0); right -2.9 (±0.9) cm/s;PCAleft -2.6 (±0.7); right -2.2 (±0.7) cm/s;BasA-3.3 (±0.7) cm/s. Female sex was associated with higher MFV in the left ACM and both PCA (p<0.05). MFV were negatively correlated with Hb and Hct for all arteries (p<0.005 for all). MFV were higher in the HbSS/Sβ0, compared to the HbSC/Sβ+ group (p<0.05). Conclusion : Our study showed that TCD can be implemented in routine follow-up of adult patients with SCD with a high (92%) success rate for standard MCA evaluation. Overall, measured intracranial velocities were in line with previously established patterns showing an inverse association with age throughout adulthood. Longitudinal TCD follow-up may help to further determine the role of intracranial flow parameters in the neurovascular risk assessment of adults with SCD.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".