Background
The anatomy of carotid stenosis may influence the outcome of endovascular treatment or carotid endarterectomy. Whether anatomy favors one treatment over the other in terms of safety or ...efficacy has not been investigated in randomized trials.
Methods
In 414 patients with mostly symptomatic carotid stenosis randomized to endovascular treatment (angioplasty or stenting; n = 213) or carotid endarterectomy (n = 211) in the Carotid and Vertebral Artery Transluminal Angioplasty Study (CAVATAS), the degree and length of stenosis and plaque surface irregularity were assessed on baseline intraarterial angiography. Outcome measures were stroke or death occurring between randomization and 30 days after treatment, and ipsilateral stroke and restenosis ⩾50% during follow-up.
Results
Carotid stenosis longer than 0·65 times the common carotid artery diameter was associated with increased risk of peri-procedural stroke or death after both endovascular treatment odds ratio 2·79 (1·17–6·65), P = 0·02 and carotid endarterectomy 2·43 (1·03–5·73), P = 0·04, and with increased long-term risk of restenosis in endovascular treatment hazard ratio 1·68 (1·12–2·53), P = 0·01. The excess in restenosis after endovascular treatment compared with carotid endarterectomy was significantly greater in patients with long stenosis than with short stenosis at baseline (interaction P = 0·003). Results remained significant after multivariate adjustment. No associations were found for degree of stenosis and plaque surface.
Conclusions
Increasing stenosis length is an independent risk factor for peri-procedural stroke or death in endovascular treatment and carotid endarterectomy, without favoring one treatment over the other. However, the excess restenosis rate after endovascular treatment compared with carotid endarterectomy increases with longer stenosis at baseline. Stenosis length merits further investigation in carotid revascularisation trials.
Purpose
Digitally reconstructed radiographs (DRRs) are routinely used as an a priori reference for setup correction in radiotherapy. The spatial resolution of DRRs may be improved to reduce setup ...error in fractionated radiotherapy treatment protocols. The influence of finer CT slice thickness reconstruction (STR) and resultant increased resolution DRRs on physician setup accuracy was prospectively evaluated.
Methods
Four head and neck patient CT-simulation images were acquired and used to create DRR cohorts by varying STRs at 0.5, 1, 2, 2.5, and 3 mm. DRRs were displaced relative to a fixed isocenter using 0–5 mm random shifts in the three cardinal axes. Physician observers reviewed DRRs of varying STRs and displacements and then aligned reference and test DRRs replicating daily KV imaging workflow. A total of 1,064 images were reviewed by four blinded physicians. Observer errors were analyzed using nonparametric statistics (Friedman’s test) to determine whether STR cohorts had detectably different displacement profiles. Post hoc bootstrap resampling was applied to evaluate potential generalizability.
Results
The observer-based trial revealed a statistically significant difference between cohort means for observer displacement vector error (
p
=
0.02
) and for
Z
-axis
(
p
<
0.01
)
. Bootstrap analysis suggests a 15 % gain in isocenter translational setup error with reduction of STR from 3 mm to
≤
2 mm, though interobserver variance was a larger feature than STR-associated measurement variance.
Conclusions
Higher resolution DRRs generated using finer CT scan STR resulted in improved observer performance at shift detection and could decrease operator-dependent geometric error. Ideally, CT STRs
≤
2 mm should be utilized for DRR generation in the head and neck.
Shiga-toxigenic Escherichia coli O157:H7 (STEC O157:H7) is associated with potentially fatal human disease, and a persistent reservoir of the organism is present in some farm animal species, ...especially cattle and sheep. The mechanisms of persistent colonisation of the ruminant intestine by STEC O157:H7 are poorly understood but may be associated with intimate adherence to eukaryotic cells. Intimate adherence, as evidenced by induction of attaching-effacing (AE) lesions by STEC O157, has been observed in 6-day-old conventional lambs after deliberate oral infection but not in older animals. Thus, the present study used a ligated intestinal loop technique to investigate whether STEC O157:H7 and other attaching-effacing E. coli may adhere intimately to the sheep large intestinal mucosa. To do this, four STEC O157:H7 strains, one STEC O26:K60:H11 and one Shiga toxin-negative E. coli O157:H7 strain, suspended in either phosphate-buffered saline or Dulbecco's modified Eagle's medium, were inoculated into ligated spiral colon loops of each of two lambs. The loops were removed 6 h after inoculation, fixed and examined by light and electron microscopy. AE lesions on the intestinal mucosa were produced by all the inoculated strains. However, the lesions were sparse and small, typically comprising bacterial cells intimately adhered to a single enterocyte, or a few adjacent enterocytes. There was little correlation between the extent of intimate adherence in this model and the bacterial cell density, pre-inoculation growth conditions of the bacteria or the strain tested.
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