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The effect of imprecise repositioning on lesion volume measurements in patients with multiple sclerosis
M Filippi1, N Marcianò, R Capra
1Department of Neurology, Scientific Institute Ospedale San Raffaele, University of Milan, Italy.
Abstract:
In this study, we evaluated the effect of imprecision in patient repositioning encountered in real life on multiple sclerosis (MS) lesion volumes measured from MRIs. We also evaluated two putative methods for reducing the variability in these lesion volume measurements: first, a reduction of slice thickness (from the conventional 5 mm to 3 mm) and second, the application of a new repositioning technique based on the use of head immobilization shells. We evaluated the errors in lesion volume by scanning 10 patients a total of four times using the two slice thicknesses and two repositioning methods (conventional and using a head immobilization shell). The mean absolute percentage difference between two corresponding scans was 6.8% (range, 1.24 to 11%) using conventional slice thickness and repositioning, 4.1% (range, 0.7 to 5.56%) using conventional slice thickness and head immobilization shells, 2.6% (range, 0.8 to 6.66%) using the conventional repositioning technique and 3-mm slice thickness, and 1.4% (range, 0.2 to 6.14%) using slice thickness of 3 mm and head immobilization shells. These mean absolute differences were significantly different (p = 0.0008). Our results indicate that the effect of repositioning errors of the order of those that can be encountered in the daily life situation of clinical trials affects significantly lesion load measurements in MS and that the combined use of thinner slices and more accurate repositioning techniques can markedly improve the reproducibility of such measurements.
Insights
Patient repositioning errors significantly impact multiple sclerosis (MS) lesion volume measurements. Combining thinner MRI slices (3 mm) and head immobilization shells markedly improves measurement reproducibility in clinical trials.
Area of Science:
- Radiology
- Neurology
- Medical Imaging
Background:
- Accurate measurement of multiple sclerosis (MS) lesion volumes from MRI is crucial for tracking disease progression and treatment efficacy.
- Patient repositioning errors in clinical settings can introduce variability into these measurements.
- Conventional MRI protocols may not adequately address repositioning inaccuracies.
Purpose of the Study:
- To evaluate the impact of real-life patient repositioning imprecision on MS lesion volume measurements.
- To assess the effectiveness of reducing MRI slice thickness and employing a head immobilization technique in reducing measurement variability.
- To determine optimal methods for enhancing the reproducibility of MS lesion load quantification.
Main Methods:
- Ten patients with MS underwent four MRI scans each.
- Scans were performed using conventional (5 mm) and reduced (3 mm) slice thicknesses.
- Two repositioning techniques were compared: conventional and a novel head immobilization shell method.
- Lesion volumes were calculated, and mean absolute percentage differences between scans were analyzed.
Main Results:
- Conventional methods resulted in a mean absolute percentage difference of 6.8%.
- Using head immobilization shells with conventional slice thickness reduced the difference to 4.1%.
- Employing 3-mm slices with conventional repositioning decreased the difference to 2.6%.
- The combination of 3-mm slices and head immobilization shells yielded the lowest difference at 1.4% (p = 0.0008).
Conclusions:
- Patient repositioning errors significantly affect MS lesion load measurements in clinical trials.
- Reducing MRI slice thickness to 3 mm improves measurement reproducibility.
- The combined use of thinner slices and head immobilization shells offers a marked improvement in the reproducibility of MS lesion volume measurements.