Low-Cost Smartphone-Based Photogrammetry for the Analysis of Cranial Deformation in Infants
Innes Barbero-García1, José Luis Lerma1, Ángel Marqués-Mateu1
1Photogrammetry & Laser Scanning Research Group (GIFLE), Department of Cartographic Engineering, Geodesy and Photogrammetry, Universitat Politècnica de València, Camino de Vera, Valencia, Spain.
Insights
Smartphone photogrammetry offers a low-cost method for evaluating infant cranial deformation, providing detailed 3D head models. This technique shows high accuracy when head markers are used, improving upon traditional manual measurements.
Area of Science:
- Medical Imaging
- Pediatrics
- Biomedical Engineering
Background:
- Infant cranial deformation, including plagiocephaly and brachycephaly, is common but lacks standardized evaluation methods.
- Current manual caliper measurements are debated for accuracy, while 3D photography and scanners are costly or invasive.
- There is a need for a novel, low-cost, and minimally invasive method for assessing cranial deformation.
Purpose of the Study:
- To develop and validate a novel, low-cost, and minimally invasive methodology for evaluating infant cranial deformation using 3D imagery.
- To compare the accuracy of smartphone-based photogrammetry with traditional manual measurements.
Main Methods:
- Utilized smartphone slow-motion video to capture head data from 5 infant patients.
- Processed video sequences to generate accurate 3D head models.
- Compared 3D model measurements with manual caliper measurements.
Main Results:
- High correspondence between manual and photogrammetric measurements (2 mm ± 0.9 mm difference) was achieved when head markers were present.
- Without head markers, measurement discrepancies increased significantly, up to 20 mm.
- Smartphone photogrammetry provided substantially more information than linear measurements.
Conclusions:
- Smartphone-based photogrammetry is a cost-effective and valuable tool for assessing cranial deformation.
- The technique offers comparable accuracy to manual methods when head markers are utilized.
- A novel evaluation approach involves comparing the 3D head model to an ideal 3-axis ellipsoid head shape.
Background:
Cranial deformation, including deformational plagiocephaly, brachycephaly, and craniosynostosis, is a condition that affects a large number of infants. Despite its prevalence, there are no standards for the systematic evaluation of the cranial deformation. Usually, the deformation is measured manually by the use of calipers. Experts, however, do not agree on the suitability of these measurements to correctly represent the deformation. Other methodologies for evaluation include 3-dimensional (3D) photography and radiologic scanners. These techniques require either patient's sedation and ionizing radiation or high investment. The aim of this study is to develop a novel, low-cost, and minimally invasive methodology to correctly evaluate the cranial deformation using 3D imagery.
Methods:
A smart phone was used to record a slow motion video sequence on 5 different patients. Then, the videos were processed to create accurate 3D models of the patients' head, and the results were compared with the measurements obtained by the manual caliper.
Results:
The correspondence between the manual and the photogrammetric 3D model measurements was high as far as head marks are available, with differences of 2 mm ± 0.9 mm; without marks, measurement results differed up to 20 mm.
Conclusions:
Smartphone-based photogrammetry is a low-cost, highly useful methodology to evaluate cranial deformation. This technique provides a much larger quantity of information than linear measurements with a similar accuracy as far as head marks exist. In addition, a new approach for the evaluation is pointed out: the comparison between the head 3D model and an ideal head, represented by a 3-axis ellipsoid.
