Elastic phantoms generated by microfluidics technology: Validation of an imaged‐based approach for accurate measurement of the growth rate of lung nodules

Abstract

This paper focuses on validating our approach for monitoring the development of lung nodules detected in successive chest low-dose computed tomography (LDCT) scans of a patient. Our methodology for monitoring detected lung nodules includes 3D LDCT data registration, which is a non-rigid technique and involves two steps: (i) global target-to-prototype alignment of one scan to another using the experience gained from a prior appearance model, followed by (ii) local alignment to correct for intricate relative deformations. We propose a new approach for validating the accuracy of our algorithm for elastic lung phantoms constructed with state-of-the-art microfluidics technology and in vivo data. Fabricated from a flexible transparent polymer, i.e. polydimethylsiloxane (PDMS), the phantoms mimic the contractions and expansions of the lung and nodules as seen during normal breathing. The in vivo data in our study had been collected from a small control group of four subjects and a larger test group of 27 subjects with known ground truth (biopsy diagnosis. The growth rate and diagnostic results for both phantoms and in vivo data confirm the high accuracy of our algorithm.

Computer-Aided Diagnosis Systems for Lung Cancer: Challenges and Methodologies

“…Another trend describes the lung nodule's shape by representing its 3D surface with a linear combination of spherical harmonics (SH) [247, 355–358]. The recent works suggested employing different types of appearance and shape features to achieve better detection and diagnosis of lung nodules.Investigations of using the microfluidics technology to mimic the contractions and expansions of the lung and nodules during normal breathing have recently been explored to provide more realistic phantoms in order to validate the volumetric growth rate measurements [305–307]. …”

“…Investigations of using the microfluidics technology to mimic the contractions and expansions of the lung and nodules during normal breathing have recently been explored to provide more realistic phantoms in order to validate the volumetric growth rate measurements [305–307]. …”

“…Many studies have utilized various phantom scans for tuning parameters and bench-marking their best possible performance in vivo [140, 141, 146, 153, 154, 164, 176, 204, 302–304]. Recently, El-Baz et al [305–307] validated the growth rate volumetric measurements on elastic lung synthetic phantoms. They developed more realistic phantoms using a state-of-the-art microfluidics technology to mimic the contractions and expansions of the lung and nodules seen during normal breathing.…”

“…Also, some researchers used a number of commercial packages that have been released by the CT vendors for measuring the volume of pulmonary nodules, and a number of studies have evaluated the accuracy and limitations of these software packages. Since the actual volumes of real pulmonary nodules are unknown, such evaluations usually involve either radiologists/experts as the “gold standard” [200, 202, 203, 205, 207] or synthetic phantoms for which the volumes of the nodules are known [146, 204, 305–307, 338]. A general limitation of the majority of the volumetric measurement algorithms is that they are only capable of segmenting solid nodules.…”

Performance evaluation of an automatic MGRF-based lung segmentation approach

“…However, this "gold standard" ground truth may not be accurate due to hand shaking and observer's variability. Additionally, several studies (e.g., [21][22][23]) evaluated the accuracy and limitations of a number of commercial segmentation packages that have been released by CT vendors. To overcome these limitations, we introduce a validation approach that generates 3D realistic phantoms to validate our developed segmentation approach [24,25].…”