A Comparative Study of Automated Segmentation Methods for Use in a Microwave Tomography System for Imaging Intracerebral Hemorrhage in Stroke Patients

Abstract

Microwave technology offers the possibility for pre-hospital stroke detection as we have previously demonstrated using non-imaging diagnostics. The focus in this paper is on image-based diagnostics wherein the technical and computational complexities of image reconstruction are a challenge for clinical realization. Herein we investigate whether information about a patient's brain anatomy obtained prior to a stroke event can be used to facilitate image-based stroke diagnostics. A priori information can be obtained by segmenting the patient's head tissues from magnetic resonance images. Expert manual segmentation is presently the gold standard, but it is laborious and subjective. A fully automatic method is thus desirable. This paper presents an evaluation of several such methods using both synthetic magnetic resonance imaging (MRI) data and real data from four healthy subjects. The segmentation was performed on the full 3D MRI data, whereas the electromagnetic evaluation was performed using a 2D slice. The methods were evaluated in terms of: i) tissue classification accuracy over all tissues with respect to ground truth, ii) the accuracy of the simulated electromagnetic wave propagation through the head, and iii) the accuracy of the image reconstruction of the hemorrhage. The segmentation accuracy was measured in terms of the degree of overlap (Dice score) with the ground truth. The electromagnetic simulation accuracy was measured in terms of signal deviation relative to the simulation based on the ground Q. Mahmood et al. 153 truth. Finally, the image reconstruction accuracy was measured in terms of the Dice score, relative error of dielectric properties, and visual comparison between the true and reconstructed intracerebral hemorrhage. The results show that accurate segmentation of tissues (Dice score = 0.97) from the MRI data can lead to accurate image reconstruction (relative error = 0.24) for the intracerebral hemorrhage in the subject's brain. They also suggest that accurate automated segmentation can be used as a surrogate for manual segmentation and can facilitate the rapid diagnosis of intracerebral hemorrhage in stroke patients using a microwave imaging system.

Microwave technology for detecting traumatic intracranial bleedings: tests on phantom of subdural hematoma and numerical simulations

“…In the future, it may also be possible to image the brain and visualize stroke and TBI lesions [ 11 , 12 , 14 , 19 , 21 , 22 , 32 , 36 , 37 ]. Contemporary systems do not provide detailed anatomical images compared to CT, but may still be valuable for detection of intracranial hemorrhage, see, e.g., [ 21 , 22 ].…”

“…Contemporary systems do not provide detailed anatomical images compared to CT, but may still be valuable for detection of intracranial hemorrhage, see, e.g., [ 21 , 22 ]. Current imaging algorithms are not sufficiently fast to enable prehospital use without use of a priori information [ 19 ]. Mobashsher et al.…”

On-site Rapid Diagnosis of Intracranial Hematoma using Portable Multi-slice Microwave Imaging System

“…Unfortunately, time is critical for ICH affected patients123456. Nevertheless, the imaging resolution of radar based imaging system34 (less than 10  mm ) is comparable to the tomography based head imaging system35363839 (5–7  mm ). This resolution is higher when compared to other portable imaging modalities910111213.…”

“…At the same time, these issues can potentially jeopardise the continuous monitoring of the patient upon initial diagnosis. The reported automated head imaging prototypes353637383940 use complex imaging system infrastructure involving matching liquids and relatively bulky switching network3536373839 in order to improve precision and accelerate data acquisition. However, they are designed for narrow band operation and require huge time (from tens of minutes to hours40 depending on the required imaging accuracy) for image reconstruction, which is often shortened by using a dedicated supercomputer353839.…”

Early Brain Stroke Detection Using Flexible Monopole Antenna

“…Alqadami et al used a flexible and wideband 8-element array antenna with a dimension of 85 × 60 × 4 mm 3 based on a multilayer PDMS polymer substrate to detect brain stroke with a head imaging system [10]. Above discussed investigations take time for effective image reconstruction [11] and have strong multipath reflections due to array configuration [12,13]. All these techniques used rigid substrates except Bashri et al [9] and Alqadami et al [10].…”