Photoacoustic endomicroscopy probe for guiding neurosurgical procedures

Project reference: SIE_27 This project has already been allocated and is no longer available for applications​
First supervisor: Wenfeng Xia 
Second supervisor: Hongbin Liu 

Start date: October 2020

Project summary: Gliomas are the most common type of brain tumour with a grade-dependent prognosis. Glioblastomas (grade 4) have a 5-year survival rate of only 2%. Accurately determining the tumour grade is crucial to optimise patient outcome. However, grading accuracy with stereotactic biopsies is currently limited by inaccurate tumour sampling. During stereotactic brain tumour biopsy, tissue samples are extracted through a needle guided by preoperative stereotactic CT or magnetic resonance imaging (MRI) scans, which cannot reliably determine the right target points. The excised tissue samples are then sent to pathology for a rapid smear examination (~30 min) to obtain a preliminary diagnosis while the patient is still in the theatre. If the samples are extracted from nondiagnostic regions (e.g. from healthy brain tissue), additional biopsies are taken. Each biopsy involves a certain risk of intracranial haemorrhage for the patient. Additionally, each session of the smear examination increases the risk of infection and the costs of theatre time and pathology. In a study with advanced frameless-electromagnetic-navigated-guided biopsy procedures in 371 patients, nondiagnostic tissue samples were provided in 22 cases; repeat biopsy was performed in 6 cases and adverse events that resulted in clinical compromise were observed in 4 patients. Thus, there is an urgent need for novel intraoperative imaging modalities which can visualise cellular-level pathological changes in real-time to guide tumour biopsies.  
 
Project description: This project aims to develop a highly miniaturised, high-resolution, all-optical photoacoustic imaging probe to obtain molecular and microstructural information of tissue from within a stereotactic biopsy needle, so that it can be used to guide interventions in the neurosurgical suite. Photoacoustic imaging is well suited to visualise changes in vascular morphology and blood oxygenation that are known to be associated with tumour development. We will investigate the potential of this novel miniature multi-modal imaging probe to:  

  • Improve the grading accuracy by preventing the extraction of non-tumour tissues;

  • Reduce the number of times a biopsy needle needs to pass through the brain, which is associated with the risk of intracranial haemorrhage;

  • Reduce the theatre time, the risk of infection and the cost of pathology by eliminating the need for the pathological smear examinations; 

  • Facilitate tumour margin assessment during brain tumour resections. 

 
The success of this project will open up new ways to obtain functional, molecular and micro-structure information at cellular level in real-time during minimally invasive procedures across many clinical fields including neurosurgery, oncology, cardiology and fetal medicine. 
 
Objectives

  1. Photoacoustic endomicroscopy probe development. A novel miniature all-optical photoacoustic endomicroscopy probe that will be integrated within a stereotactic needle to acquire functional, molecular and microstructural images from brain tissue during minimally invasive neurosurgical procedures.  

  2. Phantom imaging. The performance of the developed imaging system will be evaluated and optimised with tissue mimicking phantom. 

  3. Human tumour tissue imaging. As a first validation step, imaging with the needle probe will be performed in the neurosurgical suite with human brain tissue ex vivo, immediately before it is submitted for histology. 

 
 

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