2012 Researcher Thanh Binh Nguyen

Diagnostic Accuracy of Perfusion and Diffusion MRI in Patients with Suspected Recurrent High Grade Gliomas

brain cancer researcher thanh binh nguyen

Thanh Binh Nguyen
Ottawa Hospital: Ottawa, Ontario
$24,000.00
 

What does the title mean?

This research will apply imaging technique in patients with treated gliomas to distinguish tumour recurrence from radiation-induced brain injury. The end result aims to show that early diagnosis of tumour recurrence will lead to improved survival as patients could be offered additional treatments sooner.

Project Summary:

Radiation therapy is an important adjunct in the therapy of patients with glioma. Radiation-induced injury of brain parenchyma within the treatment field is a well-recognized phenomenon. However, conventional MR imaging techniques are not always accurate in differentiating recurrent tumour from radiation-induced brain injury, both of which may demonstrate progressive contrast enhancement.

We have developed a novel dynamic contrast enhanced MR imaging technique which can be used to determine how aggressive gliomas are based on the proliferation of abnormal tumour vessels (angiogenesis). The aim of this project is to apply our technique in patients with treated gliomas to distinguish tumour recurrence from radiation-induced brain injury. We plan to recruit 50 patients with high grade gliomas who developed an increase in size of their brain lesion following radiation treatment.

Patients will have conventional MR imaging with contrast, followed by perfusion and diffusion imaging at 3 Tesla. Following surgical biopsy, a neuropathologist will determine the presence of viable tumor cells vs. radiation necrosis in the biopsy area, which will allow correlation with imaging perfusion maps. We hope that early diagnosis of tumour recurrence will lead to improved survival since patients might be offered additional treatments (eg. reresection, gamma knife radiation or chemotherapy).

Final Report:

INTRODUCTION

Currently, high grade glioma treatment consists of combination of surgery, radiation and temozolomide. It is well known that treatment related changes can result in contrast enhancing lesions that closely mimic glioma recurrence on conventional MRI.  This imaging problem is not uncommon as a recent review revealed that 36% of patients with apparent progression of disease seen on MRI have treatment related changes while true progression occurred only in 60% of patients3.

MR perfusion is an imaging technique which provides a more physiologic imaging of these lesions by measuring their blood supply or vascularity. Two perfusion techniques are generally used following injection of a dye: dynamic susceptibility contrast (DSC) perfusion and dynamic contrast enhanced (DCE) perfusion. The two techniques provide different parameters to assess perfusion. In addition to evaluation of the lesion blood volume, DCE perfusion allows assessment of the leakiness of the blood vessels in a lesion (permeability).

OBJECTIVE

We compared the diagnostic accuracy of the two MRI perfusion imaging techniques in differentiating tumor recurrence (TR) from radiation necrosis (RN) in this clinical scenario.

MATERIALS AND METHODS

We consecutively enrolled participants from December 2012 to December 2016. We included high grade glioma (HGG) patients who developed new enhancing lesion on follow up MRI after receiving standard treatment. The latter consisted of surgical resection, standard radiation treatment and temozolomide therapy.  Each patient underwent a MR examination on the 3T scanner including the two perfusion sequences. The lesions were classified as TR and RN based on histopathology or clinical/imaging follow-up.

RESULTS

There were 66 patients and a total of 68 lesions: 37 lesions were classified as predominantly tumour recurrence,  28 lesions were classified as predominantly radiation necrosis and 3 lesions had equal proportions of tumour recurrence and radiation necrosis.  

Patients with tumour recurrence had higher blood volume in the enhancing lesions than patients with radiation necrosis.  However, there is some overlap between the two groups as a few patients with a lesion with high blood volume turned out to have predominantly radiation necrosis at surgery.  

There was no difference in the degree of leakiness of the blood vessels in patients with radiation necrosis and tumour recurrence.

CONCLUSION

MR perfusion imaging allows measurement of the blood volume in an enhancing lesion which is a useful parameter in differentiating tumour recurrence from radiation necrosis.  However, perfusion imaging should be interpreted in the context of conventional MR imaging and diffusion-weighted imaging.

Download the full final report (PDF).

Project Outcome:

A new imaging technique, developed by a Brain Tumour Foundation of Canada grant recipient, is helping doctors more accurately diagnose radiation necrosis from tumour recurrence. 

Radiation is a standard treatment in patients with brain tumours and can cause a brain injury known as radiation necrosis. Both conditions produce a similar lesion in conventional MR images, and often invasive surgery is required to tell the difference between them. 

But now, lead researcher and Ottawa neuroradiologist Dr. Thuah Nguyen says they can diagnose patients with radiation necrosis more accurately without surgery using this new technique, which is available on any MRI machine. 

“Since radiation necrosis can be treated conservatively with steroids, we can avoid unnecessary surgeries for those patients,” says Nguyen.

Also, catching a recurrent tumour more quickly by ruling out radiation necrosis with imaging may also lead to improved survival if patients can be offered additional treatments.   

Thirty-seven patients with high grade gliomas, who had an increase in size of their brain lesion after radiation treatment, participated in the study. Results were published Dec. 7, 2017 in this article in the American Journal of Neuroradiology. 

Dr. Nguyen says none of this research would have been possible without the grants from Brain Tumour Foundation of Canada. 

“I received my first research grant from Brain Tumour Foundation of Canada in 2008. This helped me launch my research career in brain tumour imaging. With my second research grant from Brain Tumour Foundation of Canada in 2012, it allowed me to carry on this project,” he says.  

Nguyen plans to continue discovering more ways to differentiate between radiation necrosis and tumour recurrence using MRI. 

"The goal is to develop clear diagnostic criteria that can be used by any radiologist who sees a new lesion on a surveillance MRI in a patient with a brain tumour treated with radiotherapy."

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