Postprocessing Neuroimaging methods in MRI and PET/MRI

with applications to Multiple Sclerosis and other Neurological diseases

Candidate: D. Poggiali

Tutor: Prof.ssa E. Pegoraro

Supervisor: Prof. P. Gallo

Cosupervisor: Prof. D. Cecchin

Summary:

Introduction to Neuroimaging
State of the art algorithms and pipelines
Cortical Lesion Filling
Glucose PET/MRI in MS
Amyloid PET/MRI in AD

1. Introduction

One of the first brain measurement...

A modern neurological study aims to relate several biomarkers from different sources in order to explain the illness evolution improve prognostic accuracy and optimize the treatment.

A modern research group can have at disposal:

clinical,
imaging,
neuropsychological,
liquor biomarkers

Neuroimaging offers a fecund source of biomarkers

2. State of the art

1. Registration (rigid, affine, nonlinear)

2. Correction (Bias Field, Lesion Filling,

Motion Correction, PVC)

3. Segmentation (Manual, Template-based)

4. Measurement (mean, std over VOIs)

Registration

Correction

Motion Correction

Correction

Partial Volume Correction

Segmentation

Measurements

Cortical Thickness Estimation

Pipelining

3. Cortical Lesion Filling

Lesion filling algorithms in MS try to inpaint T1 hypo-intense WM lesion (about 30% of FLAIR-appearing lesions) as Normal-Appearing White Matter (NAWM).

This procedure has shown to improve:

Segmentation reliability
Cortical Thickness estimation in longitudinal studies.

This procedure has NOT been studied before over Cortical Lesions: only ~15% appear as hypo-intense in T1.

4. Glucose PET/MRI in MS

29 patients, 14 CIS/eRRMS and 15 RRMS underwent a PET/MRI with:

MRI sequences: 3D T1, 3D FLAIR, 3D DIR
18Fdg PET in list-mode

The aim is to study the relationship between:

Cortical Thickness
WM/GM lesion number/volume
aMRGlu

Results are hard to put together!

No correlation was demonstrated between CTh and WM and GM lesion load

No correlation was found between global and regional aMRglu and CTh.

aMRglu correlated with lesion load

Inverse correlation was found between:

the total number of focal lesions (WM+GM lesions) and the global cortical aMRglu (R=-0.36 e p=0.04)
WM lesion volume and number and cortical global aMRglu (R=-0.4 and p=0.02 for both)
GM lesion number with global aMRglu (R=-0.36, p=0.046)

5. Amyloid PET/MRI in AD

86 cases (53 rated negatively and 33 positively by expert amyloid readers) of 18F-Fluorbetaben PET/MRI.

\begin{array}{c} R_1=\frac{PET_1}{PET_1(Cerebcortex)}\\ \\ R_2=\frac{PET_2}{PET_2(Cerebcortex)}\\ \\ SI = R_2- R_1\\ \\ WMR = 100 \frac{PET_2-PET_2(WM)}{PET_1-PET_1(WM)} \end{array}

\begin{array}{c} R_1=\frac{PET_1}{PET_1(Cerebcortex)}\\ \\ R_2=\frac{PET_2}{PET_2(Cerebcortex)}\\ \\ SI = R_2- R_1\\ \\ WMR = 100 \frac{PET_2-PET_2(WM)}{PET_1-PET_1(WM)} \end{array}

WMR

ROC (Receiver Operator Charateristic) curves

Normalization

z-score

Thanks to....

MS Centre Padova

Nuclear Medicine Padova

Neurology Padova

Neuroradiology Unit Padova

Nuclear Medicine Leipzig DE

all patients of course ...

... this audience for the attention!

Some References

DT Chard, JS Jackson, DH Miller, CA Wheeler-Kingshott, Reducing the impact of white matter lesions on automated measures of brain gray and white matter volumes. J Magn Reson Imaging. 2010
SR Das, BB Avants, M Grossman, JC Gee, Registration based cortical thickness measurement, Neuroimage. 2009
C Cobelli, D Foster, G Toffolo,Tracer kinetics in biomedical research, Springer, 2001.
ME Juweid, OS Hoekstra, Positron Emission Tomography, Humana Press, 2011.
CS Patlak, RG Blasberg, Graphical evaluation of blood-to-brain transfer constants from multiple-time uptake data. Generalizations, Journal of Cerebral Blood Flow and Metabolism, 1985.
CL Epstein, ntroduction to the mathematics of Medical Imaging, Second Edition, Siam, 2008
TG Feeman, The mathematics of medical imaging: A beginners guide, Springer, 2010