By

Habib Baluwala

MULTI-MODALITY MEDICAL IMAGE REGISTRATION/FUSION

Medical Image Fusion

• Combines complementary information from different image modalities into a single image

• Revolutionized medical diagnosis

• Whole body Oncology

• Brain

• Cardiology

• Radiotherapy and surgical planning

• Helps to raise clinical value of certain modalities like PET

• Fusion Approaches

• Hybrid imaging – External markers

• Software approach

3

PET (Metabolic info) + CT (Anatomical info) = Fused Image

• Improved anatomical

localization

• Improved staging of

cancer

• Radiotherapy planning

• High spatial

resolution (as high as

0.5 mm)

• Good tissue

contrast

• Differentiate between

benign and malignant

tumours

• Better sensitivity in

the detection of distant

metastases

CT-PET HYBRID SCANNER

PET/MRI HYBRID SCANNERS

• Advantages

• No Ionizing radiation

• Better characterization of soft tissues , bone marrow and spine

• Disadvantages

• Attenuation correction is challenging

• Segmentation-based

• Atlas-based

Hybrid scanners

• Advantages

• More precise co-registration and anatomic localization

• Low computational complexity

• Disadvantages

• Not economical

• Full utilization of the device is seldom achieved

• Software registration might still be needed to compensate for non-rigid registration

Software approach - Registration

• Advantages

• Provides flexibility

• Economical

• Disadvantages

• Time-consuming

• Observer dependent

• Computationally expensive

Similarity function/ Cost function

• Segmentation based approaches

• Statistical voxel intensity-based approaches

• NMI (Normalised Mutual Information)

• MI (Mutual Information)

• NCC (Normalized cross correlation)

• Learning based similarity measures

• KL distance based(Kullback-Leibler distance)

Transformation model

• Optical flow

• Spline based methods

• Fluid registration

• Elastic registration

• Demon’s registration

Visualization of data • Adjacent (side-by-side) displays

• Window displays

• Fade in/out displays

• Checkerboard displays

• Gaze-contingent multi-modality displays

• Hybrid fused displays

• Interleaved video displays

New applications • Interventional radiology using ultrasound

• Ablation

• Biopsy

• Pain Management

• Ultrasound-CT registration

• External- markers based

• Software based

Final Words

• Email : habibbaluwala@gmail.com