An Overview of
Dr Lohith T G
MMST 2nd year
Indian Institute of Technology
Central Dogma of life
Genetic Revolution Imaging Revolution
• 1953: Watson- • 1972: Computerized
Crick DNA model Tomography
• 1976: Genentech • 1975: Clinical PET
• 1997: Dolly • 1978: Clinical MRI
• 2000: Book of Life • 2000: Fusion Imaging
Molecular Imaging Pioneers
Dr Harvey Herschman Dr Sanjiv Sam Gambhir
“There’s always something unsatisfactory about
studying genes in vitro”
Remote sensing of Cellular processes at molecular
level in-vivo without affecting system.
Early detection of functional abnormalities at
In-vivo imaging of Gene delivery and expression.
Study of pathogenesis of diseases in intact
microenvironments of living systems.
Oncology- Angiogenesis, Apoptosis, Cell tracking
Monitor effectiveness of Gene therapy.
We are curious how we, other people,
animals, etc, look inside…...
… but we don’t like to (be) hurt !
We are also curious
PET, Gamma scintigraphy
Magnetic Resonance Imaging
Magnetic Resonance Spectroscopy
Use of special Imaging Probes with high specificity
Signal Amplification strategies
Sensitive Imaging modalities with high resolution
Mechanisms for molecular imaging at the organ, tissue, cellular, and genetic levels.
Use of PET
High sensitivity (nano to picomolar range)
10,000 targets per cell
F-18, O-15, C-11, N-13, Cu-64, I-124
Poor spatial and Temporal
What area in the brain is responsible for a task?
PET and SPECT imaging enables mapping of
of radio-labeled molecule distributions
Molecular imaging of MDR1 Pgp transport activity in vivo.
MDR1Pgp – Multi drug Resistant membrane receptor P-glycoprotien
PSC 833 – Pgp blocking agent (MDR modulator)
Use of MRI
Magnetic field and radiofrequency pulses
Low sensitivity (milli to micromolar range)
Requires amplification mechanisms
Good spatial and Temporal resolution
Standard Imaging (1.5T) gives 1 mm
Three-dimensional T1-weighted gradient-echo MR imaging
reconstruction (repetition time, 150 msec; echo time, 3.6 msec;
flip angle, 34°; voxel size, 39 3 39 3 78 µm) shows tracking of
immune cells with magnetically labeled lymphocytes homed to a
human glioblastoma tumor (9L tumor model) xenograft in a mouse.
Cell were labeled ex vivo by using a magnetic particle with membrane
translocation signals. Approximately 10,000 cells are distributed
throughout the elongated tumor
Optical coherence tomography
Fluorescence or Luminescence imaging
Luciferase tagged cells
Green fluorescent protein (GFP)
Optical imaging with proteolytically (cathepsin B and H)
activatable near-infrared fluorescent (NIRF) probe.