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Colóquio IFSC - Março/2011 Instrumental basis for an MRI/MRS center dedicated to animal studies A. Tannús – 03/2011 IFSC - USP Colóquio IFSC - Março/2011.

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Presentation on theme: "Colóquio IFSC - Março/2011 Instrumental basis for an MRI/MRS center dedicated to animal studies A. Tannús – 03/2011 IFSC - USP Colóquio IFSC - Março/2011."— Presentation transcript:

1 Colóquio IFSC - Março/2011 Instrumental basis for an MRI/MRS center dedicated to animal studies A. Tannús – 03/2011 IFSC - USP Colóquio IFSC - Março/2011

2 Major items of this talk: Basic Principles; Some methodologies for fast imaging; NMR probes; Digital NMR spectrometer Basics

3 Colóquio IFSC - Março/2011 Major items of this talk: Basic Principles; Some methodologies for fast imaging; NMR probes; Digital NMR spectrometer

4 Colóquio IFSC - Março/2011 Probes: why focus on them? Diversity of anatomies – no single probe for all studies; Studies at the limit of sensitivity; Large number of nuclei of interest; Methodologies requiring dedicated hardware (e. g. split transmit coil ASL – avoid MT); Flexibility of studies – would you touch a US$35k probe to configure it for a new experiment? Better build your own!!

5 Colóquio IFSC - Março/2011 Transmit/receive x split coils: Compromise between uniformity and sensitivity: Compromise between uniformity and sensitivity: We cant get everything with a single coil! We cant get everything with a single coil! Uniform (transmit) coils require more power, consequently are less sensitive (uniform flip angle); Uniform (transmit) coils require more power, consequently are less sensitive (uniform flip angle); Efficient anatomic coils show poor RF field homogeneity – must be used as receive-only – since they present good sensitivity. Efficient anatomic coils show poor RF field homogeneity – must be used as receive-only – since they present good sensitivity.

6 Colóquio IFSC - Março/2011 The problem in Electromagnetism to be solved: surface current in a cylinder Potential Possible resonan t structur e

7 Colóquio IFSC - Março/2011 Transmit RF coils RF reference potential RF coil Tune & match rods

8 Colóquio IFSC - Março/2011 Our best approach: Double Crossed Saddle Tune & match circuit Double crosses (outperforms) the equivalent Birdcage structure

9 Colóquio IFSC - Março/2011 Other structures developed and tested: 8-leg transmit birdcage 16-leg transmit birdcage

10 Colóquio IFSC - Março/2011 Latest developed probe: Receiving coils for rodents – surface coils C CC CMCM CTCT RF out Tune & match circuit on reception

11 Colóquio IFSC - Março/2011 Rodents brain surface coils*: * Tested also as transmit/receive Anesthetics mask Motion restriction

12 Colóquio IFSC - Março/2011 Results: Double Crossed Saddle Actually a 20/30 system for now

13 Colóquio IFSC - Março/2011 Results: Rodents surface coil Actually a 20/30 system for now

14 Colóquio IFSC - Março/2011 Is Manganese contrast possible at 2 T? A B C Coronal images of: control (A, animal 7), 36 h after 60 mg/kg of manganese chloride (B, animal 4,) and after 30 minutes in SE (C, animal 8) – 3D Flash enhances the hippocampus. Answer: YES

15 Colóquio IFSC - Março/ consecutive slices of a control animal showing hippocampus anatomy YES, of course!! And more! Same 3 slices of an animal with 9 months of epileptic life: Notice the size of the ventricles, due to a downsizing hippocampus and other structures not yet associated to the SE. Open field of investigation.

16 Colóquio IFSC - Março/2011 Featuring: active transmit decoupling allows use of any sort of Adiabatic Pulses Passive Signal Cross-over effect TF RF pulse Active TF RF pulse Signal

17 Colóquio IFSC - Março/2011 To come soon: phased array reception coils Preamp Low Z Preamp Low Z Preamp Low Z Preamp Low Z To the 4 BRUKER RECEIVERS

18 Colóquio IFSC - Março/2011 Major items of this talk: Basic Principles; Some methodologies for fast imaging; NMR probes; Digital NMR spectrometer

19 Colóquio IFSC - Março/2011 Digital MR Spectrometer Old fashioned electronics systems could be home made up to the early 90s: Limiting factor: Bus speed. Old fashioned experimental researchers (and newcoming) moved to software development; Electronic devices became highly specific: You cant build what you want, only what the functionality of the devices would allow you!!

20 Colóquio IFSC - Março/2011 Digital MR Spectrometer: Driving forces Commercial systems are expensive and sometimes poor in flexibility; Our Dream System should be something like waking up with a new problem, implementing it at morning, perform the experiments in the afternoon and having the paper ready at night! Our experience with existing systems was a series of frustrations.

21 Colóquio IFSC - Março/2011 Good news from Field Programmable Array Logics devices (FPGAs): Reached speed, density and programmability friendship to allow mere mortals to use them. Modern FPGAs (Statix IV family, Altera and Virtex 6, Xilinx) can accommodate few 4-core Intel CPU (code for that is somewhere over the internet). Development kits come on all flavors, just choose the one that fits your problem (from US$40 to US$9k)!

22 Colóquio IFSC - Março/2011 Our proposal: develop a Digital MRI/MRS Spectrometer in two independent approaches: Using ALTERAs embedded NIOS DSPs (Intellectual Property of ALTERA, we have a working University Agreement); Using our own proprietary MR State Machine instantiated and adapted for all needed spectrometer subsystem modules

23 Colóquio IFSC - Março/2011 NIOS based approach: The event generator subsystem N I O S DSP LOGIC LOGIC Event lines to control other modules Time base To other NIOS Event Program (compiled at PC) FPGA Under development in collaboration with a company (FIT)

24 Colóquio IFSC - Março/2011 MR State Machine approach Different instances of the same concept of our State Machine FPGA

25 Colóquio IFSC - Março/2011 Development workstation

26 Colóquio IFSC - Março/2011 Stratix III development kit

27 Colóquio IFSC - Março/2011 System peripherals Fast A/D and D/A converters (85/125 MHz, 2 Transmit/ receivers for now) Low speed external bus for Gradients Gradients DACs (1us/point, 4 units) High speed external bus/ external SDRAM

28 Colóquio IFSC - Março/2011

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31 Old fashioned experimentalists are now free again!! Please join us on learning, using, teaching your students and convincing others that this new concept of doing electronics is excitingly feasible! Our team: Edson Vidoto Mateus Martins Alberto Tannús Students: Daniel Papoti (DOU) Jackeline Malheiros (DOU) Felipe Coelho (IC) Christofer Bertonha (IC) Tiago Martins (IC) Cintia Silva (DTI) Rafael Martins (ITI) Jorge Sampaio (DTI) Mario Gazziro (DTI) Diogo Queiroz (MES) Cristina Torres (MES) Gustavo Frigieri (PD)

32 Colóquio IFSC - Março/2011 Thank you!


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