Simpósio PICMI - Outubro /2011

1. Simpósio PICMI - Outubro/2011 A Ressonância Magnética como um método de aferição da PIC Alberto Tannús CIERMag – IFSC - USP

2. Major items of this talk: • Basic ideas for verifying ICP; • MRI methodologies; • Existing facility

3. Changes in morphology: •  An increased ICP would show as enlarged ventricles, which can be seen in the transverse sectioning; • Optic Nerve Sheath Diameter (ONSD) – US -> MRI: Increased ICP is transmitted through the cerebrospinal fluid surrounding the optic nerve, causing distention of the optic nerve sheath diameter (http://noninvasiveicp.com/node/47) • retro-bulbar optic nerve sheath diameter (ONSD) above 5.82mm predicts raised ICP in 90% of cases (http://www.sciencedaily.com/releases/2008/09/080910210531.htm)

4. From Geeraerts Tet al., Crit Care. 2008;12(5):R114 

5. Changes in morphology continued: •  Measurement of intracranial compliance (ICC) with dynamic magnetic resonance imaging (MRI) of blood and cerebrospinal fluid (CSF) flows to and from the brain (research of N J Alperin from University of Illinois at Chicago); (Alperin et al Acta NeurochirurgicaSupplementum, 2005, Volume 95, Part 4, 191-193) • MR imaging of the optic nerves and pituitary gland provided important clues for the diagnosis of idiopathic intracranial hypertension and showed a return to normal appearance after normalization of CSF pressure (Suzuki et al, AJNR Am J Neuroradiol 22:196–199, January 2001)

6. Flow and perfusion methods: •  Cerebral Blood Flow and ICP: results demonstrated that CBF values span over a much narrower range as compared with ICP. It means no correlation, due to self regulatory mechanism of TCBF. (Alperin et al, ib.) • Gives rise to correlations of blood flow (velocity and profile) with TCBF; (one of our proposals.)

7. Major items of this talk: • Basic ideas for verifying ICP; • MRI methodologies; • Existing facility

8. Morphology: • Conventional imaging methods – RARE, TSE, IRSE etc.; • Fast Imaging methods – EPI; • Short TE methods – UTE, ZTE etc.; • Flow and diffusion: • Diffusion weighted imaging – DWI; • Image phase map for flow measurements; • Imaging methods for transverse velocity profile; • Spin Labeling for CBF and TCBF estimates – ASL, CASL, PASL.

9. Major items of this talk: • Basic ideas for verifying ICP; • MRI methodologies; • Existing facility

10. CIERMag (Centro de Imagens e Espectroscopia in vivo por RM): • One 2.0 Tesla 31 cm horizontal magnet running with a Bruker electronics (Avance III/ Paravision 5.1); • Capable to perform ANY MRI/MRS methodology; • MRI and MRS Probes for small rodents and small primates (up to 450g), and for different nuclear species on demand; • Pending conclusion of special facility to accommodate a 4.7 Tesla 33 cm bore horizontal magnet; • Pending conclusion of the fully Digital MRI/MRS Spectrometer to operate this and other systems (ToRM 15 Project);

11. CITESC (Ciencia, Inovação e TecnologiaemSaúde, unidade de São Carlos): • One 1.5 Tesla whole body scanner with patient/ volunteer agenda (clinical research); • One 1.5 Tesla (or one 0.35 Tesla) whole body scanner for technological development (may be used for clinical experiments on new methodologies involving hardware development);

12. 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!!

13. Our best approach: Double Crossed Saddle Tune & match circuit “Double crosses” (outperforms) the equivalent Birdcage structure

14. Latest developed probes:Receiving coils for rodents – surface coils C CM C C CT RFout Tune & match circuit on reception

15. Rodents brain surface coils*: Anesthetics mask Motion restriction * Tested also as transmit/receive

16. Results: Double Crossed Saddle Actually a 20/31 system for now

17. Thank you!