Simpósio PICMI - Outubro/2011
A Ressonância Magnética como
um método de aferição da PIC
Alberto Tannús
CIERMag – IFSC - USP
Simpósio PICMI - Outubro/2011
Major items of this talk:
 Basic ideas for verifying ICP;
 MRI methodologies;
 Existing facility
Simpósio PICMI - Outubro/2011
 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/2008/09/08
0910210531.htm)
Simpósio PICMI - Outubro/2011
From Geeraerts T et al., Crit Care. 2008;12(5):R114
Simpósio PICMI - Outubro/2011
 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 Neurochirurgica Supplementum, 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)
Simpósio PICMI - Outubro/2011
 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.)
Simpósio PICMI - Outubro/2011
Major items of this talk:
 Basic ideas for verifying ICP;
 MRI methodologies;
 Existing facility
Simpósio PICMI - Outubro/2011
 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.
Simpósio PICMI - Outubro/2011
Major items of this talk:
 Basic ideas for verifying ICP;
 MRI methodologies;
 Existing facility
Simpósio PICMI - Outubro/2011
 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);
Simpósio PICMI - Outubro/2011
 CITESC (Ciencia, Inovação e Tecnologia em Saúde, 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);
Simpósio PICMI - Outubro/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!!
Simpósio PICMI - Outubro/2011
Our best approach: Double Crossed Saddle
Tune & match circuit
“Double crosses” (outperforms) the
equivalent Birdcage structure
Simpósio PICMI - Outubro/2011
Latest developed probes:
Receiving coils for rodents – surface coils
C
CM
CT
C
C
RFout
Tune & match circuit
on reception
Simpósio PICMI - Outubro/2011
Rodents brain surface coils*:
Anesthetics
mask
Motion
restriction
* Tested also as transmit/receive
Simpósio PICMI - Outubro/2011
Results: Double Crossed Saddle
Actually a 20/31
system for now
Simpósio PICMI - Outubro/2011
Thank you!