1. Balanced Steady-State Free Precession Sequence in the Study of CSF Dynamic Alterations G. Pellicanò, S. Meli, I. Del Seppia, I. Samih Radiology Careggi University Hospital Florence, Italy

2. CSF DYNAMIC: CSF DYNAMIC: - Artifacts and their possible compensation: - Wrong synchrony artifacts - Artifacts secondary to movement - Artifacts due to wrong choice of the VENC

3. - Wrong synchrony artifacts - They manifest either as a wrong reconstruction of the curve or with the impossibility to conclude the acquisition - They are mainly due to patient’s arrythmias, to the low temperature of the hands, or to the presence of nail polish. - In the last two situations, the resolution of the problem may be obtained by the positioning of the PPU on a warmer finger and by removing the nail polish. - in case of arrythmias, almost always it is necessary to suspend the exam CSF DYNAMIC: CSF DYNAMIC:

4. - Artifacts secondary to movement: - Patients undergoing this study are often low compliant and become tired early. - The best system to avoid this kind of artifact, is to favor the study of the CSF dynamic than the execution of the standard exam. - To rapidly perform the exam, also reduce the matrix of acquisition CSF DYNAMIC: CSF DYNAMIC:

5. - Artifacts due to wrong choice of the VENC - They are secondary to the incongruity between the velocity of CSF within the acqueduct and the VENC chosen by the operator - These artifacts manifest with a poor visualization of the acqueduct (VENC too high) or with aliasing (VENC too low) CSF DYNAMIC: CSF DYNAMIC:

6. - Artifacts due to wrong choice of the VENC aliasing bad visualised acqueduct VENC too high VENC too low CSF DYNAMIC: CSF DYNAMIC:

7. - Artifacts due to wrong choice of the VENC - Compensation: - In presence of aliasing the acquisition must be repeated with a higher VENC - In case of poor representation of the acqueduct the VENC must be reduced CSF DYNAMIC: CSF DYNAMIC:

8. - Use of the CEFFET2 sequence : - It is a gradient echo Steady-state sequence with a T2-like contrast - Its construction allows this sequence to be sufficiently sensitive to the movement of protons and to flow, even if slow CSF DYNAMIC: CSF DYNAMIC:

9. STEADY STATE Coherent SS: condition of dynamic balance in which the longitudinal and transverse components of the macroscopic magnetization are simultaneously present z MML absence of RF impulses z MML MMT FA Close RF Impulses (low TR)

10. FID and stimulaed echo Once the steady state is reached, the stimulated echo appears after 2 RF consecutive impulses ; so that the effective ET can be considered 2RT. The detection of the stimulated echo allows to obtain T2 weighted images. Acronymes: CEFFE T2 (Philips) PSIF (Siemens) SSFP (GE) effective ET RT <100 msec RF FID echo stimulated FID

11. CSF DYNAMIC: - Use of the CEFFET2 sequence : - Considering the complex structure of the sequence, it is necessary that the protons receive all the RF and gradient impulses to be able to emit the signal - The parts of the image relative to zones where there is a protonic flow, even if slow, are characterized by a strong signal loss Static CSF Fluent CSF

12. CSF DYNAMIC: - Use of the CEFFET2 sequence : - The features of the sequence make it particularly appropriate for the centering of the acqueduct and for the detection of flow abnormalties within it. - The opportunity to have sub-millimetric slice thickness (3D technique) lead to an extremely precise morphologic imaging of the acqueduct - Advantages

13. CSF DYNAMIC: CSF DYNAMIC: - Use of the CEFFET2 sequence : CEFFET2TSE T2W Arnold-Chiari Malformation

14. CSF DYNAMIC: CSF DYNAMIC: - Use of the CEFFET2 sequence : CEFFET2 Arnold-Chiari Malformation PC 2DQF Acqueduct

15. CSF DYNAMIC: CSF DYNAMIC: - Use of the CEFFET2 sequence : CEFFET2 Arnold-Chiari Malformation A.O. Hinge turbulence PC 2DQF

16. 3rd ventriculo-cisternotomy PC 2DQF CEFFET2 CSF DYNAMIC: CSF DYNAMIC: - Use of the CEFFET2 sequence :

17. If the CSF within the acqueduct appears hyper-intense in the CEFFE T2 sequence, it means that the CSF is static and it becomes useless to acquire subsequently the PC 2DQF sequence. CEFFET2 CSF DYNAMIC: CSF DYNAMIC: - Use of the CEFFET2 sequence :

18. CEFFET2 A further advantage of the CEFFET2 sequence is the opportunity to have an idea about the speed of the CSF flow through the acqueduct and to choose the right VENC during the setting of the phase contrast sequence CSF DYNAMIC: CSF DYNAMIC: - Use of the CEFFET2 sequence :

19. - Although the CEFFET2 sequence results to be very sensitive to minimal CSF motion, it does not allow a quantitative estimation of the signal; indeed, the evaluation of the signal intensity must be considered as subjective and dependent from the personal experience of the operator. - Limits CSF DYNAMIC: CSF DYNAMIC: - Use of the CEFFET2 sequence :

20. - Use of the CEFFET sequence2: - The CEFFE T2 sequence, because of its intrinsic features, should be considered as an excellent tool concenring the setting of the study of the CSF dynamic with PC 2DQF - Conclusions - In our centre, this sequence is considered as the beginning step in the study of CSF dynamic, since its usefulness was demonstrated CSF DYNAMIC: CSF DYNAMIC: