Acta Neurochir DOI 10.1007/s00701-014-2109-6
LETTER TO THE EDITOR - NEUROSURGICAL TECHNIQUES
An approach to objective analysis of cerebrospinal fluid flow dynamics with phase-contrast magnetic resonance imaging Murat Ucar & Nil Tokgoz
Received: 15 April 2014 / Accepted: 19 April 2014 # Springer-Verlag Wien 2014
Dear Editor, We read with interest the clinical article written by Wang et al. entitled “Analysis of cerebrospinal fluid flow dynamics and morphology in Chiari 1 malformation with cine phase-contrast magnetic resonance imaging” [8]. The authors performed morphologic and physiologic differences in control subjects and patients with Chiari 1 malformation (C1M) and assessed differences in CSF flow dynamics before and after surgery in patients with C1M using cine phase-contrast magnetic resonance imaging (PCMRI) techniques. They finally found that peak velocity of CSF flow was increased after surgery in C1M patients. I would like to clarify some points and contribute regarding the usefulness of PCMRI in the evaluation and differentiation of C1M along with the related data provided in the literature and our experience. First, it was not clear (due to the small size of the illustrated figure and that the placement of ROIs was not clearly explained) to quantify CSF flow dynamics whether these were drawn on conventional sequences first and then copied onto PCMRI images or drawn onto PCMRI directly. There are some discrepancies in sequence parameters of PCMRI, especially velocity-encoding values and plane direction (in or through). Second, PCMRI is the most widely used technique in the evaluation of C1M. As Wang et al. stated, however, there were big discrepancies between the results of those similar studies [2, 4, 5, 7, 8]. Wang et al. tried to explain those discrepancies
M. Ucar (*) : N. Tokgoz Department of Radiology, School of Medicine, Gazi University Ankara, 06510 Besevler, Ankara, Turkey e-mail: [email protected]
by a small study population. Nevertheless, their findings seem to be somewhat contradictory. While peak velocity along cranial and caudal CSF flow of anterior and posterior cervical subarachnoid space and cranial CSF flow of aqueduct were lower than control subjects and increased after surgery, peak velocity along caudal CSF flows of the aqueduct were higher than the control subject and decreased after surgery. However, when evaluating the CSF flow dynamics, it is crucial to remember that the rules of basic hydrodynamics which is inversely proportional with velocity and diameter. It can be seen that if the diameter decreased, the velocity of the flow must increase. Brinkmann et al. stated that reliable flow quantification is reported to be feasible if the diameter of the lumen is greater than 1.5 mm2 [3]. The PCMRI is the only non-invasive imaging method presently available to quantify CSF flow. However, PCMRI has some major drawbacks, such as being misinterpreted in the presence of turbulent-complex flow or if the velocity encoding value is not correctly chosen. Besides this, since the PCMRI technique is twodimensional, sometimes insufficient or false results may be seen due to partial volume effect and demonstrate only selected plane in a slice. It is possible to obtain multiple cine acquisition in different anatomic locations and imaging planes, but it is not practical. PCMRI also provides physiologic information regarding CSF dynamics. On the other hand, accurate morphologic data cannot be obtained with PCMRI [6]. Three-dimensional, heavily T2-weighted sequences have accepted to provide morphologic data regarding CSF pathways [1]. Finally, morphologic correlation is essentially required for quantification of CSF flow dynamics to evaluate and differentiate C1M. Further comprehensive studies with a
Acta Neurochir
morphologic correlation would yield more information on the CSF flow dynamics in patients with C1M. Conflicts of interest None.
References 1. Algin O, Ozmen E (2012) Heavily T2W 3D-SPACE images for evaluation of cerebrospinal fluid containing spaces. Indian J Radiol Imaging 22(1):74–75 2. Bhadelia RA, Wolpert SM (2000) CSF flow dynamics in Chiari I malformation. AJNR Am J Neuroradiol 21(8):1564 3. Brinkmann G, Harlandt O, Muhle C, Brossmann J, Heller M (2000) Quantification of fluid flow in magnetic resonance tomography: an experimental study of a flow model and liquid flow measurements in the cerebral aqueduct in volunteers. Röfo 172(12):1043–1051
4. Bunck AC, Kröger J, Jüttner A, Brentrup A (2011) Magnetic resonance 4D flow characteristics of cerebrospinal fluid at the craniocervical junction and the cervical spinal canal. Eur Radiol 21(8):1788–1796 5. Haughton VM, Korosec FR, Medow JE, Dolar MT, Iskandar BJ (2003) Peak systolic and diastolic CSF velocity in the foramen magnum in adult patients with Chiari I malformations and in normal control participants. AJNR Am J Neuroradiol 24(2): 169–176 6. Quigley MF, Iskandar B, Quigley ME, Nicosia M, Haughton V (2004) Cerebrospinal fluid flow in foramen magnum: temporal and spatial patterns at MR imaging in volunteers and in patients with Chiari I malformation. Radiology 232(1):229–236 7. Shah S, Haughton V, del Río a M (2011) CSF flow through the upper cervical spinal canal in Chiari I malformation. AJNR Am J Neuroradiol 32(6):1149–1153 8. Wang C-S, Wang X, Fu C-H, Wei L-Q, Zhou D-Q, Lin J-K (2014) Analysis of cerebrospinal fluid flow dynamics and morphology in Chiari I malformation with cine phase-contrast magnetic resonance imaging. Acta Neurochir (Wien) 156(4):707–713
LETTER TO THE EDITOR - NEUROSURGICAL TECHNIQUES
An approach to objective analysis of cerebrospinal fluid flow dynamics with phase-contrast magnetic resonance imaging Murat Ucar & Nil Tokgoz
Received: 15 April 2014 / Accepted: 19 April 2014 # Springer-Verlag Wien 2014
Dear Editor, We read with interest the clinical article written by Wang et al. entitled “Analysis of cerebrospinal fluid flow dynamics and morphology in Chiari 1 malformation with cine phase-contrast magnetic resonance imaging” [8]. The authors performed morphologic and physiologic differences in control subjects and patients with Chiari 1 malformation (C1M) and assessed differences in CSF flow dynamics before and after surgery in patients with C1M using cine phase-contrast magnetic resonance imaging (PCMRI) techniques. They finally found that peak velocity of CSF flow was increased after surgery in C1M patients. I would like to clarify some points and contribute regarding the usefulness of PCMRI in the evaluation and differentiation of C1M along with the related data provided in the literature and our experience. First, it was not clear (due to the small size of the illustrated figure and that the placement of ROIs was not clearly explained) to quantify CSF flow dynamics whether these were drawn on conventional sequences first and then copied onto PCMRI images or drawn onto PCMRI directly. There are some discrepancies in sequence parameters of PCMRI, especially velocity-encoding values and plane direction (in or through). Second, PCMRI is the most widely used technique in the evaluation of C1M. As Wang et al. stated, however, there were big discrepancies between the results of those similar studies [2, 4, 5, 7, 8]. Wang et al. tried to explain those discrepancies
M. Ucar (*) : N. Tokgoz Department of Radiology, School of Medicine, Gazi University Ankara, 06510 Besevler, Ankara, Turkey e-mail: [email protected]
by a small study population. Nevertheless, their findings seem to be somewhat contradictory. While peak velocity along cranial and caudal CSF flow of anterior and posterior cervical subarachnoid space and cranial CSF flow of aqueduct were lower than control subjects and increased after surgery, peak velocity along caudal CSF flows of the aqueduct were higher than the control subject and decreased after surgery. However, when evaluating the CSF flow dynamics, it is crucial to remember that the rules of basic hydrodynamics which is inversely proportional with velocity and diameter. It can be seen that if the diameter decreased, the velocity of the flow must increase. Brinkmann et al. stated that reliable flow quantification is reported to be feasible if the diameter of the lumen is greater than 1.5 mm2 [3]. The PCMRI is the only non-invasive imaging method presently available to quantify CSF flow. However, PCMRI has some major drawbacks, such as being misinterpreted in the presence of turbulent-complex flow or if the velocity encoding value is not correctly chosen. Besides this, since the PCMRI technique is twodimensional, sometimes insufficient or false results may be seen due to partial volume effect and demonstrate only selected plane in a slice. It is possible to obtain multiple cine acquisition in different anatomic locations and imaging planes, but it is not practical. PCMRI also provides physiologic information regarding CSF dynamics. On the other hand, accurate morphologic data cannot be obtained with PCMRI [6]. Three-dimensional, heavily T2-weighted sequences have accepted to provide morphologic data regarding CSF pathways [1]. Finally, morphologic correlation is essentially required for quantification of CSF flow dynamics to evaluate and differentiate C1M. Further comprehensive studies with a
Acta Neurochir
morphologic correlation would yield more information on the CSF flow dynamics in patients with C1M. Conflicts of interest None.
References 1. Algin O, Ozmen E (2012) Heavily T2W 3D-SPACE images for evaluation of cerebrospinal fluid containing spaces. Indian J Radiol Imaging 22(1):74–75 2. Bhadelia RA, Wolpert SM (2000) CSF flow dynamics in Chiari I malformation. AJNR Am J Neuroradiol 21(8):1564 3. Brinkmann G, Harlandt O, Muhle C, Brossmann J, Heller M (2000) Quantification of fluid flow in magnetic resonance tomography: an experimental study of a flow model and liquid flow measurements in the cerebral aqueduct in volunteers. Röfo 172(12):1043–1051
4. Bunck AC, Kröger J, Jüttner A, Brentrup A (2011) Magnetic resonance 4D flow characteristics of cerebrospinal fluid at the craniocervical junction and the cervical spinal canal. Eur Radiol 21(8):1788–1796 5. Haughton VM, Korosec FR, Medow JE, Dolar MT, Iskandar BJ (2003) Peak systolic and diastolic CSF velocity in the foramen magnum in adult patients with Chiari I malformations and in normal control participants. AJNR Am J Neuroradiol 24(2): 169–176 6. Quigley MF, Iskandar B, Quigley ME, Nicosia M, Haughton V (2004) Cerebrospinal fluid flow in foramen magnum: temporal and spatial patterns at MR imaging in volunteers and in patients with Chiari I malformation. Radiology 232(1):229–236 7. Shah S, Haughton V, del Río a M (2011) CSF flow through the upper cervical spinal canal in Chiari I malformation. AJNR Am J Neuroradiol 32(6):1149–1153 8. Wang C-S, Wang X, Fu C-H, Wei L-Q, Zhou D-Q, Lin J-K (2014) Analysis of cerebrospinal fluid flow dynamics and morphology in Chiari I malformation with cine phase-contrast magnetic resonance imaging. Acta Neurochir (Wien) 156(4):707–713
