Constructive Interference in Steady-state Imaging in the Central Nervous System
collicular, and thalamoperforating arteries, in the pontomesencephalic junction, and between the cerebral peduncles (see Figure 10).16
VRS are typically seen as well-defined oval, rounded, or tubular structures, depending on the plane in which they are imaged. They have regular margins, are commonly bilateral, and may be called enlarged when they measure more than 2 mm.17
They can be atypical, presenting in clusters,
or markedly large, causing mass effects, with odd shapes. They can even be misinterpreted as other pathologic processes, most often a cystic neoplasm. Although benign in some situations, dilated VRS can present with hydrocephalus due to compression of the cerebral aqueduct.16
The Vestibular System
CISS can play an important role in cases of sensorial hearing loss and also to study the vestibular system. It delivers fine detail when imaging the semi-circular canals and otolith organs (see Figure 11).17
CISS is extremely useful for evaluating patients with neurocysticercosis (NCC), especially if the cestode is located in the ventricular system or subarachnoid space. CISS is the best single modality to depict the scolex inside the cysticercus cyst, particularly in the first stage of the disease when the cysticercus is antigenically non-viable and neither enhancement nor edema is noted (see Figure 12).
In the second and third stages of NCC, the scolex may or may not be identified. In the fourth (involutional) stage, CISS is not adequate and other MRI sequences are more suitable for characterizing the calcifying cysticercus.18
CISS is useful in patients with hydrocephalus. It is an excellent tool for assessing the cerebral aqueduct because it is capable of demonstrating minute membranes that may be seen in cases of non-communicating hydrocephalus.19
The use of CISS for spinal abnormalities is a more recent development. This sequence can be useful for characterising both intra- and
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2. Scheffler K, Lehnhardt S, Principles and applications of balanced SSFP technique, Eur Radiol, 2003;13:2409–18.
3. Casselman JW, Kuhweide R, Deimling M, et al., Constructive interference in steady state-3DFT MR imaging of the inner ear and cerebellopontine angle, AJNR Am J Neuroradiol, 1993;14:47–57.
4. Girard N, Poncet M, Caces F, et al., Three-dimensional MRI of hemifacial spasm with surgical correlation, Neuroradiology, 1997;39:46–51.
5. Hermans R, Van der Goten A, De Foer B, Baert AL, MRI screening for acoustic neuroma without gadolinium: value of 3DFT-CISS sequence, Neuroradiology, 1997;39:593–8.
6. Held P, Seitz J, Fründ R, et al., MRI detection of olfactory bulb and tract, J Neuroradiol, 2000;27:112–8.
7. Held P, Nitz W, Seitz J, et al., Comparison of 2D and 3D MRI of the optic and oculomotor nerve anatomy, Clin Imaging, 2000;24:337–43.
8. Liang C, Du Y, Lin X, et al., Anatomical features of the cisternal segment of the oculomotor nerve: neurovascular relationships and abnormal compression on magnetic resonance imaging, Neurosurg, 2009;111:1193–200.
extramedullary cystic abnormalities.20 the architecture of arteriovenous fistulas.21
In summary, CISS imaging is useful in the study of CNs, most notably when vascular compression tumors are suspected. CISS may also be of particular use in sensorineural hearing loss, for characterizing the content of a cystic mass, and in cases of NCC. More recently, CISS has proved to be beneficial in spine imaging, especially in cases of intraspinal cystic lesions and arteriovenous malformations. n
9. Satoh T, Omi M, Ohsako C, et al., Visualization of aneurysmal contours and perianeurysmal environment with conventional and transparent 3D MR cisternography, AJNR Am J Neuroradiol, 2005;26:313–8.
10. Yousry I, Moriggl B, Dieterich M, et al., MR anatomy of the proximal cisternal segment of the trochlear nerve: neurovascular relationships and landmarks, Radiology, 2002;223:31–8.
11. Yousry I, Moriggl B, Schmid UD, et al., Trigeminal ganglion and its divisions: detailed anatomic MR imaging with contrast-enhanced 3D constructive interference in the steady state sequences, AJNR Am J Neuroradiol, 2005;26:1128–35.
12. Yoshino N, Akimoto H, Yamada I, et al., Trigeminal neuralgia: evaluation of neuralgic manifestation and site of neurovascular compression with 3D CISS MR imaging and MR angiography, Radiology, 2003;228:539–45.
13. Yousry I, Camelio S, Wiesmann M, et al., Detailed magnetic resonance imaging anatomy of the cisternal segment of the abducent nerve: Dorello’s canal and neurovascular relationships and landmarks, J Neurosurg, 1999;91:276–83.
14. Linn J, Moriggl B, Schwarz F, et al., Cisternal segments of the glossopharyngeal, vagus, and accessory nerves: detailed magnetic resonance imaging-demonstrated anatomy and
neurovascular relationships, J Neurosurg, 2009;110:1026–41.
15. Yousry I, Moriggl B, Schmid UD, et al., Detailed anatomy of the intracranial segment of the hypoglossal nerve: neurovascular relationships and landmarks on magnetic resonance imaging sequences, J Neurosurg, 2002;96:1113–22.
16. Kwee RM, Kwee TC, Virchow-Robin spaces at MR imaging, Radiographics, 2007;27:1071–86.
17. Liang C, Zhang B, Wu L, et al., The superiority of 3D-CISS sequence in displaying the cisternal segment of facial, vestibulocochlear nerves and their abnormal changes, Eur J Radiol, 2010;74(3):437–40.
18. do Amaral LL, Ferreira RM, da Rocha AJ, Ferreira NP, Neurocysticercosis: evaluation with advanced magnetic resonance techniques and atypical forms, Top Magn Reson Imaging, 2005;16:127–44.
19. Kurihara N, Takahashi S, Tamura H, et al., Investigation of hydrocephalus with three-dimensional constructive interference in steady state MRI, Neuroradiology, 2000;42:634–8.
20. Gonçalves FG, Neves PO, Jovem CL, et al., Chronic myelopathy associated to intramedullary cysticercosis, Spine (Phila Pa 1976), 2010;35:E159–62.
21. Ramli N, Cooper A, Jaspan T, High resolution CISS imaging of the spine, Br J Radiol, 2001;74:862–73.
CISS can also be used to study
Figure 12: Sagittal 3D Constructive Interference in Steady-state Reformatted Image at the Level of the Fourth Ventricle Showing an Intraventricular Cysticercus with a Scolex within It (Arrows)
Figure 11: Maximum-intensity Projection of a Normal Membranous Labyrinth Using Constructive Interference in Steady-state Images
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