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Diagnosis and follow-up of posterior inferior cerebellar artery dissection complicated with ischemic stroke assisted by T1-VISTA: a report of two cases
© The Author(s). 2016
Received: 3 March 2016
Accepted: 14 July 2016
Published: 29 July 2016
Volume isotropic turbo spin-echo acquisition (VISTA) is a new method similar to the 3D black-blood imaging method that enables visualization of a intramural hematoma. T1-VISTA has recently been applied in the diagnosis of intracranial arterial dissection. However, the identification of an intramural hematoma in posterior inferior cerebellar dissection (PICA-D) by T1-VISTA has only rarely been reported.
We herein report two patients who suffered from PICA-D complicated with ischemic stroke. Initial magnetic resonance arteriography was not informative, however, T1-VISTA depicted high-intensity signal areas suggesting an intramural hematoma of PICA-D in both cases. The high-intensity signal areas gradually reduced and finally disappeared at 4 months and 5 months after the onset, respectively.
Our cases demonstrate that T1-VISTA was able to assist in the diagnosis and follow-up of PICA-D.
KeywordsMRI PICA dissection Intracranial
Intracranial arterial dissection is an important cause of ischemic stroke, especially in young and middle-aged patients . While vertebral artery dissection (VA-D) is the most frequent among intracranial arterial dissections complicated with ischemic stroke, posterior inferior cerebellar dissection (PICA-D) is rare . Volume isotropic turbo spin-echo acquisition (VISTA) is a new method similar to the 3D black-blood imaging (BBI) method that enables visualization of a mural hematoma and has been applied in the diagnosis of intracranial arterial dissection . Only one paper previously reported the identification of an intramural hematoma of PICA-D using T1-VISTA , whereas no study has been available for its follow-up. In the present report, we describe that T1-VISTA was helpful for the diagnosis and follow-up in our two cases of PICA-D complicated with ischemic stroke.
In these cases, T1-VISTA helped us for the diagnosis and follow-up of PICA-D.
PICA-D complicated with ischemic stroke is rare . As an initial clinical presentation, a subarachnoid hemorrhage is the most common clinical entity following PICA-D, and a cerebral angiogram is performed early in most cases . In the case of ischemic stroke, however, MRA is prioritized, and due to the inability of MRA to depict most of the normal PICA, PICA-D is likely to be overlooked. Recently, BPAS, which can visualize the surface appearance of the vertebrobasilar artery system within the cistern, has been used for the diagnosis of arterial dissection , however, it cannot identify the PICA in some cases. Indeed, we obtained a “pearl and string”-like sign, which reminded us of PICA-D, by the initial MRA in Case 2, while no information regarding PICA was available by MRA or BPAS in Case 1.
The BBI method clearly depicts the structure of the vessel wall by suppressing blood flow signals . Since the 3D-BBI method does not require electrocardiographic triggering, it enables us to shorten the acquisition time and consequently to obtain images with thinner slices of a wider range as compared with 2D imaging. Furthermore, a cross-sectional image of any direction can be reconstructed. T1-VISTA (Phillips Inc., The Netherlands), which is similar to the 3D-BBI method, renders an intramural hematoma as a high-intensity area . T1-SPACE (SIEMENS Inc., Germany) and CUBE-T1 (GE Healthcare, U.S.A.) are akin to T1-VISTA, and some groups have recently reported that these methods are useful for detecting intracranial arterial dissection [7–9]. Although cerebral angiogram findings, such as a “double lumen”, “intimal flap”, “pearl and string sign” and “string sign”, remain the golden standard for diagnosing intracranial arterial dissection, these findings are not always identified on conventional MRA. Thus, an intramural hematoma has been recognized as the definitive finding . Moreover, T1-VISTA is useful in such lesions, due to its short imaging time, non-invasiveness and accuracy in identifying intramural hematomas. Regarding comparison with T1-SPACE and CUBE-T1, since the principle of T1-VISTA is the same as these methods, there might be no especial advantage of T1-VISTA over these methods.
Most of previous reports that identified an intramural hematoma using the 3D-BBI method are about VA-D [7–9]. To the best of our knowledge, only one case has been reported about the detection of an intramural hematoma by PICA-D using the 3D-BBI method , however, no studies about the follow-up findings have been reported. Unlike VA, PICA has many normal variations and is often not visualized on BPAS. In our two cases, it was not possible to identify the appearance of the PICA on BPAS, especially in Case 1 even on MRA, however, we suspected PICA-D due to the high-intensity area on T1-VISTA. In addition, these high-intensity signal areas gradually decreased over time, and finally disappeared in both cases. Because the vascular morphology did not change after these high-intensity signal areas disappeared (data not shown), we suspect that the vessel wall was completely repaired. No consensus has yet been formed regarding the length of time required for the high-intensity signal to disappear. The high-intensity signal areas disappeared at four or five months after the onset in our cases; therefore, we speculate that some time is required to stabilize a dissected portion. In addition, although the precise duration of antithrombotic therapy remains unknown, it may be stopped when the high-intensity signal disappears.
We performed both conventional T1 images and T1-VISTA at some time points in these cases and found that abnormal findings on T1 images mostly appeared later and smaller than those did on T1-VISTA imaging. In Case 1, conventional T1 showed no high-intensity area on admission and at 3 days later, but a pale high-intensity area was documented at the dissected lesion at 19 days after admission. Conventional T1 image was obtained on admission and at 24 days after admission in Case 2, but no high-intensity area was observed in the both time points. Compared with VA-D, the size of PICA-D is smaller, and thus the lesion would be well overlooked by T1 due to its wider slice gap. It seems to be difficult for conventional T1 to detect such a small lesion as compared with T1-VISTA.
In conclusion, T1-VISTA was able to assist in the diagnosis and follow-up of PICA-D complicated with ischemic stroke in these cases.
BBI, black blood imaging; BPAS, basiparallel anatomic scanning; CT, computed tomography; DWI, diffusion weight imaging; MRI, magnetic resonance imaging, PICA-D, Posterior inferior cerebellar dissection, VA-D, vertebral artery dissection, VISTA, volume isotropic turbo spin echo acquisition.
Availability of data and materials
All data and material supporting the conclusions of this article is included within the article. Identifying/confidential have not been and shall not be shared.
KI drafted the manuscript. KI, YS, SS and TU identified the patients and examine the patients serially overtime. HA was involved in imaging acquisition and analyses. TA and TK critically revised the manuscript. HS revised the manuscript and gave the final approval of the version to be published. All authors have read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Written informed consent was obtained from the two patients for publication of this report and any accompanying images. Copies of the written consents are available for review by the Editor-in-Chief of this journal.
Ethics approval and consent to participate
This manuscript was approved by the institutional review board (Koseikan ethics committee, approval number 16-02-3-03), and informed consent for participation was obtained from the patients.
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