Small high-signal lesions posterior to the intracranial vertebral artery incidentally identified by 3D FLAIR: retrospective study of 127 patients



A small, benign high-signal lesion (HSL) posterior to the intracranial vertebral artery (VA) at the foramen magnum is a new entity revealed by a 3D FLAIR sequence. However, this entity has not been sufficiently investigated. We aimed to investigate the MR imaging findings of HSLs posterior to the intracranial VA that were incidentally detected by 3D FLAIR.


We retrospectively evaluated 3717 patients using a 3-T MR unit. HSLs on 3D FLAIR were assessed for prevalence, size, contact with the spinal accessory nerve (SAN), and size changes on follow-up images.


Of 3717 patients, 127 (3.4%) (58 males and 69 females; age, 60.0 ± 18.9 years) showed 142 HSLs posterior to the intracranial VA. In total, 114 patients (89.8%) had a single lesion, whereas 13 patients (10.2%) had multiple lesions. The mean lesion size was 3.8 ± 1.6 mm. All HSLs showed contact with the ipsilateral SAN. Of 69 HSLs that were imaged during follow-up, the size was stable in 91.3% and increased in 8.7%.


HSLs posterior to the intracranial VA were incidentally detected in 3.4% of patients by 3D FLAIR. Our results indicated a possible association between HSLs and SAN. These lesions appear to be benign in etiology and thus would not require any surgical intervention without continuous growth in a short period or relevant signs and symptoms.

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Fast field-echo


High-signal lesion


Spinal accessory nerve


Vertebral artery


Variable flip angle


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Correspondence to Masayuki Maeda.

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The work was funded by grants from the JSPS KAKENHI (Grant no. JP16K10315 and Grant no. JP16K10314).

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The authors declare that they have no conflict of interest.

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All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. For this type of study formal consent is not required.

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For this type of retrospective study formal consent is not required.

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Kogue, R., Maeda, M., Umino, M. et al. Small high-signal lesions posterior to the intracranial vertebral artery incidentally identified by 3D FLAIR: retrospective study of 127 patients. Neuroradiology 60, 591–597 (2018).

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  • Magnetic resonance imaging
  • 3D FLAIR
  • Spinal accessory nerve
  • Foramen magnum
  • Vertebral artery