Contribution of advanced MRI to the diagnosis of giant tumefactive perivascular spaces

Background Giant tumefactive perivascular spaces (PVSs) are uncommon benign cystic lesions. They can imitate cystic neoplasms. Purpose To evaluate the contribution of advanced neuro magnetic resonance imaging (MRI) techniques in the diagnosis of giant tumefactive PVSs and to further characterize these unusual cerebral lesions. Material and Methods The MRI scans of patients with tumefactive PVS diagnosed between 2010 and 2019 were retrospectively reviewed. All imaging studies included three plane conventional cerebral MRI sequences as well as precontrast 3D T1 MPRAGE, post-gadolinium 3D T1 acquisitions, sagittal plane 3D T2 SPACE, diffusion-weighted imaging, and time-of-flight (TOF) angiography. Some patients received perfusion MR, MR spectroscopy, diffusion tensor imaging (DTI), and contrast-enhanced TOF MR angiography. Results A perforating vessel was demonstrated in 16 patients (66.7%) by TOF imaging. In four patients, there were intracystic vascular collaterals on contrast-enhanced TOF MR angiography. Septal blooming was observed in four patients in susceptibility-weighted imaging. On perfusion MR, central hyperperfusion was observed in four patients, and peripheral hyperperfusion was observed in one patient. On MR spectroscopy, choline increase was observed in two patients, and there was a lactate peak in three patients, and both a choline increase and lactate peak in one patient. On DTI, there was fiber distortion in five patients and fiber deformation in one patient. Conclusion Advanced MRI techniques and 3D volumetric high-resolution MRI sequences can provide a valuable contribution to the diagnosis and can be successfully used in the management of these lesions.

Bilateral typeIIpersistent proatlantal intersegmental artery: a rare variant of persistent carotid-vertebrobasilar anastomoses

The persistent proatlantal intersegmental artery is a rare variant of persistent carotid-vertebrobasilar anastomoses, especially their bilateral presence is rarer. We report a case of bilateral typeII persistent proatlantal intersegmental artery. The absence of bilateral vertebral arteries was incidentally noted on neck ultrasound examination. Subsequent time-of-flight MR angiography confirmed this. The bilateral typeIIpersistent proatlantal intersegmental artery arose from the cervical external carotid artery, penetrated the C1 transverse foramen, entered the skull via the foramen magnum, and joined the lower portion of the basilar artery.

Can intracranial time-of-flight-MR angiography predict extracranial carotid artery stenosis?

Objectives Extracranial stenosis of the internal carotid artery (ICA) is an important cause of ischemic stroke and transient ischemic attack (TIA). It can be diagnosed using contrast-enhanced CT or MR angiography (MRA) as well as Doppler ultrasound. In this study, we assessed the diagnostic value of intracranial time-of-flight (TOF) MRA to predict extracranial ICA stenosis (ICAS). Methods We retrospectively analyzed consecutive patients with acute ischemic stroke or TIA and middle- (50–69%) or high-grade (70–99%) unilateral extracranial ICAS according to NASCET criteria assessed by ultrasound between January 2016 and August 2018. The control group consisted of patients without extracranial ICAS. Intraluminal signal intensities (SI) of the intracranial ICA on the side of the extracranial stenosis were compared to the contralesional side on TOF-MRA source images. SI ratios (SIR) of contralesional:lesional side were compared between groups. Results In total, 151 patients were included in the main analysis. Contralesional:lesional SIR in the intracranial C4-segment was significantly higher in patients with ipsilateral extracranial ICA stenosis (n = 51, median 74 years, 57% male) compared to the control group (n = 100, median 68 years, 48% male). Mean SIR was 1.463 vs. 1.035 (p < 0.001) for right-sided stenosis and 1.362 vs. 1.000 (p < 0.001) for left-sided stenosis. Receiver-operating characteristic curve demonstrated a cut-off value of 1.086 for right-sided [sensitivity/specificity 75%/81%; area under the curve (AUC) 0.81] and 1.104 for left-sided stenosis (sensitivity/specificity 70%/84%; AUC 0.80) in C4 as a good predictor for high-grade extracranial ICAS. Conclusions SIR on TOF-MRA can be a marker of extracranial ICAS.