Table 1

HR-VWI of intracranial aneurysms with 1.5T and 3T scans

Author (year)Sample sizeImaging techniqueVWI enhancement analysisFindings
Hasan (2012)42 25 UIA (13 clipped, 12 observed)3T MRI T1, T2 and TOF MRA pre- and post- (24 and 72 hours)Ferumoxytol-enhanced VWI
  • 3/7 UIA with early signal change within 24 hours were observed and ruptured within 6 months

Matouk (2013)34 5 patients with SAH3T MRI pre- and post-gadSubjective
  • Culprit/primary aneurysm demonstrated thick enhancement; 3/5 patients had multiple aneurysms

Edjlali (2014)28 108 UIA (77 stable, 31 unstable)*3T MRI T1 pre- and T1 post-gadCAWE analysis with multiplanar reconstructions
  • CAWE was more frequent in unstable than stable aneurysms (87% vs 28.5%, p<0.0001)

  • CAWE was associated with unstable status (OR 9.20, p=0.0002)

Coutinho (2015)35 11 patients (DSA-negative SAH)3T MRI T1 pre-, T2 pre-, and T1 post-gadSubjective
  • Mild/focal enhancement suggestive of site of rupture in 7/11 aneurysms

61 UIA3T MRI 3D TOF MRA pre-, black-blood T1W-VISTA pre- and post-gadSubjective
  • Aneurysm size was associated with wall enhancement (OR 2.46 per mm increase, p=0.004)

  • Larger aneurysms showed higher prevalence of wall enhancement: <7 mm=12%, 7–12 mm=71.4%, ≥ 13 mm=100%, p<0.001

30 aneurysms (24 UIA, 6 ruptured)3T MRI TOF MRA pre-, DWI pre-, 3D T1 pre- and post-gadSubjective
  • No correlation between wall enhancement and aneurysm size

  • Strong correlation between wall enhancement and aneurysm symptoms (kappa=0.86)

  • A ruptured MCA avidly-enhancing aneurysm showed significant wall infiltration with lymphocytes and phagocytes

Nagahata (2016)30 144 aneurysms (61 ruptured, 83 UIA)3T MRI T1 pre- and post-gadSubjective
  • Strong enhancement: 73.8% of ruptured and 4.8% of UIA

  • No enhancement: 1.6% of ruptured and 81.9% of UIA

Larsen (2018)14 13 UIA3T MRI T1 pre-, TOF MRA pre-, T1 post-, and TOF MRA post-gadSubjective
  • 5 aneurysms with strong enhancement: inflammatory cell infiltration=4, neovascularization=3, vasa vasorum=2

140 UIA3T MRI TOF MRA pre-, T1 pre- and post-gadSubjective
  • Correlation between wall enhancement and aneurysm size (p<0.001), irregular shape (p=0.003), different locations (p=0.023) and higher PHASES score (p<0.001)

Hudson (2018)16 10 UIA3T MRI T1 pre- and post-gadSubjective
  • Avidly enhancing aneurysms had higher wall thickness (p=0.003) and macrophage infiltration (p=0.048) compared with no- or mild-enhancing aneurysms

Omodaka (2018)29 162 aneurysms (95 UIA: 69 stable, 26 unstable; 67 ruptured)*3T or 1.5T MRI T1 pre-and post-, TOF MRA pre- and post-gadContrast ratio between CAWE and pituitary stalk (CRstalk)
  • The CRstalk ratios were: 0.34 for stable UIAs, 0.54 for unstable UIA sand 0.83 in ruptured aneurysms (p<0.0001)

Shimonaga (2018)15 9 UIA1.5T MRI TOF MRA pre-, T1 pre-, and T1 post-gadSubjective
  • 5 enhancing UIAs showed wall thickening, atherosclerosis, neovascularization, and macrophage infiltration

Backes (2018)23 89 UIA3T MRI 3D TOF MRA, 3D multishot TSE pre- and post-gadSubjective
  • Aneurysm size was a predictor of wall enhancement, with risk ratios: 3–4.9 mm=4.6, 5–6.9 mm=9.4, and ≥7 mm=14.8

  • Location risk ratios: PCOM=3.6, MCA=3.0

Edjlali (2018)31 333 aneurysms, (307 UIA: 276 stable, 31 unstable; 26 ruptured)*3T MRI T1 pre-, T1 post-gad4-grade enhancement: 0=none, 1=focal, 2=thin CAWE, 3=thick (>1 mm) CAWE
  • >1 mm CAWE: sensitivity=61.3%, specificity=84.4%, NPV=94.3% for differentiating stable and unstable UIAs

  • Association between CAWE and aneurysm instability: OR 5.65, p<0.0001

Zhang (2018)50 83 dissecting vertebrobasilar aneurysms3T MRI 3D TOF MRA pre-, T1 pre-, T2 pre- and T1 post-gadSubjective
  • Aneurysm diameter and preoperative wall enhancement were associated with recurrence/progression after endovascular treatment (p<0.05)

Hartman (2019)21 65 UIA (27 stable, 38 unstable)†3T MRI T1 pre- and post-, TOF MRA post-gadSignal intensity analysis per quadrants and qualitative wall thinning
  • Unstable UIAs showed more enhancement: 42.1% vs 14.8%, p=0.022; greater extent of enhancement: 2.9 vs 2.2 quadrants, p=0.063; and wall thinning 9.2% vs 0%, p=0.044 than stable UIAs

Wang (2019)25 88 UIA3T MRI 3D TOF MRA pre-, black-blood T1W-VISTA pre- and post-gadSubjective
  • Correlation between wall enhancement and irregular shape: OR 12.5, p=0.02; and high depth/neck width aspect ratio: OR 32.9, p=0.01

  • Aspect ratio cut-off=1.05: sensitivity=60%, specificity=91.3%

Wang (2019)32 89 UIA: 31 symptomatic, 58 asymptomatic3T MRI 3D TOF MRA pre-, T1 pre- and post-gadSignal intensity measured in aneurysm neck, body and dome. ER calculated as (SImax − SIpre)/SIpre×100%
  • ER was associated with symptomatic UIA (OR 29.4, p<0.001)

  • ER threshold=60.5%: sensitivity=90.3%, specificity=87.9%

Quan (2019)18 54 UIA (9 histology specimens)3T MRI fat-suppressed 3D T1 pre- and T1 post-gadSubjective
  • Correlation between wall enhancement and irregular shape (p=0.021)

  • Focal enhancement suggestive of atherosclerotic plaques within the aneurysmal wall (p=0.007)

  • Gray rows highlight studies with histological correlate.

  • *Stable aneurysm defined as incidental/asymptomatic and non-evolving on serial 6-month follow-up.

  • †Stable aneurysm defined as PHASES score ≤3.

  • CAWE, circumferential aneurysm wall enhancement; CTA, CT angiography; DSA, digital substraction angiography; DWI, diffusion-weighted imaging; ER, enhancement ratio; MCA, middle cerebral artery; MRA, magnetic resonance angiography; MRI, magnetic resonance imaging; NPV, negative predictive value; PCOM, posterior communicating artery; SAH, subarachnoid hemorrhage; SI, signal intensity; TOF, time-of-flight; TSE, turbo spin-echo; UIA, unruptured intracranial aneurysm; VISTA, volume isotropic turbo-spin-echo acquisition; VWI, vessel wall imaging.