Article Figures & Data
Figures
- Fig 1.
Representative arterial spin-labeling images for each criterion: extremely decreased perfusion in the whole brain (asterisk, A); patent external carotid circulation and the hollow skull sign (arrows, B), and bright vessel signal intensity around the entry of the carotid artery to the skull (arrows, C). The darker signal intensity in the bilateral parieto-occipital lobes seems to be due to the long transit time exceeding that of the postlabeling decay. Scale units: mL × 100 g−1 × min−1.
- Fig 2.
Representative MR imaging and arterial spin-labeling images in a 50-year-old man with brain death. Sagittal T1WI (A) shows tonsillar impaction in the foramen magnum. Axial T2WI (B) reveals gyral swelling with decreased ventricle size, and DWI (C) shows diffuse hyperintensity involving the whole brain. Contrast-enhanced MRA (D) shows an abrupt cutoff in the bilateral ICAs around the entries of carotid arteries to the skull (arrowheads, D) and the absence of intracranial arterial flow. The ASL images (E–H) satisfy all ASL criteria supporting brain death: extremely decreased perfusion in the whole brain (asterisk, F), bright signal intensity in the ICA around the entry of the carotid artery into the skull suggesting flow stagnation (arrows, G), and patent external carotid circulation and the hollow skull sign (arrowheads, E). Scale units: mL × 100 g−1 × min−1.
- Fig 3.
Representative arterial spin-labeling images in a 75-year-old woman with brain death following an infarct. The images in the upper row were acquired when the patient was admitted with an infarct. The images in the lower row were acquired when the patient was declared brain dead. T2WI (A) shows hyperintense parenchymal swelling in the left MCA territory, and DWI (B) demonstrates increased signal intensity in the corresponding area. TOF MRA (C) reveals total occlusion in the left proximal MCA (arrowhead). The patient also had chronic stenosis in the right proximal ICA. Although cerebral perfusion is severely impaired in the left MCA territory on the ASL image (D), the CBF values in other areas of the brain are preserved. T2WI (E) and DWI (F) performed shortly after the diagnosis of brain death depict diffuse gyral swelling and diffusion hyperintensity, respectively, in the whole brain. TOF MRA (G) shows an abrupt cutoff of the left distal ICA (arrowhead) and absence of intracranial vessels. ASL image (H) demonstrates markedly decreased CBF in the whole brain. Scale units: mL × 100 g−1 × min−1.
- Fig 4.
Representative arterial spin-labeling images in a healthy subject, a patient with brain death, and a patient who had cardiac arrest during an MR imaging examination. These figures show representative ASL and MRA images in a 46-year-old woman as a healthy subject (upper row), a 75-year-old woman with brain death (middle row), and a 20-year-old woman who had sudden cardiac arrest just before the acquisition of ASL images during an MR imaging examination (bottom row). ASL images from the patient with brain death show extremely impaired brain perfusion in the whole brain, bright vessel signal intensity around the level of entry of the carotid artery to the skull (arrowhead), and patent external carotid circulation (arrows) compared with the ASL images from the healthy subject. An MRA image in the patient with brain death (right column of middle row) shows an abrupt cutoff in the left distal ICA (arrow). Although the ASL images from the patient with cardiac arrest also show extremely impaired brain perfusion in the whole brain, there is neither bright vessel signal intensity around the entry of carotid artery to the skull nor patent external carotid circulation. Even though TOF MRA acquired just before the cardiac arrest had normal findings, acquisition of contrast-enhanced MRA after cardiac arrest failed. Scale units: mL × 100 g−1 × min−1. NA indicates not available.
Tables
ASL findings in 5 patients in whom brain death was diagnosed
Case Age (yr) Sex Causes ASL Findings CBF (Mean ± SD, mL × 100 g−1 × min−1) MRA Extremely Decreased Perfusion in the Whole Brain Bright Vessel Signal Intensity around the Entry of Carotid Artery to the Skull (± Level) External Carotid Circulation Hollow Skull Sign 1 71 M Cardiac arrest + +, Rt petrous ICA + + 10.0 ± 2.3 NV 2 60 M Cardiac arrest + +, Bilateral cavernous ICAs + + 8.5 ± 3.2 NA 3 75 F Cerebral infarction + +, Lt petrous ICA + + 7.0 ± 4.5 NV 4 50 M Encephalitis + +, Rt cavernous ICA and Lt petrous ICA + + 7.5 ± 6.4 NV 5 48 F SLE encephalopathy + +, Rt petrous ICA and Lt cavernous ICA + + 6.9 ± 2.8 NA Note:—Lt indicates left; NA, not available; NV, no visualization of intracranial arterial flow; Rt, right; SLE, systemic lupus erythematous; +, present.
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