Measurement of cerebral perfusion with arterial spin labeling: Part 2. Applications

Brown, Gregory G.; Clark, Camellia P.; Liu, Thomas T.

doi:10.1017/s1355617707070634

Cited by 92 publications

(72 citation statements)

References 84 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…A timely multicentre reproducibility study showed promising results [42], providing the reliability needed to proceed to clinical studies. A recent review paper [43] summarises major research areas, which include cerebrovascular disease, dementia, oncology and studies of normal brain function. One particular area of growth and interest is in the use of ASL for functional imaging, important for clinical studies where neurovascular coupling may be altered.…”

Section: Endogenous Contrast Technique: Arterial Spin Labellingmentioning

confidence: 99%

Dynamic contrast-enhanced imaging techniques: CT and MRI

O’Connor¹,

Tofts²,

Miles³

et al. 2011

BJR

172

121

View full text Add to dashboard Cite

ABSTRACT. Over the last few decades there has been considerable research into quantifying the cerebral microvasculature with imaging, for use in studies of the human brain and various pathologies including cerebral tumours. This review highlights key issues in dynamic contrast-enhanced CT, dynamic contrast-enhanced MRI and arterial spin labelling, the various applications of which are considered elsewhere in this special issue of the British Journal of Radiology. The tumour microvasculature can readily be imaged using X-ray, CT and MRI techniques. This review concentrates on three main methods. Dynamic contrast-enhanced CT (DCE-CT) and dynamic contrastenhanced MRI (DCE-MRI) are well-established techniques, where data acquisition and analysis are comparable despite inherent differences in signal production and mechanism of tissue contrast enhancement (reviewed in [1,2]). Although they can be performed on conventional clinical scanners, they require specialist image analysis to extract biomarkers of tumour vascular function. In distinction, arterial spin labelling (ASL) offers a highly specific method of measuring cerebral perfusion without exogenous contrast agent (CA) administration, but is at present a research technique. The practical applications of these techniques are considered elsewhere in this special issue. Basic principles of dynamic contrast-enhanced imagingDCE imaging describes the acquisition of a baseline image(s) without contrast enhancement followed by a series of images acquired over time after an intravenous bolus of conventional CA. The presence of CA within cerebral blood vessels and tissues affects measured X-ray attenuation on CT in a linear fashion and the calculated signal intensity on MRI in a non-linear manner. Thus, the temporal changes in contrast enhancement effectively provide a time-concentration curve, which can be analysed to quantify a range of physiological parameters that indicate the functional status of the vascular system within tumours and adjacent tissues. These parameters reflect the two-compartment pharmacokinetics exhibited by CA, comprising intravascular and extravascular components. During the first-pass of the CA through the circulation (typically 45-60 s after injection), CA is predominantly intravascular allowing evaluation of perfusion (i.e. blood flow per unit volume or mass of tissue), relative blood volume (rBV) and mean transit time. During the subsequent 2-10 min, there is increasing passage of CA into the extravascular space, and imaging during this delayed phase enables measurement of vascular permeability and relative extravascular volume. DCE-CT image acquisition protocolsA number of distinct DCE-CT techniques have been developed, reflecting the different analysis methodologies adopted by commercial software packages for perfusion CT. The main acquisition factors to be considered are summarised in Table 1. For DCE-CT, the need to keep the radiation burden as low as practicable is a constraint on the total number of images acquired and the X-ray exposure ...

show abstract

Section: Endogenous Contrast Technique: Arterial Spin Labellingmentioning

confidence: 99%

Dynamic contrast-enhanced imaging techniques: CT and MRI

O’Connor¹,

Tofts²,

Miles³

et al. 2011

BJR

172

121

View full text Add to dashboard Cite

show abstract

“…4,5 CASL measures of cerebral perfusion are highly accurate in detecting lesion laterality in temporal lobe epilepsy, stenotic-occlusive disease, and brain tumors. 19,20 Among patients with cerebrovascular disease, CASL CBF has excellent concurrent validity when correlated with CBF measured by positron emission tomography 21,22 or with dynamic susceptibilityweighted magnetic resonance. 19 A correlative study of CASL with CO 2 PET validation demonstrated that quantification of CBF using CASL is feasible and reasonable in patients with chronic occlusive cerebrovascular disease, even when employed in a rou- tine clinical setting.…”

Section: Figure 1 Anatomic and Perfusion Mr Imagesmentioning

confidence: 99%

“…19,20 Among patients with cerebrovascular disease, CASL CBF has excellent concurrent validity when correlated with CBF measured by positron emission tomography 21,22 or with dynamic susceptibilityweighted magnetic resonance. 19 A correlative study of CASL with CO 2 PET validation demonstrated that quantification of CBF using CASL is feasible and reasonable in patients with chronic occlusive cerebrovascular disease, even when employed in a rou- tine clinical setting. The long transit time, however, may lead to CBF underestimation on the occluded side.…”

Section: Figure 1 Anatomic and Perfusion Mr Imagesmentioning

confidence: 99%

Vasoreactivity and peri-infarct hyperintensities in stroke

Zhao

Alsop²,

Abduljalil³

et al. 2009

Neurology

View full text Add to dashboard Cite

Objective: It is unknown if impaired cerebral vasoreactivity recovers after ischemic stroke, and whether it compromises perfusion in regions surrounding infarct and other vascular territories. We investigated the regional differences in CO 2 vasoreactivity (CO 2 VR) and their relationships to peri-infarct T2 hyperintensities (PIHs), chronic infarct volumes, and clinical outcomes. Methods:We studied 39 subjects with chronic large middle cerebral artery territory infarcts and 48 matched controls. Anatomic and three-dimensional continuous arterial spin labeling imaging at 3-Tesla MRI were used to measure regional cerebral blood flow (CBF) and CO 2 VR during normocapnia, hypercapnia, and hypocapnia in main arteries distributions. Results:Stroke patients showed a significantly lower augmentation of blood flow at increased CO 2 but greater reduction of blood flow with decreased CO 2 than the control group. This altered vasoregulatory response was observed both ipsilateral and contralateral to the stroke. Lower CO 2 VR on the stroke side was associated with PIHs, greater infarct volume, and worse outcomes. The cases with PIHs (n ϭ 27) had lower CBF during all conditions bilaterally (p Ͻ 0.0001) compared to cases with infarct only. Conclusions: Perfusion augmentation is inadequate in multiple vascular territories in patients withlarge artery ischemic infarcts, but vasoconstriction is preserved. Peri-infarct T2 hyperintensities are associated with lower blood flow. Strategies aimed to preserve vasoreactivity after an ischemic stroke should be tested for their effect on long-term outcomes. Neurology ® 2009;72:643-649 GLOSSARY ACA ϭ anterior cerebral artery; ADC ϭ apparent diffusion coefficient; BP ϭ blood pressure; CASL ϭ continuous arterial spin labeling; CBF ϭ cerebral blood flow; CO 2 VR ϭ CO 2 vasoreactivity; DWI ϭ diffusion-weighted image; FLAIR ϭ fluidattenuated inversion recovery; FOV ϭ field of view; GM ϭ gray matter; LDL ϭ low-density lipoprotein; MCA ϭ middle cerebral artery; MP-RAGE ϭ magnetization prepared rapid gradient echo; mRS ϭ modified Rankin Scale; NIHSS ϭ NIH Stroke Scale; PCA ϭ posterior cerebral artery; PIHs ϭ peri-infarct T2 hyperintensities; TE ϭ echo time; TI ϭ inversion time; TR ϭ repetition time; WBC ϭ white blood cell; WM ϭ white matter.Perfusion in regions surrounding ischemic areas is associated with recovery.1 Cerebral vasoregulation maintains steady cerebral blood flow (CBF) in response to changes in CO 2 , but systemic blood pressure (BP) is compromised by microvascular disease and further impaired by stroke.2 It is not known whether cerebral vasoregulation recovers in older people with ischemic stroke or whether vascular beds in the infarcted hemisphere remain challenged to maintain perfusion. Unrecognized brain infarctions and peri-infarct hyperintensities (PIHs) are common MRI findings during later stages after stroke.3 It is unknown if the distribution of impaired vasoreactivity extends beyond the infarct region into surrounding gray and white matter and compromises perfusion i...

show abstract

“…14 The advantages of arterial spin-labeling (ASL) compared with conventional perfusion techniques include repeatability, absolute quantification, and the avoidance of intravenous contrast administration. 15,16 We performed a retrospective analysis of MR imaging examinations including ASL perfusion in patients with an indication of headache from the past 12 months and identified 11 clinical patients with a history of migraine headache.…”

mentioning

confidence: 99%

Migraine Associated Cerebral Hyperperfusion with Arterial Spin-Labeled MR Imaging

Pollock¹,

Deibler²,

Burdette³

et al. 2008

AJNR Am J Neuroradiol

View full text Add to dashboard Cite

SUMMARY:We present a case series demonstrating abnormal regional cerebral hyperperfusion associated with migraine headache using arterial spin-labeling (ASL). In 3 of 11 patients, regional cortical hyperperfusion was demonstrated during a headache episode that corresponded to previous aura symptoms. Migraine is a common condition affecting 12% of the United States population per year.1 Migraines classically present with unilateral debilitating, painful headaches associated with photophobia, phonophobia, nausea, and vomiting. Less than 30% of migraines are preceded by auras, or focal neurologic deficits. Most commonly, the neurologic deficits are visual, but sensory and motor deficits can also occur. The pathophysiology of a migraine is complex and is not completely understood. The vascular theory proposes that the migraine aura is associated with vasoconstriction and the subsequent headache is associated with vasodilation and hyperperfusion.3,4 The second theory is that a contiguous wave of neuronal depression spreads through the cortex causing the aura symptoms.5-10 The vascular changes have been evaluated with nuclear medicine studies including single-photon emission CT and positron-emission tomography as well as blood oxygen level-dependent functional MR imaging and T2* dynamic susceptibility contrast (DSC) MR perfusion imaging. 3,8,9,[11][12][13] These methods are limited in the evaluation of the patient with migraine because of the dynamic nature of the perfusion abnormalities.Spin tag perfusion imaging is an MR imaging method that measures quantitative cerebral blood flow (CBF).14 The advantages of arterial spin-labeling (ASL) compared with conventional perfusion techniques include repeatability, absolute quantification, and the avoidance of intravenous contrast administration. 15,16 We performed a retrospective analysis of MR imaging examinations including ASL perfusion in patients with an indication of headache from the past 12 months and identified 11 clinical patients with a history of migraine headache. We present the 3 patients with migraine-associated regional cerebral hyperperfusion corresponding to the clinical presentation. Case Reports Patient 1A 55-year-old woman with a history of hemiplegic migraines presented with new-onset right frontal headache, left-sided numbness, weakness, and dysarthria. The patient took prochlorperazine (Compazine) at home without relief of her symptoms. We performed cerebral MR imaging 6 hours after onset of symptoms using our standard stroke protocol including conventional sequences and ASL perfusion. Conventional MR imaging sequences demonstrated subtle sulcal effacement and mild edema in the right frontal cortex without evidence of diffusion abnormality (Fig 1).We generated quantitative CBF maps using quantitative imaging of perfusion and a single subtraction with thin-section inversion time (TI) 1 periodic saturation with a flow-sensitive alternating inversion recovery sequence as described previously.17 This sequence generates 60 tag and control image pairs. Imag...

show abstract

Measurement of cerebral perfusion with arterial spin labeling: Part 2. Applications

Cited by 92 publications

References 84 publications

Dynamic contrast-enhanced imaging techniques: CT and MRI

Dynamic contrast-enhanced imaging techniques: CT and MRI

Vasoreactivity and peri-infarct hyperintensities in stroke

Migraine Associated Cerebral Hyperperfusion with Arterial Spin-Labeled MR Imaging

Contact Info

Product

Resources

About