title: Cerebral hemodynamics and pseudo-continuous arterial spin labeling considerations in adults with sickle cell anemia.
abstract: Sickle cell anemia (SCA) is a genetic disorder resulting in reduced oxygen carrying capacity and elevated stroke risk. Pseudo-continuous arterial spin labeling (pCASL) measures of cerebral blood flow (CBF) may have relevance for stroke risk assessment; however, the effects of elevated flow velocity and reduced bolus arrival time (BAT) on CBF quantification in SCA patients have not been thoroughly characterized, and pCASL model parameters used in healthy adults are often applied to patients with SCA. Here, cervical arterial flow velocities and pCASL labeling efficiencies were computed in adults with SCA (n = 19) and age- and race-matched controls without sickle trait (n = 7) using pCASL in sequence with phase contrast MR angiography (MRA). Controls (n = 7) and a subgroup of patients (n = 8) also underwent multi-post-labeling-delay pCASL for BAT assessment. Mean flow velocities were elevated in SCA adults (velocity = 28.3 ± 4.1 cm/s) compared with controls (velocity = 24.5 ± 3.8 cm/s), and mean pCASL labeling efficiency (α) was reduced in SCA adults (α = 0.72) relative to controls (α = 0.91). In patients, mean whole-brain CBF from phase contrast MRA was 91.8 ± 18.1 ml/100 g/min, while mean pCASL CBF when assuming a constant labeling efficiency of 0.86 was 75.2 ± 17.3 ml/100 g/min (p < 0.01), resulting in a mean absolute quantification error of 23% when a labeling efficiency appropriate for controls was assumed. This difference cannot be accounted for by BAT (whole-brain BAT: control, 1.13 ± 0.06 s; SCA, 1.02 ± 0.09 s) or tissue T1variation. In conclusion, BAT variation influences pCASL quantification less than elevated cervical arterial velocity and labeling efficiency variation in SCA adults; thus, a lower labeling efficiency (α = 0.72) or subject-specific labeling efficiency should be incorporated for SCA patients.
authors.affiliation: Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: Meher R
authors.initials: MR
authors.lastname: Juttukonda
authors.affiliation: Department of Pediatrics, Division of Pediatric Neurology, Vanderbilt Medical Center, Nashville, Tennessee, USA.
authors.forename: Lori C
authors.initials: LC
authors.lastname: Jordan
authors.affiliation: Department of Pediatrics, Division of Pediatric Neurology, Vanderbilt Medical Center, Nashville, Tennessee, USA.
authors.forename: Melissa C
authors.initials: MC
authors.lastname: Gindville
authors.affiliation: Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: Larry T
authors.initials: LT
authors.lastname: Davis
authors.affiliation: Medical Scientist Training Program, Vanderbilt University, Nashville, Tennessee, USA.
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Watchmaker
authors.affiliation: Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: Sumit
authors.initials: S
authors.lastname: Pruthi
authors.affiliation: Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee, USA.|Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.|Department of Psychiatry, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
authors.forename: Manus J
authors.initials: MJ
authors.lastname: Donahue
mesh_terms: D000328:Adult; D000755:Anemia, Sickle Cell / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D001783:Blood Flow Velocity; D002533:Cerebral Angiography / Q000379:methods*; D002560:Cerebrovascular Circulation; D003287:Contrast Media; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels
chemical_list: D003287:Contrast Media; D013113:Spin Labels
keywords: MR angiography (MRA); neurovascular diseases; perfusion spin labeling methods; quantitation