Cortical cerebral blood flow in ageing: effects of haematocrit, sex, ethnicity and diabetes

Lorna A. Smith, Andrew Melbourne, David Owen, M. Jorge Cardoso, Carole H. Sudre, Therese Tillin, Magdalena Sokolska, David Atkinson, Nish Chaturvedi, Sebastien Ourselin, Alun D. Hughes, Frederik Barkhof, H. R. Jäger

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Objectives: Cerebral blood flow (CBF) estimates from arterial spin labelling (ASL) show unexplained variability in older populations. We studied the impact of variation of haematocrit (Hct) on CBF estimates in a tri-ethnic elderly population. Materials and methods: Approval for the study was obtained from the Fulham Research Ethics Committee and participants gave written informed consent. Pseudo-continuous arterial spin labelling was performed on 493 subjects (age 55–90) from a tri-ethnic community-based cohort recruited in London. CBF was estimated using a simplified Buxton equation, with and without correction for Hct measured from blood samples. Differences in perfusion were compared, stratified by sex, ethnicity and diabetes. Results of Student’s t tests were reported with effect size. Results: Hct adjustment decreased CBF estimates in all categories except white European men. The decrease for women was 2.7 (3.0, 2.4) mL/100 g/min) (mean (95% confidence interval (CI)), p < 0.001 d = 0.38. The effect size differed by ethnicity with estimated mean perfusion in South Asian and African Caribbean women found to be lower by 3.0 (3.6, 2.5) mL/100 g/min, p < 0.001 d = 0.56 and 3.1 (3.6, 2.5) mL/100 g/min), p < 0.001 d = 0.48, respectively. Estimates of perfusion in subjects with diabetes decreased by 1.8 (2.3, 1.4) mL/100 g/min, p < 0.001 d = 0.23) following Hct correction. Correction for individual Hct altered sample frequency distributions of CBF values, especially in women of non-European ethnicity. Conclusion: ASL-derived CBF values in women, non-European ethnicities and individuals with diabetes are overestimated if calculations are not appropriately adjusted for individual Hct. Key Points: • CBF quantification from ASL using a fixed Hct of 43.5%, as recommended in the ISMRM white paper, may lead to erroneous CBF estimations particularly in non-European and female subjects. • Individually measured Hct values improve the accuracy of CBF estimation and, if these are not available, an adjusted value according to gender, ethnicity or diabetes status should be considered. • Hct-corrected ASL could be potentially important for CBF threshold decision making in the fields of neurodegenerative disease and neuro-oncology.
Original languageEnglish
JournalEuropean Radiology
Early online date18 Mar 2019
DOIs
Publication statusPublished - 2019

Cite this

Smith, Lorna A. ; Melbourne, Andrew ; Owen, David ; Cardoso, M. Jorge ; Sudre, Carole H. ; Tillin, Therese ; Sokolska, Magdalena ; Atkinson, David ; Chaturvedi, Nish ; Ourselin, Sebastien ; Hughes, Alun D. ; Barkhof, Frederik ; Jäger, H. R. / Cortical cerebral blood flow in ageing : effects of haematocrit, sex, ethnicity and diabetes. In: European Radiology. 2019.
@article{3ef01d31d1764f48b8208c5f6a963e3e,
title = "Cortical cerebral blood flow in ageing: effects of haematocrit, sex, ethnicity and diabetes",
abstract = "Objectives: Cerebral blood flow (CBF) estimates from arterial spin labelling (ASL) show unexplained variability in older populations. We studied the impact of variation of haematocrit (Hct) on CBF estimates in a tri-ethnic elderly population. Materials and methods: Approval for the study was obtained from the Fulham Research Ethics Committee and participants gave written informed consent. Pseudo-continuous arterial spin labelling was performed on 493 subjects (age 55–90) from a tri-ethnic community-based cohort recruited in London. CBF was estimated using a simplified Buxton equation, with and without correction for Hct measured from blood samples. Differences in perfusion were compared, stratified by sex, ethnicity and diabetes. Results of Student’s t tests were reported with effect size. Results: Hct adjustment decreased CBF estimates in all categories except white European men. The decrease for women was 2.7 (3.0, 2.4) mL/100 g/min) (mean (95{\%} confidence interval (CI)), p < 0.001 d = 0.38. The effect size differed by ethnicity with estimated mean perfusion in South Asian and African Caribbean women found to be lower by 3.0 (3.6, 2.5) mL/100 g/min, p < 0.001 d = 0.56 and 3.1 (3.6, 2.5) mL/100 g/min), p < 0.001 d = 0.48, respectively. Estimates of perfusion in subjects with diabetes decreased by 1.8 (2.3, 1.4) mL/100 g/min, p < 0.001 d = 0.23) following Hct correction. Correction for individual Hct altered sample frequency distributions of CBF values, especially in women of non-European ethnicity. Conclusion: ASL-derived CBF values in women, non-European ethnicities and individuals with diabetes are overestimated if calculations are not appropriately adjusted for individual Hct. Key Points: • CBF quantification from ASL using a fixed Hct of 43.5{\%}, as recommended in the ISMRM white paper, may lead to erroneous CBF estimations particularly in non-European and female subjects. • Individually measured Hct values improve the accuracy of CBF estimation and, if these are not available, an adjusted value according to gender, ethnicity or diabetes status should be considered. • Hct-corrected ASL could be potentially important for CBF threshold decision making in the fields of neurodegenerative disease and neuro-oncology.",
author = "Smith, {Lorna A.} and Andrew Melbourne and David Owen and Cardoso, {M. Jorge} and Sudre, {Carole H.} and Therese Tillin and Magdalena Sokolska and David Atkinson and Nish Chaturvedi and Sebastien Ourselin and Hughes, {Alun D.} and Frederik Barkhof and J{\"a}ger, {H. R.}",
year = "2019",
doi = "10.1007/s00330-019-06096-w",
language = "English",
journal = "European Radiology",
issn = "0938-7994",
publisher = "Springer Verlag",

}

Smith, LA, Melbourne, A, Owen, D, Cardoso, MJ, Sudre, CH, Tillin, T, Sokolska, M, Atkinson, D, Chaturvedi, N, Ourselin, S, Hughes, AD, Barkhof, F & Jäger, HR 2019, 'Cortical cerebral blood flow in ageing: effects of haematocrit, sex, ethnicity and diabetes' European Radiology. https://doi.org/10.1007/s00330-019-06096-w, https://doi.org/10.1007/s00330-019-06096-w

Cortical cerebral blood flow in ageing : effects of haematocrit, sex, ethnicity and diabetes. / Smith, Lorna A.; Melbourne, Andrew; Owen, David; Cardoso, M. Jorge; Sudre, Carole H.; Tillin, Therese; Sokolska, Magdalena; Atkinson, David; Chaturvedi, Nish; Ourselin, Sebastien; Hughes, Alun D.; Barkhof, Frederik; Jäger, H. R.

In: European Radiology, 2019.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Cortical cerebral blood flow in ageing

T2 - effects of haematocrit, sex, ethnicity and diabetes

AU - Smith, Lorna A.

AU - Melbourne, Andrew

AU - Owen, David

AU - Cardoso, M. Jorge

AU - Sudre, Carole H.

AU - Tillin, Therese

AU - Sokolska, Magdalena

AU - Atkinson, David

AU - Chaturvedi, Nish

AU - Ourselin, Sebastien

AU - Hughes, Alun D.

AU - Barkhof, Frederik

AU - Jäger, H. R.

PY - 2019

Y1 - 2019

N2 - Objectives: Cerebral blood flow (CBF) estimates from arterial spin labelling (ASL) show unexplained variability in older populations. We studied the impact of variation of haematocrit (Hct) on CBF estimates in a tri-ethnic elderly population. Materials and methods: Approval for the study was obtained from the Fulham Research Ethics Committee and participants gave written informed consent. Pseudo-continuous arterial spin labelling was performed on 493 subjects (age 55–90) from a tri-ethnic community-based cohort recruited in London. CBF was estimated using a simplified Buxton equation, with and without correction for Hct measured from blood samples. Differences in perfusion were compared, stratified by sex, ethnicity and diabetes. Results of Student’s t tests were reported with effect size. Results: Hct adjustment decreased CBF estimates in all categories except white European men. The decrease for women was 2.7 (3.0, 2.4) mL/100 g/min) (mean (95% confidence interval (CI)), p < 0.001 d = 0.38. The effect size differed by ethnicity with estimated mean perfusion in South Asian and African Caribbean women found to be lower by 3.0 (3.6, 2.5) mL/100 g/min, p < 0.001 d = 0.56 and 3.1 (3.6, 2.5) mL/100 g/min), p < 0.001 d = 0.48, respectively. Estimates of perfusion in subjects with diabetes decreased by 1.8 (2.3, 1.4) mL/100 g/min, p < 0.001 d = 0.23) following Hct correction. Correction for individual Hct altered sample frequency distributions of CBF values, especially in women of non-European ethnicity. Conclusion: ASL-derived CBF values in women, non-European ethnicities and individuals with diabetes are overestimated if calculations are not appropriately adjusted for individual Hct. Key Points: • CBF quantification from ASL using a fixed Hct of 43.5%, as recommended in the ISMRM white paper, may lead to erroneous CBF estimations particularly in non-European and female subjects. • Individually measured Hct values improve the accuracy of CBF estimation and, if these are not available, an adjusted value according to gender, ethnicity or diabetes status should be considered. • Hct-corrected ASL could be potentially important for CBF threshold decision making in the fields of neurodegenerative disease and neuro-oncology.

AB - Objectives: Cerebral blood flow (CBF) estimates from arterial spin labelling (ASL) show unexplained variability in older populations. We studied the impact of variation of haematocrit (Hct) on CBF estimates in a tri-ethnic elderly population. Materials and methods: Approval for the study was obtained from the Fulham Research Ethics Committee and participants gave written informed consent. Pseudo-continuous arterial spin labelling was performed on 493 subjects (age 55–90) from a tri-ethnic community-based cohort recruited in London. CBF was estimated using a simplified Buxton equation, with and without correction for Hct measured from blood samples. Differences in perfusion were compared, stratified by sex, ethnicity and diabetes. Results of Student’s t tests were reported with effect size. Results: Hct adjustment decreased CBF estimates in all categories except white European men. The decrease for women was 2.7 (3.0, 2.4) mL/100 g/min) (mean (95% confidence interval (CI)), p < 0.001 d = 0.38. The effect size differed by ethnicity with estimated mean perfusion in South Asian and African Caribbean women found to be lower by 3.0 (3.6, 2.5) mL/100 g/min, p < 0.001 d = 0.56 and 3.1 (3.6, 2.5) mL/100 g/min), p < 0.001 d = 0.48, respectively. Estimates of perfusion in subjects with diabetes decreased by 1.8 (2.3, 1.4) mL/100 g/min, p < 0.001 d = 0.23) following Hct correction. Correction for individual Hct altered sample frequency distributions of CBF values, especially in women of non-European ethnicity. Conclusion: ASL-derived CBF values in women, non-European ethnicities and individuals with diabetes are overestimated if calculations are not appropriately adjusted for individual Hct. Key Points: • CBF quantification from ASL using a fixed Hct of 43.5%, as recommended in the ISMRM white paper, may lead to erroneous CBF estimations particularly in non-European and female subjects. • Individually measured Hct values improve the accuracy of CBF estimation and, if these are not available, an adjusted value according to gender, ethnicity or diabetes status should be considered. • Hct-corrected ASL could be potentially important for CBF threshold decision making in the fields of neurodegenerative disease and neuro-oncology.

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UR - https://www.ncbi.nlm.nih.gov/pubmed/30887200

U2 - 10.1007/s00330-019-06096-w

DO - 10.1007/s00330-019-06096-w

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JO - European Radiology

JF - European Radiology

SN - 0938-7994

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