Table 2 MR method and parameters, vascular challenge, stimulus effect and regions of interest
Study | MR method | Vascular challenge | Stimulus effect—CVR values | Stimulus effect—etCO2 values (mmHg) | Brain regions analysed |
|---|---|---|---|---|---|
Calviere et al. [34] | DSC EPI 1.5T TE: 30 ms | 15 mg/kg injection of acetazolamide | Frontal CVR DCS − 13.5 ± 13.2% BOLD/mmHg No DCS 20.2 ± 21.3% BOLD/mmHg Temporoparietal CVR DCS − 7.2 ± 22.2% BOLD/mmHg No DCS 12.7 ± 25.1% BOLD/mmHg | N/A | ROIs: Frontal, temporoparietal |
Cantin et al. [13] | BOLD EPI 1.5T TR: 3000 ms TE: 45 ms voxel size 4 × 4 × 4 mm3 32 axial slices | Carbogen (7% CO2 in 93% O2) Air (1 min) − carbogen (2 min) − air (1 min) × 3, Duration 12 min | MCI 0.36 ± 0.12% BOLD/mmHg AD 0.36 ± 0.13% BOLD/mmHg HC 0.62 ± 0.20% BOLD/mmHg | Baseline MCI 39.9 ± 7.3 AD 34.6 ± 5.6 HC 42.3 ± 5.5 ΔetCO2 MCI 13.8 ± 8.9 AD 12.3 ± 5 HC 8.9 ± 3.3 | ROIs: frontal, parietal, temporal and occipital lobes, cingulum, insula, striatum and thalamus |
Chung et al. [32] | CASL w FAIR 3T Scanning parameters not reported | Vasodilation with CO2 rebreathing, reactivity slope from rebreathing to hyperventilation. CVR values reported are from the vasodilation measure | T2DM Baseline 1.1 ± 0.7 ml/100 g/min 2-year follow up 1.0 ± 1.0 ml/100 g/min HC Baseline 0.69 ± 0.43 ml/100 g/min 2-year follow up 0.39 ± 1.50 ml/100 g/min | Not reported | ROIs: Global, frontal, temporal, parietal, occipital and insula |
Gauthier et al. [33] | pCASL w FAIR 3T simultaneous CBF and BOLD BOLD CVR data reported TR: 3000 ms TE1: 10 ms TE2: 30 ms voxel size 4 × 4 mm2 11 slices of 7 mm (1 mm slice gap) | Computer controlled gas delivery system 2 × 2 min blocks of hypercapnia with 2 min of air before and after each block. | Older adults 0.25 ± 0.08%BOLD/mmHg Younger adults 0.25 ± 0.06% BOLD/mmHg | etCO2 targeted to 40 mmHg at baseline, 45 mmHg during hypercapnia etO2 targeted to 100 mmHg throughout | ROI: frontal lobe |
Glodzik et al. [37] | PASL w FAIR 3T TR: 3400 ms TE: 17 ms TI: 1200 ms voxel size 1.2 × 1.2 × 6 mm3 | CO2 rebreathing | MCI Global cortical 0.31 ± 1.2 ml/100 g/min Averaged hippocampus − 0.05 ± 1.7 ml/100 g/min HC Global cortical ± 1.5 ml/100 g/min Averaged hippocampus 1.4 ± 2.7 ml/100 g/min | Baseline MCI 38.7 ± 5.9 HC 39.2 ± 3.1 ΔetCO2 MCI 6.2 ± 1.4 HC 7.1 ± 1.8 | ROIs: Global cortical, hippocampus |
Metzger et al. [36] | BOLD EPI 3T TR:3000 ms TE: 20 ms voxel size 3 × 3 × 3.2 mm3 44 slices | 8% CO2 enriched-gas (BACTAL®) Air (1 min)–BACTAL® (2 min)–air (2 min)–BACTAL® (2 min)–air (2 min)–BACTAL® (2 min)–air (1 min) | Global median CVR Patients CI 0.151 ± 0.06% BOLD/mmHg Patients CN 0.212 ± 0.06% BOLD/mmHg HC 0.207 ± 0.06% BOLD/mmHg | Not monitored, mean etCO2 obtained from a standard population | Global median grey matter ROIs: frontal, parietal, occipital, temporal, insula, striatum, thalamus, cingulum |
Richiardi et al. [31] | BOLD EPI 3T TR: 2970 ms TEs: 12.3, 29.5, 46.8, and 64 ms voxel size 3.44 × 3.44 × 3.5 mm3 34 axial slices | 7% CO2 in medical air administered via a nasal canula Air (1 min)–CO2 (2 min)–air (2 min)–CO2 (2 min)–air (2 min) Duration 9 min | Not reported | Not monitored | Lobe level (7 lobes) and regional level analysis (88 regions) |
Tchistiakova et al. [10] | BOLD 3T TR: 2000Â ms TE: 30Â ms 32 axial slices | Successive breath holds 6 breath holds lasting 15Â s each following 3Â s expiration period with intermittent 30Â s periods of normal breathing CVR calculated as %change in BOLD signal, not corrected for etCO2 | Not reported | Not monitored | Voxel-wise CVR map Only ROIs that differed between groups specified: left pericalcarine cortex, right inferior parietal, lateral occipital and precuneus, and bilateral cuneus, lingual gyri and superior parietal lobes |
Thomas et al. [35] | BOLD 3T Scanning parameters not reported | 5% CO2 in medical air, administered through a mouthpiece, nose-clip fitted CO2 (1 min)–air (1 min) repeated three times | MCI 0.174 ± 0.04% BOLD/mmHg HC 0.170 ± 0.03% BOLD/mmHg | Not reported | Whole brain grey matter |
Yezhuvath et al. [30] | BOLD EPI 3T TR: 3000 ms TE: 30 ms Voxel size 1.7 × 1.7 mm2 25 axial slices | 5% CO2 in medical air alternating between gas and room air every minute Duration 7 min | Not reported | Baseline AD 33.9 ± 3.5 HC 33.7 ± 5.3 ΔetCO2 AD 11.9 ± 1.9 HC 12.2 ± 1.4 | Voxel-wise map and ROI analysis ROIs: occipital lobe, temporal lobe, frontal lobe, parietal lobe, insular cortex and subcortical grey matter |