COPD Patients Have Short Lung Magnetic Resonance T₁ Relaxation Time

Figures & data

Table 1.  Demographic, pulmonary function, CT density and lung MRI T₁ data

	Healthy	Moderate COPD	Severe COPD
No. of subjects	12	12	12
No. of men	8	9	10
Age (years)	63 ± 12 (42–79)	66 ± 9 (49–80)	65±6 (52–74)
Body mass index (kg/m^2)	25.3 ± 4.1 (18.1–32.1)	28.7 ± 4.3 (23.3–38.6)	25.6 ± 3.4 (20.6–32.9)
Smoking index (pack-years)	0.3 ± 1 (0–3.6)	52 ± 26 (17–102)	47 ± 19 (12–91)
Pulmonary function measurement
FEV1 (% predicted)	121 ± 14 (104–147)	69 ± 9 (51–82)	41 ± 6 (26–49)
FEV1/FVC (% predicted)	78 ± 4 (72–85)	51 ± 8 (40–64)	33 ± 5 (25–44)
DLCO/VA (% predicted)	88 ± 11 (71–109)	69 ± 12 (51–90)	48 ± 15 (26–77)
CT density scan
PD15 (g/L)	ND	58 ± 23 (29–89)	30 ± 22 (2–77)
RA950 (%)	ND	14 ± 9 (4–30)	30 ± 15 (6–55)
Lung MRI measurement
T1 (ms)	1053 ± 55 (953–1167)	947 ± 56 (882–1029)†	911 ± 64 (811–991)†
IQR of T1 (ms)	207 ± 45 (155–291)	324 ± 80 (231–460)†	291 ± 62 (182–385)†

Note: Data are means ± standard deviations, with ranges in parentheses. ND = no data.

†Significant difference with healthy group, p < 0.001.

Figure 1.  Representative coronal lung MRI T₁ maps overlaid on a signal intensity image with corresponding normalised T₁ histograms for healthy, moderate COPD and severe COPD subjects. Both T₁ maps and histograms reflected the severity of COPD by reduced T₁ and increased heterogeneity.

Figure 2.  Global lung T₁ (a) and regional IQR of T₁ (b) for healthy (), moderate COPD (▲) and severe COPD () subjects. T₁ was significantly shorter for the moderate COPD (p < 0.0001) and severe COPD subjects (p < 0.0001) than in the healthy controls. IQR of T₁ was significantly larger for the moderate COPD (p < 0.0001) and severe COPD subjects (p = 0.0002) than in the healthy controls. No statistically significant differences in T₁ and IQR of T₁ were found between the COPD subjects. The error bars indicate standard deviation of the mean.

Figure 3.  Lung T₁ as a function of CT density measurements RA₉₅₀ (a) and PD₁₅ (b), for moderate COPD (▲) and severe COPD () subjects. Significant correlations between lung T₁ and RA₉₅₀ (r = −0.63, p = 0.001) and PD₁₅ (r = 0.50, p = 0.017) were found.

Figure 4.  Lung T₁ as a function of PFT parameters FEV₁ (a), FEV₁/ FVC (b) and DL_CO/VA (c), for healthy (), moderate COPD (▲) and severe COPD () subjects. Strong significant correlations (p < 0.0001) between lung T₁ and all PFT parameters; FEV₁ (r = 0.74), FEV₁/FVC (r = 0.77) and DL_CO/VA (r = 0.75) were observed.