Cardiac T1 and T2 Mapping at 1.5T: Nomograms and Evaluation of Deep Learning Reconstruction

Statistical analysis

Age- and gender-specific upper and lower ranges within each slice were calculated as the mean plus and minus 2 standard deviations of the normal data, respectively. Differences by age, gender, and slice were assessed by three-way repeated measures ANOVA. Repeatability and reproducibility were assessed by the intra-class correlation coefficient (ICC) (Fleiss 1971), repeatability/reproducibiliy coefficient, and Bland-Altman analysis. P-values < 0.05 were considered statistically significant. All analyses were performed in R version 4.3.2 (R Foundation for Statistical Computing, Vienna, Austria).

Subject characteristics

Table 1: Patient age distribution by gender.

		Female (N=28)	Male (N=22)
Age (years)	median (IQR)	44.5 (31, 62.25)	41 (32.5, 53)
	20-29	5 (17.9%)	5 (22.7%)
	30-39	5 (17.9%)	5 (22.7%)
	40-49	5 (17.9%)	6 (27.3%)
	50-59	5 (17.9%)	2 (9.1%)
	60-69	8 (28.6%)	4 (18.2%)

Age- and gender-specific reference ranges

• Slice 1: AHA1 – AHA6, Sept1
• Slice 2: AHA7 – AHA12, Sept2
• Slice 3: AHA13 – AHA16, Sept3

T1 measurements

The age- and gender-specific mean values and 95% ranges are summarized within each slice for MOLLI and SMART in Table 2 and Table 3, and plotted in Figure 1 and Figure 2, respectively. Males tend to have smaller values than females. For MOLLI, slice 3 > slices 1 or 2 in general. Age differences are less clear.

Table 2: Age- and gender-specific mean (95% range) for T1-MOLLI.

Age	Gender	Slice 1	Slice 2	Slice 3
20-29	Female	1029 (935, 1123)	1042 (988, 1096)	1082 (990, 1173)
20-29	Male	954 (902, 1007)	968 (920, 1015)	996 (926, 1066)
30-39	Female	1007 (908, 1106)	1015 (908, 1122)	1050 (926, 1173)
30-39	Male	983 (916, 1051)	978 (895, 1061)	1005 (917, 1093)
40-49	Female	1069 (998, 1140)	1053 (963, 1142)	1106 (1029, 1183)
40-49	Male	968 (875, 1062)	975 (910, 1040)	1001 (920, 1082)
50-59	Female	1011 (905, 1117)	1028 (939, 1116)	1063 (951, 1175)
50-59	Male	994 (919, 1070)	992 (906, 1078)	1024 (881, 1167)
60-69	Female	1031 (903, 1160)	1023 (937, 1108)	1075 (900, 1251)
60-69	Male	974 (906, 1042)	963 (844, 1083)	1013 (855, 1171)

Figure 1: Bar chart for age- and gender-specific mean (95% range) for T1-MOLLI.

Table 3: Age- and gender-specific mean (95% range) for T1-SMART.

Age	Gender	Slice 1	Slice 2	Slice 3
20-29	Female	1260 (1132, 1389)	1263 (1174, 1352)	1328 (1132, 1524)
20-29	Male	1204 (1133, 1276)	1213 (1126, 1301)	1243 (1109, 1376)
30-39	Female	1233 (1139, 1327)	1229 (1111, 1346)	1249 (1105, 1392)
30-39	Male	1211 (1149, 1274)	1215 (1138, 1292)	1218 (1083, 1354)
40-49	Female	1280 (1182, 1379)	1275 (1149, 1401)	1261 (1139, 1384)
40-49	Male	1209 (1113, 1304)	1207 (1124, 1290)	1215 (1067, 1363)
50-59	Female	1255 (1119, 1392)	1253 (1147, 1358)	1254 (1060, 1447)
50-59	Male	1239 (1146, 1332)	1241 (1131, 1350)	1231 (1051, 1410)
60-69	Female	1253 (1129, 1376)	1266 (1174, 1358)	1271 (1070, 1471)
60-69	Male	1228 (1118, 1339)	1221 (1085, 1358)	1228 (1101, 1356)

Figure 2: Bar chart for age- and gender-specific mean (95% range) for T1-SMART.

Three-way ANOVA test (Table 4) confirms that gender and slice differences are significant, and that age difference is not.

Table 4: P-values from three-way ANOVA test on age, gender, and slice differences.

	Age	Gender	Slice
MOLLI	0.864	<0.001	<0.001
SMART	0.407	<0.001	<0.001

T2 measurements

The age- and gender-specific mean values and 95% ranges are summarized within each slice for T2 and T2-fast in Table 5 and Table 6, and plotted in Figure 3 and Figure 4, respectively.

Table 5: Age- and gender-specific mean (95% range) for T2.

Age	Gender	Slice 1	Slice 2	Slice 3
20-29	Female	50.9 (38.8, 63)	52.7 (46.4, 59.1)	55.9 (47.1, 64.6)
20-29	Male	48.6 (42.1, 55.2)	49.6 (43.8, 55.5)	51.8 (41.5, 62.2)
30-39	Female	50.6 (44.1, 57.1)	50.5 (43.6, 57.4)	53.6 (44, 63.1)
30-39	Male	49.8 (44.2, 55.4)	51 (47.2, 54.8)	52.3 (46.2, 58.4)
40-49	Female	50.2 (44, 56.5)	51.3 (44.7, 57.8)	52.6 (46.5, 58.8)
40-49	Male	49.9 (44.6, 55.3)	51.3 (46.1, 56.5)	53.2 (45, 61.4)
50-59	Female	48.9 (40.8, 57)	49.8 (43.6, 56)	51.6 (42.3, 60.8)
50-59	Male	50.3 (44.1, 56.4)	50.1 (47.8, 52.4)	49 (45.2, 52.9)
60-69	Female	53.6 (46.1, 61.1)	54 (46.9, 61.1)	59.8 (44.8, 74.8)
60-69	Male	50.2 (42.6, 57.7)	52.3 (43.9, 60.7)	56.4 (44.7, 68.1)

Figure 3: Bar chart for age- and gender-specific mean (95% range) for T2.

Table 6: Age- and gender-specific mean (95% range) for T2-fast.

Age	Gender	Slice 1	Slice 2	Slice 3
20-29	Female	52.7 (41.2, 64.1)	54.2 (46.8, 61.5)	57.6 (50.2, 65.1)
20-29	Male	48.9 (37.7, 60.1)	50.8 (42.9, 58.7)	51.4 (41.5, 61.3)
30-39	Female	51.9 (44.5, 59.3)	51.5 (40.9, 62)	55 (44.6, 65.4)
30-39	Male	52.1 (44.3, 59.9)	52.7 (46.9, 58.4)	53.2 (46.2, 60.3)
40-49	Female	55.6 (47.1, 64.1)	53.6 (43.7, 63.5)	57 (41.9, 72.2)
40-49	Male	52.3 (45.3, 59.2)	52.7 (46.4, 58.9)	53.9 (45.6, 62.2)
50-59	Female	51.3 (38.7, 63.8)	51.1 (41.5, 60.7)	54.2 (40.5, 67.9)
50-59	Male	52.1 (45.7, 58.5)	52.3 (46.6, 58)	52.3 (44.7, 59.9)
60-69	Female	54.5 (46.2, 62.8)	56.3 (47, 65.7)	62.4 (46.3, 78.5)
60-69	Male	50.9 (43, 58.8)	53.7 (43.2, 64.2)	57 (42.5, 71.5)

Figure 4: Bar chart for age- and gender-specific mean (95% range) for T2-fast.

Three-way ANOVA test (Table 4) shows that age, gender and slice all have significant effects.

Table 7: P-values from three-way ANOVA test on age, gender, and slice differences.

	Age	Gender	Slice
T2	<0.001	0.019	<0.001
T2-fast	0.016	0.007	<0.001

Area of septal contours

The mean and standard deviation (SD) of septal contour area by age and gender for T1 and T2 are summarized in Table 8 and Table 9, respectively. In general, sept1 > sept2 > sept3.

Table 8: Mean (SD) of septal contour area for T1.

Age	Map	Sept	Female	Male
20-29	MOLLI	sept_1_area	244.1 (97.2)	384.4 (96.7)
20-29	MOLLI	sept_2_area	225.1 (66.4)	244.6 (45)
20-29	MOLLI	sept_3_area	103.3 (44.1)	145.4 (45.4)
20-29	SMART	sept_1_area	226.2 (67.3)	357 (100)
20-29	SMART	sept_2_area	221.6 (66.8)	242.1 (82)
20-29	SMART	sept_3_area	81.4 (40.6)	133.8 (52.9)
30-39	MOLLI	sept_1_area	229.1 (44.3)	296.3 (73.2)
30-39	MOLLI	sept_2_area	181.7 (44.1)	217.8 (70.7)
30-39	MOLLI	sept_3_area	85.1 (37.6)	110.3 (38.3)
30-39	SMART	sept_1_area	205.7 (50.9)	308.8 (58.2)
30-39	SMART	sept_2_area	172.5 (48.6)	237.6 (60.8)
30-39	SMART	sept_3_area	87.6 (34.2)	112.6 (39.9)
40-49	MOLLI	sept_1_area	276.3 (113)	330.5 (92.1)
40-49	MOLLI	sept_2_area	259.7 (71.1)	250.3 (77.1)
40-49	MOLLI	sept_3_area	120.2 (38.3)	134.3 (49.6)
40-49	SMART	sept_1_area	316.7 (121.4)	307.8 (123.7)
40-49	SMART	sept_2_area	289.6 (88)	256.3 (92.3)
40-49	SMART	sept_3_area	124.8 (51.5)	117.7 (50.1)
50-59	MOLLI	sept_1_area	225.7 (67)	447.9 (145.7)
50-59	MOLLI	sept_2_area	167.1 (27.5)	307.7 (153.5)
50-59	MOLLI	sept_3_area	92.6 (27.3)	144.5 (20.6)
50-59	SMART	sept_1_area	223.1 (66.6)	429.9 (171.1)
50-59	SMART	sept_2_area	166.4 (24.3)	323.4 (115.6)
50-59	SMART	sept_3_area	90.5 (22.9)	120.4 (27.4)
60-69	MOLLI	sept_1_area	212.9 (71)	288.4 (69.7)
60-69	MOLLI	sept_2_area	179.5 (61.3)	195.1 (29.2)
60-69	MOLLI	sept_3_area	76.6 (16.2)	87.5 (38.4)
60-69	SMART	sept_1_area	210.1 (57.4)	225.7 (144.6)
60-69	SMART	sept_2_area	160.8 (57.1)	216.3 (42.2)
60-69	SMART	sept_3_area	65.1 (22.9)	96.7 (33.9)

Table 9: Mean (SD) of septal contour area for T2.

Age	Map	Sept	Female	Male
20-29	T2	sept_1_area	256.3 (117.2)	340.4 (116)
20-29	T2	sept_2_area	239 (45.9)	256.9 (77.4)
20-29	T2	sept_3_area	113.1 (29.1)	141.1 (40.7)
20-29	T2fast	sept_1_area	266.1 (121.1)	449.6 (44.4)
20-29	T2fast	sept_2_area	256.2 (49.3)	265.9 (78.1)
20-29	T2fast	sept_3_area	134.5 (31.2)	153.4 (44.3)
30-39	T2	sept_1_area	284.1 (69.2)	384.6 (135)
30-39	T2	sept_2_area	241.7 (119.4)	258.7 (30.7)
30-39	T2	sept_3_area	123.5 (58.3)	143.6 (36.5)
30-39	T2fast	sept_1_area	185.4 (27.7)	343.1 (129.8)
30-39	T2fast	sept_2_area	235 (104.1)	283.4 (84.7)
30-39	T2fast	sept_3_area	134.6 (65.2)	120.3 (38.2)
40-49	T2	sept_1_area	408.8 (143.5)	411.4 (120.6)
40-49	T2	sept_2_area	312.5 (83.7)	285.1 (61.1)
40-49	T2	sept_3_area	159.6 (58.7)	125.2 (46.4)
40-49	T2fast	sept_1_area	382.9 (168.9)	386.1 (116.7)
40-49	T2fast	sept_2_area	305.3 (80.9)	289.5 (69.7)
40-49	T2fast	sept_3_area	136.7 (39.8)	124.7 (41.1)
50-59	T2	sept_1_area	307.6 (172.2)	378.1 (0.1)
50-59	T2	sept_2_area	208 (50.1)	285.6 (64.7)
50-59	T2	sept_3_area	117 (39.2)	189.2 (69.4)
50-59	T2fast	sept_1_area	314.7 (157.1)	380.7 (171.4)
50-59	T2fast	sept_2_area	191.8 (58.3)	219.3 (65.1)
50-59	T2fast	sept_3_area	112.2 (28.3)	176.4 (78.4)
60-69	T2	sept_1_area	246.4 (94.6)	399.2 (136.7)
60-69	T2	sept_2_area	173.9 (41.7)	212.2 (86.9)
60-69	T2	sept_3_area	86.8 (35.2)	96.2 (37.4)
60-69	T2fast	sept_1_area	214.7 (92.4)	364.5 (159.4)
60-69	T2fast	sept_2_area	175 (76)	219.4 (105)
60-69	T2fast	sept_3_area	84.9 (31.6)	93 (15.8)

Repeatability and Reproducibility

Repeatability for DL reconstructions

The bias, repeatability coefficient (RC), intraclass correlation coefficient (ICC) and 95% confidence interval comparing scan A vs B are tabulated in Table 10. Bland-Altman plots are shown in Figure 5.

Table 10: Repeatability analysis of T1 and T2.

map	Bias	RC	ICC (95% CI)	P-value
MOLLI	19.8	78.3	0.616 (0.527, 0.692)	p<0.001
SMART	7.5	114.7	0.516 (0.405, 0.612)	p<0.001
T2	0.9	6.5	0.59 (0.494, 0.672)	p<0.001
T2fast	0.3	10.7	0.304 (0.175, 0.423)	p<0.001

Figure 5: Bland-Altman analysis of repeatability for T1 and T2

Between-system reproducibility

The bias, reproducibility coefficient (RC), intraclass correlation coefficient (ICC) and 95% confidence interval comparing scan A vs B are tabulated in Table 11. Bland-Altman plots are shown in Figure 6.

Table 11: Between-system reproducibility analysis of T1 and T2.

map	Bias	RC	ICC (95% CI)	P-value
MOLLI	4.4	113.3	0.601 (0.515, 0.675)	p<0.001
SMART	-4.3	148.7	0.45 (0.344, 0.545)	p<0.001
T2	-0.4	10.4	0.41 (0.307, 0.503)	p<0.001
T2fast	-0.5	12.4	0.395 (0.285, 0.495)	p<0.001

Figure 6: Bland-Altman analysis of between-system reproducibility for T1 and T2

Between-sequence reproducibility

The bias, reproducibility coefficient (RC), intraclass correlation coefficient (ICC) and 95% confidence interval comparing MOLLI vs SMART and T2 vs T2fast are tabulated in Table 12. Bland-Altman plots are shown in Figure 7. (Non-inter-system: priority scan A \(\to\) B; inter-system: priority scan B \(\to\) A.) Bias for MOLLI vs SMART is substantial: SMART values are bigger, causing lack of agreement.

Table 12: Between-sequence reproducibility analysis of T1 and T2.

	Bias	RC	ICC (95% CI)	P-value
MOLLI vs SMART	-228.6	142.9	-0.641 (-0.679, -0.601)	p=1
T2 vs T2-fast	-1.5	9.5	0.598 (0.554, 0.64)	p<0.001

Figure 7: Bland-Altman analysis of between-sequence reproducibility for T1 and T2

Between-recon reproducibility

The bias, reproducibility coefficient (RC), intraclass correlation coefficient (ICC) and 95% confidence interval comparing MOLLI: Std vs DL, T2: Std vs DL, and T2: DL vs GE are tabulated in Table 13. Bland-Altman plots are shown in Figure 8. (Non-inter-system: priority scan A \(\to\) B; inter-system: priority scan B \(\to\) A.) There is strong agreement within the three pairs of comparisons.

Table 13: Between-recon reproducibility analysis of T1 and T2.

	Bias	RC	ICC (95% CI)	P-value
MOLLI: Std vs DL	-0.7	41.5	0.944 (0.936, 0.95)	p<0.001
T2: Std vs DL	0.1	3.1	0.951 (0.944, 0.956)	p<0.001
T2: DL vs GE	-0.6	3.8	0.906 (0.893, 0.918)	p<0.001

Figure 8: Bland-Altman analysis of between-recon reproducibility for T1 and T2

Between-reader reproducibility

The bias, reproducibility coefficient (RC), intraclass correlation coefficient (ICC) and 95% confidence interval comparing RVS vs AF for MOLLI and T2 are tabulated in Table 14. Bland-Altman plots are shown in Figure 9. (Non-inter-system: priority scan A \(\to\) B; inter-system: priority scan B \(\to\) A.) The inter-reader agreement is strong.

Table 14: Between-reader (RVS vs AF) reproducibility analysis of MOLLI and T2.

	Bias	RC	ICC (95% CI)	P-value
MOLLI	1.6	70.2	0.807 (0.765, 0.842)	p<0.001
T2	0.8	6.4	0.711 (0.654, 0.76)	p<0.001

Figure 9: Bland-Altman analysis of between-reader (RVS vs AF) reproducibility for MOLLI and T2

References

Fleiss, Joseph L. 1971. “Measuring Nominal Scale Agreement Among Many Raters.” Psychological Bulletin 76 (5): 378–82. https://doi.org/10.1037/h0031619.