Mantel-Haenzel row mean score test statistic (P value) based on a χ2 distribution with 1 degree of freedom (3 degrees of freedom for the overall analysis), stratified on matched pairs, for every vessel and image quality parameter by reader
| Vessel | Reader 1 | Reader 2 | Reader 3 | Overall |
|---|---|---|---|---|
| Arterial score 1: CCA | 9.3077 (0.0023) | 4.0000 (0.0455) | 2.0000 (0.1573) | 15.3077 (0.0016) |
| Arterial score 2: Bifurcation | 9.0000 (0.0027) | 8.3333 (0.0039) | 5.0000 (0.0253) | 22.3333 (<0.0001) |
| Arterial score 3: ICA | 8.8947 (0.0029) | 8.0000 (0.0047) | 4.0000 (0.0455) | 20.8947 (0.0001) |
| Arterial score 4: ECA | 8.8947 (0.0029) | 9.0000 (0.0027) | 4.0000 (0.0455) | 21.8947 (<0.0001) |
| Arterial score 5: Intraosseous portion of ICA | 9.2807 (0.0023) | 8.8947 (0.0029) | 5.0000 (0.0253) | 23.1754 (<0.0001) |
| Arterial score 6: Vertebral arteries | 6.4000 (0.0114) | 8.3333 (0.0039) | 7.0000 (0.0082) | 21.7333 (<0.0001) |
| Arterial score 7: Basilar artery | 8.9091 (0.0028) | 10.000 (0.0016) | 6.2308 (0.0126) | 25.1399 (<0.0001) |
| Arterial score 8: Communicating arteries | 8.8947 (0.0029) | 8.8947 (0.0029) | 6.2308 (0.0126) | 24.0202 (<0.0001) |
| Arterial score 9: First segments: A1, M1, P1 | 8.3333 (0.0039) | 6.0000 (0.0143) | 9.0000 (0.0027) | 23.3333 (<0.0001) |
| Arterial score 10: Second segments: A2, M2, P2 | 9.0000 (0.0027) | 8.3333 (0.0039) | 9.3077 (0.0023) | 26.3333 (<0.0001) |
| Arterial score 11: Third segments: A3, M3, P3 | 9.3226 (0.0023) | 9.1429 (0.0025) | 10.000 (0.0016) | 28.4655 (<0.0001) |
| Venous score 1: Internal and bridging cerebral veins | 5.4000 (0.0201) | 7.0000 (0.0082) | 4.4545 (0.0348) | 16.8545 (0.0008) |
| Venous score 2: Cavernous sinus | 9.0000 (0.0027) | 4.0000 (0.0455) | 6.0000 (0.0143) | 19.0000 (0.0003) |
| Venous score 3: Superior saggital sinus | 2.0000 (0.1573) | 1.0000 (0.3173) | 0 (1)‡ | 3.0000 (0.3916) |
| Venous score 4: Transverse and sigmoid sinus | 1.0000 (0.3173) | 1.0000 (0.3173) | 1.0000 (0.3173) | 3.0000 (0.3916) |
| Venous score 5: Jugular veins | 1.0000 (0.3173) | 1.0000 (0.3173) | 0 (1)††† | 2.0000 (0.5724) |
| Quality score 1: Quality overall: 1 (poor) to 5 (excellent) | 7.3636 (0.0067) | 9.0000 (0.0027) | 1.0000 (0.3173) | 17.3636 (0.0006) |
| Quality score 2: Artifacts: 1 (cannot be interpreted) to 5 (no artifacts) | 4.0000 (0.0455) | 1.0000 (0.3173) | 0 (1)††† | 5.0000 (0.1718) |
| Quality score 3: Dental artifacts: 1 (cannot be interpreted) to 5 (no artifacts) | 1.0000 (0.3173) | 1.0000 (0.3173) | 0 (1)††† | 2.0000 (0.5724) |
| Quality score 4: Delineation of vascular calcification: 1 (poor) to 5 (excellent) | 9.000 (0.0027)† | 7.118 (0.0076)† | 4.000 (0.0455)† | 20.1176 (0.0002)† |
| Quality score 5: Subjective contrast: 1 (insufficient) to 5 (excellent) | 0 (1)‡ | 6.0000 (0.0143) | 0 (1)‡ | 6.0000 (0.1116) |
Note:—In every instance where the test was significant, the shift in row mean scores was due to a higher distribution of scores for MIP. Significant results are marked in bold. CCA indicates common carotid artery; ICA, internal carotid artery; ECA, external carotid artery.
† In one of the 10 subjects, all readers chose n/a, as no calcifications were discerned with either technique.
‡ Only 2 of the possible 5 scores were used for every subject, for both MIP and MPR. The resulting 2 × 2 table has identical MIP and MPR scores within every subject. Thus, the Mantel-Haenzel row mean score test, stratified on matched pairs, cannot be computed due to a singular covariance matrix. However, in this situation, McNemar’s test for 2 × 2 tables can be used. Here, McNemar’s test statistic is 0 with a P value of 1.
††† MIP and MPR scores are identical within every subject, and thus the Mantel-Haenzel row mean score test, stratified on matched pairs, cannot be computed due to a singular covariance matrix.