Baker, C

Ferreira, VM

Leal Pelado, J

Masi, A

Neubauer, S

Piechnik, SK

Soundarajan, R

Zhang, Q

Masi, Ambra

Zhang, Qiang

Soundarajan, Raj

Gomes Esteves Leal Pelado, Joana

Neubauer, Stefan

Ferreira, Vanessa

Piechnik, Stefan

Oxford University Research Archive

Pitfalls of blinded T1-map image analysis by human operator and impact on measured stress T1 responses  Ambra Masi, Qiang Zhang, Raj Soundarajan, Joana Leal Pelado, Cassandra Baker, Stefan Neubauer, Vanessa M Ferreira, Stefan K Piechnik. Background Stress T1-mapping is a novel technique for ischaemia testing without the need for gadolinium-based contrast agents. We investigate pitfalls of simple blinded T1-map analysis, using inter-method agreement between MOLLI and ShMOLLI T1-maps as an illustrative example of their impact on stress T1 results.  Methods We prospectively scanned 18 patients (61±15 years; 72% male) referred for clinical stress CMR for inducible ischaemia, with varied pathology. All patients underwent CMR at 1.5 Tesla including cine, rest and Regadenoson stress T1-mapping using both ShMOLLI and MOLLI 5(3)3, perfusion and LGE imaging. Rest and stress T1-maps were analysed in the mid-ventricular short-axis view by a single human operator, blinded to other CMR images. T1 reactivity (T1stress - T1rest)/T1rest was analysed using original and eroded (mid-wall myocardium) contours on the segmental basis (n=108 segments).   Results Stress T1 responses were clearly detectable (Table 1). ShMOLLI T1 measurements had a higher T1 reactivity (4%±4%) compared with MOLLI (3%±4%; p<0.01) in these patients, with both methods showing similar intragroup variability. Head-to-head comparison of ShMOLLI versus MOLLI revealed low positive correlation R=0.15. Minimizing the partial volume as one known source of noise in T1, improved inter-method correlation to R=0.27. Inevitably linked reduction in sample volumes increased the SD and slightly reduced the statistical significance of the apparent difference in reactivity between methods (p<0.03). Inspection of cases with major discrepancies, intended to shed light on unexpectedly weak inter-method correlation, revealed pitfalls in blinded T1-map analysis, such as significant variations in the ROI thickness and failures to include subendocardial infarctions at the blood-myocardium interface (Figure 1).   Conclusion T1-map analysis blinded to LGE imaging by a human operator affects the stress T1 results using both ShMOLLI and MOLLI techniques. Clear pitfalls identified include significant variations in the ROI wall thickness and missing subendocardial infarctions. Multi-stage image analysis approaches with robust quality control are required to deliver more reliable stress T1-mapping for clinical applications.  Table 1. Comparison of segmental ShMOLLI and MOLLI rest-stress T1 (mean±SD) using Regadenoson in 18 patients referred for clinical stress CMR for inducible ischaemia.   Whole myocardium ShMOLLI       MOLLI Mid-wall myocardium ShMOLLI       MOLLI  T1 rest (ms) 941 ± 74 982 ± 77 933 ± 75 1014 ± 58  T1 stress (ms) 982 ± 77 1025 ± 55 976 ± 79 1045 ± 61  ΔT1 (%) 4.5 ± 4.0 2.9 ± 4.0 4.7 ±  5.0 3.2 ± 5.0       

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Pitfalls of blinded T1-map image analysis by human operator and impact on measured stress T1 responses: Conference abstract

Pitfalls of blinded T1-map image analysis by human operator and impact on measured stress T1 responses

Pitfalls of blinded T1-map image analysis by human operator and impact on measured stress T1 responses

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