Different methods, different results? Threshold-based versus conventional contouring techniques in clinical practice

BACKGROUND: The quantitative differences of left and right ventricular (LV, RV) parameters of using different cardiac MRI (CMR) post-processing techniques and their clinical impact are less studied. We aimed to assess the differences and their clinical impact between the conventional contouring (CC) and the threshold-based (TB) methods using 70% and 50% thresholds in different hypertrabeculated conditions. METHODS: This retrospective study included 30 dilated cardiomyopathy, 30 left ventricular non-compaction (LVNC), 30 arrhythmogenic cardiomyopathy patients, 30 healthy athletes and 30 healthy volunteers. All participants underwent CMR imaging on 1.5 T. Cine sequences were used to derive measures of the cardiac volumes, function, total muscle mass (TMi) and trabeculae and papillary muscle mass (TPMi) using CC and TB segmentation methods. RESULTS: Comparing the CC and the 70% and 50% threshold TB methods, the LV and RV volumes were significantly lower, the ejection fraction (EF) and the TMi were significantly higher with the TB methods. Between the two threshold setups, only TPMi was significantly higher with the 70% threshold. Regarding the clinical benefits, the LVNC was the only group in whom all the diagnostic and therapeutic decisions and risk stratification were influenced using the TB method. Diagnostic changes occurred in three-quarters of the population, and all the cardiomyopathy groups were affected regarding the decision-making about pharmaco- and device therapy. CONCLUSIONS: Using the TB method, only TPMi was significantly higher with the 70% threshold than the 50% setup, and both of them differed significantly from the CC technique, with relevant clinical impacts in all patient groups.