Extracellular volume (ECV) is a promising diagnostic and prognostic imaging biomarker in CMR, because it correlates to histological measurements of extracellular space. ECV is measured by native and post-contrast T1-mapping, e.g. based on a modified look locker sequence (MOLLI). For optimal calculation, a prompt and precise measurement of haematocrit is indispensable. In daily routine, blood drawings in hospital are sometimes delayed or not available from the time point when the CMR takes place. Therefore, delayed haematocrit measurement could lead to imprecise ECV values. Haematocrit can...

In a first step, a regression formula using pre and post contrast T1 relaxation times for calculation of the synthetic haematocrit was obtained from a prospective study of 62 healthy volunteers. Therefor, haematocrit measurement took place directly at the time point of MR imaging. Secondly, this regression formula was used to calculate ECV values in a cohort of 40 DCM patients. T1 Maps were post-processed with dedicated cardiovascular software (Circle CVI®, Calgary, Canada). For analysis of ECV, a septal ROI in the midventricular slice was...

ECV calculated from synthetic and true haematocrit values differed significantly from each other (True ECV: 28.8 ± 4.3% vs Synthetic ECV: 29.9 ± 5.1%; p = 0.006), but showed a good correlation between each other (r = 0.88; R2= 0,782) (Figure 2).

ECV calculation using a synthetic haematocrit is a reliable tool to avoid diagnostic uncertainty in case of delayed blood drawings in everyday clinical routine.

Dr. Tilman Emrich Junior-Consultant Radiology University Medical Center Mainz [email protected]