Chressen Catharina Remus MD, Presenter: Nothing to Disclose

Nils Daniel Forkert, Abstract Co-Author: Nothing to Disclose

Jan Sedlacik, Abstract Co-Author: Nothing to Disclose

Gerhard B. Adam MD, Abstract Co-Author: Nothing to Disclose

Petra Arck, Abstract Co-Author: Nothing to Disclose

Fabian Kording, Abstract Co-Author: Nothing to Disclose

DCE MRI is a commonly applied imaging technique for perfusion quantification and is frequently used in experimental setups for perfusion analysis in the mouse placenta. To date, placental perfusion analysis is commonly performed by determining the average perfusion value for the entire placenta without taking the different functional placental compartments into account. The purpose of this work was to develop an automatic differentiation of the two functional placenta zones in a mouse model based on bolus arrival times for a detailed and reproducible perfusion assessment.

Ten pregnant BALB/c mice at gestation day 16.5 were examined at 7T. Coronal dual-echo 3D T1-weighted gradient-echo sequences were acquired after application of contrast agent for dynamic MR-imaging. An adapted gamma variate function was fitted to the concentration time curves to evaluate the effect of noise on perfusion and segmentation results. Maps of the bolus arrival time were calculated based on discrete and fitted curves and used to classify each voxel into a high-flow and low-flow compartment based on k-mean clustering. Segmentation results were evaluated based on the DICE coefficient with manually delineated compartments from two independent observers. Perfusion analysis was performed on discrete and fitted curves using the steepest slope model.

Manually delineated high-flow and low-flow compartments agreed with automatic segmented compartments for discrete (D=0.76/0.75; D=0.76/0.79) and fitted (D=0.80/0.80; D=0.81/0.82) concentration time curves. Mean perfusion values of discrete and fitted curves ranged in the high flow compartment from 134 to 142 ml/min/100ml (discrete) vs. 138 to 143 ml/min/100ml (fitted) and in the low-flow compartment from 91 to 94 ml/min/100ml (discrete) vs. 74 to 82 ml/min/100ml (fitted).

Functional perfusion compartments can be automatically differentiated using bolus arrival times with a high agreement to manual differentiations. Fitting of the gamma variate function improves segmentation results.The proposed method may overcome reported limitations in perfusion analyses by eliminating the subjective choice of regions of interest.

The heterogeneity within the placenta with its two functional compartments generates the need for separate compartment analysis to enable a more detailed and reproducible understanding of placenta perfusion.

Remus, C, Forkert, N, Sedlacik, J, Adam, G, Arck, P, Kording, F, Automatic Differentiation of Functional Placental Compartments for Perfusion Analysis in the Mouse Using the Time-to-peak Model at 7T.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14012892.html