The Placental Distal Villous Hypoplasia Pattern: Interobserver Agreement and Automated Fractal Dimension as an Objective Metric.
The distal villous hypoplasia (DVH) pattern is a placental correlate of fetal growth restriction. Because the pattern seems to involve less complexity than do appropriately developed placental villi, we postulated that it may be associated with lower fractal dimension-a mathematical measure of complexity. Our study objectives were to evaluate interobserver agreement related to the DVH pattern among expert pathologists and to determine whether pathologist classification of DVH correlates with fractal dimension. A study set of 30 images of placental parenchyma at ×4 magnification was created by a single pathologist from a digital slide archive. The images were graded for the DVH pattern according to pre-specified definitions and included 10 images graded as "no DVH" (grade  =  0), 10 with mild to moderate DVH (grade  =  1), and 10 with severe DVH (grade  =  2). The images were randomly sorted and shown to a panel of 4 international experts who similarly graded the images for DVH. Weighted kappas were calculated. For each image, fractal dimension was calculated by the Box Counting method. The correlation coefficient between (1) the averaged DVH scores obtained by the 5 pathologists and (2) fractal dimension was calculated. The mean weighted kappa score among the observers was 0.59 (range: 0.42-0.70). The correlation coefficient between fractal dimension and the averaged DVH score was -0.915 (P < 0.001). Expert pathologists achieve fair to substantial agreement in grading DVH, indicating consensus on the definition of DVH. Distal villous hypoplasia correlates extremely well with fractal dimension and represents an objective measure for DVH.
1 Department of Pathology and Laboratory Medicine, Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, ON, Canada.
Anika
A
Mukherjee
2 Department of Systems and Computer Engineering, Carleton University and Ottawa-Carleton Institute for Biomedical Engineering, Ottawa, ON, Canada.
Adrian D C
AD
Chan
3 Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, ON, Canada.
Sarah
S
Keating
4 Department of Pathology, Case Western Reserve University, Cleveland, OH, USA.
Raymond W
RW
Redline
5 Department of Pathology, Northwestern Memorial Hospital, Chicago, IL, USA.
Michael K
MK
Fritsch
6 Professor Emeritus, Pediatric Pathology, University of Alberta, Edmonton, AB, Canada (Retired).
Geoffrey A
GA
Machin
7 Department of General Surgery, University of Toronto, Toronto, ON, Canada.
Daniel
D
Cornejo-Palma
1 Department of Pathology and Laboratory Medicine, Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, ON, Canada.
Joseph
J
de Nanassy
1 Department of Pathology and Laboratory Medicine, Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, ON, Canada.
Dina
D
El-Demellawy
8 Department of Obstetrics & Gynaecology, University of British Columbia and BC Women's Hospital & Health Centre, Vancouver, BC, Canada.
Peter
P
von Dadelszen
9 Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada.
Samantha J
SJ
Benton
1 Department of Pathology and Laboratory Medicine, Children's Hospital of Eastern Ontario and University of Ottawa, Ottawa, ON, Canada.
David
D
Grynspan
D001331:Automation; D001706:Biopsy; D002824:Chorionic Villi / Q000473:pathology*; D005317:Fetal Growth Retardation / Q000473:pathology*; D017709:Fractals; D005865:Gestational Age; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D015588:Observer Variation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012720:Severity of Illness Index
distal villous hypoplasia; fractal; fractal dimension; image analysis; interobserver agreement; placenta