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A realistic phantom for validating MRI ‐based synthetic CT images of the human skull
Author(s) -
Soliman Abraam S.,
Burns Levi,
Owrangi Amir,
Lee Young,
Song William Y.,
Stanisz Greg,
Chugh Brige P.
Publication year - 2017
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1002/mp.12428
Subject(s) - imaging phantom , skull , cortical bone , human skull , biomedical engineering , nuclear medicine , anatomy , computer science , medicine
Purpose To introduce a new realistic human skull phantom for the validation of synthetic CT images of cortical bone from ultra‐short echo‐time ( UTE ) sequences. Methods A human skull of an adult female was utilized as a realistic representation of skull cortical bone. The skull was stabilized in a special acrylic container and was filled with contrast agents that have T 1 and T 2 relaxation times similar to human brain. The phantom was MR scanned at 3T with UTE and T 2 ‐weighted sequences, followed by CT . A clustering approach was developed to extract the cortical bone signal from MR images. T 2 ∗ maps of the skull were calculated. Synthetic CT images of the bone were compared to cortical bone signal extracted from CT images and confounding factors, such as registration errors, were analyzed. Results Dice similarity coefficient ( DSC ) of UTE ‐detected cortical bone was 0.84 and gradually decreased with decreasing number of spokes. DSC did not significantly depend on echo‐time. Registration errors were found to be significant confounding factors, with 25% decrease in DSC for consistent 2 mm error at each axis. Conclusion This work introduced a new realistic human skull phantom, specifically for the evaluation and analysis of synthetic CT images of cortical bone.