Pharmacokinetic modeling of multislice dynamic contrast-enhanced MRI in normal-healing radial fractures: A pilot study.
OBJECTIVE
To define the range of quantitative pharmacokinetic parameters in normal-healing bone with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). DCE-MRI is an established technique for characterizing abnormal tissue microvasculature within solid tumors, but has also shown promise for assessing bone and bone marrow.


METHODS
In this study ethical approval for eight patients was obtained. Inclusion criteria were an extra-articular distal radial fracture in patients aged 20-50 years which had united by 6 weeks in plaster cast. This was assessed by an experienced orthopedic surgeon. DCE-MRI was performed at 1.5T 6 weeks after initial injury. The transfer constant (K(trans) ), transfer rate (Kep ), and initial area under the curve (IAUC) values for the fracture site and adjacent marrow were obtained for each patient.


RESULTS
The mean T1 , K(trans) , Kep , and IAUC at the fracture site were 1713 (standard deviation [SD] 645), 0.09 (SD 0.07), 0.17 (SD 0.17) and 4.9 (SD 4.4). The relative standard deviation (RSD) for the fracture site ranged from 0.38 to 0.97 and for the adjacent marrow ranged from 0.95-3.88. Within each patient the range of RSDs was 0.04-0.42 for T1 , 0.26-0.91 for K(trans) , 0.14-1.06 for Kep , and 0.35-0.96 for the IAUC.


CONCLUSIONS
Pharmacokinetic measures of perfusion can be obtained from healing fractures using DCE-MRI with "excellent" intraclass correlation coefficients for inter- and intrarater reliability. The use of these perfusion parameters is limited by wide patient-to-patient variation and slice-to-slice variation within patients.
Norfolk and Norwich University Hospitals NHS Trust, Department of Radiology, Norwich, UK.
Mark
M
Lewis
Norfolk and Norwich University Hospitals NHS Trust, Department of Orthopaedics and Trauma, Norwich, UK.
Darren
D
Ebreo
Norfolk and Norwich University Hospitals NHS Trust, Department of Radiology, Norwich, UK.
Paul N
PN
Malcolm
Norfolk and Norwich University Hospitals NHS Trust, Department of Radiology, Norwich, UK.
Richard
R
Greenwood
Norfolk and Norwich University Hospitals NHS Trust, Department of Orthopaedics and Trauma, Norwich, UK.
Amratlal D
AD
Patel
Norfolk and Norwich University Hospitals NHS Trust, Department of Radiology, Norwich, UK.
Bahman
B
Kasmai
University of East Anglia, School of Medicine, Norwich, UK.
Glyn
G
Johnson
Norfolk and Norwich University Hospitals NHS Trust, Department of Radiology, Norwich, UK.
Andoni P
AP
Toms
D000328:Adult; D019540:Area Under Curve; D001853:Bone Marrow / Q000000981:diagnostic imaging / Q000473:pathology; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology; D003287:Contrast Media / Q000493:pharmacokinetics*; D005260:Female; D017102:Fracture Healing; D050723:Fractures, Bone / Q000000981:diagnostic imaging* / Q000473:pathology*; D005682:Gadolinium / Q000737:chemistry; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D008833:Microcirculation; D008875:Middle Aged; D009985:Orthopedics / Q000379:methods; D010477:Perfusion; D015203:Reproducibility of Results; D055815:Young Adult
D003287:Contrast Media; D005682:Gadolinium
DCE_MRI; fracture; radius; reliability