General Session: Diagnostic Imaging
Presented by: K. Siemionow
P. Glowka(1,2), K. Siemionow(3), L. Glowka(4), T. Kotwicki(1)
(1) University of Medical Sciences, Department of Spinal Disorders and Pediatric Orthopaedics, Poznan, Poland
(2) University of Illinois at Chicago, Chicago, IL, United States
(3) University of Illinois at Chicago, Department of Orthopaedics, Chicago, IL, United States
(4) University of Medical Sciences, Poznan, Poland
Background: Knowledge of vertebral pedicle dimensions is crucial for safe transpedicular screw placement in scoliosis surgery.To successfully plan the screw's trajectory it is important to estimate: pedicles transverse width, sagittal width, length and pedicle angle (both transverse and sagittal).The aim of this study was to compare pedicle measurements on MRI to those obtained fromCT images in the same subject.
Methods: 34 pedicles of patients with scoliosis (main curve: 60; age:16 years old ) were analyzed on both CT and MRI T2-weighted 3D SPACE sequence images. The transverse pedicle outer width (TPOW), transverse pedicle inner width (TPIW), chord (screw-pathway) length (ChL), transverse pedicle angel (TPA), sagittal pedicle outer width (SPOW), sagittal pedicle inner width (SPIW) and sagittal pedicle angle (SPA) were measured.
Results: There were no statistical difference between measurements performed on MRI and CT for following parameters: TPIW, TPA, ChL, SPOW, SPIW, SPA. The measurements of TPOW reveled asignificant difference (p=0,004) for TPOW measured on MRI vs CT. Outer pedicle width (both transverse and sagittal) was overestimated on CT images in comparison to MRI. Transverse and sagittal inner pedicle width measurments demonstrated no statistical difference on MRI and CT (p=0.365 and 0.347, respectively).
Conclusions: This study demonstrates that MRI of the spine can be successfully used for planning pedicle screw sizes and trajectories. Notwithstanding, it is important to note that MRI has a tendency for susceptibility artifacts potentially altering images of anatomical structures.