Single photon emission computed tomography (SPECT) and computed tomography (CT) integrated
in one system (SPECT/CT) is an effective co-registration technique that helps to localize
and characterize lesions in the hand and wrist. However, patient motion may cause
misalignment between the two modalities leading to potential misdiagnosis. The aim
of the present study was to evaluate the hardware-based registration accuracy of multislice
SPECT/CT of the hand and wrist and to determine the effect of misalignment errors
on diagnostic accuracy. A total of 55 patients who had multislice SPECT/CT of the
hand and wrist between July 2008 and January 2010 were included. Two reviewers independently
evaluated the fused images for any misalignments with six degrees of freedom: Translation
and rotation in the X, Y and Z directions. The results were tested against an automated
fusion tool (Syntegra). More than half of the patients had moved during SPECT scanning
(Reviewer 1: 29 patients; Reviewer 2: 30 patients) and they all originated in the
Y-direction translation (vertical hand motion). Five fused images had significant
misalignment errors that could have led to misdiagnosis. The Wilcoxon test indicated
statistically non-significant difference (P > 0.05) between reviewers and statistically
non-significant difference between the reviewers and software registration. The study
also showed high inter-reviewer agreement (κ = 0.87). Hand movement during the SPECT
scan was common, but significant misalignments and subsequent misdiagnosis were infrequent.
Future studies should investigate the use of hand and wrist immobilization devices
and reductions of scan time to minimize patient motion.
Keywords
Image fusion - registration - single photon emission computed tomography/computed
tomography
