Haemorrhage and Calcification on Susceptibility-Weighted Imaging

Abstract

Haemorrhage and calcification can be qualitatively distinguished on susceptibility-weighted imaging (SWI) using phase information, but it is unclear how to make this distinction in a subset of lesions with ambiguous phase, containing a mixture of positive and negative values. This work investigates the validity of qualitative phase assessment at the cranial or caudal margins in classifying such lesions as haemorrhagic or calcific, when quantitative susceptibility mapping is not available to the neuroradiologist. In a retrospective review of magnetic resonance imaging examinations acquired between July 2015 and November 2019, 87 lesions with ambiguous phase which could be confidently determined to be haemorrhagic or calcific were identified. Two blinded neuroradiologists independently classified these lesions as haemorrhagic or calcific using 3 approaches: qualitative phase assessment at the lesions’ cranial or caudal margins, dominant phase, and in-plane margins. Combined sensitivities and specificities of these analyses were calculated using a generalised linear mixed model with random effects for reader. Assessment at the cranial or caudal margins achieved a sensitivity of 100% for haemorrhage and calcification, which was significantly superior (p\u202f<\u20090.05) to dominant phase assessment with sensitivities of 52% for haemorrhage (95% confidence interval, CI 43–61%) and 54% for calcification (95% CI 42–66%), as well as in-plane margin assessment with 28% (95% CI 18–38%) and 46% (95% CI 36–56%). Haemorrhage and calcification can be reliably distinguished in lesions with ambiguous phase on SWI by qualitative review of the phase signal at the cranial or caudal margins.