Put your thinking HAT on... Pulsed-Wave Doppler Ultrasound Characteristics of a Hepatic Artery Thrombosis.
Lorraine Healy1,2, Kristine Gallagher2, Therese Herlihy1, 1Radiography and Diagnostic Imaging, School of Medicine, University College Dublin, Ireland, 2Radiology Department, St. Vincent’s University Hospital, Elm Park, Dublin 4, Ireland
Background:
This case study describes the ultrasound findings of a 54 year old female who presented to the ultrasound department with raised liver enzymes, eight weeks post-orthotopic liver transplant (OLT). The immediate post-operative ‘Ducts and Doppler’ ultrasound examination showed no evidence of vascular complications and her recovery was uneventful. Upon presentation eight weeks later, the ultrasound examination demonstrated a late post-procedural hepatic artery thrombosis (HAT).
Case Report:
Doppler ultrasound imaging demonstrated an extra-hepatic artery with areas of aliased colour filling tapering to an area void of colour filling. A ‘tardus-parvus’ waveform was detected in the intra-hepatic segment of the common hepatic artery and right intra-hepatic artery. Left hepatic arterial flow was absent. Arterial resistive index (RI) and systolic acceleration time (SAT) were both indicative of an occlusion (RI ?0.5, SAT >0.08s, classic tardus-parvus waveform, absent flow of the left hepatic artery). Furthermore, a collateral arterial supply to the RHA was detected. CT corroboration imaging showed a stable hepatic artery thrombosis with a small intra-hepatic collateral arterial branch formation.
Discussion:
Ultrasound is utilised as the first-line imaging modality when assessing liver vascularity post-OLT. Spectral and colour Doppler ultrasound have a crucial role in the diagnosis of HAT. In this case, an arterial complication was ultrasonically diagnosed due to an aliasing common hepatic artery tapering to an area void of colour flow. Downstream, Spectral Doppler demonstrated a ‘tardus-parvus’ waveform. The left hepatic artery demonstrated no flow. Doppler ultrasound has both a high sensitivity (54% to 92%) and specificity (64% to 88%) in the diagnosis of HAT. Correct operator technique is crucial for accurate measurements and every