Optimal scan timing of hepatic arterial-phase imaging of hypervascular hepatocellular carcinoma determined by multiphasic fast CT imaging technique

Abstract

A new multiphasic fast imaging technique, known as volume helical shuttle technique, is a breakthrough for liver imaging that offers new clinical opportunities in dynamic blood flow studies. This technique enables virtually real-time hemodynamics assessment by shuttling the patient cradle back and forth during serial scanning. To determine optimal scan timing of hepatic arterial-phase imaging for detecting hypervascular hepatocellular carcinoma (HCC) with maximum tumor-to-liver contrast by volume helical shuttle technique. One hundred and one hypervascular HCCs in 50 patients were prospectively studied by 64-channel multidetector-row computed tomography (MDCT) with multiphasic fast imaging technique. Contrast medium containing 600 mg iodine per kg body weight was intravenously injected for 30 s. Six seconds after the contrast arrival in the abdominal aorta detected with bolus tracking, serial 12-phase imaging of the whole liver was performed during 24-s breath-holding with multiphasic fast imaging technique during arterial phase. By placing regions of interest in the abdominal aorta, portal vein, liver parenchyma, and hypervascular HCCs on the multiphase images, time-density curves of anatomical regions and HCCs were composed. Timing of maximum tumor-to-liver contrast after the contrast arrival in the abdominal aorta was determined. For the detection of hypervascular HCC at arterial phase, mean time and value of maximum tumor-to-liver contrast after the contrast arrival were 21 s and 38.0 HU, respectively. Optimal delay time for the hepatic arterial-phase imaging maximizing the contrast enhancement of hypervascular HCCs was 21 s after arrival of contrast medium in the abdominal aorta.