LIVER PERFUSION STUDIED WITH ULTRAFAST CT

Objective: Our goal was to quantify absolute hepatic arterial and port al venous perfusion noninvasively in patients with and without liver d isease using ultrafast CT. Materials and Methods: A single slice throu gh the porta hepatis was repeatedly scanned after bolus injection of 2 5 ml of iohexol 300 mg I/ml, followed by a 25 ml saline ''chaser'' int ravenously at 10 ml/s. Thirty-nine controls, 7 cirrhotic patients, and 5 patients with known metastases on the slice plane were studied; hep atic arterial perfusion was determined in 41 patients and portal venou s perfusion in 24. Time-attenuation curves from regions of interest dr awn over the liver, spleen, aorta, and portal vein were analysed. Hepa tic arterial perfusion was calculated by dividing the peak gradient of the liver time-attenuation curve prior to the time of peak splenic at tenuation by the peak aortic CT number increase. Splenic perfusion was calculated by dividing the peak gradient of the splenic time-attenuat ion curve by the peak aortic CT number increase. Portal perfusion was derived by scaling the splenic time-attenuation curve by the ratio of hepatic arterial/splenic perfusion. This scaled curve was subtracted f rom the liver time-attenuation curve to give a portal curve, The peak up-slope of this curve was divided by the peak rise in splenic or port al vein density. Results: Hepatic arterial perfusion averaged 0.,19 ml /min/ml (n = 31) in controls and was raised in cirrhosis to 0.25 ml/mi n/ml(n = 6) and metastases 0.43 ml/min/ml(n = 4). Portal venous perfus ion was 0.93 ml/min/ml (n = 19) in controls and 0.43 ml/min/ml (n = 4) in cirrhosis, Reproducibility has been confirmed. Conclusion: Dynamic ultrafast CT shows potential in quantifying arterial and portal hepat ic perfusion. The technique may be adaptable to dynamic bolus MRI.