Optimizing liver contrast in helical liver CT: value of a real-time bolus-triggering technique

• Published in: European radiology 1998-01, Vol.8 (9), p.1608-1612
• Main Authors: Dinkel, H P, Fieger, M, Knüpffer, J, Moll, R, Schindler, G
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Contrast Media - administration & dosage; Female; Humans; Image Enhancement - methods; Image Processing, Computer-Assisted; Injections, Intravenous; Iopamidol - administration & dosage; Iopamidol - analogs & derivatives; Liver - diagnostic imaging; Liver Diseases - diagnostic imaging; Male; Middle Aged; Portal Vein - diagnostic imaging; Prospective Studies; Software; Time Factors; Tomography, X-Ray Computed - methods
• ISSN: 0938-7994; 1432-1084
• DOI: 10.1007/s003300050596

Optimal liver enhancement during portal venous-phase helical CT is crucial in the detection of parenchymal liver lesions. In the prospective study reported here we investigated the effects of a real-time bolus-tracking system on mean and maximal liver enhancement. In 79 patients referred to us for abdominal CT we injected 120 ml of non-ionic contrast (300 mg I/ml) at a rate of 3 ml/s. After a nonintravenous contrast upper abdominal scan a portal venous phase was performed. In 39 patients (mean weight 72.6 +/- 18.7 kg, range 48-139 kg) real-time bolus tracking was performed using the CARE Bolus software (Siemens, Erlangen, Germany). The software performs repetitive low-dose test scans in a preselected region of interest and measures the Hounsfield attenuation and liver enhancement in real-time. After a critical threshold (we selected 31 HU) is surpassed, the software starts diagnostic spiral scanning. Our control consisted of 40 patients weighing 51-100 kg (mean 73.2 +/- 11.1 kg) who were scanned with a fixed, preselected start delay of 80 s. Mean hepatic enhancement was 54.0 +/- 9.9 HU (range 33.3-74 HU) in 37 automatically triggered patients, mean peak hepatic enhancement 64.6 +/- 12.6 HU (range 42.0-91.8 HU). In 2 patients of the study group scanning had to be started manually. In the control group with fixed delay mean enhancement was 48.3 +/- 9.2 HU (range 33.8-71.6 HU) and peak enhancement 55.5 +/- 9.7 HU (range 39.7-81.0 HU). Differences were significant (p < 0.05, Student's t-test). Real-time bolus tracking significantly increased mean hepatic enhancement and may improve portal venous hepatic CT scanning.