Hepatocellular carcinoma: multidetector row helical CT

Hepatocellular carcinoma (HCC) usually is a hypervascular tumor [1–3], and helical computed tomography (CT) has improved detection sensitivity of HCC because it can obtain biphasic (hepatic arterial dominant and portal venous dominant) images during separate breath-holds [4–8]. Many investigators have initiated arterial phase imaging with a scan delay of 20–30 s [4–10]. However, the determination of the optimal timing for the arterial dominant set of images is difficult because it can be influenced by numerous variables, such as the patient’s size and cardiovascular status. Helical CT data with thinner sections has been reported to have better detection sensitivity of hypervascular HCCs [11]. However, when using single-detector row helical CT, extended pitch must be employed to obtain thin-slice images of the entire liver during a single breath-hold, and approximately 25 s was needed to cover the entire liver. Multidetector row helical CT is a newly developed helical CT scanner that can acquire multiple CT data sets with each rotation of the x-ray tube [12] and scan through large anatomic areas three to ten times faster than singledetector row helical CT scanners. Thus, this system can scan through the entire liver in 10 s or less with thinner section collimation than the single-slice helical CT scanner, and two separate sets of CT images of the liver within the period generally regarded as the hepatic arterial dominant phase can be obtained during a single breath-hold [13]. These imaging techniques are expected to reduce the temporal misregistration of the arterial phase scan and improve the diagnosis of HCC. Moreover, the helical CT data with thin-section collimation and three-dimensional displays could demonstrate the major visceral arteries [14–17]. Multidetector row helical CT can obtain thinner section collimation with higher temporal resolution than the single-slice helical CT scanner. These images are thought to be useful for reconstruction in three-dimensional CT angiography, which is helpful for vascular anatomic information and vascular invasion of HCC. With this article, we introduce our technique for liver imaging with multidetector row helical CT and discuss its efficacy for the diagnosis of HCC.