Use of spectral CT with fast tube voltage switching may increase the sensitivity for differentiating small hemangiomas from small HCCs in two-phase scanning.

• Spectral computed tomography may help the detection of small hepatocellular carcinoma. • Monochromatic energy levels of 40-70 keV increase the sensitivity for detection. • Prospective study showed that monochromatic imaging provides greater diagnostic confidence. • Monochromatic energy level of 70 keV improves the overall image quality.

• Automatic spectral imaging protocol selection provides appropriate scan protocols. • Abdominal CT is feasible using spectral imaging and 300 mgI/kg contrast agent. • 50-keV monochromatic images with 50 % ASIR provide optimal image quality.

ObjectiveTo investigate the value of spectral CT imaging in the diagnosis and classification of liver cirrhosis during the arterial phase (AP) and portal venous phase (PVP).Materials and MethodsThirty-eight patients with liver cirrhosis (Child-Pugh class A/B/C: n = 10/14/14), and 43 patients with healthy livers, participated in this study. The researchers used abdominal spectral CT imaging during AP and PVP. Iodine concentration, derived from the iodine-based material-decomposition image and the iodine concentration ratio (ICratio) between AP and PVP, were obtained. Statistical analyses {two-sample t test, One-factor analysis of variance, and area under the receiver operating characteristic curve (A [z])} were performed.ResultsThe mean normalized iodine concentration (NIC) (0.5 ± 0.12) during PVP in the control group was significantly higher than that in the study group (0.4 ± 0.10 on average, 0.4 ± 0.08 for Class A, 0.4 ± 0.15 for Class B, and 0.4 ± 0.06 for Class C) (All p < 0.05). Within the cirrhotic liver group, the mean NIC for Class C during the AP (0.1 ± 0.05) was significantly higher than NICs for Classes A (0.1 ± 0.06) and B (0.1 ± 0.03) (Both p < 0.05). The ICratio in the study group (0.4 ± 0.15), especially for Class C (0.5 ± 0.14), was higher than that in the control group (0.3 ± 0.15) (p < 0.05).The combination of NIC and ICratio showed high sensitivity and specificity for differentiating healthy liver from cirrhotic liver, especially in Class C cirrhotic liver.ConclusionSpectral CT Provides a quantitative method with which to analyze the cirrhotic liver, and shows the potential value in the classification of liver cirrhosis.

ObjectiveTo determine whether or not detailed cystic feature analysis on CT scans can assist in the differential diagnosis of pancreatic ductal adenocarcinoma (PDAC) from serous cystadenoma (SCN), mucinous cystadenoma (MCN), and a pseudocyst.Materials and MethodsThis study received Institutional Review Board approval and informed patient consent was waived. Electronic radiology and pathology databases were searched to identify patients with PDAC (n = 19), SCN (n = 26), MCN (n = 20) and a pseudocyst (n = 23) who underwent pancreatic CT imaging. The number, size, location, and contents of cysts, and the contour of the lesions were reviewed, in addition to the wall thickness, enhancement patterns, and other signs of pancreatic and peripancreatic involvement. Diagnosis was based on lesion resection (n = 82) or on a combination of cytological findings, biochemical markers, and tumor markers (n = 6). Fisher's exact test was used to analyze the results.ResultsA combination of the CT findings including irregular contour, multiple cysts, mural nodes, and localized thickening, had a relatively high sensitivity (74%) and specificity (75%) for differentiating PDAC from SCN, MCN, and pseudocysts (p < 0.05). Other CT findings such as location, greatest dimension, or the presence of calcification were not significantly different.ConclusionThe CT findings for PDAC are non-specific, but perhaps helpful for differentiation. PDAC should be included in the general differential diagnosis of pancreatic cystic neoplasms.

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