Multi-slice spiral CT has been an outstanding progress in developmental history of CT technology. The technical indexes of all three respects, ie scanning range time and spatial resolution are all marked improved. And several robust post-processing techniques have been imported into CT data post-scanning reconstruction, which help massive volume data being sufficiently and optimally interpreted. Therefore, newer advances have been achieved both in clinical applications and diagnostic efficacy.
Tomography, Spiral Computed ; methods

PURPOSE: To evaluate contrast enhancement patterns of hemangioma according to size, as seen during thearterial and portal venous phase of spiral CT. MATERIAL AND METHODS: During a recent six month-period, 52patients with hemangiomas underwent two-phase spiral CT examination with 10mm collimation at 10mm/sec table speed,and with 100mL of contrast material(37g iodine) injected at a rate of 2.5 mL/sec. CT images of the hepaticarterial and portal venous phase were obtained with 30-second and 65-second delay, respectively. In 52 patients,82 hemangiomas were seen. The diameter of the tumors were as follows ; < or =10 mm(n=31), 11-20 mm(n=19), and> or =21mm(n=32). The enhancement patterns of tumors compared with attenuation of surrounding liver parenchyma weredivided into four types : peripheral high, uniform high, iso, and low. RESULTS: Overall, the most commonenhancement pattern was peripheral high(44/82, 53.7%), during the arterial and portal venous phase. The second andthird most common patterns were uniform high(11/82, 13.4%) and peripheral high-uniform high(9/82, 11.0%), alsoduring the arterial and portal venous phase. Sixty-one(74.4%) showed peripheral high attenuation andeleven(13.4%), uniform high attenuation, during the arterial and/or portal venous phase. In tumors smaller than20mm, low-low attenuation was seen in eight(9.8%), and iso-low attenuation in two(2.4%), during the arterial andportal venous phase, respectively. CONCLUSION: On two-phase spiral CT, the most common enhancement pattern ofhemangioma was peripheral high, seen during the arterial and portal venous phase. However, a small hemangioma lessthan 2 cm may show atypical patterns, including low and iso attenuation.
Hemangioma* ; Liver ; Tomography, Spiral Computed*

The number of CT examinations is dramatically increasing due to recent technical advances including multi-slice spiral CT. Although the benefits of CT outweigh the risks of radiation exposure of CT, radiologists should alert to the potential harmful effects of CT and avoid unnecessarily high CT dose, especially for pediatric CT examinations. To accomplish this, we should understand CT radiation dose and be familiar with imaging techniques of reducing CT dose without degrading diagnostic image quality. In addition, it is important to spread this balanced and useful information into CT referring clinicians, radiologists in training, and medical students.
Humans ; Students, Medical ; Tomography, Spiral Computed

PURPOSE: To assess, by means of CT-pathologic correlation, the ability of CT to detect hepatic VX-2 carcinomas in rabbits, and to determine the factors influencing the sensitivity of tumor detection. MATERIALS AND METHODS: By means of direct portal inoculation, VX-2 carcinomas were implanted in the liver of eight rabbits after laparotomy. Two weeks later, dual-phase spiral CT scanning was performed using scan parameters of 3-mm collimation and reconstruction intervals of 1 mm and 3 mm. Radiologic-pathologic correlation involved the comparison of CT images and pathologic slices. The sensitivity and positive predictive value with which each technique detected the presence of tumors were calculated. RESULTS: Using pathologic slices, 2-40 (mean, 9.1) mm in size, 65 tumor nodules were detected. Overall sensitivity and the positive predictive value were 63% and 73%, respectively. Sensitivities for tumors of 2-5 mm and 6-10 mm were 28% and 79%, respectively. For images reconstructed with a 1-mm interval, sensitivity was significantly higher than that where a 3-mm interval was used (79% vs. 46%), but sensitivities for arterial and portal-phase imaging were not significantly different. Among small tumors (< or = 10 mm), 63% (12/19) showed strong enhancement at arterial-phase imaging. Regarding tumor detection, inter-observer concordance between the three radiologists was excellent for portal-phase images (k=0.86 and 0.83 for 1 mm and 3 mm reconstruction intervals, respectively), and good for arterial-phase images (k=0.77 and 0.73 for 1 mm and 3 mm reconstruction intervals, respectively. CONCLUSION: Even where dual-phase scanning with 3-mm collimation is used, spiral CT is limited in its ability to detect tumors 5 mm or less in diameter, though overlapping reconstruction improves the sensitivity with which those of 6-10 mm are detected. In the evaluation of arterial-phase images obtained at contrast-enhanced dual-phase imaging, special attention should be given to small hyper-attenuating nodules.
Animals ; Laparotomy ; Liver ; Rabbits ; Tomography, Spiral Computed*

PURPOSE: To evaluate the characteristics of contrast enhancement of peripheral cholangiocarcinoma, as seen on spiral CT. MATERIALS AND METHODS: Spiral CT was used to examine twelve patients with peripheral cholangiocarcinoma of the liver. All underwent conventional CT before contrast enhancement. After the administration of contrast material, two-phased spiral CT was used to investigate seven patients, and three-phased spiral CT, to investigate five. In each phase, we analysed the patterns of contrast enhancement at the central and peripheral portions of the lesion, and compared these with the patterns of normal liver parenchyma. We evaluated changes, according to time lapse, in the central low-density area, and obtained the phase-density curve with the cursor placed at the central portion of the lesion. For three-phased spiral CT examinations, we also tried to determine the phase dvring which the margin of the lesion was most clearly demonstrated. RESULTS: During the arterial phase, eight of twelve patients (67%) showed hyperdensity in the peripheral portion of the lesion; during the portal phase, four of five patients (80%) showed hypodensity in both the central and peripheral portions. During the delayed phase, six of twelve patients (50%) showed isodensity and five showed high density in the peripheral portion. Compared to those in the arterial phase, central hypodense areas relative to normal liver parenchyma in the delayed phase decreased in eleven of twelve patients (92%). On phase-density curves, the density of the central portion of the lesion increased progressively in nine of twelve patients (75%). On three-phased CT, the margin of lesion was-in all five patients - most clearly demonstrated in the portal phase. CONCLUSION: On spiral CT, the central portion of peripheral cholangiocarcinoma always showed low density and the peripheral portion showed high, low, or iso or high density, depending on the phase. In addition, spiral CT clearly demonstrated a minimal centripetal pattern of contrast enhancement. We therefore conclude that in the diagnosis of peripheral cholangiocarcinoma, the characteristics of contrast enhancement are helpful.
Cholangiocarcinoma* ; Diagnosis ; Humans ; Liver ; Tomography, Spiral Computed*

PURPOSE: To determine the incidence of hepatic hemangiomas associated with wedge-shaped parenchymal enhancements adjacent to the tumors as seen on two-phase spiral CT images obtained during the hepatic arterial phase and to characterize the two-phase spiral CT findings of those hemangiomas. MATERIALS AND METHODS: One hundred and eight consecutive hepatic hemangiomas in 63 patients who underwent two-phase spiral CT scanning during an 11-month period were included in this study. Two-phase spiral CT scans were obtained during the hepatic arterial phase(30-second delay) and portal venous phase(65-second delay) after injection of 120mL of contrast material at a rate of 3mL/sec. We evaluated the frequency with which wedge-shaped parenchymal enhancement was adjacent to the hemangiomas during the hepatic arterial phase and divided hemangiomas into two groups according to whether or not wedge-shaped parenchymal enhancement was noted (Group A and Group B). The presence of such enhancement in hemangiomas was cor-related with tumor size and the grade of intratumoral enhancement. RESULTS: In 24 of 108 hemangiomas, wedge-shaped parenchymal enhancement adjacent to hepatic tumors was seen on two-phase CT images obtained during the hepatic arterial phase. Mean hemangioma size was 22mm in Group A and 24mm in Group B. There was no statistically significant relationship between lesion size and the presence of wedge-shaped parenchymal enhancement adjacent to a hemangioma. In 91.7% and 1 00% of tumors in Group A, and in 9.6% and 17.8% in Group B, hemangiomas showed more than 50% intra-tumoral enhancement during the arterial and portal venous phase, respectively. Wedge-shaped parenchymal enhancements peripheral to hepatic hemangiomas was more frequently found in tumors showing more than 50% intratumoral enhancement during these two phases(p<0.01). CONCLUSION: Wedge-shaped parenchymal enhancements is not uncommonly seen adjacent to hepatic heman-giomas on two-phase spiral CT images obtained during the hepatic arterial phase. A hemangioma showing-wedge-shaped parenchymal enhancement tends to show more than 50% intratumoral enhancements during the arterial and portal venous phase.
Hemangioma* ; Humans ; Incidence ; Tomography, Spiral Computed*

PURPOSE: To determine the frequency and patterns of respiratory-induced misregistration artifact seen on spiral CT of the liver. MATERIALS AND METHODS: Two hundred patients with hepatic mass underwent spiral CT, and arterial phase images were compared with those of the portal phase in all cases and or of the delayed phase in 138. The patterns of misregistration artifact were divided into two groups: skipping, where at least two slices in the craniocaudal length of the mass were missed, and the partial volume veraging artifact thus excluded; and overlapping, where the same or reversed images were seen in succeeding sequences. We reviewed the location and size of the masses, and the presence or absence, and patterns of the misregistration artifact. RESULTS: Fourteen (7%) of 200 spiral CT scans demonstrated the misregistration artifact; in five of these there was skipping (involving a hepatic mass larger than 2 cm in two cases, and one smaller than 2 cm in three cases), and in nine there was overlapping (six masses larger than 2 cm, and three smaller than this). A lipiodol-laden mass measuring 5 mm was completely missed during the arterial phase. and in one case the spleen sequence was reversed. Thirteen (93%) of fourteen masses were located in the right lobe. CONCLUSION: Two patterns of misregistration artifact, skipping and overlapping, were observed, and their combined frequency was 7%. So as not to miss small hepatic masses or overestimate their size, careful respiratory control is therefore needed.
Artifacts* ; Humans ; Liver* ; Spleen ; Tomography, Spiral Computed*

PURPOSE: To investigate the role of 3D imaging in the sinonasal mass. MATERIALS AND METHODS: Twenty patients with sinonasal mass(squamous cell carcinoma[n=6], spindle cell carcinoma[n=1}, angiomatous polyp[n=1}, giant cell reparative granuloma[n=1}, non-Hodgkin's lymphoma[n=1}, melanoma[n=1}, angiofibroma[n=1}, pyocele[n=1}, inverted papilloma[n=1}) were studied with spiral CT. Reconstruction of surface rendered 3D images and segmentations were performed and compared with the 2D image. RESULTS: The 3D images enabled easy understanding of the characteristics of the mass in 12 casese. The 3D images displayed pathway of tumor extension in 5 cases and werehelpful in assessing the primary site of the mass in 3 cases. In two cases with encasement of ICA by the mass, assesment of relationship between the mass and vessels were possible through the segmentation. CONCLUSION: The 3D image, as an adjunct to the 2D image, can help to evaluate the virtual appearance of bony change, the degree of extension of mass, the spreading route, the evaluation of origin site. It also provides valuable 3-dimensional conception of the mass, especially for the surgeon.
Imaging, Three-Dimensional* ; Tomography, Spiral Computed

We report a case of Rasmussen aneurysm diagnosed by helical CT that well shows vascular imaging. Coil embolization of Rasmussen aneurysm stopped the bleeding successfully.
Aneurysm* ; Embolization, Therapeutic* ; Hemorrhage ; Tomography, Spiral Computed*

PURPOSE: To determine whether triple-phase multi-detector-row helical CT images of the liver improves the detection rate of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Forty-one patients with 103 HCCs underwent triple-phase multi-detector-row helical CT imaging of the entire liver after contrast administration. Early and late arterial phase images were obtained serially during a single breath-hold, and portal venous-phase images were then obtained. Each image set was independently assessed for the presence of HCC by two radiologists unaware of the possible presence of tumors, and for each phase the detection rate was determined. For each arterial-phase image, lesion conspicuity (attenuation of a tumor compared with that of its parenchyma) was calculated. RESULTS: For reader 1, the detection rates for the early arterial, late arterial, and portal venous phase were 81%, 77%, and 55%, respectively, and for reader 2 were 83%, 81%, and 68%, respectively (p>0.05). When triplephase imaging findings were combined, the detection rate was significantly higher than when only those of the early or late arterial, and portal venous, phase were used (p<0.05). Mean lesion conspicuity for the late arterial phase was higher than for the early arterial phase, but the difference was statistically insignificant (p>0.05). CONCLUSION: Triple-phase imaging of the liver, involving the early arterial, late arterial, and portal venous phase, and using multi-detector-row helical CT, increases the detection rate of HCC.
Carcinoma, Hepatocellular ; Humans ; Liver* ; Tomography, Spiral Computed*