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*

PURPOSE: To determine the enhancing patterns of hepatocellular carcinoma(HCC) and the difference of enhancing patterns according to the tumor size, using spiral CT. MATERIALS & METHODS: We reviewed 213 lesions in 76patients who had been clinically or histopathologically diagnosed as HCC sufferer. The tumors were divided into three groups, according to size(&3 cm, 3-5cm and >5 cm). The enhancing patterns of tumor and capsule in the earlyand delayed phase were analysed. The enhancing patterns of the tumor were divided into five types(high, peripheralhigh, mixed, iso and low attenuation) in the early phase and four types(central high, mixed, iso, and low attenuation) in the delayed phase. The enhancing patterns of the capsule were divided into three types such asiso, low and high attenuation. RESULTS: High attenuating lesions in the early phase were as follows : below 3cm 72% ; 3-5cm., 60% ; above 5cm., 49%. Mixed attenuating lesions in the early phase were as follows : below 3cm., 1%; 3-5cm., 22% ; above 5cm., 36%. Thus, most HCCs were high attenuation type in the early phase, but as the tumorbecame larger, less high attenuation and more mixed attenuation was demonstrated(p<0.01). There was no difference of enhancing patterns according to the tumor size in peripheral high, iso and low-attenuating lesions. In the delayed phase most of the hepatomas appeared as totally hypodense lesions. For capsules, the results were as follows : below 3cm., 20% ; 3-5cm.,58% ; above 5cm., 73%. As the tumors became larger, more capsules were demonstrated(p <0.01). The capsules were visualized as iso or low attenuating rim in the early phase and high attenuating rim in the delayed phase. CONCLUSIONS: To determine the enhancing patterns of HCC using spiral CT is considered to be helpful in the diagnosis of HCC.
Capsules ; Carcinoma, Hepatocellular* ; Diagnosis ; 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 evaluate the usefulness of dynamic spiral computed tomography(CT) during the portal phase with ahigher IV injection rate of contrast material in detecting hepatic metastases. MATERIALS AND METHODS: We reviewed two-phase dynamic spiral CT in 44 patients with hepatic metastases of pathologically proven primary malignancy. One hundred and fifty ml. of non-ionic contrast material was administered with a power injector at a rate of 5ml/sec., and two-phase images at 55-80 sec.(portal phase) and 2-5 min.(equilibrium phase) were obtained after thestart of bolus injection. Two phase images were compared for detectability of hepatic metastases according tosize, number and enhancement pattern. RESULTS: In cases of metastases less than 1cm, 113 lesions(100%) that showed clearly defined hypodense lesions were detected in the portal phase of dynamic CT. However, the equilibriumphase images showed hypodense lesions in 58 cases(51%) and isodense lesions in 55cases(49%). In cases of metastases 1-2cm in size, the portal phase images detected 70 hypodense lesions(92%) and six hyperdense lesions(8%). In the equilibrium phase, however, the lesions were hypodense in 54 cases(71%), hyperdense infour(5%), and isodense in 18(24%). In cases of metastases larger than 2 cm, portal phase images showed 29 hypodense lesions(97%) and one hyperdense lesion(3%). In the equilibrium phase, however, the lesions were hypodense in 25 cases(83%), hyperdense in two(7%), and mixed in three(10%). As compared with the portal phase, most metastatic lesions were detected as poorly defined hypodense or isodense lesions in the equilibrium phase and decrease in size due to peripheral enhancement. CONCLUSION: Dynamic spiral CT during the portal phase with a higher IV injection rate(5 ml/sec) of contrast material is a useful method for detecting hepatic metastases, especially small lesions less than 1cm.
Humans ; Liver* ; Neoplasm Metastasis* ; Tomography, Spiral Computed*

PURPOSE: To determine the different of enhancement patterns of hepatic hemangioma according to the lesionsize, using dual-phase spiral CT. MATERIALS AND METHODS: Fify-nine lesions in 45 patients with hepatichemangiomas were subjected to spiral Ct. According to size, the lesions were divided into two groups(< 2.5cm :n=34 ; >_2.5cm : n=25). The enhancement patterns of the lesions were classified as one of four types (homogeneoushyperdense, peripheral hyperdense, central hyperdense, or hypodense) during the early phase, and as one of fivetypes homogeneous hyperdense, peripheral hyperdense, central hyperdense, hypodense or isodense) during the delayedphase. We evaluated differences in enhancement patterns during the early and delayed phase according to lesionsize. RESULTS: During the early phase, the enhancement patterns of lesions large than 2.5cm were peripheralhyperdense(96%) or homogeneous hyperdense (4%);those of less than 2.5cm were peripheral hyperdense (53%),homogeneous hyperdense(26%), hypodense(18%), or central hyperdense(3%). Thus, hemangiomas in these two groupsusually showed a peripheral enhancement pattern during the early phase, but in those which were smaller than2.5cm, atypical enhancement patterns were more common. During the delayed phase, the enhancement patterns oflesions larger than 2.5cm were peripheral hyperdense (60%) or homogenous hyperdense (40%), while the patterns ofthose smaller than 2.5cm were homogeneous hyperdense (67%), peripheral hyperdense (24%), central hyperdense (3%),hypodense (3%), or isodense (3%). Thus, the enhancement patterns of lesions larger than 2.5cm were usuallyperipherally hyperdense during the delayed phase, while those smaller than 2.5cm showed a homogeneous enhancementpattern. CONCLUSION: The enhancement patterns of hepatic hemangiomas differ according to lesion size. A knowledgeof these differences is helpful in the diagnosis of hepatic hemangioma.
Diagnosis ; Hemangioma* ; Humans ; Tomography, Spiral Computed*

PURPOSE: To evaluate the efficacy of two-phase dynamic helical CT, including the gastric mucosal phase, for the detection of atypical non-hyperattenuating early gastric carcinoma (EGC). MATERIALS AND METHODS: In 32 patients, we evaluated the two-phase helical CT findings of endoscopically suspected EGC for changes of the inner hyperattenuating mucosal layer, the hypoattenuating outer layer and the serosal surface. Two gastrointestinal radiologists working together reached their conclusions before pathologic diagnosis had been made. The first, so-called gastric mucosal, phase was obtained 38 -45 sec after the start of IV injection of 150 ml/sec contrast material at a rate of 4 ml/sec to obtain maximum enhancement of the mucosal layer. RESULTS: Among 32 patients, EGC was confirmed in 30 and AGC (T2) in two. Using two-phase helical CT, the detection rate for typical hyperattenuating EGC was 27 % (8/30). Lesions showing focal interruption of the mucosal layer without abnormal enhancement of the outer layer (EGC atypical enhancement pattern type 1) were detected in five patients during the mucosal phase, and were pathologically confirmed as 3 EGC IIc+III, 1IIc+IIa, and I IIb+IIc. Lesions showing a locally protuding lesion of the inner and preserved outer layers, with a smooth serosal surface (EGC atypical enhancement pattern type 2) and which could be distinguished from normal folds, were detected in six patients during the mucosal phase, and were pathologically confirmed as 2 EGC IIb+IIc, 1 IIc+IIa, and 3 IIc+IIb. Lesions were less distinct during the equilibrium phase, and there was no change in the enhancement pattern. The overall detection rate for EGC in which an atypical enhancement pattern was added to the typical one showed improvement (19/30, 63 % ). CONCLUSION: Helical CT using a two-phasic scan technique including the mucosal phase was efficient for various combinations of EGC II and/or III, including IIc. The findings were atypical and non-hyperattenvating, but reliable, and improved the overall detection rate.
Diagnosis ; Humans ; Stomach Neoplasms* ; Tomography, Spiral Computed*

PURPOSE: To compare virtual gastroscopy using spiral CT with conventional endoscopy for the detection andevaluation of gastric lesions. MATERIALS AND METHODS: During a previous six-month period, 30 patients withpathologically-proven gastric lesions underwent conventional endoscopy and virtual gastroscopy using spiral CT.There were 18 cases of advanced gastric carcinoma, eight benign ulcers, and four submucosal tumors(two leiomyomas,two lymphomas). Source images of virtual gastroscopy were three-dimensionally reconstructed within an AdvantageWindows Workstation and virtual gastroscopy images were obtained using Navigator Software. On analysis, imageswere graded according to their quality (excellent, good, poor). Virtual gastroscopy images were interpreted by tworadiologists blinded to conventional endoscopic findings, and were subsequently compared with endoscopic findingsin terms of detectability and findings. In the cases of advanced gastric carcinoma, lesions were classifiedaccording to Borrmann's system. RESULTS: For virtual gastroscopy, overall image quality was excellent in 21cases(70%), good in five(17%), and poor in four(13%). Lesions were detected in 25 cases(83%). Among the 18advanced gastric carcinomas, virtual gastroscopy image quality was excellent in 14 cases(78%), good in two(11%),and poor in two(11%). Lesions were detected in 16 cases(89%). Two Borrmann type IV cases were not detected. Amongthe eight benign ulcers, virtual gastroscopy image quality was excellent in three cases(38%), good in three(38%),and poor in two(25%). The detection of lesion was possible in five cases(63%). In all submucosal tumors, virtualgastroscopy image quality was excellent. Lesions were detected in all cases. CONCLUSION: Virtual gastroscopyusing spiral CT is safe and noninvasive, and for the evaluation of gastric lesions may be complementary to axialCT. It successfully detects gastric lesions, and in depicting the pattern of gastric folds its image quality isexcellent.
Endoscopy ; Gastroscopy* ; Humans ; Tomography, Spiral Computed* ; Ulcer

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*