Usefulness of Multidetector-row CT in the Evaluation of Reperfused Myocardial Infarction in a Rabbit Model

OBJECTIVE: To evaluate the usefulness of multidetector-row computed tomography (CT) in the evaluation of reperfused myocardial infarction. MATERIALS AND METHODS: Eleven rabbits were subjected to 90-min occlusion of the left anterior descending coronary artery followed by reperfusion. Multidetector-row CT was performed 31 hours+/-21 after the procedure and preand post-contrast multiphase helical CT images were obtained up to 10 min after contrast injection. The animals were sacrificed after 30 days and histochemical staining of the resected specimens was perfomed with 2'3'5-triphenyl tetrazolium chloride (TTC). RESULTS: In all 11 cases, the areas of myocardial infarction demonstrated with TTC-staining were identified on the CT images and the lesions showed hypoenhancement on the early phases up to 62 sec and hyperenhancement on the delayed phases of 5 min and 10 min compared with normal myocardial enhancement. The percentage area of the lesion with respect to the left ventricle wall on CT was significantly correlated with that of the TTC-staining results (p < 0.001 for both early and delayed phase CT) according to the generalized linear model analysis. The areas showing hypoenhancement on early CT were significantly smaller than those with hyperenhancement on delayed CT (p < 0.0001). CONCLUSION: Multidetector-row CT may be useful in the detection and sizing of reperfused myocardial infarction.

Acute Appendicitis: Sensitivity, Specificity and Diagnostic Accuracy of Thin-Section Contrast-Enhanced CT Findings

PURPOSE: To assess the sensitivity, specificity, and diagnostic accuracy of individual contrast-enhanced helical CT findings of acute appendicitis. MATERIALS AND METHODS: We retrospectively reviewed the appendiceal helical CT scans, obtained after intravenous contrast administration (abdomen; 7-mm collimation, abdominopelvic junction; 5-mm collimation), of 50 patients with surgically proven acute appendicitis and 112 with alternative diagnoses. The following parameters were analysed by three radiologists: enlarged appendix (> 6 mm in diameter), appendiceal wall thickening, appendiceal wall enhancement, no identification of the appendix, appendicolith(s), (appendiceal) intraluminal air, (appendiceal) intraluminal air extraluminal air, periappendiceal fat stranding, extraluminal fluid, phlegmon, abscess, lymphadenopathy, terminal ileal wall thickening, focal cecal apical thickening, focal colonic wall thickening, and segmental colonic wall thickening. RESULTS: The CT findings of acute appendicitis that statistically distinguished it from alternative diagnoses were an enlarged appendix (sensitivity; 92%, specificity; 93%, diagnostic accuracy; 93%), appendiceal wall thickening (for these three parameters: 68%, 96% and 88%, respectively), periappendiceal fat stranding (90%, 79%, 82%), appendiceal wall enhancement (72%, 86%, 82%), appendicolith (16%, 100%, 74%), and focal cecal apical thickening (14%, 100%, 74%) (for each, p < 0.05). CONCLUSION: On thin-section contrast-enhanced helical CT, an enlarged appendix and periappendiceal fat stranding were found in 90% or more patients with acute appendicitis. Appendiceal wall thickening and enhancement were clearly demonstrated and significant findings for diagnosis. Less common but specific findings include appendicolith, focal cecal apical thickening and intramural air, can also help us establish a diagnosis of acute appendicitis.

Analysis of Enhancement Pattern of Sellar and Parasellar Tumors Using Two-Phase Helical CT

PURPOSE: To assess the enhancement patterns of sellar and parasellar tumors at two-phase helical CT. MATERIALS AND METHODS: Thirty-two patients with pathologically proven sellar and parasellar tumors [meningioma (n=17), pituitary mocroadenoma (n=6), neurogenic tumor (n=5), cavernous angioma (n=1), chondrosarcoma (n=1), osteosarcoma (n=1), sphenoid carcinoma (n=1)] were included in this study. Two-phase helical CT was performed after the injection of 90 mL of contrast material at a rate of 3 mL/sec. Transverse helical CT scans were obtained during the early and late phases, with scanning delays of 30 and 120 seconds, respectively. Delayed coronal images were obtained after delayed axial images. Attenuation change and the enhancement patterns of the tumors were visually assessed; the former was also assessed quantitatively as the ratio of the CT number at late-phase axial and coronal scanning to that at early-phase scanning. RESULTS: Visual assessment of two-phase helical CT images revealed decreased attenuation in all 17 meningiomas, no change in all six pituitary macroadenomas and increased attenuation in 5 all five neurogenic tumors on late-phase axial scans as compared with early phase scans. Coronal images showed decreased attenuation in all 17 meningiomas, increased attenuation in all five neurogenic tumors and no change in four pituitary macroadenomas (66.7%). The ratio of CT numbers was significantly different between meningiomas, neurogenic tumors and pituitary macroadenomas(p<0.05). CONCLUSION: According to their histopathology, sellar and parasellar tumors showed characteristic enhancement patterns at two-phase helical CT. An analysis of the observed enhancement patterns can be useful in the differential diagnosis of juxtasellar tumors.

Spiral CT of Hepatocellular Carcinoma: Value of Dynamic Fast Infusion of Contrast Material

PURPOSE: To assess the value of dynamic fast infusion of contrast material in the detection and diagnosis of hepatocellular carcinoma(HCC) with spiral CT. MATERIALS AND METHODS: Two-phase dynamic spiral CT was performed in 59 patients with 104 HCCs. 150ml of nonionic contrast material was injected with an automatic injector at the rateof 5 ml/sec. Two-phase images were obtained at 20-45 sec(arterial dominant phase) and 2-5 min(equilibrium phase)after the initiation of bolus injection of contrast material. The tumors were divided into three groups(5cm) according to the size and the enhancement patterns on two-phase images were compared. RESULTS: Inthe arterial phase, HCCs showed total or partial hyperattenuation in 79% of cases(82/104), isoattenuation in 12%,and hypoattenuation in 9%. In the equilibrium phase, HCCs showed hypoattenuation in 86%(89/104) and isoattenuationin 14%. The most common and characteristic enhancement patterns of HCCs were hyperattenuation in the arterialphase and hypoattenuataion in the equilibrium phase ; in the latter, capsules were demonstrated in 45% of cases. Invasions of the portal and/or hepatic vein were demonstrated in 34% of cases. CONCLUSION: Dynamic fastinfusion(5ml/sec) of contrast material(150ml) is useful in the detection and diagnosis of HCCs with spiral CT.

Contrast Enhancement Characteristics of Hepatocellular Carcinoma According to the Tomor Size on Two-Phase Scan with Spiral CT

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.

Measurement of Total Lung Capacity: A Comparison of Spiral CT and Spirometry

PURPOSE: To determine the potential of spiral CT as a functional imaging modality of the lung asid from its proven value in morphological depiction. MATERIALS AND METHODS: Spiral CT scan was performed in ten normal female and nine normal male adults (mean age: 39, height: 163cm, weight: 62kg) after single full breath-holding. Three dimensional lung images were reconstructed (minimal threshold value: -1,000HU, maximal threshold values: -150,-250, -350, -450HU) to obtain total lung volume(TLV) on a histogram. Total lung volume measured by spiral CT was compared with TLV obtained by spirometry. RESULTS: Mean TLV measured by spirometry was 5.62 Land TLV measured by CT at maximal threshold values of -150, -250, -350, and -450HU was 6.63, 5.33, 5.15, and 4.98 L, respectively. Mean absolute differences between the modalities of 0.17L(3%), 0.32L(5.6%), 0.48L(8.5%), 0.65L(11.5) were statistically significant(p<0.001). Linear regression coefficients between the modalities were 0.99, 0.97, 0.95,and 0.94 and no statistically significant differences in accuracy of threshold levels in the estimation of lung volume(r=0.99, standard error=0.034L in all) were seen. CONCLUSION: TLV measured by spiral CT closely approximated that measured by spirometry. Spiral CT may be useful as a means of evaluating lung function.

Nodular Hepatocellular Carcinoma: Enhancing Patterns in the Arterial- and Portal-dominant Phases of Spiral CT

PURPOSE: To evaluate the enhancing patterns of nodular hepatocellular carcinomas (HCCs) in the arterial-andportal-dominant phases of spiral CT. MATERIALS AND METHODS: A retrospective analysis of enhancing patterns was performed in 100 patients with HCCs diagnosed by pathologic findings (n=30) or clinical and radiological findings. CT images were obtained 30 seconds(arterial-dominant phase) and 65 seconds(portal-dominant phase) after beginning injection of contrast medium (120mL, 3mL/sec). After transarterial chemoembolization, 179 tumors detected oniodized oil-CT were divided into four groups according to their largest diameter, as follows ; group I(smallerthan 1cm, n=51), II(1-2cm, n=46), III(2-3cm, n=32), IV(larger than 3cm, n=50). The enhancing patterns of tumorscompared with attenuation of surrounding liver parenchyma, were divided into four types, namely high, iso, low andmixed. RESULTS: Each group showed a different enhancing pattern ; group I showed iso-attenuation in both arterial- and portal-dominant phases (n=41, 80% and n=50, 98%), group II showed high-attenuation in the arterial-dominant phase (n=38, 83%) and iso-attenuation in the portal-dominant phase(n=34, 74%), group III showed high-attenuation in the arterial-dominant phase(n=19, 59%) and low-attenuation in the portal-dominant phase(n=17,53%), and group IV showed mixed-attenuation in both arterial- and portal-dominant phases(n=30, 60% and n=26, 52%). CONCLUSION: Hepatocellular carcinomas showed variable enhancing patterns on two-phase spiral CT according to thesize of tumors, and this reflected their hemodynamic characteristics.

Fixed Vocal Cord in Laryngeal Cancers: Mechanisms and Spiral CT Findings

PURPOSE: To analyze the causes of vocal cord fixation in laryngeal cancer and to demonstrate its spiral CT findings. MATERIALS AND METHODS: We retrospectively applied the five pathologic mechanisms of vocal cord fixationto spiral CT findings and evaluated mechanisms of fixed vocal cord in 16 patients with laryngeal cancer of T3 or more on staging. CT findings of another six patients (T2) showing one or more suspicious mechanisms of vocal cord fixation in conventional CT were compared with those of the 16 patients (T3 or more). RESULTS: In 16 patients with laryngeal cancer of T3 or more, the most common finding of vocal cord fixation was the complete replacement of the true vocal cord (including the thyroarytenoid and vocalis muscle) by the tumor and tumor invasion of the paralaryngeal space (n = 16). Other findings were tumor invasion and fixation of the cricoarytenoid joint (n = 9), interference with cord mobility by the bulky mass (n = 6), tumor invasion of the thyroid cartilage, with vocalcord fixation (n = 4) and subglottic tumor spread (n = 3). In another six patients (T2) with suspicious vocal cordfixation, conventional CT showed partial vocal cord invasion and intact or minimal invasion of the paralaryngeal space (n = 3), a bulky mass without vocal cord invasion (n = 1) and subglottic extension but movable vocal cord (n= 2). CONCLUSION: Although the cause of vocal cord fixation from laryngeal cancer may be due to one of five patterns of cancer spread, or to a combination of these, the most common spiral CT finding is complete replacement of true vocal cord by the cancer and tumor invasion of the paralaryngeal space. Accurate evaluation of vocal cord fixation and the extent of the tumor could be evaluated with spiral CT using the breathing technique.

Contrast Enhancement Patterns of Hepatic Masses using Three Phase Spiral CT

PURPOSE: To compare the contrast enhancement patterns of hepatocellular carcinomas(HCCs), hemangiomas, and metastases on three-phase images with spiral CT for differential diagnosis. MATERIALS AND METHODS: Three-phasespiral CT scan was performed in 73 patients with hepatic masses. CT scanning was performed with a table speed of 10mm/sec, section thickness of 10mm, and a reconstruction interval of 5mm, 100-150ml of contrast medium was injected intravenously with an automatic injector at a rate of 2-3mL/sec. CT scans were obtained at 30, 70 and 180 seconds after the start of contrast material injection. RESULTS: The enhancement patterns of 136 lesions in 53 patients with HCCs were as follows : 47 lesions(35%) were totally high and 55(40%) were mixed in the early phase ;30 lesions(22%) were mixed and 66(49%) were totally low in the portal phase ; and 105 lesions(78%) were totally low in the delayed phase. In hemangiomas of 23 lesions in 15 patients, 7 lesions(30%) were peripherally high and11(48%) were totally low in the arterial phase ; 4 lesions(17%) were totally high and 12(53%) were peripherally high in the portal phase ; 10 lesions(42%) were totally high and 4(18%) were peripherally high in the deayed phase. In metastatic liver mali gnancies of 42 lesions in 5 patients, 13 lesions(31%) were peripherally high and 22(52%) were totally low in the arterial phase ; 32 lesions(77%) were totally low in the portal phase, and 35(83%)were totally low in the delayed phase. CONCLUSION: Three-phase spiral CT scanning is a useful diagnostic methodin the differential diagnosis of hepatic masses including HCCs, hemangiomas, and hepatic metastases.

Respiratory Dynamic CT: Functional Evaluation of Main Bronchial Stenosis

PURPOSE: To separately evaluate the respiratory function of both lungs separately in patients with unilateralmain bronchial stenosis or obstruction, applying respiratory dynamic CT using the spiral technique. MATERIALS AND METHODS: This study involved five normal subjects and six patients with main bronchial stenosis. Time-continuous scan data at a selected levels during forced vital capacity maneuver were obtained, and static images were retrospectively reconstructed using 0.67 sec. partial scan data per image. Time-density curves for controls and patients were plotted and compared. RESULTS: The highest values of mean attenuation were -697+/-9 H for the leftlung and -684+/-9 H for the right lung of controls, and -697+/-5HU for the healthy lung and -791+/-3H for thediseased lung of the patients. The lowest values were -837+/-2H for the left lung and -842+/-5H for the right lungof contorls, and -847+/-0H for the healthy lung and -858+/-4H for the diseased lung of patients. Mean durations ofexpiration were 1.64+/-.65 seconds for the left lung and 1.58+/-.50 seconds for the right lung of controls, and1.66+/-.60 seconds for the healthy lung and 1.96±.49 seconds for the diseased lung of patients. Time-attenuationcurves for the right and left lung of controls were not significautly different, but except for the lowest value of mean attenuation, these were signficantly different for the healthy and diseased longs of patients. CONCLUSION: Respiratory dynamic CT is an updated technique which permits imaging of the functional status of lung parenchy maduring respiration. It may be useful in the evaluation and quantification of lung function in patients with proximal airway stenosis.

Role of Double-Phase Spiral CT for T Staging of Gastric Cancer: Radiologic-Pathologic Correlation

URPOSE: To evalvate the role of double-phase spiral CT for T staging of gastric cancers with radiologic-pathologic correlation. MATERIALS AND METHODS: Double-phase spiral CT images of 44 patients of gastriccancers proved by pathologic examination were retrospectively evaluated. We retrospectively classified spiral CTimages of gastric cancers ; classification was from S 0 to S 4 and was based on the degree of change in three multilayered patterns shown in normal gastric wall and whether or not tumor cells had invaded perigastric fattissue. Pathologic classification was based on the T staging of TNM classification for gastric cancers, and wethen correlated these results. RESULTS: In group S1, all of three cases(100%) were proved to be T1 and in groupS2, five(45.5%) of 11 cases were T2. Of five cases with S3 CT findings, three(60%) were proved to be T3s andtwo(40%) were T2. Of 22 cases with S4 CT findings, 19(86.4%) were T3p. Overall sensitivity, specificity, and accuracy were 60.3%, 88. 5%, and 86.9%, respectively. In 35 (79.5%) of the total of 44 cases, the lesions were more enhanced on venous than on arterial phase. CONCLUSION: The accuracy of double-phase spiral CT for T staging of gastric cancers was 86.9%, and in contrast to previous results for conventional or dynamic CT, this level of accuracy was thought to be relatively high. In conclusion, double-phase spiral CT images of gastric cancers were helpful in the diagnosis of T staging.

Triple Phase Spiral CT of The Liver: Degree of Liver Parenchymal Enhancement

PURPOSE: To determine the degree and effect of contrast enhancement of the hepatic parenchyma according to different injection rates, amounts and types of contrast materials. MATERIALS AND METHODS: A total of 270 patients were divided into nine groups. Each group received different volumes(120, 130, or 140ml) and was scannedwith different injection rates of 2, 3 or 4 ml/sec. Three kinds of contrast materials(Ultravist 370, Iopamiro 370, Optiray 320) were used. Hepatic enhancement was measured by comparing quantitative regions of interest(ROI) beforeand after bolus injection of contrast material which were evaluated on arterial, portal and delayed phase duringdouble spiral scanning. RESULTS: There was no significant statistical difference in contrast enhancement between the three kinds of contrast materials. In noncirrhotic patients, hepatic enhancement was greatest on portal phase and was greater at a rate of 4ml/sec than 2ml/sec or 3ml/sec on arterial phase. At the same injection rate, thevolume of contrast material was an important factor on portal and delayed phase. In the cirrhotic patients, Child's C showed more delayed peak enhancement than did Child's A. CONCLUSION: The important factors in contrast enhancement were injection rate on arterial phase and volume on portal and delayed phase. The optimal choice mustbe made after considering intrinsic variables ; in addition, our results are helpful for determining enhancement protocol during double spiral CT scanning.

Correlation Between Contrast Enhancement of Portal Vein and Spleen Size in Dual-phase Spiral CT

URPOSE: To evaluate using spiral CT the effect of spleen size on blood flow in the portal venous system andto know the usefulness of this evaluation. MATERIALS AND METHODS: Fifty-one patients without evidence on spiralCT scan of abnormality thought to affect portal venous flow presented between December 1994 and June 1995. We measured spleen size and Hounsfield units of portal vein in dual-phase, and calculated the ratio of the unit inthe portal phase to that in the arterial phase. Spleen size was measured, using the length of X-axis by that of Z-axis on spiral CT scan. We then measured the correlation between the two values. CT was performed with a Somatom Plus-S scanner(Siemens, Erlangen, Germany). A total dose of 120ml of non-ionic contrast material(Ultravist) was administered at a rate of 3ml/sec. Arterial and portal phase were obtained after 30 seconds and 60 seconds fromthe beginning of the contrast agent injection. RESULTS: The correlation between spleen size and contrast enhancement of the portal vein was relatively significant(Pearson's correlation coefficient(r)=0.41801). CONCLUSIONS: Spleen size significantly affects portal venous flow on spiral CT scan. The evaluation of spleensize and contrast enhancement of the portal vein could be useful in the differential diagnosis of diseases which affect portal venous flow.

Detection and Localization of Islet Cell Tumor of the Pancreas: Usefulness of the Arterial Dominant Phase Images of Spiral CT

PURPOSE: To evaluate the usefulness of the arterial dominant phase images of spiral CT in the detection and localization of pancreatic islet cell tumor. MATERIALS AND METHODS: Six patients with pathologically proven isletcell tumors of the pancreas were studied with two-phase spiral CT. Images of the arterial dominant phase and delayed phase were obtained at 30 and 180 seconds after the initiation of injection of 100 ml of contrast materialat a rate of 3ml/sec. The parameters of scanning were 3-mm thickness, table speed of 4mm/sec, and reconstruction at 2-mm intervals. Images were prospectively analyzed and the operative findings were used as the reference standard for tumor detection and localization. RESULTS: On arterial dominant phase images, lesions were definitely depicted in five patients(83%) and were suspicious in one (17%). In the delayed phase, only two tumors(33%) were demonstrated. CONCLUSION: The arterial dominant phase of spiral CT is useful in the preoperative detection and localization of islet cell tumor of the pancreas.

Pattern analysis of Hemodynamic Changes of the Liver on Combined CT Hepatic Arteriography and CT Arterial Portography

PURPOSE: To evaluate the patterns of hemodynamic changes caused by various pathologic liver conditions. MATERIALS & METHODS: Combined CT hepatic arteriography(CTHA) and CT arterial portography(CTAP), performed in 185 consecutive patients, including 150 with hepatocellular carcinoma, were retrospectively analysed. Of these patients, 48 showed various patterns of hemodynamic change. such change caused by occlusion, stenosis and/or cavernous transformation of the portal vein, by occlusion or stenosis of the hepatic artery, or by the presence of arterioportal(AP) shunt could be classified as follows : type 1, decreased or absent portal flow ; type 2,decreased or absent hepatic arterial flow ; type 3, AP shunt without portal tumor thrombus(PTT) ; and type 4, PTT with transvasal AP shunt, including the presence of cavernous transformation of the portal vein. RESULTS: Type I (n=20) showed hyperattenuation of both PTT and absent portal flow area on CTHA, and reciprocally consistent hypoattenuation on CTAP. Type II (n=6) showed a hypoattenuating area on CTHA, and isoattenuation or slightly hyperattenuation on CTAP. Type III (n=9) showed an oval or wedge-shaped hyperattenuating area on CTHA, anddefective perfusion at the same area on CTAP. In Type IV (n=13), both CTHA and CTAP showed variable findings, according to the amount of transvasal AP shunt, the location and extent of PTT, and/or cavernous transformation ofthe portal vein. CONCLUSION: Pattern analyses of hemodynamic changes on both CTHA and CTAP are helpful inclarifying the primary causes of hemodynamic changes in the liver.