Feasibility of Saline Infusion on the Liver Surface during Radiofrequency Ablation of Subcapsular Hepatic Tumor: An Experimental Study

PURPOSE: The purpose of the study was to evaluate the feasibility of infusion of normal saline onto the surface of the liver capsule for minimizing thermal injury of the adjacent organs during radiofrequency ablation of subcapsular hepatic tumor in an ex-vivo porcine model. MATERIALS AND METHODS: We used porcine small bowel with it's serosal surface spread onto the porcine liver as an experiment model. The puncturing electrode was inserted into a 6 Fr introducer sheath, and the introducer sheath was connected to the infusion pump for creating a saline flow over the liver surface . A total of 15 ablations were divided into the control group (n=5), intermittent saline infusion group (n=5) and continuous saline infusion (n=5) group. The ablations were done during 3 minutes, and the infusion was set at 2 ml/min and stopped every 30 seconds in the intermittent saline infusion group. After the ablation, we measured the size of the ablated lesion on the surface of bowel and liver, and we also measured the depth of hepatic lesion. RESULTS: Ablated areas of bowel and liver surface in the control group, intermittent saline infusion group and continuous infusion group were 210.7+/-89.1 mm2, 74.6+/-27.2 mm2 and 35.8+/-43.4 mm2, respectively, and 312.6+/-73.6 mm2, 228.4+/-110.5 mm2, and 80.9+/-55.1 mm2, respectively. In contrast to the broad base of the ablated area on the surface of the liver in the control group, the shapes of the lesions became narrower approaching to the liver surface in all cases of the continuous saline infusion group, and the shapes of the lesions were broad based in 3 cases and narrow based in 2 cases of the intermittent saline infusion group. CONCLUSION: Continuous infusion of normal saline onto the surface of the liver during radiofrequency ablation of subcapsular hepatic tumor is a feasible method for minimizing thermal injury of the adjacent organs. Further exploration of the optimal parameters or techniques to maximize the hepatic ablation and simultaneously to minimize the thermal injury of adjacent organs is required.

An Experimental Study of Simultaneous Ablation with Dual Probes in Radiofrequency Thermal Ablation

PURPOSE: To determine the differences between sequential ablation with a single probe and simultaneous ablation with dual probes. MATERIALS AND METHODS : Using two 14-gauge expandable probes (nine internal prongs with 4-cm deployment), radiofrequency was applied sequentially (n=8) or simultaneously (n=8) to ten ex-vivo cow livers. Before starting ablation, two RF probes with an inter-probe space of 2 cm (n=8) or 3 cm (n=8) were inserted. In the sequential group, switching the connecting cable to an RF generator permitted ablation with the second probe just after ablation with the first probe had finished. In the simultaneous group, single ablation was performed only after connecting the shafts of both RF probes using a connection device. Each ablation lasted 7 minutes at a target temperature of 105-110 degrees C. The size and shape of the ablated area, and total ablation time were then compared between the two groups. RESULTS: With 2-cm spacing, the group, mean length and overlapping width of ablated lesions were, respectively, 5.20 and 5.05 cm in the sequential group (n=4), and 5.81 and 5.65 cm in the simultaneous group (n=4). With 3-cm spacing, the corresponding figures were 4.99 and 5.60 cm in the sequential group (n=4), and 6.04 and 6.78 cm in the simultaneous group (n=4). With 2-cm spacing, the mean depth of the proximal waist was 0.58 cm in the sequential (group and 0.28 cm in the simultaneous group, while with 3-cm spacing, the corresponding figures were 1.65 and 1.48 cm. In neither group was there a distal waist. Mean total ablation time was 23.4 minutes in the sequential group and 14 minutes in the simultaneous group. CONCLUSION: In terms of ablation size and ablation time, simultaneous radiofrequency ablation with dual probes is superior to sequential ablation with a single probe. A simultaneous approach will enable an operator to overcome difficulty in probe repositioning during overlapping ablations, resulting in complete ablation with a successful safety margin.

Diagnostic Accuracy and Evaluation of Myocardial Viability by Cardiac Magnetic Resonance Imaging in Acute Myocardial Infarction: A Comparison with Thallium-201 Myocardial SPECT

PURPOSE: To assess the usefulness of cardiac MR imaging (MRI) in the diagnosis of acute myocardial infarction and in the assessment of myocardial viability in comparision with Tl-201 SPECT. MATERIALS AND METHODS: We retrospectively studied 17 patients who complained of chest pain and dyspnea with cardiac MRI . The patients were evaluated for the presence or absence of high signal intensity on T2-weighted image (T2WI), abnormal wall motion on 2D - FIESTA, perfusion defect on Gd-DTPA enhanced T1WI, and delayed myocardial enhancement on 15-minutes delay Gd-DTPA enhanced T1WI. The results were correlated with the images on Tl-201 SPECT, taken at rest and stress, through which reversibility of perfusion defect was assessed. RESULTS: Both cardiac MRI and Tl-201 SPECT proved to be useful methods for diagnosing acute myocardial infarction. In order of decreasing correspondence, T2WI, Tl-201 SPECT, delayed enhancement study, and wall motion images all showed significant statistical correlation with the clinical diagnosis of myocardial infarction. Perfusion MRI, on the other hand, showed no significant statistical difference was found between Tl-201 SPECT and cardiac MRI. The results on T2WI showed high accordance with those on Tl-201 SPECT, while delayed myocardial enhancement and wall motion studies showed no agreement with Tl-201 SPECT. CONCLUSION: Cardiac MRI is useful method for diagnosis of acute myocardiac infarction. With respect to the assessment of myocardial viability, the results obtained on cardiac MRI showed high agreement with those on Tl-201 SPECT. However, further study is necessary at this point for standardization and establishment of the methods for assessing myocardial viability on cardiac MRI.

CT Spectrum of Transient Peritumoral Hyperemia after Radiofrequency Thermal Ablation of Hepatic Tumors

PURPOSE: To determine the incidence and pattern of peritumoral hyperemia at CT after radiofrequency thermal ablation of hepatic tumors, as well as its correlation with local marginal recurrence. MATERIALS AND METHODS: Forty-five tumor nodules in 28 patients with hepatocellular carcinoma (n=34) or metastasis (n=11) were treated by RF thermal ablation. Serial follow-up contrast- enhanced CT scans were reviewed by three radiologists for 1) the presence, 2) the morphological characteristics [circumferential, THAD (transient hepatic attenuation difference), nodular form], and 3) the temporal course (acute, persistent, delayed onset pattern) of peritumoral hyperemia after RF thermal ablation. These findings were correlated with the frequency of recurrence at the margin of the treated tumors. RESULTS: The frequency of acute hyperemia observed on immediate follow-up CT scans after RF ablation was 71% (32/45). There was the local recurrence in nine of 32 tumors (28%) with hyperemia and in one of 13 (8%) without hyperemia (p>0.05). Among 32 tumors, the circumferential form was observed in 22 (69%); the THAD form in eight (25%); and the nodular form in two (6%). Marginal recurrence was noted in five of 22 tumors circumferential tumors (23%), in three of eight (38%) with the THAD form, and in one of two (50%) which were nodular. Among 32 nodules, an acute transient pattern was noted in 21 (66%), a persistent pattern in nine (28%), and a nodular pattern in two (6%). There was marginal recurrence in two (10%) of 21 tumors with acute transient hyperemia, in six (67%) of nine with persistent hyperemia, and in both tumors with delayed-onset hyperemia. There was significant correlation between the pattern of persistent/delayed-onset hyperemia and marginal tumor recurrence of (p=0.001). CONCLUSION: Although peritumoral hyperemia after RF thermal ablation therapy is a frequent transient finding at follow-up imaging studies, its temporal pattern may help detect early marginal tumor recurrence.

Radiofrequency Thermal Ablation of Metastatic Liver Tumors: Usefulness of Combined Chemotherapy

PURPOSE: To assess the usefulness of radiofrequency (RF) thermal ablation with combined chemotherapy for the treatment of metastatic liver tumors. MATERIALS AND METHODS: A non-randomized, comparative study was performed in 21 patients with metastatic liver tumors. Inclusion criteria were that these should be less than five in number and less than 6 cm in diameter. Two groups were designed for comparison of the local and remote (new intrahepatic or extrahepatic) tumor control rate (Group A: RF alone, n=11; Group B: RF+combined chemotherapy, n=10). There was no significant difference in age, sex, and mass size between the two groups (p>0.05). All ablations were performed percutaneously with a 50W RF generator and 15G-needle electrode (RITA Medical System Inc.) under US guidance. In group B, six cycles of systemic chemotherapy were performed every month immediately after RF ablation. Follow-up CT scans were obtained within 24 hours of ablation and were compared with the findings of pre-ablation CT scanning. If an ablated lesion covered the mass without any residual enhancing foci, this was defined as complete ablation. Three and six months after ablation, local and remote tumor control rates were compared between the two groups (follow up: range 4 -17 (mean, 10.2) months. RESULTS: In group A, the local tumor control rate was 43.8% (7/16) and 31.2% (5/16) at 3 and 6 months follow-up, respectively, while in group B, the corresponding rates were both 75% (15/20). At three months, the difference in this rate between the two groups was not significantly different (p>0.05), but at 6 months there was significant difference (p<0.05). At 6 months follow-up, the remote tumor control rate for Group A and Group B was 27.3% (3/11) and 80.0% (8/10), respectively, reflecting a significant difference between the two groups (p<0.05). CONCLUSION: In patients with metastatic liver tumor, radiofrequency thermal ablation with combined chemotherapy may be superior to RF thermal ablation alone for both local and remote tumor control.

Positional Shifting of HRCT Findings in Patients with Pulmonary Edema

PURPOSE: To assess the value of positional shifting to a gravity-dependent area, as revealed by HRCT, in differ-entiating pulmonary edema (PE) from other conditions. MATERIALS AND METHODS: Sixteen consecutive patients in whom plain radiographs suggested the presence of pulmonary edema but the clinical findings were indefinite underwent HRCT of the lung. For initial scanning they were in the supine position, and then in the prone position. Findings of ground-glass opacity, interlobular septal thickening and peribronchovascular interstitial thickening were analyzed in terms of the presence and degree of shifting to a gravity-dependent area, a grade of high, intermediate or low being assigned. RESULTS: PE was diagnosed in 8 of 16 cases, the remainder being designated as non-pulmonary edema (NPE). Ground-glass opacity was observed in all 16, while the degree of positional shifting was found to be high in ten (PE:NPE=6:4), intermediate in four (PE:NPE=2:2), and low in two (PE:NPE=0:2). There was no significant difference between the two groups (p > 0.05). Interlobular septal thickening was observed in all but two NPE cases; the degree of shifting was high in six (PE:NPE=6:0), intermediate in one (PE), and low in seven (PE:NPE=1:6). Shifting was significantly more prominent in PE than in NPE cases (p<0.05). Peribronchovas-cular interstitial thickening was positive in all PE cases and one NPE case, with no positional shifting. CONCLUSION: Positional shifting of interlobular septal thickening to a gravity-dependent area, as demonstrated by HRCT, is the most specific indicator of pulmonary edema.

Radiofrequency Thermal Ablation of Benign Cystic Lesion:An Experimental Pilot Study in a Porcine Gallbladder Model

PURPOSE: To determine whether radiofrequency thermal ablation can be used to treat benign cystic lesions in a porcine gallbladder model. MATERIALS AND METHODS: This experimental study of radiofrequency thermal ablation involved the use of 15 exvivo porcine gallbladders and 15-G expandable needle electrodes. To investigate optimal temperature parame-ters,three groups of five were designated according to target temperature: Group A: 70 degrees C; Group B: 80 degrees C; Group C: 90 degrees C. After the target temperature was reached, ablation lasted for one minute. Gallbladder width, height and length were measured before and after ablation, and the estimated volume reduction ratios of the three groups were compared. Whether adjacent liver parenchyma around the gallbladder fossa was ablated by heat conducted from hot bile was also determined, and the thickness of the ablated area of the liver was measured. RESULTS: The volume reduction ratio in Group A, B and C was 42.7%, 41.7% and 42.9%, respectively (p>.05). In all 15 cases, gallbladder walls lost their transparency and elasticity at about 70 degrees C. In nine of ten cases in Groups B and C, the hepatic capsule around the gallbladder fossa was retracted at about 80 degrees C. The mean thickness of liver parenchymal damage adjacent to the gallbladder was 5.4 mm in Group B and 9.8 mm in Group C. In Group A livers, only one case showed minimal gradual parenchymal change. Microscopically, all three groups showed complete coagulation necrosis of the wall. CONCLUSION: On the basis of this feasibility study, radiofrequency thermal ablation is potentially suitable for the ultrasound-guided treatment of symptomatic cystic lesions including benign hepatic or renal cyst.

MR Imaging of Soft-Tissue Vascular Lesions: Pathologic Correlation

In the evaluation of vascular lesions, MR can be used to distinguish slow- from high-flow lesions on the basis of the observed spin-echo MR signal characteristics. MR imaging can also represent features of the static tissues of the vascular lesions that are composed of fibrofatty components, as well as thromboses, phleboliths and muscle atrophy. This paper illustrates the MR findings of various vascular lesions, correlating them with the pathologic specimen and emphasizing on the static tissues.

Radiofrequency Thermal Ablation of Malignant Hepatic Tumors: Post-Ablation Syndrome

PURPOSE: To evaluate post-ablation syndrome after radiofrequency thermal ablation of malignant hepatic tumors. MATERIALS AND METHODS: Forty-two patients with primary (n=29) or secondary (n=13) hepatic tumors under-went radiofrequency thermal ablation. A total of 65 nodules ranging in size from 1.1 to 5.0 (mean, 3.1) cm were treated percutaneously using a 50W RF generator with 15G expandable needle electrodes. We retrospec-tively evaluated the spectrum of post-ablation syndrome including pain, fever(> or =38 C degrees), nausea, vomiting, right shoulder pain, and chest discomfort according to frequency, intensity and duration, and the findings were cor-related with tumor location and number of ablations. We also evaluated changes in pre-/post-ablation serum aminotransferase(ALT/AST) and prothrombin time, and correlated these findings with the number of abla-tions. RESULTS: Post-ablation syndrome was noted in 29 of 42 patients (69.0%), and most symptoms improved with conservative treatment. The most important of these were abdominal pain (n=20, 47.6%), fever (n=8, 19.0%), and nausea (n=7, 16.7%), and four of 42 (9.5%) patients complained of severe pain. The abdominal pain lasted from 3 hours to 5.5 days (mean; 20.4 hours), the fever from 6 hours to 5 days (mean; 63.0 hours). and the nau-sea from 1 hour to 4 days (mean; 21.0 hours). Other symptoms were right shoulder pain (n=6, 14.3%), chest discomfort (n=3, 7.1%), and headache (n=3, 7.1%). Seventeen of 20 patients (85%) with abdominal pain had a subcapsular tumor of the liver. There was significant correlation between pain, location of the tumor, and number of ablations. After ablation, ALT/AST was elevated more than two-fold in 52.6%/73.7% of patients, respectively but there was no significant correlation with the number of ablation. CONCLUSION: Post-ablation syndrome is a frequent and tolerable post-procedural process after radiofrequency thermal ablation. The spectrum of this syndrome provides a useful guideline for the post-ablation management.

Esophageal tubular duplication complicated with intraluminal hematoma: a case report

Esophageal tubular duplication is a rare congenital anomaly. We experienced a patient with esophageal tubular duplication who presented with a swallowing difficulty which was aggravated after a gastrofiberscopic examination. Preoperative diagnosis was intramural hematoma of the esophagus due to trauma caused by endoscopy. Surgical specimen revealed that hematoma was located within a duplicated lumen of the esophagus. The radiologic and endoscopic findings are discussed in correlation with its pathology.

Esophageal tubular duplication complicated with intraluminal hematoma: a case report

Esophageal tubular duplication is a rare congenital anomaly. We experienced a patient with esophageal tubular duplication who presented with a swallowing difficulty which was aggravated after a gastrofiberscopic examination. Preoperative diagnosis was intramural hematoma of the esophagus due to trauma caused by endoscopy. Surgical specimen revealed that hematoma was located within a duplicated lumen of the esophagus. The radiologic and endoscopic findings are discussed in correlation with its pathology.

Primary Hepatic leiomyosarcoma: A case Report

Primary hepatic leiomyosarcoma is a rare tumor, most frequently occurring in liver parenchyma. We recentlyencountered an exophytic hepatic leiomyosarcoma ; CT scans indicated an indistinct border, with the parenchyme ofthe liver and parenchymal beaking suggesting a primary hepatic mass. We present an unusual case of primaryleiomyosarcoma which showed exophytic growth.

Peripheral Type of Small Cell Carcinoma of the Lung: CT Findings

PURPOSE: The purpose of this study was to evaluate the CT findings of peripheral small cell carninoma of the lung. MATERIALS AND METHODS: Of 45 patients with pathologically proven small cell carcinoma, with a solitary nodule in the peripheral lung distal to the segmental bronchus were included in this study. We retrospectively reviewed clinical data and CT findings including size, location, margin, enhancement pattern, lymph node enlargement, and metastasis. RESULTS: All ten masses examined had a well-defined margin, while a lobulated margin was seen in seven patients. The mean diameter was 3.8cm (2.5 -7 .0 cm), and the enhancement pattern was homogeneous in three cases and inhomogeneous in seven. Calcification or air-bronchogram was not present, and focal air density was seen in one case. In five patients, only lung mass was present, and lung mass with lymph node enlargement was seen in one patient. Distant metastasis without lymph node enlargement was noted in two patients and another two showed lymph node enlargement and distant metastasis. CONCLUSION: In ten of 45 cases of small cell carcinoma (22.2 %), the location of the nodule indicated that peripheral small cell carcinoma is not rare. The most frequent CT finding is a well-defined, lobulated mass with inhomogeneous enhancement.

Right to Left Shunt as a Collateral Circulation in a Patient with Superior Vena Cava Syndrome: A Case Report

In patients with superior vena cava syndrome, the form of the collateral circulatory system whichcommuni-cates with the inferior vena cava via various systemic veins usually varics. We found an instance ofunusual collateral circulation : direct communication between the systemic and pulmonary vein in a woman withsuperior vena cava syndrome caused by metastatic lymph node enlargement. In this report, we describe the CT andradionuclide venographic findings.

Prognostic Factors in Transcatheter Arterial Chemoembolizationc of Hepatocellular Carcinoma: Analysis of Morethan 3 Year Survivors

PURPOSE: To determine which prognostic factors contribute to long-term survival after transcatheter arterialchemoembolization(TACE) of hepatocellular carcinoma. MATERIALS AND METHODS: In 100 patients who expired withinone year and 84 who survived or have survived for more than 3 years after TACE, prognostic factors wereretrospectively evaluated. TACE was accomplished by hepatic arterial infusion of a suspension of Lipiodol andanticancer drugs(Mitomycin-C and Adriamycin), either alone or followed by gelfoam embolization. Fisher 's exacttest of probability was used to determine which prognostic factors were statistically significant. RESULTS:Statistically significant prognostic factors were as follows: Child classification(p0.05). CONCLUSION: The prognosisof patients with hepatocellular carcinoma treated by TACE was affected favorably by good liver function(Childclassification A), low alphafetoprotein value, nodular or massive-type tumor, patent main and first-order portalvein, and hypervascular tumor.

Treatment of Invasive Pulmonary Aspergillosis by Combined Intravenous and Transthoracic Injection ofAmphotericin B in a Patient with Acute Leukemia

Invasive pulmonary aspergillosis may be a major cause of lethal opportunistic infection in neutropenicpatients. The purpose of this report is to describe a combined treatment modality involving transthoracicinjection of amphotericin B and gelatin solution for persistent mycetoma within the cavity. Mycetoma may interferewith consolidation chemotherapy after intravenous injection of amphotericin B for invasive pulmonary aspergillosisin a patient with acute monocytic leukemia in whom neutropenia developed during remission induction chemotherapy.

Acute Aortic Intramural Hematoma

PURPOSE: To evaluate the radiologic findings of acute intramural hematoma of the aorta, and the clinical follow up thereof. MATERIALS AND METHODS: Among 34 cases confirmed clinically and radiologically as aortic dissection, an analysis was carried out based on 15 cases in which intramural hematoma without false lumen was demonstrated, on initial CT, 12 cases of in which follow up CT was used and five cases involving an aortogram. Elements such as the shape of the thickened aortic wall, ulcer-like intimal defects, and intimal calcification were examined. Changes in these elements were also examined on follow up CT. RESULTS: DeBackey types I and III accounted for one and 14 cases. respectively. Initial precontrast CT demonstrated continuous, crescentic high attenuation areas along the wall of the descending aorta. In postcontrast scans, the crescentic areas were of relatively lower-attenuation and appeared along the aorta wall. Displaced intimal calcifications were seen in nine of fifteen patients. There was no intimal flap on all five aortogram, while aortic wall thickening and atherosclerotic change were demonstrated in four cases and in one case, case, respectively. Focal ulcers were seen in three cases. Ulcer-like intimal defects were demonstrated in a total of eleven cases (eight on CT, two on aortogram, and one on both). In ten of the twelve cases seen on follow up CT, the thickness of the intramural hematoma was seen to be reduced. Among the 15 cases, the operation was performed in two cases, and the remaining 13 received conservative treatment. In ten cases observed for more than twelve months, a recurrence of symptoms did not occur. CONCLUSION: Eccentric aortic wall thickening in patients who complain of acute chest pain is the result of acute aortic dissection with intramural hematoma, or a penetrating atherosclerotic ulcer of the aorta.The latter may be differentiated from the former by the presence of on ulcer-like intimal defect. When both diseases are limited to the descending aorta, conservative treatment may be effective, unless patients experience persistent or recurrent chest pain, or unless intramural hematoma progresses further.

Normal Anatomical Variation of the Intrahepatic Portal Vein in Korean

PURPOSE: To determine the prevalence of variations in the intrahepatic portions of portal veins, as visualized by arterial portograms, and to examine the surgical implications of these findings in Koreans. MATERIALS AND METHODS: Five hundred and nineteen arterial portograms of 519 patients with no evidence of vascular tumor invasion or distortion were retrospectively reviewed. In all patients, the main, right, right anterior, right posterior and left portal vein were visualized. RESULTS: Variations in intrahepatic portal anatomy were found in 102 patients (19.6%) and involved an immediate trifurcation of the main portal vein in 82 (15.8%) a right posterior segment from the main portal vein in ten (1.9%), a right anterior segment from the left portal vein in nine (1.7%) and an absent horizontal portion from the left portal vein in one (0.2%). CONCLUSION: On arterial portogram, variations in the intrahepatic portions of the portal veins are frequently seen. The recognition of such variations is important in the preoperative evaluation of patients with hepatic tumors, since the variations may have implications for tumor resection, for the localization of tumor thrombi and in interventional radiologic procedures involving the portal vein.

Hemoptysis: Comparison of High-resolution CT with Fiberoptic Bronchoscopy

PURPOSE: To compare the precise roles of high-resolution computed tomography (HRCT) and fiberoptic bronchoscopy (FOB) in the evaluation of patients presenting with hemoptysis and to determine the optimal timing for HRCT. MATERIALS AND METHODS: The results of HRCT and FOB were compared in 23 patients (15 men, 8 women) presenting with hemoptysis. Etiologies included bronchietasis (n=4), parenchymal pulmonary tuberculosis (n=4), lung cancer (n=4), endobronchial tuberculosis (n=2), and broncholithiasis (n=2). Hemoptysis was proved to be due to miscellaneous causes in an additional three cases and to be cryptogenic in four. The diagnostic results of FOB performed before and after HRCT were compared as were those of HRCT performed within and after the first 48 hours of active bleeding. RESULTS: FOB and HRCT offered a correct diagnosis in 39% and 65% of cases, respectively (p=0.005). HRCT demonstrated three cases of bronchiectasis and three of parenchymal pulmonary tuberculosis which were beyond the range of a bronchoscope. In two of five cases in which HRCT findings were nonspecific, chondromatous hamartoma and lung cancer were confirmed by FOB. In cases where HRCT was performed prior to FOB, the latter demonstrated the location and diagnosis in 82% and 47% of cases, respectively (p=0.303) ; when HRCT was performed after FOB, HRCT was correct in 67% and 17% of cases, respectively (p=0.178). In none of three cases (0%) in which HRCT was performed during the first 48 hours of active bleeding did the procedure allow a specific diagnosis. In 15 of 20 (75%) cases in which HRCT was performed after the first 48 hours, however, the diagnosis provided by CT was correct. CONCLUSION: The results of this study suggest that in patients presenting with hemoptysis, both HRCT and FOB should be used for evaluation, since they are diagnostically complementary. FOB is more useful for the diagnosis of endobronchial lesion, and HRCT for bronchiectasis and parenchymal pulmonary tuberculosis. If, in cases of hemoptysis, initial diagnosis is attempted within the first 48 hours of active bleeding, FOB should be the initial step, and HRCT images should not be obtained until active bleeding has been shown on plain chest radiograph to have abated. If this initial approach takes place after the first 48 hours of active bleeding, FOB and HRCT are equally suitable.

Inspiratory and Expiratory Pulmonary CT: Change of Bronchial and Accompanying Pulmonary Arterial Diameter During Respiration in Healthy Adult Men

OBJECT: To evaluate changes in the diameter of bronchi and pulmonary arteries during respiration. MATERIALS AND METHODS: The ratio of the diameter of matched inner bronchi and accompanying pulmonary arteries was calculated from full inspiration and expiration HRCT of healthy men. RESULTS: In 106 pairs of matched bronchi and pulmonary arteries, the brohchial-arterial ratios were 0.61+/-0.18(upper lung), 0.72+/-0.21(lower lung), and0.65+/-0.20(total) at full inspiration and 0.51+/-0.32(upper lung), 0.52+/-0.15(lower lung), and 0.51+/-0.26(total) atfull expiration HRCT, denoting a statistically significant increase in bronchial diameter of the entire lung atfull inspiration. The inner diameter of the bronchus was larger than the diameter of the accompanying pulmonary artery by 0.1% at full expiration and 8.5% at full inspiration. CONCLUSION: The result of this study would be helpful in understanding the physiology of the lung during respiration.