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Purpose: To demonstrate the feasibility of foot blood flow measurement by using dynamic volume perfusion computed tomographic (CT) technique with the upslope method in an animal experiment and a human study., Materials and Methods: The human study was approved by the institutional review board, and written informed consent was obtained from all patients. The animal study was approved by the research animal care and use committee. A perfusion CT experiment was first performed by using rabbits. A color-coded perfusion map was reconstructed by using in-house perfusion analysis software based on the upslope method, and the measured blood flow on the map was compared with the reference standard microsphere method by using correlation analysis. A total of 17 perfusion CT sessions were then performed (a) once in five human patients and (b) twice (before and after endovascular revascularization) in six human patients. Perfusion maps of blood flow were reconstructed and analyzed. The Wilcoxon signed rank test was used to prove significant differences in blood flow before and after treatment., Results: The animal experiment demonstrated a strong correlation (R(2) = 0.965) in blood flow between perfusion CT and the microsphere method. Perfusion maps were obtained successfully in 16 human clinical sessions (94%) with the use of 32 mL of contrast medium and an effective radiation dose of 0.31 mSv (k factor for the ankle, 0.0002). The plantar dermis showed the highest blood flow among all anatomic structures of the foot, including muscle, subcutaneous tissue, tendon, and bone. After a successful revascularization procedure, the blood flow of the plantar dermis increased by 153% (P = .031). The interpretations of the color-coded perfusion map correlated well with the clinical and angiographic findings., Conclusion: Perfusion CT could be used to measure foot blood flow in both animals and humans. It can be a useful modality for the diagnosis of peripheral arterial disease by providing quantitative information on foot perfusion status.

Purpose: To assess diagnostic performance and imaging features of gadoxetic acid-enhanced magnetic resonance (MR) imaging in small (≤1-cm) hepatocellular carcinoma (HCC) detection in patients with chronic liver disease., Materials and Methods: The institutional review board approved this retrospective study and waived informed consent. Sixty patients (56 men, four women; mean age, 60.1 years) with HCC (146 lesions; 70 > 1 cm, 76 ≤ 1 cm) underwent gadoxetic acid-enhanced MR imaging. HCC was confirmed at surgical resection (72 lesions; 30 > 1 cm, 42 ≤ 1 cm) or by showing interval growth with typical enhancement patterns at follow-up dynamic computed tomography or MR imaging (74 lesions; 40 > 1 cm, 34 ≤ 1 cm). Two radiologists assessed MR imaging features and graded likelihood of HCC with a five-point confidence scale. Jackknife alternative free-response receiver operating characteristic (JAFROC) method was used., Results: Mean JAFROC figure of merit for small HCC was 0.717; that for large (>1-cm) HCC was 0.973 with substantial agreement (κ = 0.676). Mean sensitivity and positive predictive value (PPV) were 46.0% (70 of 152) and 48.3% (70 of 145) for small HCC versus 95.0% (133 of 140) and 78.2% (133 of 170) for large HCC, respectively. Eleven of 76 small HCCs (14%) were not seen on MR images, even after careful investigation. MR imaging features of small HCC included arterial enhancement (79%, 60 of 76), hypointensity on hepatobiliary phase (HBP) images (68%, 52 of 76), washout on 3-minute delayed phase images (50%, 38 of 76), hyperintensity on T2-weighted images (43%, 33 of 76), hypointensity on T1-weighted images (32%, 24 of 76), and restriction on diffusion-weighted images (28%, 20 of 72). Arterial enhancement and washout on 3-minute delayed phase images or hypointensity on HBP images occurred in 66% of small HCCs (50 of 76)., Conclusion: Diagnostic performance of gadoxetic acid-enhanced MR imaging for small HCC detection is still low, with mean sensitivity of 46.0% (70 of 152) and mean PPV of 48.3% (70 of 145). By adding hypointensity on HBP images as washout, diagnostic performance for small HCC detection can be improved.

Purpose: To compare the effectiveness of transarterial chemoembolization (TACE), radiofrequency ablation (RFA), and hepatic resection (HR) in patients with small single-nodule hepatocellular carcinoma by using inverse probability weighting to control selection bias., Materials and Methods: This retrospective cohort study was approved by the institutional review board, and the requirement to obtain informed consent was waived. The study included 197 consecutive patients (146 men and 51 women; mean age ± standard deviation, 57.4 years ± 9.7) with single-nodule hepatocellular carcinomas measuring 3 cm or smaller and no vascular invasion who were treated initially with HR (n = 52), RFA (n = 79), or TACE (n = 66) from January 2005 to December 2006 at a single tertiary hospital. The primary endpoint was overall survival., Results: The baseline liver status of the groups differed significantly and was most favorable for the HR group, followed by the RFA group, and then the TACE group. The 5-year overall survival rates were 93.6% in the HR group, 86.6% in the RFA group, and 74.2% in the TACE group (P = .023). However, after inverse probability weighting, weighted survival rates among the three groups were similar (5-year overall survival: 85.6% with HR, 87.6% with RFA, and 80.7% with TACE; P = .834). In multivariate Cox regression analysis, TACE showed a hazard ratio of 0.978 (95% confidence interval: 0.407, 2.347; P = .960) compared with HR and of 1.335 (95% confidence interval: 0.619, 2.879; P = .461) compared with RFA., Conclusion: TACE is an effective treatment that allows achievement of long-term survival rates comparable to those with HR and RFA in patients with small single-nodule hepatocellular carcinoma.

Purpose: To retrospectively compare safety and effectiveness of embolic agents polyvinyl alcohol (PVA) particles versus n-butyl-2-cyanoacrylate (NBCA) for bronchial artery embolization (BAE) for control of hemoptysis., Materials and Methods: Institutional review board approved this retrospective study; informed consent was waived. From January 2005 to December 2008, 406 patients (242 men, 164 women; age range, 6-92 years) with major hemoptysis underwent BAE by using PVA particles (n = 293) or NBCA (n = 113). Technical and clinical success, complications, hemoptysis-free survival rates, and causes of recurrent hemoptysis were compared between PVA and NBCA groups. The differences in hemoptysis-free survival rates were assessed between subgroups stratified to underlying diseases. The predictive factor for recurrent hemoptysis was identified with Cox proportional hazard regression model., Results: Technical success was achieved in 93.9% (275 of 293) and 96.5% (109 of 113) of patients for PVA and NBCA, respectively (P = .463); clinical success was achieved in 92.2% (270 of 293) and 96.5% (109 of 113) of patients for PVA and NBCA, respectively (P = .180). Overall and major complication rates were not statistically different (overall complication rates: 34.1% for PVA, 31.0% for NBCA; P = .56; major complication rates: 0.3% for PVA, 0% for NBCA; P > .999). The 1-, 3-, and 5-year hemoptysis-free survival rates were, respectively, 77%, 68%, and 66% for PVA and 88%, 85%, and 83% for NBCA (P = .01). Recanalization of previously embolized vessels was more frequent in PVA group (21.5%) than in NBCA group (1.8%; P < .001). NBCA group showed hemoptysis-free survival rates superior to PVA group in patients with bronchiectasis (P = .016). PVA (P = .050) and aspergilloma (P < .001) were predictive factors for recurrent hemoptysis., Conclusion: BAE with NBCA provided higher hemoptysis-free survival rates compared with PVA particles without increasing complication rates. This improvement was evident in patients with bronchiectasis and was caused by more durable embolic effect than PVA particles., Supplemental Material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13130046/-/DC1., (RSNA, 2013)

Purpose: To evaluate the diagnostic performance of computed tomographic (CT) enterography in identifying the source of obscure gastrointestinal bleeding and to determine clinical features associated with a higher diagnostic yield of CT enterography., Materials and Methods: The institutional review board approved this study, with waiver of informed consent. CT enterographic images in 65 patients (46 men [mean age, 54 years; range, 18-85 years] and 19 women [mean age, 62.1 years; range, 33-79 years]) who presented with obscure gastrointestinal bleeding between August 2005 and July 2007 were reviewed retrospectively and independently by two radiologists. The diagnostic performance of CT enterography was assessed by using the results of endoscopic and other imaging examinations, surgery, and clinical follow-up as the reference standard. Differences in the diagnostic yield of CT enterography according to patient demographic and clinical features, including age, sex, type and episode of bleeding (occult, initial overt, and recurrent overt), occurrence of recent bleeding, and history of massive bleeding, were evaluated by using univariate and multivariate logistic regression analyses., Results: CT enterography helped identify the source of obscure gastrointestinal bleeding in 16 (24.6%) of 65 patients. The sensitivity, specificity, positive predictive value, and negative predictive value of CT enterography were 55.2% (16 of 29), 100% (32 of 32), 100% (16 of 16), and 71.1% (32 of 45), respectively. Among patients' clinical features, a history of massive bleeding (diagnostic yield, 58.3% [seven of 12]; adjusted odds ratio, 7.2; P = .01) was independently associated with a higher diagnostic yield for CT enterography., Conclusion: CT enterography has a potential role in the evaluation of obscure gastrointestinal bleeding. Despite the limited sensitivity of CT enterography, positive CT enterographic findings can reliably indicate the true source of obscure gastrointestinal bleeding. CT enterography is particularly effective in helping identify the source of bleeding in patients with a history of massive bleeding., Supplemental Material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101936/-/DC1., (RSNA, 2011)

Purpose: To determine the efficacy and safety of transarterial chemoembolization (TACE) in patients with hepatocellular carcinoma (HCC) and main portal vein (MPV) invasion., Materials and Methods: This study was approved by the institutional review board, and the requirement to obtain informed consent was waived. The authors retrospectively assessed the electronic medical records of patients in whom HCC with MPV invasion was newly diagnosed from January 2004 to December 2007 at a single tertiary medical center. Patients with decompensated hepatic function were excluded. Outcomes of patients treated with TACE were compared with those of patients given supportive care according to Child-Pugh class., Results: One hundred twenty-five patients (104 men and 21 women; mean age, 55.7 years; age range, 33.4-83.0 years) were included. The median overall survival was 3.7 months (range, 0.2-33.3 months). Eighty-three of the 125 patients (66.4%) were treated with TACE and 42 (33.6%) received supportive care. Repeated TACE showed significant survival benefits compared with supportive care in patients with Child-Pugh class A (median survival, 7.4 months vs 2.6 months, respectively; P < .001) and class B (median survival, 2.8 months vs 1.9 months, respectively; P = .002) disease. Results of multivariate analysis showed that treatment with TACE (hazard ratio, 0.263; 95% confidence interval [CI]: 0.164, 0.424; P < .001) and Child-Pugh class A status (hazard ratio, 0.550; 95% CI: 0.368, 0.822; P = .004) were independent predictive factors of a favorable outcome. There were no procedure-related deaths within 4 weeks after TACE, and patient morbidity was 28.9% (24 of 83 patients)., Conclusion: TACE can be performed safely and may improve the overall survival of patients with HCC and MPV invasion., (© RSNA, 2011.)

Purpose: To analyze the clinical outcomes of chemoembolization for solitary caudate lobe hepatocellular carcinoma (HCC) found at initial presentation., Materials and Methods: This retrospective study was approved by the institutional review board; the requirement for informed patient consent was waived. From July 1998 to June 2009, 40 patients (28 men, 12 women; mean age, 57 years) found to have a single HCC lesion in the caudate lobe at initial presentation were treated with chemoembolization and evaluated for overall survival and progression-free survival. Multivariate analyses for potential clinical and radiologic factors were performed by using the Cox proportional hazard model., Results: Selective chemoembolization via the caudate artery was achieved in 34 (85%) patients. Overall survival rates at 1, 2, 3, 4, and 5 years were 92%, 79%, 65%, 56%, and 56%, respectively. Selective chemoembolization of the caudate artery was a critically important factor in longer overall survival (hazard ratio, 0.091; 95% confidence interval [CI]: 0.021, 0.389; P < .001), and portal vein tumor thrombosis (hazard ratio, 31.25; 95% CI: 4.88, 200.1; P < .001) and multiple tumor-feeding vessels (hazard ratio, 6.87; 95% CI: 1.47, 32.1; P = .014) were significant factors in shorter overall survival. Selective chemoembolization of the caudate artery was also a significant factor in longer progression-free survival (hazard ratio, 0.278; 95% CI: 0.10, 0.76; P = .013)., Conclusion: Selective chemoembolization via the caudate artery is possible in most patients with caudate lobe HCC and a critical factor in longer overall survival and longer progression-free survival.

Purpose: To identify and evaluate the spectrum and prevalence of celiac axis (CA) and common hepatic artery (CHA) variations by using spiral computed tomography (CT) and digital subtraction angiography (DSA)., Materials and Methods: Institutional review board approval was obtained, and the requirement for informed patient consent was waived. The findings in 5002 patients who underwent spiral CT and DSA were retrospectively evaluated. CHA was defined as an arterial trunk containing at least one segmental hepatic artery and the gastroduodenal artery. The pattern of the aortic origin of the branches of the CA and superior mesenteric arteries was analyzed. The CHA anatomy was then investigated., Results: Of 15 possible types of CA variation, 13 types were identified. A normal CA was noted in 4457 (89.1%) of the 5002 patients. Twelve types of CA variation were identified in 482 (9.64%) patients. In the remaining 63 (1.26%) patients, the CA anatomy was classified as ambiguous because the CHA was absent owing to separate origins of the hepatic arteries and the gastroduodenal artery (n = 55) or because the origin of the CHA could not be determined owing to persistent anastomotic channels (n = 8). Seven CHAs originating from the normal CA had a retroportal (n = 6) or transpancreatic (n = 1) course. All eight CHAs originating from the left gastric artery passed the fissure of the ligamentum venosum. The 148 CHAs originating from the superior mesenteric artery showed diverse relationships with the pancreas--being supra-, trans-, or infrapancreatic--and the superior mesenteric-portal venous axis--being pre- or retroportal. The 20 CHAs originating from the aorta had a normal suprapancreatic preportal course., Conclusion: Known or newly found CA and CHA variations could be systematically described in detail. The authors propose a hypothetical anatomic model for summarizing the observed CHA variations., (RSNA, 2010)

Purpose: To prospectively compare the accuracy of computed tomographic (CT) and magnetic resonance (MR) enterography and small-bowel follow-through (SBFT) examination for detection of active small-bowel inflammation and extraenteric complications in patients with Crohn disease (CD)., Materials and Methods: The institutional review board approved the study protocol; informed consent was obtained from all participants. Thirty-one consecutive patients who had CD or who were suspected of having CD underwent CT and MR enterography, SBFT, and ileocolonoscopy. Two independent readers reviewed CT and MR enterographic and SBFT images for presence of active terminal ileitis and extraenteric complications. Accuracy values of CT and MR enterography and SBFT for identification of active terminal ileitis were evaluated with the receiver operating characteristic method, with ileocolonoscopic findings as the reference standard. Sensitivity values of CT and MR enterography and SBFT for detection of extraenteric complications were compared by using the McNemar test, with results of imaging studies, surgery, and physical examination as reference standards., Results: The study population included 30 patients (17 men, 13 women; mean age, 29.0 years) with CD. Differences in areas under the receiver operating characteristic curves for CT enterography (0.900 and 0.894), MR enterography (0.933 and 0.950), and SBFT (0.883 and 0.928) for readers 1 and 2, respectively, in the detection of active terminal ileitis were not significant (P > .017). Sensitivity values for detection of extraenteric complications were significantly higher for CT and MR enterography (100% for both) than they were for SBFT (32% for reader 1 and 37% for reader 2) (P < .001)., Conclusion: Because MR enterography has a diagnostic effectiveness comparable to that of CT enterography, this technique has potential to be used as a radiation-free alternative for evaluation of patients with CD.

Purpose: To retrospectively evaluate the vascular anatomy of the internal mammary arteries that supply hepatocellular carcinomas (HCCs), with an emphasis on number of tumor feeders., Materials and Methods: This retrospective study was approved by the institutional review board; informed consent was waived. Between August 1996 and July 2005, internal mammary arteries that supply HCCs were found in 97 (2.2%) of 4438 patients (76 men, 21 women; mean age, 55 years +/- 10.5 [standard deviation]; range, 19-79 years). Computed tomographic scans and digital subtraction angiograms in these 97 patients were retrospectively reviewed in consensus by two interventional radiologists. Tumor size, number of tumor feeders, and tumor location were recorded. The t test and analysis of variance were used to correlate tumor size with number of tumor feeders, tumor feeder laterality, and transcatheter arterial chemoembolization (TACE) time., Results: The following 125 tumor feeders were identified in 97 patients: phrenic branch (n = 59), musculophrenic artery (n = 40), superior epigastric artery (n = 15), anterior intercostal artery (n = 6), ensiform artery (n = 4), and pericardiacophrenic artery (n = 1). In two patients, tumors were in dorsal hepatic areas directly beneath the diaphragm. Half of the tumors located in liver segments II or III were supplied by the right internal mammary artery. In three patients, the tumor feeders from the left internal mammary artery crossed the midline. Tumor size was not statistically associated with number of tumor feeders (P = .076), tumor feeder laterality (P = .141), and TACE time (P = .729)., Conclusion: The common tumor feeders of the internal mammary artery are the phrenic branch and the musculophrenic artery. Moreover, the internal mammary artery can supply a tumor even in the dorsal hepatic area.

Purpose: To evaluate the feasibility of an iodized oil emulsion that is used for the chemoembolization of hepatocellular carcinoma as a modifier of a nonviral gene transfer system for intraarterial gene delivery in experimentally induced hepatic tumors., Materials and Methods: Experiments were performed in accordance with National Institutes of Health guidelines for the care and use of laboratory animals and were approved by the animal research committee at Seoul National University Hospital. VX2 carcinoma was implanted into the liver of 26 rabbits. Four nonviral gene transfer systems were prepared by using pCMV-luc+ as a reporter gene. The first system consisted of a DNA and polyethylenimine (PEI) complex (n = 7); the second, of a DNA and PEI complex mixed with iopamidol and iodized oil (n = 7); the third, of a DNA and PEI complex mixed with iopamidol (n = 7); and the fourth, of a DNA and PEI complex mixed with iodized oil (n = 5). For the DNA and PEI complex that was mixed with iopamidol and iodized oil, iopamidol was used to stabilize the emulsion. Twenty days after tumor implantation, intraarterial gene delivery was performed by selective catheterization of the hepatic artery. Rabbits were euthanized 24 hours after gene delivery. Luciferase activity was assayed in the tumor, left hepatic lobe, right hepatic lobe, and other organs and was statistically analyzed for comparison between complexes by using the Kruskal-Wallis test., Results: Luciferase activity in the tumor was significantly higher for the group that received DNA, PEI, iopamidol, and iodized oil than for any other group (Kruskal-Wallis test, P < .05). Luciferase activity in the left hepatic lobe, right hepatic lobe, and other organs was not significantly different between complexes. Selective gene expression in tumor cells was confirmed by means of immunohistochemical analysis for luciferase., Conclusion: It is feasible to use an iodized oil emulsion system for the intratumoral transfection of nonviral vectors in experimentally induced hypervascular hepatic tumors., ((c) RSNA, 2006.)

Purpose: To evaluate the antitumor effects of transcatheter arterial chemoembolization (TACE) with a solution of an anticancer drug (Paclitaxel; Bristol-Myers Squibb, Princeton, NJ) and iodized oil (Lipiodol; Laboratoire Gurerbet, Aulnay-Sous-Bois, France) (hereafter, the solution), as well as intratumor concentration and hepatotoxicity, in experimentally induced liver tumor., Materials and Methods: VX2 carcinoma was grown in livers of 30 rabbits. In 18 rabbits, TACE was performed with the high-dose solution (4 mg anticancer drug and 0.4 mL iodized oil, n = 6), the low-dose solution (1 mg anticancer drug and 0.4 mL iodized oil, n = 6), or iodized oil alone (0.4 mL, n = 6) in a control group. One week later, the growth ratio and residual viable proportion of the tumors were calculated on the basis of findings at spiral computed tomography and histopathologic examination. Hepatic and hematologic toxicities were evaluated by means of biochemical analysis. Differences between the three groups were statistically assessed with the Kruskal-Wallace and Mann-Whitney U tests. The remaining 12 animals were treated with the high-dose solution and serially sacrificed for clarification of chronologic change of concentration of the anticancer drug in liver tissues., Results: Growth ratios and residual viable proportions of the tumors were significantly lower in the solution groups (high dose, 3.3% +/- 6.2 [mean +/- SD] and 2.8% +/- 3.6, respectively; low dose, 18.7% +/- 7.4 and 12.7% +/- 6.1, respectively) than in the control group (68.3% +/- 12.7 and 31.1% +/- 8.8, respectively) (P <.05). Hepatotoxicity was transient in all but one rabbit, which died 2 days after TACE with substantial biochemical changes. The anticancer drug accumulated in tumor where the concentration peaked at day 3 and returned to levels comparable to those for normal hepatic parenchyma at 7 days after TACE., Conclusion: TACE with the Paclitaxel-Lipiodol solution has dose-dependent antitumor effects without major toxicities in VX2 liver tumor., (Copyright RSNA, 2003)

Purpose: To evaluate the additional diagnostic value of unenhanced computed tomographic (CT) images in the depiction of viable tumor in patients who were treated with transcatheter arterial chemoembolization (TACE) for hepatocellular carcinoma (HCC) and followed up with biphasic helical CT that included the acquisition of unenhanced images., Materials and Methods: We performed helical CT (with unenhanced, arterial, and portal phases) in 54 patients who had been treated with TACE for HCC. Image analysis was first performed with only those images obtained in the arterial and portal venous phases of helical CT. A second analysis was then performed with unenhanced images, arterial images, and portal venous images that focused on the additional value of unenhanced images. The value of additional unenhanced images was evaluated by means of interobserver agreement (kappa statistic) and receiver operating characteristic (ROC) analysis., Results: The two readers detected 128 and 129 lesions. Unenhanced images were valuable for 32 of 129 lesions (23 patients) for reader 1 and for 29 of 128 lesions (21 patients) for reader 2. Although there was no significant difference between biphasic CT alone and biphasic CT with unenhanced images, results of ROC analysis showed higher diagnostic performance with biphasic CT with unenhanced images than with biphasic CT alone for detecting viable tumor., Conclusion: The study data demonstrate the diagnostic value of unenhanced images interpreted in conjunction with biphasic CT images for follow-up of patients who have previously been treated with TACE for HCC.

Purpose: To assess the application of stent-grafts in the management of aortic and arterial aneurysms in patients with Behçet disease., Materials and Methods: Nine aneurysms in seven patients were managed with various types of stent-grafts. Diagnoses were based on clinical findings. The aortic aneurysms (n = 3) were thoracic (n = 1), suprarenal (n = 1), or infrarenal (n = 1). The arterial aneurysms (n = 6) were in the right and left subclavian (n = 2), right common carotid (n = 2), right brachiocephalic (n = 1), or left common iliac arteries (n = 1). A tandem connection of Gianturco stent covered with polytetrafluorethylene was placed in three aneurysms, and a balloon-expandable stent was placed in six., Results: The stent-graft was successfully placed in all patients. Immediate follow-up angiography revealed complete exclusion of the aneurysm in all cases. Follow-up computed tomography performed 3 days to 2 weeks later revealed complete exclusion and thrombosis of the aneurysm and patency of the stent-graft in six patients. In one patient, total occlusion of the artery with a stent occurred due to flow disturbance caused by double lesions. During follow-up (range, 6-59 months; mean, 28 months), the aneurysm resolved and completely regressed in four patients. A recurrent aneurysm at the distal margin of previously inserted stent-graft was successfully managed with an additional stent-graft., Conclusion: The findings in this initial experience suggest that stent-graft insertion may be a safe and effective alternative to surgical treatment of aortic and arterial aneurysms in patients with Behçet disease.

Purpose: To discover and evaluate the effective treatment methods to prevent or relieve true-lumen collapse in models of aortic dissection., Materials and Methods: Two phantoms were built to simulate type B aortic dissection. After true-lumen collapse was induced, experiments were conducted to evaluate the effectiveness of clinically relevant variables in relieving the collapse. Variables included entry-tear size, branch-vessel flow distribution, distal reentry communication between the true and false limbs, aortic fenestrations, and pump output. To test the effect of closing the entry tear, a stent-graft was deployed over the entry tear under physiologic conditions in a mock-flow loop. The difference in the effect of each variable on the prevention and relief of true-lumen collapse was also investigated., Results: It was more difficult to relieve true-lumen collapse than it was to prevent it. Placement of a stent-graft over the entry tear was the most effective method of relieving true-lumen collapse. Less-effective procedures included opening a false-lumen outflow branch and opening the distal reentry branch. Opening the fenestration-branch loops, meant to simulate the creation of artificial fenestrations in the intimal flap, did not relieve true-lumen collapse., Conclusion: The definitive treatment for true-lumen collapse in aortic dissection is direct repair of the entry tear to decrease false-lumen inflow. Otherwise, increasing the false-lumen outflow and/or creating distal fenestrations between the true and false lumina distal to the level of the compromised aortic branch are less-effective alternatives.

Purpose: To investigate the causative factors in true-lumen collapse in a model of aortic dissection., Materials and Methods: Phantoms with an aortic arch, true and false lumina with abdominal branch vessels, and a distal bifurcation were used to model a Stanford type B aortic dissection. The effects of anatomic factors (entry-tear size, branch-vessel flow distribution, fenestrations, distal reentry communication) and physiologic factors (peripheral resistance in the branch vessels, pump output and rate, vascular compliance) on true-lumen collapse were investigated. The morphology of the true lumen was observed. Branch pressures and flow rates were measured., Results: True-lumen collapse was induced and was exacerbated by an increase in the size of the entry tear, a decrease in the false-lumen outflow caused by occluding the false-lumen branch vessels, and an increase in the true-lumen outflow caused by lowering the peripheral resistance in true-lumen branch vessels. Two kinds of true-lumen collapse depended on pump output. With low pump output and low outflow resistance from the true lumen, the true lumen collapsed. With high pump output and low inflow resistance in the false lumen, the true lumen was compressed. Distal reentry communication between the true and false limbs was more effective than aortic fenestrations in preventing true-lumen collapse., Conclusion: True-lumen collapse in this dissection model strongly depends on the difference in the ratios of inflow capacity to outflow capacity in the true and false lumina. Both anatomic and physiologic factors can affect true-lumen collapse.

Purpose: To determine the two-phase (hepatic arterial phase [HAP] and portal venous phase [PVP]) spiral computed tomographic (CT) findings of a nontumorous arterioportal shunt in the cirrhotic liver that can mimic a hypervascular tumor., Materials and Methods: For 14 months, 803 patients with known or suspected hepatocellular carcinoma were referred for initial or repeated transcatheter arterial chemoembolization (TACE). Twenty-nine hyperattenuating lesions on HAP CT images obtained in 25 patients (23 men, two women; age range, 39-70 years) were regarded as nontumorous arterioportal shunts and were included in this study. The diagnosis of nontumorous arterioportal shunt was established by four radiologists who reviewed the two-phase spiral CT images and hepatic angiograms., Results: The longest dimension of the lesion was 1.0-7.9 cm (mean dimension, 2.9 cm). The morphology at HAP CT was wedge-shaped in 25 (86%), geographic (ie, focal area with irregular outline) in two (7%), and nodular in two (7%) lesions. All lesions were homogeneous in attenuation. Hyperattenuating linear branching structures that represented early opacification of portal veins were demonstrated during the HAP in nine (31%) lesions. PVP CT images showed these lesions as isoattenuating (n = 20 [69%]) or slightly hyperattenuating (n = 9 [31%]). Iodized oil CT images showed faint or no accumulation of iodized oil in all lesions., Conclusion: In cirrhotic liver, nontumorous arterioportal shunts can be a cause of pseudolesions that mimic hypervascular tumors at two-phase spiral CT. Lesions that have the typical wedge-shaped and homogeneous appearance with or without internal linear branching structures during the HAP and that are isoattenuating or slightly hyperattenuating during the PVP can suggest this unusual condition.

Purpose: To compare power and conventional color Doppler sonography in the depiction of the intratumoral vasculature of hemangiomas, hepatocellular carcinomas (HCCs), and metastases of the liver., Materials and Methods: Thirty-two patients with liver tumors (12 hemangiomas, 11 HCCs, and nine metastases) were prospectively evaluated with power and conventional color Doppler sonography by using a 2-4-MHz convex probe with 2-MHz Doppler frequency. Power Doppler sonography was performed with a 75%-88% gain. Conventional color Doppler sonography was performed with a 55%-75% gain and a pulse repetition frequency of 700 Hz. Power Doppler signals and color Doppler signals interrogated in one plane were analyzed by two radiologists, who subjectively rated power Doppler sonography as superior, equal, or inferior to color Doppler sonography., Results: Overall, power Doppler sonography was superior to color Doppler sonography in 18 patients and equal in 14 (P < .01). In hemangiomas, power Doppler sonography was superior to color Doppler sonography in 10 patients and equal in two (P < .01). In HCCs, power Doppler sonography was superior to color Doppler sonography in four patients and equal in seven (P > .05). In metastases, power Doppler sonography was superior to color Doppler sonography in four patients and equal in five (P < .05)., Conclusion: Power Doppler sonography is more sensitive than color Doppler sonography in the depiction of the vasculature of liver tumors, particularly in hemangiomas.

Purpose: To assess diagnosis of the nutcracker (renal vein entrapment) syndrome with Doppler ultrasonography (US)., Materials and Methods: Doppler US findings in 16 patients with the nutcracker syndrome and in 18 healthy control subjects were compared. The anteroposterior (AP) diameter and peak velocity (PV) were measured at the hilar portion of the left renal vein (LRV) and at the LRV between the aorta and the superior mesenteric artery., Results: The mean AP diameters of the LRV were 10.0 mm +/- 2.0 (standard deviation) and 1.9 mm +/- 1.0 (ratio, 5.0 +/- 2.3) in the patient group and 7.2 mm +/- 1.8 and 2.3 mm +/- 0.6 (ratio, 3.3 +/- 1.1) in the control group. The PVs at the two locations were 14.2 cm/sec +/- 2.5 and 110.7 cm/sec +/- 35.8 (ratio, 7.9 +/- 2.7) in the patient group and 18.6 cm/sec +/- 3.7 and 50.9 cm/sec +/- 27.9 (ratio, 2.8 +/- 1.5) in the control group. Differences in AP diameter and PV were statistically significant between the two groups (P < .01)., Conclusion: Doppler US of the LRV with measurement of the AP diameter and PV may be useful in diagnosing the nutcracker syndrome.

Purpose: To elucidate major complications and their predisposing factors in transcatheter oily chemoembolization (TOCE) for hepatic tumors., Materials and Methods: In a retrospective study of 351 patients (aged 26-82 years) with hepatic tumors, TOCE was performed 942 times with an emulsion of iodized oil (3-40 mL) and doxorubicin hydrochloride (20-60 mg). In 126 patients, TOCE was followed by absorbable gelatin sponge embolization., Results: Complications were severe postembolization syndrome (n = 53); hepatic insufficiency (n = 20), infarction (n = 1), or abscess (n = 1); intrahepatic biloma formation (n = 3); tumor rupture (n = 3); septicemia (n = 9); coagulopathy (n = 1); gastrointestinal bleeding (n = 10); gallbladder (n = 5) or splenic infarction (n = 4); pulmonary oil embolism (n = 6); and spinal cord injury (n = 1). Important predisposing factors were major portal vein obstruction, compromised hepatic functional reserve, biliary obstruction, previous biliary surgery, excessive amount (> 20 mL) of iodized oil, hepatic arterial occlusion after repeated TOCE, and nonselective embolization., Conclusion: Most patients with major complications after TOCE had preexisting risk factors.

Purpose: To evaluate mural changes in the aorta and pulmonary artery in Takayasu arteritis by using computed tomographic (CT) angiography., Materials and Methods: CT angiography was prospectively performed in 12 women with Takayasu arteritis and in 10 healthy adults. Scanning included three distinct phases: precontrast (before administration of contrast material), arterial, and delayed., Results: Precontrast transverse images revealed a high-attenuation aortic wall (10 patients) and mural calcifications in the aorta (nine patients). Arterial-phase images revealed circumferential wall thickening of 1-4 mm in all patients and enhancement in five patients with active disease. Delayed-phase CT revealed circumferential enhancement in eight patients. A concentric, low-attenuation ring was also identified inside the aorta on the arterial-phase (two patients) and delayed-phase (three patients) images. In the pulmonary artery, wall thickening was revealed with early and delayed enhancement in two patients., Conclusion: CT angiography may demonstrate changes in the vascular wall in patients with Takayasu arteritis.

The medical records of 336 patients with hepatocellular carcinoma who underwent transcatheter oily chemoembolization (TOCE) performed via the hepatic artery were retrospectively reviewed to ascertain the occurrence of symptomatic pulmonary oil embolism. In 14 patients, more than 20 mL of iodized oil was administered. In six of these 14 patients, respiratory symptoms of cough, hemoptysis, and dyspnea developed 2-5 days after TOCE, and their chest radiographs showed diffuse bilateral pulmonary parenchymal infiltrate. Their arterial partial pressure of oxygen while they breathed room air ranged from 39 to 60 mm Hg during maximum hypoxemia. The symptoms, arterial hypoxemia, and chest radiographic abnormalities completely cleared 10-28 days after TOCE in the five patients who survived. One patient died 10 days after TOCE because of respiratory arrest with a progression of pulmonary infiltrate. Although histopathologic proof is lacking, it is concluded that massive pulmonary embolization of iodized oil was the primary cause of the clinical and radiographic manifestations in these six patients.

To assess the capability of magnetic resonance (MR) imaging to define the presence, distribution, and severity of the hypertrophic process, MR imaging was performed in 20 patients with hypertrophic cardiomyopathy and in five healthy volunteers. Among the 20 patients, 13 were classified as having asymmetric septal hypertrophy and seven as having apical hypertrophy. The mean myocardial thickness in the four-chamber view obtained in end diastole in asymmetric septal hypertrophy was 23.5 mm +/- 6.8 (mean +/- standard deviation) in the basal septum; the ratio of septal to posterolateral wall thickness was 2.05 +/- 0.44 (P < .05); those values were 10.4 mm +/- 2.7 and 1.01 +/- 0.19, respectively, in five healthy volunteers. The mean myocardial thickness in apical hypertrophy was 25.3 mm +/- 4.1 in the apex, and the ratio was 2.21 +/- 0.51 (P < .05); these values were 9.6 mm +/- 1.5 and 0.95 +/- 0.17, respectively, in five healthy volunteers. Three different subtypes of hypertrophic cardiomyopathy - resting obstructive (n = 5), latent obstructive (n = 3), and nonobstructive (n = 5) - were classified according to findings at catheterization in the 13 patients with asymmetric septal hypertrophy.