Endovascular repair of abdominal aortic aneurysm: helical CT findings]

Endovascular repair of infrarenal abdominal aortic aneurysms is currently widely diffuse. Imaging plays a major role in the preprocedural patient evaluation, implantation of stent-graft, and patient follow-up. The aim of this paper is to describe the more frequent findings that can be seen in CT examinations after endovascular repair of infrarenal abdominal aortic aneurysm. We discuss CT findings related to the aneurysm (size, exclusion with complete perigraft thrombosis, back-filling of aneurysm sac via branch vessels) and to the device (dislocation, rotation, kinking, device expansion, patency/thrombosis, device disruption). We also show some examples of incorrect assembly of the modular components of the stent-graft.     

Erdheim-Chester病:胸部受累的CT表现

目的回顾性分析40例经过免疫组化和组织学证实的Erdheim-Chester病(ECD)病人,当病变累及胸部时,其纵隔、心血管和胸膜肺的CT表现。方法胸部和心血管影像     

Erdheim-Chester disease: CT findings of thoracic involvement

Objective:  

To retrospectively assess the association of mediastinal, cardiovascular and pleuropulmonary findings on chest CT of 40 patients with immunohistochemically and histologically proven Erdheim-Chester disease (ECD).     

Detection of hypovascular hepatic metastases at triple-phase helical CT: sensitivity of phases and comparison with surgical and histopathologic findings

PURPOSE: To compare the respective sensitivities of unenhanced, arterial-dominant, and portal-dominant phase helical computed tomography (CT) in the preoperative depiction of hypovascular hepatic metastases by using intraoperative ultrasonographic (US) and histopathologic findings as the standard of reference. MATERIALS AND METHODS: In this prospective study, 32 patients with 59 surgically and histopathologically proved hypovascular hepatic metastases underwent triple-phase helical CT of the liver, which included unenhanced, arterial-dominant, and portal-dominant phase scanning. Images from each phase were separately analyzed by three readers, and disagreements were resolved with consensus readings. The findings on CT images were compared with intraoperative US and histopathologic findings on a lesion-by-lesion basis to determine the sensitivity of each imaging phase. Statistical review of the lesion-by-lesion analysis was performed by using the Wilcoxon rank sum test. RESULTS: Among 59 hepatic metastases, unenhanced, arterial-dominant, and portal-dominant phase helical CT imaging depicted 39 (66.1%; 95% CI: 53.3%, 76.8%), 44 (74.5%; 95% CI: 62.2%, 83.9%), and 54 (91.5%; 95% CI: 81.6%, 96.3%) metastases, respectively. Portal-dominant phase imaging depicted significantly more hypovascular hepatic metastases than did unenhanced (P <.001) or arterial-dominant (P <.01) phase imaging (Wilcoxon test). CONCLUSION: Preoperative use of triple-phase helical CT in patients with hypovascular hepatic metastases may not be warranted. Portal-dominant phase helical CT imaging allows depiction of significantly more hypovascular hepatic metastases than does imaging during any of the other phases.     

Descending thoracic aortic aneurysm: thoracic CT findings after endovascular stent-graft placement.

PURPOSE: To evaluate the usefulness of thoracic computed tomography (CT) after placement of an endovascular stent-graft for the treatment of descending thoracic aortic aneurysm. MATERIALS AND METHODS: From 1992 to 1996, 85 patients with thoracic aortic aneurysm underwent stent-graft placement. In 63 patients, thoracic CT scans were obtained both before and within 10 days after placement. The CT findings were retrospectively studied, and their clinical effect analyzed. In 20 of 63 patients, long-term follow-up CT findings were also evaluated. RESULTS: After stent-graft placement in the 63 patients, CT demonstrated an increase in pleural effusion in 46 (73%), periaortic changes in 21 (33%), perigraft leak in 13 (21%), atelectasis in six (10%), mural thrombus within the stent-graft in two (3%), and new aortic dissection in one (2%). The mean maximum diameter of the aneurysm was 58.8 mm before and 60.0 mm after stent-graft insertion. Sixty-two (98%) patients were successfully treated until discharge. Interventional procedures were performed to eliminate the leakage into the aneurysm sac in 10 patients with perigraft flow depicted at CT. Other complications were managed conservatively. CONCLUSION: Thoracic CT is useful in the treatment of patients after stent-graft insertion for the management of descending thoracic aortic aneurysm.     

Evaluation of abdominal aortic aneurysm after endoluminal treatment: comparison of color Doppler sonography with biphasic helical CT

OBJECTIVE: The purpose of this study is to compare color Doppler sonography with biphasic helical CT in the evaluation of abdominal aortic aneurysms after endovascular repair. MATERIALS AND METHODS: Fifty-five patients prospectively underwent both color Doppler sonography and helical CT within 7 days after treatment by endovascular stent-graft. Aneurysmal thrombosis, the patency of the grafts, and the presence of a leak were evaluated in all patients. When a perigraft leak was observed, an attempt was made to identify its origin and outflow vessels. Helical CT was considered the gold standard technique. RESULTS: Helical CT revealed aneurysmal thrombosis in 33 patients and a perigraft leak in 22 patients. In five patients, helical CT detected a small perigraft leak not shown by color Doppler sonography. In three patients with suboptimal examinations, color Doppler sonography revealed a suspected perigraft leak that was not confirmed by helical CT. In these eight patients, the perigraft leak was sealed or no longer observed during follow-up. Compared with enhanced helical CT, the sensitivity and specificity of color Doppler sonography for the diagnosis of a perigraft leak were 77% and 90%, respectively. In seven other patients, helical CT was superior to color Doppler sonography in detecting the origin of the perigraft leak and the outflow vessels. Two iliac artery dissections and one distal migration of the prosthesis were revealed only by helical CT. CONCLUSION: Although color Doppler sonography may detect substantial perigraft leaks, helical CT is superior for detecting the origin of the perigraft leak, the outflow vessels, and the detection of complications related to the procedure.     

Hepatocellular carcinoma in patients with nonalcoholic fatty liver disease: helical CT and MR imaging findings with clinical-pathologic comparison

PURPOSE: To retrospectively evaluate the clinical, pathologic, and helical computed tomographic (CT) and magnetic resonance (MR) imaging findings of hepatocellular carcinoma (HCC) in patients with nonalcoholic fatty liver disease (NAFLD). MATERIALS AND METHODS: Institutional review board approval was obtained for this study; the need for patient informed consent was waived. Clinical, pathologic, and imaging findings were retrospectively evaluated in 22 men (mean age, 64.5 years) with HCC and NAFLD. Helical CT and MR images were reviewed for morphologic features such as tumor size, margins, necrosis, and degree of enhancement. RESULTS: Obesity, diabetes, and hypertension were common findings and were observed in 12 (55%), 14 (64%), and 13 (59%) of the 22 patients, respectively. The serum alpha-fetoprotein level was elevated in eight patients (36%). All patients had pathologic evidence of NAFLD. HCC was well-differentiated in seven patients, moderately differentiated in 11, and poorly differentiated in four. Large tumors (mean diameter, 8.4 cm) were depicted at CT and/or MR imaging in all patients. Twenty-one patients had a solitary or dominant mass. At imaging, tumor margins were well defined in 17 patients, with a smooth surface in 17, and there was evidence of a tumor capsule in 15. Necrosis was depicted in 16 patients. There was no evidence of calcifications, central scar, fat, or abdominal lymphadenopathy. CT was performed in 20 patients. HCC was hypoattenuating on unenhanced CT scans in 14 patients, heterogeneously hyperattenuating in the arterial phase in 20, and hypoattenuating in the portal phase in 14. MR imaging was performed in 16 patients. HCC was hyperintense compared with liver parenchyma at T2-weighted MR imaging in all 16 patients, hypointense at T1-weighted imaging in 14, heterogeneously hyperintense at arterial phase T1-weighted imaging in 16, and hypointense at portal phase T1-weighted imaging in 14. CONCLUSION: HCC in patients with NAFLD is more likely to manifest as a large solitary or dominant mass characterized by smooth and possibly encapsulated margins, necrosis, and hypervascularity.     

Thoracic involvement of type A aortic dissection and intramural hematoma: diagnostic accuracy--comparison of emergency helical CT and surgical findings

PURPOSE: To assess the accuracy of various findings at emergency helical computed tomography (CT) for the evaluation of thoracic involvement of type A aortic dissection (AD) and type A intramural hematoma (IMH) and to compare these findings with those at surgical confirmation. MATERIALS AND METHODS: Fifty-seven patients with acute chest pain underwent emergency helical CT and subsequent surgery for type A AD or IMH. Patients in whom AD or IMH was detected in three segments of the thoracic aorta or those in whom there was a site of any entry tear, arch branch vessel involvement, pericardial effusion, or aortic arch anomaly were examined at helical CT. Sensitivity, specificity, and accuracy of helical CT, along with 95% CIs, were calculated by using surgical confirmation as the reference standard. RESULTS: For the detection of AD or IMH of the thoracic aorta, the accuracy of helical CT was 100%. The sensitivity, specificity, and accuracy, respectively, were 82%, 100%, and 84% for an entry tear; 95%, 100%, and 98% for arch branch vessel involvement; and 83%, 100%, and 91% for pericardial effusion. These values were all 100% for aortic arch anomalies. CONCLUSION: Emergency helical CT of the thorax depicts findings that are highly accurate in the evaluation of acute type A AD and IMH.     

Two-dimensional multiplanar and three-dimensional volume-rendered vascular CT in pancreatic carcinoma: interobserver agreement and comparison with standard helical techniques

OBJECTIVE: The purpose of this study was to compare two-dimensional curved multiplanar and three-dimensional reconstructions, routine axial presentations, and combined techniques in the assessment of vascular involvement by pancreatic malignancy. MATERIALS AND METHODS: For 44 patients with known pancreatic malignancy a total of 56 arterial phase helical CT scans were obtained. Targeted pancreatic imaging was performed, and reformatted images were generated. Axial source images, reformatted images, and the combination of axial and reformatted images were interpreted independently by three observers. The observers graded the celiac axis, common and proper hepatic, splenic, gastroduodenal, and superior mesenteric arteries for tumor involvement. Grades of vascular involvement were compared by intra- and interobserver variability analyses. RESULTS: Intraobserver agreement averaged over five vessels was good between the axial and combined techniques for each individual observer (0.64 < or kappa < or = 0.66), but intraobserver agreement was poor between the axial and reformatted (kappa = 0.17 and kappa = 0.31, respectively) and the reformatted and combined techniques (kappa = 0.31 and kappa = 0.38, respectively) for two observers. For grading of vascular involvement in each vessel, intraobserver agreement was good to excellent between the axial and combined techniques (0.48 or = kappa < or = 0.82). Interobserver agreement averaged over five vessels was poor for imaging techniques except between observer 2 and observer 3 on the axial (kappa = 0.47) and combined techniques (kappa = 0.47). For grading of vascular involvement in each vessel, interobserver agreement for reformatted technique was poor (0.09 < or = kappa < or = 0.40). CONCLUSION: Multiplanar and volume-rendered techniques showed the highest intra- and interobserver variability in grading vascular involvement by pancreatic malignancy. These images should be used in combination with routine axial images to decrease observer variability.     

64层螺旋CT三维重建在气管主支气管肿瘤诊断中的应用

目的 探讨64层螺旋CT三维重建在气管、主支气管肿瘤诊断中的应用价值.方法 39例均接受64层螺旋CT胸部扫描,工作站行气管、支气管三维重建,仿真内窥镜,多平面重组,最小密度投影重建.分析气管、支气管肿瘤的CT表现,并与手术病理和支气管镜检结果进行比较.结果 肿瘤位于气管9例,左主支气管13例,右主支气管15例,病变广泛2例.所有病例均见管腔内充盈缺损影,致管腔1级狭窄1例,2级狭窄0例,3级狭窄14例,4级狭窄24例.管壁无增厚2例,管壁增厚14例,壁厚伴向轮廓外突出23例.宽基底32例,窄基底7例.边缘光滑2例,边缘不规则37例.良性肿瘤3例:良性间叶瘤、平滑肌瘤、多形性腺瘤各1例.恶性病变36例:小细胞未分化癌8例,腺癌1例,鳞状细胞癌25例,黏液表皮样癌1例,甲状腺乳头状癌1例.与病理比较本研究正确诊断率为97.44%,与支气管镜检比较仿真内窥镜对病变近端的显示与支气管镜所见均一致.结论 64层螺旋CT三维重建是气管、主支气管良恶性肿瘤诊断与鉴别诊断、支架植入计划和疗效评价的方便、无创、准确的检查方法.     

Endovascular repair in traumatic thoracic aortic injuries: comparison with open surgical repair

PURPOSE: Thoracic endovascular aortic repair (TEVAR) has emerged as an alternative to open surgical repair (OSR) of traumatic thoracic aortic injury (TTAI). Herein immediate and midterm outcomes of TEVAR are compared with those of OSR. MATERIALS AND METHODS: Health records were used to identify patients with TTAI presenting between April 1995 and September 2006. Preoperative patient characteristics, intraoperative variables, procedural costs, and outcomes were recorded. RESULTS: A total of 103 patients were identified. Twenty-two died before treatment, 19 were treated conservatively, 36 received OSR, and 26 received TEVAR. In the OSR group, time from diagnosis to treatment was 8 hours, the 30-day mortality rate was 11.1%, and all deaths occurred intraoperatively. Thoracic nerve injury occurred in four patients (12.5%), pneumonia in 12 (37.5%), temporary renal failure in one (3%), paraparesis in three (9.4%), and paraplegia in five (15.6%). On follow-up (mean, 61 months), postthoracotomy pleural reaction was seen in three cases (9.4%). In the TEVAR group, time to treatment was 38 hours (P < .01) and the 30-day mortality rate was 7.4% with no intraoperative deaths. Pneumonia was seen in two cases (8.3%) and left arm ischemia was seen in two of 17 patients in whom the left subclavian artery was covered. On midterm follow-up (mean, 17 months), there were no graft failures or repeat aortic interventions. Costs of each procedure were initially comparable, but follow-up expenses with TEVAR were $1,284 (Canadian) greater per year. CONCLUSIONS: TEVAR of TTAI is associated with lower perioperative mortality and morbidity rates than OSR, with no significant graft-related complications on midterm follow-up. The study data support the continued use of TEVAR in this context.     

Multislice helical CT: the value of multiplanar image reconstruction in assessment of the bronchi and small airways disease

We examined 23 consecutive patients (11 males and 12 females with mean age of 56 years) with possible airway diseases to assess the impact of multiplanar image reconstruction (MPR) on the degree of confidence and accuracy in diagnosing bronchial abnormalities and emphysema. The thorax was scanned contiguously at 1 mm slice thickness using Siemens Volume Zoom Multislice CT scanner. Images were reconstructed at 1 mm slice thickness (lung windows L-600HU W-1600HU utilizing high spatial frequency algorithm) in the axial (10 mm apart), sagittal (4 images per lung) and coronal (6 images) plane. Paddle wheel image reconstructions were also performed in the assessment of bronchiectasis. Axial images were assessed with and without the help of MPR by three chest radiologists at two separate occasions (at least 4 weeks apart). The presence of bronchiectasis, emphysema and bronchiolitis in each lobe was documented on a confidence scale of 0 to 3. The overall mean confidence for each observer with and without MPR was compared. Consensus diagnosis was used as the gold standard for the assessment of the diagnostic accuracy of each observer. A confidence score of 2 or more for any lobe was considered diagnostic of the particular airway disease. The diagnostic accuracy for each observer with and without MPR was compared. Consensus reporting diagnosed bronchiectasis in 7 patients (30.4%), bronchiolitis in 5 patients (21.7%) and emphysema in 12 patients (52%). MPR did not increase the confidence of assessing the different abnormalities for all observers but improvement in diagnosing bronchiectasis was noted in two observers. The improvement did not reach statistical significance. However, agreement between observers in the diagnosis of bronchiectasis and emphysema was improved when the MPR images were used in conjunction with standard axial imaging (Kappa statistic improved from 0.29 to 0.54 for bronchiectasis and from 0.7 to 0.81 for emphysema). Agreement on the diagnosis of bronchiolitis was not improved by MPR for all observers. Our results suggest that MPR seems to improve the confidence in diagnosing bronchiectasis and emphysema.     

Dual-slice helical CT of the thoracic aorta

With the advent of helical CT, the capability of noninvasive imaging of the thoracic aorta has been enhanced considerably. In this article, we describe the potential of helical CT using dual-slice technology to evaluate thoracic aortic diseases such dissection, aneurysm, trauma, infection, inflammation, thromboembolic disease, and postoperative complications. Technical considerations for optimal CT imaging as well as limitations of helical CT are highlighted.     

Making the transition: the role of helical CT in the evaluation of potentially acute thoracic aortic injuries

OBJECTIVE: The purpose of this study was to show that helical CT could be used at our center in lieu of routine aortography to examine patients who have had serious blunt chest trauma. We also wanted to assess the potential savings of using CT to avoid unnecessary aortography. MATERIALS AND METHODS: The institutional review board approved the parallel imaging-CT immediately followed by aortography-of patients presenting with blunt chest trauma between August 1997 and August 1998. To screen patients for potential aortic injuries, we performed parallel imaging on 142 patients, and these patients comprised our patient population. CT examinations of the patients were reviewed for signs of injury by radiologists who were unaware of each other's interpretations and the aortographic results. Findings of CT examinations were classified as negative, positive, or inconclusive for injury. Aortography was performed immediately after CT. The technical and professional fees for both transcatheter aortography and helical CT were also compared. RESULTS: Our combined kappa value for all CT interpretations was 0.714. The aortographic sensitivity and negative predictive value were both 100%. Likewise, the sensitivity and negative predictive value of CT were 100%. The total costs of performing aortography were estimated at approximately $402,900, whereas those for performing helical CT were estimated at $202,800. CONCLUSION: Helical CT has a sensitivity and negative predictive value equivalent to that of aortography. Using CT to eliminate the possibility of mediastinal hematoma and to evaluate the cause of an abnormal aortic contour in a trauma patient allows us to use aortography more selectively. Avoiding the performance of unnecessary aortography will expedite patient care and reduce costs. We report the results of our experience with CT and how our center successfully made this transition in the initial examination of patients with serious thoracic trauma.     

Pulmonary and cardiac cysticercosis: helical CT findings

The authors aim to report the chest CT findings of a patient with disseminated cysticercosis, emphasising the pulmonary and cardiac features. The main finding consisted of multiple pulmonary, cardiac and chest wall nodules. The present case demonstrates that cysticercosis should be considered in the differential diagnosis of multiple pulmonary nodules, mainly in those patients with similar lesions in the cardiac muscle and/or in the chest wall.     

CSF leaks: correlation of high-resolution CT and multiplanar reformations with intraoperative endoscopic findings

BACKGROUND AND PURPOSE: Skull base defects can result in CSF leaks, with meningitis as a potential complication. Surgeons are now routinely repairing these leaks via a nasal endoscopic approach. Accurate preoperative imaging is essential for surgical planning. A variety of imaging regimens have been employed, including axial and direct coronal CT, CT cisternography with iodinated contrast, radionuclide cisternography, and MR imaging. Now that multidetector helical CT is available, the purpose of this study was to determine how well coronal and sagittal multiplanar reformatted (MPR) images generated from a high-resolution axial dataset correlate with intraoperative findings in a group of patients with clinically proved CSF leaks.MATERIALS AND METHODS: We retrospectively reviewed imaging findings and surgical records of 19 patients who presented to our tertiary care institution during a 2.5-year period with clinically proved CSF leak. Patients underwent preoperative imaging with high-resolution helical CT (section collimation, 10 patients with 0.625-mm and 9 patients with 1.25-mm images), with MPR images processed by a neuroradiologist at a workstation. Two neuroradiologists, blinded to the intraoperative findings, determined the location and size of the skull base defects. All patients underwent endoscopic evaluation by an experienced sinonasal otolaryngologist, who confirmed the site of the CSF leak by direct inspection and measured the corresponding osseous defect. CT was considered accurate if it correctly localized the CSF leak and was within 2 mm of the endoscopic measurement.RESULTS: At endoscopy, 22 leaks of CSF were identified in 18 of 19 patients. CT correctly predicted the site of the leak in 20 (91%) of 22 cases and was accurate (within 2 mm of the endoscopic measurement) in 15 (75%) of 20 cases preoperatively localized. The CT measurement of the skull base defect differed from the endoscopic size in 5 (25%) of 20 cases, ranging from 7.4 mm below to 13 mm above the intraoperative measurement. When analysis was limited to the subgroup of 10 patients who had 0.625-mm axial images, the accuracy was improved, and of the 11 CSF leaks described at CT, all were verified at endoscopy. In addition, the submillimeter CT accurately measured the size of the osseous defect in 9 (82%) of 11 cases. In the remaining 2 (18%) of 11 cases, CT minimally overestimated the size of the osseous defect by only 3 mm.CONCLUSION: Axial images, and coronal, sagittal, and oblique MPR images generated from high-resolution axial CT performed well preoperatively, localizing the skull base defect responsible for the CSF leak. However, active manipulation of the axial dataset at a workstation is crucial in identifying and correctly describing these lesions. When submillimeter collimation is available, measurement of the osseous defects are accurate most of the time.

Skull base defects that result in dural tears and CSF leaks can be associated with significant long-term disability, primarily related to central nervous system infection. Bacterial meningitis is the major cause of morbidity and mortality, with encephalitis and parenchymal abscess occurring much less frequently¹. Left untreated, some may resolve spontaneously, but the risk for meningitis is 10% annually and up to 40% in the long term.² CSF leaks occur in approximately 2% of closed head injuries, the most common cause of CSF leak.³ Other causes include a tumor or developmental malformations of the skull base, and surgical trauma. CSF leaks may also arise spontaneously, especially in the setting of idiopathic intracranial hypertension. More than 90% of CSF leaks are successfully treated by minimally invasive intranasal endoscopic repair.^2,3 Even when CSF leaks cease spontaneously, early endoscopic repair is often considered because of a significant risk, estimated at 30% to 40%, for ascending meningitis.³In patients with profuse posttraumatic or postsurgical CSF leaks, the diagnosis is obvious. However, in patients with intermittent CSF leaks that result in minimal discharge, the diagnosis may remain elusive. In this circumstance, beta2-transferrin (β₂-TF) assay provides a highly sensitive and specific (97% and 99%, respectively) method to confirm CSF leak.⁴ β₂-TF protein is found almost exclusively in CSF, and as little as 0.5 mL of CSF is needed for the assay.³ Once the clinical suspicion of CSF leak is confirmed with β₂-TF, the skull base defect responsible for the leak must be identified.A variety of diagnostic modalities have been proposed for the preoperative localization of CSF leaks. In the traditional sense, CT and radionuclide cisternography have been the mainstays in the diagnostic evaluation, but their accuracy diminishes when CSF leaks are intermittent, a frequent occurrence. More recently, high-resolution CT without intrathecal contrast and with the use of axial and direct coronal planes has been shown to reliably demonstrate skull base defects that result in CSF leaks.^5,6 With this technique, the skull base defect can be localized even when there is no active leak. Given that coronal images are essential in identifying skull base defects, the purpose of our study was to determine how well high-resolution coronal, sagittal, and oblique multiplanar reformatted (MPR) images generated from an axial dataset correctly predict the site of a CSF leak. It is perhaps more important to note that our series is the first, to our knowledge, to evaluate how accurately CT measurements compare with intraoperative sizes of the responsible skull base defects.