Impact of quantitatively determined native thoracic aortic tortuosity on endoleak development after thoracic endovascular aortic repair.

OBJECTIVE: The objective of our study was to assess whether there is an association between native thoracic aortic curvature and the development of endoleaks after thoracic endovascular aortic repair. MATERIALS AND METHODS: Quantitative analysis of the native aortic lumen was performed on preprocedural CT angiograms of 40 patients with thoracic aortic aneurysm treated by thoracic endovascular aortic repair. The curvature of the median centerline was measured. Tortuosity indexes were calculated on the basis of the sum of the curvature values within the diseased segment and in the proximal and distal fixation zones. The association between the tortuosity index and endoleak was analyzed. RESULTS: Compared with patients without endoleaks, the tortuosity index of the proximal fixation zone was higher in patients with type Ia endoleak (9.5 vs 1.5 cm(-1), p < 0.01); the tortuosity index of the distal fixation zone was higher in type Ib endoleak patients (6.6 vs 0.5 cm(-1), p < 0.05); and the tortuosity indexes of the proximal fixation zone and of the diseased segment were higher in type III endoleak patients (11.0 vs 1.5 cm(-1), p < 0.01; and 15.8 vs 7.2 cm(-1), p < 0.01, respectively). Patients with a type III endoleak had longer diseased segments and larger mean diameters of the aneurysm than patients without endoleaks (148.6 vs 87.1 mm, p < 0.01; and 75.4 vs 63.2 mm, p < 0.05, respectively). Logistic regression analysis revealed that the risk of a type I or type III endoleak increased as the tortuosity index increased, with a 90% risk of endoleak at a tortuosity index of 10 cm(-1) in the proximal fixation zone. CONCLUSION: Quantification of aortic tortuosity using CT angiograms may help to predict whether an endoleak will develop after thoracic endovascular aortic repair, and this quantification method may become an important tool for risk stratification before thoracic endovascular aortic repair.

Discriminant analysis of native thoracic aortic curvature: risk prediction for endoleak formation after thoracic endovascular aortic repair.

PURPOSE: To determine the association of native thoracic aortic curvature measured from computed tomographic (CT) angiography categorized by discriminant analysis with the development of endoleaks after thoracic endovascular aortic repair (EVAR). MATERIALS AND METHODS: Forty patients (28 men, 12 women; mean age, 74 y; range, 40-89 y) with aortic diseases treated with thoracic EVAR were evaluated. Diseases treated included atherosclerotic aneurysm (n = 27), penetrating atherosclerotic ulcer (n = 4), intramural hematoma (n = 3), mycotic aneurysm (n = 3), and anastomotic pseudoaneurysm (n = 3). Quantitative analysis of native aortic morphology was performed on preprocedural CT angiograms with an original customized computer program, and regional curvature indices in each anatomic segment of the aorta were calculated. Patterns of native thoracic aortic morphology were analyzed by discriminant analysis. The association between the morphologic pattern of the aorta and the presence and type of endoleak was assessed. RESULTS: After leave-one-out cross-validation methods had been applied, the sensitivity, specificity, and accuracy to detect endoleak formation in a new population group by discriminant analysis of the patterns of native aortic curvature were estimated as 84.0%, 58.8%, and 73.8%, respectively. Compared with the no-endoleak group, the type Ia endoleak group had greater curvature at the aortic arch, the type Ib endoleak group had greater curvature at the thoracoabdominal junction, and the type III endoleak group had greater curvature in the midportion of the descending aorta. CONCLUSIONS: Discriminant analysis of native thoracic aortic morphology measured from CT angiography is a useful tool to predict the risk of endoleak formation after thoracic EVAR and should be implemented during treatment planning and follow-up.

Automated tracing of the adventitial contour of aortoiliac and peripheral arterial walls in CT angiography (CTA) to allow calculation of non-calcified plaque burden.

Aortoiliac and lower extremity arterial atherosclerotic plaque burden is a risk factor for the development of visceral and peripheral ischemic and aneurismal vascular disease. While prior research allows automated quantification of calcified plaque in these body regions using CT angiograms, no automated method exists to quantify soft plaque. We developed an automatic algorithm that defines the outer wall contour and wall thickness of vessels to quantify non-calcified plaque in CT angiograms of the chest, abdomen, pelvis, and lower extremities. The algorithm encodes the search space as a constrained graph and calculates the outer wall contour by deriving a minimum cost path through the graph, following the visible outer wall contour while minimizing path tortuosity. Our algorithm was statistically equivalent to a reference standard made by two reviewers. Absolute error was 1.9 ± 2.3% compared to the inter-observer variability of 3.9 ± 3.6%. Wall thickness in vessels with atherosclerosis was 3.4 ± 1.6 mm compared to 1.2 ± 0.4 mm in normal vessels. The algorithm shows promise as a tool for quantification of non-calcified plaque in CT angiography. When combined with previous research, our method has the potential to quantify both non-calcified and calcified plaque in all clinically significant systemic arteries, from the thoracic aorta to the arteries of the calf, over a wide range of diameters. This algorithm has the potential to enable risk stratification of patients and facilitate investigations into the relationships between asymptomatic atherosclerosis and a variety of behavioral, physiologic, pathologic, and genotypic conditions.

Automated quantification of aortoaortic and aortoiliac angulation for computed tomographic angiography of abdominal aortic aneurysms before endovascular repair: preliminary study.

The degree of angulation of abdominal aortic aneurysms (AAAs) has emerged as an important factor in assessing eligibility for endovascular aneurysm repair (EVAR). The authors developed an automatic algorithm that reduces variability of measurement of aortoiliac angulation. For highly structured manual methods, intraobserver variability was 8.2 degrees ± 5.0 (31% ± 20) and interobserver variability was 5.6 degrees ± 2.5 (20% ± 9.1) compared with 0.6 degrees ± 0.8 (2.2% ± 3.6) (intraobserver) and 0.4 degrees ± 0.4 (1.4% ± 1.9) (interobserver) for the automatic algorithm (P < .01). In phantoms, the automatically measured angles were equivalent to reference values (P < .05). This algorithm was also faster than manual methods and has the potential to enhance the clinical utility and reliability of computed tomographic angiography for preoperative assessment for EVAR.

Development and validation of automated 2D-3D bronchial airway matching to track changes in regional bronchial morphology using serial low-dose chest CT scans in children with chronic lung disease.

To address potential concern for cumulative radiation exposure with serial spiral chest computed tomography (CT) scans in children with chronic lung disease, we developed an approach to match bronchial airways on low-dose spiral and low-dose high-resolution CT (HRCT) chest images to allow serial comparisons. An automated algorithm matches the position and orientation of bronchial airways obtained from HRCT slices with those in the spiral CT scan. To validate this algorithm, we compared manual matching vs automatic matching of bronchial airways in three pediatric patients. The mean absolute percentage difference between the manually matched spiral CT airway and the index HRCT airways were 9.4 ± 8.5% for the internal diameter measurements, 6.0 ± 4.1% for the outer diameter measurements, and 10.1 ± 9.3% for the wall thickness measurements. The mean absolute percentage difference between the automatically matched spiral CT airway measurements and index HRCT airway measurements were 9.2 ± 8.6% for the inner diameter, 5.8 ± 4.5% for the outer diameter, and 9.9 ± 9.5% for the wall thickness. The overall difference between manual and automated methods was 2.1 ± 1.2%, which was significantly less than the interuser variability of 5.1 ± 4.6% (p<0.05). Tests of equivalence had p<0.05, demonstrating no significant difference between the two methods. The time required for matching was significantly reduced in the automated method (p<0.01) and was as accurate as manual matching, allowing efficient comparison of airways obtained on low-dose spiral CT imaging with low-dose HRCT scans.

Breast Angiosarcoma: Case Series and Expression of Vascular Endothelial Growth Factor.

PURPOSE: Angiosarcoma of the breast is a rare, malignant tumor for which little is known regarding prognostic indicators and optimal therapeutic regimens. To address this issue, we performed a retrospective analysis of breast angiosarcoma cases seen at Stanford University along with immunohistochemical analysis for markers of angiogenesis. METHODS: Breast angiosarcoma cases seen between 1980 and 2008 were examined. Viable tissue blocks were analyzed for expression of vascular endothelial growth factor and its receptors. RESULTS: A total of 16 cases were identified. Data was collected regarding epidemiology, treatment, response rates, disease-free survival, and the use of various imaging modalities. Five tissue blocks remained viable for immunohistochemical analysis. Vascular endothelial growth factor-A was positively expressed in 3 of these samples. CONCLUSION: Angiosarcoma of the breast is an aggressive malignancy with a propensity for both local recurrence and distant metastases. Angiogenesis inhibition may represent a novel therapeutic modality in this rare, vascular malignancy.

Improved speed of bone removal in computed tomographic angiography using automated targeted morphological separation: method and evaluation in computed tomographic angiography of lower extremity occlusive disease.

We developed an automated algorithm for bone removal in computed tomographic angiographic images that identifies and deletes connections between bone and vessels. Our automated algorithm is significantly faster than manual methods (2.45 minutes vs 73 minutes) and only generates about 2 small artifactual deletions per patient, mostly in the region of the ankle. Image quality was equivalent to manual methods. It shows promise as a tool for fast and accurate postprocessing of computed tomographic angiograms.

Semiautomated quantification of the mass and distribution of vascular calcification with multidetector CT: method and evaluation.

Institutional review board approval was obtained for this HIPAA-compliant study. Informed consent was obtained for prospective evaluation in 21 asymptomatic volunteers (10 women, 11 men; mean age, 60 years) but waived for retrospective (10 patients with and five patients without disease) evaluation. Prospective validation was in phantoms. Quantification of mass and calcium distribution was performed with fast semiautomated method, without calibration. For actual versus measured mass in phantoms, R(2) was 0.98; absolute and percentage errors were 1.2 mg and 9.1%, respectively. In asymptomatic volunteers, mean interscan variability for calcium mass quantification in extracoronary arteries was 24.9 mg; mean was 991 units for Agatston scoring. In coronary arteries, mean variability was 5.5 mg; mean Agatston variability was 27.7 units. At retrospective computed tomography, mean total calcified mass was 321.3 mg. Accurate quantification of mass and distribution of calcification in simulated arteries with this method can be applied in vivo, with low interscan variability.

Abnormal findings on routine upper GI series following laparoscopic Roux-en-Y gastric bypass.

BACKGROUND: The use of postoperative upper GI series (UGIS) after laparoscopic Roux-en-Y gastric bypass (LRYGBP) varies among bariatric surgeons. The authors describe the findings and impact of UGIS after LRYGBP. METHODS: From July 2003 to January 2006, 487 patients undergoing primary LRYGBP at a single academic institution had a single-contrast Gastrografin UGIS performed on the first postoperative day, without complication. Patient and operative demographics were: mean age 43 years, mean BMI 47 kg/m2, female 84%, and laparoscopic 100%. RESULTS: Of the 487 patients, the UGIS revealed 14 (2.9%) major and 88 (15.2%) minor abnormalities. Among the major UGIS abnormalities, 6 (1.2%) demonstrated a gastrojejunal anastomotic (GJA) leak, 8 (1.4%) confirmed complete obstruction at the GJA, and 1 (0.2%) disclosed a communication with the bypassed stomach. For the minor UGIS abnormalities, 45 (9.2%) displayed significant delay in contrast passage through the GJA, 23 (5.0%) had evidence of dilated loops of small and/or large bowel, and 6 (1.2%) verified miscellaneous abnormal findings (malrotation, lower esophageal dysmotility, jejunal clots). Patients with UGIS abnormalities necessitated additional procedures, delayed oral intake and/or longer length of stay (LOS). CONCLUSIONS: UGIS on postoperative day 1 is a useful means of evaluating postoperative LRYGBP anatomy and influenced postoperative care.

Fully automated system for three-dimensional bronchial morphology analysis using volumetric multidetector computed tomography of the chest.

Recent advancements in computed tomography (CT) have enabled quantitative assessment of severity and progression of large airway damage in chronic pulmonary disease. The advent of fast multidetector computed tomography scanning has allowed the acquisition of rapid, low-dose 3D volumetric pulmonary scans that depict the bronchial tree in great detail. Volumetric CT allows quantitative indices of bronchial airway morphology to be calculated, including airway diameters, wall thicknesses, wall area, airway segment lengths, airway taper indices, and airway branching patterns. However, the complexity and size of the bronchial tree render manual measurement methods impractical and inaccurate. We have developed an integrated software package utilizing a new measurement algorithm termed mirror-image Gaussian fit that enables the user to perform automated bronchial segmentation, measurement, and database archiving of the bronchial morphology in high resolution and volumetric CT scans and also allows 3D localization, visualization, and registration.

Radiology on handheld devices: image display, manipulation, and PACS integration issues.

Handheld personal digital assistants (PDAs) have undergone continuous and substantial improvements in hardware and graphics capabilities, making them a compelling platform for novel developments in teleradiology. The latest PDAs have processor speeds of up to 400 MHz and storage capacities of up to 80 Gbytes with memory expansion methods. A Digital Imaging and Communications in Medicine (DICOM)-compliant, vendor-independent handheld image access system was developed in which a PDA server acts as the gateway between a picture archiving and communication system (PACS) and PDAs. The system is compatible with most currently available PDA models. It is capable of both wired and wireless transfer of images and includes custom PDA software and World Wide Web interfaces that implement a variety of basic image manipulation functions. Implementation of this system, which is currently undergoing debugging and beta testing, required optimization of the user interface to efficiently display images on smaller PDA screens. The PDA server manages user work lists and implements compression and security features to accelerate transfer speeds, protect patient information, and regulate access. Although some limitations remain, PDA-based teleradiology has the potential to increase the efficiency of the radiologic work flow, increasing productivity and improving communication with referring physicians and patients.