Variation in Maximum Diameter Measurements of Descending Thoracic Aortic Aneurysms Using Unformatted Planes versus Images Corrected to Aortic Centerline
Abstract:Corrected diameters were smaller than axial diameters, could be measured with higher repeatability, and were subject to less interobserver variability. Using corrected versus axial measurements would have changed management decisions in up to half of the cases in this study.
“…Since then, and along with the transition to 3D imaging, the semiautomated centreline method has become routinely available. Multiple previous studies have reported that axial measurements significantly overestimate diameters when compared with centreline methods, especially in more tortuous aortic segments 25 26. Based on these observations, it has been argued that current guidelines are not adapted to the use of centreline measurements and that the surgical threshold should be shifted to smaller TAA sizes 27.…”
ObjectiveManagement of thoracic aortic aneurysms (TAAs) comprises regular diameter follow-up until the indication criterion for prophylactic surgery is reached. However, this approach is unable to predict the majority of acute type A aortic dissections (ATAADs). The current study aims to evaluate the diagnostic accuracy of ascending aortic diameter, length and volume for occurrence of ATAAD.MethodsThis two-centre observational cohort study retrospectively screened 477 consecutive patients who presented with ATAAD between 2009 and 2018. Of those, 25 (5.2%) underwent CT angiography (CTA) within 2 years before dissection onset. Aortic diameter, length and volume of these patients (‘pre-ATAAD’) were compared with those of TAA controls (n=75). Receiver operating curve analysis was performed to evaluate the predictive accuracy of the three different measurements.Results96% of patients with pre-ATAAD did not meet the surgical diameter threshold of 55 mm before dissection onset. Maximal aortic diameters (45 (40–49) mm vs 46 (44–49) mm, p=0.075) and volume (126 (95–157) cm3 vs 124 (102–136) cm3, p=0.909) were comparable between patients with pre-ATAAD and TAA controls. Conversely, ascending aortic length (84±9 mm vs 90±16 mm, p=0.031) was significantly larger in patients with pre-ATAAD. All three parameters had an area under the curve of >0.800. At the 55 mm cut-off point, the maximal diameter yielded a positive predictive value (PPV) of 20%. While maintaining same specificity levels, measurements of aortic volume and length showed superior diagnostic accuracy (PPV 55% and 70%, respectively).ConclusionMeasurements of aortic volume and length have superior diagnostic accuracy compared with the maximal diameter and could improve the timely identification of patients at risk for ATAAD.
“…Since then, and along with the transition to 3D imaging, the semiautomated centreline method has become routinely available. Multiple previous studies have reported that axial measurements significantly overestimate diameters when compared with centreline methods, especially in more tortuous aortic segments 25 26. Based on these observations, it has been argued that current guidelines are not adapted to the use of centreline measurements and that the surgical threshold should be shifted to smaller TAA sizes 27.…”
ObjectiveManagement of thoracic aortic aneurysms (TAAs) comprises regular diameter follow-up until the indication criterion for prophylactic surgery is reached. However, this approach is unable to predict the majority of acute type A aortic dissections (ATAADs). The current study aims to evaluate the diagnostic accuracy of ascending aortic diameter, length and volume for occurrence of ATAAD.MethodsThis two-centre observational cohort study retrospectively screened 477 consecutive patients who presented with ATAAD between 2009 and 2018. Of those, 25 (5.2%) underwent CT angiography (CTA) within 2 years before dissection onset. Aortic diameter, length and volume of these patients (‘pre-ATAAD’) were compared with those of TAA controls (n=75). Receiver operating curve analysis was performed to evaluate the predictive accuracy of the three different measurements.Results96% of patients with pre-ATAAD did not meet the surgical diameter threshold of 55 mm before dissection onset. Maximal aortic diameters (45 (40–49) mm vs 46 (44–49) mm, p=0.075) and volume (126 (95–157) cm3 vs 124 (102–136) cm3, p=0.909) were comparable between patients with pre-ATAAD and TAA controls. Conversely, ascending aortic length (84±9 mm vs 90±16 mm, p=0.031) was significantly larger in patients with pre-ATAAD. All three parameters had an area under the curve of >0.800. At the 55 mm cut-off point, the maximal diameter yielded a positive predictive value (PPV) of 20%. While maintaining same specificity levels, measurements of aortic volume and length showed superior diagnostic accuracy (PPV 55% and 70%, respectively).ConclusionMeasurements of aortic volume and length have superior diagnostic accuracy compared with the maximal diameter and could improve the timely identification of patients at risk for ATAAD.
“…Five different measurement parameters were selected in this study, which included all measurement parameters in current literature, and all these parameters were automatically obtained on the post-processing software with high repeatability. The measurement of each parameter was made based on a centerline method, which has been verified with higher repeatability than unformatted axial images ( 15 ). Meanwhile, one purpose of this study was to study whether other measurements rather than the traditional maximum aortic diameter have a smaller change rate between the systolic and diastolic phases and could be used as a reference for stent selection at the aortic arch and proximal descending thoracic aorta, which has been seldom reported, especially at level B (no relevant reports have been published).…”
Section: Discussionmentioning
confidence: 99%
“…The syngo.CT Vascular Analysis (Syngo.via, Siemens Healthcare GmbH, Erlangen, Germany) is a commercially available software. A protocol for the measurement of different parameters using the centerline method was established ( 15 ). This protocol was set to ensure measurements during the systolic and diastolic phases.…”
BackgroundTo characterize the difference in aortic dimensions during the cardiac cycle with electrocardiogram (ECG)-gated computed tomography angiography (CTA) and to determine whether other parameters in comparison to diameter could potentially provide a more accurate size reference for stent selection at the aortic arch and the proximal thoracic descending aorta.MethodsThe CTA imaging of 90 patients during the cardiac cycle was reviewed. Three anatomic locations were selected for analysis (level A: 1 cm proximal to the innominate artery; level B: 1 cm distal to the left common carotid artery; and level C: 1 cm distal to the left subclavian artery). We measured the maximum diameter, the minimum diameter, the lumen area, the lumen perimeter, and the diameter derived from the lumen area, and the changes of each parameter at each level during the cardiac cycle were compared.ResultsThe mean age was 60.9 ± 12.4 years (range, 16–78 years). There was a significant difference in the aortic dimensions during the cardiac cycle (p < 0.001). The diameter derived from the lumen area at all three levels was changed least over time when compared to the area, perimeter, and the maximum aortic diameter (all p < 0.01).ConclusionThe aortic dimensional differences during the cardiac cycle are significant. The aortic diameter derived from the lumen area over other parameters may provide a better evaluation for selecting the size of the stent at the aortic arch and the proximal thoracic descending aorta. A prospective study comparing these different measurement parameters regarding the outcomes is still needed to evaluate the clinical implications.
“…Therefore, diameters can vary slightly depending on trigger time (end-systolic vs. end-diastolic) and edge selection (leading edge-to-leading edge vs. inner edge-inner edge vs. outer edge-outer edge). In general, it is stressed that measurements should be performed perpendicular to the aortic centerline (i.e., on double oblique images), and that measurement location and methodology should be specified in order to provide for accurate follow-up in individuals with an indication for repetitive imaging [11–13]. Fig.…”
Section: Best Current Practice—aortic Diametersmentioning
Acute aortic syndromes comprise a group of potentially fatal conditions that result from weakening of the aortic vessel wall. Pre-emptive surgical intervention is currently reserved for patients with severe aortic dilatation, although abundant evidence describes the occurrence of dissection and rupture in aortas with diameters below surgical thresholds. Modern imaging techniques (such as hybrid PET-CT and 4D flow MRI) afford the non-invasive assessment of anatomic, hemodynamic, and molecular features of the aorta, and may provide for a more accurate selection of patients who will benefit from preventative surgical intervention. In the current review, we summarize evidence and considerations regarding predictive aortic imaging and highlight evolving imaging modalities that have shown promise to improve risk assessment for the occurrence of dissection and rupture.Key Points
• Guidelines for the preventative management of aortic disease depend on maximal vessel diameters, while these have shown to be poor predictors for the occurrence of catastrophic acute aortic events.
• Evolving imaging modalities (such as 4D flow MRI and hybrid PET-CT) afford a more comprehensive insight into anatomic, hemodynamic, and molecular features of the aorta and have shown promise to detect vessel wall instability at an early stage.
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