Multimodality Noninvasive Imaging of Thoracic Aortic Aneurysms: Time to Standardize?

Dynamic aortic changes during the cardiac cycle in patients with aortic valve disease analyzed by computed tomography combined with PhyZiodynamics software

BACKGROUND

Endovascular therapy for the ascending aorta is expected in the future, but the dynamic changes in the ascending aorta are unclear.

PURPOSE

The purpose of the present study was to evaluate dynamic changes in the aortic cross-sectional area and examine related determinants.

METHODS

The subjects included 75 patients (aortic regurgitation [AR] in 18 patients, aortic stenosis [AS] in 46 patients, and 11 controls) who underwent dynamic computed tomography (CT) prior to cardiac treatment. According to the centerline method, the cross-sectional areas of the ascending and descending aortas at the same level were analyzed. The rate of change from the minimum value to the maximum value in one heartbeat and peak rate of change in cross-sectional area (peak area change) were measured.

RESULTS

The rates of change of the ascending and descending aortas were 4.4% and 6.4% (P < 0.05) and the peak area change was 0.3 mm2/msec vs. 0.2 mm2/msec (P < 0.05), respectively. In both the ascending and descending aortas, the rate of change and the peak area change were significantly greater in the AR group than in the AS and control groups. Results of the multiple regression analysis showed that greater stroke volumes (SVs) were associated with greater change in the ascending aorta and a faster momentary expansion rate. Furthermore, it was observed that the momentary expansion rate declined with age.

CONCLUSION

The ascending aortic diameter changes significantly in one heartbeat and differs depending on AR, age, and SV.

TRIAL REGISTRATION NUMBER

17 - 006.

DATE OF REGISTRATION

May 29, 2017 Retrospectively registered.

ACR Appropriateness Criteria® Thoracoabdominal Aortic Aneurysm or Dissection: Treatment Planning and Follow-Up

As the incidence of thoracoabdominal aortic pathology (aneurysm and dissection) rises and the complexity of endovascular and surgical treatment options increases, imaging follow-up of patients remains crucial. Patients with thoracoabdominal aortic pathology without intervention should be monitored carefully for changes in aortic size or morphology that could portend rupture or other complication. Patients who are post endovascular or open surgical aortic repair should undergo follow-up imaging to evaluate for complications, endoleak, or recurrent pathology. Considering the quality of diagnostic data, CT angiography and MR angiography are the preferred imaging modalities for follow-up of thoracoabdominal aortic pathology for most patients. The extent of thoracoabdominal aortic pathology and its potential complications involve multiple regions of the body requiring imaging of the chest, abdomen, and pelvis in most patients. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Aortic Dimensions Are Larger in Patients With Fibromuscular Dysplasia

Background Fibromuscular dysplasia (FMD) is a disease of unknown etiology that causes stenosis, aneurysmal dilatation, and dissection of vascular beds. Known to affect medium-sized arteries, FMD is not typically considered to affect the aorta. We tested the hypothesis that aortic size in FMD is abnormal compared with age- and sex-matched controls. Methods and Results Medical records and computed tomography angiography images were reviewed in female patients with a diagnosis of FMD who were seen in the vascular medicine clinic at Emory Healthcare. Aortic dimensions were measured at 6 different landmarks. Using 2 sample t tests, the aortic measurements and height-indexed measurements were compared with published normal values in healthy women of a similar age. A total of 94 female patients were included in the study. The median age was 57 (interquartile range, 50-65). FMD involvement was present most commonly in the extracranial carotid (77.7%) and renal (43.6%) arteries. All 6 aortic segments were found to be larger in both absolute measures and height-indexed measures in the FMD population (P<0.001). The largest differences were observed within the absolute measures of the sinotubular junction with mean±SD (mm) (29.9±4.1) versus (27±2.5), ascending aorta (32.7±4.4) versus (30.0±3.5), and descending aorta (24.7±3.0) versus (22.0±2.0) (P<0.001). Conclusions Aortic diameters in female patients with FMD are larger when compared with published age- and sex-matched normal values. These findings suggest that FMD may also affect the large-sized arteries.

Interdisziplinäre Betreuung von Menschen mit Marfan-Syndrom – Pharmakologie, Schwangerschaft, Auge, Skelett und organisatorische Aspekte

Im ersten Teil des vorliegenden Beitrags wurde im Detail auf die Genetik, Diagnose, Differenzialdiagnose, die diagnostische Bildgebung, Follow-up, die kardiovaskulären Probleme sowie die Manifestation an Aorta und den großen Gefäßen bei Patienten mit dem Marfan-Syndrom (MFS) eingegangen. In diesem zweiten Teil werden die medikamentöse Therapie des MFS, seine Bedeutung im Zusammenhang mit einer Schwangerschaft, die Beteiligung von Augen und Wirbelsäule bei MFS-Patienten sowie die organisatorischen Aspekte einer Marfan-Sprechstunde erläutert. Das MFS ist mit einer Prävalenz von etwa 1–2:10.000 die häufigste hereditäre Bindegewebserkrankung mit vaskulärer Komponente. Ursache sind Mutationen im Gen, das für das extrazelluläre Matrixprotein Fibrillin‑1 kodiert. Die Erkrankung wird autosomal-dominant vererbt. Es handelt sich um eine Multisystemerkrankung mit Beteiligung der Aorta, der Mitralklappe, Augen- und Skelettveränderungen. Die Augen- und/oder die Wirbelsäulenbeteiligung sind nicht zu unterschätzen, da sowohl die Skoliose als auch die Linsendislokation etwa 60 % der Patienten mit MFS betreffen. Bis anhin konnte kein Wirkstoff einen klaren Vorteil hinsichtlich klinischer Ereignisse in MFS-Patienten zeigen. Es besteht jedoch der allgemeine Konsens, Patienten mit MFS einen β‑Rezeptoren- oder Angiotensinrezeptorblocker isoliert oder als Kombinationstherapie zu verabreichen. Bei bestehendem Kinderwunsch muss ein besonderes Augenmerk auf die Planung der Schwangerschaft gelegt werden. Im Fall eines Aortenwurzeldurchmessers > 4–4,5 cm empfiehlt sich, entweder einen prophylaktischen Aortenwurzelersatz zu erwägen oder von einer Schwangerschaft abzuraten. Eine strukturierte Langzeitbetreuung ist für Patienten mit MFS essenziell.

Thoracic aortic size in Brazilian smokers: measures using low-dose chest computed tomography anatomical and epidemiological assessment

OBJECTIVES

Thoracic aortic aneurysms (TAAs) represent one-third of the hospitalizations for aortic diseases. The prevalence rate depends on the definition of the normal size of the aorta, which is quite variable, depending on the population studied. The aim of this study was to evaluate the characteristics of the thoracic aorta of Brazilian smokers, identifying the normal size of the aorta, presence of anatomical variations, and prevalence of TAA.

MATERIALS AND METHODS

A total of 711 patients underwent radiological evaluation with low-dose computed tomography (CT) from January 2013 to July 2014 with the initial objective of lung nodule tracking. Two examiners evaluated these images, and measurements of maximum and serial diameters were performed manually in true orthogonal planes. Serial diameter measurements were taken every 2 cm in the ascending aorta and 5 cm in the descending segment. We searched for anatomical variations, aortic arch type, and correlations between anatomical characteristics, sex, body mass index, and body surface area (BSA).

RESULTS

The maximum diameters were 33.61 (standard deviation [SD] 3.88), 28.66 (SD 2.89), and 28.36 mm (SD 3.09) for the ascending segment, aortic arch, and descending segment, respectively. A positive correlation was found between male sex, age, and BSA and aorta diameter. The bovine arch was the most common variation of the aortic arch type, and we found one (0.14%) case of TAA.

CONCLUSIONS

This study with low-dose CT allowed the determination of the mean diameters of the ascending aorta, aortic arch, and descending aorta in Brazilian smokers and TAA prevalence.

Self-navigated 3D whole-heart MRA for non-enhanced surveillance of thoracic aortic dilation: A comparison to CTA

PURPOSE

To prospectively compare image quality and reliability of a non-contrast, self-navigated 3D whole-heart magnetic resonance angiography (MRA) sequence with contrast-enhanced computed tomography angiography (CTA) for sizing of thoracic aortic aneurysm (TAA).

METHODS

Self-navigated 3D whole-heart 1.5 T MRA was performed in 20 patients (aged 67 ± 9 years, 75% male) for sizing of TAA; a subgroup of 18 (90%) patients underwent additional contrast-enhanced CTA on the same day. Subjective image quality was scored according to a 4-point Likert scale and ratings between observers were compared by Cohen's Kappa statistics. For MRA, subjective motion blurring and signal inhomogeneity was rated according to a 3-point scale, respectively. Objective signal inhomogeneity of MRA was quantified as standard deviation of the voxel intensities in a circular region of interest (ROI) placed in the ascending aorta divided by their mean value. Continuous MRA and CTA measurements were analyzed with regression and Bland-Altman analysis.

RESULTS

Overall subjective image quality as rated by two observers was 1 [interquartile range (IQR) 1-2] for self-navigated MRA and 1.5 [IQR 1-2] for CTA (p = 0.717). For MRA, perfect inter-observer agreement was found regarding presence of artefacts and subjective image sharpness (κ = 1). Subjective signal inhomogeneity agreed moderately between the observers (κ = 0.58, p = 0.007), however, it correlated strongly with objectively quantified inhomogeneity of the blood pool signal (r = 0.78, p < 0.0001). Maximum diameters of TAA as measured by self-navigated MRA and CTA showed very strong correlation (r = 0.99, p < 0.0001) without significant inter-method bias (bias -0.03 mm, lower and upper limit of agreement -0.74 and 0.68 mm, p = 0.749). Inter-observer correlation of aortic aneurysm as measured by MRA was very strong (r = 0.96) without significant bias (p = 0.695).

CONCLUSION

Self-navigated 3D whole-heart MRA enables reliable contrast- and radiation free aortic dilation surveillance without significant difference to standardized CTA while providing predictable acquisition time and offering excellent image quality.

Familial Aortopathies - State of the Art Review

Aortopathies are conditions that result in aortic dilatation, aneurysm formation and dissection. Familial aortopathies (perhaps better known as heritable thoracic aortic aneurysm and dissection, h-TAAD, as not all have a positive family history) are recognised to have an underlying genetic cause and affect the aorta, predisposing it to the above pathologies. These conditions can also affect the extra-aortic vasculature, particularly large elastic arteries and other body systems. Mutations in a number of genes have been associated with h-TAAD. However, not all affected families have a pathogenic gene variant identified-highlighting the importance of a three-generational family history and the likely role of both environmental factors and future gene discoveries in furthering knowledge. Survival has improved over the last few decades, essentially due to surgical intervention. The benefit of identifying affected individuals depends upon a regular surveillance program and timely referral for surgery before complications such as dissection. Further research is required to appreciate fully the effects of individual gene variants and improve evidence for prophylactic medical therapy, as well as to understand the effect of h-TAAD on quality of life and life choices, particularly around exercise and pregnancy, for affected individuals. This will be complemented by laboratory-based research that seeks to understand the tissue pathways that underlie development of arterial pathology, ideally providing targets for novel medical therapies and a means of non-invasively identifying individuals at increased vascular risk to reduce dissection, which remains a devastating life-threatening event.

Normal values of aortic dimensions assessed by multidetector computed tomography in the Copenhagen General Population Study

Aims

Accurate assessment of aortic dimensions can be achieved using contrast-enhanced computed tomography. The aim of this study was to define normal values and determinants of aortic dimensions throughout multiple key anatomical landmarks of the aorta in healthy individuals from the Copenhagen General Population Study.

Methods and results

The study group consisted of 902 healthy subjects selected from 3000 adults undergoing cardiovascular thoracic and abdominal computed tomography-angiography (CTA), where systematic measurements of aortic dimensions were performed retrospectively. Individuals included were without any of the following predefined cardiovascular risk factors: (i) self-reported angina pectoris; (ii) hypertension; (iii) hypercholesterolaemia; (iv) taking cardiovascular prescribed medication including diuretics, statins, or aspirin; (v) overweight (defined as body mass index ≥30 kg/m2); (vi) diabetes mellitus (self-reported or blood glucose >8 mmol/L); and (vii) chronic obstructive pulmonary disease. Maximal aortic diameters were measured at seven aortic regions: sinuses of Valsalva, sinotubular junction, ascending aorta, mid-descending aorta, abdominal aorta at the diaphragm, abdominal aorta at the coeliac trunk, and infrarenal abdominal aorta. Median age was 52 years, and 396 (40%) were men. Men had significantly larger aortic diameters at all levels compared with women (P < 0.001). Multivariable analysis revealed that sex, age, and body surface area were associated with increasing aortic dimensions.

Conclusion

Normal values of maximal aortic dimensions at key aortic anatomical locations by contrast-enhanced CTA have been defined. Age, sex, and body surface area were significantly associated with these measures at all levels of aorta. Aortic dimensions follow an almost identical pattern throughout the vessel regardless of sex.

Intermodality variation of aortic dimensions: How, where and when to measure the ascending aorta

BACKGROUND

No established reference-standard technique is available for ascending aortic diameter measurements. The aim of this study was to determine agreement between modalities and techniques.

METHODS

In patients with aortic pathology transthoracic echocardiography, computed tomography angiography (CTA) and magnetic resonance angiography (MRA) were performed. Aortic diameters were measured at the sinus of Valsalva (SoV), sinotubular junction (STJ) and tubular ascending aorta (TAA) during mid-systole and end-diastole. In echocardiography both the inner edge-to-inner edge (I-I edge) and leading edge-to‑leading edge (L-L edge) methods were applied, and the length of the aortic annulus to the most cranial visible part of the ascending aorta was measured. In CTA and MRA the I-I method was used.

RESULTS

Fifty patients with bicuspid aortic valve (36 ± 13 years, 26% female) and 50 Turner patients (35 ± 13 years) were included. Comparison of all aortic measurements showed a mean difference of 5.4 ± 2.7 mm for the SoV, 5.1 ± 2.0 mm for the STJ and 4.8 ± 2.1 mm for the TAA. The maximum difference was 18 mm. The best agreement was found between echocardiography L-L edge and CTA during mid-systole. CTA and MRA showed good agreement. A mean difference of 1.5 ± 1.3 mm and 1.8 ± 1.5 mm was demonstrated at the level of the STJ and TAA comparing mid-systolic with end-diastolic diameters. The visible length of the aorta increased on average 5.3 ± 5.1 mmW during mid-systole.

CONCLUSIONS

MRA and CTA showed best agreement with L-L edge method by echocardiography. In individual patients large differences in ascending aortic diameter were demonstrated, warranting measurement standardization. The use of CTA or MRA is advised at least once.

Unplanned stents in thoracic endovascular aortic repair for type B aortic dissection: A 16-year single-center report

Background

Unplanned stents in thoracic endovascular aortic repair mean additional stents implantation beyond the preoperative planning to achieve operation success. This study aimed to reveal the prevalence and consequences of unplanned stents in thoracic endovascular aortic repair for type B aortic dissection and explore the reasons, risk factors and solutions for unplanned stents.

Methods

Retrospectively analysis consecutive patients diagnosed as type B aortic dissection with initial tear originating distal from the left subclavian artery and underwent thoracic endovascular aortic repair from September 1998 to June 2014 in our center.

Results

Under the criteria, this study enrolled 322 patients, with 83 (25.8%) patients in unplanned group. The incidence rate of unplanned stents in thoracic endovascular aortic repair for type B aortic dissection in each year demonstrates as a bimodal curve. The curve showed that, 2003 and, 2004 was the first and highest peak and 2007 was the second peak. There was no difference in five-year survival rate between planned and unplanned patients (log-rank test, p = 0.994). The unplanned group had higher hospitalization expenses (142,699.08 ± 78,446.75 yuan vs. 175,238.58 ± 34,838.01 yuan; p = 0.019), longer operation time (104.50 ± 93.24 min vs. 179.08 ± 142.47 min; p < 0.001) and hospitalization time (17.07 ± 16.62 d vs. 24.00 ± 15.34 d; p = 0.001). The reasons for unplanned stents were type Ia endoleak (46 patients, 55.4%), bird beak (25 patients, 30.1%), and inappropriate shaping of stent (9 patients, 10.8%). Asymptomatic aortic dissection patients had higher incidence of unplanned stents. Short proximal neck length (2.66 ± 0.59 mm vs. 2.50 ± 0.51 mm; p = 0.016), short stent coverage length (154.62 ± 41.12 mm vs. 133.60 ± 44.33 mm; p = 0.002), and large distal stent oversize (75.44±10.77% vs. 82.68±15.80%; p <0.001) were risk factors for unplanned stents in thoracic endovascular aortic repair.

Conclusion

There are some special risk factors and reasons for unplanned stents in thoracic endovascular aortic repair for type B aortic dissection. Knowing these can we reduce the utilization of unplanned stents with appropriate methods.

Automatic measurement of the sinus of Valsalva by image analysis

BACKGROUND AND OBJECTIVES

Despite the importance of the morphology of the sinus of Valsalva in the behavior of heart valves and the proper irrigation of coronary arteries, the study of these sinuses from medical imaging is still limited to manual radii measurements. This paper aims to present an automatic method to measure the sinuses of Valsalva on medical images, more specifically on cine MRI and Xray CT.

METHODS

This paper introduces an enhanced method to automatically localize and extract each sinus of Valsalva edge and its relevant points. Compared to classical active contours, this new image approach enhances the edge extraction of the Sinus of Valsalva. Our process not only allows image segmentation but also a complex study of the considered region including morphological classification, metrological characterization, valve tracking and 2D modeling.

RESULTS

The method was successfully used on single or multiplane cine MRI and aortic CT angiographies. The localization is robust and the proposed edge extractor is more efficient than the state-of-the-art methods (average success rate for MRI examinations=84% ± 24%, average success rate for CT examinations=89% ± 11%). Moreover, deduced measurements are close to manual ones.

CONCLUSIONS

The software produces accurate measurements of the sinuses of Valsalva. The robustness and the reproducibility of results will help for a better understanding of sinus of Valsalva pathologies and constitutes a first step to the design of complex prostheses adapted to each patient.

Aortic Volumetry at Contrast-Enhanced Magnetic Resonance Angiography: Feasibility as a Sensitive Method for Monitoring Bicuspid Aortic Valve Aortopathy

OBJECTIVES

Bicuspid aortic valve patients can develop thoracic aortic aneurysms and therefore require serial imaging to monitor aortic growth. This study investigates the reliability of contrast-enhanced magnetic resonance angiography (CEMRA) volumetry compared with 2-dimensional diameter measurements to identify thoracic aortic aneurysm growth.

MATERIALS AND METHODS

A retrospective, institutional review board-approved, and Health Insurance Portability and Accountability Act-compliant study was conducted on 20 bicuspid aortic valve patients (45 ± 8.9 years, 20% women) who underwent serial CEMRA with a minimum imaging follow-up of 11 months. Magnetic resonance imaging was performed at 1.5 T with electrocardiogram-gated, time-resolved CEMRA. Independent observers measured the diameter at the sinuses of Valsalva (SOVs) and mid ascending aorta (MAA) as well as ascending aorta volume between the aortic valve annulus and innominate branch. Intraobserver/interobserver coefficient of variation (COV) and intraclass correlation coefficient (ICC) were computed to assess reliability. Growth rates were calculated and assessed by Student t test (P < 0.05, significant). The diameter of maximal growth (DMG), defined as the diameter at SOV or MAA with the faster growth rate, was recorded.

RESULTS

The mean time of follow-up was 2.6 ± 0.82 years. The intraobserver COV was 0.01 for SOV, 0.02 for MAA, and 0.02 for volume (interobserver COV: 0.02, 0.03, 0.04, respectively). The ICC was 0.83 for SOV, 0.86 for MAA, 0.90 for DMG, and 0.95 for volume. Average aortic measurements at baseline and (follow-up) were 42 ± 3 mm (42 ± 3 mm, P = 0.11) at SOV, 46 ± 4 mm (47 ± 4 mm, P < 0.05) at MAA, and 130 ± 23 mL (144 ± 24 mL, P < 0.05). Average size changes were 0.2 ± 0.6 mm/y (1% ± 2%) at SOV, 0.5 ± 0.8 mm/y (1% ± 2%) at MAA, 0.7 ± 0.7 mm/y (2% ± 2%) at DMG, and 6 ± 3 mL/y (4% ± 3%) with volumetry.

CONCLUSIONS

Three-dimensional CEMRA volumetry exhibited a larger effect when examining percentage growth, a better ICC, and a marginally lower COV. Volumetry may be more sensitive to growth and possibly less affected by error than diameter measurements.

Multimodality Imaging for Left Ventricular Hypertrophy Severity Grading: A Methodological Review

Left ventricular hypertrophy (LVH), defined by an increase in left ventricular mass (LVM), is a common cardiac finding generally caused by an increase in pressure or volume load. Assessing severity of LVH is of great clinical value in terms of prognosis and treatment choices, as LVH severity grades correlate with the risk for presenting cardiovascular events. The three main cardiac parameters for the assessment of LVH are wall thickness, LVM, and LV geometry. Echocardiography, with large availability and low cost, is the technique of choice for their assessment. Consequently, reference values for LVH severity in clinical guidelines are based on this technique. However, cardiac magnetic resonance (CMR) and computed tomography (CT) are increasingly used in clinical practice, providing excellent image quality. Nevertheless, there is no extensive data to support reference values based on these techniques, while comparative studies between the three techniques show different results in wall thickness and LVM measurements. In this paper, we provide an overview of the different methodologies used to assess LVH severity with echocardiography, CMR and CT. We argue that establishing reference values per imaging modality, and possibly indexed to body surface area and classified per gender, ethnicity and age-group, might be essential for the correct classification of LVH severity.