Calcium scoring in unenhanced and enhanced CT data of the aorta-iliacal arteries: impact of image acquisition, reconstruction, and analysis parameter settings

Using averaged models from 4D ultrasound strain imaging allows to significantly differentiate local wall strains in calcified regions of abdominal aortic aneurysms

Abdominal aortic aneurysms are a degenerative disease of the aorta associated with high mortality. To date, in vivo information to characterize the individual elastic properties of the aneurysm wall in terms of rupture risk is lacking. We have used time-resolved 3D ultrasound strain imaging to calculate spatially resolved in-plane strain distributions characterized by mean and local maximum strains, as well as indices of local variations in strains. Likewise, we here present a method to generate averaged models from multiple segmentations. Strains were then calculated for single segmentations and averaged models. After registration with aneurysm geometries based on CT-A imaging, local strains were divided into two groups with and without calcifications and compared. Geometry comparison from both imaging modalities showed good agreement with a root mean squared error of 1.22 ± 0.15 mm and Hausdorff Distance of 5.45 ± 1.56 mm (mean ± sd, respectively). Using averaged models, circumferential strains in areas with calcifications were 23.2 ± 11.7% (mean ± sd) smaller and significantly distinguishable at the 5% level from areas without calcifications. For single segmentations, this was possible only in 50% of cases. The areas without calcifications showed greater heterogeneity, larger maximum strains, and smaller strain ratios when computed by use of the averaged models. Using these averaged models, reliable conclusions can be made about the local elastic properties of individual aneurysm (and long-term observations of their change), rather than just group comparisons. This is an important prerequisite for clinical application and provides qualitatively new information about the change of an abdominal aortic aneurysm in the course of disease progression compared to the diameter criterion.

Assessment of Aortoiliac Atherosclerotic Plaque on CT in Prostate Cancer Patients Undergoing Treatment

Traditionally, atherosclerotic risk factors for cardiovascular disease and cancer are assessed using coronary artery calcium scoring. However, this neglects the impact of atherosclerotic disease more proximal to the cancer site. This study assesses whether aortoiliac atherosclerotic plaque is associated with prostate cancer. The dataset consisted of abdominopelvic CT of 93 patients with prostate cancer and 186 asymptomatic patients who underwent CT colonography as an age- and gender-matched control group. Agatston scores were measured in the abdominal aorta, common iliac, and internal iliac arteries. The scores were evaluated for associations with age, Framingham risk score, and prostate cancer-related biomarkers, including prostate-specific antigen, Gleason score, tumor location, prostatectomy, androgen deprivation therapy, mortality, and bone metastasis. The atherosclerotic plaque of prostate cancer patients did not differ from the control group (p = 0.22) and was not correlated with any of the prostate cancer-related biomarkers (p > 0.05). However, Agatston scores of abdominal plaques correlated well with age (p < 0.001) and Framingham risk scores (p = 0.002).

A correction score to compare aortic calcification in contrast enhanced and non-contrast measurements from computed tomography scans

BACKGROUND

Aortic wall calcification shows strong promise as a cardiovascular risk factor. While useful for visual enhancement of vascular tissue, enhancement creates heterogeneity between scans with and without contrast. We evaluated the relationship between aortic calcification in routine abdominal computed tomography scans (CT) with and without contrast.

METHODS

Inclusion was limited to those with abdominal CT-scans with and without contrast enhancement within 120 days. Analytic Morphomics, a semi-automated computational image processing system, was used to provide standardized, granular, anatomically indexed measurements of aortic wall calcification from abdominal CT-scans. Aortic calcification area (ACA) and aortic wall calcification percent (ACP) and were the outcomes of interest. Multiple linear regression was used to evaluate the relationship of aortic measurements. Models were further controlled for age and sex. Stratification of measurements by vertebral level was also performed.

RESULTS

A positive association was observed for non-contrast calcification in ACP β 0.74 (95% CI 0.72, 0.76) and ACA β 0.44 (95% 0.43, 0.45). Stratified results demonstrated the highest coefficient of determination at L2 for percent and L3 for area models [R² 0.91 (ACP) 0.74 (ACA)]. Adjusted lumber-level associations between non-contrast and contrast measurements ranged from (β 0.69-0.82) in ACP and (β 0.37-0.54) in ACA.

CONCLUSION

A straightforward correction score for comparison of abdominal aortic calcification measurements in contrast-enhanced and non-contrast scans is discussed. Correction of aortic calcification from CT scans can reduce scan heterogeneity and will be instrumental in creating larger cardiovascular cohorts as well as cardiovascular risk surveillance programs.

Vascular calcification does not predict anastomotic leak or conduit necrosis following oesophagectomy

BACKGROUND

Anastomotic leaks (AL) and gastric conduit necrosis (CN) are serious complications following oesophagectomy. Some studies have suggested that vascular calcification may be associated with an increased AL rate, but this has not been validated in a United Kingdom population.

AIM

To investigate whether vascular calcification identified on the pre-operative computed tomography (CT) scan is predictive of AL or CN.

METHODS

Routine pre-operative CT scans of 414 patients who underwent oesophagectomy for malignancy with oesophagogastric anastomosis at the Queen Elizabeth Hospital Birmingham between 2006 and 2018 were retrospectively analysed. Calcification of the proximal aorta, distal aorta, coeliac trunk and branches of the coeliac trunk was scored by two reviewers. The relationship between these calcification scores and occurrence of AL and CN was then analysed. The Esophagectomy Complications Consensus Group definition of AL and CN was used.

RESULTS

Complication data were available in n = 411 patients, of whom 16.7% developed either AL (15.8%) or CN (3.4%). Rates of AL were significantly higher in female patients, at 23.0%, compared to 13.9% in males (P = 0.047). CN was significantly more common in females, (8.0% vs 2.2%, P = 0.014), patients with diabetes (10.6% vs 2.5%, P = 0.014), a history of smoking (10.3% vs 2.3%, P = 0.008), and a higher American Society of Anaesthesiologists grade (P = 0.024). Out of the 14 conduit necroses, only 4 occurred without a concomitant AL. No statistically significant association was found between calcification of any of the vessels studied and either of these outcomes. Multivariable analyses were then performed to identify whether a combination of the calcification scores could be identified that would be significantly predictive of any of the outcomes. However, the stepwise approach did not select any factors for inclusion in the final models. The analysis was repeated for composite outcomes of those patients with either AL or CN (n = 69, 16.7%) and for those with both AL and CN (n = 10, 2.4%) and again, no significant associations were detected. In the subset of patients that developed these outcomes, no significant associations were detected between calcification and the severity of the complication.

CONCLUSION

Calcification scoring was not significantly associated with Anastomotic Leak or CN in our study, therefore should not be used to identify patients who are high risk for these complications.

Quantification of abdominal aortic calcification: Inherent measurement errors in current computed tomography imaging

Objective

Quantification software for coronary calcification is often used to measure abdominal aortic calcification on computed tomography (CT) images. However, there is no evidence substantiating the reliability and accuracy of these tools in this setting. Differences in coronary and abdominal CT acquisition and presence of intravascular contrast may affect the results of these tools. Therefore, this study investigates the effects of CT acquisition parameters and iodine contrast on automated quantification of aortic calcium on CT.

Methods

Calcium scores, provided in volume and mass, were assessed by automated calcium quantification software on CT scans. First, differences in calcium scores between the abdominal and coronary CT scanning protocols were assessed by imaging a thorax phantom containing calcifications of 9 metrical variations. Second, aortic calcification was quantified in 50 unenhanced and contrast-enhanced clinical abdominal CT scans at a calcification threshold of 299 Hounsfield Units (HU). Also, the lowest possible HU threshold for calcifications was calculated per individual patient and compared to a 130 HU threshold between contrast-enhanced and unenhanced CT images, respectively.

Results

No significant differences in volume and mass scores between the abdominal and the coronary CT protocol were found. However, volume and mass of all calcifications were overestimated compared to the physical volume and mass (volume range: 0–649%; mass range: 0–2619%). In comparing unenhanced versus contrast-enhanced CT images showed significant volume differences for both thresholds, as well as for mass differences for the 130 vs patient-specific threshold (230 ± 22.6 HU).

Conclusion

Calcification scoring on CT angiography tends to grossly overestimate volume and mass suggesting a low accuracy and reliability. These are reduced further by interference of intravascular contrast. Future studies applying calcium quantification tools on CT angiography imaging should acknowledge these issues and apply corrective measures to ensure the validity of their outcomes.

Is aortoiliac calcification linked to colorectal anastomotic leakage? A case-control study

BACKGROUND

Anastomotic leakage in bowel surgery remains a devastating complication. Various risk factors have been uncovered, however, high anastomotic leakage rates are still being reported. This study describes the use of calcification markers of the central abdominal arteries as a prognostic factor for colorectal anastomotic leakage.

METHODS

This case-control study includes clinical data from three different hospitals. Calcium volume and calcium score of the aortoiliac tract were determined by CT-scan analysis. Cases were all patients with anastomotic leakage after a left-sided anastomosis (n = 30). Three controls were randomly matched for each case. Only patients with a contrast-enhanced pre-operative CT-scan were included.

RESULTS

The measurements of the calcium score and calcium volume of the different trajectories showed that there was one significant difference with regard to the right external iliac artery. Multiple regression analysis showed a significant different negative odds ratio of the presence of calcium in the right external iliac artery.

CONCLUSION

This study demonstrates that calcium volume and calcium score of the aortoiliac trajectory does not correlate with the risk of colorectal anastomotic leakage after a left-sided anastomosis.

Calcification of arteries supplying the gastric tube: a new risk factor for anastomotic leakage after esophageal surgery

PURPOSE

To evaluate the association between the amount and location of calcifications of the supplying arteries of the gastric tube, as determined with a vascular calcification scoring system, and the occurrence of anastomotic leakage after esophagectomy with gastric tube reconstruction in patients with esophageal cancer.

MATERIALS AND METHODS

Institutional review board approval was obtained, and the informed consent requirement was waived for this retrospective study. Consecutive patients who underwent elective esophagectomy for cancer with gastric tube reconstruction and cervical anastomosis between 2003 and 2012 were identified from a prospective database. Vascular calcification scores were retrospectively assigned by reviewing the routine preoperative computed tomographic (CT) images. In patients with anastomotic leakage, presence and severity of calcifications of the aorta (score of 0-2), celiac axis (score of 0-2), right postceliac arteries (common hepatic, gastroduodenal, and right gastroepiploic arteries; score of 0-1), and left postceliac arteries (splenic and left gastroepiploic arteries, score of 0-1) along with patient- and procedure-related characteristics were compared with those of patients without leakage by using multivariate logistic regression analysis.

RESULTS

Of 246 patients, 58 (24%) experienced anastomotic leakage. No significant differences in patient-related factors were found between patients with leakage and those without leakage, with the exception of more chronic use of steroids in the leakage group (7% [four of 58] vs 0% [0 of 188], P = .003). At univariate analysis, leakage was more common in patients with calcification of the aorta (27% [28 of 102] and 35% [13 of 37] vs 16% [17 of 107], P = .029) and the right postceliac arteries (55% [six of 11] vs 22% [52 of 235], P = .013). At multivariate analysis, both minor (odds ratio, 2.00; 95% confidence interval: 1.02, 3.94) and major (odds ratio, 2.87; 95% confidence interval: 1.22, 6.72) aortic calcifications were associated with leakage. Also, an independent association with leakage was found for calcifications of the right postceliac arteries (odds ratio, 4.22; 95% confidence interval: 1.24, 14.4).

CONCLUSION

Atherosclerotic calcification of the aorta and right postceliac arteries that supply the gastric tube is an independent risk factor for anastomotic leakage after esophagectomy.