**2. Efficiency and effectiveness of diagnosis of imaging methods**

Commonly used diagnostic imaging methods of aneurysms are computed tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), digital subtraction angiography (DSA) and combinations of FDG with PET and/or CT and PET with CT or MRI. Many research findings indicate that diagnostic efficiency of different imaging methods differs. As intervention procedures depend upon diagnosis, the choice of appropriate diagnostic imaging method for a given case is very important. If the critical characteristics of the swelling are not detected due to the choice of unsuitable imaging method, interventions may not be very suitable. In this study, six types of aortic aneurysms are covered. These are ruptured and intact thoracic aortic aneurysms (rTA and TA), ruptured and intact abdominal aortic aneurysms (rAAA and AAA) and ruptured and intact thoracicoabdominal aortic aneurysms (rTAA and TAA). Surgical repairs by OAR and EVAR are the intervention procedures. The main imaging procedures are CT, MRI, ultrasound and DSA. The subcategorization of data elements is given in **Figure 1**.

Recent advances have made computed tomography angiography (CTA) and magnetic resonance angiography (MRA) as the most useful diagnostic tools for aortic aneurysm. These developments have helped to reduce the procedural risks of transarterial catheterization. Cross-sectional images provide information on the affected blood vessel and length of its affected part, total aortic diameter and diameter of the artery, true vascular diameter which includes patent lumen, the extent of formation of mural thrombus, the distance of diseased wall from critical aortic branches and extravascular pathology. This imaging method is used as a single procedure for diagnosis, procedure planning and post-operative monitoring. It has helped to reduce the rate of morbidity and mortality. Catheter-based angiography is used as an adjunct to treatment procedures. Integrated with contemporary cross-sectional imaging, this method includes uses of carbon dioxide angiography and intravascular ultrasound methods. Multiple imaging is done in which one

#### *Challenges for Intelligent Data Analysis Methods in Medical Image Analysis during Surgical… DOI: http://dx.doi.org/10.5772/intechopen.86711*

pre-contrast imaging series and at least one contrast-enhanced imaging are included. Although contrast injection protocols include a number of parameters, the critical challenge is the optimal delivery of appropriate quantity of contrast to the volume of interest. These protocols need to be carefully determined for each specific situation. CTA has a definite edge over MRA in many respects. Renal impairment prevents the use of iodine contrast agents. Renal protective strategies are used for its mitigation, with a doubtful benefit at times.

CTA is a quick, reliable, simple and non-invasive diagnostic tool for aneurysms and can effectively replace conventional angiography [3]. Therefore, according to Prestigiacomo et al., 3-D CTA can be used as an initial screening tool in place of DSA. Sensitivity and predictive values of 100% were obtained by them. Sensitivity of 2D and 3D CTA to detect very small aneurysms was 98–100% compared to 95% for DSA [5]. CTA accuracy was also 99–100%. Based on these findings, Villablanca et al. recommended the use of CTA with commercial detectors to detect very small aneurysms [6]. Even without pre-operative angiography, pre-operative 3D CTA (instead of DSA angiography) can provide good anatomical information for microsurgical interventions of aneurysms, as was concluded by González-Darder et al. [7]. Forsting in 2005 concluded that CTA can effectively replace DSA and even MRA for diagnosis aneurysm [8]. Hoh et al. demonstrated the possibility of using only CTA instead of DSA for diagnosis and pretreatment planning in patients with ruptured and unruptured aneurysms in Massachusetts General Hospital [9]. In the findings of Karamessini et al., CTA had sensitivity, specificity, positive predictive, negative predictive and accuracy values of 88.7, 100, 100, 80.7, and 92.3%, respectively. The corresponding values for DSA were 87.8, 98, 97.7, 89.1, and 92.9%, respectively [10]. Based on these findings, the authors concluded that CTA and DSA were equally good for detection of aneurysms of 3 mm or more. With 100% detection accuracy, CTA is also useful to detect AcoA and MCA bifurcation aneurysms. According to Matsumoto et al., 3D CTA can effectively replace conventional catheter angiography in the diagnosis and surgery of most ruptured aneurysms [11]. Furthermore, a recent systematic review done by our group in 2015 also supports the use of CTA as an effective substitute for other imaging methods, at least to some extent, in the treatment and diagnosis of AAA [12]. In measuring the volume of aneurysms, CTA, MRA and rotational DSA produced statistically non-significant differences and hence can be considered equally as per the report of Piotin et al. [13].

On the other hand, in a comparative study, Biasi et al. found CTA inadequate to detect small aneurysms occasionally and therefore recommended DSA/3D rotational angiography [14]. Stavropoulos et al. also considered CTA inferior in detecting small aneurysms, and the use of DSA should be continued. Difficulty of detecting small aneurysms using CTA has been reported by many other workers [15]. According to latest study in 2015 by Chung et al., multi-slice 3D CTA offers better image resolution and is hence more useful than single-slice CTA to detect aortic aneurysms for post-EVAR [16]. In another finding, van Gelder [17] supported further investigation of small aneurysms detected by CTA if there is no pretest probability of ruptured aneurysm. Very low probability of clinically significant aneurysms can be detected by CTA when screening is done for unruptured aneurysms.

Some technological improvements include Sailer et al. in 2014 on using fluoroscopy image fusion guidance for CTA in endovascular interventions to reduce iodine contrast dose and procedure duration [18], Deák et al. on automated systems for detection of aortic aneurysms in CTA images [19] and Wada et al. 2014 on combining 3D CTA with 2D CT imaging guidance for clipping surgery [20].

Patient safety is an important aspect of both diagnosis and treatment. Radiation exposure in terms of type, dose and duration and conditions under which imaging is done are of critical importance, and ACR has critical points on these aspects. This applies to treatment also. So, ACR compliance level and other hospital contexts determine the extent to which patient safety is cared for. This is an aspect derivable from the findings of this work. Thus, some of the six dimensions of heath-care

1.How do the algorithms of these imaging methods determine the efficiency and

3.Is there any risk of higher mortality or reduction in mortality by not following/

This chapter tries to answer the above questions based on our recent research

2.Why is DSA preferred over other imaging methods for the diagnosis of

following ACR appropriateness guidelines for diagnostic imaging?

**2. Efficiency and effectiveness of diagnosis of imaging methods**

Commonly used diagnostic imaging methods of aneurysms are computed tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), digital subtraction angiography (DSA) and combinations of FDG with PET and/or CT and PET with CT or MRI. Many research findings indicate that diagnostic efficiency of different imaging methods differs. As intervention procedures depend upon diagnosis, the choice of appropriate diagnostic imaging method for a given case is very important. If the critical characteristics of the swelling are not detected due to the choice of unsuitable imaging method, interventions may not be very suitable. In this study, six types of aortic aneurysms are covered. These are ruptured and intact thoracic aortic aneurysms (rTA and TA), ruptured and intact abdominal aortic aneurysms (rAAA and AAA) and ruptured and intact thoracicoabdominal aortic aneurysms (rTAA and TAA). Surgical repairs by OAR and EVAR are the intervention procedures. The main imaging procedures are CT, MRI, ultrasound and DSA.

Recent advances have made computed tomography angiography (CTA) and magnetic resonance angiography (MRA) as the most useful diagnostic tools for aortic aneurysm. These developments have helped to reduce the procedural risks of transarterial catheterization. Cross-sectional images provide information on the affected blood vessel and length of its affected part, total aortic diameter and diameter of the artery, true vascular diameter which includes patent lumen, the extent of formation of mural thrombus, the distance of diseased wall from critical aortic branches and extravascular pathology. This imaging method is used as a single procedure for diagnosis, procedure planning and post-operative monitoring. It has helped to reduce the rate of morbidity and mortality. Catheter-based angiography is used as an adjunct to treatment procedures. Integrated with contemporary cross-sectional imaging, this method includes uses of carbon dioxide angiography and intravascular ultrasound methods. Multiple imaging is done in which one

quality are evaluated in this work.

*Aortic Aneurysm and Aortic Dissection*

aneurysm?

findings.

**26**

So, the following questions are relevant:

effectiveness of diagnosis in the case of aneurysm?

The subcategorization of data elements is given in **Figure 1**.

### **2.1 Why is DSA preferred over other imaging methods for aneurysm detection?**

Many research works and reports [21–24] indicate distinct preference for DSA over other imaging methods when diagnosing a variety of aneurysms. Specific reasons may be related to the availability of instruments, specifically trained staff, costs, convenience, etc. In the case of some specific types of aneurysms, DSA has been shown to be the most suitable one for maximum efficiency and effectiveness. These factors are discussed using scientific evidence.

High resolution makes conventional angiography the most desirable diagnostic tool for aortic aneurysm. It is done at the earliest opportunity of patient presentation after bleeding. With haemorrhage risk being high within the first 24 hours, an early angiogram is necessary for therapeutic decisions. Aortic angiography can locate lesions, reveal the size and shape of aneurysm, detect presence of multiple aneurysms, examine vascular anatomy and its collaterals and evaluate the presence of vasospasm and its intensity.

Comparisons of CTA and DSA done by many workers have been discussed above. Other works related to DSA are reviewed here. More often, DSA is used as a confirmatory or extended test of other imaging methods. For example, although 3D CTA compared very well with DSA, in the experiment, DSA was used for confirmation of the results obtained with 3D CTA in the work of Thurnher et al. [25]. The 3D rotational reconstructed DSA images can improve the assessment of aneurysms [26]. Although CTA can add value to DSA, it can never replace it [27]. In one finding by van Rooij et al., 3D rotational angiography (3DRA) was found superior to DSA, and hence they suggested it as the new gold standard [28]. However, according to Zhang et al. contrast-enhanced dual-energy CTA had better diagnostic image quality at lower radiation dose than 3D DSA. Based on their research [29], Defillo et al. concluded that indocyanine green video-angiography (ICGV) had distinct advantages over intraoperative catheter DSA with respect to rapid feedback and visualizing of local perforators [30]. DSA had better visualization of residual aneurysm and parent artery stenosis which did not limit flow. Based on these findings, they recommended the combined use of the two imaging tools. On the other hand, due to the absence of small neck remnants and some residual aneurysms by ICGV, DSA is necessary for quality of surgery assessment in complex aneurysms. Better image quality is possible with lower dose of radiation, according to the results obtained by Pearl et al. [31].

**2.2 Is there a higher mortality risk if ACR appropriateness guidelines for**

EVAR + CT 38 0.1 0.1 EVAR + MRI 6 0.0 0.1 EVAR + US 259 0.7 0.8 EVAR + DSA 7718 20.2 21.0 EVAR + DSA + CT 95 0.2 21.2 EVAR + DSA + MRI 6 0.0 21.2 EVAR + DSA + US 676 1.8 23.0 OAR + CT 485 1.3 24.3 OAR + MRI 106 0.3 24.5 OAR + US 4620 12.1 36.6 OAR + DSA 20,865 54.5 91.1 OAR + DSA + CT 292 0.8 91.9 OAR + DSA + MRI 69 0.2 92.1 OAR + DSA + US 3028 7.9 100.0

*Challenges for Intelligent Data Analysis Methods in Medical Image Analysis during Surgical…*

**that compliance with ACR guidelines reduced mortality risks?**

Total 38,263 100.0

*Imaging frequencies for different aortic aneurysm types.*

**Medical imaging modalities associated with**

*DOI: http://dx.doi.org/10.5772/intechopen.86711*

**interventional repair**

**Table 2.**

**29**

**diagnostic imaging are not complied with? Alternatively, can it be shown**

**Frequency Valid**

**percent**

**n% %**

**Cumulative percent**

In Canada, ultrasound screening of 65–75-year-old men is done and is costeffective. Relative risk of AAA-related mortality is 0.49 for this group compared to no screen. There is little benefit by screening of men beyond 75 years old. Screening of women over 75 years is not recommended. Individualized check-up of women over 65 years is adequate. No follow-up screening is required for AAA size less than 3 cm. Although annual screening of individuals with 3–4.4 cm is routinely done, evidence for this is weak. Screening every 2 years may be enough. Screening for popliteal aneurysm may be beneficial. There is no benefit by screening men or women less than 65 years. Physical examination can supplement screening wherever necessary. As advances in surgery techniques reduce AAA-related

mortality rates, the cost-effectiveness of screening needs to be reviewed periodically. A set of guidelines on clinical practices for endovascular AAA repair was given by Walker et al. [34]. The guidelines deal with endovascular repair, its indications and contradictions, EVAR requirements of patients, procedural assessment before repair containing detailed imaging methods and scoring systems, endograft types and their suitability, technical aspects of surgical procedure and post-operative management. Another set of guidelines on the same topic was published for European Society for Vascular Surgery [35]. There was also an earlier set of guidelines of Society for Vascular Nursing (SVN) Task Force published by Smith et al. [36]. This covers mostly the nursing and patient care aspects of pre-operative, intraoperative

and post-operative stages. The guidelines use evidence-based best practice

approach. A set of guidelines for peripheral arterial disease was published by Hirsch et al. on behalf of ACC/AHA (American College of Cardiology/American Heart

CO2-DSA gave better results than conventional DS in detecting Type I and Type II direct endoleaks in EVAR procedure. This is because CO2-DSA had higher sensitivity and specificity than conventional DSA [32]. In the studies of Wacker et al., in 2014, C-arm CT is used as a supplementary imaging tool with DSA for better localization and classification of endoleaks than DSA alone in EVAR repair [33].

When EVAR was done using single imaging methods, DSA was most preferred followed by US, CT, and MRI in the decreasing order. When two imaging methods were combined, DSA with US recorded the highest imaging frequency. This was followed by DSA + CT and DSA + MRI. The same trend was observed in the case of OAR also. OAR combinations recorded higher frequencies than EVAR combinations, as OAR was the preferred intervention procedure.

The trend was maintained for each aneurysm type as well. In **Table 2**, overall frequency was highest for AAA followed by TA, rAAA, and TAA in the decreasing order. This reflects the relative incidence and prevalence of aneurysm type rather than any preference of imaging for a specific aneurysm type. More than 70% of all imaging and interventions were done on AAA followed by about 21% for TAA, together accounting for about 90% of all aneurysm care.


*Challenges for Intelligent Data Analysis Methods in Medical Image Analysis during Surgical… DOI: http://dx.doi.org/10.5772/intechopen.86711*

#### **Table 2.**

**2.1 Why is DSA preferred over other imaging methods for aneurysm detection?**

Many research works and reports [21–24] indicate distinct preference for DSA over other imaging methods when diagnosing a variety of aneurysms. Specific reasons may be related to the availability of instruments, specifically trained staff, costs, convenience, etc. In the case of some specific types of aneurysms, DSA has been shown to be the most suitable one for maximum efficiency and effectiveness.

High resolution makes conventional angiography the most desirable diagnostic tool for aortic aneurysm. It is done at the earliest opportunity of patient presentation after bleeding. With haemorrhage risk being high within the first 24 hours, an early angiogram is necessary for therapeutic decisions. Aortic angiography can locate lesions, reveal the size and shape of aneurysm, detect presence of multiple aneurysms, examine vascular anatomy and its collaterals and evaluate the presence

Comparisons of CTA and DSA done by many workers have been discussed above. Other works related to DSA are reviewed here. More often, DSA is used as a confirmatory or extended test of other imaging methods. For example, although 3D CTA compared very well with DSA, in the experiment, DSA was used for confirmation of the results obtained with 3D CTA in the work of Thurnher et al. [25]. The 3D rotational reconstructed DSA images can improve the assessment of aneurysms [26]. Although CTA can add value to DSA, it can never replace it [27]. In one finding by van Rooij et al., 3D rotational angiography (3DRA) was found superior to

DSA, and hence they suggested it as the new gold standard [28]. However,

according to Zhang et al. contrast-enhanced dual-energy CTA had better diagnostic image quality at lower radiation dose than 3D DSA. Based on their research [29], Defillo et al. concluded that indocyanine green video-angiography (ICGV) had distinct advantages over intraoperative catheter DSA with respect to rapid feedback and visualizing of local perforators [30]. DSA had better visualization of residual aneurysm and parent artery stenosis which did not limit flow. Based on these findings, they recommended the combined use of the two imaging tools. On the other hand, due to the absence of small neck remnants and some residual

aneurysms by ICGV, DSA is necessary for quality of surgery assessment in complex aneurysms. Better image quality is possible with lower dose of radiation, according

CO2-DSA gave better results than conventional DS in detecting Type I and Type II direct endoleaks in EVAR procedure. This is because CO2-DSA had higher sensitivity and specificity than conventional DSA [32]. In the studies of Wacker et al., in 2014, C-arm CT is used as a supplementary imaging tool with DSA for better localization and classification of endoleaks than DSA alone in EVAR

When EVAR was done using single imaging methods, DSA was most preferred followed by US, CT, and MRI in the decreasing order. When two imaging methods were combined, DSA with US recorded the highest imaging frequency. This was followed by DSA + CT and DSA + MRI. The same trend was observed in the case of OAR also. OAR combinations recorded higher frequencies than EVAR combina-

The trend was maintained for each aneurysm type as well. In **Table 2**, overall frequency was highest for AAA followed by TA, rAAA, and TAA in the decreasing order. This reflects the relative incidence and prevalence of aneurysm type rather than any preference of imaging for a specific aneurysm type. More than 70% of all imaging and interventions were done on AAA followed by about 21% for TAA,

These factors are discussed using scientific evidence.

of vasospasm and its intensity.

*Aortic Aneurysm and Aortic Dissection*

to the results obtained by Pearl et al. [31].

tions, as OAR was the preferred intervention procedure.

together accounting for about 90% of all aneurysm care.

repair [33].

**28**

*Imaging frequencies for different aortic aneurysm types.*

## **2.2 Is there a higher mortality risk if ACR appropriateness guidelines for diagnostic imaging are not complied with? Alternatively, can it be shown that compliance with ACR guidelines reduced mortality risks?**

In Canada, ultrasound screening of 65–75-year-old men is done and is costeffective. Relative risk of AAA-related mortality is 0.49 for this group compared to no screen. There is little benefit by screening of men beyond 75 years old. Screening of women over 75 years is not recommended. Individualized check-up of women over 65 years is adequate. No follow-up screening is required for AAA size less than 3 cm. Although annual screening of individuals with 3–4.4 cm is routinely done, evidence for this is weak. Screening every 2 years may be enough. Screening for popliteal aneurysm may be beneficial. There is no benefit by screening men or women less than 65 years. Physical examination can supplement screening wherever necessary. As advances in surgery techniques reduce AAA-related mortality rates, the cost-effectiveness of screening needs to be reviewed periodically.

A set of guidelines on clinical practices for endovascular AAA repair was given by Walker et al. [34]. The guidelines deal with endovascular repair, its indications and contradictions, EVAR requirements of patients, procedural assessment before repair containing detailed imaging methods and scoring systems, endograft types and their suitability, technical aspects of surgical procedure and post-operative management. Another set of guidelines on the same topic was published for European Society for Vascular Surgery [35]. There was also an earlier set of guidelines of Society for Vascular Nursing (SVN) Task Force published by Smith et al. [36]. This covers mostly the nursing and patient care aspects of pre-operative, intraoperative and post-operative stages. The guidelines use evidence-based best practice approach. A set of guidelines for peripheral arterial disease was published by Hirsch et al. on behalf of ACC/AHA (American College of Cardiology/American Heart

Association) and collaborated by many other related organizations. This contains information on classification of levels of evidence and standards of their acceptance. The diseases included are lower extremity, renal, mesenteric and abdominal aortic aneurysms [37].

The American College of Radiology (ACR) has also published appropriateness criteria for AAA interventional planning and follow-up [43, 44]. It contains rating for appropriateness for planning pre-endovascular repair or open repair and for follow-up after these repairs with a note by experts. Best practice guidelines on clinical decision support systems have been published by the ACR and Radiology Business Management Association (RBMA) jointly. This contains evidence-based best practices related to all heath-care service components aimed at best patient outcomes. Other ACR guidelines are on the development of evidence tables for diagnostic studies, literature search process, non-traumatic aortic disease, procedure information like contrast used and PET and topic review process. All these appropriateness criteria (as they are called) follow a standard format containing explanatory notes by experts. Recently a study was conducted [41] in Sweden, to estimate the effect of AAA screening on disease-specific mortality, incidence and surgery. It was found that AAA mortality in Swedish men has decreased from 36 to 10 deaths per 100,000 men aged 65–74 years between the early 2000s and 2015. Mortality decreased at similar rates in all Swedish counties, irrespective of whether AAA screening was offered. It was mentioned that AAA screening in Sweden did not contribute substantially to the large observed reductions in AAA mortality and such reductions were mostly caused by other factors, probably

*Challenges for Intelligent Data Analysis Methods in Medical Image Analysis during Surgical…*

The National Guideline Clearinghouse is a database for evidence-based clinical practice guidelines prepared by various organizations for comparison, synthesizes guidelines prepared by different agencies on the same topic for similarities and differences and serves as an electronic platform for exchanging information on such guidelines and is also a source of annotated bibliography database. Two of these deal

**2.3 Hospital compliance of ACR guideline on abdominal aortic aneurysm**

Huber et al. collected NIS data for 1994–1996 [43]. Most patients were white males. Majority of repairs were done at large, urban and non-teaching hospitals. The hospital mortality rate was 4.2%. There was 32.4% incidence of complications. Home discharge rate was 91.2%. Bad outcome was experienced in 12.6%. Bad outcome was related to age, gender, complications and comorbidities (patient classifications) and hospital size and year of procedure. The authors concluded that outcome after open repair of intact AAA in US was good. However, only white males visiting the hospitals and procedures done only at large, urban non-teaching hospitals show skewed behaviour of AAA detection and treatment. There may be a certain degree of not falling in line with ACR guidelines in some respects. However, this is not clear from the results as only short-term data were selected and the

The extent of compliance with long-term surveillance recommendations following EVAR and type B aortic dissection was found poor due to lack of coordinated approach. Cases of 204 patients (171 EVAR, 33 type B dissection) were evaluated. Of 171 EVAR, 100 were AAA, 45 TA, 12 TAA and 7 iliac artery and 7 proximal graft extensions. Medium follow-up period was 28 10.5 months. Overall, 56% were lost to follow-up, and 11% never returned after initial hospitalization [44]. Lakhani et al. reported an increase in nonroutine radiological communications especially of critical finings in a tertiary hospital during 1997–2005 due to increasing compliance with ACR guidelines [45]. According to Benjamin et al. [46], compliance of the radiologist with hospital guidelines for nonroutine communication of diagnostic imaging results gave better outcomes in a general hospital. Such communications

reduced smoking.

with cardiovascular diseases [42].

*DOI: http://dx.doi.org/10.5772/intechopen.86711*

methods used were unable to detect this.

**31**

were required most for CT, followed by MRI and ultrasound.

The American College of Cardiology Foundation (ACCF) and American Heart Association (AHA) jointly published a set of guidelines for diagnosis and management of patients with TA [38]. This contains the following:


Several guidelines are being published by a variety of organizations within countries internationally. It is appropriate to evaluate these guidelines with respect to their usefulness in routine clinical practices. Ferket et al. in 2012 reviewed the guidelines published on screening for AAA during 2003–2010. Of 2415 titles, 7 were included in this study. These were USPSTF2005, ACC2005, NSC2007, CSVS2007, CCS2005, SVS1 of 2004, and SVS2 of 2009 [39]. Unfortunately, some of the more recent ones discussed above were not included. Some changes in the classification systems of ICD in different years could also affect evaluation.

There was consensus across the guidelines regarding one-time screening of elderly men to detect and treat aneurysms of larger than 5.5 cm in size. For smaller aneurysms and other target groups, prediction models and effectiveness analysis are needed.

The American Image Management (AIM) guidelines on diagnostic imaging, known as AIM, 2010, contain imaging protocols for various parts of the body using CT, MRI, PET, CTA, MRA and other imaging methods including proton beam treatment. These have also been published in parts as updated versions later in 2014 [40].

#### *Challenges for Intelligent Data Analysis Methods in Medical Image Analysis during Surgical… DOI: http://dx.doi.org/10.5772/intechopen.86711*

The American College of Radiology (ACR) has also published appropriateness criteria for AAA interventional planning and follow-up [43, 44]. It contains rating for appropriateness for planning pre-endovascular repair or open repair and for follow-up after these repairs with a note by experts. Best practice guidelines on clinical decision support systems have been published by the ACR and Radiology Business Management Association (RBMA) jointly. This contains evidence-based best practices related to all heath-care service components aimed at best patient outcomes. Other ACR guidelines are on the development of evidence tables for diagnostic studies, literature search process, non-traumatic aortic disease, procedure information like contrast used and PET and topic review process. All these appropriateness criteria (as they are called) follow a standard format containing explanatory notes by experts. Recently a study was conducted [41] in Sweden, to estimate the effect of AAA screening on disease-specific mortality, incidence and surgery. It was found that AAA mortality in Swedish men has decreased from 36 to 10 deaths per 100,000 men aged 65–74 years between the early 2000s and 2015. Mortality decreased at similar rates in all Swedish counties, irrespective of whether AAA screening was offered. It was mentioned that AAA screening in Sweden did not contribute substantially to the large observed reductions in AAA mortality and such reductions were mostly caused by other factors, probably reduced smoking.

The National Guideline Clearinghouse is a database for evidence-based clinical practice guidelines prepared by various organizations for comparison, synthesizes guidelines prepared by different agencies on the same topic for similarities and differences and serves as an electronic platform for exchanging information on such guidelines and is also a source of annotated bibliography database. Two of these deal with cardiovascular diseases [42].

#### **2.3 Hospital compliance of ACR guideline on abdominal aortic aneurysm**

Huber et al. collected NIS data for 1994–1996 [43]. Most patients were white males. Majority of repairs were done at large, urban and non-teaching hospitals. The hospital mortality rate was 4.2%. There was 32.4% incidence of complications. Home discharge rate was 91.2%. Bad outcome was experienced in 12.6%. Bad outcome was related to age, gender, complications and comorbidities (patient classifications) and hospital size and year of procedure. The authors concluded that outcome after open repair of intact AAA in US was good. However, only white males visiting the hospitals and procedures done only at large, urban non-teaching hospitals show skewed behaviour of AAA detection and treatment. There may be a certain degree of not falling in line with ACR guidelines in some respects. However, this is not clear from the results as only short-term data were selected and the methods used were unable to detect this.

The extent of compliance with long-term surveillance recommendations following EVAR and type B aortic dissection was found poor due to lack of coordinated approach. Cases of 204 patients (171 EVAR, 33 type B dissection) were evaluated. Of 171 EVAR, 100 were AAA, 45 TA, 12 TAA and 7 iliac artery and 7 proximal graft extensions. Medium follow-up period was 28 10.5 months. Overall, 56% were lost to follow-up, and 11% never returned after initial hospitalization [44]. Lakhani et al. reported an increase in nonroutine radiological communications especially of critical finings in a tertiary hospital during 1997–2005 due to increasing compliance with ACR guidelines [45]. According to Benjamin et al. [46], compliance of the radiologist with hospital guidelines for nonroutine communication of diagnostic imaging results gave better outcomes in a general hospital. Such communications were required most for CT, followed by MRI and ultrasound.

Association) and collaborated by many other related organizations. This contains information on classification of levels of evidence and standards of their acceptance. The diseases included are lower extremity, renal, mesenteric and abdominal aortic

The American College of Cardiology Foundation (ACCF) and American Heart Association (AHA) jointly published a set of guidelines for diagnosis and

1.Recommendations for imaging and detection/identification/evaluation of genetic syndromes, familial TA and dissections and bicuspid aortic valve and

3.Initial evaluation and management of acute thoracic aortic disease.

4.Surgical intervention for acute thoracic aortic dissection and intramural

6.Medical treatment of patients with thoracic aortic diseases, asymptomatic patients with ascending aortic aneurysm and symptomatic patients with TA.

8.Counselling and management of chronic aortic diseases in pregnancy, aortic

10.Surveillance of thoracic aortic disease and previously repaired patients and employment and lifestyle in patients with thoracic aortic disease.

Several guidelines are being published by a variety of organizations within countries internationally. It is appropriate to evaluate these guidelines with respect to their usefulness in routine clinical practices. Ferket et al. in 2012 reviewed the guidelines published on screening for AAA during 2003–2010. Of 2415 titles, 7 were included in this study. These were USPSTF2005, ACC2005, NSC2007, CSVS2007, CCS2005, SVS1 of 2004, and SVS2 of 2009 [39]. Unfortunately, some of the more recent ones discussed above were not included. Some changes in the classification

There was consensus across the guidelines regarding one-time screening of elderly men to detect and treat aneurysms of larger than 5.5 cm in size. For smaller aneurysms and other target groups, prediction models and effectiveness analysis are

The American Image Management (AIM) guidelines on diagnostic imaging, known as AIM, 2010, contain imaging protocols for various parts of the body using CT, MRI, PET, CTA, MRA and other imaging methods including proton beam treatment. These have also been published in parts as updated versions later

7.Open surgery for ascending aortic aneurysm, aortic arch aneurysms, descending thoracic aorta and thoracicoabdominal aortic aneurysm.

arch and thoracic aortic atheroma and athero-embolic diseases.

management of patients with TA [38]. This contains the following:

2.Estimation of pretest risk of thoracic aortic dissection.

hematoma without intimal defect and history.

5.Physical examination of thoracic aortic disease.

9.Periprocedural and perioperative management.

systems of ICD in different years could also affect evaluation.

associated congenital variants in adults.

aneurysms [37].

*Aortic Aneurysm and Aortic Dissection*

needed.

in 2014 [40].

**30**

Good correlation was found by Gilk et al., [47] between 2013 updated ACR guidelines on MR safe practices and the Joint Commission's Sentinel Event Alert No 39 on MR safety as the Environment of Care standards. About 90% of US academic emergency departments deviated from ACR guidelines on contrast practices for abdominal and pelvic CT imaging, as observed by [48]. According to Abramson et al., there are wide variations with respect to compliance on ACR guidelines by different hospitals [49]. Some reports on compliance of hospitals with ACR guidelines on fluoroscopy and CT were cited and discussed [50]. Quality assurance protocols, tracking exposure time and direct measurement of patient exposure time all based on ACR guidelines have improved compliance in reducing radiation exposure in some hospitals.

Besides these reports on some factors related to compliance of hospitals with ACR guidelines, many individual hospitals have reported receiving awards and certificates of ACR imaging compliance.

In general, there are no direct studies on the effect of extent of ACR compliance on aneurysm deaths. The findings discussed above only indicate the lack of compliance on certain aspects of ACR guidelines but nothing to connect them with aneurysm mortality. The importance of this study is evident from this research gap.

and may lead to in-hospital mortality in spite of the best treatment given as it may be too late for any intervention to be successful. Urgent also is almost equally critical which accounted for about 17% of admissions. Emergency and urgent

*Imaging frequencies using different methods of aortic aneurysm patients admitted in US hospitals.*

Total 466 89 3819 28,060 32,434 <0.0001

**Hospital contexts Medical imaging procedures Total P**

*Challenges for Intelligent Data Analysis Methods in Medical Image Analysis during Surgical…*

Admission type Emergency 340 59 1084 9319 10,802

*DOI: http://dx.doi.org/10.5772/intechopen.86711*

**CT MRI US DSA**

Urgent 53 10 469 5244 5776 Elective 73 20 2263 13,478 15,834 Trauma centre 0 0 2 19 21 Other 0 0 1 0 1

Different imaging methods may be used for different admission types. Thus more than 90% imaging was done with DSA in the case of emergency and urgent admissions compared to only about 79% for elective admissions (**Table 3**). Contrary to what was theorized, emergency plus urgent and elective admissions recorded almost equal 40–42% proportion of total patients for all imaging modalities. Overall, highest frequency (13,478) was observed for DSA in the case of elective admissions, and the lowest frequency of 10 was recorded by MRI for urgent admissions. On the other hand, US was highest in elective followed by emergency admissions. CT and MRI were highest in emergency followed by urgent admissions. Trauma centre and other admission types recorded very low frequencies to make any significant impact. Thus irrespective of admission type, DSA is the choice method

This question is answered by reviewing research works in which two or more imaging methods are compared for their efficiency and effectiveness of aneurysm diagnosis, in which some specific aspect of the algorithms of one or more is enhanced. Several scientists have compared different imaging methods for diagnosis of aneurysms in which some algorithmic enhancements and support systems have been made for increasing their effectiveness and efficiencies of diagnosis. The parameters for efficiency are accuracy of diagnosis either by experimental comparisons of image readers or by relative quantitative or qualitative assessments. The measure of effectiveness is the relative merits of diagnosing some specific charac-

This study utilized a series of processing methods on the NIS data, data mining techniques and statistical procedures to attain its goals. Data cleaning, recoding and extraction were used to arrange the raw data for the analysis. Statistical analyses such as frequencies, correlation, chi-square analysis, logistic regression and multinominal logistic test were applied. All of these different methodologies were used to analyse and process a big data set derived from multiple years from 2008 to 2012 and geographically collected from more than 4300 hospitals across the USA.

The NIS data set on different variables covering the period of 2008–2012 were used in this project. The variables required to fulfill different objectives are as given

teristics of the aneurysm under study like location, size, anatomy, etc.

**2.5 Objectives, variables and statistical analysis procedures**

together constitute about 51% against 48.8% of elective admissions.

followed by US.

**Table 3.**

in **Table 4**.

**33**

#### **2.4 Frequencies of aneurysm diagnostic imaging by different modalities**

Aneurysm is a chronic disease usually affecting people towards the end of their lives. This makes detection and intervention procedures highly risky. A majority of aneurysm patients do not report to the hospitals. Among those reported, repair procedure is not done on a good majority. It is notable that imaging helps proper diagnosis eventually leading to the reduction of mortality. Abdominal aortic aneurysm is most common with roughly 73% accounted, followed by thoracic aortic aneurysm. All others occur in very low frequencies compared to these. Although EVAR is promising, OAR is still the choice method, probably as the best method to deal with emergency and urgent admissions of ruptured aneurysms. In spite of other more promising methods becoming increasingly available, DSA is still the gold standard for diagnostic imaging. Such techniques like MRI and CT were used very rarely.

The data related to different types of aortic aneurysm admissions in US hospitals are given in **Figure 2**.

Out of a total number of 32,434 cases, elective admission dominated with 48.8% of valid data, followed by about 33.3% for emergency admissions. The latter is alarming as emergency admissions are usually associated with ruptured aneurysms

**Figure 2.**

*Admission type of aortic aneurysm patients in US hospitals.*


*Challenges for Intelligent Data Analysis Methods in Medical Image Analysis during Surgical… DOI: http://dx.doi.org/10.5772/intechopen.86711*

#### **Table 3.**

Good correlation was found by Gilk et al., [47] between 2013 updated ACR guidelines on MR safe practices and the Joint Commission's Sentinel Event Alert No 39 on MR safety as the Environment of Care standards. About 90% of US academic emergency departments deviated from ACR guidelines on contrast practices for abdominal and pelvic CT imaging, as observed by [48]. According to Abramson et al., there are wide variations with respect to compliance on ACR guidelines by different hospitals [49]. Some reports on compliance of hospitals with ACR guidelines on fluoroscopy and CT were cited and discussed [50]. Quality assurance protocols, tracking exposure time and direct measurement of patient exposure time all based on ACR guidelines have improved compliance in reducing radiation exposure

Besides these reports on some factors related to compliance of hospitals with ACR guidelines, many individual hospitals have reported receiving awards and

**2.4 Frequencies of aneurysm diagnostic imaging by different modalities**

In general, there are no direct studies on the effect of extent of ACR compliance on aneurysm deaths. The findings discussed above only indicate the lack of compliance on certain aspects of ACR guidelines but nothing to connect them with aneurysm mortality. The importance of this study is evident from this research gap.

Aneurysm is a chronic disease usually affecting people towards the end of their lives. This makes detection and intervention procedures highly risky. A majority of aneurysm patients do not report to the hospitals. Among those reported, repair procedure is not done on a good majority. It is notable that imaging helps proper diagnosis eventually leading to the reduction of mortality. Abdominal aortic aneurysm is most common with roughly 73% accounted, followed by thoracic aortic aneurysm. All others occur in very low frequencies compared to these. Although EVAR is promising, OAR is still the choice method, probably as the best method to deal with emergency and urgent admissions of ruptured aneurysms. In spite of other more promising methods becoming increasingly available, DSA is still the gold standard for diagnostic imaging. Such techniques like MRI and CT were used

The data related to different types of aortic aneurysm admissions in US hospitals

Out of a total number of 32,434 cases, elective admission dominated with 48.8%

of valid data, followed by about 33.3% for emergency admissions. The latter is alarming as emergency admissions are usually associated with ruptured aneurysms

in some hospitals.

very rarely.

**Figure 2.**

**32**

*Admission type of aortic aneurysm patients in US hospitals.*

are given in **Figure 2**.

certificates of ACR imaging compliance.

*Aortic Aneurysm and Aortic Dissection*

*Imaging frequencies using different methods of aortic aneurysm patients admitted in US hospitals.*

and may lead to in-hospital mortality in spite of the best treatment given as it may be too late for any intervention to be successful. Urgent also is almost equally critical which accounted for about 17% of admissions. Emergency and urgent together constitute about 51% against 48.8% of elective admissions.

Different imaging methods may be used for different admission types. Thus more than 90% imaging was done with DSA in the case of emergency and urgent admissions compared to only about 79% for elective admissions (**Table 3**). Contrary to what was theorized, emergency plus urgent and elective admissions recorded almost equal 40–42% proportion of total patients for all imaging modalities. Overall, highest frequency (13,478) was observed for DSA in the case of elective admissions, and the lowest frequency of 10 was recorded by MRI for urgent admissions. On the other hand, US was highest in elective followed by emergency admissions. CT and MRI were highest in emergency followed by urgent admissions. Trauma centre and other admission types recorded very low frequencies to make any significant impact. Thus irrespective of admission type, DSA is the choice method followed by US.

This question is answered by reviewing research works in which two or more imaging methods are compared for their efficiency and effectiveness of aneurysm diagnosis, in which some specific aspect of the algorithms of one or more is enhanced. Several scientists have compared different imaging methods for diagnosis of aneurysms in which some algorithmic enhancements and support systems have been made for increasing their effectiveness and efficiencies of diagnosis. The parameters for efficiency are accuracy of diagnosis either by experimental comparisons of image readers or by relative quantitative or qualitative assessments. The measure of effectiveness is the relative merits of diagnosing some specific characteristics of the aneurysm under study like location, size, anatomy, etc.

This study utilized a series of processing methods on the NIS data, data mining techniques and statistical procedures to attain its goals. Data cleaning, recoding and extraction were used to arrange the raw data for the analysis. Statistical analyses such as frequencies, correlation, chi-square analysis, logistic regression and multinominal logistic test were applied. All of these different methodologies were used to analyse and process a big data set derived from multiple years from 2008 to 2012 and geographically collected from more than 4300 hospitals across the USA.

#### **2.5 Objectives, variables and statistical analysis procedures**

The NIS data set on different variables covering the period of 2008–2012 were used in this project. The variables required to fulfill different objectives are as given in **Table 4**.


classifications include age, gender, race, insurance type, admission type as source

LOS Length of stay Ratio Length of stay from 0 day as same-day stays

geographical region are available. This is the core NIS file on hospital.

YEAR Year Ratio Calendar year (2008–2012)

**Variable in the study Type Description**

*Challenges for Intelligent Data Analysis Methods in Medical Image Analysis during Surgical…*

DXCCSn Comorbidities Nominal Clinical classification software

DIED In-hospital mortality Ordinal Died during hospitalization

FEMALE Gender Nominal The sex of the patient (male or female) RACE Race Nominal The race and ethnicity of patient PAY1 Insurance type Nominal Indicates the expected primary payer SOURCE Admission type Nominal Source of admission to point of origin for

Nominal ICD-9 procedure codes

groups

admission or visit

to greater than 365 days

Ordinal Age in group at admission from 1 to 21 age

DXn Aortic aneurysm diagnosis Nominal ICD-9 diagnosis codes

In the hospital file in **Table 6**, information on location and type, bed size and

Results of a recent research by the authors are discussed here. ACR has nine rating scales of appropriateness criteria for different imaging methods and aneurysm types. For convenience of application for any imaging method and aneurysm type in our study, these were reduced to three appropriateness criteria by combining the same rating of different imaging methods and aneurysm types and making the ratings clearer. Hospital-wise data from NIS on mortality status (died/not died) to evaluate the effect of ACR compliance level on reducing mortality rate. The results showed that increasing levels of ACR compliance reduced mortality rates. More systematic research may be required for confirming the results. ACR appropriateness guidelines for diagnostic imaging have been developed by a large team of experts who examined available research works for the quality of evidence to prescribe these guidelines. The guidelines are reviewed and updated when new evidence becomes available. Hence, there is enough logic in contending that

**Type Description**

Ordinal Hospital bed size

Nominal Hospital's location and teaching status

Annual Survey of Hospitals

Nominal The hospital's census region was obtained from the AHA

and the calendar year to which the data pertains.

**Core file element**

**Table 5.**

*The core file data element format.*

**Hospital file element**

**Table 6.**

**35**

H-LOCTCH Hospital

HOSP\_REGION Hospital

*Data elements in NIS hospital files.*

H-BEDSZ Hospital bed size

**Variable in the study**

location

region

PRn Interventional repair and imaging procedures

*DOI: http://dx.doi.org/10.5772/intechopen.86711*

AGE Age group based on WHO standardization

#### **Table 4.**

*Relationship of objectives and statistical analysis procedures.*

#### *2.5.1 Data availability*

Availability of the required data is a major factor in the ability to perform the above tests. In this project, all the required data are to be sourced from NIS data set. Hospitals may have not have given the cause of death properly. They may have automatically assumed that aneurysm patients died due to aneurysm only. Aneurysm as the specific cause of death may be absent. Even if it is possible to get data on a number of patients who underwent different repair procedures, records may not allow classification of repair procedures versus death data. A similar problem may arise with respect to imaging procedures also. Compliance percentage may not be indicative of a specific influence of ACR unless it is very high. At medium or low percentage values, the specific parameters on which there is compliance may also be important. Thus, the type of data available in NIS data set and its relationship with ACR guidelines is important. These are described below.

#### *2.5.2 NIS dataset*

There are two parts: the core file and the hospital file.

The core file has the data elements depicted in **Table 5**. The first core element of DXn and PRn deals with ICD-9 diagnostic and repair procedural codes, respectively. Other elements relate to mortality and patient classifications. The patient

*Challenges for Intelligent Data Analysis Methods in Medical Image Analysis during Surgical… DOI: http://dx.doi.org/10.5772/intechopen.86711*


#### **Table 5.**

*2.5.1 Data availability*

**Table 4.**

*2.5.2 NIS dataset*

**34**

Availability of the required data is a major factor in the ability to perform the above tests. In this project, all the required data are to be sourced from NIS data set. Hospitals may have not have given the cause of death properly. They may have automatically assumed that aneurysm patients died due to aneurysm only. Aneurysm as the specific cause of death may be absent. Even if it is possible to get data on a number of patients who underwent different repair procedures, records may not allow classification of repair procedures versus death data. A similar problem may arise with respect to imaging procedures also. Compliance percentage may not be indicative of a specific influence of ACR unless it is very high. At medium or low percentage values, the specific parameters on which there is compliance may also be important. Thus, the type of data available in NIS data set and its relationship with

**No Objective Statistical tests**

1 To study the relation between imaging modalities and in-hospital mortality

2 To compare in-hospital mortality of EVAR with OAR when different

3 To evaluate the effect of using ACR recommended imaging methods and

4 To determine among different patient characteristics and hospital context, those factors which can be used for prediction and thereby reduction of in-

5 To determine among significant predictor factors, which type of diagnostic

imaging performed is associated with in-hospital mortality

among aortic aneurysm patients through US hospitals

*Aortic Aneurysm and Aortic Dissection*

diagnostic imaging techniques are used in both cases

extent of compliance on in-hospital mortality

hospital mortality to desired levels

*Relationship of objectives and statistical analysis procedures.*

**applied**

Pearson chi-square test McNemar's test ANOVA test Logistic regression test

Pearson chi-square test McNemar's test ANOVA test Logistic regression test

Pearson chi-square test Gamma correlation test Logistic regression test

Logistic regression test

Multinominal logistic test

The core file has the data elements depicted in **Table 5**. The first core element of

DXn and PRn deals with ICD-9 diagnostic and repair procedural codes, respectively. Other elements relate to mortality and patient classifications. The patient

ACR guidelines is important. These are described below.

There are two parts: the core file and the hospital file.

*The core file data element format.*

classifications include age, gender, race, insurance type, admission type as source and the calendar year to which the data pertains.

In the hospital file in **Table 6**, information on location and type, bed size and geographical region are available. This is the core NIS file on hospital.

Results of a recent research by the authors are discussed here. ACR has nine rating scales of appropriateness criteria for different imaging methods and aneurysm types. For convenience of application for any imaging method and aneurysm type in our study, these were reduced to three appropriateness criteria by combining the same rating of different imaging methods and aneurysm types and making the ratings clearer. Hospital-wise data from NIS on mortality status (died/not died) to evaluate the effect of ACR compliance level on reducing mortality rate. The results showed that increasing levels of ACR compliance reduced mortality rates. More systematic research may be required for confirming the results. ACR appropriateness guidelines for diagnostic imaging have been developed by a large team of experts who examined available research works for the quality of evidence to prescribe these guidelines. The guidelines are reviewed and updated when new evidence becomes available. Hence, there is enough logic in contending that


#### **Table 6.** *Data elements in NIS hospital files.*

compliance with ACR guidelines will improve the patient outcome especially on reducing mortality rate.

The details of the methodology and results are given and are discussed with the support of scientific evidence.
