Advanced risk prediction for aortic dissection patients using imaging-based computational flow analysis

Patients with either a repaired or medically managed aortic dissection have varying degrees of risk of developing late complications. High-risk patients would benefit from earlier intervention to improve their long-term survival. Currently serial imaging is used for risk stratification, which is not always reliable. On the other hand, understanding aortic haemodynamics within a dissection is essential to fully evaluate the disease and predict how it may progress. In recent decades, computational fluid dynamics (CFD) has been extensively applied to simulate complex haemodynamics within aortic diseases, and more recently, four-dimensional (4D)-flow magnetic resonance imaging (MRI) techniques have been developed for in vivo haemodynamic measurement. This paper presents a comprehensive review on the application of image-based CFD simulations and 4D-flow MRI analysis for risk prediction in aortic dissection. The key steps involved in patient-specific CFD analyses are demonstrated. Finally, we propose a workflow incorporating computational modelling for personalised assessment to aid in risk stratification and treatment decision-making.

Bioprosthetic valve thrombosis and degeneration following transcatheter aortic valve implantation (TAVI)

Bioprosthetic valve thrombosis (BPVT) is a recognised complication of prosthetic aortic valves and can be found in up to 13% of patients after transcatheter implantation. The mechanism of BPVT is not well known, abnormal flow conditions in the new and native sinuses and lack of functional endothelialisation are suspected causes. BPVT may result in valve dysfunction, possibly related to degeneration, and recurrence of patient symptoms, or remain subclinical. BPVT is best diagnosed at multiphase gated computed tomography (CT) angiography as the presence of reduced leaflet motion (RELM) and hypoattenuating aortic leaflet thickening (HALT). Although CT is used to exclude BPVT in symptomatic patients and those with increased valve gradients, the value of screening and prophylactic anticoagulation is debatable.

Imaging of transcatheter aortic valve replacement complications

Aortic stenosis is increasing in incidence and is now commonly managed with transcatheter aortic valve replacement (TAVR) in intermediate and high-risk patients. Radiologists are likely to encounter patients undergoing this procedure both pre- and postoperatively, and therefore, an understanding of procedural complications is essential. Complications may relate to the access site or approach, or the valve itself. This article will review the most common complications described in literature and focuses on the role of multidetector computed tomography (CT) in their evaluation either exclusively, or complementary to other imaging methods.

Multimodality quantitative assessments of myocardial perfusion using dynamic contrast enhanced magnetic resonance and 15O-labelled water positron emission tomography imaging

Kinetic modelling of myocardial perfusion imaging data allows the absolute quantification of myocardial blood flow (MBF) and can improve the diagnosis and clinical assessment of coronary artery disease (CAD). Positron emission tomography (PET) imaging is considered the reference standard technique for absolute quantification, whilst oxygen-15 (¹⁵O)-water has been extensively implemented for MBF quantification. Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) has also been used for MBF quantification and showed comparable diagnostic performance against (¹⁵O)-water PET studies. We investigated for the first time the diagnostic performance of two different PET MBF analysis softwares PMOD and Carimas, for obstructive CAD detection against invasive clinical standard methods in 20 patients with known or suspected CAD. Fermi and distributed parameter modelling-derived MBF quantification from DCE-MRI was also compared against (¹⁵O)-water PET, in a subgroup of 6 patients. The sensitivity and specificity for PMOD was significantly superior for obstructive CAD detection in both per vessel (0.83, 0.90) and per patient (0.86, 0.75) analysis, against Carimas (0.75, 0.65), (0.81, 0.70), respectively. We showed strong, significant correlations between MR and PET MBF quantifications (r=0.83-0.92). However, DP and PMOD analysis demonstrated comparable and higher haemodynamic differences between obstructive versus (no, minor or non)-obstructive CAD, against Fermi and Carimas analysis. Our MR method assessments against the optimum PET reference standard technique for perfusion analysis showed promising results in per segment level and can support further multi-modality assessments in larger patient cohorts. Further MR against PET assessments may help to determine their comparative diagnostic performance for obstructive CAD detection.

Assessment of myocardial fibrosis with T1 mapping MRI

Myocardial fibrosis can arise from a range of pathological processes and its presence correlates with adverse clinical outcomes. Cardiac magnetic resonance (CMR) can provide a non-invasive assessment of cardiac structure, function, and tissue characteristics, which includes late gadolinium enhancement (LGE) techniques to identify focal irreversible replacement fibrosis with a high degree of accuracy and reproducibility. Importantly the presence of LGE is consistently associated with adverse outcomes in a range of common cardiac conditions; however, LGE techniques are qualitative and unable to detect diffuse myocardial fibrosis, which is an earlier form of fibrosis preceding replacement fibrosis that may be reversible. Novel T1 mapping techniques allow quantitative CMR assessment of diffuse myocardial fibrosis with the two most common measures being native T1 and extracellular volume (ECV) fraction. Native T1 differentiates normal from infarcted myocardium, is abnormal in hypertrophic cardiomyopathy, and may be particularly useful in the diagnosis of Anderson-Fabry disease and amyloidosis. ECV is a surrogate measure of the extracellular space and is equivalent to the myocardial volume of distribution of the gadolinium-based contrast medium. It is reproducible and correlates well with fibrosis on histology. ECV is abnormal in patients with cardiac failure and aortic stenosis, and is associated with functional impairment in these groups. T1 mapping techniques promise to allow earlier detection of disease, monitor disease progression, and inform prognosis; however, limitations remain. In particular, reference ranges are lacking for T1 mapping values as these are influenced by specific CMR techniques and magnetic field strength. In addition, there is significant overlap between T1 mapping values in healthy controls and most disease states, particularly using native T1, limiting the clinical application of these techniques at present.

Perioperative elafin for ischaemia-reperfusion injury during coronary artery bypass graft surgery: a randomised-controlled trial

Background

Elafin is a potent endogenous neutrophil elastase inhibitor that protects against myocardial inflammation and injury in preclinical models of ischaemic-reperfusion injury. We investigated whether elafin could inhibit myocardial ischaemia-reperfusion injury induced during coronary artery bypass graft (CABG) surgery.

Methods and results

In a randomised double-blind placebo-controlled parallel group clinical trial, 87 patients undergoing CABG surgery were randomised 1:1 to intravenous elafin 200 mg or saline placebo administered after induction of anaesthesia and prior to sternotomy. Myocardial injury was measured as cardiac troponin I release over 48 h (area under the curve (AUC)) and myocardial infarction identified with MRI. Postischaemic inflammation was measured by plasma markers including AUC high-sensitive C reactive protein (hs-CRP) and myeloperoxidase (MPO). Elafin infusion was safe and resulted in >3000-fold increase in plasma elafin concentrations and >50% inhibition of elastase activity in the first 24 h. This did not reduce myocardial injury over 48 h (ratio of geometric means (elafin/placebo) of AUC troponin I 0.74 (95% CI 0.47 to 1.15, p=0.18)) although post hoc analysis of the high-sensitive assay revealed lower troponin I concentrations at 6 h in elafin-treated patients (median 2.4 vs 4.1 μg/L, p=0.035). Elafin had no effect on myocardial infarction (elafin, 7/34 vs placebo, 5/35 patients) or on markers of inflammation: mean differences for AUC hs-CRP of 499 mg/L/48 h (95% CI −207 to 1205, p=0.16), and AUC MPO of 238 ng/mL/48 h (95% CI −235 to 711, p=0.320).

Conclusions

There was no strong evidence that neutrophil elastase inhibition with a single-dose elafin treatment reduced myocardial injury and inflammation following CABG-induced ischaemia-reperfusion injury.

Trial registration number

(EudraCT 2010-019527-58, ISRCTN82061264).

Imaging of cardiovascular risk in patients with Turner's syndrome

Turner's syndrome is a disorder defined by an absent or structurally abnormal second X chromosome and affects around 1 in 2000 newborn females. The standardised mortality ratio in Turner's syndrome is around three-times higher than in the general female population, mainly as a result of cardiovascular disorders. Most striking is the early age at which Turner's syndrome patients develop the life-threatening complications of cardiovascular disorders compared to the general population. The cardiovascular risk stratification in Turner's syndrome is challenging and imaging is not systematically used. The aim of this article is to review cardiovascular risks in this group of patients and discuss a systematic imaging approach for early identification of cardiovascular disorders in these patients.

Iterative reconstruction and individualized automatic tube current selection reduce radiation dose while maintaining image quality in 320-multidetector computed tomography coronary angiography

AIM

To assess the effect of two iterative reconstruction algorithms (AIDR and AIDR3D) and individualized automatic tube current selection on radiation dose and image quality in computed tomography coronary angiography (CTCA).

MATERIALS AND METHODS

In a single-centre cohort study, 942 patients underwent electrocardiogram-gated CTCA using a 320-multidetector CT system. Images from group 1 (n = 228) were reconstructed with a filtered back projection algorithm (Quantum Denoising Software, QDS+). Iterative reconstruction was used for group 2 (AIDR, n = 379) and group 3 (AIDR3D, n = 335). Tube current was selected based on body mass index (BMI) for groups 1 and 2, and selected automatically based on scout image attenuation for group 3. Subjective image quality was graded on a four-point scale (1 = excellent, 4 = non-diagnostic).

RESULTS

There were no differences in age (p = 0.975), body mass index (p = 0.435), or heart rate (p = 0.746) between the groups. Image quality improved with iterative reconstruction and automatic tube current selection [1.3 (95% confidence intervals (CI): 1.2-1.4), 1.2 (1.1-1.2) and 1.1 (1-1.2) respectively; p < 0.001] and radiation dose decreased [274 (260-290), 242 (230-253) and 168 (156-180) mGy cm, respectively; p < 0.001].

CONCLUSION

The application of the latest iterative reconstruction algorithm and individualized automatic tube current selection can substantially reduce radiation dose whilst improving image quality in CTCA.

Embolization for non-variceal upper gastrointestinal tract haemorrhage: a systematic review

AIM

To assess the published evidence on the endovascular treatment of non-variceal upper gastrointestinal haemorrhage.

MATERIALS AND METHODS

An Ovid Medline search of published literature was performed (1966-2009). Non-English literature, experimental studies, variceal haemorrhage and case series with fewer than five patients were excluded. The search yielded 1888 abstracts. Thirty-five articles were selected for final analysis.

RESULTS

The total number of pooled patients was 927. The technical and clinical success of embolization ranged from 52-100% and 44-100%, respectively. The pooled mean technical/clinical success rate in primary upper gastrointestinal tract haemorrhage (PUGITH) only, trans-papillary haemorrhage (TPH) only, and mixed studies were 84%/67%, 93%/89%, and 93%/64%, respectively. Clinical outcome was adversely affected by multi-organ failure, shock, corticosteroids, transfusion, and coagulopathy. The anatomical source of haemorrhage and procedural variables did not affect the outcome. A successful embolization improved survival by 13.3 times. Retrospective comparison with surgery demonstrated equivalent mortality and clinical success, despite embolization being applied to a more elderly population with a higher prevalence of co-morbidities.

CONCLUSIONS

Embolization is effective in this very difficult cohort of patients with outcomes similar to surgery.

Epididymo-orchitis risk factors in traumatic spinal cord injured patients

STUDY DESIGN

Retrospective audit and interview-based study of a traumatic spinal cord injured cohort, assessing the incidence and risk of epididymo-orchitis (E-O).

OBJECTIVES

Assess the potential risk factors for E-O in this cohort (spinal cord injured patients).

SETTING

Janbazan Clinic for Spinal Cord Injuries, Mashad, Iran.

METHODS

A retrospective notes audit of 169 male traumatic spinal cord injured (SCI) patients was performed. In addition, interviews were performed to confirm any equivocal data. The following risk factors were assessed: history of recurrent urinary tract infections (UTIs), urethral stricture, urethral diverticuli, urinary fistula, urinary calculi, spinal injury type, neurogenic bladder type, autonomic dysreflexia, vesico-ureteral reflux, sphincterotomy, vasectomy, marriage status, bladder residual and emptying method, ejaculation, spinal injury level, micturation control, and muscular spasm, which included detrusor, external sphincter or lower limb spasm.

RESULTS

A total of 65 patients from our group (38.5%) had suffered E-O at least once. E-O presented on average, 3.9 years after the SCI. Patients with a history of muscular spasm appeared less likely to develop E-O (P<0.05). None of the vasectomised patients developed E-O. The relation between all the other factors and E-O were not significant.

CONCLUSIONS

Our study has shown that the presence of muscular spasm decreases the risk of E-O, although the mechanism remains unclear. Surprisingly, the other historical risk factors showed no clear relation with E-O occurrence.

The patient's dilemma: prostate cancer treatment choices

PURPOSE

We summarize the literature addressing factors that influence treatment decisions made by men with prostate cancer.

MATERIALS AND METHODS

A MEDLINE search of the English language literature published between 1969 and 2000, using the combined MESH key words "prostatic neoplasms," "patient participation," "Internet" and "decision making," generated 181 abstracts. Only 23 of these publications addressed factors influencing treatment decisions made by men with prostate cancer. Nine additional relevant studies were identified from references in the original 23 articles. Subsequently a search for the term "prostate cancer" using several popular Internet search engines yielded more than 1 million hits. A further search was performed using the key words "prostate cancer" and "prostate" within on-line archives of the United Kingdom television channels BBC, ITV, and channels 4 and 5, and newspapers The Sun, The Daily Mail, The Observer, The Guardian and The Times.

RESULTS

When there is poor quality evidence or little professional consensus to support a particular treatment over another, no clinical guidelines regarding treatment are possible. Patients are faced with a series of options, and the data reveal that the process of choosing between these options is based on input from a large number of sources. These sources differ in the way that benefits of treatment are emphasized over harms and vice versa. We identified little evidence regarding which type of input exerts the greatest influence on patients. It may be that the sources associated with the most bias have the greatest influence.

CONCLUSIONS

There is a paucity of information on how patients with prostate cancer use different types of input in the treatment decision making process. The physician, as principal caregiver, still appears to have the most direct influence on patient choice. Just how long this status will continue is uncertain.