Management of peripheral arterial disease: Role of computed tomography angiography and magnetic resonance angiography

Quantitative hemodynamic assessment of stenotic below-the-knee arteries using spatio-temporal bolus tracking on 4D-CT angiography

BACKGROUND

Peripheral arterial disease (PAD) is a chronic occlusive disease that restricts blood flow in the lower limbs, causing partial or complete blockages of the blood flow. While digital subtraction angiography (DSA) has traditionally been the preferred method for assessing blood flow in the lower limbs, advancements in wide beam Computed Tomography (CT), allowing successive acquisition at high frame rate, might enable hemodynamic measurements.

PURPOSE

To quantify the arterial blood flow in stenotic below-the-knee (BTK) arteries. To this end, we propose a novel method for contrast bolus tracking and assessment of quantitative hemodynamic parameters in stenotic arteries using 4D-CT.

METHODS

Fifty patients with suspected PAD underwent 4D-CT angiography in addition to the clinical run-off computed tomography angiography (CTA). From these dynamic acquisitions, the BTK arteries were segmented and the region of maximum blood flow was extracted. Time attenuation curves (TAC) were estimated using 2D spatio-temporal B-spline regression, enforcing both spatial and temporal smoothness. From these curves, quantitative hemodynamic parameters, describing the shape of the propagating contrast bolus were automatically extracted. We evaluated the robustness of the proposed TAC fitting method with respect to interphase delay and imaging noise and compared it to commonly used approaches. Finally, to illustrate the potential value of 4D-CT, we assessed the correlation between the obtained hemodynamic parameters and the presence of PAD.

RESULTS

280 out of 292 arteries were successfully segmented, with failures mainly due to a delayed contrast arrival. The proposed method led to physiologically plausible hemodynamic parameters and was significantly more robust compared to 1D temporal regression. A significant correlation between the presence of proximal stenoses and several hemodynamic parameters was found.

CONCLUSIONS

The proposed method based on spatio-temporal bolus tracking was shown to lead to stable and physiologically plausible estimation of quantitative hemodynamic parameters, even in the case of stenotic arteries. These parameters may provide valuable information in the evaluation of PAD and contribute to its diagnosis.

Fluoroscopy with MRA fusion image guidance in endovascular iliac artery interventions: study protocol for a randomized controlled trial (3DMR-Iliac-roadmapping study)

BACKGROUND

Endovascular iliac artery interventions rely on the use of two-dimensional digital subtraction angiographies with an iodinated contrast agent and ionizing radiation. The amount of iodinated contrast agent should be limited because of its potentially nephrotoxic effects. Three-dimensional (3D) image fusion requires registration of a preprocedural magnetic resonance angiogram (MRA) or computed tomography (CT) angiogram to a perprocedurally acquired cone-beam CT or two fluoroscopic orthogonal projections. After registration, the 3D angiography images can be overlaid on the fluoroscopy screen and will follow table and C-arm movements. This study will assess the added value of the 3D image fusion technique in iliac artery interventions regarding the amount of the iodinated contrast agent administered.

METHODS/DESIGN

The study cohort will comprise 106 patients (> 18 years) with symptomatic common and/or external iliac artery stenoses or occlusions and a recent (< 6 months) diagnostic MRA from the pelvis through the lower extremities, for which an endovascular intervention is indicated. Patients will be randomized into the control or study group (i.e. treatment without or with 3D image fusion guidance). The primary endpoint is the amount of administered iodinated contrast agent (mL). Secondary outcomes are technical success of the procedure, defined as < 30% residual stenosis over the treated lesion, fluoroscopy time, and radiation dose as dose area product (mGycm2). Patient participation in the study will be completed after hospital discharge.

DISCUSSION

This study is a randomized controlled multicenter trial to provide evidence on the effect of the 3D image fusion technique on the amount of administered iodinated contrast during endovascular common and/or external iliac artery interventions.

TRIAL REGISTRATION

Nederlands Trial Register, NTR5008 . Registered on 16 December 2014.

Comparison of CT and MR angiography in evaluation of peripheral arterial disease before endovascular intervention

BACKGROUND

Multidetector computed tomography angiography (MDCTA) and magnetic resonance angiography (MRA) are accurate techniques for selecting patients with peripheral arterial disease for surgical and endovascular treatment. No studies in the literature have directly compared MDCTA and MRA to establish which one should be employed, in patients suitable for both techniques, before endovascular treatment.

PURPOSE

To compare diagnostic performance of MDCTA vs MRA before endovascular intervention.

MATERIAL AND METHODS

We prospectively compared MDCTA (64 slices scanner) and MRA (1.5 T scanner; 3D gadolinium-enhanced bolus-chase acquisition plus time resolved acquisition on calves) to stratify 35 patients according to the TASC II score and a runoff severity score. We also evaluated the accuracy of both techniques in each arterial segment. Selective angiography performed during the treatment was the standard of reference.

RESULTS

MDCTA and MRA accurately classify disease in the aorto-iliac (accuracy 0.92 for MDCTA and MRA) and femoro-popliteal (MDCTA 0.94, MRA 0.90) segments. MDCTA was more accurate in stratifying disease in the infrapopliteal segments (0.96 vs. 0.9) and in assessing the impairment of runoff arteries (0.92 vs. 0.85) at per-segment analysis. MDCTA showed a higher confidence and a shorter examination time.

CONCLUSION

Our results suggest that MDCTA can be considered as a first-line investigation in patients being candidates for endovascular procedures when clinical history or duplex sonographic evaluation are indicative of severe impairment of the infrapopliteal segment.

Management of Infrapopliteal Arterial Disease: Critical Limb Ischemia

According to the TransAtlantic Inter-Society Consensus Document on Management of Peripheral Arterial Disease, "there is increasing evidence to support a recommendation for angioplasty in patients with critical limb ischemia and infrapopliteal artery occlusion." Management of infrapopliteal artery disease starts with diagnosis using modern preprocedural noninvasive and invasive imaging. Interventionalists need to learn the role of chronic total occlusion cap analysis and collateral zone recognition in angiosome-directed interventions for management of critical limb ischemia and be familiar with equipment and device selection and a stepwise approach for endovascular interventions. Interventionalists need to know which crossing tools to use to successfully cross-complex chronic total occlusion caps.

A comparison of risk and protective factors related to suicide ideation among residents and specialists in academic medicine

Background

Physicians have an elevated risk of experiencing suicidal thoughts, which might be due to work-related factors. However, the hierarchical work positions as well as work-related health differ among resident and specialist physicians. As such, the correlates of suicide ideation may also vary between these two groups.

Methods

In the present study, work- and health-related factors and their association with suicidal thoughts among residents (n = 234) and specialists (n = 813) working at a university hospital were examined using cross-sectional data.

Results

Logistic regression analysis showed that having supportive meetings was associated with a lower level of suicide ideation among specialists (OR = 0.68, 95% CI: 0.50-0.94), while an empowering leadership was related to a lower level of suicide ideation among residents (OR = 0.55, 95% CI: 0.32-0.94). Having been harassed at work was associated with suicidal ideation among specialists (OR = 2.26, 95% CI: 1.31-3.91). In addition, sickness presenteeism and work disengagement were associated with suicide ideation in both groups of physicians.

Conclusions

These findings suggest that different workplace interventions are needed to prevent suicide ideation in residents and specialists.