MDCT-imaging of peripheral arterial disease

Contrast-enhanced thin-slice abdominal CT with super-resolution deep learning reconstruction technique: evaluation of image quality and visibility of anatomical structures

PURPOSE

To compare image quality and visibility of anatomical structures on contrast-enhanced thin-slice abdominal CT images reconstructed using super-resolution deep learning reconstruction (SR-DLR), deep learning-based reconstruction (DLR), and hybrid iterative reconstruction (HIR) algorithms.

MATERIALS AND METHODS

This retrospective study included 54 consecutive patients who underwent contrast-enhanced abdominal CT. Thin-slice images (0.5 mm thickness) were reconstructed using SR-DLR, DLR, and HIR. Objective image noise and contrast-to-noise ratio (CNR) for liver parenchyma relative to muscle were assessed. Two radiologists independently graded image quality using a 5-point rating scale for image noise, sharpness, artifact/blur, and overall image quality. They also graded the visibility of small vessels, main pancreatic duct, ureters, adrenal glands, and right adrenal vein on a 5-point scale.

RESULTS

SR-DLR yielded significantly lower objective image noise and higher CNR than DLR and HIR (P < .001). The visual scores of SR-DLR for image noise, sharpness, and overall image quality were significantly higher than those of DLR and HIR for both readers (P < .001). Both readers scored significantly higher on SR-DLR than on HIR for visibility for all structures (P < .01), and at least one reader scored significantly higher on SR-DLR than on DLR for visibility for all structures (P < .05).

CONCLUSION

SR-DLR reduced image noise and improved image quality of thin-slice abdominal CT images compared to HIR and DLR. This technique is expected to enable further detailed evaluation of small structures.

Peripheral artery disease: the new frontiers of imaging techniques to evaluate the evolution of regenerative medicine

Introduction: Stem cells (ESC, iPSC, MSC) are known to have intrinsic regenerative properties. In the last decades numerous findings have favored the development of innovative therapeutic protocols based on the use of stem cells (Regenerative Medicine/Cell Therapy) for the treatment of numerous diseases including PAD, with promising results in preclinical studies. So far, several clinical studies have shown a general improvement of the patient's clinical outcome, however they possess many critical issues caused by the non-randomized design of the limited number of patients examined, the type cells to be used, their dosage, the short duration of treatment and also their delivery strategy. Areas covered: In this context, the use of the most advanced molecular imaging techniques will allow the visualization of very important physio-pathological processes otherwise invisible with conventional techniques, such as angiogenesis, also providing important structural and functional data. Expert opinion: The new frontier of cell therapy applied to PAD, potentially able to stop or even the process that causes the disease, with particular emphasis on the clinical aspects that different types of cells involve and on the use of more innovative molecular imaging techniques now available.

Surveillance and follow-up after revascularization for critical limb ischemia

The purpose of a structured and cost-effective surveillance program after surgical or endovascular intervention for critical limb ischemia is to optimize limb salvage and preserve arterial repair function. Surveillance programs should include clinical, vascular laboratory, and radiographic follow-up, and, when a high-grade progressive stenosis is identified, appropriately timed intervention should be performed. Because many patients with critical limb ischemia are older and many are frail with limited mobility, optimizing the durability of arterial intervention and keeping these patients ambulatory is an important factor in retaining an independent lifestyle and quality of life. Despite the importance of surveillance after arterial intervention, there is a lack of consensus in the literature regarding the efficacy of surveillance, how it should be performed, and well-defined evidence-based guidelines. This review provides an up-to-date scrutiny on this topic and provides recommendations for optimal testing methods, limitations of surveillance testing, and when and how to intervene. These recommendations should be considered in the care of the patient with critical limb ischemia, but with the understanding that patients vary widely and care should be individualized.

Adaptive Bolus-chasing Computed Tomography Angiography in the Cases of Symmetric and Asymmetric Arterial Flows in Peripheral Arteries

Synchronization of the contrast bolus peak and CT imaging aperture is a crucial issue for computed tomography angiography (CTA). It affects the CTA image quality and the amount of contrast dose. A whole-body CTA procedure means to scan from the abdominal aorta to pedal arteries. In this context, the synchronization is much more difficult with the asymmetric arterial flow in lower extremities than in the case of symmetric arterial flow. In this paper, we propose an adaptive optimal controller to chase the contrast bolus peak while it propagates in the aorta and lower extremities with symmetric flow. In the case of asymmetric flow after the contrast bolus splitting into two lower limbs, we propose a dynamic programming approach to cover the lower limbs optimally. Simulation and experimental results show that the proposed methods outperform the current constant-speed method substantially.

Medical and endovascular management of critical limb ischemia

Critical limb ischemia (CLI) is the term used to designate the condition in which peripheral artery disease has resulted in resting leg or foot pain or in a breakdown of the skin of the leg or foot, causing ulcers or tissue loss. If not revascularized, CLI patients are at risk for limb loss and for potentially fatal complications from the progression of gangrene and the development of sepsis. The management of CLI requires a multidisciplinary team of experts in different areas of vascular disease, from atherosclerotic risk factor management to imaging, from intervention to wound care and physical therapy. In the past decade, the most significant change in the treatment of CLI has been the increasing tendency to shift from bypass surgery to less invasive endovascular procedures as first-choice revascularization techniques, with bypass surgery then reserved as backup if appropriate. The goals of intervention for CLI include the restoration of pulsatile, inline flow to the foot to assist wound healing, the relief of rest pain, the avoidance of major amputation, preservation of mobility, and improvement of patient function and quality of life. The evaluating physician should be fully aware of all revascularization options in order to select the most appropriate intervention or combination of interventions, while taking into consideration the goals of therapy, risk-benefit ratios, patient comorbidities, and life expectancy. We discuss the incidence, risk factors, and prognosis of CLI and the clinical presentation, diagnosis, available imaging modalities, and medical management (including pain and ulcer care, pharmaceutical options, and molecular therapies targeting angiogenesis). The endovascular approaches that we review include percutaneous transluminal angioplasty (with or without adjunctive stenting); subintimal angioplasty; primary femoropopliteal and infrapopliteal deployment of bare nitinol, covered, drug-eluting, or bioabsorbable stents; cryoplasty; excimer laser-assisted angioplasty; excisional atherectomy; and cutting balloon angioplasty.

The importance of multidetector computed tomography in the vascular imaging

A több detektorsoros spirál-CT-berendezések és a hozzájuk tartozó speciális rekonstrukciós szoftverek bevezetése lehetővé tette az erek jó minőségű CT-vizsgálatát. Cél és módszerek: A szerzők ismertetik a CT-angiográfiai vizsgálatok elvét, technikáját, amelyet az elmúlt három évben közel 700 saját betegükön végzett vizsgálataik eredményeivel, tapasztalataival egészítenek ki. Bemutatják a CT-angiográfia jelentőségét, valamint annak más vascularis képalkotó eljárások helyett vagy melletti alkalmazhatóságát. Következtetések: A CT-angiográfia gyors, noninvazív vizsgálati módszer, amellyel – önmagában vagy más vizsgálattal kiegészítve – pontos diagnózis állítható fel.

[Critical limb ischemia]

Critical limb ischemia can be divided into acute and chronic forms. All patients suspected of the acute form should be evaluated immediately, as urgent revascularization is usually necessary. Chronic critical limb ischemia is the most complicated type of peripheral artery disease (PAD). Typical for it are pain at rest and necrosis or gangrene. The most important known risk factors are nicotine, hypertension, diabetes, and hyperlipoproteinemia. Patients suffering from PAD run a significantly higher risk of cardiovascular or cerebrovascular events and therefore should be on permanent antithrombotic therapy as secondary prophylaxis. Besides clinical examination and determination of the ankle/brachial index, complementary imaging is mandatory. Here angiography is the gold standard. For therapy surgical and other interventional procedures are available. The decision on individual therapy follows an interdisciplinary approach based on an international consensus (TASC classification).

Quality improvement guidelines for endovascular treatment of iliac artery occlusive disease

Endovascular therapy is the treatment of choice for type A and the preferred treatment for type B lesions. In selective patients, this type of treatment can be applied in type C and even type D lesions. Ipsilateral femoral, contralateral femoral, and brachial approach and both the intraluminal and subintimal space can be used for successful recanalization. The application of stents has improved the immediate hemodynamic and probably long-term clinical results of iliac percutaneous transluminal angioplasty. However, the superiority of primary or direct stenting over selective stenting has not been proven yet. The choice of stent type depends on lesion morphology and location but otherwise there is insufficient evidence to support the use of a particular stent design. There is insufficient evidence to justify routine use of covered stents. All patients should receive antiaggregant therapy following endovascular recanalization of iliac arteries. There is no consensus regarding prophylaxis with antibiotics in iliac recanalization procedures.

Multidetector computed tomographic angiography of the cardiovascular system

The introduction of multidetector computed tomography (MDCT) is considered a dramatic development in CT imaging that has direct implication in the imaging of various systems, in particular the cardiovascular system. The advantages of MDCT are an enormous increase in imaging acquisition speed, more coverage of the patient, and high spatial resolution. This article reviews the recent developments in CT angiography and discusses the clinical application relevant to diagnosis and endovascular treatment of cardiovascular diseases.

Multi-detector row computed tomography angiography of peripheral arterial disease

With the introduction of multi-detector row computed tomography (MDCT), scan speed and image quality has improved considerably. Since the longitudinal coverage is no longer a limitation, multi-detector row computed tomography angiography (MDCTA) is increasingly used to depict the peripheral arterial runoff. Hence, it is important to know the advantages and limitations of this new non-invasive alternative for the reference test, digital subtraction angiography. Optimization of the acquisition parameters and the contrast delivery is important to achieve a reliable enhancement of the entire arterial runoff in patients with peripheral arterial disease (PAD) using fast CT scanners. The purpose of this review is to discuss the different scanning and injection protocols using 4-, 16-, and 64-detector row CT scanners, to propose effective methods to evaluate and to present large data sets, to discuss its clinical value and major limitations, and to review the literature on the validity, reliability, and cost-effectiveness of multi-detector row CT in the evaluation of PAD.

Multi-slice CT (MSCT) angiography for assessment of traumatic lesions of lower limbs peripheral arteries

AIM

The aim of this study was to evaluate the feasibility and effectiveness of multi-slice computed tomography (MSCT) angiography for the assessment of traumatic lesions involving the arteries of the lower limbs.

MATERIALS AND METHODS

Forty-seven patients with suspected arterial post-traumatic lesions of lower limbs underwent MSCT angiography (4 x 2.5-mm collimation, 3-mm slice width). The standards of reference were: digital subtraction angiography (DSA; patients with inconclusive/doubtful or positive MSCT angiography indicating a need for intravascular treatment), surgical findings (patients with positive MSCT angiography indicating a need for surgery), or clinical/investigational follow-up (patients with negative MSCT angiography and no need for further diagnostic procedures or surgery).

RESULTS

All CT exams were technically adequate. Sensitivity, specificity, and overall diagnostic accuracy of MSCT angiography were 96.3, 90, and 93.6%, respectively, relative to the reference of standard findings. In 44 out of 47 patients, MSCT angiography allowed a correct continuation of the diagnostic work-up.

CONCLUSION

MSCT angiography is a reliable fast tool for diagnosing traumatic vascular lesions, providing results comparable to DSA.

Contrast-enhanced MR angiography of the chest and abdomen with use of controlled apnea in children

PURPOSE

To retrospectively determine if controlled apnea improves the image quality of contrast material--enhanced magnetic resonance (MR) angiography of the chest and abdomen in children.

MATERIALS AND METHODS

Institutional review board approval and waiver of informed consent were obtained for this HIPAA-compliant study. The authors evaluated contrast-enhanced MR angiographic procedures performed in the chest, abdomen, or both, in 23 children (14 boys, nine girls; age range, 1 month to 8 years) who were under general anesthesia. All patients underwent mechanical ventilation with preoxygenation (100% oxygen) prior to controlled apnea during image acquisition. In control subjects, the authors assessed contrast-enhanced MR angiographic procedures performed in the chest, abdomen, or both, in 23 children (matched for age and type of study with children in the controlled apnea group; 11 boys, 12 girls; age range, 1 month to 8 years) who were under general anesthesia (n=15) or deep sedation (n=8) and were breathing spontaneously during image acquisition. MR angiograms of the chest, abdomen, or both, were assessed for image quality, motion artifacts, and vessel definition by two radiologists working in consensus with a subjective grading scale. Wilcoxon signed rank test was used to assess differences in measurements.

RESULTS

Image quality was rated excellent in 97% (30 of 31) of studies with controlled apnea and in 30% (nine of 31) of control studies (P<.001). Motion artifacts were absent in 97% (30 of 31) of studies with controlled apnea and 13% (four of 31) of control studies (P<.001). Vessel sharpness was rated as being significantly better on images obtained with controlled apnea (P<.05). There were no complications caused by anesthesia or sedation in either group.

CONCLUSION

Controlled apnea is highly effective in children for eliminating respiratory motion artifacts with contrast-enhanced MR angiographic studies, resulting in greatly improved image quality and spatial resolution.

Virtual Whipple: Preoperative Surgical Planning with Volume-Rendered MDCT Images to Identify Arterial Variants Relevant to the Whipple Procedure

OBJECTIVE

The purposes of this study were to combine a thorough understanding of the technical aspects of the Whipple procedure with advanced rendering techniques by introducing a virtual Whipple procedure and to evaluate the utility of this new rendering technique in prediction of the arterial variants that cross the anticipated surgical resection plane.

CONCLUSION

The virtual Whipple is a novel technique that follows the complex surgical steps in a Whipple procedure. Three-dimensional reconstructed angiographic images are used to identify arterial variants for the surgeon as part of the preoperative radiologic assessment of pancreatic and ampullary tumors.

Prediction of aortic peak enhancement in monophasic contrast injection protocols at multidetector CT: phantom and patient studies

PURPOSE

The aim of this study was to investigate whether it is possible to predict aortic peak enhancement (APE) from the contrast dose and injection rate.

MATERIALS AND METHODS

We first undertook an experimental study using a flow phantom that simulates the human circulation. We delivered 90-150 ml of iomeprol-350 at various injection rates and measured the APE values of the simulated aorta. In our clinical study we randomized 20 patients into four groups. In groups A, B, and C the iodine dose per kilogram of body weight (BW) ranged from 450 to 600 mg, and the injection duration was fixed at 30 s; group D received 450 mg/kg over 25 s. We then measured APE in all patients at the whole aorta, averaged the three highest values, and took the result as APE.

RESULTS

In the phantom study, the decision coefficient for the best-fit equation obtained by multiple regression analysis of the relation between the iodine dose and injection rate and the simulated APE was high (0.93). In the patient study, the predicted APE values almost corresponded with the averaged APE values when we applied the fitness equation.

CONCLUSION

Using our fitness equation, APE on contrast-enhanced computed tomography can be predicted from the iodine dose and the contrast injection rate per patient weight.

Imaging of peripheral arteries by 16-row multidetector computed tomography angiography: a feasible tool?

OBJECTIVE

To evaluate the efficacy of multidetector (16-row) computed tomography (MDCT) in imaging the upper and lower limb arterial tree in trauma and peripheral arterial occlusive disease (PAOD).

METHODS

Thirty-three patients underwent MDCT angiography (MDCTA) of the upper or the lower limb on 16-row MDCT scanner between November, 2004 and July, 2005. The findings were compared with the surgical outcome in cases with trauma and suspected arterial injuries or color Doppler correlation was obtained for patients of PAOD.

RESULTS

MDCTA allowed a comprehensive diagnostic work-up in all trauma cases with suspected arterial injuries. In the 23 cases of PAOD, MDCT adequately demonstrated the presence of stenosis or occlusion, its degree and extent, the presence of collaterals and plaques.

CONCLUSION

Our experience of CT angiography (CTA) with 16-row MDCT scanner has clearly demonstrated its efficacy as a promising, new, fast, accurate, safe and non-invasive imaging modality of choice in cases of trauma with suspected arterial injuries and as a useful screening modality in cases of PAOD for diagnosis and for grading.

Bolus characteristics based on Magnetic Resonance Angiography

Background

A detailed contrast bolus propagation model is essential for optimizing bolus-chasing Computed Tomography Angiography (CTA). Bolus characteristics were studied using bolus-timing datasets from Magnetic Resonance Angiography (MRA) for adaptive controller design and validation.

Methods

MRA bolus-timing datasets of the aorta in thirty patients were analyzed by a program developed with MATLAB. Bolus characteristics, such as peak position, dispersion and bolus velocity, were studied. The bolus profile was fit to a convolution function, which would serve as a mathematical model of bolus propagation in future controller design.

Results

The maximum speed of the bolus in the aorta ranged from 5–13 cm/s and the dwell time ranged from 7–13 seconds. Bolus characteristics were well described by the proposed propagation model, which included the exact functional relationships between the parameters and aortic location.

Conclusion

The convolution function describes bolus dynamics reasonably well and could be used to implement the adaptive controller design.

Arteriogenesis: Noninvasive Quantification with Multi–Detector Row CT Angiography and Three-dimensional Volume Rendering in Rodents

PURPOSE

To evaluate two-dimensional (2D) multi-detector row computed tomographic (CT) angiography and three-dimensional (3D) volume rendering for depiction of patterns of arterial growth and quantification of blood vessel density and volume.

MATERIALS AND METHODS

The institutional animal care and use committee approved this study. The right femoral artery and its branches were ligated and excised in 16 inbred Lewis rats; animals were randomly assigned to receive 70 microL Dulbecco's modified Eagle's medium (DMEM) or 1.5 x 10(7) bone marrow-derived mononuclear cells (BMC) from isogenic donor rats in 70 microL DMEM. At 2 weeks, CT angiography was performed with injection of 0.45 mL barium sulfate suspension at 0.7 mL/min, followed by silver staining. Number of blood vessels, area, mean area, volume, and blood vessel size distribution derived from digitally subtracted 2D CT angiographic sections were quantified; 3D images were reconstructed. Two-way analysis of variance and paired and unpaired Student t tests were performed.

RESULTS

CT angiography showed two patterns of arterial growth: collateral arterial formation and branching arteriogenesis. Two-way analysis of variance indicated that differences within subjects (ischemic vs nonischemic legs) and between subjects (BMC vs DMEM treatment) were significant for total blood vessel area, total blood vessel volume, and mean of blood vessel area (P < .001). In the BMC group, there were significantly more arteries (mean, 241.6 +/- 77.0 [standard deviation] vs 196.4 +/- 75.2, P = .028), but mean cross-sectional area of these arteries was smaller in ischemic versus nonischemic legs (5.4 mm(2) +/- 1.2 vs 6.8 mm(2) +/- 1.3, P = .006). Total arterial area and volume did not differ significantly between ischemic and nonischemic legs.

CONCLUSION

BMC injection had a substantial effect on arteriogenesis, with normalization of total arterial area and volume in the BMC group; this effect was successfully depicted.

Multidetector-row computed tomography in the planning of abdominal perforator flaps

An accurate preoperative evaluation of the vascular anatomy of the abdominal wall is extremely valuable in improving the surgical strategy in abdominal perforator flaps. The multidetector-row computer tomography offers thin slice coverage of extended volumes with an extremely high spatial resolution. From October 2003 to December 2004, 66 female patients had breast reconstruction surgery in our department using the deep inferior epigastric artery perforator flap. Our multidetector-row computer tomography studies were performed using a 16-detector-row computer tomography scanner. The image assessment was carried out using the following protocol: we first identified the best three perforators from each side of the abdomen. Then we conducted a three-dimensional reconstruction of the abdomen by identifying exactly where the three best perforators emerged from the rectus abdominis fascia. We then transferred the data obtained from the image to the patient using a coordinate system. In addition, we also placed the dominant perforators in the patient by using a conventional hand-held Doppler. During the operation we compared intra-operative findings, Doppler results and computer tomography outcomes. Neither false positive nor false negative results were found in the computer tomography outcome. Multidetector-row computer tomography provides us with an easy method of interpreting the virtual anatomic dissection in three dimensions. It has high sensitivity and specificity and provides a good quality evaluation of the perforator vessels. This information allows reduction of operating time and safer performance of surgery. The multidetector-row computer tomography is a highly effective tool in the preoperative study of abdominal perforator flaps.