Aorta and iliac arteries: single versus multiple detector-row helical CT angiography

Optical coherence tomography angiography for noninvasive evaluation of angiogenesis in a limb ischemia mouse model

We developed an optical coherence tomography angiography technique by improving the speckle contrast algorithm and the imaging process. This technique, which can achieve angiogenesis imaging in vivo without increasing trauma, was used to evaluate the microvasculature in limb ischemia mice. Sixteen left hindlimb ischemia mice were randomly allocated into CuSO₄ and saline groups. Within 7 days after treatment, limb ischemic damage, temperature and histological staining were assessed by traditional methods. In addition, angiogenesis was evaluated using an optical coherence tomography angiography system in vivo. All results were compared. After 7 days of treatment, both the ischemic tissue damage score and temperature ratio of the CuSO₄ group were significantly higher than those of the control group (all P < 0.05). The number of CD31-positive endothelial cells in the CuSO₄ group (0.1836 ± 0.0153) was significantly greater than that in the saline control group (0.0436 ± 0.0069) (P < 0.001). Optical coherence tomography angiography showed that the vessel area density of mice in the CuSO₄ group (0.2566 ± 0.0060) was significantly greater than that of mice in the control group (0.2079 ± 0.0202) (P = 0.027). Optical coherence tomography angiography represents a practical and effective method for observing angiogenesis in the mouse hindlimb in vivo without increasing trauma.

Plaque imaging with CT-a comprehensive review on coronary CT angiography based risk assessment

CT based technologies have evolved considerably in recent years. Coronary CT angiography (CTA) provides robust assessment of coronary artery disease (CAD). Early coronary CTA imaging-as a gate-keeper of invasive angiography-has focused on the presence of obstructive stenosis. Coronary CTA is currently the only non-invasive imaging modality for the evaluation of non-obstructive CAD, which has been shown to contribute to adverse cardiac events. Importantly, improved spatial resolution of CT scanners and novel image reconstruction algorithms enable the quantification and characterization of atherosclerotic plaques. State-of-the-art CT imaging can therefore reliably assess the extent of CAD and differentiate between various plaque features. Recent studies have demonstrated the incremental prognostic value of adverse plaque features over luminal stenosis. Comprehensive coronary plaque assessment holds potential to significantly improve individual risk assessment incorporating adverse plaque characteristics, the extent and severity of atherosclerotic plaque burden. As a result, several coronary CTA based composite risk scores have been proposed recently to determine patients at high risk for adverse events. Coronary CTA became a promising modality for the evaluation of functional significance of coronary lesions using CT derived fractional flow reserve (FFR-CT) and/or rest/dynamic myocardial CT perfusion. This could lead to substantial reduction in unnecessary invasive catheterization procedures and provide information on ischemic burden of CAD. Discordance between the degree of stenosis and ischemia has been recognized in clinical landmark trials using invasive FFR. Both lesion stenosis and composition are possibly related to myocardial ischemia. The evaluation of lesion-specific ischemia using combined functional and morphological plaque information could ultimately improve the diagnostic performance of CTA and thus patient care. In this review we aimed to summarize current evidence on comprehensive coronary artery plaque assessment using coronary CTA.

Spectrum of Abdominal Aortic Disease in a Tertiary Health Care Setup: MDCT Based Observational Study

INTRODUCTION

Abdominal aortic disease is an important cause of clinical disability that requires early detection by imaging methods for prompt and effective management. Understanding regional disease pattern and prevalence has a bearing on healthcare management and resource planning. Non-invasive, conclusive imaging strategy plays an important role in the detection of disease. Multi-Detector Computed Tomography (MDCT) with its technological developments provides affordable, accurate and comprehensive imaging solution.

AIM

To evaluate regional demography of abdominal aortic disease spectrum detected using MDCT imaging data in a tertiary hospital.

MATERIALS AND METHODS

A descriptive study was conducted based on MDCT imaging data of patients who were investigated with clinical diagnosis of abdominal aortic disease, from March 2008-2010, over a period of 24 months. Patients were examined with the contrast-enhanced MDCT examination. Morphological diagnosis of the aortic disease was based on changes in relative aortic caliber, luminal irregularity, presence of wall calcification, dissection or thrombus and evidence of major branch occlusion. Patients were categorized into four groups based on imaging findings. MDCT information and associated clinical parameters were examined and correlated to management of patient. Descriptive statistical data, namely mean, standard deviation and frequency of disease were evaluated.

RESULTS

A total of 90 out of 210 patients (43%) were detected with the abdominal aortic abnormality defined by imaging criteria. Group I, comprising of patients with atherosclerosis -including those with complications, constituted 65.5% of the patients. Group II represented patients with aneurysms (45.5%). Group III, consisting of 32.2% of the patients, contained those with dissections. The rest of the patients, including patients with aorto-arteritis, were classified as group IV. Eight patients with aneurysm and one patient with aorto-arteritis were considered for surgical treatment. Ten patients with dissection underwent endovascular procedure. Rest of the patients was managed conservatively.

CONCLUSION

Aortic disease was observed in 43% of investigated patients. Atherosclerosis with and without aortic aneurysm constituted the largest group. MDCT provided comprehensive information about the lesion and associated complications. In view of the wider availability and desired imaging qualities, MDCT provided optimal information for diagnosis and management of aortic pathology. Majority of our patients (90%) were treated conservatively.

[Evaluation of Dose Reduction of the Active Collimator in Multi Detector Row CT]

The purpose of this study was to evaluate the performance of active collimator by changing acquisition parameters and obtaining dose profiles in z-axis direction. Dose profiles along z-axis were obtained using XRQA2 Gafchromic film. As a result, the active collimator reduced overranging about 55% compared to that without the active collimator. In addition, by changing the combination of X-ray beam width (32 mm, 40 mm), pitch factor (1.4, 0.6), and the X-ray tube rotation time (0.5 s/rot, 1.0 s/rot), the overranging changed from 19.4 to 34.9 mm. Although the active collimator is effective for reducing overranging, it is necessary to adjust acquisition parameters by taking the properties of the active collimator for acquisition parameters, especially setting beam width, into consideration.

Regional Mapping of Aortic Wall Stress by Using Deformable, Motion-coherent Modeling based on Electrocardiography-gated Multidetector CT Angiography: Feasibility Study

Purpose To investigate the feasibility of deformable, motion-coherent modeling based on electrocardiography-gated multidetector computed tomographic (CT) angiography of the thoracic aorta and to evaluate whether quantifiable information on aortic wall stress as a function of patient-specific cardiovascular parameters can be gained. Materials and Methods For this institutional review board-approved, HIPAA-compliant study, thoracic electrocardiography-gated dual-source multidetector CT angiographic images were used from 250 prospectively enrolled patients (150 men, 100 women; mean age, 79 years). On reconstructed 50-phase CT angiographic images, aortic strain and deformation were determined at seven cardiac and aortic locations. One-way analysis of variance was used by assessing the magnitude for longitudinal and axial strain and axial deformation, as well as time-resolved peak and maxima count for longitudinal strain and axial deformation. Interdependencies between aortic strain and deformation with extracted hemodynamic parameters were evaluated. Results With increasing heart rates, there was a significant decrease in longitudinal strain (P = .009, R(2) = 0.95) and a decrease in the number of longitudinal strain peaks (P < .001, R(2) = 0.79); however, a significant increase in axial deformation (P < .001, R(2) = 0.31) and axial strain (P = .009, R(2) = 0.61) was observed. Increasing aortic blood velocity led to increased longitudinal strain (P = .018, R(2) = 0.42) and longitudinal strain peak counts (P = .011, R(2) = 0.48). Pronounced motion in the longitudinal direction limited motion in the axial plane (P < .019, R(2) = 0.29-0.31). Conclusion The results of this study render a clinical basis and provide proof of principle for the use of deformable, motion-coherent modeling to provide quantitative information on physiological motion of the aorta under various hemodynamic circumstances. (©) RSNA, 2016 Online supplemental material is available for this article.

128-slice CT angiography of the aorta without ECG-gating: efficacy of faster gantry rotation time and iterative reconstruction in terms of image quality and radiation dose

OBJECTIVE

To evaluate image quality and radiation dose of non ECG-gated 128-slice CT angiography of the aorta (CTAA) with fast gantry rotation time and iterative reconstruction.

METHODS

Four hundred and eighty patients underwent non ECG-gated CTAA. Qualitative and quantitative image quality assessments were performed. Radiation dose was assessed and compared with the dose of patients who underwent ECG-gated CTAA (n = 126) and the dose of previous CTAA performed with another CT (n = 339).

RESULTS

Image quality (aortic root-ascending portion) was average-to-excellent in more than 94% of cases, without any non-diagnostic scan. For proximal coronaries, image quality was average-to-excellent in more than 50%, with only 21.5% of non-diagnostic cases. Quantitative analysis results were also good. Mean radiation dose for thoracic CTAA was 5.6 mSv versus 20.6 mSv of ECG-gated protocol and 20.6 mSv of 16-slice CTAA scans, with an average dose reduction of 72.8% (p < 0.001). Mean radiation dose for thoracic-abdominal CTAA was 9.7 mSv, versus 20.9 mSv of 16-slice CTAA scans, with an average dose reduction of 53.6% (p < 0.001).

CONCLUSIONS

Non ECG-gated 128-slice CTAA is feasible and able to provide high quality visualization of the entire aorta without significant motion artefacts, together with a considerable dose and contrast media volume reduction.

KEY POINTS

• CT image quality of aortic root-ascending aorta is challenging. • Non ECG-gated scans are often limited by pulsatility artefacts. • ECG-gated examinations are usually limited by high radiation doses. • Non ECG-gated 128-slice low dose CTAA provides high quality images. • 128-slice CTAA low dose protocol could frequently replace ECG-gated CTAA.

MDCT of endoleaks following endovascular repair of abdominal aortic aneurysms

Endovascular aneurysm repair has been used to repair abdominal aortic aneurysms but necessitates surveillance to diagnose the delayed possibility of endoleak formation. Multi-detector computer tomography (MDCT) of the abdomen is one imaging technique used to diagnose enlargement of the aneurysm sac that may be indicative of endoleaks. MDCT has a role in identifying the initial endoleak formation and providing signs suggestive of the specific endoleak subtype; thus it is necessary for radiologists to be familiar with the findings of endoleak seen on MDCT. In this pictorial review, we explore the various types of endoleaks and their appearance on MDCT.

High-pitch, low-voltage and low-iodine-concentration CT angiography of aorta: assessment of image quality and radiation dose with iterative reconstruction

Objective

To assess the image quality of aorta obtained by dual-source computed tomography angiography (DSCTA), performed with high pitch, low tube voltage, and low iodine concentration contrast medium (CM) with images reconstructed using iterative reconstruction (IR).

Methods

One hundred patients randomly allocated to receive one of two types of CM underwent DSCTA with the electrocardiogram-triggered Flash protocol. In the low-iodine group, 50 patients received CM containing 270 mg I/mL and were scanned at low tube voltage (100 kVp). In the high-iodine CM group, 50 patients received CM containing 370 mg I/mL and were scanned at the tube voltage (120 kVp). The filtered back projection (FBP) algorithm was used for reconstruction in both groups. In addition, the IR algorithm was used in the low-iodine group. Image quality of the aorta was analyzed subjectively by a 3-point grading scale and objectively by measuring the CT attenuation in terms of the signal- and contrast-to-noise ratios (SNR and CNR, respectively). Radiation and CM doses were compared.

Results

The CT attenuation, subjective image quality assessment, SNR, and CNR of various aortic regions of interest did not differ significantly between two groups. In the low-iodine group, images reconstructed by FBP and IR demonstrated significant differences in image noise, SNR, and CNR (p<0.05). The low-iodine group resulted in 34.3% less radiation (4.4 ± 0.5 mSv) than the high-iodine group (6.7 ± 0.6 mSv), and 27.3% less iodine weight (20.36 ± 2.65 g) than the high-iodine group (28 ± 1.98 g). Observers exhibited excellent agreement on the aortic image quality scores (κ = 0.904).

Conclusions

CT images of aorta could be obtained within 2 s by using a DSCT Flash protocol with low tube voltage, IR, and low-iodine-concentration CM. Appropriate contrast enhancement was achieved while maintaining good image quality and decreasing the radiation and iodine doses.

Computed tomography: revolutionizing the practice of medicine for 40 years

Computed tomography (CT) has had a profound effect on the practice of medicine. Both the spectrum of clinical applications and the role that CT has played in enhancing the depth of our understanding of disease have been profound. Although almost 90 000 articles on CT have been published in peer-reviewed journals over the past 40 years, fewer than 5% of these have been published in Radiology. Nevertheless, these almost 4000 articles have provided a basis for many important medical advances. By enabling a deepened understanding of anatomy, physiology, and pathology, CT has facilitated key advances in the detection and management of disease. This article celebrates this breadth of scientific discovery and development by examining the impact that CT has had on the diagnosis, characterization, and management of a sampling of major health challenges, including stroke, vascular diseases, cancer, trauma, acute abdominal pain, and diffuse lung diseases, as related to key technical advances in CT and manifested in Radiology.

CT angiography after 20 years: a transformation in cardiovascular disease characterization continues to advance

Through a marriage of spiral computed tomography (CT) and graphical volumetric image processing, CT angiography was born 20 years ago. Fueled by a series of technical innovations in CT and image processing, over the next 5-15 years, CT angiography toppled conventional angiography, the undisputed diagnostic reference standard for vascular disease for the prior 70 years, as the preferred modality for the diagnosis and characterization of most cardiovascular abnormalities. This review recounts the evolution of CT angiography from its development and early challenges to a maturing modality that has provided unique insights into cardiovascular disease characterization and management. Selected clinical challenges, which include acute aortic syndromes, peripheral vascular disease, aortic stent-graft and transcatheter aortic valve assessment, and coronary artery disease, are presented as contrasting examples of how CT angiography is changing our approach to cardiovascular disease diagnosis and management. Finally, the recently introduced capabilities for multispectral imaging, tissue perfusion imaging, and radiation dose reduction through iterative reconstruction are explored with consideration toward the continued refinement and advancement of CT angiography.

Retrospective analysis of incidence of peroneal artery hypoplasia in 101 free fibula transfers and new classification of popliteal branch anomalies

It is generally recognised by surgeons that there are anatomical variations of the popliteal artery and its branches, and knowledge of these has important clinical implications for fibula flap harvest. The aim of this study was to report our experience on 101 fibula free flaps, highlighting a new type of anatomical variation of the peroneal artery in a patient undergoing osteocutaneous fibula free flap for tibial reconstruction. During flap harvest, the peroneal vascular pedicle was shown to be hypoplastic and aberrant to its origin, branching between the proximal and medium third of the leg from the posterior tibialis artery with a diameter of 1mm. A modification of Kim's classification with the addition of a further "type IIID" group is suggested, to include peroneal artery hypoplasia or aplasia. This is an uncommon case of a rare infrapopliteal branching pattern that was undetected clinically and sonographically, exposing both the surgeon and patient to high risk of flap failure and/or leg ischaemic complication. Surgeons conducting free fibula transfer surgery should be aware of such a possibility as well as other variations, and could consider performing routine angiographic study on the donor limb, or they may be skilful enough to apply instant tricks to enable them to conduct the procedure safely.

Multislice CT: technical principles and future trends

Multislice scanning has substantially improved the performance of CT scanners, and thus the relation between scan duration, available scan length, and spatial resolution along the patient axis (z-axis). Near-isotropic imaging of whole organ systems is already possible with 4-slice scanners, but only with 8- to 16-slice scanners can the scan duration be shortened as well. Reconstructing overlapping thin-section data ("secondary raw data set") provides the basis for image reconstruction in any desired plane. By using thick multiplanar reformation (MPR) techniques, image quality can be improved while keeping patient dose low. Using unfavorable scanning parameters, exposure dose can be substantially increased compared with single-slice scanning, but thick MPR and individual-dose modulation techniques can provide the basis for dose reduction. Low-kVp scanning, in particular, is useful in children and slim adults and is an excellent technique to improve image contrast in CT angiographic studies. Short spiral scans should be avoided with multislice CT since overranging (extra rotations at the beginning and end of the scan, used for data interpolation) can substantially increase patient dose. Future trends include the introduction of thinner detector rows, wider detector arrays, faster tube rotation, and area detectors than can also be used for fluoroscopy. Noise-reduction techniques and individual dose modulation will gain importance with higher isotropic resolution. Functional and perfusion imaging, as well as advanced image processing and computer-aided diagnosis programs, will add to the possibilities of the next generation of multislice CT scanners.

Gold nanoparticle contrast agents in advanced X-ray imaging technologies

Recently, there has been significant progress in the field of soft- and hard-X-ray imaging for a wide range of applications, both technically and scientifically, via developments in sources, optics and imaging methodologies. While one community is pursuing extensive applications of available X-ray tools, others are investigating improvements in techniques, including new optics, higher spatial resolutions and brighter compact sources. For increased image quality and more exquisite investigation on characteristic biological phenomena, contrast agents have been employed extensively in imaging technologies. Heavy metal nanoparticles are excellent absorbers of X-rays and can offer excellent improvements in medical diagnosis and X-ray imaging. In this context, the role of gold (Au) is important for advanced X-ray imaging applications. Au has a long-history in a wide range of medical applications and exhibits characteristic interactions with X-rays. Therefore, Au can offer a particular advantage as a tracer and a contrast enhancer in X-ray imaging technologies by sensing the variation in X-ray attenuation in a given sample volume. This review summarizes basic understanding on X-ray imaging from device set-up to technologies. Then this review covers recent studies in the development of X-ray imaging techniques utilizing gold nanoparticles (AuNPs) and their relevant applications, including two- and three-dimensional biological imaging, dynamical processes in a living system, single cell-based imaging and quantitative analysis of circulatory systems and so on. In addition to conventional medical applications, various novel research areas have been developed and are expected to be further developed through AuNP-based X-ray imaging technologies.

[Evaluation of over ranging in 64-slice multidetector-row computed tomography examinations for upper abdomen]

64-slice multidetector-row computed tomography (MDCT) have become widely used in recent years, but there is a possibility that a large volume of dose is radiated at the outside of the scope of scanning due to the effect of over ranging (OR). In this research, the dose volume change at the outside of the scope of scanning in the case of X-ray beam width (BW) and pitch factor (PF) is measured, and the effect of BW and PF on OR is considered. We scanned the upper abdomen of an acrylic human phantom using 64-slice multidetector-row CT in 4 conditions while changing BW and PF. We then measured the dose volume absorbed in the breasts, ovary, uterus, and the dose profile on the surface of phantom. As a result, when BW and PF are increased, the dose volume radiated at the outside of the scope of scanning increased, and the effect of OR appeared. Therefore, when BW and PF are set, X-ray radiated at the outside of the scope of scanning should also be considered.

Multi-detector CT angiographic imaging in the follow-up of patients after endovascular abdominal aortic aneurysm repair (EVAR)

BACKGROUND

Multidetector computed tomography (MDCT) angiography represents the standard of reference in the follow-up of patients after endovascular abdominal aortic aneurysm repair (EVAR), being effective in the detection of the full spectrum of possible complications on both axial and 3D images.

METHODS

The purpose of this article is to review the normal CT angiography findings of the different types of stent-grafts and to describe the radiological findings of early and late complications after EVAR on axial and reconstructed images. A selection of cases of post-EVAR MDCT angiography is presented to learn the techniques most commonly used for endovascular treatment, the correct CT scanning technique to acquire the data, the full gamut of possible procedure-related complications and how these complications usually appear on CT images.

CONCLUSION

MDCT angiography is an effective and specific technique in both the pre- and postoperative settings of EVAR procedures. A better understanding of the procedure, the devices, the normal postoperative imaging features and the possible procedure-related complications ensures optimal planning and follow-up of patients undergoing an EVAR procedure.

Neuroradiology back to the future: brain imaging

The beginning of neuroradiology can be traced to the early 1900s with the use of skull radiographs. Ventriculography and pneumoencephalography were introduced in 1918 and 1919, respectively, and carotid angiography, in 1927. Technical advances were made in these procedures during the next 40 years that lead to improved diagnosis of intracranial pathology. Yet, they remained invasive procedures that were often uncomfortable and associated with significant morbidity. The introduction of CT in 1971 revolutionized neuroradiology. Ventriculography and pneumoencephalography were rendered obsolete. The imaging revolution continued with the advent of MR imaging in the early 1980s. Noninvasive angiographic techniques have curtailed the use of conventional angiography, and physiologic imaging gives us a window into the function of the brain. In this historical review, we will trace the origin and evolution of the advances that have led to the quicker, less invasive diagnosis and resulted in more rapid therapy and improved outcomes.

Diagnostic approach to peripheral arterial disease

This article discusses diagnostic imaging techniques used in the evaluation and management of patients with peripheral arterial disease (PAD). Along with a complete vascular examination, noninvasive physiologic testing is used for the initial evaluation of patients with suspected PAD. Duplex ultrasonography provides information on the degree of stenosis or occlusion within a vessel and allows assessment of the vessel wall and plaque morphology. Angiographic imaging techniques should be reserved for determining the optimal endovascular or surgical approach for patients requiring revascularization. Together, all available diagnostic modalities contribute to successful evaluation and management of patients with PAD.

Sonographic Evaluation of Aortic Endografts

The selective use of endovascular devices to repair abdominal aortic aneurysms was introduced in the early 1990s. Although placement of an aortic endograft offers patients a less morbid alternative to surgical repair, this procedure is not without complications. Persistent perfusion of the residual aneurysmal sac via endoleaks may place the patient at risk for aneurysmal enlargement and subsequent rupture. Historically, serial computed tomographic angiography has been used as the primary modality for assessment of aortic endografts. In recent years, sonography has been shown to provide a valued tool for ongoing surveillance of aortic endografts and identification of endoleaks, increasing aneurysmal size, hemodynamic disorders, and graft migration and/or kinking. Standardization of the sonographic evaluation yields accurate information vital to the long-term patency of these conduits.

Peripheral artery disease: current insight into the disease and its diagnosis and management

Peripheral artery disease (PAD), which comprises atherosclerosis of the abdominal aorta, iliac, and lower-extremity arteries, is underdiagnosed, undertreated, and poorly understood by the medical community. Patients with PAD may experience a multitude of problems, such as claudication, ischemic rest pain, ischemic ulcerations, repeated hospitalizations, revascularizations, and limb loss. This may lead to a poor quality of life and a high rate of depression. From the standpoint of the limb, the prognosis of patients with PAD is favorable in that the claudication remains stable in 70% to 80% of patients over a 10-year period. However, the rate of myocardial infarction, stroke, and cardiovascular death in patients with both symptomatic and asymptomatic PAD is markedly increased. The ankle brachial index is an excellent screening test for the presence of PAD. Imaging studies (duplex ultrasonography, computed tomographic angiography, magnetic resonance angiography, catheter-based angiography) may provide additional anatomic information if revascularization is planned. The goals of therapy are to improve symptoms and thus quality of life and to decrease the cardiovascular event rate (myocardial infarction, stroke, cardiovascular death). The former is accomplished by establishing a supervised exercise program and administering cilostazol or performing a revascularization procedure if medical therapy is ineffective. A comprehensive program of cardiovascular risk modification (discontinuation of tobacco use and control of lipids, blood pressure, and diabetes) will help to prevent the latter.

Multidetector-row CT Angiography of Lower Extremities: Usefulness in the Diagnosis of and Intervention for Peripheral Arterial Disease

CT angiography (CTA) based on the data acquired by multidetector-row CT (MDCT) is an established, minimally invasive modality for imaging peripheral arteries. CTA has been used to assess peripheral arterial disease before treatment, and it has replaced conventional angiography for the diagnostic evaluation of peripheral arteries. MDCT can optimize both the long scan length and spatial resolution. CTA using MDCT depicts the fine structures of vessels. Recently, automated CTA analysis software has been developed for measurement of the vascular lumen. The software can automatically measure the diameters of short axial sections at the post-processing workstation. Measurement of the vascular lumen is useful in the planning of intravascular treatment for peripheral arterial disease. CTA is also utilized in assessing the intravascular lumen after metallic stent placement.

Distal abdominal aortic thrombosis diagnosed by three-dimensional contrast-enhanced magnetic resonance angiography

Contrast enhanced magnetic resonance angiography (MRA) can provide noninvasive relatively rapid three-dimensional high-detailed vascular images over large anatomic areas. There are few descriptions of the use of contrast-enhanced MRA in veterinary patients. This is a report illustrating the use of contrast-enhanced MRA to localize the full extent of distal aortic, external iliac, and femoral artery thrombi confirmed surgically in four dogs. Distal aorta contrast-enhanced MRA was anatomically accurate in detecting the full extent of thrombi involving the aorta, external iliac and femoral arteries in these four canine patients. This procedure can provide important information for surgery.

Comparison between 64-row CT angiography and digital subtraction angiography in the study of lower extremities: personal experience

PURPOSE

This study was undertaken to evaluate the potential of 64-row multislice computed tomography (CT) versus digital subtraction angiography (DSA) in detecting significant lesions of lower-extremity inflow and runoff arteries.

MATERIALS AND METHODS

Fifty-three patients underwent 64-row multislice CT and DSA over a mean of 36 days. The vascular tree was divided into 33 segments. Three readers independently reviewed the axial CT scans and multiplanar oblique and two- and three-dimensional reconstructions (maximum intensity projection and volume rendering) images to assess degree of stenosis according to four categories: 1 (0%-49% stenosis); 2 (50%-99% stenosis); 3 (occluded); 4 (not evaluable). In all cases, DSA was performed by arterial catheterisation.

RESULTS

In 53 patients, 1,440 segments were evaluated (infrarenal aorta and 16 arterial segments for each leg; 42 bilateral studies, 11 unilateral studies). Compared with DSA, CT angiography yielded 97.2% sensitivity, 97% specificity, 92.5% positive predictive value, 98.9% negative predictive value, 97.1% diagnostic accuracy and 95.4% concordance on the degree of stenosis.

CONCLUSIONS

Sixty-four-row multislice CT proved to be helpful in detecting haemodynamically significant lesions in peripheral arterial occlusive disease and improved the results obtained with 4- and 16-slice multidetector CT. In addition, owing to the high spatial resolution and rigorous technique, no variations in the data obtained below the knee were detected, overcoming a limitation of earlier generations of CT scanners.

Value of MDCT angiography in developing treatment strategies for critical limb ischemia

OBJECTIVE

The purpose of this study was to assess the value of MDCT angiography in the development of strategies for the treatment of patients with critical limb ischemia.

MATERIALS AND METHODS

During a 12-month period, 150 patients were referred to our department for CT angiography of the peripheral arteries. All patients (n = 28) with clinical stage IV peripheral arterial occlusive disease were included in this retrospective study. The treatment reports, discharge summaries, and follow-up examinations were reviewed to ascertain the number of patients correctly treated on the basis of the CT angiographic findings.

RESULTS

After CT angiography, endovascular treatment was indicated for eight patients, surgical revascularization for four patients, and a combined endovascular and surgical approach for two patients. That the correct treatment decision had been made in all 14 cases was confirmed on the basis of successful endovascular or surgical revascularization. In eight patients, medical treatment was indicated, and one patient underwent amputation at the level of the thigh. Five patients were referred for complementary digital subtraction angiography, but no additional findings were made. During follow-up, three of the original 28 patients were in grave general condition and died within 7 weeks after CT angiography. Thirteen patients needed no additional treatment during the follow-up period through January 2008. After a median treatment-free interval of 381 days, 12 patients underwent additional revascularization because of clinical progression of disease.

CONCLUSION

MDCT angiographic findings lead to accurate recommendations for the management of critical limb ischemia. Thus CT angiography seems to be an important technique for the management of stage IV peripheral arterial occlusive disease in patients without absolute contraindications to CT angiography.

Optimization of the scan protocol for the reduction of diaphragmatic motion artifacts depicted on CT angiography: a phantom study simulating pediatric patients with free breathing

Objective

This study was designed to optimize the scan protocol of CT angiography to reduce diaphragmatic motion artifacts in pediatric patients with free-breathing.

Materials and Methods

A phantom with twelve tubes with different diameters was constructed. To simulate free-breathing, the phantom was connected to a motor, and the phantom moved along the axis of scan. Scans were performed under several conditions: different pitch (1, 1.5) and gantry rotation time (0.37 and 0.75 sec), and different movement range (1 cm, 3 cm) and rates (20/min, 40/min). For CT scanning, a 16-channel CT scanner was used and fixed factors of the CT protocol were as follows: 100 effective mAs, 80 kVp, reconstruction with a soft-algorithm, beam collimation 16×75 mm, reconstruction thickness of 1 mm, and an interval of 0.5 mm. CT scans were repeated five times. Each tube was evaluated with the use of a grading system (0 for images where tubes were not discriminable and 2 for images where tubes were clearly discriminable).

Results

A higher pitch and shorter gantry rotation time produced images with a higher grade. Average grades for the higher pitch (1.5) and faster gantry rotation time (0.37 sec) for each combination of movement were as follows: 1.94 (range 1 cm and rate 20/min), 1.42 (range 1 cm and rate 40/min), 0.86 (range 3 cm and rate 20/min) and 0.52 (range 3 cm and rate 40/min). Average grades for the lower pitch (1) and slower gantry rotation time (0.75 sec) for each combination of movement were 1.08, 0.56, 0.32 and 0.08, respectively.

Conclusion

The scanning speed and especially the pitch are important parameters for CT scans to overcome a respiratory motion artifact.

Multidetector row CT angiography in spontaneous lobar intracerebral hemorrhage: a prospective comparison with conventional angiography

BACKGROUND AND PURPOSE

The aim of our study was to assess the accuracy of multidetector row CT angiography (MDCTA) in the detection of the underlying vascular abnormalities causing spontaneous lobar intracerebral hemorrhage (ICH) compared with conventional digital subtraction angiography (DSA).

MATERIALS AND METHODS

Seventy-eight patients who underwent MDCTA with use of a 16-detector row scanner and DSA were prospectively included in this study. Each study was assessed by 2 independent blinded neuroradiologists; decisions were made in consensus. Findings on CT angiograms, including the original axial data, multiplanar reformations, and volume-rendered images with and without automated bone segmentation, were used to identify the underlying causes of ICH.

RESULTS

Twenty-two of the 78 patients (28.2%) exhibited angiographic abnormalities, including aneurysms of the proximal arteries (n = 9), arteriovenous malformations (n = 7), Moyamoya disease (n = 4), and aneurysms of the distal arteries (n = 2). MDCTA detected the underlying vascular abnormalities in 21 patients except 1 case of small arteriovenous malformation. Overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MDCTA for detection of underlying vascular abnormalities were 95.5%, 100%, 100%, 98.2%, and 98.7%, respectively.

CONCLUSIONS

MDCTA is a highly accurate imaging technique in the diagnosis of underlying vascular abnormalities in patients with spontaneous lobar ICH.

Atherosclerotic Peripheral Vascular Disease Symposium II: vascular magnetic resonance and computed tomographic imaging

Over the past 10 years, there has been a rapid adoption of new technology that has allowed us to image the vascular system in a noninvasive manner with greater speed and improved resolution. The “gold standard,” catheter-based angiography, is now more often used with therapeutic interventions rather than purely diagnostic studies. Catheter-based angiography is being replaced by computerized tomographic angiography (CTA) and magnetic resonance angiography (MRA) for carotid, renal, and peripheral vascular diagnostic examinations. The goal of this writing group is to review the evidence-based approach to selection of imaging modalities; however, regional availability and expertise are recognized as important factors in the selection of imaging modalities.

Multislice CT angiography in the follow-up of fenestrated endovascular grafts: effect of slice thickness on 2D and 3D visualization of the fenestration stents

PURPOSE

To investigate the effect of multislice computed tomography (CT) protocols on the visualization of target vessel stents in patients with abdominal aortic aneurysm (AAA) treated with fenestrated endovascular grafts.

METHODS

Twenty-one patients (19 men; mean age 75 years, range 63-86) undergoing fenestrated endovascular repair of AAA were retrospectively studied. Multislice CT angiography was performed with several protocols, and the section thicknesses used in each were compared to identify any relationship between slice thickness and target vessel stents visualized on 2-dimensional (2D) axial, multiplanar reformatted (MPR), and 3-dimensional (3D) virtual intravascular endoscopy (VIE) images. Image quality was assessed based on the degree of artifacts and their effect on the ability to visualize the configuration, intra-aortic location, and intraluminal appearance of the target vessel stents and measure their protrusion into the aortic lumen.

RESULTS

There were 7 different multislice CT scanning protocols employed in the 21 patients (25 datasets, with 2 sets of follow-up images in 4 patients). The slice thicknesses and numbers (n) of studies included were 0.5 (n=3), 0.625 (n=6), 1.0 (n=1), 1.25 (n=9), 2.5 (n=3), 3.0 (n=1), and 5.0 mm (n=2). Of these CT protocols, images (especially 2D/3D reconstructions) acquired at 2.5, 3.0, and 5.0 mm were significantly compromised by interference from artifacts. Images acquired with a slice thickness of 1.0 or 1.25 mm were scored equal to or lower than those acquired with a submillimeter section thickness (0.5 or 0.625 mm), with minor degrees of artifacts resulting in acceptable image quality.

CONCLUSION

Visualization of the target vessel stents depends on the appropriate selection of multislice CT scanning protocols. Our results showed that studies performed with a slice thickness of 1.0 or 1.25 mm produced similar image quality to those with a thickness of 0.5 or 0.625 mm. Submillimeter slices are not recommended in imaging patients treated with fenestrated stent-grafts, as they did not add additional information to the visualization.

Assessment of aortic pathology and peripheral arterial disease using multidetector computed tomographic angiography

The development of multidetector computed tomography represents a remarkable diagnostic advancement because this imaging modality has been widely used in the evaluation of the cardiovascular system. With scanner-adjusted image acquisition and contrast medium administration, multidetector computed tomographic angiography provides a cost-effective and accurate imaging assessment in patients with aortic pathologies or peripheral arterial occlusive disease. Multidetector computed tomographic angiography is associated with several advantages, including high image spatial resolution and rapid imaging acquisition speed. This diagnostic methodology allows accurate detection of a variety of intravascular lesions in the carotid artery, thoracic and abdominal aorta, renal arteries, and peripheral arterial systems. This article provides an overview of multidetector computed tomographic angiography in the assessment of arterial disease and reviews current literature about this diagnostic technology in the evaluation of aortic and peripheral arterial pathologies.

[Multislice CT angiography in the study of aneurysm of the abdominal aorta: comparison of three different volumes of contrast agent]

OBJECTIVE

To prospectively and quantitatively compare the use of different volumes of contrast in 16-slice CT angiography for the study of aneurysms of the abdominal aorta before and/or after treatment.

MATERIAL AND METHODS

From November 2005 to March 2006, we included 63 consecutive patients referred for CT angiography for aneurysm of the abdominal aorta or for post-treatment follow-up. Each patient was randomly assigned to one of three groups: group A was administered 100 mL of contrast agent, group B 80 mL, and group C 60 mL. In all cases, contrast was administered with 40 mL of physiological serum at a rate of 4 ml/s. A 16-detector CT scanner was used. In the last 61 patients, attenuation was measured in different locations using circular ROIs. Hounsfield units were recorded in the first slice (initial contrast), in the last slice (final contrast), at their maximum value, and also at one-second intervals.

RESULTS

No statistically significant differences in the Hounsfield units recorded in the first slice, in the last slice, or in the maximum values were found between the different groups. Mean values were above 200 in 58 of 61 patients. Weight and body mass index (BMI) were negatively correlated with aortoiliac attenuation.

CONCLUSION

Using a 16-detector CT scanner enables the volume of contrast for studies of aneurysms of the abdominal aorta to be reduced considerably; however, 60 mL might not be sufficient for patients with high weight or BMI.

Determination of the recipient vessels in the head and neck using multislice spiral computed tomography angiography before free flap surgery: a preliminary study

Preoperative assessment of the recipient vessels in free flap surgery directly affects the success rate of the operation by determining the flap type, pedicle length, orientation to the recipient site, and need for a vein graft. For this purpose, conventional angiographic methods are still being used with some disadvantages. The aims of this study were to evaluate the potential success of multislice computed tomography angiography in assessment of the recipient vessels before free flap surgery and to reveal if this may be an alternative to conventional angiography. The study was bilaterally carried out in 33 outpatients using a 16-detector spiral computed tomography scanner. In images of multiplanar reconstructions, maximum intensity projections, and three-dimensional volume renderings, the external carotid artery and its main branches were evaluated in terms of availability; patency, stenosis, or occlusion; maximal and minimal external diameters through their traces; variations involving ramification from another main vessel; and abnormal course. The superior thyroid artery was absent bilaterally in two patients (6.06%). The external carotid artery was stenotic on one side in two patients (6.06%) and on each side in one (3.03%). All the remaining vessels appeared without stenosis, occlusion, or variation. We think that multislice computed tomography angiography can provide detailed information about vascular structures and the remaining anatomic structures and their relationships with the recipient vessels. Therefore, multislice computed tomography angiography, as a less invasive vascular imaging method, can be a useful tool before planning free flap surgery.

Current state of dynamic imaging in endovascular aortic aneurysm repair

Dynamic imaging, in which the time dimension has a specific function in data (image) interpretation, is becoming increasingly important when contemplating endovascular aneurysm repair. Clinical parameters and complications, including proper sizing, successful aneurysm sac exclusion, optimal stent-graft design, endoleaks, graft migration, and stent fracture are beginning to be better understood through dynamic magnetic resonance, ultrasound, and dynamic computed tomography. The current practice using static 3-dimensional reconstructions for the planning and follow-up of aortic aneurysm endograft treatment will most likely evolve, and the use of dynamic aortic imaging will continue to increase. Validation of these imaging modalities in larger scale trials is needed.

A study of multi-detector row CT scan on greater omentum in 50 individuals: correlating with anatomical basis and clinical application

BACKGROUND

In view of the descriptions of the CT manifestations on the greater omentum (GO) were not precise and detailed enough in the previous literature, we tried to evaluate the radiologic-anatomical features of the GO and to address the related clinical implications for the radiologic diagnosis and surgical application.

METHODS

We evaluated the GO by using multi-detector row CT (MDCT) scanning in 50 individuals correlating with anatomical basis and clinical application. Emphasis was placed on the following items: the anatomical distribution and location of the GO; the CT manifestations of the vasculature, fatty tissue and lymph nodes.

RESULTS

The gastro-epiploic vessel, the landmark for delineating the GO, was visualized in 50/50 cases (100%). The gastro-colic vein was detected in 34/50 cases (68%). The free-hanging portion, 48 cases revealed, seemed to have the capability of 'migration': it is located in the subphrenic spaces in 9/48 cases (19%) and distributed in the right lower quadrant predominantly in 10/48 cases (21%). Three-dimensional reformatted images, obtained in five cases, demonstrated the return of the gastro-epiploic vein distinctly. Lymph nodes were rarely detected within the GO.

CONCLUSION

The depicted omental vessels, visualized by using multi-planar reconstruction images together with three-dimensional reformatted images, played a crucial role in delineating the GO comprehensively. It can provide the valuable data for the radiologic diagnosis and surgical therapy planning including surgery of reconstruction, pancreas, portal hypertension as well as infections and neoplastic diseases.

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.

Effect of MDCT angiographic findings on the management of intermittent claudication

OBJECTIVE

The purpose of this study was to assess the reliability of treatment decisions based on MDCT angiographic findings of stage IIb peripheral arterial occlusive disease (PAOD).

MATERIALS AND METHODS

Fifty-eight patients with stage IIb PAOD underwent CT angiography of the abdominal aorta and runoff vessels for further treatment planning. Treatment reports, discharge summaries, and follow-up examinations were reviewed to determine the number of treatments correctly planned on the basis of CT angiographic findings.

RESULTS

On the basis of CT angiographic findings, endovascular treatment was indicated for 18 patients, surgical revascularization for nine patients, and a combined endovascular and surgical approach for two patients. Conservative treatment was indicated for 29 patients. On the basis of successful revascularization, the correctness of the treatment decision was confirmed in all but one patient (n = 28). The treatment plan was modified for one patient referred for surgical revascularization. In that patient, stenosis of the common femoral artery had been overlooked on CT angiography. Patients for whom conservative management was indicated on the basis of CT angiographic findings (n = 29) had a mean follow-up period of 501 days without needing revascularization treatment. This result was defined as indirect confirmation of the accuracy of the decision made with CT angiography.

CONCLUSION

The findings on MDCT angiography led to correct treatment recommendations for patients with claudication. Thus, CT angiography should be used in the management of PAOD.

Multislice CT angiography in abdominal aortic aneurysm treated with endovascular stent grafts: evaluation of 2D and 3D visualisations

Endovascular repair of abdominal aortic aneurysms has been introduced into the clinical practice for more than a decade and has been confirmed to be an effective alternative to conventional open surgery, especially in patients with co-morbid medical conditions. Helical CT angiography is the preferred imaging method in the follow-up of endovascular repair. Recent introduction of multislice CT scanners has augmented its diagnostic role in this area. Diagnostic value of multlislice CT has been complemented by a series of 3D post-processings, which assist vascular surgeons in accurately assessing the effect of endovascular repair by providing additional information when compared to conventional 2D axial images. These reconstructions include multiplanar reformation, curved multiplanar reconstruction, shaded surface display, maximum intensity projection, volume rendering and virtual endoscopy. This article aims to demonstrate the generation of these 2D/3D reconstructions based on multislice CT data acquired from a group of patients with abdominal aortic aneurysm following endovascular repair. A brief introduction of generating each reconstruction was provided; potential clinical applications of each reconstruction were briefly discussed. Images were presented in a dynamic format with the aim of allowing the reader to easily understand the post-processing of these reconstructions.

Preoperative Evaluation of Lower Extremity Arteries for Free Fibula Transfer Using MDCT Angiography

OBJECTIVE

We discuss the preoperative application of computed tomographic (CT) angiography to identify legs suitable for free fibular flaps.

METHODS

The condition of 118 consecutive patients was prospectively evaluated by means of CT angiography for planned free fibula flap reconstructions. We retrospectively investigated whether fibular free flap transfer was performed in candidate patients and whether the presence of postoperative foot ischemia had been followed.

RESULTS

Multidetector row CT angiography demonstrated a normal arterial anatomy in 82 patients, anatomical variants in 30 patients, and peripheral arterial occlusive disease in 6 patients. The radiologists selected 20 legs as major variants that cannot ensure lower extremity viability after flap harvest. Sixty-three patients underwent fibula free flap transfer. The surgeons followed our imaging diagnosis and selected healthy legs as candidates for fibular free transfer in all but 2 patients. No postoperative foot ischemia presented in any patient.

CONCLUSIONS

Computed tomographic angiography is a reliable preoperative imaging technique for the selection of appropriate legs as candidates for fibular free transfer.