ArticlePublisher preview availableLiterature Review

Lower extremity CT angiography in peripheral arterial disease: from the established approach to evolving technical developments

October 2021
The International Journal of Cardiovascular Imaging 37(6)

October 2021
37(6)

DOI:10.1007/s10554-021-02277-1

Authors:

Matthias A Fink

Universität Heidelberg

Show all 11 authorsHide

With the advent of multidetector computed tomography (CT), CT angiography (CTA) has gained widespread popularity for noninvasive imaging of the arterial vasculature. Peripheral extremity CTA can nowadays be performed rapidly with high spatial resolution and a decreased amount of both intravenous contrast and radiation exposure. In patients with peripheral artery disease (PAD), this technique can be used to delineate the bilateral lower extremity arterial tree and to determine the amount of atherosclerotic disease while differentiating between acute and chronic changes. This article provides an overview of several imaging techniques for PAD, specifically discusses the use of peripheral extremity CTA in patients with PAD, clinical indications, established technical considerations and novel technical developments, and the effect of postprocessing imaging techniques and structured reporting.

CTA can differentiate between acute and chronic plaque formation. In acute thromboembolic disease, images show hypodense bulky appearing (noncalcific) plaque with mild surrounding fat stranding, lack of development of collateral circulation, and abrupt cessation of blood flow distally (left panel). In chronic atherosclerotic plaque formation, images show calcified and noncalcified components with deformed vessel lumen, development of collaterals, and reconstitution of distal circulation (right panel)

…

71-year-old woman presenting with moderate to severe claudication (PAD Fontaine stage IIb). Dual-energy run-off CTA was performed on a dual- source CT scanner using 140 and 80 kV. a Maximum intensity projection of the full scan volume provides a first overview, but arteries are partially obscured by overlying bones. b Maximum intensity projection after automatic dual-energy‒based bone removal gives an impression of the location of calcifications, vessel patency, and distal run-off. In particular, a focal high-grade stenosis of the proximal superficial femoral artery (white arrow) followed by a total occlusion (black arrow) and distal reconstitution via collaterals are visualized. c Maximum intensity projection after automatic calcification removal improves the visual impression of vessel patency in areas with calcifications (e.g., the right external iliac artery). d Volume rendering is another visualization technique helpful for an overview of location of calcifications, vessel patency, and distal run-off. For example, a proximal occlusion of the right anterior tibial artery is clearly depicted (arrowhead)

…

Dual-energy run-off CTA on a dual-layer spectral detector CT scanner using 140 kV in a 54-year-old man with intermittent claudication. Depicted are virtual monoenergetic images from 40 to 100 keV at the same window level settings. At lower energy levels, the calf arterial vasculature is better visualized, as the lower energy levels are closer to the k-edge of iodine. Therefore, the iodine contrast is increased. In this example, lower extremity 3-vessel run-off of the bilateral calf is seen, including visualization of the anterior, posterior tibial, and peroneal arteries

…

92-year-old female with a history of percutaneous transluminal angioplasty and stenting in the P1 segment of the right popliteal artery presenting with moderate to severe claudication of the right leg and a small ulcer at the right lateral ankle. Contrast-enhanced MRA was performed. A MRA section of the pelvis and B MIP of the subtracted MRA demonstrate focal high-grade stenosis of the right common femoral artery (thick arrow) and the left common iliac artery (arrow head). C MIP of the subtracted MRA section of the thigh reveals several irregularities of the right superficial femoral and popliteal arteries, in particular a focal stenosis in the P1 segment oat the level of the stent (thin arrow). Note the visualization of the anatomical variant with a high origin of the posterior tibial artery on the right-hand side

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Contrast bolus-tracking method with region of interest (ROI) placed in the proximal abdominal aorta. The Hounsfield units (HU) are measured when the contrast agent injection is initiated. Once the ROI value increases to higher than 150 HU, the actual scan is initiated

…

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Vol.:(0123456789)

1 3

The International Journal of Cardiovascular Imaging (2021) 37:3101–3114

https://doi.org/10.1007/s10554-021-02277-1

REVIEW PAPER

Lower extremity CT angiography inperipheral arterial disease:

fromtheestablished approach toevolving technical developments

OmarShwaiki1· BasemRashwan1· MatthiasA.Fink2· LevesterKirksey3· SameerGadani1·

KarunakaravelKaruppasamy1· ClaudiusMelzig2· DustinThompson1· GiuseppeD’Amico4· FabianRengier2·

SasanPartovi1

Received: 5 March 2021 / Accepted: 3 May 2021 / Published online: 17 May 2021

Abstract

With the advent of multidetector computed tomography (CT), CT angiography (CTA) has gained widespread popularity for

noninvasive imaging of the arterial vasculature. Peripheral extremity CTA can nowadays be performed rapidly with high

spatial resolution and a decreased amount of both intravenous contrast and radiation exposure. In patients with peripheral

artery disease (PAD), this technique can be used to delineate the bilateral lower extremity arterial tree and to determine the

amount of atherosclerotic disease while diﬀerentiating between acute and chronic changes. This article provides an overview

of several imaging techniques for PAD, speciﬁcally discusses the use of peripheral extremity CTA in patients with PAD,

clinical indications, established technical considerations and novel technical developments, and the eﬀect of postprocessing

imaging techniques and structured reporting.

Keywords CT angiography· Peripheral artery disease· Dual-energy CT· Structured reporting

Introduction

Peripheral artery disease (PAD) is deﬁned as partial or com-

plete obstruction of any part of the peripheral arterial tree

and is typically associated with the lower extremities. PAD

represents the third leading cause of atherosclerotic mor-

bidity after coronary heart disease and stroke [1–3]. The

primary etiology associated with PAD is atherosclerosis, a

chronic inﬂammatory disease that leads to plaque forma-

tion, with the most relevant risk factors being advanced age,

smoking, and diabetes. Other well-established risk factors

are hypertension, male sex, Black ethnicity, hyperlipidemia,

and family history [4–7]. PAD has a high prevalence, occur-

ring in roughly one in ten individuals above the age of 55

and in up to one in seven individuals above the age of 70;

the prevalence has also increased over the past few decades,

presumably because of an aging population [3, 5, 6].

Most individuals with PAD are asymptomatic, and analy-

sis of several screening studies have found that the most fre-

quent sites of disease among asymptomatic individuals are

the iliac and femoral arteries, with femoropopliteal disease

being most common [8–10]. Some studies have suggested

that there may be an association between certain risk factors

and the anatomic distribution of disease [11, 12].

In patients with symptomatic PAD, the most common

symptoms are related to demand ischemia, the same process

underlying atherosclerotic manifestations in other parts of

the body. In the abdomen, PAD can manifest as mesenteric

ischemia, which can be diagnosed and treated with meth-

ods similar to those used for lower extremity PAD [13, 14].

Peripherally, PAD symptoms relate to claudication, with

disease progression leading to ulcer formation, impaired

wound healing, and even pain at rest. Routine screening for

PAD in asymptomatic individuals is not typically performed

and is generally reserved for those at high risk of the dis-

ease. The rationale behind not pursuing routine screening

* Sasan Partovi

sxp509@case.edu

1 Department ofInterventional Radiology, Cleveland Clinic

Main Campus, Cleveland, OH, USA

2 Section ofEmergency Radiology, Clinic forDiagnostic

andInterventional Radiology, University Hospital

Heidelberg, Heidelberg, Germany

3 Department ofVascular Surgery, Cleveland Clinic Main

Campus, Cleveland, OH, USA

4 Department ofTransplant Surgery, Cleveland Clinic Main

Campus, Cleveland, OH, USA

Content courtesy of Springer Nature, terms of use apply. Rights reserved.

Low-iodine 40-keV virtual monoenergetic CT angiography of the lower extremities

Article

Full-text available

Oct 2023

Introduction: To evaluate a reduced iodine volume protocol for lower extremity CT angiography (CTA) using dual-energy CT (DECT). Methods: This retrospective study included consecutive patients who underwent lower extremity CTA from June to December 2022. A 10 ml 1:1 mixed test bolus was performed, followed by a 40 ml full bolus at a 2.5/s injection rate, using 400 mg/ml iodine contrast media. Conventional and 40 keV virtual monoenergetic images (VMI) were reconstructed. For both reconstructions, ﬁve main artery segments were assessed with a 3-point image quality score as well as quantitative attenuation, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) measurements with diagnostic quality thresholds (respectively >150 HU and >3). Results: Forty patients were included in the study (mean age 68 ± 12 yo). 200 artery segments were assessed. Median qualitative image scores were 3 [IQR, 3, 3] for both reconstructions. 40 keV VMI upgraded qualitative scores for 51 (26%) of patients, including 9 (5%) from nondiagnostic to diagnostic quality. 40 keV VMI obtained attenuation and CNR diagnostic quality for respectively 100% and 100% of segments, compared with 96% and 98% for conventional images (p < 0.001). Distal artery segments showed the most differences between 40 keV VMI and conventional images. Conclusion: A low-iodine lower extremity CTA protocol is feasible, with 40 keV virtual monoenergetic spectral reconstruction enabling maintained diagnostic image quality at the distal artery segments.

Association of lower extremity peripheral arterial disease with quantitative muscle features from computed tomography angiography

Article

Full-text available

Mar 2024

Objectives To explore the association between lower extremity muscle features from CTA and peripheral arterial disease (PAD) severity using digital subtraction angiography (DSA) as reference standard. Methods Informed consent was waived for this Institutional Review Board approved retrospective study. PAD patients were recruited from July 2016 to September 2020. Two radiologists evaluated PAD severity on DSA and CTA using runoff score. The patients were divided into two groups: mild PAD (DSA score ≤ 7) vs. severe PAD (DSA score > 7). After segmenting lower extremity muscles from CTA, 95 features were extracted for univariable analysis, logistic regression model (LRM) analysis, and sub-dataset analysis (PAD prediction based on only part of the images). AUC of CTA score and LRMs for PAD prediction were calculated. Features were analyzed using Student’s t test and chi-squared test. p < 0.05 was considered statistically significant. Results A total of 56 patients (69 ± 11 years; 38 men) with 56 lower legs were enrolled in this study. The lower leg muscles of mild PAD group (36 patients) showed higher CT values (44.6 vs. 39.5, p < 0.001) with smaller dispersion (35.6 vs. 41.0, p < 0.001) than the severe group (20 patients). The AUC of CTA score, LRM-I (constructed with muscle features), and LRM-II (constructed with muscle features and CTA score) for PAD severity prediction were 0.81, 0.84, and 0.89, respectively. The highest predictive performance was observed in the image subset of the middle and inferior segments of lower extremity (LRM-I, 0.83; LRM-II, 0.90). Conclusions Lower extremity muscle features are associated with PAD severity and can be used for PAD prediction. Critical relevance statement Quantitative image features of lower extremity muscles are associated with the degree of lower leg arterial stenosis/occlusion and can be a beneficial supplement to the current imaging methods of vascular stenosis evaluation for the prediction of peripheral arterial disease severity. Key points • Compared with severe PAD, lower leg muscles of mild PAD showed higher CT values (39.5 vs. 44.6, p < 0.001). • Models developed with muscle CT features had AUC = 0.89 for predicting PAD. • PAD severity prediction can be realized through the middle and inferior segment of images (AUC = 0.90). Graphical Abstract

Sarcopenia in peripheral arterial disease: Establishing and validating a predictive nomogram based on clinical and computed tomography angiography indicators

Article

Full-text available

Mar 2024

Purpose To establish, validate, and clinically evaluate a nomogram for predicting the risk of sarcopenia in patients with peripheral arterial disease (PAD) based on clinical and lower extremity computed tomography angiography (LE-CTA) imaging characteristics. Methods Clinical data and CTA imaging features from 281 PAD patients treated between January 1, 2019, and May 1, 2023, at two hospitals were retrospectively analyzed using binary logistic regression to identify the independent risk factors for sarcopenia. These identified risk factors were used to develop a predictive nomogram. The nomogram's effectiveness was assessed through various metrics, including the receiver operating characteristic (ROC) curve, area under the curve (AUC), concordance index (C-index), Hosmer-Lemeshow (HL) test, and calibration curve. Its clinical utility was demonstrated using decision curve analysis (DCA). Results Several key independent risk factors for sarcopenia in PAD patients were identified, namely age, body mass index (BMI), history of coronary heart disease (CHD), and white blood cell (WBC) count, as well as the severity of luminal stenosis (P < 0.05). The discriminative ability of the nomogram was supported by the C-index and an AUC of 0.810 (95% confidence interval: 0.757–0.862). A robust concordance between predicted and observed outcomes was reflected by the calibration curve. The HL test further affirmed the model's calibration with a P-value of 0.40. The DCA curve validated the nomogram's favorable clinical utility. Lastly, the model underwent internal validation. Conclusions A simple nomogram based on five independent factors, namely age, BMI, history of CHD, WBC count, and the severity of luminal stenosis, was developed to assist clinicians in estimating sarcopenia risk among PAD patients. This tool boasts impressive predictive capabilities and broad utility, significantly aiding clinicians in identifying high-risk individuals and enhancing the prognosis of PAD patients.

The Clinical Utility of Lower Extremity Dual-Energy CT Angiography in the Detection of Bone Marrow Edema in Diabetic Patients with Peripheral Artery Disease

Article

Full-text available

Mar 2024

(1) Background: Type 2 diabetes is a major cause of incidences and the progression of peripheral artery disease (PAD). Bone marrow edema (BME) is an important finding suggestive of underlying bone inflammation in non-traumatic diabetic patients with PAD. Our aim was to evaluate the presence, severity, and clinical implications of BME detected by virtual non-calcium application (VNCa) of dual-energy CT angiography (DE-CTA). (2) Methods: A consecutive series of 76 diabetic patients (55 men; mean age 71.6 ± 11.2 yrs) submitted to lower limb DE-CTA for PAD evaluation and revascularization planning, which were retrospectively analyzed. VNCa images were independently and blindly revised for the presence, location, and severity of BME by two radiologists with 10 years of experience. BME and non-BME groups were evaluated in terms of PAD clinical severity and 6-month secondary major amputation rate. (3) Results: BME was present in 17 (22%) cases, while 59 (78%) patients were non-BME. The BME group showed a significantly higher incidence of major amputation (p < 0.001) and a significantly higher number of patients with advanced clinical stages of PAD compared to the non-BME group (p = 0.024). (4) Conclusions: Lower limb DE-CTA with VNCa application is a useful tool in the detection of BME in diabetic patients with PAD, simultaneously enabling the evaluation of the severity and location of the arterial disease for revascularization planning. BME presence could be a marker of clinically severe PAD and a possible risk factor for revascularization failure.

USING A SIMULATED CASE, HOW TO EVALUATE AND TREAT VENOUS VASCULAR LESIONS OF THE LOWER LIMBS

Article

Feb 2024

Background: Venous vascular lesions in the lower extremities pose a significant clinical challenge due to their varied etiology and complexity. Practical assessment and management of these lesions require a thorough understanding of their underlying causes and appropriate treatment modalities. Objective: Using a simulated case study approach, this research paper will comprehensively analyze assessment and management strategies for venous vascular lesions in the lower extremities. By employing this method, the paper seeks to enhance healthcare professionals' knowledge and decision-making capabilities in diagnosing and treating venous vascular issues. Methods: The paper utilizes a simulated case study format to explore assessment and management strategies for venous vascular lesions in the lower extremities. Through an in-depth analysis of a representative case, various diagnostic techniques, treatment options, and therapeutic interventions are discussed and evaluated. Results: The simulated case study highlights the diverse etiology and complexity of venous vascular lesions in the lower extremities. Assessment strategies encompass clinical examination, imaging studies, and diagnostic procedures tailored to identify the underlying pathology. Management approaches, including conservative measures, minimally invasive interventions, and surgical techniques, are discussed in detail, considering the individual patient's needs and preferences. Conclusion: By employing a simulated case study approach, this paper provides valuable insights into assessing and managing venous vascular lesions in the lower extremities. Healthcare professionals can utilize the knowledge gained from this analysis to improve their diagnostic accuracy and optimize treatment outcomes for patients with venous vascular issues. Background: Venous vascular lesions in the lower extremities pose a significant clinical challenge due to their varied etiology and complexity. Practical assessment and management of these lesions require a thorough understanding of their underlying causes and appropriate treatment modalities. Objective: Using a simulated case study approach, this research paper will comprehensively analyze assessment and management strategies for venous vascular lesions in the lower extremities. By employing this method, the paper seeks to enhance healthcare professionals' knowledge and decision-making capabilities in diagnosing and treating venous vascular issues. Methods: The paper utilizes a simulated case study format to explore assessment and management strategies for venous vascular lesions in the lower extremities. Through an in-depth analysis of a representative case, various diagnostic techniques, treatment options, and therapeutic interventions are discussed and evaluated. Results: The simulated case study highlights the diverse etiology and complexity of venous vascular lesions in the lower extremities. Assessment strategies encompass clinical examination, imaging studies, and diagnostic procedures tailored to identify the underlying pathology. Management approaches, including conservative measures, minimally invasive interventions, and surgical techniques, are discussed in detail, considering the individual patient's needs and preferences. Conclusion: By employing a simulated case study approach, this paper provides valuable insights into assessing and managing venous vascular lesions in the lower extremities. Healthcare professionals can utilize the knowledge gained from this analysis to improve their diagnostic accuracy and optimize treatment outcomes for patients with venous vascular issues.

SpeckleCam: high-resolution computational speckle contrast tomography for deep blood flow imaging

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Sep 2023

Laser speckle contrast imaging is widely used in clinical studies to monitor blood flow distribution. Speckle contrast tomography, similar to diffuse optical tomography, extends speckle contrast imaging to provide deep tissue blood flow information. However, the current speckle contrast tomography techniques suffer from poor spatial resolution and involve both computation and memory intensive reconstruction algorithms. In this work, we present SpeckleCam, a camera-based system to reconstruct high resolution 3D blood flow distribution deep inside the skin. Our approach replaces the traditional forward model using diffuse approximations with Monte-Carlo simulations-based convolutional forward model, which enables us to develop an improved deep tissue blood flow reconstruction algorithm. We show that our proposed approach can recover complex structures up to 6 mm deep inside a tissue-like scattering medium in the reflection geometry. We also conduct human experiments to demonstrate that our approach can detect reduced flow in major blood vessels during vascular occlusion.

SpeckleCam: High-resolution Computational Speckle Contrast Tomography for Deep Blood Flow Imaging

Preprint

Aug 2023

CT angiography of the lower limbs: combining small field of view with large matrix size and iterative reconstruction further improves image quality of below-the-knee arteries

Article

Jun 2024
ACTA RADIOL

Background Image quality and diagnostic accuracy in computed tomography angiography (CTA) reach their limits in imaging of below-the-knee vessels. Purpose To evaluate whether image quality in CTA of lower limbs is further improvable by combining side-separate reconstruction with a larger matrix size and whether resulting noise can be compromised with iterative reconstruction (IR). Material and Methods From CTA of the lower extremities of 26 patients (5 women, 21 men; mean age = 68.5 ± 10.3 years), the lower legs were reconstructed side-separately with different reconstruction algorithms and matrix sizes including filtered back projection (FBP) with a 512 × 512 matrix, FBP with a 1024 × 1024 matrix, IR (SAFIRE) with a 512 × 512 matrix, and IR (SAFIRE) with a 1024 × 1024 matrix. A total of 208 CT series were evaluated. Subjective image quality was assessed by two readers using a 5-point Likert scale. Image noise was assessed by measuring signal-to-noise and contrast-to-noise ratios. Results Subjective image quality was rated significantly higher when using a 1024 × 1024 matrix ( P < 0.001) and could further be increased with IR. Vessel sharpness was rated significantly better with a larger matrix ( P < 0.001). Visible and measured image noise was significantly higher with a 1024 × 1024 matrix but could be reduced by using IR ( P < 0.001), even to a level below FBP with a 512 × 512 matrix while reconstructing with a larger matrix ( P < 0.001). Conclusion Image quality, image noise, and vessel sharpness can be further improved in CTA of the lower extremities with side-separate reconstruction using a 1024 × 1024 matrix size and IR.

Trends in non-focal neurological chief complaints and CT angiography utilization among adults in the emergency department

Article

Mar 2024
INTERN EMERG MED

Prudent imaging use is essential for cost reduction and efficient patient triage. Recent efforts have focused on head and neck CTA in patients with emergent concerns for non-focal neurological complaints, but have failed to demonstrate whether increases in utilization have resulted in better care. The objective of this study was to examine trends in head and neck CTA ordering and determine whether a correlation exists between imaging utilization and positivity rates. This is a single-center retrospective observational study at a quaternary referral center. This study includes patients presenting with headache and/or dizziness to the emergency department between January 2017 and December 2021. Patients who received a head and neck CTA were compared to those who did not. The main outcomes included annual head and neck CTA utilization and positivity rates, defined as the percent of scans with attributable acute pathologies. Among 24,892 emergency department visits, 2264 (9.1%) underwent head and neck CTA imaging. The percentage of patients who received a scan over the study period increased from 7.89% (422/5351) in 2017 to 13.24% (662/5001) in 2021, representing a 67.4% increase from baseline (OR, 1.14; 95% CI 1.11–1.18; P < .001). The positivity rate, or the percentage of scans ordered that revealed attributable acute pathology, dropped from 16.8% (71/422) in 2017 to 10.4% (69/662) in 2021 (OR, 0.86; 95% CI 0.79–0.94; P = .001), a 38% reduction in positive examinations. Throughout the study period, there was a 67.4% increase in head and neck CTA ordering with a concomitant 38.1% decrease in positivity rate.

Clinical characteristics and risk factors of diabetic foot ulcers with PAD

Article

Dec 2023

Objective: This study aimed to analyze the clinical characteristics of patients with diabetic foot ulcers combined with peripheral arterial disease (PAD) and the risk factors. Patients and methods: A retrospective study was conducted on 120 patients with diabetic foot ulcers in the Second Affiliated Hospital of Dalian Medical University from October 2018 to February 2021. The patients were divided into uncombined with the PAD group (42 cases) and combined with the PAD group (78 cases). The baseline information and clinical indicators were measured from two groups. Univariate and binary logistic regression was used to analyze the risk factors of PAD in patients with diabetic foot ulcers. Results: The proportion of patients with age ≥ 60 years, Wagner grade 4-5 and smoking history in the combined group was higher than that in the uncombined group (p < 0.05). The diastolic blood pressure (DBP) of the combined group was lower than that of the uncombined group, while the C-reactive protein (CRP), neutrophil-to-lymphocyte ratio (NLR) and glycated hemoglobin (HbA1c) levels of the combined group were higher than those of the uncombined group (p < 0.05). Binary logistic regression analysis showed that age ≥ 60 years, high Wagner grade, smoking, elevated CRP, NLR and HbA1c levels were risk factors for patients with diabetic foot ulcer combined with PAD (OR > 1, p < 0.05). An elevated DBP level was the protective factor for PAD in patients with diabetic foot ulcer (OR < 1, p < 0.05). Conclusions: Patients with diabetic foot ulcer combined with PAD have the clinical characteristics of poor blood pressure control, long course of disease, and low ABI value. Age ≥ 60 years, high Wagner grade, smoking history, elevated CRP, NLR and HbA1c levels are the risk factors of PAD in patients with diabetic foot ulcer. Increased DBP is protective for PAD in patients with diabetic foot ulcer.

Image quality and radiation exposure with low-contrast-dose computed tomography angiography of the lower extremities

Article

Full-text available

Apr 2020

Abed H Assi

Introduction: Multidetector computed tomography is the reference standard for the diagnosis of peripheral arterial disease (PAD). The aim of this study is to optimise the image quality of computed tomography (CT) scanning for the diagnosis of PAD with the lowest possible radiation and contrast volume. Material and methods: Seventy-two patients were referred for evaluation of suspected PAD with CT angiography. Patients were randomly assigned to an optimise care dose of kVp - group A, n = 36; 18 men, 18 women; mean age, 63 years with standard deviation 15; range, 20-88 years (contrast volume 80-85 ml was injected automatically with bolus tracking, and group B, n = 36; 18 men, 18 women; mean age, 61 years with standard deviation 16; range, 26-88 years (contrast volume 120-140 ml was injected automatically with bolus tracking). Other scanning parameters were kept constant. Lower extremities vessel enhancement and image noise were quantified, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective vessel contrast was assessed by two radiologists in consensus. Result: A total of 16 cases of PAD (22.2%) were found in the evaluated of subjects (10 in group A, and six in group B).All PAD cases were detected by the two readers. There was no significant difference in the size or location of the PAD between the two groups; the average image noise was 19 HU for group A and 16 HU for group B. The difference was not statistically significant (p = 0.183). Overall, the SNR and CNR were slightly higher in group B (25.5 and 24.1, respectively) compared with group A (20 and 17.4, respectively), but those differences were not statistically significant (p = 061 and p = 0.38, respectively). Conclusions: All patients were evaluated by lower extremities CTA protocol allowing similar image quality to be achieved in both groups, with optimised care dose for both protocols, and contrast volume was reduced by 40% in the new protocol group compared to the conventional protocol group.

CT Angiography in the Lower Extremity Peripheral Artery Disease Feasibility of an Ultra-Low Volume Contrast Media Protocol

Article

Full-text available

May 2018

Purpose: The ALARA principle is not only relevant for effective dose (ED) reduction, but also applicable for contrast media (CM) management. Therefore, the aim was to evaluate the feasibility of an ultra-low CM protocol in the assessment of peripheral artery disease (PAD). Materials and methods: Fifty PAD patients were scanned on third-generation dual-source computed tomography, from diaphragm to the forefoot, as follows: tube voltage: 70 kV, reference effective tube current: 90 mAs, collimation: 192 × 2 × 0.6 mm, with individualized acquisition timing. The protocol ED (mSv) was quantified with dedicated software. CM protocol consisted of 15 ml test bolus and 30 ml main bolus (300 mgI/ml) injected at 5 ml/s, followed by a 40 ml saline chaser at the same flow rate. Aorto-popliteal bolus transit time was used to calculate the overall acquisition time and delay. Objective (hounsfield units-HU; contrast-to-noise ratio-CNR) and subjective image quality (four-point Likert score) were assessed at different anatomical regions from the aorta down to the forefoot. Results: Mean attenuation values were exceeding 250 HU from aorta down to the anterior tibial artery with CNR < 13. However, decline in attenuation was observed in more distal region with mean values of 165 and 199 HU, in left and right dorsalis pedis artery, respectively. Mode subjective image quality from the level of aorta down to the popliteal segment was excellent; below the knee mode score was good. The mean ED per protocol was 1.1 ± 0.5 mSv. Conclusion: Use of an ultra-low CM volume protocol at 70 kV is feasible in the evaluation of PAD, resulting in good to excellent image quality with mean ED of 1.1 ± 0.5 mSv. Level of evidence: Level 3, Local non-random sample.

Duplex Ultrasound as a reliable alternative to CT angiography for treatment planning of Peripheral Artery Disease

Article

Apr 2021
Int Angiol

Background: The aim of this work is to compare the diagnostic accuracy of Duplex ultrasound (DUS) and CT angiography (CTA) in the study of arterial vessels, in patients with chronic peripheral arterial disease (PAD) of the lower limbs to undergo endovascular revascularization with the use of intraprocedural digital angiography (DSA). Methods: 94 patients with obstructive pathology of the arterial axes of the lower limbs were enrolled in the study. In all patients, endovascular revascularization treatment was considered the most suitable therapeutic choice. For this reason, ultrasound and CTA was performed preoperatively in all and based on the data obtained it was decided to classify the arterial tree into five segments: iliac, common femoral, superficial femoral, popliteal and infra-geniculate. According to the degree of stenosis or occlusion, the arteries were scored in no stenotic, stenotic and occluded. The comparison of the data provided by the DUS and the CTA was carried out with reference to the parameters obtained by the DSA. Results: The results of our experience have shown that in the iliac arterial district DUS proved to be less accurate than CT angiography when compared to DSA (Cohen's Kappa agreement of 0.91 and 1.0, respectively). Good diagnostic concordance were found in the femoro-popliteal district (Cohen's Kappa agreement 33 between 0.96 and 0.93). On the contrary, when the data of the infra-geniculate area were compared, CT angiography showed a net deficiency compared to DSA and DUS (Cohen's k: 0.75). Conclusions: Due to its accuracy, high-quality DUS performed by well-trained operators may therefore represent a good alternative to CTA in patients undergoing endovascular revascularization, in order to reduce the use of contrast-enhanced radiological imaging especially when a condition of intolerance to the contrast medium and/or renal insufficiency coexists.

Diagnostic accuracy of non-contrast quiescent-interval slice-selective (QISS) MRA combined with MRI-based vascular calcification visualization for the assessment of arterial stenosis in patients with lower extremity peripheral artery disease

Article

Oct 2020

Objectives The proton density–weighted, in-phase stack-of-stars (PDIP-SOS) MRI technique provides calcification visualization in peripheral artery disease (PAD). This study sought to investigate the diagnostic accuracy of a combined non-contrast quiescent-interval slice-selective (QISS) MRA and PDIP-SOS MRI protocol for the detection of PAD, in comparison with CTA and digital subtraction angiography (DSA).Methods Twenty-six prospectively enrolled PAD patients (70 ± 8 years) underwent lower extremity CTA and 1.5-T or 3-T PDIP-SOS/QISS MRI prior to DSA. Two readers rated image quality and graded stenosis (≥ 50%) on QISS MRA without/with calcification visualization. Sensitivity, specificity, and area under the curve (AUC) were calculated against DSA. Calcification was quantified and compared between MRI and non-contrast CT (NCCT) using paired t test, Pearson’s correlation, and Bland-Altman analysis.ResultsImage quality ratings were significantly higher for CTA compared to those for MRA (4.0 [3.0–4.0] and 3.0 [3.0–4.0]; p = 0.0369). The sensitivity and specificity of QISS MRA, QISS MRA with PDIP-SOS, and CTA for ≥ 50% stenosis detection were 85.4%, 92.2%, and 90.2%, and 90.3%, 93.2%, and 94.2%, respectively, while AUCs were 0.879, 0.928, and 0.923, respectively. A significant increase in AUC was observed when PDIP-SOS was added to the MRA protocol (p = 0.0266). Quantification of calcification showed significant differences between PDIP-SOS and NCCT (80.6 ± 31.2 mm3 vs. 88.0 ± 29.8 mm3; p = 0.0002) with high correlation (r = 0.77, p < 0.0001) and moderate mean of differences (− 7.4 mm3).ConclusionQISS MRA combined with PDIP-SOS MRI provides improved, CTA equivalent, accuracy for the detection of PAD, although its image quality remains inferior to CTA.Key Points • Agreement in stenosis detection rate using non-contrast quiescent-interval slice-selective MRA compared to DSA improved when calcification visualization was provided to the readers. • An increase was observed in both sensitivity and specificity for the detection of ≥ 50% stenosis when MRI-based calcification assessment was added to the protocol, resulting in a diagnostic accuracy more comparable to CTA. • Quantification of calcification showed statistical difference between MRI and non-contrast CT; however, a high correlation was observed between the techniques.

Gadolinium Deposition and Nephrogenic Systemic Fibrosis: A Radiologist’s Primer

Article

Dec 2019

Gadolinium-based contrast agents (GBCAs) have an excellent safety profile. However, over the last 2 decades, two specific concerns have surfaced. GBCAs are associated with nephrogenic systemic fibrosis (NSF) and tissue retention of gadolinium. NSF is a rare fibrosing disorder with a poor prognosis, which is characterized by skin and subcutaneous thickening as well as systemic manifestations. The disease has been reported exclusively in patients with advanced renal disease, and it is associated with higher doses and specific types of GBCAs. The number of new cases of NSF has fallen over the past decade, presumably because of adherence by health care providers to regulatory guidelines, which continue to evolve. While gadolinium retention has been known to occur in the liver and bones, the relatively recent findings of deposition and retention in the brain have reignited the debate concerning the safety profile of GBCAs. Despite these concerns, there have been no proven health effects related to gadolinium deposition and retention other than NSF. The authors review the different categories of GBCAs available for commercial use, discuss NSF and gadolinium retention in the brain, and provide updates on the latest U.S. and European regulatory guidelines regarding use of these agents. Given the frequency with which GBCAs are used in clinical practice, it is imperative for all radiologists to learn the current guidelines to provide the safest and highest quality of patient care. ©RSNA, 2019.

Preprocedural Cross-Sectional Imaging Prior to Percutaneous Peripheral Arterial Disease Interventions

Article

Nov 2019

Preprocedural cross-sectional imaging (PCSI) for peripheral artery disease (PAD) may vary due to patient complexity, anatomical disease burden, and physician preference. The objective of this study was to determine the utility of PCSI prior to percutaneous vascular interventions (PVIs) for PAD. Patients receiving first time lower extremity angiograms from 2013 to 2015 at a single institution were evaluated for PCSI performed within 180 days, defined as computed tomography angiography (CTA) or magnetic resonance angiography (MRA) evaluating abdominal to pedal vasculature. The primary outcome was technical success defined as improving the target outflow vessels to <30% stenosis. Of the 346 patients who underwent lower extremity angiograms, 158 (45.7%) patients had PCSI, including 150 patients had CTA and 8 patients had MRA. Of these, 48% were ordered by the referring provider (84% at an outside institution). Preprocedural cross-sectional imaging was performed at a median of 26 days (interquartile range: 9-53) prior to the procedure. The analysis of the institution’s 5 vascular surgeons identified PCSI rates ranging from 31% to 70%. On multivariate analysis, chronic kidney disease (odds ratio [OR] = 0.35; 95% confidence interval [CI]: 0.17-0.73) was associated with less PSCI usage, and inpatient/emergency department evaluation (OR = 3.20; 95% CI: 1.58-6.50) and aortoiliac disease (OR = 2.78; 95% CI: 1.46-5.29) were associated with higher usage. After excluding 31 diagnostic procedures, technical success was not statistically significant with PSCI (91.3%) compared to without PCSI (85.6%), P = .11. When analyzing 89 femoral–popliteal occlusions, technical success was higher with PCSI (88%) compared to procedures without (69%) P = .026. Our analysis demonstrates that routine ordering of PCSI may not be warranted when considering technical success of PVI; however, PCSI may be helpful in treatment planning. Further studies are needed to confirm these findings in another practice setting, with more prescriptive use of PCSI to improve procedural success, and thereby improve the value of PCSI.

Modified calcium subtraction in dual-energy CT angiography of the lower extremity runoff: impact on diagnostic accuracy for stenosis detection

Article

Feb 2019

Objectives To investigate the diagnostic accuracy of a modified three-material decomposition calcium subtraction (CS) algorithm for the detection of arterial stenosis in dual-energy CT angiography (DE-CTA) of the lower extremity runoff compared to standard image reconstruction, using digital subtraction angiography (DSA) as the reference standard. Methods Eighty-eight patients (53 males; mean age, 65.9 ± 11 years) with suspected peripheral arterial disease (PAD) who had undergone a DE-CTA examination of the lower extremity runoff between May 2014 and May 2015 were included in this IRB-approved, HIPAA-compliant retrospective study. Standard linearly blended and CS images were reconstructed and vascular contrast-to-noise ratios (CNR) were calculated. Two independent observers assessed subjective image quality using a 5-point Likert scale. Diagnostic accuracy for ≥ 50% stenosis detection was analyzed in a subgroup of 45 patients who had undergone additional DSA. Diagnostic accuracy parameters were estimated with a random-effects logistic regression analysis and compared using generalized estimating equations. Results CS datasets showed higher CNR (15.3 ± 7.3) compared to standard reconstructions (13.5 ± 6.5, p < 0.001). Both reconstructions showed comparable qualitative image quality scores (CS, 4.64; standard, 4.57; p = 0.220). Diagnostic accuracy (sensitivity, specificity, positive and negative predictive values) for CS reconstructions was 96.5% (97.5%, 95.6%, 90.9%, 98.1) and 93.1% (98.8%, 90.4%, 82.3%, 99.1%) for standard images. Conclusions A modified three-material decomposition CS algorithm provides increased vascular CNR, equivalent qualitative image quality, and greater diagnostic accuracy for the detection of significant arterial stenosis of the lower extremity runoff on DE-CTA compared with standard image reconstruction. Key Points • Calcified plaques may lead to overestimation of stenosis severity and false positive results, requiring additional invasive digital subtraction angiography (DSA). • A modified three-material decomposition algorithm for calcium subtraction provides greater diagnostic accuracy for the detection of significant arterial stenosis of the lower extremity runoff compared with standard image reconstruction. • The application of this algorithm in patients with heavily calcified vessels may be helpful to potentially reduce inconclusive CT angiography examinations and the need for subsequent invasive DSA.

Radiologist Preferences, Agreement, and Variability in Phrases Used to Convey Diagnostic Certainty in Radiology Reports

Article

Dec 2018
J Am Coll Radiol

Purpose: To understand radiologists' preference and variability in phrases for expressing diagnostic certainty in radiology reports. Materials and methods: This institutional review board-approved study was part of a quality improvement initiative to improve the quality of radiology reports at a tertiary academic hospital. Sixteen phrases commonly used in radiology reports to convey diagnostic certainty were extracted from prior publications. The degree of diagnostic certainty was divided into six arbitrary categories by an expert panel. We used an anonymous online survey to query 239 radiologists at our institution regarding their preferred phrase for each category. We evaluated the distribution of preferred phrases, performed cluster analysis to find groups of phrases used to describe specific diagnostic certainty categories, and calculated Krippendorff's α to evaluate how reliably radiologists use various phrases to express diagnostic certainty. Findings: In all, 59.4% (142 of 239) of radiologists completed the survey. The most commonly preferred phrases were "consistent with" (45.1%; 64 of 142) for 100% confident, "highly suggestive of" (46.5%; 66 of 142) for very high likelihood, "most likely" (31.0%; 44 of 142) for high likelihood, "may represent" (50.7%; 72 of 142) for intermediate likelihood, "unlikely" (47.2%; 67 of 142) for low likelihood, and "very unlikely" (40.1%; 57 of 142) for very low likelihood. Cluster analysis identified six groups of phrases used to indicate a similar level of diagnostic certainty; however, Krippendorff's α was 0.217, indicating radiologists do not consistently use the same phrases for similar degrees of confidence. Conclusion: Wide variability persists among radiologists' preferences for phrases used to convey diagnostic certainty. Interventions to improve consistency of use of these phrases may help reduce ambiguity and improve quality of radiology reports.

Chronic Mesenteric Ischemia: Clinical Diagnosis, Imaging Characteristics, and Endovascular Management

Article

Aug 2018

Chronic mesenteric ischemia (CMI) is a complex disorder, which typically affects elderly patients who classically present with longstanding abdominal pain and nonspecific clinical symptoms, such as food aversion and weight loss. The disease progression is often gradual due to a rich collateral network, and symptoms are generally not clinically apparent until two or more primary visceral arteries are affected. Symptomatic stenosis or occlusion of the mesenteric arteries can be the result of multiple etiologies, although atherosclerosis is the most common. Given its low incidence, a high clinical suspicion is necessary for diagnosis and to prevent a delay in treatment. Multiple imaging modalities are utilized to confirm the presence of mesenteric vessel involvement and to guide treatment. While open surgical revascularization was once the definitive treatment, endovascular management has become the first-line treatment for atherosclerotic CMI. The endovascular approach with stent placement has shown excellent primary success and encouraging long-term outcomes with reduction in morbidity and mortality compared with open surgical revascularization. Although controversial, median arcuate ligament syndrome (MALS) is a less common cause of CMI, which can affect a more varied patient population. Clinical approach, imaging characteristics, and treatment for this syndrome will also be discussed.

Surgical Intervention for Chronic Mesenteric Ischemia

Article

Aug 2018

Symptomatic chronic mesenteric ischemia (CMI) is a relatively rare condition, yet there are significant clinical consequences for those affected by the disease. CMI not only reduces quality of life but also increases an individual's risk for life-threatening acute mesenteric ischemia. Surgery is the definitive treatment to reduce the risk for this potentially fatal outcome, and both endovascular and open surgical strategies are currently utilized. This review article discusses the approach to making a diagnosis of CMI, as well as the surgical techniques used to revascularize the mesenteric circulation.

Lower extremity CT angiography in peripheral arterial disease: from the established approach to evolving technical developments

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