Coronary Computed Tomography Angiography Demonstrates a High Burden of Coronary Artery Disease Despite Low-Risk Nuclear Studies in Pre-Liver Transplant Evaluation.

We investigated the presence and severity of coronary artery disease (CAD) in orthotopic liver transplantation (OLT) candidates using coronary artery calcium score (CACS) and coronary computed tomography angiography (CCTA) as compared with the prevalence of normal and abnormal single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). A total of 140 prospective OLT candidates without known CAD underwent coronary artery calcium (CAC) scans with (n = 77) or without CCTA and coronary computed tomography angiography-derived fractional flow reserve (FFRCT ; n = 57) using a dual-source computed tomography (CT) and were followed for 2.6 ± 1.4 years. Coronary plaque was quantified using the segment-involvement score (SIS) and segment stenosis score (SSS). The mean age was 59 ± 6 years, and 65.0% of patients were male. Mean Agatston CACS was 367 ± 653, and 15.0% of patients had CACSs of 0; 83.6% received a SPECT MPI, of which 95.7% were interpreted as normal/probably normal. By CCTA, 9.1% had obstructive CAD (≥70% stenosis), 67.5% had nonobstructive CAD, and 23.4% had no CAD. Nonobstructive CAD was diffuse with mean SIS 3.0 ± 2.9 and SSS 4.5 ± 5.4. Only 14 patients had high risk-findings (severe 3v CAD, n = 4, CACS >1000 n = 10) that prompted X-ray angiography in 3 patients who had undergone CCTA, resulting in revascularization of a high-risk obstruction in 1 patient who had a normal SPECT study. Patients with end-stage liver disease have a high prevalence of nonobstructive CAD by CCTA, which is undiagnosed by SPECT MPI, potentially underestimating cardiovascular risk. Deferring X-ray angiography unless high-risk CCTA findings are present is a potential strategy for avoiding unnecessary X-ray angiography.

Effect of ablation pattern on mechanical function in the atrium.

BACKGROUND: Atrial fibrillation (AF) is often treated with catheter ablation, which induces scar formation to isolate misfiring electrical signals in the left atrium. Successful ablation restores sinus rhythm at the cost of replacing viable myocardium with scar. The impact of ablation scar on mechanical function of the left atrium is poorly understood. OBJECTIVE: We used a computational model to simulate various ablation patterns and determine their effect on atrial global and regional mechanical function. METHODS: A coupled finite-element and hemodynamic circuit model of the left atrium that represents the regional and global mechanics in paroxysmal AF patients was modified to simulate different ablation patterns: step-wise pulmonary vein isolation (PVI), wide area circumferential ablation (WACA), and a posterior ablation developed by nContact, Inc (Morrisville, NC, USA). Atrial pressure-volume relationships and regional wall motion were compared among the models. RESULTS: Ablation increased passive stiffness and decreased active work performed by the atrium. Active emptying volume decreased with increasing scar by up to 44% (11 mL) at a scar volume of 31%. At matched scar volumes, WACA decreased active emptying more severely than PVI and nContact. Similarly, wall motion was depressed most in the WACA model because WACA involved portions of the lateral wall with higher baseline motion. CONCLUSION: Simulated ablation depressed atrial mechanical function to an extent that depended on both scar volume and location, primarily through reducing active emptying. Placing ablation scar in regions with high baseline motion resulted in greater depression of active function, while ablation of the posterior wall was less disruptive.

Development of bilateral coronary artery aneurysms in a child with Noonan syndrome.

Noonan syndrome is a constellation of congenital malformations including heart defects, facial anomalies and short stature. The cardiovascular defects are variable and extensive, with the most common being pulmonary stenosis and hypertrophic cardiomyopathy. Coronary artery anomalies have only been reported in a few cases. We report a child with Noonan syndrome status post pulmonary stenosis and atrial septal defect repair, who developed bilateral coronary artery aneurysms. The aneurysms were diagnosed with both cardiac magnetic resonance imaging and coronary computed tomography angiography. There had been no evidence of them on a cardiac MR exam 5 years previously.

Noncontrast peripheral MRA with spiral echo train imaging.

PURPOSE: To develop a spin echo train sequence with spiral readout gradients with improved artery-vein contrast for noncontrast angiography. THEORY: Venous T2 becomes shorter as the echo spacing is increased in echo train sequences, improving contrast. Spiral acquisitions, due to their data collection efficiency, facilitate long echo spacings without increasing scan times. METHODS: Bloch equation simulations were performed to determine optimal sequence parameters, and the sequence was applied in five volunteers. In two volunteers, the sequence was performed with a range of echo times and echo spacings to compare with the theoretical contrast behavior. A Cartesian version of the sequence was used to compare contrast appearance with the spiral sequence. Additionally, spiral parallel imaging was optionally used to improve image resolution. RESULTS: In vivo, artery-vein contrast properties followed the general shape predicted by simulations, and good results were obtained in all stations. Compared with a Cartesian implementation, the spiral sequence had superior artery-vein contrast, better spatial resolution (1.2 mm(2) versus 1.5 mm(2) ), and was acquired in less time (1.4 min versus 7.5 min). CONCLUSION: The spiral spin echo train sequence can be used for flow-independent angiography to generate three-dimensional angiograms of the periphery quickly and without the use of contrast agents.

Glomuvenous malformation: magnetic resonance imaging findings.

We report a case of a glomuvenous malformation involving the dorsal aspect of the right hand and distal forearm in an 11-year-old boy. He had a history of multiple vascular anomalies since birth and presented with increasing right hand pain. MRI played an important role in characterizing and determining the extent of the lesion. In particular, dynamic time-resolved contrast-enhanced MR angiography precisely defined its vascularity. The diagnosis was made histopathologically after partial resection of the lesion. Glomuvenous malformation is a rare developmental hamartoma that originates from the glomus body. Clinically they usually resemble a venous malformation but they are a different entity. In the appropriate clinical setting this rare condition must be included in the differential diagnosis of a vascular malformation, especially when subtle arterial enhancement, early venous shunting and progressive filling of dilated venous spaces are depicted on MRA.

Refocused turbo spin-echo for noncontrast peripheral MR angiography.

PURPOSE: To develop and assess a three-dimensional refocused turbo spin-echo (rTSE) sequence for generating peripheral angiograms. This sequence combines the rapid T2 -weighting of TSE and the better flow performance of the fully-refocused gradients of balanced steady state free precession (bSSFP), along with bSSFP-style phase alternation of refocusing radiofrequency (RF) pulses. MATERIALS AND METHODS: The signal behavior generated by such a sequence was explored through Bloch equation simulations. The rTSE and TSE sequences were both used to generate peripheral angiograms in nine normal volunteers. The signal to noise ratio, contrast resolution, and vessel sharpness of the resulting images were used as bases for comparison. Additionally, the rTSE sequence was applied in four patients with peripheral artery disease to preliminarily assess its efficacy in a clinical setting through quality scoring by two experienced radiologists. RESULTS: The rTSE's RF phase alternation approach out-performs a simple balanced-gradient CPMG (Carr-Purcell-Meiboom-Gill) -style TSE sequence in the presence of B0 and B1 inhomogeneities. In volunteers, the rTSE sequence yielded better arterial-venous contrast (0.378 ± 0.145 versus 0.155 ± 0.202; P < 0.01) and increased vessel sharpness (0.340 ± 0.034 versus 0.263 ± 0.034; P < 0.005) over TSE images. Stenoses visible in conventional angiographic images in patients were successfully imaged with the rTSE sequence; however, image quality scores in patients were lower than in volunteers (1.2 ± 0.38 versus 3.0 ± 1.0; P < 0.05). CONCLUSION: The rTSE sequence generates nonsubtractive, flow-independent, peripheral MR angiograms with better arterial-venous contrast and vessel sharpness in normal volunteers than a conventional TSE sequence.

Imaging follow-up of endovascular repair of type B aortic dissection with dual-source, dual-energy CT and late delayed-phase scans.

PURPOSE: To evaluate the diagnostic performance of dual-energy (DE) computed tomography (CT) after thoracic endovascular aortic repair (TEVAR) of type B dissection, and to investigate the value of late delayed (LD) acquisition in endoleak detection and false lumen patency assessment. MATERIALS AND METHODS: Twenty-four patients with TEVAR for type B dissection underwent 53 tripe-phase CT examinations. Single-source unenhanced acquisition was followed by single-source arterial-phase and DE LD phase (300-s delay) imaging. Virtual noncontrast images were generated from DE acquisition. Two blinded radiologists retrospectively evaluated the cases in three reading sessions: session A (triphasic protocol), session B (virtual noncontrast and arterial phase), and session C (virtual noncontrast and arterial and LD phases). Endoleak detection accuracy during sessions B and C compared with session A (reference standard) was investigated. False lumen patency was assessed. Effective radiation dose was calculated. RESULTS: Session A revealed 37 endoleaks in 30 of 53 studies (56.6%). Session B revealed 31 of the 37 endoleaks, with one false-positive case, 83.8% sensitivity, 95.8% specificity, 79.3% negative predictive value, and 96.9% positive predictive value. Session C correctly depicted all 37 endoleaks, with one false-positive case, 100% sensitivity, 95.8% specificity, 100% negative predictive value, and 97.4% positive predictive value. Underestimation of false lumen patency was found in session B (P = .013). Virtual noncontrast imaging resulted in 17% radiation exposure reduction. CONCLUSIONS: Virtual noncontrast imaging can replace standard unenhanced images in follow-up after TEVAR of type B dissection, thus reducing radiation dose. Delayed-phase imaging is valuable in low-flow endoleaks detection and false lumen patency assessment.

Endoleak detection after endovascular repair of thoracic aortic aneurysm using dual-source dual-energy CT: suitable scanning protocols and potential radiation dose reduction.

OBJECTIVE: The objective of our study was to evaluate the diagnostic performance of dual-source dual-energy CT (DECT) in the detection of endoleaks after thoracic endovascular aortic repair for thoracic aortic aneurysm and to investigate if a double-phase (arterial and dual-energy late delayed phase) or a single-phase (dual-energy late delayed phase) acquisition can replace the standard triphasic protocol. MATERIALS AND METHODS: All DECT examinations performed for evaluation after thoracic endovascular aortic repair during a 30-month period were retrospectively reviewed. An initial single-source unenhanced acquisition was followed by a single-source arterial phase acquisition and a dual-energy 300-second late delayed phase acquisition. "Virtual noncontrast images" were generated from the dual-energy acquisition. Two independent and blinded radiologists evaluated the cases during three reading sessions: session A (triphasic protocol: standard unenhanced, arterial phase, and late delayed phase), session B (virtual noncontrast and late delayed phase), and session C (virtual noncontrast, arterial phase, and late delayed phase). The diagnostic accuracies of sessions B and C were calculated using session A as the reference standard. Contrast-to-noise ratios and effective radiation doses were calculated. RESULTS: Forty-eight patients (mean age, 66 years; age range, 19-84 years) underwent 74 triple-phase CT examinations. The single-phase studies (session B) were characterized by 85.7% sensitivity, 100% specificity, 100% negative predictive value (NPV), and 94.6% positive predictive value (PPV). The dual-phase study (session C) revealed 100% sensitivity, 100% specificity, 100% NPV, and 100% PPV. The use of the dual-phase protocol and single-phase protocol resulted in a radiation exposure reduction of 19.5% and 64.1%, respectively. CONCLUSION: Virtual noncontrast and late delayed phase images reconstructed from a single DECT acquisition can replace the standard triphasic protocol in follow-up examinations after thoracic endovascular aortic repair, thereby providing a significant dose reduction.

CT angiography of the upper extremity arterial system: Part 1-Anatomy, technique, and use in trauma patients.

OBJECTIVE: In this article, we focus on the arterial anatomy of the upper extremities, the technical aspects of upper extremity CT angiography (CTA), and CTA use in trauma patients. CONCLUSION: CTA using modern MDCT scanners has evolved into a highly accurate noninvasive diagnostic tool for the evaluation of patients with abnormalities of the upper extremity arterial system.

CT angiography of the upper extremity arterial system: Part 2- Clinical applications beyond trauma patients.

OBJECTIVE: CT angiography using modern MDCT scanners has evolved into a highly accurate noninvasive diagnostic tool for the evaluation of patients with pathologic abnormalities of the upper extremity arterial system. CONCLUSION: Here we focus on the use of this modality in patients with nontraumatic vascular pathologic abnormalities.

Ten frequently asked questions about MRI evaluation of soft-tissue vascular anomalies.

OBJECTIVE: The objective of this article was to address 10 frequently asked questions that radiologists face when planning, performing, and interpreting an MRI study in a patient with a soft-tissue vascular anomaly. CONCLUSION: MRI permits a comprehensive assessment of vascular anomalies. It is important for radiologists to be familiar with the classification and correct nomenclature of vascular anomalies as well as the MRI protocol and distinct imaging findings of the different vascular malformations and tumors.

Noninvasive vascular imaging in abdominal solid organ transplantation.

OBJECTIVE: In this article, we focus on the vascular complications related to liver, pancreas, and kidney transplantation. CONCLUSION: Long term allograft survival of solid organ transplantation depends on early intervention of complications. Noninvasive imaging with ultrasound, CT, and MRI allows accurate diagnosis of complications and aids in treatment planning.

Diagnosis and treatment planning of acute aortic emergencies using a handheld DICOM viewer.

Acute aortic syndromes and traumatic aortic injury are often diagnosed on CT angiography, possibly requiring emergent intervention. Advances in handheld computing have created the possibility of viewing full DICOM datasets from a remote location. We evaluated the ability to diagnose and characterize acute aortic pathologies on CT angiograms of the thorax using an iPhone-based DICOM viewer. This study was performed after Institutional Review Board approval. Fifteen CT angiograms of the thorax in suspected acute aortic syndromes were evaluated by three blinded radiologists on a handheld device using a DICOM viewer. Studies were evaluated for the ability to identify and classify aortic dissection, transection, or intramural hematoma, measure aortic dimensions, and identify mediastinal hematoma, arch variants, and pulmonary pathology. Studies were compared to blinded interpretations on a dedicated PACS workstation. The aortic pathology was correctly identified as aortic transection/pseudoaneurysm (n = 5), type A dissection (n = 2), and type A intramural hematoma (n = 1) by all reviewers, with no false-positive interpretations. This represents a sensitivity and specificity of 100 %. Mediastinal hematoma (n = 6), pneumothorax (five right, three left), and arch vessel involvement (n = 2) were identified in all cases. There was 88.5 % accuracy in identifying arch variants. Measurement of the size of the involved aortic segment was similar on handheld device and PACS workstation; however the adjacent normal aorta was 1.2 ± 1.0 mm larger on the handheld device (p = 0.03). Handheld DICOM viewers may be useful for emergent consultations and triage, and may expedite preprocedure planning to reduce the time interval between diagnostic scan and therapeutic intervention.

Imaging evaluation of flow limitations in the iliac arteries in endurance athletes: diagnosis and treatment follow-up.

OBJECTIVE: The purpose of this article is to review the role of imaging in the diagnosis, treatment, and follow-up of patients with sport-related flow limitations in the iliac arteries. CONCLUSION: Endurance athletes can develop flow restriction during exercise because of endofibrosis or kinking of the iliac arteries. Knowledge of this entity and the use of appropriate imaging techniques are crucial for diagnosis. Imaging plays an important role in the assessment of the underlying lesion and its location as well as in posttreatment follow-up.

MR imaging of soft-tissue vascular malformations: diagnosis, classification, and therapy follow-up.

Vascular malformations and tumors comprise a wide, heterogeneous spectrum of lesions that often represent a diagnostic and therapeutic challenge. Frequent use of an inaccurate nomenclature has led to considerable confusion. Since the treatment strategy depends on the type of vascular anomaly, correct diagnosis and classification are crucial. Magnetic resonance (MR) imaging is the most valuable modality for classification of vascular anomalies because it accurately demonstrates their extension and their anatomic relationship to adjacent structures. A comprehensive assessment of vascular anomalies requires functional analysis of the involved vessels. Dynamic time-resolved contrast material-enhanced MR angiography provides information about the hemodynamics of vascular anomalies and allows differentiation of high-flow and low-flow vascular malformations. Furthermore, MR imaging is useful in assessment of treatment success and establishment of a long-term management strategy. Radiologists should be familiar with the clinical and MR imaging features that aid in diagnosis of vascular anomalies and their proper classification. Furthermore, they should be familiar with MR imaging protocols optimized for evaluation of vascular anomalies and with their posttreatment appearances. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.315105213/-/DC1.

Use of ascending aortic access for imaging and wire rail access for endograft delivery in complex aortic arch anatomy.

In cases of complex aortic arch anatomy, it can be difficult to obtain wire access into the ascending aorta for deployment of a thoracic endograft (thoracic endovascular aortic repair [TEVAR]) using a transfemoral approach. This can result from tortuosity or patulous aneurysmal areas, making platform stability difficult. We report the case of a young adult man with a large proximal left subclavian aneurysm that made zone 0 TEVAR placement very difficult with transfemoral access alone. Direct ascending aortic access through the open chest allowed for a stable through-and-through platform for endograft delivery, highlighting the efficacy of this seldom-needed technique during debranching TEVAR procedures.

Fibromuscular dysplasia: A comprehensive review on evaluation and management and role for multidisciplinary comprehensive care and patient input model.

Fibromuscular dysplasia is a nonatherosclerotic, under-recognized disorder primarily seen in middle-aged women. It can lead to several complications, such as hypertension, headaches, dissections, aneurysms, myocardial infarctions, and cerebrovascular accidents, to name a few. This article provides a comprehensive review of current literature on epidemiology, etiology, diagnosis, treatment, and long-term surveillance and fibromuscular dysplasia management. In addition, it renders the role of education and prevention for patients living with this condition and family screening. Lastly, it emphasizes the importance of a comprehensive multidisciplinary care model and patient input, given the complexity of this disease and its systemic presence and protean manifestations.

Preprocedural Imaging Evaluation of Pulmonary Valve Replacement After Repair of Tetralogy of Fallot: What the Radiologist Needs to Know.

Tetrallogy of Fallot (TOF) is the most frequent form of cyanotic congenital heart disease. Despite advances in surgical and medical treatment, mortality remains high. Residual dysfunction of the pulmonary valve (PV) after correction of right ventricular outflow tract obstruction is an important cause of morbidity, leading to irreversible right ventricular dysfunction, arrhythmias, heart failure and occasionally, death. The strategies for PVR have evolved over the last decades, and the timing of the intervention remains the foundation of the decision-making process. Symptoms of heart failure are unreliable indicators for optimal timing of repair. Imaging plays an essential role in the assessment of PV integrity and dysfunction. The identification of the best timing for PVR requires a multimodality approach. Transthoracic echocardiography is the most commonly used imaging modality for the initial assessment and follow-up of TOF patients, although its utility has technical limitations, especially in adults. Cardiac computed tomography and magnetic resonance imaging are now routinely used for preoperative and postoperative evaluation of these patients, and provide highly valuable information about the anatomy and pathophysiology. Imaging evidence of disease progression is now part of the major guidelines to define the best timing for reintervention. The purpose of this article is to review the pathophysiology after TOF repair, identify the main imaging anatomic and physiologic features, describe the indications for PVR and recognize the role of imaging in the assessment of these patients to define the appropriate timing of PVR.

CT angiography of renal arteriovenous fistulae: a report of two cases.

Renal arteriovenous fistulas (AVFs) are rare abnormal communications between the arterial and venous circulations that can be congenital or acquired. We describe the multidetector computed tomography angiography (MDCTA) appearance of 2 cases of renal AVF, one with the cirsoid and one with the aneurysmal subtype, and the impact of these findings on therapeutic decision making and treatment follow-up.