Wan-Chun Liao

Vertebral and carotid artery anomalies in patients with aberrant right subclavian arteries

BackgroundThere is little published evidence regarding the patterns and prevalence of vertebral artery (VA) and common carotid artery (CCA) anomalies in patients with an aberrant right subclavian artery (ARSCA).ObjectiveTo study the patterns and prevalence of VA and CCA anomalies in patients with ARSCA.Materials and methodsIn a 2-year period we reviewed the children referred with suspected vascular ring who had undergone multidetector-row CT. Patients with ARSCA were reviewed for VA and CCA patterns and their prevalence and relevance were calculated.ResultsIn total, 102 patients with ARSCA were identified. VA anomalies were present in 16 patients (15.7%), and CCA anomalies (common carotid trunk) in 21 patients (20.6%). In some patients with VA anomalies, the right VA arose from the right CCA and in some the left VA arose from the aortic arch. When the left VA arose from the aortic arch it was situated between the left CCA and the left SCA or between the left SCA and the ARSCA.ConclusionIf neurointerventionalists understand these potential anomalies and their prevalence, time and contrast medium could be saved when catheterizing the VA and CCA in patients with ARSCA.

Comprehensive evaluation of ischemic heart disease using MDCT.

OBJECTIVE Recently MDCT has become widely used for the evaluation of ischemic heart disease, but clinically the evaluation is primarily focused on the coronary artery only. We describe why and how to comprehensively evaluate the cardiac CT scan, including myocardium, motion, viability, valve, and perfusion aspects related to ischemic heart disease. CONCLUSION Radiologists should be familiar with the protocol design and comprehensive interpretation of cardiac MDCT to provide comprehensive treatment suggestions for the patients.

Homogeneous enhancement in pediatric thoracic CT aortography using a novel and reproducible method: contrast-covering time.

OBJECTIVE This study compares the empiric setting and contrast-covering time (CCT) concept for i.v. contrast injection in pediatric thoracic CT aortography. SUBJECTS AND METHODS A total of 113 pediatric patients referred for thoracic CT aortography were classified into four groups: group 1 (1-5 years old, CCT), group 2A (6-10 years old, CCT), group 2B (6-10 years old, empiric setting), and group 3 (11-15 years old, CCT). The CT attenuation values from the left common carotid artery to the descending aorta were recorded every 0.5 second. The quantitative bolus geometric analysis of each group included average enhancement, SD within the patient, and slope of enhancement. Groups 2A and 2B were compared to determine whether better bolus geometry could be obtained with the CCT concept than with the traditional empiric setting. Groups 1, 2A, and 3 were compared to determine whether homogeneous bolus geometry could be obtained in different age groups. RESULTS More homogeneous enhancement was obtained with the CCT concept than the empiric setting with a smaller SD of enhancement (25.5 +/- 8.5 H vs 49.3 +/- 16.2 H, p < 0.001). Furthermore, in the three different age groups (groups 1, 2A, and 3) examined using the CCT concept, there was no significant difference in the average enhancement (415.7 +/- 83.6 H, 422.8 +/- 97.1 H, 392.0 +/- 78.5 H, respectively; all p > 0.05), SD of enhancement (28.5 +/- 9.8 H, 25.5 +/- 8.5 H, 28.5 +/- 14.6 H, respectively; all p > 0.05), or enhancement slopes (-5.6 +/- 18.0 H, -2.7 +/- 10.7 H, -5.4 +/- 12.3 H, respectively; all p > 0.05). CONCLUSION The CCT concept yields more homogeneous enhancement than the empiric setting. It also can routinely obtain homogeneous bolus geometry in patients in different age groups.

Comprehensive MDCT Evaluation of Patients With Pulmonary Hypertension: Diagnosing Underlying Causes With the Updated Dana Point 2008 Classification

OBJECTIVE Pulmonary hypertension is a challenge for imagers and clinicians, with a variety of possible underlying causes, each with its own specific treatment. Although the diagnosis is based on physiologic measurements, ECG-gated MDCT can play a vital role in elucidating underlying cardiac, vascular, and pulmonary causes. CONCLUSION A revised system for pulmonary hypertension, the Dana Point classification, can provide a template for review of the myriad causes of this complex condition.

Arteriovenous Fistula and Graft Evaluation in Hemodialysis Patients Using MDCT: A Primer

OBJECTIVE Patent arteriovenous fistula (AVF) is related to better prognosis and quality of life for patients on long-term dialysis. When AVF dysfunction is suspected, MDCT is a good noninvasive tool for evaluating the entire AVF structure and determining reversible conditions for treatment. The aim of this article is to introduce the scanning and interpretation techniques and to illustrate the conditions related to early and late fistula failures. CONCLUSION MDCT is a fast, noninvasive, and accurate technique for diagnosing AVF complications. Radiologists familiar with these techniques can help to improve the prognosis and quality of life for hemodialysis patients.

Left ventricular myocardial volumes measured during arterial and delayed phases of multidetector row computed tomography: a study on intra- and interobserver variability.

To compare and correlate left ventricular (LV) myocardial volumes obtained using arterial and delayed phases of multidetector row computed tomography (CT) and evaluate their intra- and interobserver variation. Two observers evaluated the arterial- and delayed-phase serial short-axis images of 45 healthy volunteers. Intra- and interobserver variations in LV myocardial volumes were correlated with four factors—myocardial volume, contrast-volume-to-body-weight ratio, and contrast-to-noise ratios in the arterial and delayed phases. Variations in the apex, mid-ventricle, and base were compared. Intra- and interobserver analyzes revealed no statistical difference and good correlation. Intra- and interobserver variations were within 5 and 10%, respectively, and were independent of the four factors. Variations were the highest at the apex. LV myocardial volumes measured using arterial- and delayed-phase cardiac CT exhibit no significant difference and good correlation. Intra- and interobserver variations are both clinically acceptable, and the apex contributes most to these variations.

Comprehensive evaluation of patients with suspected renal hypertension using MDCT: from protocol to interpretation.

OBJECTIVE The objectives of this article are to, first, describe the reasons for and details of the MDCT protocol for patients with suspected renal hypertension; second, explain the importance of comprehensive evaluation by MDCT in patients with suspected renal hypertension; third, review the image appearances of important conditions that may be encountered in the readers clinical practice; and, fourth, explain what information should be included in a comprehensive MDCT report for patients with suspected renal hypertension. CONCLUSION MDCT is widely used for renal artery evaluation in patients with resistant hypertension. Because the regions outside the renal arteries might also have diseases that contribute to the symptoms, a comprehensive interpretation including the renal arteries, renal parenchyma, adrenal glands, and scanned abdomen is very important. The scanning parameters should be adjusted according to the patients body habitus because some patients with suspected renal hypertension are children or young women. In this article, cases with illustrations showing the process from protocol to interpretation are provided.

Comprehensive Evaluation of Patients With Suspected Prosthetic Heart Valve Disorders Using MDCT

OBJECTIVE Early diagnosis of prosthetic valve disorders is very important in reducing morbidity and mortality of patients with a replaced heart valve. Recently, MDCT has become an important noninvasive problem-solving tool in clinical practice. This article will introduce the scanning technique, interpretation algorithm, and image findings of many valvular and extravalvular diagnoses. CONCLUSION With proper scanning technique and interpretation, MDCT can be a powerful technique for prosthetic heart valve evaluation.