Elsie T. Nguyen

ALCAPA Syndrome: Not Just a Pediatric Disease

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) syndrome is a rare congenital coronary artery anomaly. There are two types of ALCAPA syndrome: the infant type and the adult type, each of which has different manifestations and outcomes. Infants experience myocardial infarction and congestive heart failure, and approximately 90% die within the 1st year of life. Rarely, ALCAPA syndrome manifests in adults; it may be an important cause of sudden cardiac death. Historically, ALCAPA syndrome was diagnosed at conventional angiography. However, the development of electrogardiographically gated multidetector computed tomographic (CT) angiography and magnetic resonance (MR) imaging enables accurate noninvasive imaging. At MR imaging and multidetector CT angiography, findings include direct visualization of the left coronary artery arising from the main pulmonary artery. Reversed flow from the left coronary artery into the main pulmonary artery may be seen at steady-state free-precession cine and fast cine phase-contrast MR imaging. Because of its ability to assess myocardial viability, which can be used as a prognostic factor to direct the need for surgical repair, MR imaging plays an important role in patient treatment. Restoration of a dual-coronary-artery system is the ideal surgical treatment for ALCAPA syndrome.

Pulmonary artery aneurysms and pseudoaneurysms in adults: findings at CT and radiography.

OBJECTIVE The purpose of this pictorial essay is to illustrate the radiologic manifestations of pulmonary artery aneurysms and pseudoaneurysms with emphasis on the findings on contrast-enhanced CT. CONCLUSION Pulmonary artery aneurysms and pseudoaneurysms are uncommon. Most are caused by trauma, often iatrogenic, infection, and Behçets syndrome. Less common causes include pulmonary hypertension, congenital heart disease, neoplasms, and connective tissue disease. Recognition of pulmonary artery aneurysms and pseudoaneurysms is important because of the high morbidity and mortality rates of rupture.

Cardiac Magnetic Resonance Imaging and the Assessment of Ebstein Anomaly in Adults

No published studies have evaluated the role of cardiac magnetic resonance (CMR) imaging for the assessment of Ebstein anomaly. Our objective was to evaluate the right heart characteristics in adults with unrepaired Ebstein anomaly using contemporary CMR imaging techniques. Consecutive patients with unrepaired Ebstein anomaly and complete CMR studies from 2004 to 2009 were identified (n = 32). Volumetric measurements were obtained from the short-axis and axial views, including assessment of the functional right ventricular (RV) end-diastolic volume (EDV) and end-systolic volume. The volume of the atrialized portion of the right ventricle in end-diastole was calculated as the difference between the total RVEDV and the functional RVEDV. The reproducibility of the measurements in the axial and short-axis views was determined within and between observers. The median value derived from the short-axis and axial views was 136 ml/m(2) (range 59 to 347) and 136 ml/m(2) (range 63 to 342) for the functional RVEDV, 153 ml/m(2) (range 64 to 441) and 154 ml/m(2) (range 67 to 436) for the total RVEDV, 49% (range 32% to 46%) and 50% (range 40% to 64%) for the functional RV ejection fraction, respectively. The axial measurements demonstrated lower intraobserver and interobserver variability than the short-axis approach for all values, with the exception of the intraobserver functional RVEDV and interobserver total RVEDV for which the limits of agreement and variance were not significantly different between the 2 views. In conclusion, measurements of right heart size and systolic function in patients with Ebstein anomaly can be reliably achieved using CMR imaging. Axial imaging appeared to provide more reproducible data than that obtained from the short-axis views.

CT and MR imaging findings in patients with acquired heart disease at risk for sudden cardiac death.

Noninvasive imaging is an important screening and diagnostic tool in conditions associated with sudden cardiac death. The most common cause of sudden cardiac death is coronary artery disease, with myocarditis, cardiac sarcoidosis, and dilated and infiltrative cardiomyopathies being less common acquired causes. Common risk factors for sudden cardiac death, regardless of the disease process, include severe ventricular dysfunction and the presence of macroscopic scar seen at delayed contrast material-enhanced imaging. Recent advances in electrocardiographically (ECG) gated cardiac magnetic resonance (MR) imaging and multidetector computed tomography (CT) have led to increased referrals for cross-sectional imaging; thus, cardiac radiologists should be familiar with the disease entities associated with sudden cardiac death. Inflammatory processes and cardiomyopathies are best depicted with cardiac MR imaging. Steady-state free precession cine sequences coupled with inversion-recovery prepared gradient-echo T1-weighted sequences performed after the intravenous administration of gadolinium-based contrast material should form the basis of cardiac MR imaging protocols for cardiomyopathy. A clinical history that is suggestive of myocardial ischemia, specific requests to exclude coronary artery disease, or contraindications for MR imaging may imply that multidetector CT would be more appropriate. Nevertheless, both cardiac MR imaging and ECG-gated multidetector CT offer robust diagnosis and risk stratification for individual disease processes associated with sudden cardiac death.

Malignant pleural mesothelioma: computed tomography and correlation with histology.

OBJECTIVE To review the computed tomography (CT) imaging findings of pleural mesothelioma at presentation and to correlate the CT with the histological subtype. MATERIALS AND METHODS Pathology reports from 1997 to 2006 were reviewed at two academic institutions to identify patients with proven pleural mesothelioma. Diagnosis was based on histologic findings in specimens obtained by transthoracic needle biopsy, surgical biopsy or resection. All histology slides were reviewed by a lung pathologist. CT scans, available in 92 patients, were reviewed blindly and in random order by two independent radiologists. Kappa analysis was completed to assess inter-observer agreement. Eighty patients in whom there was no significant delay between CT imaging and histological diagnosis were assessed by logistic regression analysis to correlate CT and histologic findings. RESULTS Seventy-two of the 92 mesotheliomas were epithelial, 15 sarcomatous, and 5 of mixed histology. All patients (77 male, 15 female, mean age 68 years) had pleural thickening on CT; the thickening was nodular in 79 patients (86%) and mediastinal in 87 (95%). Ipsilateral volume loss was seen in 42 patients (46%). Pleural effusions were present in 80 patients (87%), being large (>2/3 hemithorax) in 19 patients (21%). Atypical features at presentation included bilateral disease in three patients (3%), and spontaneous pneumothoraces in nine patients (10%). Internal mammary lymphadenopathy was observed in 48 patients (52%) and cardiophrenic lymphadenopathy in 42 (46%). Inter-observer agreement was excellent (average kappa=0.89). Ipsilateral volume loss was associated with sarcomatous or mixed mesothelioma (p=0.004). Using logistic regression analysis, other CT findings did not correlate with histological subtype. CONCLUSIONS Ipsilateral volume loss is most frequently associated with sarcomatous or mixed mesothelioma. The remaining imaging findings are not helpful in predicting the histological subtype of malignant mesothelioma.

Extracellular volume fractions in chronic myocardial infarction.

ObjectivesThe aim of this study was to assess and delineate chronic myocardial infarction (CMI) using precontrast and postcontrast T1 mapping techniques including quantification of extracellular volume fractions (ECVs). Materials and MethodsA total of 26 patients with CMI were examined at 1.5 T applying a modified Look-Locker Inversion Recovery sequence before and 10 minutes after contrast at 3 short-axis slice positions. An inversion recovery gradient recalled echo sequence (standard of reference) was used for imaging late gadolinium enhancement. Precontrast and postcontrast T1 maps were calculated, and CMI was defined as areas with T1 values more than 3 SDs different compared with normal myocardium (MYO). T1 values of CMI, MYO, and blood pool were measured, and ECVs of CMI and MYO were calculated. Two-tailed Student t test was used for statistical analysis of T1 values and ECVs. Sensitivities and specificities for detection of CMI on precontrast and postcontrast T1 maps were calculated. Receiver operating characteristic (ROC) analysis was performed for postcontrast T1 values and ECV for discrimination of CMI. ResultsThe comparison of T1 values of CMI and MYO revealed significant differences in precontrast and postcontrast scans (1159 ± 64 vs 1001 ± 47 milliseconds, P < 0.001, and 238 ± 74 vs 379 ± 59 milliseconds, P < 0.001). Sensitivities and specificities for detection of CMI on T1 mapping were 41.7% and 100% in precontrast Look-Locker Inversion Recovery scans and 95.8% and 99.3% in postcontrast images, respectively. Average ECV for MYO and CMI were 28% ± 5% and 53% ± 10% (P < 0.001). ROC analysis revealed nonsignificantly different areas under the curve of 0.937 and 0.997 for T1 values and ECV, respectively (P = 0.137). Sensitivities and specificities were 92.3% and 92.3% for detecting CMI by postcontrast T1 values and 95.5% and 100% for ECV, with cutoff values being 305 milliseconds or less and greater than 42%. Combined criteria did not result in any further improvement of sensitivity for CMI detection. ConclusionsPostcontrast T1 values and ECV of chronically infarcted MYO are significantly different compared with respective values of normal MYO. Both parameters allow for accurate detection of CMI with ECV showing marginally higher sensitivity and specificity. Precontrast T1 values lack accuracy in delineation of CMI.

Community-acquired methicillin-resistant Staphylococcus aureus pneumonia: radiographic and computed tomography findings.

Objective The aim of our study was to review the radiologic findings of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) pneumonia. Materials and Methods The hospital infection control computer database was used to identify patients who had a CA-MRSA infection with organisms isolated from blood, bronchoalveolar lavage fluid, or pleural fluid samples. Criteria for CA-MRSA pneumonia were consolidation seen on chest radiography or computed tomography (CT), growth of MRSA from sputum and/or sterile pulmonary site, clinical complaints of cough and/or shortness of breath. Chest radiographs and CT scans for 9 patients (5 men, mean age 45 y, range 35 to 71 y) were retrospectively reviewed by 2 chest radiologists. Results The most common chest radiographic finding was consolidation, which was bilateral in 7 patients and unilateral in 2 patients. The consolidation was patchy and nonsegmental in 5 and segmental in 4 patients. Two patients had cavitation evident on the chest radiograph. The most common CT scan findings were bilateral (n=8), often symmetric (n=5) consolidation, bilateral septal lines (n=7), and multiple nodules (n=5). Cavitation was present in 5 patients, either in regions of consolidation (n=5) or in large nodules (n=3). Five patients with CA-MRSA pneumonia had rapid clinical deterioration requiring ventilatory support. Two patients died. Conclusions CA-MRSA pneumonia is characterized by extensive bilateral consolidation and frequent cavitation and is commonly associated with rapid progression and clinical deterioration. CT is superior to radiography in demonstrating the presence of cavitation.

Cardiac magnetic resonance imaging findings predict major adverse events in apical hypertrophic cardiomyopathy.

Purpose: The purpose of this study was to determine the prognostic significance of cardiac magnetic resonance imaging (MRI) findings in patients with apical hypertrophic cardiomyopathy (HCM). Materials and Methods: Cardiac MRI studies of 93 consecutive patients with apical HCM were retrospectively evaluated. Quantification of late gadolinium enhancement (LGE) was determined and expressed as a percentage of total left ventricular (LV) myocardial mass (%LGE). Morphologic features including presence of apical aneurysm, right ventricular hypertrophy, and LV thrombus were also assessed. Clinical data were collected during follow-up to assess for occurrence of major adverse events, defined as: heart failure, stroke, appropriate automatic implantable cardioverter defibrillator discharge, sustained ventricular tachycardia, aborted sudden cardiac death, and/or all-cause death. Results: The mean age of the patients was 54.9±13.8 years, and 72.0% (n=67) were male. LGE, right ventricular hypertrophy, apical aneurysm, and LV thrombus were identified in 69.4%, 25.8%, 18.3%, and 4.3%, respectively. Mean %LGE was 10.8%±11.1%. Over 2.4±1.7 years of follow-up, 14 subjects (15.1%) experienced a major adverse event (event rate, 6.3%/y): heart failure (6.5%), stroke (6.5%), appropriate automatic implantable cardioverter defibrillator discharge (2.2%), sustained ventricular tachycardia (2.2%), aborted sudden cardiac death (1.1%), and all-cause death (0.0%). Presence of apical aneurysm and extent of LGE were significant predictors of major adverse events [odds ratio (OR) 4.6, P=0.015; and OR 1.4/5% LGE, P=0.030, respectively]. Patients with both apical aneurysm and >5% LGE were at highest risk for major adverse events (OR 6.7, P=0.004) and had shortest event-free survival (P=0.001). Conclusions: Within our population of apical HCM patients, the extent of LGE and the presence of an apical aneurysm identified by cardiac MRI were both significant predictors of major adverse clinical events.

Accuracy of Right and Left Ventricular Functional Assessment by Short-Axis vs Axial Cine Steady-State Free-Precession Magnetic Resonance Imaging: Intrapatient Correlation With Main Pulmonary Artery and Ascending Aorta Phase-Contrast Flow Measurements

Objective The left ventricle (LV) is routinely assessed with cardiac magnetic resonance imaging (MRI) by using short-axis orientation; it remains unclear whether the right ventricle (RV) can also be adequately assessed in this orientation or whether dedicated axial orientation is required. We used phase-contrast (PC) flow measurements in the main pulmonary artery (MPA) and the ascending aorta (Aorta) as nonvolumetric standard of reference and compared RV and LV volumes in short-axis and axial orientations. Methods A retrospective analysis identified 30 patients with cardiac MRI data sets. Patients underwent MRI (1.5 T or 3 T), with retrospectively gated cine steady-state free-precession in axial and short-axis orientations. PC flow analyses of MPA and Aorta were used as the reference measure of RV and LV output. Results There was a high linear correlation between MPA-PC flow and RV–stroke volume (SV) short axis (r = 0.9) and RV-SV axial (r = 0.9). Bland-Altman analysis revealed a mean offset of 1.4 mL for RV axial and −2.3 mL for RV–short-axis vs MPA-PC flow. There was a high linear correlation between Aorta-PC flow and LV-SV short-axis (r = 0.9) and LV-SV axial (r = 0.9). Bland-Altman analysis revealed a mean offset of 4.8 m for LV short axis and 7.0 mL for LV axial vs Aorta-PC flow. There was no significant difference (P = .6) between short-axis–LV SV and short-axis–RV SV. Conclusion No significant impact of the slice acquisition orientation for determination of RV and LV stroke volumes was found. Therefore, cardiac magnetic resonance workflow does not need to be extended by an axial data set for patients without complex cardiac disease for assessment of biventricular function and volumes.

Quantification of Myocardial Extracellular Volume Fraction with Cardiac MR Imaging in Thalassemia Major

Purpose To quantify myocardial extracellular volume (ECV) by using cardiac magnetic resonance (MR) imaging in thalassemia major and to investigate the relationship between ECV and myocardial iron overload. Materials and Methods With institutional review board approval and informed consent, 30 patients with thalassemia major (mean age ± standard deviation, 34.6 years ± 9.5) and 10 healthy control subjects (mean age, 31.5 years ± 4.4) were prospectively recruited (clinicaltrials.gov identification number NCT02090699). Nineteen patients (63.3%) had prior myocardial iron overload (defined as midseptal T2* < 20 msec on any prior cardiac MR images). Cardiac MR imaging at 1.5 T included cine steady-state free precession for ventricular function, T2* for myocardial iron quantification, and unenhanced and contrast material-enhanced T1 mapping. ECV was calculated with input of the patients hematocrit level. Peak systolic global longitudinal strain by means of speckle tracking was assessed with same-day transthoracic echocardiography. Statistical analysis included use of the two-sample t test, Fisher exact test, and Spearman correlation. Results Unenhanced T1 values were significantly lower in patients with prior myocardial iron overload than in control subjects (850.3 ± 115.1 vs 1006.3 ± 35.4, P < .001) and correlated strongly with T2* values (r = 0.874, P < .001). Patients with prior myocardial iron overload had higher ECV than did patients without iron overload (31.3% ± 2.8 vs 28.2% ± 3.4, P = .030) and healthy control subjects (27.0% ± 3.1, P = .003). There was no difference in ECV between patients without iron overload and control subjects (P = .647). ECV correlated with lowest historical T2* (r = -0.469, P = .010) but did not correlate significantly with left ventricular ejection fraction (r = -0.216, P = .252) or global longitudinal strain (r = -0.164, P = .423). Conclusion ECV is significantly increased in thalassemia major and is associated with myocardial iron overload. These abnormalities may potentially reflect diffuse interstitial myocardial fibrosis. (©) RSNA, 2015 Online supplemental material is available for this article.