Jonathan D. Dodd

Cardiac Tumors: Optimal Cardiac MR Sequences and Spectrum of Imaging Appearances

OBJECTIVE This article reviews the optimal cardiac MRI sequences for and the spectrum of imaging appearances of cardiac tumors. CONCLUSION Recent technologic advances in cardiac MRI have resulted in the rapid acquisition of images of the heart with high spatial and temporal resolution and excellent myocardial tissue characterization. Cardiac MRI provides optimal assessment of the location, functional characteristics, and soft-tissue features of cardiac tumors, allowing accurate differentiation of benign and malignant lesions.

Significance of Cardiac Computed Tomography Incidental Findings in Acute Chest Pain

BACKGROUND Coronary computed tomography angiography might improve the management of patients presenting to the emergency department with acute chest pain; however, noncoronary incidental findings are frequently detected. The prevalence and clinical significance of these findings have not been well described. METHODS Consecutive patients presenting to the emergency department with acute chest pain and inconclusive initial evaluation between May 2005 and May 2007 underwent 64-slice coronary computed tomography angiography before hospital admission with noncoronary incidental findings immediately reported. An expert panel adjudicated which incidental findings changed in-hospital patient management, and projections for additional testing were based on standard medical practice. RESULTS Among 395 patients (37.0% were female, mean age 53 +/- 12 years), incidental findings were detected in 44.8% (n = 177): noncalcified pulmonary nodules (n = 94, 23.8%), simple liver cysts (n = 26, 6.6%), calcified pulmonary nodules (n = 16, 4.1%), and contrast-enhancing liver lesions (n = 9, 2.3%). In-hospital management was changed because of incidental finding reporting in 5 patients (1.3%), and a potential alternative diagnosis was offered in another 16 patients (4.1%). Subsequent diagnostic imaging tests were recommended in 81 patients (20.5%), including 74 chest computed tomography scans. After 6 months, biopsy was performed in 3 patients, revealing cancer in 2 (0.5%) who underwent successful tumor resection. CONCLUSION Clinically important findings are detected in up to 5% of patients with a lead symptom of acute chest pain and low to intermediate likelihood of acute coronary syndrome, but only few directly change patient management; 21% are recommended for further imaging tests, resulting in invasive procedures and detection of cancer in few patients.

Quantification of Left Ventricular Noncompaction and Trabecular Delayed Hyperenhancement with Cardiac MRI: Correlation with Clinical Severity

OBJECTIVE The purpose of this study was to investigate whether MRI can quantify the severity and extent of left ventricular noncompaction and detect trabecular delayed hyperenhancement and whether doing so can show a relationship with clinical stage of disease. MATERIALS AND METHODS In a retrospective blinded study, nine patients with left ventricular noncompaction and 10 control subjects had cardiac MRI studies evaluated for the severity and extent of left ventricular noncompaction and the amount and degree of trabecular delayed hyperenhancement on a myocardial segment basis (16-segment model). Findings were correlated with parameters of clinical stage of disease. RESULTS Fifty-seven (39%) myocardial segments showed left ventricular noncompaction whereas 22 (17%) showed trabecular delayed hyperenhancement. Significant differences among clinical severity groups were noted in the severity and extent of left ventricular noncompaction at the mid (p < 0.05 and p < 0.005, respectively) and apical levels (p < 0.003 and p < 0.001, respectively), severity of trabecular delayed hyperenhancement at the mid (p < 0.04) and apical levels (p < 0.02), and amount of trabecular delayed hyperenhancement at the apical level (p < 0.006). The extent of left ventricular noncompaction and the amount and degree of trabecular delayed hyperenhancement correlated significantly with ejection fraction (EF) (r = -0.47, -0.53, -0.53, respectively, p < 0.05). The degree of trabecular delayed hyperenhancement was an independent predictor of EF (R2 = 0.30, p < 0.0001). Significant differences in the severity of trabecular delayed hyperenhancement were detected among patients with mild and those with moderate and severe clinical stage of disease (p < 0.0001). CONCLUSION Cardiac MRI shows trabecular delayed hyperenhancement in left ventricular noncompaction. Evaluating the extent and severity of left ventricular noncompaction and trabecular delayed hyperenhancement may improve the ability of the clinician to predict the clinical stage of disease.

Headshop heartache: acute mephedrone 'meow' myocarditis.

Case study of 19 year old man who presented to hospital with crushing chest pain 20 hours after oral injestion of a gram of plant food containing Mephadrone.

Bronchiolitis obliterans following lung transplantation: early detection using computed tomographic scanning

Background: Computed tomographic (CT) scanning may enable earlier diagnosis of chronic lung allograft dysfunction than forced expiratory volume in 1 second (FEV1). A study was undertaken to determine intra-observer and inter-observer agreement of composite and air trapping CT scores, to examine the association of FEV1 with the composite and air trapping CT score, and to relate the baseline composite CT score to changes in FEV1 and changes in the composite CT score over 1 year. Methods: Lung function and baseline CT scans following transplantation and at subsequent annual follow ups were analysed in 38 lung transplant recipients. Scans were randomly scored by two observers for bronchiectasis, mucus plugging, airway wall thickening, consolidation, mosaic pattern, and air trapping, and re-scored after 1 month. CT scores were expressed on a scale of 0–100 and correlated with FEV1 as a percentage of the post-transplant baseline value. Results: The mean (SD) interval between baseline and follow up CT scans was 11.2 (4.7) months. Inter-observer and intra-observer agreement was good for both the composite and air trapping CT scores. There was a significant association between FEV1 and the composite CT score, with each unit of worsening in the baseline composite CT score predicting a 1.55% and 1.37% worsening in FEV1 over the following year (p<0.0001) and a 1.25 and 1.12 unit worsening in the composite CT score (p<0.0001) for observers 1 and 2, respectively. Conclusion: These findings indicate a potential role for a composite CT scoring system in the early detection of bronchiolitis obliterans.

Coronary stent assessability by 64 slice multi-detector computed tomography.

Background: We evaluated the assessability of contemporary stent platforms by 64‐slice multi‐detector computed tomography (MDCT). Methods. Patients undergoing coronary stenting were included in a prospective protocol of MDCT imaging within 48 hr of stent implantation. MDCT data were acquired using a “Sensation 64” MDCT scanner (Siemens Medical Solutions, Forchheim, Germany). Stent assessability was assessed by two independent blinded observers and disagreement was resolved by a third observer. Assessability was defined at visualization of the in‐stent lumen without influence of partial volume effects, beam hardening, motion, calcification, or contrast to noise limitations. Results: Fifty four stents (Cypher n = 25, Vision/Minivision n = 19, Taxus Express n = 8, Liberte n = 1, Driver n = 1) in 44 patients were included in the study. The two independent observers classified 30 of 54 stents (56%) as assessable. Interobserver reproducibility was good with κ = 0.66. Stent size was the most important determinant of assessability. Consistently assessable stents were 3.0 mm or larger (85%), whereas those under 3 mm were mostly nonassessable (26%).Conclusions: Contemporary stent designs evaluated on a 64‐slice MDCT scanner showed artifact free assessability only in larger stents. Increase in spatial resolution of MDCT scanners or modifications in stent design will be necessary to noninvasive evaluate stents <3 mm in diameter, where in‐stent restenosis is more frequent.

Congenital Anomalies of Coronary Artery Origin in Adults: 64-MDCT Appearance

OBJECTIVE The purpose of this pictorial essay is to review the 64-MDCT appearance of congenital anomalies of the origins of the coronary arteries in adults. CONCLUSION Increasing use of MDCT for cardiac imaging of adults requires familiarity with the cross-sectional appearance of congenital coronary artery anomalies visualized with noninvasive imaging techniques. Many of these anomalies are benign, but a small number are associated with myocardial ischemia and sudden death. Increasing use of MDCT in cardiac imaging may yield diagnostic information not obtained with coronary angiography. Axial, multiplanar, and 3D volume-rendered reconstructions should aid in detection and improve interpretation of such anomalies.

Conventional High-Resolution CT Versus Helical High-Resolution MDCT in the Detection of Bronchiectasis

OBJECTIVE The purpose of this study was to compare conventional high-resolution CT (HRCT) with helical 16-MDCT in the detection of bronchiectasis. MATERIALS AND METHODS We retrospectively evaluated 80 patients including 61 with bronchiectasis (mean age, 64 years; range, 22-87 years) and a control group of 19 patients with normal MDCT of the chest. Two sets of images were blindly, randomly analyzed by two observers: contiguous 1-mm slices (MDCT set) and 1-mm slices every 10 mm (HRCT set) derived from the MDCT set. Images were scored independently for presence, extent, and severity of bronchiectasis, followed by a consensus interpretation. Kappa analysis assessed inter- and intraobserver agreement. MDCT was the radiologic gold standard. RESULTS Of the 61 patients with bronchiectasis diagnosed with MDCT, 56 (92%) were positive for bronchiectasis on conventional HRCT. Seven patients had positive MDCT scans only, and two patients had positive HRCT scans only. Of 479 lobes, 59 were positive for bronchiectasis on MDCT and negative on HRCT, and 19 lobes were positive for bronchiectasis on HRCT and negative on MDCT (p < 0.0001). MDCT showed 25 more lobes with cylindric, 11 more lobes with varicose, and four more lobes with cystic bronchiectasis than did HRCT. Sensitivity, specificity, and positive and negative predictive values of HRCT in detecting bronchiectasis were 71%, 93%, 88%, and 81%, respectively. Interobserver agreement for presence, extent, and severity of bronchiectasis ranged from moderate to good for MDCT (kappa values, 0.64, 0.5, and 0.48, respectively) and poor to good for HRCT (kappa values, 0.65, 0.46, and 0.25, respectively). CONCLUSION Contiguous helical 16-MDCT with 1-mm collimation is superior to HRCT at 10-mm intervals in showing the presence and extent of bronchiectasis.

Evidence-based radiology: how to quickly assess the validity and strength of publications in the diagnostic radiology literature

The aim of this study was to show how evidence-based medicine (EBM) techniques can be applied to the appraisal of diagnostic radiology publications. A clinical scenario is described: a gastroenterologist has questioned the diagnostic performance of magnetic resonance cholangiopancreatography (MRCP) in a patient who may have common bile duct (CBD) stones. His opinion was based on an article on MRCP published in “Gut.” The principles of EBM are described and then applied to the critical appraisal of this paper. Another paper on the same subject was obtained from the radiology literature and was also critically appraised using explicit EBM criteria. The principles for assessing the validity and strength of both studies are outlined. All statistical parameters were generated quickly using a spreadsheet in Excel format. The results of EBM assessment of both papers are presented. The calculation and application of confidence intervals (CIs) and likelihood ratios (LRs) for both studies are described. These statistical results are applied to individual patient scenarios using graphs of conditional probability (GCP). Basic EBM principles are described and additional points relevant to radiologists discussed. Online resources for EBR practice are identified. The principles of EBM and their application to radiology are discussed. It is emphasized that sensitivity and specificity are point estimates of the “true” characteristics of a test in clinical practice. A spreadsheet can be used to quickly calculate CIs, LRs and GCPs. These give the radiologist a better understanding of the meaning of diagnostic test results in any patient or population of patients.

High-resolution MDCT of pulmonary septic embolism: evaluation of the feeding vessel sign.

OBJECTIVE The objective of this study was to use high-resolution MDCT to assess the relation of the pulmonary vasculature to septic emboli with particular attention to the feeding vessel sign. MATERIALS AND METHODS The MDCT scans of nine patients with septic emboli were retrospectively, blindly evaluated by two observers. A control group of 10 patients with documented pulmonary metastasis and pathologically proven carcinoma also were included. Transverse images, multiplanar reconstructions, and maximum intensity projections were used to analyze nodules and the pulmonary vasculature. The CT scans were obtained with 1- to 1.25-mm collimation on a 4-, 8-, or 16-MDCT scanner. The feeding vessel sign was defined as a vessel coursing directly into a nodule. RESULTS The patients with septic embolism had a total of 141 nodules and 52 wedge-shaped opacities. Transverse images showed that 52 (37%) of the nodules and 11 (22%) of the wedge-shaped opacities had a vessel that appeared to enter the nodule, but multiplanar reconstructions (without IV contrast enhancement) and maximum intensity projections (with IV contrast enhancement) showed the vessels passed around the nodules. Twenty-one (15%) of the spherical nodules and seven (13%) of the wedge-shaped opacities exhibited a central vessel entering the lesion in all imaging planes. All of these vessels were traced to the left atrium on transverse images, a finding consistent with pulmonary vein branches. Similar findings were seen in pulmonary metastatic lesions. CONCLUSION Although pulmonary septic emboli often appear to have a feeding vessel on conventional cross-sectional images, multiplanar reconstructions show that most of these vessels course around the nodule and that the others are pulmonary veins.