Diana Litmanovich

CT and MRI in Diseases of the Aorta

OBJECTIVE This review focuses on the role of CT and MRI in the diagnosis, follow-up, and surgical planning of aortic aneurysms and acute aortic syndromes, including aortic dissection, intramural hematoma, and penetrating aortic ulcer. It also provides a systematic approach to the definition, causes, natural history, and imaging principles of these diseases. CONCLUSION An understanding of the pathophysiology, natural history, and imaging features is the key to successful diagnosis and appropriate management of patients with these aortic diseases.

Quality Initiatives Imaging Pregnant Patients with Suspected Pulmonary Embolism: What the Radiologist Needs to Know

Pregnancy is associated with a fivefold increase in the prevalence of venous thromboembolism, and pulmonary embolism is a leading cause of maternal death. However, the diagnosis of pulmonary embolism during pregnancy is challenging because classic clinical symptoms are often absent and physiologic changes during pregnancy can mimic pulmonary embolism. Concerns about exposure of the fetus to ionizing radiation and intravenously administered contrast material, as well as potential medicolegal issues, further complicate the diagnosis. Although diagnostic imaging plays an important role in this setting, there are currently no widely accepted guidelines for radiologists and clinicians to follow. Thus, radiologists should be familiar with the advantages and disadvantages of available imaging modalities, methods for dose reduction, radiation risks, and medicolegal risk management guidelines.

16-MDCT coronary angiography versus invasive coronary angiography in acute chest pain syndrome: a blinded prospective study.

OBJECTIVE The purpose of our study was to prospectively evaluate the usefulness of CT coronary angiography versus invasive coronary angiography for the detection of clinically significant coronary artery disease in patients hospitalized for acute chest pain syndrome. SUBJECTS AND METHODS Sixty-six consecutive patients (52 men and 14 women; average age, 57 +/- 11 [SD] years) who were hospitalized for acute chest pain syndrome underwent CT coronary angiography and invasive coronary angiography within an average time interval of 4 days. ECG-gated CT coronary angiography was performed with a 16-MDCT scanner (0.42-sec rotation time, 16 x 0.75 mm detector collimation). Beta-blockers were not administered routinely, and thus the average heart rate was 71 +/- 11 beats per minute. CT coronary angiographic images were evaluated concurrently by two radiologists, who were blinded to invasive coronary angiography results, for stenoses having a diameter of 50% or more, using a 15-segment classification, including all segments 2 mm or more in diameter. The consensus interpretation was compared with results of invasive coronary angiography. RESULTS CT coronary angiography was technically successful in 59 patients (89%). After exclusion of 20 (3.1%) of 649 coronary segments, which were classified as nonevaluable by CT coronary angiography, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of CT coronary angiography for identifying significant coronary artery disease in the remaining 629 coronary segments were 80% (68/85), 89% (482/544), 52% (68/130), 97% (482/499), and 87% (550/629), respectively. The overall accuracy for the main vessels (left main, left anterior descending, left circumflex, and right coronary arteries) was 93%, 88%, 86%, and 86%, respectively. CONCLUSION CT coronary angiography using a 16-MDCT scanner enables accurate noninvasive detection of significant coronary artery disease in patients hospitalized for acute chest pain syndrome. Furthermore, relative high sensitivity and specificity of CT coronary angiography can be achieved without pharmacologic manipulation of patient heart rates.

CT of pulmonary emphysema - current status, challenges, and future directions

Pulmonary emphysema is characterized by irreversible destruction of lung parenchyma. Emphysema is a major contributor to chronic obstructive pulmonary disease (COPD), which by itself is a major cause of morbidity and mortality in the western world. Computed tomography (CT) is an established method for the in-vivo analysis of emphysema. This review first details the pathological basis of emphysema and shows how the subtypes of emphysema can be characterized by CT. The review then shows how CT is used to quantify emphysema, and describes the requirements and foundations for quantification to be accurate. Finally, the review discusses new challenges and their potential solution, notably focused on multi-detector-row CT, and emphasizes the open questions that future research on CT of pulmonary emphysema will have to address.

Multidetector CT evaluation of tracheobronchomalacia.

Tracheobronchomalacia (TBM) refers to excessive expiratory collapse of the trachea and bronchi as a result of weakening of the airway walls and/or supporting cartilage. This disorder has recently been increasingly recognized as an important cause of chronic respiratory symptoms. Multidetector CT (MDCT) technology allows for noninvasive imaging of TBM with similar accuracy to the historical reference standard of bronchoscopy. Paired end-inspiratory, dynamic expiratory MDCT is the examination of choice for assessing patients with suspected TBM. Radiologists should become familiar with imaging protocols and interpretation techniques to accurately diagnose this condition using MDCT.

Dose Reduction in Computed Tomographic Angiography of Pregnant Patients With Suspected Acute Pulmonary Embolism

Purpose: The aim of this study was to quantify the effect of a reduced-dose pulmonary computed tomographic (CT) angiography protocol on radiation dose and image quality in pregnant patients as compared with a standard protocol. Materials and Methods: Twenty-six pregnant women with suspected pulmonary embolism underwent reduced-dose CT angiography (200 mA and 100 kV, from the aortic arch to the diaphragm). The matched control group standard protocol was 400 mA, 120 kilovolt (peak), and the entire thorax. The CT dose index, dose-length product, effective dose, image quality, and signal-to-noise ratio were assessed and compared with the Wilcoxon rank sum test result. Results: The CT dose index, mean dose-length product, and calculated effective dose were lower in the pregnancy group than in the controls: mean (SD), 5.21 (1.54) mGy versus 20.86 (5.59) mGy; 105.65 (39.77) mGy cm versus 575.71 (154.86) mGy cm, and 1.79 (0.676) msv versus 9.787 (2.63) msv, respectively (P < 0.0001). Quality scores of segmental (P = 0.266) and subsegmental (P = 0.207) arteries and arterial attenuation (P = 0.443) were similar. Conclusions: In pregnant patients with suspected pulmonary embolism, combined reduction of kilovoltage and milliampere-second settings and z-axis coverage results in a substantial reduction of radiation dose while maintaining diagnostic imaging quality.

Sonographic detection of pneumothorax by radiology residents as part of extended focused assessment with sonography for trauma.

Objective. The purpose of this study was to assess the accuracy of sonographic pneumothorax detection by radiology residents as a part of extended focused assessment with sonography for trauma (eFAST). Methods. In a prospective study, a sonographic search for pneumothoraces was performed as part of a standard FAST examination by the on‐call resident. Each lung field was scanned at the second to fourth anterior intercostal spaces and the sixth to eighth midaxillary line intercostal spaces. A normal pleural interface was identified by the presence of parietal‐over‐visceral pleural sliding with “comet tail” artifacts behind. Absence of these normal features indicated a pneumothorax. The sonographic diagnosis was correlated with supine chest radiography and chest computed tomography (CT). Results. A total of 338 lung fields in 169 patients were included in the study. Patients underwent eFAST, chest radiography, and chest CT when clinically indicated. Chest CT was considered the reference standard examination. Computed tomography identified 43 pneumothoraces (13%): 34 small and 9 moderate. On chest radiography, 7 pneumothoraces (16%) were identified. Extended FAST identified 23 pneumothoraces (53%). Compared with CT, eFAST had sensitivity of 47%, specificity of 99%, a positive predictive value of 87%, and a negative predictive value of 93%. All of the moderate pneumothoraces were identified by eFAST. Twenty small pneumothoraces missed by eFAST did not require drainage during the hospitalization period. Conclusions. Extended FAST performed by residents is an accurate and efficient tool for early detection of clinically important pneumothoraces.

Imaging in Transcatheter Aortic Valve Replacement (TAVR): role of the radiologist

BackgroundTranscatheter aortic valve replacement (TAVR) is a novel technique developed in the last decade to treat severe aortic stenosis in patients who are non-surgical candidates because of multiple comorbidities.MethodsSince the technique is performed using a transvascular approach, pre-procedural assessment of the aortic valve apparatus, ascending aorta and vascular access is of paramount importance for both appropriate patient selection and correct device selection. This assessment is performed by a multi-disciplinary team with radiology being an integral and important part.ResultsAmong imaging modalities, there is growing scientific evidence supporting the crucial role of MDCT in the assessment of the aortic valve apparatus, suitability of the iliofemoral or alternative pathway, and determination of appropriate coaxial angles. MDCT also plays an important role in post-procedure imaging in the assessment of valve integrity and position.ConclusionThis review outlines the principal aspects of TAVR, the multidisciplinary approach and utilisation of different imaging modalities, as well as a step-by-step approach to MDCT acquisition protocols, reconstruction techniques, pre-procedure measurements and post-procedure assessment.Teaching Points• TAVR is a new technique to treat severe aortic stenosis in high-risk and nonsurgical candidates.• MDCT assessment of the aortic annulus is important for appropriate patient and device selection.• Multidisciplinary approach is required for patient selection, procedure planning and performance.• MDCT is required for assessment of the aortic root, iliofemoral or alternative vascular pathway.

Dynamic Expiratory Tracheal Collapse in Morbidly Obese COPD Patients

Abstract Morbid obesity may influence several aspects of airway function. However, the effect of morbid obesity on expiratory tracheal collapse in COPD patients is unknown. We thus prospectively studied 100 COPD patients who underwent full pulmonary function tests (PFTs), 6-minute walk test (6MWT), Saint Georges Respiratory Questionnaire (SGRQ), and low-dose CT at total lung capacity and during dynamic exhalation with spirometric monitoring. We examined correlations between percentage dynamic expiratory tracheal collapse and body mass index (BMI). The association between tracheal collapse and BMI was compared to a control group of 53 volunteers without COPD. Patients included 48 women and 52 men with mean age 65 ± 7 years; BMI 30 ± 6; FEV1 64 ± 22% predicted and percentage expiratory collapse 59 ± 19%. Expiratory collapse was significantly associated with BMI (69 ± 12% tracheal collapse among 20 morbidly obese patients with BMI ≥35 compared to 57 ±19% in others, p = 0.002, t-test). In contrast, there was no significant difference in collapse between healthy volunteers with BMI ≥ 35 and < 35. COPD patients with BMI ≥ 35 also demonstrated shorter 6MWT distances (340 ± 139 m vs. 430 ± 139 m, p = 0.003) and higher (worse) total SGRQ scores (48 ± 19 vs. 36 ± 20, p = 0.013) compared to those with BMI < 35. In light of these results, clinicians should consider evaluating for excessive expiratory tracheal collapse when confronted with a morbidly obese COPD patient with greater quality of life impairment and worse exercise performance than expected based on functional measures.

Insights into imaging of aortitis

BackgroundAortitis is a subtype of the more general term “vasculitis”, an inflammatory condition of infectious or noninfectious origin involving the vessel wall. The term “vasculitis” refers to a broad spectrum of diseases with different aetiologies, pathophysiologies, clinical presentations and prognoses. The clinical manifestations are nonspecific, as are the laboratory findings such as pain, fever, weight loss, vascular insufficiency and elevated levels of acute phase reactants, as well as other systemic manifestations, and sometimes may mimic other entities. Thus, if not suspected as part of the initial differential diagnosis, aortitis can be overlooked during the workup of patients with constitutional symptoms and systemic disorders. Methods: Imaging is rarely used for the primary diagnosis, but imaging findings, although nonspecific, can help in the assessment of these patients and is often required for making the final diagnosis. Imaging can be critical in the initiation of appropriate management and therapy. Results: Noninvasive cross-sectional imaging modalities such as contrast-enhanced CT, magnetic resonance (MR) imaging, nuclear medicine and in particular positron emission tomography (PET) are the leading modalities in modern diagnostic imaging of aortitis for both the initial diagnosis and follow-up. Conclusion: This review focusses on the most common manifestations of aortitis with which radiologists should be familiar.Teaching Points• Aortitis is an inflammatory condition of infectious/noninfectious origin involving the vessel wall.• Imaging findings can help in the assessment of aortitis and are often crucial for the final diagnosis.• Contrast-enhanced CT, MRI and PET-CT are used for both the initial diagnosis and follow-up of aortitis.