Vineet R. Jain

Variants and anomalies of thoracic vasculature on computed tomographic angiography in adults.

Objective: To determine the prevalence and clinical significance of normal, variant, and anomalous branching patterns of the aortic arch and the central veins on computed tomographic (CT) angiography in adults. Methods: We retrospectively reviewed 1000 consecutive CT angiograms of the chest in 658 women and 342 men with a median age of 53 years. Results: A total of 65.9% of patients had both normal aortic arch branching patterns and normal venous anatomy. Variants in the aortic arch branching pattern were present in 32.4% and anomalies in 1.5%. Venous anomalies were present in 0.7%. Review of CT reports showed that cardiothoracic radiologists correctly reported the anomaly more frequently than other radiologists (94% vs 20%, P = 0.003). Conclusions: Whereas anomalies of the central thoracic vasculature are uncommon, variants in the aortic arch branching pattern are common. An appreciation of the appearance of these entities on CT angiography allows for precise reporting and is useful in preprocedure planning.

Acute Aortic Syndromes: A Second Look at Dual-Phase CT

OBJECTIVE The purpose of this article is to assess the diagnostic performance of the unenhanced and contrast-enhanced phases separately in patients imaged with CT for suspected acute aortic syndromes. MATERIALS AND METHODS All adults (n = 2868) presenting to our emergency department from January 1, 2006, through August 1, 2010, who underwent unenhanced and contrast-enhanced CT of the chest and abdomen for suspected acute aortic syndrome were retrospectively identified. Forty-five patients with acute aortic syndrome and 45 healthy control subjects comprised the study population (55 women; mean age, 61 ± 16 years). Unenhanced followed by contrast-enhanced CT angiography (CTA) images were reviewed. Contrast-enhanced CTA examinations of case patients and control subjects with isolated intramural hematoma were reviewed. Radiation exposure was estimated by CT dose-length product. RESULTS Forty-five patients had one or more CT findings of acute aortic syndrome: aortic dissection (n = 32), intramural hematoma (n = 27), aortic rupture (n = 10), impending rupture (n = 4), and penetrating atherosclerotic ulcer (n = 2). Unenhanced CT was 89% (40/45) sensitive and 100% (45/45) specific for acute aortic syndrome. Unenhanced CT was 94% (17/18) and 71% (10/14) sensitive for type A and type B dissection, respectively (p = 0.142). Contrast-enhanced CTA was 100% (8/8) sensitive for isolated intramural hematoma. Mean radiation effective dose was 43 ± 20 mSv. CONCLUSION Unenhanced CT performed well in detection of acute aortic syndrome treated surgically, although its performance does not support its use in place of contrast-enhanced CTA. Unenhanced CT may be a reasonable first examination for rapid triage when IV contrast is contraindicated. Contrast-enhanced CTA was highly sensitive for intramural hematoma, suggesting that unenhanced imaging may not always be needed. Acute aortic syndrome imaging protocols should be optimized to reduce radiation dose.

Should CT Play a Greater Role in Preventing the Resection of Granulomas in the Era of PET

OBJECTIVE PET cannot distinguish between bronchogenic carcinoma and granuloma, but positive scans may prompt surgery. We systematically evaluated the CT appearance of resected carcinomas and granulomas to identify features that could be used to reduce granuloma resections. MATERIALS AND METHODS We retrospectively identified 93 consecutive patients between January 2005 and November 2008 who had resection of a pulmonary nodule pathologically diagnosed as bronchogenic carcinoma or granuloma and preoperative imaging with CT and PET. Each nodule was evaluated on CT for size, doubling time, location, borders, shape, internal characteristics, calcification, clustering, air bronchograms, and cavitation. A diagnostic impression was rendered. Bivariate and logistic regression analyses were performed. Pre-PET data regarding the proportion of resected granulomas and carcinomas between January 1995 and December 1996 were reviewed. RESULTS Sixty-eight percent (65/96) of nodules were carcinomas and 32% (31/96) were granulomas. The CT impression was benign in 65% (20/31) of granulomas and 5% (3/65) of carcinomas (p < 0.0001; negative predictive value [NPV], 87% [20/23]). Specific CT features significantly associated with granuloma were clustering, cavitation, irregular shape, lack of pleural tags, and solid attenuation. The combination of nonspiculated borders, irregular shape, and solid attenuation had an NPV of 86% (12/14). Granulomas represented 18% (9/50) of resected nodules in 1995 and 1996 (p = 0.066). CONCLUSION CT findings reduce but cannot eliminate the possibility that a nodule is malignant. Outcomes-based clinical trials are needed to determine whether CT features of benignity can guide less-invasive initial management and reverse a concerning trend in granuloma resection.

Pulmonary atelectasis in children anesthetized for cardiothoracic MR: Evaluation of risk factors

Purpose: To systematically assess the frequency and risk factors for atelectasis in children anesthetized for cardiothoracic magnetic resonance (MR). Materials and Methods We retrospectively identified 58 consecutive children (age range, 6 days to 21 years) who underwent cardiothoracic MR from January 2001 to December 2004 whose imaging and medical charts were available. One certificate of added qualification pediatric radiologist and 1 of 2 cardiothoracic radiologists, in consensus, evaluated the first and last set of axial images. Images were evaluated for cardiac, vascular and tracheobronchial abnormalities, and degree of atelectasis. Atelectasis was considered significant if the equivalent of 3 or more segments were involved. Patients received 1 or more of 7 anesthetic medications (n = 27), chloral hydrate alone (n = 4), or required no anesthesia (n = 27). Results: Significant atelectasis developed only in those receiving anesthetic medications. Thirty-seven percent (10/27) of anesthetized children developed significant atelectasis in the first and/or last axial sequence. In 90% (9 /10) of patients, it developed in the first axial sequence. Strong risk factors were age younger than 1 year (80%, 8/10, P = 0.029) and MR evidence of tracheobronchial narrowing (50%, 5/10, P = 0.008). In patients with vascular ring, there was a trend toward significance (40%, 4/10, P = 0.09). None of the anesthesia factors were significant, including ventilation mode, anesthesia duration, or American Society of Anesthesiology risk (all P > 0.1). Conclusions: Atelectasis may occur shortly after induction of anesthesia in children younger than 1 year of age or with tracheobronchial narrowing when anesthetized for cardiothoracic MR.

Imaging of left ventricular assist devices.

Abstract: Left ventricular assist devices are used as a bridge to recovery, a bridge to transplant, or a permanent alternative to cardiac transplant. This exhibit demonstrates the imaging appearance of commonly used left ventricular assist devices and their complications.

Resting Cardiac 64-MDCT Does Not Reliably Detect Myocardial Ischemia Identified by Radionuclide Imaging

OBJECTIVE CT myocardial perfusion imaging is an emerging diagnostic modality that is under intensive study but not yet widely used in clinical practice. The purpose of this study is to evaluate the performance of resting 64-MDCT in revealing ischemia identified on radionuclide myocardial perfusion imaging (MPI). MATERIALS AND METHODS We retrospectively identified 35 patients (20 women and 15 men; mean age, 52 years) with myocardial ischemia found on MPI who underwent retrospectively gated CT within 90 days of MPI. Myocardial perfusion on CT was evaluated using both a visual (n = 35) and an automated (n = 34) method. For the visual method, myocardial segments were evaluated qualitatively in systole and diastole. For the automated method, subendocardial perfusion of the standard 17 American Heart Association segments was measured using a commercially available tool in both systole and diastole. Differences between systolic and diastolic perfusion were computed. RESULTS Five hundred eighty myocardial segments were evaluated, 152 of which were ischemic on MPI. Visual analysis had a sensitivity of 16% (24/152), specificity of 92% (393/428), positive predictive value of 40% (24/60), and negative predictive value of 75% (392/520) in systole, and a sensitivity of 18% (27/152), specificity of 89% (382/428), positive predictive value of 37% (27/73), and negative predictive value of 75% (382/507) in diastole, as compared with MPI. There was no significant difference in subendocardial perfusion between ischemic and nonischemic segments by the automated method. There was no significant difference in CT perfusion between patients with and without obstructive coronary artery disease on CT angiography using the visual or automated methods. CONCLUSION Resting 64-MDCT is unsuitable for clinical use in revealing ischemia seen on MPI.

Coronary sinus compression: an early computed tomographic sign of cardiac tamponade.

Objective: To determine retrospectively the distinguishing features of cardiac tamponade on conventional chest computed tomography (CT). Materials and Methods Blinded retrospective analysis of CT scans from 14 patients (6 women, 8 men; age range, 49-93 yrs; mean age, 71 yrs) with echocardiographic evidence of tamponade and 15 controls (11 women, 4 men; age range, 37-96 yrs; mean age, 66 yrs) without tamponade was performed by 3 cardiothoracic radiologists. Computed tomographic scans were analyzed for right ventricular flattening, contrast reflux into the azygos vein, and coronary sinus compression. Inferior vena cava (IVC) and superior vena cava short-axis diameter and pericardial fluid attenuation were recorded. If the pericardium or pericardial fluid was sampled, results were noted. Case and control group variables were compared using the Fisher exact test and the t test. Results were also subjected to logistic regression analysis. Results: Coronary sinus compression was present in 46% (6/13) patients with tamponade and in no controls (P = 0.006). Trends toward IVC dilatation and elevation of pericardial fluid attenuation in cases of tamponade did not reach statistical significance. A specific pathological diagnosis was made in 88% (7/8) of tamponade cases and 29% (2/7) of controls (P = 0.04). Conclusions: The detection of coronary sinus compression on CT is an early specific indicator of cardiac tamponade. Dilatation of the IVC and the presence of elevated pericardial fluid attenuation are CT signs suggestive of the diagnosis.

Retained fibrin sheaths: chest computed tomography findings and clinical associations.

Purpose: Fibrin sheaths may develop around long-term indwelling central venous catheters (CVCs) and remain in place after the catheters are removed. We evaluated the prevalence, computed tomographic (CT) appearance, and clinical associations of retained fibrin sheaths after CVC removal. Materials and Methods: We retrospectively identified 147 adults (77 men and 70 women; mean age 58 y) who underwent CT after CVC removal. The prevalence of fibrin sheath remnants was calculated. Bivariate and multivariate analyses were performed to assess for associations between sheath remnants and underlying diagnoses leading to CVC placement; patients’ age and sex; venous stenosis, occlusion, and collaterals; CVC infection; and pulmonary embolism. Results: Retained fibrin sheaths were present in 13.6% (20/147) of cases, of which 45% (9/20) were calcified. Bivariate analysis revealed sheath remnants to be more common in women than in men [23% (16/70) vs. 5% (4/77), P=0.0018] and to be more commonly associated with venous occlusion and collaterals [30% (6/20) vs. 5% (6/127), P=0.0001 and 30% (6/20) vs. 6% (7/127), P=0.0003, respectively]. Other variables were not associated. Multivariate analysis confirmed the relationship between fibrin sheaths and both female sex (P=0.005) and venous occlusion (P=0.01). Conclusions: Retained fibrin sheaths were seen on CT in a substantial minority of patients after CVC removal; nearly half of them were calcified. They were more common in women and associated with venous occlusion.

Evaluation of the cardiac chambers on axial CT: comparison with echocardiography.

Objective To evaluate qualitative and simple quantitative measures of all 4 cardiac chamber sizes on computed tomography (CT) in comparison with transthoracic echocardiography (TTE). Methods We retrospectively identified 104 adults with electrocardiographically gated cardiac CT and TTE within 3 months. Axial early diastolic (75% R-R) CT images were reviewed for qualitative chamber enlargement, and each chamber was measured linearly. Transthoracic echocardiography was reviewed for linear, area, and volume measurements. Interrater agreement was calculated using Cohen &kgr; and Pearson correlation. Results There were significant correlations between linear left atrium and left ventricle sizes by CT and TTE (r = 0.686 and r = 0.709, respectively). Correlations for right atrium and right ventricle measurements were lower (r = 0.447 and r = 0.492, respectively). Agreement between CT and TTE for qualitative chamber enlargement was poor (highest &kgr; = 0.35). Computed tomography sensitivity was ⩽ 62% for enlargement of all chambers. Conclusions Linear CT measurements of left-sided chamber sizes correlate well with TTE. Right heart measurements and qualitative assessments agreed poorly with TTE.

A Man With a Horseshoe Adrenal Gland Associated With a Midline Posterior Diaphragmatic Defect

We present a case of a horseshoe adrenal gland and a posterior midline diaphragmatic defect found incidentally on computed tomography in a 60-year-old man. It is, to our knowledge, the first case in an adult and represents a relatively innocuous developmental abnormality when compared with the previously described fetal and infantile adrenal fusion syndrome. This case demonstrates the importance of cross-sectional imaging and the effectiveness of computed tomography in defining the spectrum of congenital anomalies.