The Importance of Imaging in the Assessment of Interstitial Lung Diseases.

High-resolution computed tomography (HRCT) is an essential component of the diagnosis and assessment of patients with interstitial lung diseases (ILDs). In some cases, a diagnosis of ILD can be made solely based on a multidisciplinary discussion of HRCT findings and clinical evaluation. HRCT findings also inform prognosis and may influence treatment decisions. It is essential that high-quality HRCT images are obtained using parameters for optimum spatial resolution. Key terms used to describe HRCT findings should be used consistently among clinicians. Radiologic information should be included as part of the multidisciplinary discussion of patients with ILDs during follow-up.

Approaches to Greening Radiology.

The health care sector is a resource-intensive industry, consuming significant amounts of water and energy, and producing a multitude of waste. Health care providers are increasingly implementing strategies to reduce energy use and waste. Little is currently known about existing sustainability strategies and how they may be supported by radiology practices. Here, we review concepts and ideas that minimize energy use and waste, and that can be supported or implemented by radiologists.

Impact of pixel value truncation on image quality of low dose chest CT.

PURPOSE: In some noisy low dose CT lung cancer screening images, we noticed that the CT density values of air were increased and the visibility of emphysema was distinctly decreased. By examining histograms of these images, we found that the CT density values were truncated at -1024 HU. The purpose of this study was to investigate the effect of pixel value truncation on the visibility of emphysema using mathematical models. METHODS AND MATERIALS: Assuming CT noise follows a normal distribution, we derived the relationship between the mean CT density value and the standard deviation (SD) when the pixel values below -1024 HU are truncated and replaced by -1024 HU. To validate our mathematical model, 20 untruncated phantom CT images were truncated by simulation, and the mean CT density values and SD of air in the images were measured and compared with the theoretical values. In addition, the mean CT density values and SD of air were measured in 100 cases of real clinical images obtained by GE, Siemens, and Philips scanners, respectively, and the agreement with the theoretical values was examined. Next, the contrast-to-noise ratio (CNR) between air (-1000 HU) and lung parenchyma (-850 HU) was derived from the mathematical model in the presence and absence of truncation as a measure of the visibility of emphysema. In addition, the radiation dose ratios required to obtain the same CNR in the case with and without truncation were also calculated. RESULTS: The mathematical model revealed that when the pixel values are truncated, the mean CT density values are proportional to the noise magnitude when the magnitude exceeds a certain level. The mean CT density values and SD measured in the images with pixel values truncated by simulation and in the real clinical images acquired by GE and Philips scanners agreed well with the theoretical values from our mathematical model. In the Siemens images, the measured and theoretical values agreed well when a portion of the truncated values were replaced by random values instead of simply replacing by -1024 HU. The CNR of air and lung parenchyma was lowered by truncating CT density values compared to that of no truncation. Furthermore, it was found that higher radiation dose was required to obtain the same CNR with truncation as without. As an example, when the noise SD was 60 HU, the radiation dose required for the GE and Philips truncation method was about 1.2 times higher than that without truncation, and that for the Siemens truncation method was about 1.4 times higher. CONCLUSIONS: It was demonstrated mathematically that pixel value truncation causes a brightening of the mean CT density value and decreases the CNR of emphysema. Our results indicate that it is advisable to turn off truncation at -1024 HU, especially when scanning at low and ultra-low radiation doses in the thorax.

Radiology, Mobile Devices, and Internet of Things (IoT).

Radiology by its nature is intricately connected to the Internet and is at the forefront of technology in medicine. The past few years have seen a dramatic rise in Internet-based technology in healthcare, with imaging as a core application. Numerous Internet-based applications and technologies have made forays into medicine, and for radiology it is more seamless than in other clinical specialties. Many applications in the practice of radiology are Internet based and more applications are being added every day. Introduction of mobile devices and their integration into imaging workflow has reinforced the role played by the Internet in radiology. Due to the rapid proliferation of wearable devices and smartphones, IoT-enabled technology is evolving healthcare from conventional hub-based systems to more personalized healthcare systems. This article briefly discusses how the IoT plays a useful role in daily imaging workflow and current and potential future applications, how mobile devices can be integrated into radiology workflows, and the impact of the IoT on resident and medical student education, research, and patient engagement in radiology.

Reductions in High-End Imaging Utilization With Radiology Review and Consultation.

Following the uptake of value-based purchasing in concert with health care reform in the United States, providers, insurers, and patients are looking for ways to reduce excessive, dangerous, and/or inappropriate high-end imaging utilization (HEIU). Inappropriate HEIU is associated with patient safety risks due to unnecessary exposure to radiation, misappropriation of scarce equipment resources and staff, complications to clinical care, and needless, excessive costs for the patient, hospital, and payer. This paper presents a cost-effective radiology-initiated improvement program piloted in the Christiana Hospital Coordinated Care Network. The pilot demonstrated the effectiveness of regulating high-end imaging orders through radiologists' review of requests of the order as part of the consult process. Over the 2014-2015 fiscal year, 2,177 high-end imaging orders were reviewed by 26 radiologists for approval, rejection, or recommendation of an alternate examination. Of the orders, 86.7% (1887) were approved, 4.0% (87) were rejected, and 9.3% (203) received recommendation for an alternate examination. Based on improved patient safety, cost savings, and appropriate resource use, these findings suggest that radiologists' review can effectively reduce excessive HEIU. This method, with an appropriate algorithm to assist with handling a larger volume of orders, would be ideal to implement systemwide to manage HEIU cost efficiency, simultaneously providing radiologists with more control in their area of expertise and positively impacting quality, safety, and value-based purchasing goals.

Osteoprotegerin is a Better Serum Biomarker of Coronary Artery Calcification than Osteocalcin in Type 2 Diabetes.

OBJECTIVE: Coronary artery calcification (CAC) is a prominent feature of atherosclerosis and is associated with cardiovascular events. In vitro studies have suggested that osteoprotegerin (OPG) and osteocalcin (OC) exert anticalcification potential in the vessel wall. The objective of this study was to investigate the association of CAC and serum bone biomarkers in persons with type 2 diabetes. METHODS: We examined 50 individuals with type 2 diabetes. CAC imaging was performed by multidetector computed tomography. CAC scores ≥10, expressed in Agatston units, were considered abnormal. OC, undercarboxylated OC (ucOC), and OPG levels were determined by enzyme-linked immunosorbent assay. RESULTS: Abnormal CAC scores were found for 64% of the study cohort. OPG levels were significantly elevated (5.5 ± 2.0 pmol/L vs. 4.2 ± 1.7 pmol/L; P = .026) for those with abnormal CAC scores. No univariate differences were found for OC or ucOC. Logistic regression analyses revealed that an increase in serum OPG level was significantly associated with an increase in CAC score (odds ratio, 3.324; 95% confidence interval, 1.321 to 8.359; P = .011). Longer duration of diabetes was a significant covariate (P = .026), whereas nonsignificant covariates in the final model were age, gender, systolic blood pressure, body mass index, insulin resistance determined by the homeostasis model assessment for insulin resistance, leptin, adiponectin, and glycemic control. The Nagelkerke R2 for the model was 0.66. Neither OC nor ucOC were significantly associated with elevated CAC scores. CONCLUSION: Our results suggest that OPG is a more useful serum biomarker than OC or ucOC for identifying those at increased risk of arterial calcification in type 2 diabetes.

Cholecystocolonic fistula.

Cholecystoenteric fistulas are a complication of biliary disease, having an estimated incidence in the range of 0.1 - 0.5 percent. Roughly 8-27 percent of these are of the cholecystocolonic type,1 occurring most commonly at the hepatic flexure. An 82-year-old male presented to our tertiary hospital emergency department and was diagnosed with a cholecystocolonic fistula (CCF) by CT imaging. Surgical evaluation confirmed the CT diagnosis with subsequent removal of the fistula and gallbladder, which was curative.

Effect of left atrial circumferential ablation for atrial fibrillation on left atrial transport function.

BACKGROUND: The effects of left atrial (LA) circumferential ablation on LA function in patients with atrial fibrillation (AF) have not been well described. OBJECTIVES: The purpose of this study was to determine the effect of LA circumferential ablation on LA function. METHODS: Gated, multiphase, dynamic contrast-enhanced computed tomographic (CT) scans of the chest with three-dimensional reconstructions of the heart were used to calculate the LA ejection fraction (EF) in 36 patients with paroxysmal (n = 27) or chronic (n = 9) AF (mean age 55 +/- 11 years) and in 10 control subjects with no history of AF. Because CT scans had to be acquired during sinus rhythm, a CT scan was available both before and after (mean 5 +/- 1 months) LA circumferential ablation (LACA) in only 10 patients. A single CT scan was acquired in 8 patients before and in 18 patients after LACA ablation. Radiofrequency catheter ablation was performed using an 8-mm-tip catheter to encircle the pulmonary veins, with additional lines along the mitral isthmus and the roof. RESULTS: In patients with paroxysmal AF, LA EF was lower after than before LACA (21% +/- 8% vs 32 +/- 13%, P = .003). LA EF after LA catheter ablation was similar among patients with paroxysmal AF and those with chronic AF (21% +/- 8% vs 23 +/- 13%, P = .7). However, LA EF after LA catheter ablation was lower in all patients with AF than in control subjects (21% +/- 10% vs 47% +/- 5%, P < .001). CONCLUSION: During medium-term follow-up, restoration of sinus rhythm by LACA results in partial return of LA function in patients with chronic AF. However, in patients with paroxysmal AF, LA catheter ablation results in decreased LA function. Whether the impairment in LA function is severe enough to predispose to LA thrombi despite elimination of AF remains to be determined.

Topographic analysis of the coronary sinus and major cardiac veins by computed tomography.

BACKGROUND: The coronary sinus (CS) and its branches may play a role in the genesis of various arrhythmias. Applications of radiofrequency energy within the CS may be necessary. Atrio-esophageal fistula has been recognized as a complication of ablation along the posterior left atrial wall. OBJECTIVES: The purpose of this study was to describe the in vivo topographic anatomy of the CS, esophagus, and coronary arteries using computed tomography (CT). METHODS: Helical contrast CT of the heart with three-dimensional and endoscopic reconstructions was performed in 50 patients (28 men and 22 women; mean age 54 +/- 10 years). The images were reformatted to determine the relationships among the CS, adjacent blood vessels, and esophagus and to determine the nature and thickness of surrounding tissue layers. RESULTS: Mean CS ostium diameter was 12 +/- 4 mm, and mean thickness of the periosteal fat layer was 3 +/- 2 mm. In 40 of the 50 patients (80%), the esophagus was adjacent to the CS, starting 24 +/- 9 mm from the ostium, and remained in contact for a mean length of 7 +/- 5 mm. Mean thickness of the fat layer between the esophagus and CS was 1 +/- 1 mm, and mean thickness of the anterior wall of the esophagus was 3 +/- 2 mm. In 10 patients (20%), there was no contact between the esophagus and CS. In 40 patients (80%), the right coronary artery was less than 5 mm from the CS (minimum distance 1 +/- 1 mm) over a mean length of 17 +/- 11 mm. In all patients, the circumflex artery was less than 5 mm from the CS (minimum distance 1 +/- 0.4 mm) over a mean length of 16 +/- 9 mm in patients with right-dominant coronary circulation and over a mean length of 86 +/- 11 mm in patients with left-dominant coronary circulation. CONCLUSION: The CS often lies very close to the esophagus and coronary arteries. During radiofrequency energy ablation in the CS, caution should be exercised to prevent injury to surrounding structures.

Computed tomographic analysis of the anatomy of the left atrium and the esophagus: implications for left atrial catheter ablation.

BACKGROUND: During left atrial (LA) catheter ablation, an atrioesophageal fistula can develop as a result of thermal injury of the esophagus during ablation along the posterior LA. No in vivo studies have examined the relationship of the esophagus to the LA. The purpose of this study was to describe the topographic anatomy of the esophagus and the posterior LA by use of CT. METHODS AND RESULTS: A helical CT scan of the chest with 3D reconstruction was performed in 50 patients (mean age, 54+/-11 years) with atrial fibrillation before an ablation procedure. Consecutive axial and sagittal sections of the CT scan were examined to determine the relationship, size, and thickness of the tissue layers between the LA and the esophagus. The mean length and width of the esophagus in contact with the posterior LA were 58+/-14 and 13+/-6 mm, respectively. The esophagus had a variable course along the posterior LA. The esophagus was close (10+/-6 mm from the ostia) and parallel to the left-sided pulmonary veins (PVs) in 56% of patients and had an oblique course from the left superior PV to the right inferior PV in 36% of patients. The mean thicknesses of the posterior LA and anterior esophageal walls were 2.2+/-0.9 and 3.6+/-1.7 mm, respectively. In 98% of patients, there was a fat layer between the esophagus and the posterior LA. However, this layer was often discontinuous. CONCLUSIONS: The esophagus and posterior LA wall are in close contact over a large area that may often lie within the atrial fibrillation ablation zone, and there is marked variation in the anatomic relationship of the esophagus and the posterior LA. Both the esophageal and atrial walls are quite thin. However, a layer of adipose tissue may serve to insulate the esophagus from thermal injury, explaining why atrioesophageal fistulas are rare.

Effects of left atrial ablation of atrial fibrillation on size of the left atrium and pulmonary veins.

OBJECTIVES: The purpose of this study was to determine the effect of left atrial circumferential ablation on the size of the left atrium and pulmonary veins (PVs). BACKGROUND: The long-term effects of left atrial circumferential ablation on left atrial and PV size and anatomy have not been analyzed in quantitative fashion. METHODS: PV and left atrial sizes were analyzed in 41 consecutive patients (mean age 54 +/- 12 years) with paroxysmal (n = 25) or chronic (n = 16) atrial fibrillation. Computed tomography of the chest with three-dimensional reconstruction was performed before and 4 +/- 2 months after left atrial circumferential ablation. Left atrial circumferential ablation was performed to encircle the PVs 1 to 2 cm from the ostia, using a power output of 70 W. Additional ablation lines were created in the posterior left atrium and mitral isthmus. Radiofrequency energy also was delivered within the circles and at the PV ostia in 51% of patients at a reduced power output of 35 W. RESULTS: At 6 months, 36 patients (88%) were in sinus rhythm without antiarrhythmic drug therapy, including 3 patients (7%) who developed persistent left atrial flutter and underwent subsequent successful ablation of atrial flutter. There was a 15 +/- 16% decrease in left atrial volume (P < .01) and 10 +/- 35% decrease in PV ostial area (P < .01), without focal narrowing, in patients with a successful outcome. Focal PV stenosis did not occur in any of the 41 patients. CONCLUSIONS: Maintenance of sinus rhythm after left atrial circumferential ablation is associated with reduced left atrial and PV ostial size. Left atrial circumferential ablation for atrial fibrillation does not cause PV stenosis.

Anatomy of the pulmonary veins in patients with atrial fibrillation and effects of segmental ostial ablation analyzed by computed tomography.

INTRODUCTION: The anatomic arrangement of pulmonary veins (PVs) is variable. No prior studies have quantitatively analyzed the effects of segmental ostial ablation on the PVs. The aim of this study was to determine the effect of segmental ostial radiofrequency ablation on PV anatomy in patients with atrial fibrillation (AF). METHODS AND RESULTS: Three-dimensional models of the PVs were constructed from computed tomographic (CT) scans in 58 patients with AF undergoing segmental ostial ablation to isolate the PVs and in 10 control subjects without a history of AF. CT scans were repeated approximately 4 months later. PV and left atrial dimensions were measured with digital calipers. Four separate PV ostia were present in 47 subjects; 3 ostia were present in 2 subjects; and 5 ostia were present in 9 subjects. The superior PVs had a larger ostium than the inferior PVs. Patients with AF had a larger left atrial area between the PV ostia and larger ostial diameters than the controls. Segmental ostial ablation resulted in a 1.5 +/- 3.2 mm narrowing of the ostial diameter. A 28% to 61% focal stenosis was present 7.6 +/- 2.2 mm from the ostium in 3% of 128 isolated PVs. There were no instances of symptomatic PV stenosis during a mean follow-up of 245 +/- 105 days. CONCLUSION: CT of the PVs allows identification of anatomic variants prior to catheter ablation procedures. Segmental ostial ablation results in a significant but small reduction in ostial diameter. Focal stenosis occurs infrequently and is attributable to delivery of radiofrequency energy within the PV.

Cardiovascular MR imaging: technique optimization and detection of disease in clinical practice.

Magnetic resonance (MR) imaging has emerged as an important and growing means of cardiovascular imaging, with many advantages over other radiologic modalities, including excellent spatial and temporal resolution, lack of ionizing radiation, and noninvasiveness. In this article, the utility of MR imaging in cardiovascular imaging and in the diagnosis of cardiovascular disease will be discussed. MR techniques for evaluating the heart and vasculature will be described, and troubleshooting techniques will be presented. Imaging findings in congenital anomalies such as septal defects, patent ductus arteriosus, transposition of the great arteries, and tetralogy of Fallot will be identified. Valvular lesions and methods for evaluating valvular function will be discussed. MR imaging findings in acquired disorders such as aneurysms and pericardial disease will be described.