The relationship between CT scout landmarks and lung boundaries on chest CT: guidelines for minimizing excess z-axis scan length.

OBJECTIVES: As the relationship between CT scout landmarks and chest CT boundaries is not known, the selected scan length is often greater than necessary for the CT scan, resulting in increased radiation dose to the neck and upper abdomen. The purpose of this study is to establish the relationship between CT scout landmarks with the superior and inferior boundaries of the lungs on chest CT. METHODS: Retrospective comparison of the location of the top of the first rib on frontal scout and the most inferior costophrenic angle on lateral scout to the chest CT slice just above and below the lungs. The percent of scans that would exclude part of the lung based on CT initiated at several distances above or below these landmarks was calculated. RESULTS: There was 2.7 times greater variability between scout landmarks and lung boundaries inferiorly than superiorly on chest CT (p < 0.001). Initiating CT at the top of the first rib on scout did not exclude any lung on CT. Initiating CT 0, 1, 2, 3, and 4 cm inferior to the CPA on lateral scout excluded part of the lung in 45.7%, 12.9%, 4.3%, 1.9%, and 0.8% of CTs. CONCLUSIONS: Chest CT to include the lungs should be performed from the top of the first rib to 3 or 4 cm below the costophrenic angle on lateral topogram. KEY POINTS: • There is a greater motion at the inferior lung than at the superior lung. • Chest CT acquisition from the top of the first rib on scout would not exclude the lung. • Chest CT acquisition from CPA on lateral scout would exclude the lung 46% of time.

Myocardial Amyloid Quantification with Look-Locker Magnetic Resonance Sequence in Cardiac Amyloidosis. Diagnostic Accuracy in Clinical Practice and Histological Validation.

BACKGROUND: Cardiac magnetic resonance (CMR) has demonstrated its utility in the noninvasive diagnosis of cardiac amyloidosis (CA). Our aim was to evaluate the ability of standard Look-Locker sequences to quantify amyloid deposition in CA. METHODS AND RESULTS: Consecutive patients referred for CMR for possible CA were retrospectively evaluated. Positive cardiac biopsy and/or typical pattern of late gadolinium enhancement were required for the diagnosis of CA. Postcontrast T1 values were obtained from Look-Locker sequences and correlated with markers of severity of disease and major events. When cardiac biopsies were available, histological validation was determined. A total of 174 patients were included. A final diagnosis of CA was reached in 37.4%. Myocardial and endocardial T1 times, as well as the respective ratios with blood and skeletal muscle, were lower among patients with CA and demonstrated good diagnostic performance. The best parameters were myocardial/blood (area under the curve 0.83; P < .001) and endocardial/blood (area under the curve 0.84; P < .001) T1 ratios. Among patients with CA, no associations were found between T1 ratios either with markers of amyloid burden or with prognostic variables. However, all T1 indexes showed significant correlations with histological quantification of amyloid deposition. CONCLUSIONS: Look-Looker derived postcontrast T1 shows good diagnostic accuracy to detect CA and correlation with histological amyloid burden.

Correction to: Baseline and annual repeat rounds of screening: implications for optimal regimens of screening.

The original version of this article unfortunately contained a mistake. The conflict of interest was incorrect.

Baseline and annual repeat rounds of screening: implications for optimal regimens of screening.

OBJECTIVES: Differences in results of baseline and subsequent annual repeat rounds provide important information for optimising the regimen of screening. METHODS: A prospective cohort study of 65,374 was reviewed to examine the frequency/percentages of the largest noncalcified nodule (NCN), lung cancer cell types and Kaplan-Meier (K-M) survival rates, separately for baseline and annual rounds. RESULTS: Of 65,374 baseline screenings, NCNs were identified in 28,279 (43.3%); lung cancer in 737 (1.1%). Of 74,482 annual repeat screenings, new NCNs were identified in 4959 (7%); lung cancer in 179 (0.24%). Only adenocarcinoma was diagnosed in subsolid NCNs. Percentages of lung cancers by cell type were significantly different (p < 0.0001) in the baseline round compared with annual rounds, reflecting length bias, as were the ratios, reflecting lead times. Long-term K-M survival rate was 100% for typical carcinoids and for adenocarcinomas manifesting as subsolid NCNs; 85% (95% CI 81-89%) for adenocarcinoma, 74% (95% CI 63-85%) for squamous cell, 48% (95% CI 34-62%) for small cell. The rank ordering by lead time was the same as the rank ordering by survival rates. CONCLUSIONS: The significant differences in the frequency of NCNs and frequency and aggressiveness of diagnosed cancers in baseline and annual repeat need to be recognised for an optimal regimen of screening. KEY POINTS: • Lung cancer aggressiveness varies considerably by cell type and nodule consistency. • Kaplan-Meier survival rates varied by cell type between 100% and 48%. • The percentages of lung cancers by cell type in screening rounds reflect screening biases. • Rank ordering by cell type survival is consistent with that by lead times. • Empirical evidence provides critical information for the regimen of screening.

SHILO, a novel dual imaging approach for simultaneous HI-/LOw temporal (Low-/Hi-spatial) resolution imaging for vascular dynamic contrast enhanced cardiovascular magnetic resonance: numerical simulations and feasibility in the carotid arteries.

BACKGROUND: Dynamic contrast enhanced (DCE) cardiovascular magnetic resonance (CMR) is increasingly used to quantify microvessels and permeability in atherosclerosis. Accurate quantification depends on reliable sampling of both vessel wall (VW) uptake and contrast agent dynamic in the blood plasma (the so called arterial input function, AIF). This poses specific challenges in terms of spatial/temporal resolution and matched dynamic MR signal range, which are suboptimal in current vascular DCE-CMR protocols. In this study we describe a novel dual-imaging approach, which allows acquiring simultaneously AIF and VW images using different spatial/temporal resolution and optimizes imaging parameters for the two compartments. We refer to this new acquisition as SHILO, Simultaneous HI-/LOw-temporal (low-/hi-spatial) resolution DCE-imaging. METHODS: In SHILO, the acquisition of low spatial resolution single-shot AIF images is interleaved with segments of higher spatial resolution images of the VW. This allows sampling the AIF and VW with different spatial/temporal resolution and acquisition parameters, at independent spatial locations. We show the adequacy of this temporal sampling scheme by using numerical simulations. Following, we validate the MR signal of SHILO against a standard 2D spoiled gradient recalled echo (SPGR) acquisition with in vitro and in vivo experiments. Finally, we show feasibility of using SHILO imaging in subjects with carotid atherosclerosis. RESULTS: Our simulations confirmed the superiority of the SHILO temporal sampling scheme over conventional strategies that sample AIF and tissue curves at the same time resolution. Both the median relative errors and standard deviation of absolute parameter values were lower for the SHILO than for conventional sampling schemes. We showed equivalency of the SHILO signal and conventional 2D SPGR imaging, using both in vitro phantom experiments (R2 =0.99) and in vivo acquisitions (R2 =0.95). Finally, we showed feasibility of using the newly developed SHILO sequence to acquire DCE-CMR data in subjects with carotid atherosclerosis to calculate plaque perfusion indices. CONCLUSIONS: We successfully demonstrate the feasibility of using the newly developed SHILO dual-imaging technique for simultaneous AIF and VW imaging in DCE-CMR of atherosclerosis. Our initial results are promising and warrant further investigation of this technique in wider studies measuring kinetic parameters of plaque neovascularization with validation against gold standard techniques.

Clinical demand for chest/abdomen/pelvis anatomy following thoracic or lumbar spine CT.

The purpose of this study is to determine how often CT is repeated to obtain chest/abdomen/pelvis data outside the reconstructed field of view (FOV) on a prior spine CT. Radiology records of 1,239 consecutive thoracic and lumbar spine CT exams of 1,025 patients from January 1, 2006 to December 31, 2008 were retrospectively reviewed to identify patients who subsequently had CT studies of the chest, abdomen, and/or pelvis. The CT data were also evaluated for contrast enhancement, slice thickness, radiation dose, and reason for subsequent CT exam. Over 3 years, 290 of the 1,239 (24%) spine CT exams were followed by CT of the same anatomic region to evaluate extraspinal anatomy. The use or nonuse of contrast in these follow-up studies was the same as the preceding spine study in 91 cases, which were repeated on the same day (n = 37), within 7 days (n = 19), within 8-30 days (n = 15), or after 30 days (n = 20). Fourteen of 25 (56%) T spine CTs and 34 of 52 (65%) L spine CTs without contrast were followed by a chest CT or abdomen/pelvis CT without contrast within 7 days, respectively. Among 31 pediatric exams, 6 of 31 (19%) spine CTs were followed by a CT of the same anatomic region, all within 7 days. Reconstructing full FOV images of spine CT scans in addition to the standard coned down spine FOV may reduce redundant CT imaging and radiation dose.

Epicardial adipose tissue is associated with left atrial volume and fibrosis in patients with atrial fibrillation.

Background: Obesity is a risk factor for atrial fibrillation (AF) and strongly influences the response to treatment. Atrial fibrosis shows similar associations. Epicardial adipose tissue (EAT) may be a link between these associations. We sought to assess whether EAT is associated with body mass index (BMI), left atrial (LA) fibrosis and volume. Methods: LA fibrosis and EAT were assessed using late gadolinium enhancement, and Dixon MRI sequences, respectively. We derived 3D models incorporating fibrosis and EAT, then measured the distance of fibrotic and non-fibrotic areas to the nearest EAT to assess spatial colocalization. Results: One hundred and three AF patients (64% paroxysmal, 27% female) were analyzed. LA volume index was 54.9 (41.2, 69.7) mL/m2, LA EAT index was 17.4 (12.7, 22.9) mL/m2, and LA fibrosis was 17.1 (12.4, 23.1)%. LA EAT was significantly correlated with BMI (R = 0.557, p < 0.001); as well as with LA volume and LA fibrosis after BSA adjustment (R = 0.579 and R = 0.432, respectively, p < 0.001 for both). Multivariable analysis showed LA EAT to be independently associated with LA volume and fibrosis. 3D registration of fat and fibrosis around the LA showed no clear spatial overlap between EAT and fibrotic LA regions. Conclusion: LA EAT is associated with obesity (BMI) as well as LA volume and fibrosis. Regions of LA EAT did not colocalize with fibrotic areas, suggesting a systemic or paracrine mechanism rather than EAT infiltration of fibrotic areas.

Ordinal scoring of coronary artery calcifications on low-dose CT scans of the chest is predictive of death from cardiovascular disease.

PURPOSE: To assess the usefulness of ordinal scoring of the visual assessment of coronary artery calcification (CAC) on low-dose computed tomographic (CT) scans of the chest in the prediction of cardiovascular death. MATERIALS AND METHODS: All participants consented to low-dose CT screening according to an institutional review board-approved protocol. The amount of CAC was assessed on ungated low-dose CT scans of the chest obtained between June 2000 and December 2005 in a cohort of 8782 smokers aged 40-85 years. The four main coronary arteries were visually scored, and each participant received a CAC score of 0-12. The date and cause of death was obtained by using the National Death Index. Follow-up time (median, 72.3 months; range, 0.3-91.9 months) was calculated as the time between CT and death, loss to follow-up, or December 31, 2007, whichever came first. Logistic regression analysis was used to determine the risk of mortality according to CAC category adjusted for age, pack-years of cigarette smoking, and sex. The same analysis to determine the hazard ratio for survival from cardiac death was performed by using Cox regression analysis. RESULTS: The rate of cardiovascular deaths increased with an increasing CAC score and was 1.2% (43 of 3573 subjects) for a score of 0, 1.8% (66 of 3569 subjects) for a score of 1-3, 5.0% (51 of 1015 subjects) for a score of 4-6, and 5.3% (33 of 625 subjects) for a score of 7-12. With use of subjects with a CAC score of 0 as the reference group, a CAC score of at least 4 was a significant predictor of cardiovascular death (odds ratio [OR], 4.7; 95% confidence interval: 3.3, 6.8; P < .0001); when adjusted for sex, age, and pack-years of smoking, the CAC score remained significant (OR, 2.1; 95% confidence interval: 1.4, 3.1; P = .0002). CONCLUSION: Visual assessment of CAC on low-dose CT scans provides clinically relevant quantitative information as to cardiovascular death.

Effect of blood flow on double inversion recovery vessel wall MRI of the peripheral arteries: quantitation with T2 mapping and comparison with flow-insensitive T2-prepared inversion recovery imaging.

Blood suppression in the lower extremities using flow-reliant methods such as double inversion recovery may be problematic due to slow blood flow. T(2) mapping using fast spin echo (FSE) acquisition was utilized to quantitate the effectiveness of double inversion recovery blood suppression in 13 subjects and showed that 25 +/- 12% of perceived vessel wall pixels in the popliteal arteries contained artifactual blood signal. To overcome this problem, a flow-insensitive T(2)-prepared inversion recovery sequence was implemented and optimal timing parameters were calculated for FSE acquisition. Black blood vessel wall imaging of the popliteal and femoral arteries was performed using two-dimensional T(2)-prepared inversion recovery-FSE in the same 13 subjects. Comparison with two-dimensional double inversion recovery-FSE showed that T(2)-prepared inversion recovery-FSE reduced wall-mimicking blood artifacts that inflated double inversion recovery-FSE vessel wall area measurements in the popliteal artery.

Rapid and accurate left ventricular chamber quantification using a novel CMR segmentation algorithm: a clinical validation study.

PURPOSE: To evaluate the clinical performance of a novel automated left ventricle (LV) segmentation algorithm (LV-METRIC) that involves no geometric assumptions. MATERIALS AND METHODS: LV-METRIC and manual tracing (MT) were used independently to quantify LV volumes and LVEF (ejection fraction) for 151 consecutive patients who underwent cine-CMR (steady-state free precession). Phase contrast imaging was used to independently measure stroke volume. RESULTS: LV-METRIC was successful in all cases. Mean LVEF was within 1 point of MT (Delta 0.6 +/- 2.3%, P < 0.05), with smaller differences among patients with (0.5 +/- 2.5%) versus those without (0.9 +/- 2.3%; P = 0.01) advanced systolic dysfunction (LVEF

Storm and STEMI: a case report of unexpected cardiac complications of thyrotoxicosis.

BACKGROUND: Thyroid storm is a rare condition with well-known cardiovascular manifestations including tachycardia, atrial fibrillation, heart failure, and myocardial infarction (MI). Several uncommon conditions that can mimic MI are associated with thyrotoxicosis and discussed in this case. CASE SUMMARY: A 23-year-old previously healthy male presented after the onset of generalized weakness and inability to rise from bed in the setting of 35 kg of unintentional weight loss, and was found to have profound hypokalaemia, elevated thyroid hormone, and suppressed thyroid-stimulating hormone consistent with thyrotoxicosis secondary to Grave's disease. Following hospital admission, he developed worsening tachycardia with dynamic anteroseptal ST-segment elevations and elevated cardiac biomarkers concerning for MI. He was treated with aspirin, ticagrelor, and a heparin infusion, but was unable to tolerate beta-blockade acutely due to hypotension. Echocardiography demonstrated a severely dilated left ventricle (left ventricular end-diastolic volume index 114 mL/m2) and severely reduced systolic function (ejection fraction 23%) with global hypokinesis. Following initiation of propylthiouracil, iodine solution, and stress-dosed steroids his tachycardia and ST-elevations resolved. Computed tomography (CT) coronary angiography demonstrated no evidence of coronary stenosis. He was discharged on methimazole, metoprolol, and lisinopril and found to have recovered left ventricular systolic function at 2-month follow-up. DISCUSSION: Thyrotoxicosis can rarely cause coronary vasospasm, stress cardiomyopathy, and autoimmune myocarditis. These conditions should be suspected in hyperthyroid patients with features of MI and normal coronary arteries. Workup should include laboratory evaluation, electrocardiography (ECG), echocardiography, and non-invasive or invasive ischaemic evaluation.

Retrospective analysis of 1118 outpatient chest CT scans to determine factors associated with excess scan length.

RATIONALE OBJECTIVES: Excess z-axis scanning continues as an unnecessary source of radiation. This study seeks to determine patient, technologist and CT factors that affect excess scan length for chest CT. MATERIALS AND METHODS: Retrospective evaluation of 1118 consecutive noncontrast chest CT scans, over twelve consecutive months, was performed for evaluation of scan length above and below the lung parenchyma. Scan length >2 cm was considered excessive. Bivariate analysis for mean excess scan length and presence of excess scan length analyzed technologist's exam volume during the study period, patient age, patient gender, day of week, and time of day as categorical variables. Technologists performing >100 chest CT scans during the study period were considered high-volume while all others were considered low-volume. RESULTS: Mean excess scan length was 5 mm, 29 mm, and 33 mm above the lungs, below the lungs, and total. 81% and 95% of studies had excess scanning above the lungs and below the lungs respectively. Multivariable analysis showed that high volume technologists, male patients, and patients younger than 65 had a greater amount of excess scan length and presence of excessive scanning above the lungs; high volume technologists and male patients had a greater amount of excess scan length below the lungs, and high volume technologists and patients older than 65 had greater presence of excessive scanning below the lungs, each p < 0.001. CONCLUSIONS: Excess scanning on chest CT is common, varies by patient age and gender and was significantly greater for high volume technologists.

Tumor response in patients with advanced non-small cell lung cancer: perfusion CT evaluation of chemotherapy and radiation therapy.

OBJECTIVE: The objectives of this study were to prospectively evaluate changes in tumor perfusion after chemoradiation therapy and to investigate the feasibility of perfusion CT for prediction of early tumor response and prognosis of non-small cell lung cancer. SUBJECTS AND METHODS: Perfusion CT was performed on an MDCT scanner with 50 mL of iodinated contrast material injected at 4 mL/s. The quality of each functional map was rated from 0 to 3 for 123 patients with confirmed lung cancer. A subset of images was independently reviewed by two radiologists to measure interobserver and intraobserver variability. Perfusion parameters and tumor response were assessed for 35 patients with non-small cell lung cancer who underwent chemoradiation therapy. Progression-free survival and overall survival were analyzed for 22 patients who underwent repeated perfusion CT after therapy. RESULTS: Image quality was graded 2 (moderate) or 3 (good) in 68.2% of cases. High interobserver and intraobserver correlations of perfusion parameters were found on qualified images. The patients who responded to chemoradiation therapy had significantly greater blood flow (p = 0.023) than patients who did not respond. The median progression-free survival period of the patients with an increased permeability-surface area product was 4.7 months, significantly lower than the median progression-free survival period of 19.0 months among patients with a decreased permeability-surface area product (p < 0.001). The median overall survival period was 10.6 months for the group with an increased permeability-surface area product, significantly lower than the 19.3 months for the group with a decreased permeability-surface area product (p = 0.004). CONCLUSION: Non-small cell lung cancer with higher perfusion is more sensitive to chemoradiation therapy than that with lower perfusion. After chemoradiation therapy, findings at perfusion CT are a significant predictor of early tumor response and overall survival among patients with non-small cell lung cancer.

Left ventricle: automated segmentation by using myocardial effusion threshold reduction and intravoxel computation at MR imaging.

UNLABELLED: This retrospective analysis of existing patient data had institutional review board approval and was performed in compliance with HIPAA. No informed consent was required. The purpose of the study was to develop and validate an algorithm for automated segmentation of the left ventricular (LV) cavity that accounts for papillary and/or trabecular muscles and partial voxels in cine magnetic resonance (MR) images, an algorithm called LV Myocardial Effusion Threshold Reduction with Intravoxel Computation (LV-METRIC). The algorithm was validated in biologic phantoms, and its results were compared with those of manual tracing, as well as those of a commercial automated segmentation software (MASS [MR Analytical Software System]), in 38 subjects. LV-METRIC accuracy in vitro was 98.7%. Among the 38 subjects studied, LV-METRIC and MASS ejection fraction estimations were highly correlated with manual tracing (R(2) = 0.97 and R(2) = 0.95, respectively). Ventricular volume estimations were smaller with LV-METRIC and larger with MASS than those calculated by using manual tracing, though all results were well correlated (R(2) = 0.99). LV-METRIC volume measurements without partial voxel interpolation were statistically equivalent to manual tracing results (P > .05). LV-METRIC had reduced intraobserver and interobserver variability compared with other methods. MASS required additional manual intervention in 58% of cases, whereas LV-METRIC required no additional corrections. LV-METRIC reliably and reproducibly measured LV volumes. SUPPLEMENTAL MATERIAL: http://radiology.rsnajnls.org/cgi/content/full/248/3/1004/DC1.

Effects of papillary muscles and trabeculae on left ventricular quantification: increased impact of methodological variability in patients with left ventricular hypertrophy.

BACKGROUND: Accurate quantification of left ventricular mass and ejection fraction is important for patients with left ventricular hypertrophy. Although cardiac magnetic resonance imaging has been proposed as a standard for these indices, prior studies have variably included papillary muscles and trabeculae in myocardial volume. This study investigated the contribution of papillary muscles and trabeculae to left ventricular quantification in relation to the presence and pattern of hypertrophy. METHODS: Cardiac magnetic resonance quantification was performed on patients with concentric or eccentric hypertrophy and normal controls (20 per group) using two established methods that included papillary muscles and trabeculae in myocardium (method 1) or intracavitary (method 2) volumes. RESULTS: Among all patients, papillary muscles and trabeculae accounted for 10.5% of ventricular mass, with greater contribution with left ventricular hypertrophy than normals (12.6 vs. 6.2%, P < 0.001). Papillary muscles and trabeculae mass correlated with ventricular wall mass (r = 0.53) and end-diastolic volume (r = 0.52; P < 0.001). Papillary muscles and trabeculae inclusion in myocardium (method 1) yielded smaller differences with a standard of mass quantification from linear ventricular measurements than did method 2 (P < 0.001). Method 1 in comparison with method 2 yielded differences in left ventricular mass, ejection fraction and volume in all groups, especially in patients with hypertrophy: the difference in ventricular mass index was three-fold to six-fold greater in hypertrophy than normal groups (P < 0.001). Difference in ejection fraction, greatest in concentric hypertrophy (P < 0.001), was independently related to papillary muscles and trabeculae mass, ventricular wall mass, and smaller ventricular volume (R = 0.56, P < 0.001). CONCLUSION: Established cardiac magnetic resonance methods yield differences in left ventricular quantification due to variable exclusion of papillary muscles and trabeculae from myocardium. The relative impact of papillary muscles and trabeculae exclusion on calculated mass and ejection fraction is increased among patients with hypertrophy-associated left ventricular remodeling.

3-T navigator parallel-imaging coronary MR angiography: targeted-volume versus whole-heart acquisition.

OBJECTIVE: The purpose of this study was to compare whole-heart acquisition with targeted-volume acquisition in 3-T navigator coronary MR angiography with parallel imaging. SUBJECTS AND METHODS: The right and left coronary arteries of 20 subjects were imaged with axial whole-heart acquisition and two oblique targeted-volume acquisitions. RESULTS: Both whole-heart and targeted-volume acquisitions were completed with similar navigator efficiencies ( approximately 50%) and depicted similar coronary artery diameters ( approximately 3 mm) (p >or= 0.06). The lengths of the coronary arteries were not significantly different (p = 0.07-0.45) for the whole-heart and targeted-volume approaches. Depiction of the sharper coronary arteries (p

The Added Value of Computer-aided Detection of Small Pulmonary Nodules and Missed Lung Cancers.

Lung cancer at its earliest stage is typically manifested on computed tomography as a pulmonary nodule, which could be detected by low-dose multidetector computed tomography technology and the use of thinner collimation. Within the last 2 decades, computer-aided detection (CAD) of pulmonary nodules has been developed to meet the increasing demand for lung cancer screening computed tomography with a larger set of images per scan. This review introduced the basic techniques and then summarized the up-to-date applications of CAD systems in clinical and research programs and in the low-dose lung cancer screening trials, especially in the detection of small pulmonary nodules and missed lung cancers. Many studies have already shown that the CAD systems could increase the sensitivity and reduce the false-positive rate in the diagnosis of pulmonary nodules, especially for the small and isolated nodules. Further improvements to the current CAD schemes are needed to detect nodules accurately, particularly for subsolid nodules.

Congenital Coronary Artery Anomalies and Implications.

This pictorial essay presents cases of congenital coronary artery anomalies, including congenital anomalies of origin, course, and termination. Familiarity with atypical coronary anatomy and clinical presentation may facilitate appropriate diagnosis and management, particularly as cardiac and thoracic computed tomographic utilization increases.

Aorto-left atrial fistula diagnosed with computed tomographic angiography: A case report.

Aorto-atrial fistulas are a rare diagnosis with limited reports in the clinical literature. These findings are often characterized by echocardiography alone; however, the advent and increased availability and use of CT angiography to diagnose cardiac abnormalities provides improved anatomic visibility of potential defects. We are reporting a case of a 76-year-old male with decompensated heart failure secondary to a fistula between the aorta and left atrium after remote history of bioprosthetic aortic valve replacement.