Short-axis Measurements Research Articles

Accuracy of Non-Electrocardiographically Gated Thoracic CT Angiography for Right Atrial and Right Ventricular Enlargement.

To assess the role of long-axis (LA) and short-axis (SA) measurements of the right atrium (RA) and right ventricle (RV) at non-electrocardiographically (ECG) gated thoracic CT angiography for identification of RA enlargement and RV enlargement. This study was a retrospective case review of 138 patients who underwent both non-ECG-gated CT angiography and ECG-gated CT angiography concurrently from November 2016 through November 2018. The SA and LA of the RA and RV were measured by two observers blinded to the ECG-gated CT angiography data. ECG-gated CT angiography-derived RA end-systolic and RV end-diastolic volumes were used as standard of reference to derive cutoff values for diagnosis of RA and RV enlargement. In this study, 138 patients were evaluated (70 men, 68 women; mean age, 70.0 years ± 18.4 [standard deviation]; mean body mass index, 29.3 kg/m2 ± 8.1). Of these patients, ECG-gated CT angiography revealed 36.2% had RA enhancement and 19.0% had RV enhancement. The best predictor of RA enhancement was the product of atrial LA and SA measurements, for which a threshold value of 3210 mm2 yielded a 94% sensitivity and 81.8% specificity (area under the curve [AUC], 0.92). A threshold of 55.5 mm for LA diameter had 86% sensitivity and 78.4% specificity in identifying RA enlargement. RV enlargement could be predicted if the SA diameter was greater than 48.5 mm (76.9% sensitivity and 64.9% specificity) and with a body surface area indexed value of 27.0 mm/m2 (92.3% sensitivity and 74.8% specificity [AUC, 0.87]). RA and RV enlargement can be accurately diagnosed by using non-ECG-gated CT angiography.© RSNA, 2019Supplemental material is available for this article.

Normal pulmonary artery and branch pulmonary artery sizes in children.

To establish standards for pulmonary artery and branch pulmonary artery (PA and BPA) effective diameter (ED) and cross-sectional area (CSA) by using computed tomography (CT) data in children of a wide range of sizes and investigate the roundness of arteries. The ED (average of short and long axes) and CSA for the PA and BPA were measured using 1-mm collimation double-oblique reconstructions. Ordinary least squares regression was used to investigate models with various functional forms that related ED and CSA to patient size. Aspect ratio (AR), the short axis divided by long axis, was measured to evaluate roundness. The ideal diameter derived from CSA measurements was compared to ED, short axis, and long axis measurements. 108 CT examinations were analyzed in children without reason for abnormal PA size who ranged in age from 0 to 18years (mean, 10.9years; SD, 5.9years). Interrater reliability was excellent. Data were modeled using a natural log-transformed response variable and a linear term for height as the independent variable. AR for the PA, right pulmonary artery, and left pulmonary artery measured < 0.9 for 38, 55, and 37%, respectively, indicating that many arteries are not round. Ideal diameter was not significantly different than ED but was for short- and long-axis diameter measurements. Normal ED and CSA for PA and BPA were determined for children of different sizes. Measurements outside of the normal range are consistent with dilatation or stenosis. Single diameter techniques are likely to introduce error.

Biplane versus short-axis measures of the left atrium and ventricle in patients with systolic dysfunction assessed by magnetic resonance

PurposeThis study aims to investigate if the time saving biplane method can be an alternative to short-axis measurements for left atrium (LA) and left ventricle (LV) in cardiac magnetic resonance of patients with extensive LV remodeling. Materials and methodsIn 45 patients with coronary artery disease and systolic LV dysfunction [ejection fraction (EF)<50%], LA and LV end-diastolic volume, end-systolic volume, stroke volume, and EF were measured by the biplane area length and by the short-axis volume method. ResultsNo statistical differences between the biplane area length and short-axis volume were found for the LA end-systolic or the LV end-diastolic volumes. However, the biplane area length method overestimated LA stroke volume by 7.1±12.3 ml, LA EF by 6.7±8.8% (both P<.001), LV stroke volume by 6.2±12.9 ml (P=.002), and LV EF by 2.6±4.6% (P<.001). The differences in LV measurements were more evident in patients with severely distorted LV. For LA volume parameters, overall consistency between biplane area length and short-axis approach was good [all intraclass correlation coefficient (ICC)≥0.74] and for LV volume parameters, overall consistency between both approaches was excellent (all ICC≥0.93). ConclusionIn patients with LV systolic dysfunction, the short-axis volume is superior to the biplane method and should be the first choice, when accurate determination of LA and LV EF is the main clinical indication for cardiac magnetic resonance.

Importance of Delphian Lymph Node Evaluation in Autoimmune Thyroiditis: Fact or Fiction?

SummaryBackgroundOur main objective was to evaluate the association between autoimmune thyroiditis and the Delphian lymph node during different stages of thyroiditis.Material/MethodsThe relationships between the ultrasonography (US) results of thyroiditis and characteristics of the Delphian lymph node in different stages of AT were evaluated. Thyroid hormone and antibody levels were assessed. A total of 126 patients were divided into four groups according to the thyroid US findings: Group 1: control cases; Group 2: indeterminate cases; Group 3: established thyroiditis cases; Group 4: advanced-late stage thyroiditis cases.Indeterminate cases attended a 1-year follow-up, and the cases with a sonographic finding matching thyroiditis formed Group 2.ResultsThe rate of Delphian lymph node presence in Group 4 was significantly higher than in Groups 1 and 2 (p<0.01). In addition, its presence was significantly higher in Group 3 than in Group 1 (p<0.05). Although there was a difference in Delphian lymph node presence between Groups 2 and 3, it was not significant (p=0.052), nor was there a significant difference between Groups 1 and 2 (p>0.05). Both the long and short axis measurements were significantly higher in Groups 2, 3, and 4 compared to those in the control group. However, the same increase was not observed in the long/short axis ratio.ConclusionsBoth the presence and dimensions of the Delphian lymph node were highly correlated with the progress of autoimmune thyroiditis. Evaluating the Delphian lymph nodes might prevent missing a diagnosis of autoimmune thyroiditis.

Three-Dimensional Printing of Intracardiac Defects from Three-Dimensional Echocardiographic Images: Feasibility and Relative Accuracy

With the advent of three-dimensional (3D) printers and high-resolution cardiac imaging, rapid prototype constructions of congenital cardiac defects are now possible. Typically, source images for these models derive from higher resolution, cross-sectional cardiac imaging, such as cardiac magnetic resonance imaging or computed tomography. These imaging methods may involve intravenous contrast, sedation, and ionizing radiation. New echocardiographic transducers and advanced software and hardware have optimized 3D echocardiographic images for this purpose. Thus, the objectives of this study were to confirm the feasibility of creating cardiac models from 3D echocardiographic data and to assess accuracy by comparing 3D model measurements with conventional two-dimensional (2D) echocardiographic measurements of cardiac defects. Nine patients undergoing 3D echocardiography were identified (eight with ventricular septal defects, one with three periprosthetic aortic valve leaks). Raw echocardiographic image data were exported anonymously and converted to Digital Imaging and Communications in Medicine format. The image data were filtered for noise reduction, imported into segmentation software to create a 3D digital model, and printed. Measurements of the defects from the 3D model were compared with defect measurements from conventional 2D echocardiographic data. Meticulous care was taken to ensure identical measurement planes. Long- and short-axis measurements of eight ventricular septal defects and three perivalvar leaks were obtained. Mean ± SD values for the 3D model measurements and conventional 2D echocardiographic measurements were 7.5 ± 6.3 and 7.1 ± 6.2 mm respectively (P = .20), indicating no significant differences between the standard 2D and 3D model measurements. The two groups were highly correlated, with a Pearson correlation coefficient of 0.988. The mean absolute error (2D - 3D) for each measurement was 0.4 ± 0.9 mm, indicating accuracy of the 3D model of <1 mm. Three-dimensional printed models of echocardiographic data are technically feasible and may accurately reflect ventricular septal defect anatomy. Three-dimensional models derived from 3D echocardiographic data sets represent a new tool in procedural planning for children with congenital heart disease.

Abstract 19638: Short-Axis Echocardiographic Imaging of the Ascending Aorta is More Accurate than Long-Axis Imaging when Compared to Cardiac Magnetic Resonance Imaging and Computed Tomography

Introduction: Parasternal long-axis echo imaging often underestimates aortic dimensions when compared to CT or MRI. More accurate and reproducible echo methods for determining aortic size would benefit care and reduce cost. We compared novel short-axis aortic echo images to standard long-axis and CT or MRI measurements. Methods: We retrospectively reviewed all cardiac CT/MRI performed in the setting of aortic dilation at Arkansas Children’s Hospital from September 2002 to September 2013. All CT/MRI exams with echocardiograms performed within 3 months were included. One blinded observer reviewed all CT/MRI studies, and measured lateral and anteroposterior dimensions of the aortic sinus (AoS), sinotubular junction (STJ), and ascending aorta (AsAo). Echo measurements were made by 3 independent, blinded observers, and included AoS, STJ, and AsAo in standard long-axis views, as well as novel short-axis measurements: anteroposterior sinus length; maximal left to non-coronary sinus length; and lengths from center right to left coronary sinus or non-coronary sinus. Short-axis anteroposterior and lateral measurements were made of the AsAo at the level of the right pulmonary artery from a high left-parasternal view. All echo measurements were compared to CT/MRI. Pearson product-moment correlation based on Fisher’s transformation was determined for each measure compared to CT/MRI. Results: Fifty MRIs, 17 CTs, and 62 echocardiograms were identified and reviewed. Adequate imaging for long-axis aortic assessment was present in 48/62 (77%) echocardiograms, and 42/62 (68%) had adequate short-axis images. Fifty-three subjects median age 34.7 years met inclusion criteria. Long-axis measurements correlated well with CT/MRI for AoS (r=0.811), but poorly for AsAo (r=0.094). Short-axis measurements correlated equally well with CT/MRI for AoS (r=0.832), and AsAo (r=0.790). Conclusions: Parasternal short-axis echo measurements of the aorta are more accurate than conventional parasternal long-axis measurements when compared to CT/MRI. This simple and reproducible technique should be used routinely for echocardiographic evaluation of the aorta.

Irreversible Electroporation of the Pig Kidney with Involvement of the Renal Pelvis: Technical Aspects, Clinical Outcome, and Three-dimensional CT Rendering for Assessment of the Treatment Zone

To analyze irreversible electroporation (IRE) of the pig kidney with involvement of the renal pelvis. IRE of renal tissue including the pelvis was performed in 10 kidneys in five pigs. Three study groups were defined: group I (two applicators with parallel configuration; n = 11), group II (three applicators with triangular configuration; n = 2), and group III (six applicators with complex configuration; n = 3). After IRE and before euthanasia, pigs underwent contrast-enhanced computed tomography (CT). Technical aspects (radial distance of applicators, resulting mean current), clinical outcome (complications, blood samples), and three-dimensional CT rendering for assessment of the treatment zone (short axis, circularity) were assessed. Radial distances of applicators were 14.3 mm ± 2.8 in group I, 12.3 mm ± 1.9 in group II, and 16.4 mm ± 3.5 in group III. Resulting mean currents were 25.7 A ± 6.5 in group I, 27.0 A ± 7.1 in group II, and 39.4 A ± 8.9 in group III. In group III, two perirenal hematomas were identified. There was no damage to the renal pelvis. During IRE, clinical blood parameters and cardiovascular markers did not change significantly. Short axis measurements were 20.6 mm ± 3.6 in group I, 31.9 mm ± 8.2 in group II, and 39.3 mm ± 2.4 in group III (P < .01 between groups). Circularity scores were 0.8 ± 0.2 in group I, 0.7 ± 0.1 in group II, and 0.7 ± 0.1 in group III, with a score of 1 indicating perfect roundness (P value not significant). IRE of the pig kidney with involvement of the renal pelvis is feasible and safe. Size but not shape of the treatment zone is significantly affected by applicator configuration.

Integration Of CT-Based Measurements Into PET Assessment Significantly Improves The Positive Predictive Value Of Surveillance FDG PET/CT In Patients With Diffuse Large B Cell Lymphoma

IntroductionSurveillance FDG PET, commonly employed in patients with diffuse large B cell lymphoma (DLBCL) who achieve remission following induction, is very sensitive but not sufficiently specific, and is associated with a high false positive (FP) rate. The current study was aimed to investigate whether the employment of specific CT morphologic measurements could reduce FP incidence and improve the positive predictive value (PPV) and clinical applicability of surveillance FDG PET/CT in detecting DLBCL relapse. MethodsThe study was approved by the Institutional Review Board (IRB) of the Rambam Health Care Campus (Haifa, Israel). The study population included patients with DLBCL who participated in the previous surveillance PET study (n=119) (Avivi I, Am J Hematol, 2013), and had at least one positive PET scan, suggestive of disease relapse (n=83). A PET scan was defined as positive in the presence of increased FDG uptake unrelated to physiological bio-distribution of the tracer or to a known benign process. CT-derived features of PET positive sites, including long and short diameters (mm), the presence of calcification and fatty hilum within lymph nodes, were assessed. Patient's outcome, focusing on relapse development, confirmed either by tissue biopsy or by consecutive imaging demonstrating progression in the presence of compatible clinical symptoms, was recorded. The performance of surveillance PET scans, with and without concurrent employment of CT-derived measurements, was compared, focusing on FP rate and PPV of these two approaches to relapse detection. ResultsEighty three follow-up PETs (FU-PETs) interpreted as positive for relapse, were reviewed. Seventy studies performed in 51 patients were included in final analysis, 13 studies were excluded as CT quality did not allow adequate morphologic evaluation. Twenty five of 70 FU-PET studies (36%) were true positive (TP) and 45 (64%) false positive, which is compatible with a PPV of 36%. Evaluation of CT-related parameters of PET positive sites showed that the employment of either long axis ≥15 mm or short axis ≥10 mm, significantly improved the prediction of relapse by PET (Table 1). The ratio between long and short axis measurements was not found to efficiently discriminate between FP and TP scans. Likewise, the presence of calcification or fatty hilum did not affect this discrimination. Multivariate analysis found IPI ≥2, lack of prior rituximab therapy and long or short axis measurements ≥15 and 10 mm, respectively, to be independent predictors of true positivity of FU-PET scans (odds ratio=9.84 ,8.5, and 7.67, P< 0.05, respectively). ConclusionsComplementary application of long and short axis measurements ≥15 and 10 mm, respectively may allow the beneficial use of PET/CT in detection of DLBCL relapse, significantly improving the PPV of this follow-up modality. Disclosures:No relevant conflicts of interest to declare.

Intra- and Interobserver Variability in CT Measurements in Oncology

To assess variability of computed tomographic (CT) measurements of lesions of various sizes and margin sharpness in several organs taken by readers with different levels of experience, as would be found in routine clinical practice. In this institutional review board-approved, HIPAA-compliant retrospective study, 17 radiologists with varying levels of experience independently obtained bidimensional orthogonal axial measurements of 80 lymph nodes, 120 pulmonary lesions, and 120 hepatic lesions, categorized by size and margin sharpness. Repeat measurements were performed 2 or more weeks later. Intraclass correlation coefficients and Bland-Altman plots were used to assess intra- and interobserver variability. For long- and short-axis measurements, respectively, overall intraobserver agreement rates were 0.957 (95% confidence interval [CI]: 0.947, 0.966) and 0.945 (95% CI: 0.933, 0.955); interobserver agreement rates were 0.954 (95% CI: 0.943, 0.963) and 0.941 (95% CI: 0.929, 0.951). Both intra- and interobserver agreement differed by lesion size, margin sharpness, location, and reader experience. Agreement ranged from 0.847 to 0.886 for lesions 20 mm or larger versus 0.745-0.785 for lesions smaller than 10 mm, 0.961 to 0.975 for smooth margins versus 0.924-0.942 for irregular margins, 0.955 to 0.97 for lung lesions versus 0.884-0.94 for lymph nodes, and 0.95 to 0.97 for attending radiologists versus 0.928-0.945 for fellows. Measurement variability decreased with increasing lesion size; 95% limits of agreement for short-axis measurements were -11.6% to 6.7% for lesions smaller than 10 mm versus -6.2% to 4.7% for lesions 20 mm or larger. Overall intra- and interobserver variability rates were similar; in clinical practice, serial CT measurements can be safely performed by different radiologists. Smooth margins, larger lesion size, and greater reader experience resulted in a higher consistency of measurements. Depending on lesion size, increases of 4%-6% or greater in long axis and 5%-7% or greater in short axis and decreases of -6% to -10% or greater in long axis and -6% to -12% or greater in short axis at CT can be considered true changes rather than measurement variation, with 95% confidence.

Intra- and Interobserver Variability in CT Measurements in Oncology

To assess variability of computed tomographic (CT) measurements of lesions of various sizes and margin sharpness in several organs taken by readers with different levels of experience, as would be found in routine clinical practice. In this institutional review board-approved, HIPAA-compliant retrospective study, 17 radiologists with varying levels of experience independently obtained bidimensional orthogonal axial measurements of 80 lymph nodes, 120 pulmonary lesions, and 120 hepatic lesions, categorized by size and margin sharpness. Repeat measurements were performed 2 or more weeks later. Intraclass correlation coefficients and Bland-Altman plots were used to assess intra- and interobserver variability. For long- and short-axis measurements, respectively, overall intraobserver agreement rates were 0.957 (95% confidence interval [CI]: 0.947, 0.966) and 0.945 (95% CI: 0.933, 0.955); interobserver agreement rates were 0.954 (95% CI: 0.943, 0.963) and 0.941 (95% CI: 0.929, 0.951). Both intra- and interobserver agreement differed by lesion size, margin sharpness, location, and reader experience. Agreement ranged from 0.847 to 0.886 for lesions 20 mm or larger versus 0.745-0.785 for lesions smaller than 10 mm, 0.961 to 0.975 for smooth margins versus 0.924-0.942 for irregular margins, 0.955 to 0.97 for lung lesions versus 0.884-0.94 for lymph nodes, and 0.95 to 0.97 for attending radiologists versus 0.928-0.945 for fellows. Measurement variability decreased with increasing lesion size; 95% limits of agreement for short-axis measurements were -11.6% to 6.7% for lesions smaller than 10 mm versus -6.2% to 4.7% for lesions 20 mm or larger. Overall intra- and interobserver variability rates were similar; in clinical practice, serial CT measurements can be safely performed by different radiologists. Smooth margins, larger lesion size, and greater reader experience resulted in a higher consistency of measurements. Depending on lesion size, increases of 4%-6% or greater in long axis and 5%-7% or greater in short axis and decreases of -6% to -10% or greater in long axis and -6% to -12% or greater in short axis at CT can be considered true changes rather than measurement variation, with 95% confidence.

Optimal wrist position for long and short axis ultrasound guided radial artery cannulation.

The radial artery is the most common site for arterial cannulation. Procedures for improving radial artery cannulation have involved direct visualization of the vessel with ultrasonography (US). The aim of this study evaluate the short axis and long axis radial artery measurements at 0º, 45º, 60º wrist joint angle and find out the optimal wrist joint angle for long and short axis US guided radial artery cannulation. This study was approved by the Institutional Ethical Committee and the study was performed in accordance with the ethical principles for human investigations, as outlined by the Second Declaration of Helsinki. One hundred fifty-two (90 men and 62 women, 18-48 years of age, mean age: 32.9 ± 6.1) healthy volunteers were recruited. The radial artery distance between skin and height, width, area in short axis and radial artery distance between skin and height was measured in long axis at 0º, 45º, 60º wrist joint angle were measured. Results. Short axis radial artery distance between skin, width, height, area and long axis radial artery distance between skin, height were statistically significantly different among 0º, 45º, 60º (p< 0.05; for all comparisons). Short axis width was statistically significantly increased at 45º compared to at 0º (p< 0.001;). Short axis radial artery distance between skin and height at 45º were statistically significantly decreased than at 0º (p< 0.001; for all comparisons) and long axis skin distance and height at 45º were also statistically significantly decreased than at 0º (p< 0.001; for both comparisons). Short axis radial artery skin distance and area at 60º is statistically significantly decreased than at 45º (p< 0.001; for both comparisons) and also long axis height of radial artery at 60º is statistically significantly decreased than at 45º (p< 0.001;). Angle increment up to 45º might help clinicians for radial artery cannulation in short axis plane whereas this angle increment maneuver decreased the arterial height in long axis which might be a potential disadvantage for cannulation.

Skull base CT: normative values for size and symmetry of the facial nerve canal, foramen ovale, pterygoid canal, and foramen rotundum

Contrast-enhanced MRI is the mainstay for detecting pathology in the skull base foramina and nerve canals, through demonstration of abnormal enhancement. When MRI is contraindicated, or unable to differentiate tumor from non-neoplastic pathology, high-resolution skull base CT is indicated to assess for nerve canal or foramen widening, which is currently determined subjectively. The purpose of this study is to provide objective CT criteria that may help distinguish between normal asymmetry and pathologic nerve canal or foramen widening. Temporal bone CTs of 50 consecutive adults without facial or trigeminal nerve pathology were retrospectively reviewed. Short axis measurements were obtained in the axial plane for three segments of the facial nerve canal (labyrinthine, tympanic, and mastoid), foramen ovale, pterygoid canal and foramen rotundum on both sides in each subject. Descriptive statistics were obtained, and left-right asymmetry was calculated. Nerve canal/foramen size was normally distributed across subjects, with a minimal amount of left-right asymmetry. The upper limits of the 95% confidence interval for absolute left-right asymmetry were: 0.25, 0.21, and 0.15mm for the labyrinthine, tympanic, and mastoid segments of the facial nerve canal, respectively; 0.62mm for foramen ovale; 0.36mm for pterygoid canal; 0.38mm for foramen rotundum. Relative asymmetry is more important than absolute size for determining nerve canal/foramen abnormality. These normative data may be useful adjuncts to subjective assessments of nerve canal/foramen size when using skull base CT to identify tumor.

Seasonal phenotypic flexibility of flight muscle size in small birds: a comparison of ultrasonography and tissue mass measurements

Changes in flight muscle size are important mediators of phenotypic flexibility in birds, so the ability to track such changes over time in individual birds is a valuable tool for investigating phenotypic flexibility. Ultrasonography has been used to track changes in flight muscle size in shorebirds, but has not been previously used to track such changes in small birds, despite variation in flight muscle size being an important contributor to phenotypic flexibility in these birds. One prominent avian example of phenotypic flexibility is the seasonal phenotypes of small birds in response to climatic variation. The winter phenotype in these birds is characterized by increases in organismal metabolic rates and pectoralis muscle mass. We measured seasonal flight muscle size in House Sparrows (Passer domesticus, 25–30 g) using both ultrasonography and wet muscle mass and tested the correlation between ultrasonographic measures of breast muscle thickness and muscle mass. We further tested whether ultrasonographic measures of muscle thickness were sufficiently precise to detect seasonal variation in flight muscle mass. Muscle mass was significantly and positively associated with ultrasonographic measurements of breast muscle thickness for short-axis (SA), long-axis (LA), and combined SA and LA measurements. Breast muscle mass was significantly greater in winter than in summer (17.5 %) and muscle thickness also increased significantly in winter for both SA (9.1 %) and LA (7.5 %) measures. Thus, these data confirm that winter elevations of flight muscle mass consistently contribute to the winter phenotype in House Sparrows and that ultrasonography is effective in detecting seasonal changes in muscle mass in small birds.

Ventricular short-axis measurements in patients with pulmonary embolism: Effect of ECG-gating on variability, accuracy, and risk prediction

ObjectiveTo assess prospectively the intra- and interobserver variability, accuracy, and prognostic value of right and left ventricular short-axis diameter (RVd and LVd) measurements for risk stratification in patients with pulmonary embolism (PE) using ECG-gated compared to non-gated CT. Materials and methodsSixty consecutive patients (33 women; mean age 58.7±10.3 years) with suspicion of PE underwent both non-gated and ECG-gated chest CT. RVd and LVd on four-chamber views and intra- and interobserver agreements were calculated for both protocols. RVd/LVd ratios were calculated and were related to 30-days adverse clinical events using receiver operating characteristics with area-under-the-curve (AUC) analyses. ResultsBoth inter- and intraobserver variability showed narrower limits of agreement for all measurements with ECG-gated as compared to non-gated CT. Diameter measurements were significantly lower using non-ECG-gated CT as compared to ECG-gated CT for RVd and LVd (both p<.05). The AUC for the RVd/LVd ratio from ECG-gated CT was significantly larger than that from non-gated CT (0.956, 95% CI: 0.768–0.999 versus 0.675, 95% CI: 0.439–0.860; p=.048). ConclusionRVd and LVd measurements from ECG-gated chest CT show less intra- and interobserver variability and more accurately reflect ventricular function. In our patient cohort ECG-gated chest CT allows better prediction of short-term outcome of patients with acute PE that needs to be validated in a larger outcome study.

Myocardial T1 mapping with MRI: Comparison of look‐locker and MOLLI sequences

To evaluate the relationship between "Look-Locker" (LL) and modified Look-Locker Inversion recovery (MOLLI) approaches for T1 mapping of the myocardium. A total of 168 myocardial T1 maps using MOLLI and 165 maps using LL were obtained in human subjects at 1.5 Tesla. The T1 values of the myocardium were calculated before and at five time points after gadolinium administration. All time and heart rate normalizations were done. The T1 values obtained were compared to determine the absolute and bias agreement. The precontrast global T1 values were similar when measured by the LL and by MOLLI technique (mean, 1004.9 ms ± 120.3 versus 1034.1 ms ± 53.1, respectively, P = 0.26). Postcontrast myocardial T1 time from LL was significantly longer than MOLLI from 5 to 25 min (mean difference, LL - MOLLI was +61.8 ± 46.4 ms, P < 0.001). No significant differences in T1 values were noted between long and short axis measurements for either MOLLI or LL. Postcontrast LL and MOLLI showed very good agreement, although LL values are higher than MOLLI. Precontrast T1 values showed good agreement, however LL has greater limits of agreement. Short and long axis planes can reliably assess T1 values.

In Vitro Blood-perfused Bovine Liver Model: A Physiologic Model for Evaluation of the Performance of Radiofrequency Ablation Devices

Purpose To describe an in vitro blood-perfused bovine liver model for the testing of radiofrequency (RF) ablation devices and compare the performance of a specific RF ablation device in the model relative to three other biologic models. Materials and Methods Fresh bovine livers were used to create three in vitro models: blood-perfused, Krebs–Henseleit (KH) solution–perfused, and nonperfused. The perfused models were connected to a heart–lung machine via the portal vein and perfused with heparinized autologous blood or KH solution under physiologic conditions. Six swine were used as in vivo liver models. A cluster electrode and RF ablation system was operated in impedance mode for 12 minutes in all models. Ablated livers were sectioned, with long- and short-axis measurements of the ablations obtained, and statistical analysis was performed. Results A total of 39, 23, 17, and 12 ablations were performed in 14, 6, 5, and 6 blood-perfused bovine livers, KH solution–perfused bovine livers, nonperfused bovine livers, and in vivo porcine livers, respectively. On cut specimens, the average diameters of ablation zones were 4.00 cm (95% CI, 3.88–4.13) in blood-perfused livers, 4.34 cm (95% CI, 4.14–4.50) in KH solution–perfused livers, 4.67 cm (95% CI, 4.50–4.83) in nonperfused livers, and 3.56 cm (95% CI, 3.26–3.83) in in vivo porcine livers. In all models, the ablation zone diameters were normally distributed. Conclusions In the in vitro blood-perfused bovine liver model, the size of ablations produced by an RF ablation device are closer in size to those seen in porcine liver in vivo compared with the lesions produced in KH solution–perfused or nonperfused bovine liver.

Quantitative Estimates of the Variability of In Vivo Sonographic Measurements of the Mouse Aorta for Studies of Abdominal Aortic Aneurysms and Related Arterial Diseases

Burgeoning interest in reducing the morbidity and mortality associated with abdominal aortic aneurysms (AAAs) has led to experimental strategies to elucidate the disease process and attain pharmacologic regression using the apolipoprotein E(-/-) (ApoE(-/-)) mouse model of angiotensin-induced AAAs and in vivo sonography. However, the variability of in vivo sonographic measurements of the mouse aorta has not been established. Thus, our purpose was to determine quantitative estimates of the variability of in vivo sonographic measurements of the mouse aorta as a guide for the design and assessment of studies focused on regression of AAAs and related arterial diseases. We used Bland-Altman, locally weighted scatterplot-smoothing regression, and resampling (bootstrapping) methods for variability analyses of multiple in vivo short- and long-axis sonographic measurements of ApoE(-/-) mouse aortas. We measured distinct aortic sites in vivo at the baseline and after angiotensin-induced AAAs and ex vivo using digital calipers. We analyzed 236 data points from 10 male mice (14 weeks old; mean weight ± SD, 29.7 ± 1.6 g). Overall intramouse differences between short- and long-axis and in vivo and ex vivo measurements were 0.038 (95% confidence interval [CI], 0.031-0.046) and 0.085 (95% CI, 0.062-0.109) mm, respectively. Intermouse differences in short-axis measurements were 0.047 (95% CI, 0.042-0.053), 0.049 (95% CI, 0.044-0.055), and 0.039 (95% CI, 0.036-0.042) mm for infrarenal, suprarenal, and thoracic measurements, respectively; differences in long-axis measurements were 0.054 (95% CI, 0.044-0.064), 0.029 (95% CI, 0.024-0.034), and 0.046 (95% CI, 0.037-0.054) mm. Bland-Altman and locally weighted scatterplot-smoothing analyses showed excellent agreement between measures with no variation in discrepancies vis-à-vis the target measurement. These data establish previously undefined estimates of measurement variability relevant for in vivo sonographic studies of AAA regression in a commonly studied mouse model.

Acute Mechanical Effect of Right Ventricular Pacing at Different Sites Using Velocity Vector Imaging

Velocity vector imaging (VVI) allows noninvasive measurement of left ventricular (LV) strain and rotation angle-independently. We investigated strain, rotation and myocardial synchrony when pacing at different sites in the right ventricle to determine which site yields the most physiological pacing, as determined with VVI imaging. Thirty-one patients with normal LV function referred for elective electrophysiology exam were used in this study. Catheters (6F quadripolar) were positioned in the right atrium, right ventricular apex, right ventricular outflow tract, and His bundle after electrophysiology exam was done. Regional and global LV circumferential strain (CS), radial strain (RS), and LV rotation of LV short-axis measurements were obtained. Two dyssynchrony parameters (AS-P delay and SDt(6S)) of CS and RS were obtained. Compare these values among each pacing, respectively. CS, RS, and twist, which represent the LV systolic function, were significantly reduced in RVOT pacing and RVA pacing than RA pacing. Two dyssynchrony parameters (AS-P delay and SDt(6S)) were significantly longer in response to RVOT or RVA pacing compared to RA pacing. No significant differences were found between RVOT pacing and RVA pacing. CS and RS were obviously reduced in the regions surrounding the pacing site. There was no significant difference in CS, RS, twist, and mechanical dyssynchrony parameters when comparing His and RA pacing. Among these alternate right ventricular pacing locations, His bundle pacing is most like physiological pacing. Both RVOT pacing and RVA pacing worsen the normal LV systolic function with regard to strain, twist, and mechanical dyssynchrony along the LV short axis.

Multi-modality morphological correlation of axillary lymph nodes

The goal of this study is to develop a computerized method that identifies a specific axillary lymph node (ALN) seen on ultrasound (US) with its most likely corresponding node on breast MRI (BMRI). This goal is an important step in developing a preoperative non-invasive method for staging breast cancer on the basis of multi-modality imaging. Twenty patients with newly diagnosed breast cancer were scanned on US and MRI. Two expert breast imaging radiologists independently correlated ALNs seen on US with BMRI, and this correlation was used as the gold standard. To correlate ALNs on US and BMRI, the cortex and hilum of each ALN was segmented using an ellipse fitting algorithm, then the ALN long and short axes and maximum cortical thickness (MCT) were computed. Three ALNs were chosen as candidates from the BMRI datasets for each lymph node seen on US. Finally, the Euclidean distances across all measurements between the US ALN and each of the three BMRI candidates were computed, and the smallest distance was reported as the correlation result. Using the expert radiologists identified correlated BMRI slice as the ground truth, the shortest Euclidean distance successfully identified the same lymph node as the radiologists in 13 out of 16 ALNs (81.25%). In negative ALNs, the standard deviation for long and short axes was relatively large but that of maximum cortical thickness was small. Average maximum cortical thickness and its standard deviation measured in US were very close to those measured in MRI. There were no significant differences among the long axis, short axis, and MCT measurements between US and MRI-T2 weighted sequence (P > 0.05 paired t-test). We performed a feasibility study which showed that computerized measurements of ALNs might be used to identify the same ALN on different modalities such as US and BMRI. This type of correlation would be valuable as it would allow the use of combined imaging parameters to be applied to the evaluation of ALNs in patients with breast cancer. It is hoped that the combined multi-modality information would provide a more robust non-invasive method of staging the axilla than is currently available.

Placental weight, digitally derived placental dimensions at term and their relationship to birth weight

Objective. A few recent studies have investigated the relationship between birth weight and digitally derived placental dimensions, and no standardised methodology has been used. The aims of this study are to compare manually derived placental measurements with those derived digitally and to establish the relationship of birth weight to the placental weight and circumference.Methods. Three hundred fifty-one consecutive unselected women with singleton pregnancy delivering in a tertiary maternity unit at 37–42 weeks were recruited. Manual and digital placental axis measurements (using calibrated digital imaging and ‘Image J’ software) were obtained and the circumference derived. The relationship between the two methods was assessed using a Bland–Altman plot analysed. The relationship between z-scores of birth weight, placental weight and placental circumference was investigated.Results. Manually and digitally obtained placental long axis, short axis and circumference measurements show close correlation (r = 0.70, 0.70 and 0.83, respectively). The z score of birth weight is significantly correlated with the z score of placental weight (r = 0.59, p < 0.001) and z score placental digital circumference (r = 0.40, p < 0.001). Birth weight:placental weight ratio is 7.20 and birth weight:placental circumference = 64.57 g/cm.Conclusion. There is close though not perfect agreement between the manual and digital placental measurements. Birth weight is strongly correlated with placental weight and circumference at term.