Profile flags: a novel metaphor for probing of T2 maps

This paper describes a tool for visualization of T2 maps of knee cartilage. Given the anatomical scan and the T2 map of the cartilage, we combine the information on the shape and the quality of the cartilage in a single image. The Profile Flag is an intuitive 3D glyph for probing and annotating of the underlying data. It comprises a bulletin board pin-like shape with a small flag on top of it. While moving the glyph along the reconstructed surface of an object, the curve data measured along the pin's needle and in its neighborhood are shown on the flag. The application area of the Profile Flag is manifold, enabling the visualization of pro le data of dense but inhomogeneous objects. Furthermore, it extracts the essential part of the data without removing or even reducing the context information. By sticking Profile Flags into the investigated structure, one or more signifi cant locations can be annotated by showing the local characteristics of the data at that locations. In this paper we are demonstrating the properties of the tool by visualizing T2 maps of knee cartilage.URL:http://www.cg.tuwien.ac.at/research/vis/comrade

Cardiac function and position more than 5 years after pneumonectomy

BACKGROUND: Pneumonectomy not only reduces the pulmonary vascular bed but also changes the position of the heart and large vessels, which may affect the function of the heart. We investigated long-term effects of pneumonectomy on right ventricular (RV) and left ventricular (LV) function and whether this function is influenced by the side of pneumonectomy or the migration of the heart to its new position. METHODS: In 15 patients who underwent pneumonectomy and survived for more than 5 years, we evaluated by dynamic magnetic resonance imaging the function of the RV and LV and the position of the heart within the thorax. RESULTS: Long-term effect of pneumonectomy on the position of the heart is characterized by a lateral shift after right-sided pneumonectomy and rotation of the heart after left-sided pneumonectomy. Postoperatively, heart rate was high (p = 0.006) and stroke volume was low (p = 0.001), compared with the reference values, indicating impaired cardiac function. Patients after right-sided pneumonectomy had an abnormal low RV end-diastolic volume of 99 +/- 29 mL together with a normal LV function. No signs of RV hypertrophy were found. In left-sided pneumonectomy patients, RV volumes were normal whereas LV ejection fraction was abnormally low. CONCLUSIONS: The long-term effects of pneumonectomy on the position of the heart are characterized by a lateral shift in patients after right-sided pneumonectomy and rotation of the heart in patients after left-sided pneumonectomy. Overall, cardiac function in long-term survivors after pneumonectomy is compromised, and might be explained by the altered position of the heart

Pulmonary transit time measurement by contrast-enhanced ultrasound in left ventricular dyssynchrony

Background: Pulmonary transit time (PTT) is an indirect measure of preload and left ventricular function, which can be estimated using the indicator dilution theory by contrast-enhanced ultrasound (CEUS). In this study, we first assessed the accuracy of PTT-CEUS by comparing it with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Secondly, we tested the hypothesis that PTT-CEUS correlates with the severity of heart failure, assessed by MRI and N-terminal pro-B-type natriuretic peptide (NT-proBNP). Methods and results: Twenty patients referred to our hospital for cardiac resynchronization therapy (CRT) were enrolled. DCE-MRI, CEUS, and NT-proBNP measurements were performed within an hour. Mean transit time (MTT) was obtained by estimating the time evolution of indicator concentration within regions of interest drawn in the right and left ventricles in video loops of DCE-MRI and CEUS. PTT was estimated as the difference of the left and right ventricular MTT. Normalized PTT (nPTT) was obtained by multiplication of PTT with the heart rate. Mean PTT-CEUS was 10.5 ± 2.4 s and PTT-DCE-MRI was 10.4 ± 2.0 s (P = 0.88). The correlations of PTT and nPTT by CEUS and DCE-MRI were strong; r = 0.75 (P = 0.0001) and r = 0.76 (P = 0.0001), respectively. Bland–Altman analysis revealed a bias of 0.1 s for PTT. nPTT-CEUS correlated moderately with left ventricle volumes. The correlations for PTT-CEUS and nPTT-CEUS were moderate to strong with NT-proBNP; r = 0.54 (P = 0.022) and r = 0.68 (P = 0.002), respectively. Conclusions: (n)PTT-CEUS showed strong agreement with that by DCE-MRI. Given the good correlation with NT-proBNP level, (n)PTT-CEUS may provide a novel, clinically feasible measure to quantify the severity of heart failure. Clinical Trial Registry: NCT0173583

The Apparent Diffusion Coefficient (ADC) is a useful biomarker in predicting metastatic colon cancer using the ADC-value of the primary tumor

PurposeTo investigate the role of the apparent diffusion coefficient (ADC) as a potential imaging bio-marker to predict metastasis (lymph node metastasis and distant metastasis) in colon cancer based on the ADC-value of the primary tumor.MethodsThirty patients (21M, 9F) were included retrospectively. All patients received a 1.5T MRI of the colon including T2 and DWI sequences. ADC maps were calculated for each patient. An expert reader manually delineated all colon tumors to measure mean ADC and histogram metrics (mean, min, max, median, standard deviation (SD), skewness, kurtosis, 5th-95th percentiles) were calculated. Advanced colon cancer was defined as lymph node mestastasis (N+) or distant metastasis (M+). The student Mann Whitney U-test was used to assess the differences between the ADC means of early and advanced colon cancer. To compare the accuracy of lymph node metastasis (N+) prediction based on morpholigical criteria versus ADC-value of the primary tumor, two blinded readers, determined the lymph node metastasis (N0 vs N+) based on morphological criteria. The sensitivity and specificity in predicting lymph node metastasis was calculated for both readers and for the ADC-value of the primary tumor, with histopathology results as the gold standard.Results There was a significant difference between the mean ADC-value of advanced versus early tumors (p = 0.002). The optimal cut off value was 1179 * 10(-3) mm2/s with an area under the curve (AUC) of 0.83 and a sensitivity and specificity of 81% and 86% respectively to predict advanced tumors. Histogram analyses did not add any significant additional value.The sensitivity and specificity for the prediction of lymph node metastasis based on morphological criteria were 40% and 63% for reader 1 and 30% and 88% for reader 2 respectively. The primary tumor ADC-value using 1.179* 10(-3) mm2/s as threshold had a 100% sensitivity and specificity in predicting lymph node metastasis.ConclusionThe ADC-value of the primary tumor has the potential to predict advanced colon cancer, defined as lymph node metastasis or distant metastasis, with lower ADC values significantly associated with advanced tumors. Furthermore the ADC-value of the primary tumor increases the prediction accuracy of lymph node metastasis compared with morphological criteria.</p