High-resolution volume reconstruction from multiple motion-corrupted stacks of 2D slices plays an increasing role for fetal brain Magnetic Resonance Imaging (MRI) studies. Currently existing ...reconstruction methods are time-consuming and often require user interactions to localize and extract the brain from several stacks of 2D slices. We propose a fully automatic framework for fetal brain reconstruction that consists of four stages: 1) fetal brain localization based on a coarse segmentation by a Convolutional Neural Network (CNN), 2) fine segmentation by another CNN trained with a multi-scale loss function, 3) novel, single-parameter outlier-robust super-resolution reconstruction, and 4) fast and automatic high-resolution visualization in standard anatomical space suitable for pathological brains. We validated our framework with images from fetuses with normal brains and with variable degrees of ventriculomegaly associated with open spina bifida, a congenital malformation affecting also the brain. Experiments show that each step of our proposed pipeline outperforms state-of-the-art methods in both segmentation and reconstruction comparisons including expert-reader quality assessments. The reconstruction results of our proposed method compare favorably with those obtained by manual, labor-intensive brain segmentation, which unlocks the potential use of automatic fetal brain reconstruction studies in clinical practice.
Abstract Objectives We compared exercise echocardiography and exercise cardiac magnetic resonance imaging with simultaneous invasive pressure registration (ExCMRip ) for the assessment of pulmonary ...vascular and right ventricular (RV) function. Background Exercise echocardiography may enable early diagnosis of pulmonary vascular disease, but its accuracy is untested. Methods Exercise imaging was performed in 61 subjects (19 athletes, 9 healthy nonathletes, 8 healthy BMPR2 bone morphogenetic protein receptor type II mutation carriers, 5 patients with new or worsening dyspnea after acute pulmonary embolism, and 20 patients with chronic thromboembolic pulmonary hypertension). Echocardiographic variables included mean pulmonary artery pressure (mPAP) and systolic pulmonary artery pressure (sPAP), cardiac output (CO), RV fractional area change, tricuspid annular systolic excursion, and RV end-systolic pressure-area ratio as a surrogate measure of RV contractile reserve. ExCMRip provided measurements of CO, RV ejection fraction, mPAP, sPAP, and RV end-systolic pressure-volume ratio at rest and during exercise. Abnormal pulmonary vascular reserve was defined as mPAP/CO slope >3 mm Hg/l/min by ExCMRip. Results Echocardiographic determination of mPAP/CO was possible in 53 of 61 subjects (87%). mPAP/CO by echocardiography was higher than that obtained by ExCMRip (+0.9 mm Hg/l/min; 95% limits of agreement, −3.6 to 5.4), but enabled accurate identification of patients with abnormal pulmonary vascular reserve (area under the receiver-operating characteristic curve, 0.88 95% confidence interval (CI): 0.77 to 1.00, p < 0.0001). Simplified relationships between sPAP and exercise intensity had similar accuracy in identifying subjects with pulmonary vascular disease (area under the receiver-operating characteristic curve, 0.95 95% CI: 0.88 to 1.01, p < 0.0001). RV fractional area change by echocardiography correlated strongly with RV ejection fraction by ExCMRip , whereas a moderate correlation was found between tricuspid annular systolic excursion and RV ejection fraction. A moderate correlation was found between ratios of peak exercise to resting RV end-systolic pressure-area ratio and RV end-systolic pressure-volume ratio (r = 0.64, p < 0.0001). Conclusions Echocardiographic estimates of RV and pulmonary vascular function are feasible during exercise and identify pathology with reasonable accuracy. They represent valid screening tools for the identification of pulmonary vascular disease in routine clinical practice.
Background Patients with a Fontan circulation achieve lower peak heart rates ( HR ) during exercise. Whether this impaired chronotropic response reflects pathology of the sinoatrial node or is a ...consequence of altered cardiac hemodynamics is uncertain. We evaluated the adequacy of HR acceleration throughout exercise relative to metabolic demand and cardiac output in patients with a Fontan circulation relative to healthy controls. Methods and Results Thirty subjects (20 healthy controls and 10 Fontan patients) underwent cardiac magnetic resonance imaging with simultaneous invasive pressure recording via a pulmonary and radial artery catheter during supine bicycle exercise to near maximal exertion. Adequacy of cardiac index, stroke volume, and HR reserve was assessed by determining the exercise-induced increase (∆) in cardiac index, stroke volume, and HR relative to the increase in oxygen consumption ( VO
). HR reserve was lower in Fontan patients compared with controls (71±21 versus 92±15 bpm; P=0.001). In contrast, increases in HR relative to workload and VO
were higher than in controls. The change in cardiac index relative to the change in VO
(∆cardiac index/∆ VO
) was similar between groups, but Fontan patients had increased ∆ HR /∆ VO
and reduced ∆ stroke volume/∆ VO
compared with controls. There was an early and marked reduction in stroke volume during exercise in Fontan patients corresponding with a plateau in cardiac output at a low peak HR . Conclusions In Fontan patients, the chronotropic response is appropriate relative to exercise intensity, implying normal sinoatrial function. However, premature reductions in ventricular filling and stroke volume cause an early plateau in cardiac output beyond which further increases in HR would be physiologically implausible. Thus, abnormal cardiac filling rather than sinoatrial node dysfunction explains the diminished HR reserve in Fontan patients.
Objective The purpose of this study was to examine the relationship between placental territory and birthweight discordance and vascular anastomoses in monochorionic diamniotic twin placentas from ...pregnancies that were not complicated by twin-to-twin transfusion syndrome with 2 liveborn twins. Study Design Placentas originated from a prospective follow-up study of monochorionic diamniotic twins included in the first trimester. After injection with dyed barium sulphate, a digital x-ray angiography and high-resolution digital photograph were taken. The 2 venous territories were delineated on the angiogram. The diameter of each arterioarterial anastomosis and of each vein that participated in an arteriovenous anastomosis was measured on the digital photograph. Net transfusion over the arteriovenous anastomoses was calculated as the difference between the total venous diameters of the 2 placental parts. Results One hundred placentas were analyzed. Birthweight discordance increased with placental territory discordance ( P < .0001). Arterioarterial diameter ( P < .01), net arteriovenous transfusion ( P < .001), and total anastomotic diameter ( P < .01) increased with placental territory discordance. On the other hand, birthweight discordance for a given placental territory discordance decreased with increasing arterioarterial diameter ( P < .01), net arteriovenous transfusion ( P < .001), and total anastomotic diameter ( P < .01). Conclusion In unequally shared placentas, the 2 fetal circulations are more tightly linked than in equally shared placentas, which may reduce the birthweight discordance for a given placental territory discordance.
To evaluate the diagnostic accuracy of the visual assessment of malignant pleural mesothelioma (MPM) on magnetic resonance (MR) images by using two known visual markers (mediastinal pleural thickness ...and shrinking of the lung) and a newly introduced one (pleural pointillism).
With the approval of the local ethics committee, 100 consecutive patients (mean age, 61.4 years; age range, 18-87 years; 75 men, 25 women) suspected of having MPM pleural abnormalities underwent positron emission tomography/computed tomography and MR imaging, including diffusion-weighted (DW) MR imaging, followed by explorative thoracoscopy or guided biopsy with histopathologic confirmation. Because visual assessment is still the preferred method of image interpretation, the diagnostic accuracy of mediastinal pleural thickening, shrinking lung (hemithorax volume decrease due to fibrosis), and pleural pointillism were examined. Pleural pointillism was denoted by the presence of multiple, hyperintense pleural spots on high-b-value DW images. Histopathologic findings in the surgical specimen served as the reference standard. McNemar tests with Bonferroni correction were used to assess differences in accuracy among the three examined markers.
Of 100 patients, 33 had benign pleural alterations, and 67 had malignant pleural diseases (MPDs); 57 of 67 had MPM. A total of 78 patients received a correct diagnosis (benign vs malignant) on the basis of mediastinal pleural thickening (sensitivity, 81%; specificity, 73%; accuracy, 78%); and 66 patients, on the basis of shrinking lung (sensitivity, 60%; specificity, 79%; accuracy, 66%). The correct diagnosis was indicated on the basis of pleural pointillism in 88 patients (sensitivity, 93%; specificity, 79%; accuracy, 88%).
Visual assessment of pleural pointillism on high-b-value DW images is useful to differentiate MPD from benign alterations, performing substantially better than mediastinal pleural thickness and shrinking lung, and might obviate unnecessary invasive procedures for MPM.
The purpose of this study was to evaluate the accuracy of diffusion-weighted magnetic resonance imaging (DW-MRI) in differentiating HCC from benign cirrhotic lesions compared with conventional ...dynamic contrast-enhanced MRI. Fifty-five patients with cirrhosis underwent conventional and DW-MRI at 1.5 Tesla. Signal intensity ratios (SI
ratio
) of solid liver lesions to adjacent hepatic parenchyma were measured for b0, b100, b600 and b1000, and the apparent diffusion coefficients (ADC) were calculated. In 27 patients, imaging results were compared to histopathology, and in 28 patients, to imaging follow-up. Based on predetermined thresholds, sensitivity and specificity of DW-MRI and conventional MRI were compared. SI
ratio
was significantly different between malignant and benign lesions at all b-values (
P
< 0.0001). No significant difference in ADC was seen (
P
= 0.47). For detection of malignant lesions, DW-MRI with b600-SI
ratio
yielded a sensitivity of 95.2% compared to 80.6% for conventional MRI (
P
= 0.023) and a specificity of 82.7% compared to 65.4% (
P
= 0.064). The improved accuracy was most beneficial for differentiating malignant lesions smaller than 2 cm. DW-MRI with b600-SI
ratio
improved the detection of small HCC and the differentiation of pseudotumoral lesions compared with conventional MRI.
To investigate the use of diffusion-weighted (DW) imaging for differentiating benign lesions from malignant pleural disease (MPD) and to retrospectively assess dynamic contrast material-enhanced ...(DCE) magnetic resonance (MR) imaging acquisitions to find out whether combining these measurements with DW imaging could improve the diagnostic value of DW imaging.
This study was approved by the local ethics committee, and all patients provided written informed consent. Thirty-one consecutive patients with pleural abnormalities suspicious for MPD underwent whole-body positron emission tomography (PET)/computed tomography (CT) and thorax MR examinations. Diagnostic thoracoscopy with histopathologic analysis of pleural biopsies served as the reference standard. First-line evaluation of each suspicious lesion was performed by using the apparent diffusion coefficient (ADC) calculated from the DW image, and the optimal cutoff value was found by using receiver operating characteristic curve analysis. Afterward, DCE MR imaging data were used to improve the diagnosis in the range of ADCs where DW imaging results were equivocal.
Sensitivity, specificity, and accuracy of PET/CT for diagnosis of MPD were 100%, 35.3%, and 64.5%. The optimal ADC threshold to differentiate benign lesions from MPD with DW MR imaging was 1.52 × 10(-3) mm(2)/sec, with sensitivity, specificity, and accuracy of 71.4%, 100%, and 87.1%, respectively. This result could be improved to 92.8%, 94.1%, and 93.5%, respectively, when DCE MR imaging data were included in those cases where ADC was between 1.52 and 2.00 × 10(-3) mm(2)/sec. A total of 20 patients had disease diagnosed correctly, nine had disease diagnosed incorrectly, and two cases were undetermined with PET/CT. DW imaging helped stage disease correctly in 27 patients and incorrectly in four. The undetermined cases at PET/CT were correctly diagnosed at MR imaging.
DW imaging is a promising tool for differentiating MPD from benign lesions, with high accuracy, and supplementation with DCE MR imaging seems to further improve sensitivity.
Microvascular obstruction (MVO) is an important and independent determinant of post-infarct remodeling. Fifty-two patients with a successfully reperfused ST-segment elevation acute myocardial ...infarction (MI) were studied with MRI in the first week and at 4 months post-infarction. On early (i.e., 2-5 min) post-contrast MRI, MVO was detected in 32 patients with an MVO to infarct ratio of 36.3 +/- 24.9%. On late (i.e., 10-25 min) post-contrast MRI, MVO was detected in only 27 patients, with an MVO to infarct ratio of 15.9 +/- 13.9%. MVO infarcts (n = 32) were associated with higher cardiac enzymes (troponin I, P = 0.016), and lower pre-revascularization thrombolysis in myocardial infarction (TIMI) flow (P = 0.018) than non-MVO infarcts (n = 20). Infarct size was larger in MVO infarcts (25.0 +/- 14.3 g) than non-MVO infarcts (12.5 +/- 7.9 g), P = 0.0007. Systolic wall thickening in the infarct and peri-infarct area, and left ventricular (LV) ejection fraction (EF) were worse in MVO (46.1 +/- 7.2%) than non-MVO infarcts (50.5 +/- 6.6%, P = 0.038). At 4 months, MVO infarcts showed more adverse remodeling and lack of functional improvement, whereas non-MVO infarcts improved significantly (LV EF at 4 months, MVO, 47.5 +/- 7.8%, P = 0.31; non-MVO, 55.2 +/- 10.3%, P = 0.0028). In the majority of patients with successfully reperfused ST-segment elevation MI, MVO is observed, whose present and maximal extent can be best evaluated on early post-contrast MRI. Presence of MVO is associated with more extensive infarctions, and characterized by greater adverse LV remodeling and lack of functional recovery.
To prospectively assess changes in lung volume in fetuses with isolated severe congenital diaphragmatic hernia (CDH) after fetoscopic endoluminal tracheal occlusion (FETO) compared with those in ...fetuses with CDH of variable severity who were expectantly managed.
Informed consent was obtained for this ethics committee-approved study. Forty fetuses with severe CDH (lung-to-head ratio < 1 and intrathoracic liver) who underwent FETO and 18 fetuses with CDH of variable severity who were expectantly managed were longitudinally followed up by using magnetic resonance (MR) imaging volume measurements. Fetuses born prior to 32 weeks were excluded from the study. For those undergoing FETO, lung volume responsiveness was defined as the proportionate increase in observed-to-expected (O/E) ratio of total fetal lung volume (TFLV) at 2-5 weeks after FETO compared with the pre-FETO value. Changes in lung volume were compared by using the Mann-Whitney U test. Regression analysis was used to investigate the effect of pre-FETO O/E ratio of TFLV, gestational age at FETO and at delivery, lung volume responsiveness, occlusion period, side of CDH, and balloon removal prior to delivery on survival. Correlation between post-FETO lung volume responsiveness and gestational age at FETO was performed by using linear regression analysis.
A total of 260 MR imaging examinations were performed. For expectantly managed fetuses, O/E ratio of TFLV remained unchanged during gestation, whereas it significantly increased after FETO. Regression analysis demonstrated that pre-FETO O/E ratio of TFLV and lung volume responsiveness at 3.3 weeks after FETO provided significant independent prediction of postnatal survival. There was a significant negative association between lung volume responsiveness and gestational age at FETO.
In fetuses with CDH, pre-FETO O/E ratio of TFLV and lung volume at 3.3 weeks after FETO provide independent prediction of postnatal survival.
http://radiology.rsnajnls.org/cgi/content/full/2522081955/DC1.
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