Pierre-Hugues Vivier

Cardiac MRI assessment of right ventricular function in acquired heart disease: factors of variability.

RATIONALE AND OBJECTIVES To evaluate intra- and inter-observer variability of right ventricular (RV) functional parameters as evaluated by cardiac magnetic resonance imaging (MRI) in patients with acquired heart disease (AHD), and to identify factors associated with an increased variability. MATERIALS AND METHODS Sixty consecutive patients were enrolled. Right and left ventricular (LV) volumes, ejection fraction, and mass were determined from short-axis cine sequences. All analyzes were performed twice by three observers with various training-degree in cardiac MRI. Intra- and inter-observer variability was evaluated. The impact on variability of each of the following parameters was assessed: observers experience, basal and apical slices selection, end-systolic phase selection, and delineation. RESULTS Mean segmentation time ranged 9.8-19.0 minutes for RV and 6.4-9.2 minutes for LV. Variability of RV functional parameters measurement was strongly influenced by previous observers experience: it was two to three times superior to that of LV, even for the most experienced observer. High variability in the measurement of RV mass was observed. For both ventricles, selection of the basal slice and delineation were major determinants of variability. CONCLUSION As compared to LV, RV function assessment with cardiac MRI in AHD patients is much more variable and time-consuming. Observers experience, selection of basal slice, and delineation are determinant.

Diagnostic accuracy and variability of three semi-quantitative methods for assessing right ventricular systolic function from cardiac MRI in patients with acquired heart disease

ObjectivesTo evaluate the diagnostic accuracy and variability of 3 semi-quantitative (SQt) methods for assessing right ventricular (RV) systolic function from cardiac MRI in patients with acquired heart disease: tricuspid annular plane systolic excursion (TAPSE), RV fractional-shortening (RVFS) and RV fractional area change (RVFAC).MethodsSixty consecutive patients were enrolled. Reference RV ejection fraction (RVEF) was determined from short axis cine sequences. TAPSE, RVFS and RVFAC were measured on a 4-chamber cine sequence. All SQt analyses were performed twice by 3 observers with various degrees of training in cardiac MRI. Correlation with RVEF, intra- and inter-observer variability, and receiver operating characteristic (ROC) curve analysis were performed for each SQt method.ResultsCorrelation between RVFAC and RVEF was good for all observers and did not depend on previous cardiac MRI experience (R range = 0.716–0.741). Conversely, RVFS (R range = 0.534–0.720) and TAPSE (R range = 0.482–0.646) correlated less with RVEF and depended on previous experience. Intra- and inter-observer variability was much lower for RVFAC than for RVFS and TAPSE. ROC analysis demonstrated that RVFAC <41% could predict a RVEF <45% with 90% sensitivity and 94% specificity.ConclusionsRVFAC appears to be more accurate and reproducible than RVFS and TAPSE for SQt assessment of RV function by cardiac MRI.

MR urography in children. Part 2: how to use ImageJ MR urography processing software.

MR urography (MRU) is an emerging technique particularly useful in paediatric uroradiology. The most common indication is the investigation of hydronephrosis. Combined static and dynamic contrast-enhanced MRU (DCE-MRU) provides both morphological and functional information in a single examination. However, specific post-processing must be performed and to our knowledge, dedicated software is not available in conventional workstations. Investigators involved in MRU classically use homemade software that is not freely accessible. For these reasons, we have developed a software program that is freely downloadable on the National Institute of Health (NIH) website. We report and describe in this study the features of this software program.

Uro-IRM fonctionnelle chez l’enfant

Sinonasal cavities: CT imaging features of anatomical variants and surgical risk. MR Urography (MRU) provides both morphologic and functional information without radiation exposure. It enables the assessment of split renal function, excretion, and quantification of obstruction. MRU is thus complementary to ultrasonography in the assessment of pre- and post-natal obstructive uropathies in children. If available, MRU should be definitely preferred to intravenous urography.

ESPR uroradiology task force and ESUR paediatric working group: imaging recommendations in paediatric uroradiology, part IV: Minutes of the ESPR uroradiology task force mini-symposium on imaging in childhood renal hypertension and imaging of renal trauma in children.

Two new recommendations of the European Society of Radiology task force and the European Society of Uroradiology workgroup on paediatric uroradiology are presented. One deals with diagnostic imaging in children after trauma to the urinary tract—renal trauma, in particular. The other concerns the evaluation of suspected renal hypertension. Available data in the paediatric literature are either unsatisfactory or controversial for both of these clinical settings. Therefore, the following consensus-based proposals aim at outlining effective imaging algorithms to reduce invasive imaging procedures while optimising diagnostic accuracy. The objective of following a more uniform imaging approach is to facilitate future meta-analysis as well as multicentre and other more evidence-based studies. The practise in paediatric radiology is typically based on local availability and on the limitations of professional expertise and equipment, balanced against the perceived needs of the individual child. Although this is unlikely to change in the near future, it does not release the physicians in charge of diagnostic imaging from their responsibility in choosing and providing state-of-the-art imaging and management protocols that are adapted specifically for use in children.

Walker-Warburg syndrome diagnosed by findings of typical ocular abnormalities on prenatal ultrasound.

Walker-Warburg syndrome (WWS) is a rare, lethal autosomal recessive disorder characterized by congenital muscular dystrophy and brain and eye anomalies. A prenatal finding of hydrocephalus associated with posterior fossa anomalies and/or encephalocele is nonspecific, whereas additional ocular anomalies are typical for WWS. We report a fetus of consanguineous parents found to have encephalocele at US in week 15 of gestation. The parents did not wish to terminate the pregnancy. Follow-up US revealed bilateral abnormal ocular echoic structures suggesting a major form of persistent primary vitreous. WWS was suspected. The POMT2 mutation confirmed this diagnosis. In hydrocephalus associated with posterior fossa anomalies and/or encephalocele, we recommend detailed US examination of the fetal eyes. Ocular anomalies in this context strongly suggest WWS.

In Vitro Assessment of a 3D Segmentation Algorithm Based on the Belief Functions Theory in Calculating Renal Volumes by MRI

OBJECTIVE Renal volumetry is an essential part of split renal function assessment in MR urography. The aim of this study was to assess the accuracy and repeatability of a 3D segmentation algorithm based on the belief functions theory for calculating renal volumes from MR images. MATERIALS AND METHODS The true volumes of 20 animal kidneys of various sizes were obtained by fluid displacement. Each kidney was examined using two different MR units. Three-dimensional proton density-weighted acquisitions with an incremental slice thickness were performed. The MR volume was then measured with a segmentation algorithm based on the belief functions theory. Two independent observers performed all segmentations twice. Accuracy, intraobserver variability, and interobserver variability were evaluated by the Bland-Altman method. The number and type of manual corrections were recorded as well as the entire processing time. RESULTS The mean renal volume estimated by fluid displacement was 114 mL (range, 38-224 mL). With regard to the renal volumes obtained from assessments of adjacent axial MR images, the maximal SDs of the difference were 2.2 mL (accuracy), 0.6 mL (intraobserver variability), and 1.8 mL (interobserver variability). Segmentation of axial slices provided better accuracy and reproducibility than coronal slices. Overlapped coronal slices yielded poor results because of the partial volume effect. The mean processing time including optional manual modifications was less than 75 seconds. CONCLUSION The belief functions theory can be considered an accurate and reproducible mathematic method to assess renal volume from MR adjacent images.

European Society of Paediatric Radiology abdominal imaging task force recommendations in paediatric uroradiology, part IX: Imaging in anorectal and cloacal malformation, imaging in childhood ovarian torsion, and efforts in standardising paediatric uroradiology terminology

At the occasion of the European Society of Paediatric Radiology (ESPR) annual meeting 2015 in Graz, Austria, the newly termed ESPR abdominal (gastrointestinal and genitourinary) imaging task force set out to complete the suggestions for paediatric urogenital imaging and procedural recommendations. Some of the last missing topics were addressed and proposals on imaging of children with anorectal and cloacal malformations and suspected ovarian torsion were issued after intense discussions and a consensus finding process that considered all evidence. Additionally, the terminology was adapted to fit new developments introducing the term pelvicalyceal dilatation/distension (PCD) instead of the sometimes misunderstood hydronephrosis. The present state of paediatric urogenital radiology was discussed in a dedicated minisymposium, including an attempt to adapt terminology to create a standardised glossary.

Segmentation of polycystic kidneys from MR images

Polycystic kidney disease (PKD) is a disorder characterized by the growth of numerous fluid filled cysts in the kidneys. Measuring cystic kidney volume is thus crucial to monitoring the evolution of the disease. While T2-weighted MRI delineates the organ, automatic segmentation is very difficult due to highly variable shape and image contrast. The interactive stereology methods used currently involve a compromise between segmentation accuracy and time. We have investigated semi-automated methods: active contours and a sub-voxel morphology based algorithm. Coronal T2- weighted images of 17 patients were acquired in four breath-holds using the HASTE sequence on a 1.5 Tesla MRI unit. The segmentation results were compared to ground truth kidney masks obtained as a consensus of experts. Automatic active contour algorithm yielded an average 22% ± 8.6% volume error. A recently developed method (Bridge Burner) based on thresholding and constrained morphology failed to separate PKD from the spleen, yielding 37.4% ± 8.7% volume error. Manual post-editing reduced the volume error to 3.2% ± 0.8% for active contours and 3.2% ± 0.6% for Bridge Burner. The total time (automated algorithm plus editing) was 15 min ± 5 min for active contours and 19 min ± 11 min for Bridge Burner. The average volume errors for stereology method were 5.9%, 6.2%, 5.4% for mesh size 6.6, 11, 16.5 mm. The average processing times were 17, 7, 4 min. These results show that nearly two-fold improvement in PKD segmentation accuracy over stereology technique can be achieved with a combination of active contours and postediting.

Idiopathic varicocele in adolescents: risks of the inguinal approach.

INTRODUCTION The aim of this study was to evaluate the medium-term results and complications of open inguinal varicocelectomy, including vein ligation, intraoperative venography, and antegrade sclerotherapy. MATERIALS AND METHODS Sixty-four children were treated between 2000 and 2009 for idiopathic varicocele. Fifty children were examined 6 months after surgery. In 2010, 22 patients were recalled for testicular ultrasound scans (US) to evaluate the medium-term results of the technique. RESULTS The mean age of the children was 12.8 years at first consultation. Of the 50 cases, 35 children were asymptomatic, 13 experienced pain, 3 suffered from discomfort, and 1 had testicular asymmetry. Thirteen children had delayed left testicular growth compared with the right testis. The mean age at surgery was 13.3 years, and follow-up duration was 8.3 months ± 13.9. Thirty-eight patients achieved good results postsurgery; there was varicocele recurrence in 3, testicular hypotrophy in 7, and complete testicular atrophy in 2 patients. CONCLUSION Naked eye inguinal surgical ligation does not appear to be safe enough to treat young adolescents, with the theoretical risk of a decrease in fertility in the future. In teams which are untrained in microsurgical or laparoscopic varicocelectomy, we suggest referring adolescent patients to a radiologist for embolization.