Forensic age assessment of the knee: proposal of a new classification system using two-dimensional ultrasound volumes and comparison to MRI.

OBJECTIVES: To assess epiphyseal growth plate closure of the knee for forensic age estimation using an ultrasound (US)-based method and to compare the findings with MRI. METHODS: Thirty-three healthy male individuals (age, 14.4-19.3 years) were prospectively evaluated for epiphyseal growth plate closure of the right knee by recordings of two-dimensional US volumes and a high-resolution T1-weighted MRI sequence. The degree of epiphyseal growth plate closure was rated independently by two readers for each method using a modality specific three-point scale that differentiates between an open physis (S1), a partially closed physis (S2), and a closed physis (S3). RESULTS: The inter-rater agreement was high for the US (Cohen's kappa (CK): femur 95.2%, tibia 81.3%, fibula 86.3%) and the MRI method (CK: femur 70.2%, tibia 90.8%, fibula 79.8%). The degree of growth plate closure associated positively with advancing age. The US system showed a clearer separation of median ages with lower overlap than the MRI system. Open growth plates on minors (< S3 on femur and tibia) were identified by US with higher sensitivity (1.0 vs. 0.7) and slightly lower specificity (0.7 vs. 0.85) compared with MRI. The examination time was substantially shorter on US than on MRI (2.65 ± 0.91 min vs. 24.72 ± 2.72 min; p < 0.001). CONCLUSIONS: The US method for evaluation of growth plate closure of the knee can reliably assign male individuals to different ossification stages and identifies minors with high accuracy. More studies with larger numbers are needed to further evaluate this method. KEY POINTS: • US is feasible to determine the degree of epiphyseal growth plate closure of the knee, shows a high degree of reliability, and is comparable to MRI. • US of the knee can detect open growth plates on male minors with high accuracy. • US of the knee may be used as a fast, non-invasive imaging tool for forensic age estimation to identify male minors.

Impact of chest wall deformity on cardiac function by CMR and feature-tracking strain analysis in paediatric patients with Marfan syndrome.

OBJECTIVES: To evaluate systolic cardiac dysfunction in paediatric MFS patients with chest wall deformity using cardiac magnetic resonance (CMR) imaging and feature-tracking strain analysis. METHODS: Forty paediatric MFS patients (16 ± 3 years, range 8-22 years) and 20 age-matched healthy controls (16 ± 4 years, range 11-24 years) were evaluated retrospectively. Biventricular function and volumes were determined using cine sequences. Feature-tracking CMR was used to assess global systolic longitudinal (GLS), circumferential (GCS) and radial strain (GRS). A dedicated balanced turbo field echo sequence was used to quantify chest wall deformity by measuring the Haller index (HI). RESULTS: LV volumes and ejection fraction (EF) were similar in MFS patients and controls. There was a trend for lower right ventricular (RV) volume (75 ± 17 vs. 81 ± 10 ml/m2, p = 0.08), RV stroke volume (41 ± 12 vs. 50 ± 5 ml/m2, p < 0.001) and RVEF (55 ± 10 vs. 62 ± 6%, p < 0.01) in MFS patients. A subgroup of MFS patients had an increased HI compared to controls (4.6 ± 1.7 vs. 2.6 ± 0.3, p < 0.001). They demonstrated a reduced RVEF compared to MFS patients without chest wall deformity (50 ± 11% vs. 58 ± 8%, p = 0.01) and controls (p < 0.001). LV GLS was attenuated when HI ≥ 3.25 (- 16 ± 2 vs. - 18 ± 3%, p = 0.03), but not GCS and GRS. LV GLS (p < 0.01) and GCS (p < 0.0001) were attenuated in MFS patients compared to controls, but not GRS (p = 0.31). RV GLS was attenuated in MFS patients compared to controls (- 21 ± 3 vs. - 23 ± 3%, p < 0.05). CONCLUSION: Chest wall deformity in paediatric MFS patients is associated with reduced RV volume, ejection fraction and GLS. Feature-tracking CMR also indicates impairment of systolic LV function in paediatric MFS patients. KEY POINTS: • Paediatric Marfan patients demonstrate reduced RV volume and ejection fraction compared to healthy controls. • A concordant attenuation in RV global longitudinal strain was observed in Marfan patients, while the RV global circumferential strain was increased, indicating a possible compensatory mechanism. • Subgroup analyses demonstrated alterations in RV ejection fraction and RV/LV global strain parameters, indicating a possible association of severe chest wall deformity with biventricular dysfunction in paediatric Marfan patients.

Automated age estimation of young individuals based on 3D knee MRI using deep learning.

Age estimation is a crucial element of forensic medicine to assess the chronological age of living individuals without or lacking valid legal documentation. Methods used in practice are labor-intensive, subjective, and frequently comprise radiation exposure. Recently, also non-invasive methods using magnetic resonance imaging (MRI) have evaluated and confirmed a correlation between growth plate ossification in long bones and the chronological age of young subjects. However, automated and user-independent approaches are required to perform reliable assessments on large datasets. The aim of this study was to develop a fully automated and computer-based method for age estimation based on 3D knee MRIs using machine learning. The proposed solution is based on three parts: image-preprocessing, bone segmentation, and age estimation. A total of 185 coronal and 404 sagittal MR volumes from Caucasian male subjects in the age range of 13 and 21 years were available. The best result of the fivefold cross-validation was a mean absolute error of 0.67 ± 0.49 years in age regression and an accuracy of 90.9%, a sensitivity of 88.6%, and a specificity of 94.2% in classification (18-year age limit) using a combination of convolutional neural networks and tree-based machine learning algorithms. The potential of deep learning for age estimation is reflected in the results and can be further improved if it is trained on even larger and more diverse datasets.

Intrathecal Administration of Nusinersen in Pediatric SMA Patients with and without Spine Deformities: Experiences and Challenges over 3 Years in a Single Center.

Spinal muscular atrophy (SMA) is a rare neurodegenerative disease leading to progressive muscular atrophy, respiratory failure, and premature death. Secondary thorax and spine deformities are frequent. In July 2017, the antisense oligonucleotide nusinersen (Spinraza) was approved for the recurrent lifelong intrathecal treatment of SMA in Europe. Lumbar punctures are challenging especially in SMA patients with severe spine deformities and after spine surgery. In the light of alternative SMA therapies that are available or are expected to be available soon and which are administered orally or via one-time infusion, an appraisal of the established therapy is significant. Discussion about which therapy is the best for each individual patient will have to include not only the safety and efficacy of data but also the application form and its burden for the patient and the health care system. Therefore, we analyzed our 3-year experiences and challenges with 478 lumbar puncture procedures in 61 pediatric SMA patients with and without spine deformities or instrumentation.

A 2-year follow-up MRI study for the evaluation of an age estimation method based on knee bone development.

Age estimation is an actual topic in the area of forensic medicine with a special focus on the age limits of 16 and 18 years. Current research on this topic relies on retrospective data of inhomogeneous populations relating to sex, age range, and socioeconomic status. In this work, we present a 2-year follow-up study for the evaluation of an age estimation method on a prospective magnetic resonance imaging (MRI) knee data collective of a homogeneous population. The study includes 40 male subjects from northern Germany aged 14 to 21 years. Three MRI examinations were evenly acquired within 2 years for each subject. As a first evaluation, a three-stage system was used to assess the ossification status of the knee (I:"open", II:"partially ossified", III:"fully ossified"). Three raters assessed the growth plate of the distal femur, proximal tibia, and proximal fibula based on central 2D slices. A good inter-rater agreement was attained (κ = 0.84). All subjects younger than 18 years were rated as stage I and had a cumulative knee score (SKJ) ≤ 5. Based on the follow-up datasets, new parameters quantifying the intra-individual ossification process were calculated. The results of this follow-up analysis show a different start, end, and speed of each growth plate's maturation as well as an ossification peak for individuals at the age of 16. The generated MRI database provides new insights into the ossification process over time and serves as a basis for further evaluations of age estimation methods.

Automated segmentation of the knee for age assessment in 3D MR images using convolutional neural networks.

Age assessment is used to estimate the chronological age of an individual who lacks legal documentation. Recent studies indicate that the ossification degree of the growth plates in the knee joint correlates with chronological age of adolescents and young adults. To verify this hypothesis, a high number of datasets need to be analysed. An approach which enables an automated detection and analysis of the bone structures may be necessary to handle large datasets. The purpose of this study was to develop a fully automatic 2D knee segmentation based on 3D MR images using convolutional neural networks. A total of 76 datasets were available and divided into a training set (74%), a validation set (13%) and a test set (13%). Multiple preprocessing steps were applied to correct image intensity values and to reduce the image size. Image augmentation was employed to virtually increase the dataset size for training. The proposed architecture for the segmentation task resembles the encoder-decoder model type used for the U-Net. The trained network achieved a dice similarity coefficient score of 98% compared to the manual segmentations and an intersection over union of 96%. The precision and recall of the model were balanced, and the error was only 1.2%. No overfitting was observed during training. As a proof of concept, the predicted segmentations were used for the age estimation of 145 subjects. Initial results show the potential of this approach attaining a mean absolute error of 0.48 ± 0.32 years for a test set of 14 subjects. The proposed automated segmentation can contribute to faster, reproducible and potentially more reliable age estimation in the future.

Persistence of post-operative color Doppler abnormalities is linked to reduced graft survival in pediatric patients after liver transplantation.

Color Doppler US is a readily available imaging modality for the evaluation of liver transplants. The aim of our study was to evaluate the temporal course of color Doppler US findings in children after LTX and to investigate the effect of resolving and persisting abnormalities during follow-up on long-term outcome. All children who underwent LTX during January 2000 until December 2003 (155 LTX in 137 patients, 75 male and 62 female; mean age at LTX 4.1 ± 4.8 years; range, 0.1-16.3 years) were retrospectively evaluated. Following a predefined ultrasound protocol with prospective documentation, intraoperative, post-operative, and follow-up examinations were evaluated for color Doppler abnormalities. The time of occurrence and temporal course of the findings were recorded. Graft survival rates and graft survival times were compared. Abnormal color Doppler US examinations were noted in 98 of 155 grafts during the entire observational period (63.2%). In 57 of 98 grafts (58.2%), abnormalities were limited to the perioperative period (<30 days after LTX). Survival of grafts with transient perioperative abnormalities was similar to transplantations with regular color Doppler US examinations (graft survival rates, 80.7% vs 84.2%, P = .622; mean graft survival time, 2596.92 vs 2511.40 days, P = .67). Grafts with persisting color Doppler US abnormalities in the follow-up period (>30 days after LTX; 37/98 LTX, 37.8%) showed reduced survival compared with regular courses (graft survival rate 62.2% vs 80.7%, P = .047), indicating underlying organ-specific alterations. Standardized longitudinal evaluation during the perioperative and the follow-up period can enhance the prognostic capabilities of color Doppler US in children following LTX.

Hepatic shear wave elastography in children under free-breathing and breath-hold conditions.

OBJECTIVES: To compare hepatic 2D shear wave elastography (2D SWE) in children between free-breathing and breath-hold conditions, in terms of measurement agreement and time expenditure. METHODS: A cohort of 57 children (12.7±4.3 years) who underwent standardized 2D SWE between May and October 2015 were retrospectively evaluated. Liver elastograms were obtained under free-breathing and breath-hold conditions and time expenditure was measured. Median stiffness, interquartile range (IQR), and IQR/median ratio were calculated based on 12, six, and three elastograms. Results were compared using Pearson correlation coefficient, intraclass correlation coefficient (ICC), Bland-Altman analysis, and Student's t. RESULTS: Median liver stiffness under free-breathing and breath-hold conditions correlated strongly (7.22±4.5kPa vs. 7.21±4.11kPa; r=0.97, P<0.001). Time to acquire 12 elastograms with free-breathing was lower than that with breath-holding (79.3±32.5sec vs. 143.7±51.8sec, P<0.001). Results for median liver stiffness based of 12, six, and three elastograms demonstrated very high agreement for free-breathing (ICC 0.993) and for breath-hold conditions (ICC 0.994). CONCLUSIONS: Hepatic 2D SWE performed with free-breathing yields results similar to the breath-hold condition. With a substantially lower time requirement, which can be further reduced by lowering the number of elastograms, the free-breathing technique may be suitable for infants and less cooperative children not capable of breath-holding. KEY POINTS: • Hepatic 2D SWE performed with free-breathing yields results similar to breath-hold condition. • Benefit of the free-breathing approach is the substantially lower time requirement. • Lowering the number of elastograms can further reduce time expenditure. • Free-breathing 2D SWE is suitable in children with suspected liver disease.

Diffusion-weighted imaging of the kidneys in haemolytic uraemic syndrome.

OBJECTIVES: To evaluate the kidneys of patients with haemolytic uraemic syndrome (HUS) using diffusion-weighted imaging (DWI) and Doppler ultrasound (US) compared with healthy controls. MATERIALS AND METHODS: Fifteen patients (mean age 33.3 years; three male; 12 female) with diarrhoea-positive HUS and 15 healthy volunteers were prospectively evaluated with DWI and Doppler US. A total apparent diffusion coefficient (ADCTOT), and ADCs predominantly reflecting microperfusion (ADCLOW) and diffusion (ADCHIGH) were calculated. Doppler US evaluated renal vascularity and flow. RESULTS: When compared with controls, kidneys affected by HUS showed reduced cortical ADC values (ADCTOT 1.79±0.22 vs. 2.04±0.1x10-3 mm2/s, P 0.001), resulting in either low corticomedullary differences (11/15 patients) or an inverted corticomedullary pattern (4/15 patients). Reduction of cortical ADC values was associated with a decrease of cortical vascularity on Doppler US (ADCTOT, P<0.001; ADCLOW, P 0.047). Kidneys with complete absence of the cortical vasculature on Doppler US (four patients) also demonstrated limited diffusion (ADCHIGH, P 0.002). Low glomerular filtration rate, requirement for haemodialysis during hospitalization, and longer duration of haemodialysis were associated with decreased cortical diffusivity (ADCTOT: P 0.04, 0.007, and <0.001, respectively). CONCLUSION: DWI shows qualitative and quantitative abnormalities in kidneys affected by HUS, thereby extending the non-invasive assessment of renal parenchymal damage. KEY POINTS: • In HUS, DWI is feasible for functional characterization of kidney involvement. • Kidneys affected by HUS showed reduced cortical diffusivity. • Decreased cortical diffusivity was associated with lower kidney function. • Requirement and duration of haemodialysis was linked to degree of cortical alterations.

Functional assessment of the kidneys in a 10 month-old child with renal artery stenosis by intravoxel incoherent motion.

Renovascular stenosis is an important cause for arterial hypertension in childhood. We report a 10-month-old girl with arterial hypertension caused by right-sided renal artery stenosis detected by Doppler ultrasound. Magnetic resonance imaging (MRI) was performed before renal artery angioplasty to depict vascular anatomy in detail and to retrieve additional functional information of the kidneys by analysis of intravoxel incoherent motion (IVIM). The value of quantitative diffusion weighted imaging of the kidneys prior to percutaneous transluminal renal angioplasty (PTRA) is discussed.

The Downside of Fat: Avoiding and Treating Complications.

Three-dimensional facial volume restoration using fat has become widely accepted as an essential component of facial rejuvenation. Transplanted fat has benefits due to its inherently nonallergenic nature. The versatility of fat grafts allows for their use in all types of facial enhancement-improving the appearance of nasolabial folds, mesolabial grooves, flattened cheeks and upper lips, glabellar furrows, lipoatrophy, acne scars, and temporal hollowing. Yet despite its virtues as the ideal filler, autologous fat has its shortcomings with risks of complications. Our objective in this article is to present a systematic approach demonstrating the complications that can occur with each step of autologous fat grafting in facial rejuvenation and offering pearls to avoid and treat these complications.

Intraindividual comparison of image quality using retrospective and prospective respiratory gating for the acquisition of thin sliced four dimensional multidetector CT of the thorax in a porcine model.

PURPOSE: To intraindividually compare image quality and anatomical depiction of the lung and mediastinum using retrospective and prospective respiratory gating techniques for the acquisition of 4D-multidetector computed tomography (MDCT) of the chest in a porcine model. MATERIALS AND METHODS: Twelve trachealy intubated domestic pigs underwent 64-row MDCT of the thorax. For retrospective and prospective gating the automated respiratory frequency was adjusted to 10, 14, 18, and 22 respiratory cycles per minute. Further, free breathing MDCT scans of the lung were performed at the same respiratory settings. A breathhold scan was acquired which served as the reference standard. Three reviewers independently analyzed the MDCT data applying a 4-point-grading scale regarding the degree of artifacts observed and anatomical depiction (1, excellent, no artifacts; 4, nondiagnostic due to severe artifacts). For statistical analysis the Wilcoxon matched pairs and Chi-square test were used. RESULTS: Breathhold imaging allowed for the highest image quality (mean value: trachea, 1.00; bronchi, 1.10; lung parenchyma, 1.08; diaphragm, 1.00; pericardium, 1.80). Retrospective gating proved to be of superior image quality compared to prospective gating for all respiratory frequencies. With the respiratory frequency set to 14/min retrospective gating even enabled an identical image quality score as at breathhold. Performing image acquisition during continuous breathing lead to a severe decrease in image quality. CONCLUSIONS: High image quality can be acquired using respiratory gating techniques for 4D-MDCT of the thorax. Retrospective is superior to prospective gating and can be of an equivalent image quality as standard breathhold imaging, but at the cost of a significantly higher radiation dose.

Persistence of Upper Blepharoptosis After Cosmetic Botulinum Toxin Type A.

BACKGROUND: Upper eyelid ptosis after cosmetic botulinum toxin is generally considered short-lived and responsive to apraclonidine ophthalmic drops. The authors present a series with persistent ptosis. OBJECTIVE: To report a series of patients with persistent upper eyelid ptosis after cosmetic botulinum toxin. MATERIALS AND METHODS: A retrospective case review series of 7 patients referred for management after developing visually significant upper eyelid ptosis after cosmetic botulinum toxin type A treatment. RESULTS: Patients in this series experienced persistent visually significant ptosis after cosmetic botulinum toxin lasting from 6 weeks to 13 months. Six of the 7 patients were treated with apraclonidine ophthalmic solution. Apraclonidine drops appeared to be clinically effective within 4 to 6 weeks of the resolution of ptosis. CONCLUSION: Upper eyelid ptosis after cosmetic botulinum toxin can persist for many months after treatment. Based on this series, the authors propose that apraclonidine drops can be used at the time of initial assessment to predict the relative longevity of ptosis after cosmetic botulinum toxin treatment (Level 4 evidence recommendation). After a 1-week trial, responders can be advised that ptosis is likely to resolve in 4 to 6 weeks. Nonresponders should be counseled that resolution may take longer than 6 weeks.

Hepatic Artery Delineation on Ultrasound Volumes Comparing B-Flow and Color Doppler for Postoperative Monitoring of Pediatric Liver Transplants.

(1) Background: Accurate hepatic artery (HA) depiction following pediatric liver transplantation (LT) is essential for graft surveillance but challenging on ultrasound (US). This study assesses if improved HA delineation can be achieved by recording two-dimensional US volumes in Color Doppler (CD) and B-flow technique. (2) Methods: Of 42 consecutive LT, 37 cases were included, and HA delineation was retrospectively rated using a four-point score (0 = HA not detectable, 3 = HA fully detectable, separable from portal vein) within 48 h post-LT (U1) and before discharge (U2). (3) Results: Adding B-flow compared with CD alone showed superior results at neohilar (U1: 2.2 ± 1.0 vs. 1.1 ± 0.8, p < 0.0001; U2: 2.5 ± 0.8 vs. 1.5 ± 0.9, p < 0.0001) and segmental levels (U1: 2.8 ± 0.6 vs. 0.6 ± 0.8, p < 0.0001; U2: 2.8 ± 0.6 vs. 0.7 ± 0.5, p < 0.0001). (4) Conclusions: Standardized US volume recordings combining B-flow and CD can effectively delineate the HA along its vascular course in pediatric LT. The technique should be further evaluated as a standard monitoring instrument to rule out vascular complications after LT.

Cardiovascular magnetic resonance demonstrates reversible atrial dysfunction after catheter ablation of persistent atrial fibrillation.

INTRODUCTION: There is a paucity of data on atrial injury following ablation of persistent atrial fibrillation (AF). This study aimed at assessing reversibility of atrial dysfunction after successful persistent AF ablation using cardiovascular magnetic resonance (CMR). METHODS AND RESULTS: CMR was performed during sinus rhythm (SR) in 20 consecutive patients with persistent AF at baseline (BL) within 24 hours after ablation and after 6-month follow-up (FU). Catheter ablation included atrial substrate modification using the stepwise approach following pulmonary vein isolation (PVI) in order to attempt termination of persistent AF. Active left (LA) and right atrial (RA) function were quantified by calculating the active emptying fraction (AEF) from transvalvular flow profiles using velocity encoded (VENC) CMR. LA appendage (LAA) function was quantified by measurements of peak a-wave velocities from flow profiles perpendicular to the LAA orifice. Peri-atrial edema was assessed using black-blood T2 -weighted CMR. A significant improvement was found in LA-AEF from 18 (12-26)% at BL to 25 (22-35)% at FU (P = 0.0001). Furthermore, RA-AEF significantly increased from 31 (19-35)% at BL to 40 (35-51)% at FU (P < 0.0001). A significant improvement was also found for LAA a-wave velocities from 45 (31-65) cm/s at BL to 62 (49-75) cm/s at FU (P < 0.01). The area of peri-atrial edema on T2 -weighted CMR decreased from 1393 (1098-1797) mm(2) at BL to 24 (1-92) mm(2) at FU (P < 0.0001). CONCLUSION: CMR demonstrates reversibility of LA, LAA, and RA dysfunction associated with resorption of peri-atrial edema in patients with SR after persistent AF ablation.

Precision of pulmonary vein diameter measurements assessed by CE-MRA and steady-state-free precession imaging.

OBJECTIVE: Pulmonary vein (PV) diameter assessment is important for planning and follow-up of PV ablation in atrial fibrillation. Therefore, the aim of our study was to evaluate inter- and intraobserver reliability of PV diameter measurements by contrast-enhanced magnetic resonance angiography (CE-MRA) and ECG-gated 2D multislice unenhanced steady-state-free precession sequences (multislice SSFP). METHODS: Sixty PV diameters in 17 consecutive patients were measured in transverse and coronal orientation with CE-MRA and multislice SSFP by two observers. Statistics to evaluate inter- and intraobserver reliability included Bland-Altman analysis and F-test. RESULTS: Intraobserver limits of agreement (LAG) ranged between ±0.50 cm (transverse) and ±0.86 cm (coronal) for CE-MRA versus ±0.40 cm (transverse) and ±0.67 cm (coronal) for multislice SSFP. Interobserver agreement showed LAG ranging between ±0.59 cm (transverse) and ±0.83 cm (coronal) for CE-MRA versus ±0.34 cm (transverse) and ±0.75 cm (coronal) for multislice SSFP. Intra- and interobserver variances did not reveal significant differences between CE-MRA and multislice SSFP in any orientation (all p-values >0.05). CONCLUSION: Multislice SSFP and CE-MRA enable comparable precision of PV diameter measurements. However, both methods reveal a wide range of intra- and interobserver agreement, which has to be thoroughly considered in clinical use. KEY POINTS: • Unenhanced magnetic resonance imaging can now provide measurement of pulmonary vein diameters • Steady-state-free precession offers a new method of performing unenhanced MR imaging • Both unenhanced and enhanced MRI measurements show wide intra- and interobserver variation • PV diameter measurements assessed by MRI have to be interpreted with care • Nevertheless, unenhanced MRI might replace some CT examinations for pulmonary vein demonstration.

Evaluation of Artifact Appearance and Burden in Pediatric Brain Tumor MR Imaging with Compressed Sensing in Comparison to Conventional Parallel Imaging Acceleration.

Clinical magnetic resonance imaging (MRI) aims for the highest possible image quality, while balancing the need for acceptable examination time, reasonable signal-to-noise ratio (SNR), and lowest artifact burden. With a recently introduced imaging acceleration technique, compressed sensing, the acquisition speed and image quality of pediatric brain tumor exams can be improved. However, little attention has been paid to its impact on method-related artifacts in pediatric brain MRI. This study assessed the overall artifact burden and artifact appearances in a standardized pediatric brain tumor MRI by comparing conventional parallel imaging acceleration with compressed sensing. This showed that compressed sensing resulted in fewer physiological artifacts in the FLAIR sequence, and a reduction in technical artifacts in the 3D T1 TFE sequences. Only a slight difference was noted in the T2 TSE sequence. A relatively new range of artifacts, which are likely technique-related, was noted in the 3D T1 TFE sequences. In conclusion, by equipping a basic pediatric brain tumor protocol for 3T MRI with compressed sensing, the overall burden of common artifacts can be reduced. However, attention should be paid to novel compressed-sensing-specific artifacts.

Impact of probe-induced abdominal compression on two-dimensional shear wave elastography measurement of split liver transplants in children.

PURPOSE: To evaluate the effect of probe-induced abdominal compression of split liver transplants (SLT) in children on 2D-shear wave elastography (SWE) values. MATERIALS AND METHODS: Data from 11 children (4.7 ±â€Š4.8 years) who had undergone SLT and SWE were evaluated retrospectively. Elastograms were obtained with probes placed in an epigastric, midline position on the abdominal wall, with no and slight compression, using convex and linear transducers. For each identically positioned probe and condition, 12 serial elastograms were obtained and the SLT diameter was measured. Liver stiffness and degree of SLT compression were compared. RESULTS: Slight probe pressure resulted in SLT compression, with a shorter distance between the cutis and the posterior margin of the liver transplant than in the measurement with no pressure (curved array, 5.0 ±â€Š1.1 vs. 5.9 ±â€Š1.3 cm, mean compression 15 %±â€Š8 %; linear array, 4.7 ±â€Š0.9 vs. 5.3 ±â€Š1.0 cm, mean compression 12 %±â€Š8 %; both p < 0.0001). The median liver stiffness was significantly greater with slight pressure than with no pressure (curved transducer, 13.38 ±â€Š3.0 vs. 7.02 ±â€Š1.7 kPa, p < 0.0001; linear transducer, 18.53 ±â€Š7.1 vs. 9.03 ±â€Š1.5 kPa, p = 0.0003). CONCLUSION: Slight abdominal compression can significantly increase SWE values in children with left-lateral SLT. To obtain meaningful results and reduce operator dependency in free-hand examinations, probe pressure must be controlled carefully. KEY POINTS: · Probe-induced compression can increase elastography values in split liver transplants in children. · In free-hand examination, probe pressure must be controlled carefully. · Pressure loading can be determined indirectly by the anteroposterior transplant diameter. CITATION FORMAT: · Groth M, Fischer L, Herden U et al. Impact of probe-induced abdominal compression on two-dimensional shear wave elastography measurement of split liver transplants in children. Fortschr Röntgenstr 2023; 195: 905 - 912.