Can Radiology Technologists be Trained to Measure Leg Length Discrepancies as Accurately as Pediatric Radiologists?

RATIONALE AND OBJECTIVES: Leg length discrepancy studies are labor intensive. They are procedurally simple and represent inefficient use of the radiologists' time and expertise. We hypothesized that radiology technologists could be trained to measure leg length discrepancies, and that their performance would be statistically equivalent to that of board-certified, fellowship-trained pediatric radiologists. MATERIAL AND METHODS: Four radiology technologists were selected to participate in a supervised practice session. They independently measured and calculated leg length discrepancies on 10 randomly selected cases. Their performance was compared to measurements obtained by an experienced pediatric radiologist (reference standard). After 1 week, the technologists repeated their measurements on the same cases, which were resorted to simulate new cases. Intraclass correlation coefficients (ICC) determined interobserver agreement between the technologists and radiologist and intra-observer reliability among the technologists. RESULTS: Among the four technologists, similarity in measurements between session 1 and the reference standard was very high, with ICC values ranging from 0.93 to 0.98 (p < 0.001). The ICC between session 2 and the reference standard was also high, ranging from 0.93 to 0.98 (p < 0.001). Finally, among the four technologists, ICC values between session 1 and session 2 were ≥ 0.96 (p < 0.001). CONCLUSION: Radiology technologists can be rapidly trained to calculate leg length discrepancies as accurately as a board-certified pediatric radiologist. Delegation of this time-consuming task to technologists or radiology assistants will permit radiologists to spend time on more demanding studies, such as studies that require subspecialty training.

Image-Guided Biopsy for Relapsed Neuroblastoma: Focus on Safety, Adequacy for Genetic Sequencing, and Correlation of Tumor Cell Percent With Quantitative Lesion MIBG Uptake.

PURPOSE: Many novel therapies for relapsed and refractory neuroblastoma require tumor tissue for genomic sequencing. We analyze our experience with image-guided biopsy in these patients, focusing on safety, yield, adequacy for next-generation sequencing (NGS), and correlation of tumor cell percent (TC%) with quantitative uptake on 123I-meta-iodobenzylguanidine (MIBG) single-photon emission computed tomography with computed tomography (SPECT/CT). MATERIALS AND METHODS: An 11-year retrospective review of image-guided biopsy on 66 patients (30 female), with a median age of 8.7 years (range, 0.9-49 years), who underwent 95 biopsies (55 bone and 40 soft tissue) of relapsed or refractory neuroblastoma lesions was performed. RESULTS: There were seven minor complications (7%) and one major complication (1%). Neuroblastoma was detected in 88% of MIBG- or fluorodeoxyglucose-avid foci. The overall NGS adequacy was 69% (64% in bone and 74% in soft tissue, P = .37). NGS adequacy within neuroblastoma-positive biopsies was 88% (82% bone and 96% soft tissue, P = .11). NGS-adequate biopsies had a greater mean TC% than inadequates (51% v 18%, P = .03). NGS-adequate biopsies had a higher mean number of needle passes (7.5 v 3.4, P = .0002). The mean tissue volume from NGS-adequate soft-tissue lesions was 0.16 cm3 ± 0.12. Lesion:liver and lesion:psoas MIBG uptake ratios correlated with TC% (r = 0.74, r = 0.72, and n = 14). Mean TC% in NGS-adequate samples was 51%, corresponding to a lesion:liver ratio of 2.9 and a lesion:psoas ratio of 9.0. Thirty percent of biopsies showed an actionable ALK mutation or other therapeutically relevant variant. CONCLUSION: Image-guided biopsy for relapsed or refractory neuroblastoma was safe and likely to provide NGS data to guide therapy decisions. A lesion:liver MIBG uptake ratio of ≥ 3 or a lesion:psoas ratio of > 9 was associated with a TC% sufficient to deliver NGS results.

Translational research in pediatric contrast-enhanced ultrasound.

The role of contrast-enhanced ultrasound (CEUS) imaging is being widely explored by various groups for its use in the pediatric population. Clinical implementation of new diagnostic or therapeutic techniques requires extensive and meticulous preclinical testing and evaluation. The impact of CEUS will be determined in part by the extent to which studies are oriented specifically toward a pediatric population. Rather than simply applying principles and techniques used in the adult population, these studies are expected to advance and augment preexisting knowledge with pediatric-specific information. To further develop this imaging modality for use in children, pediatric-focused preclinical research is essential. In this paper we describe the development and implementation of the pediatric-specific preclinical animal and phantom models that are being used to evaluate CEUS with the goal of clinical translation to children.

Contrast-enhanced ultrasound in pediatric interventional radiology.

There is growing interest in the use of contrast-enhanced ultrasound (CEUS) in diagnostic and interventional radiology. CEUS applications in interventional radiology are performed with intravascular or intracavitary administration of microbubble-based US contrast agents to allow for real-time evaluation of their distribution within the vascular bed or in body cavities, respectively, providing additional information beyond gray-scale US alone. The most common interventional-radiology-related CEUS applications in children have been extrapolated from those in adults, and they include the use of CEUS to guide lesion biopsy and to confirm drain placement in pleural effusions and intra-abdominal fluid collections. Other applications are emerging in interventional radiology for use in adults and children, including CEUS to optimize sclerotherapy of vascular malformations, to guide arthrography, and for lymphatic interventions. In this review article we present a wide range of interventional-radiology-related CEUS applications, emphasizing the current and potential uses in children. We highlight the technical parameters of the CEUS examination and discuss the main imaging findings.

Starting a pediatric contrast ultrasound service: made simple!

The addition of contrast US to an existing pediatric US service requires several preparatory steps. This overview provides a guide to simplify the process. Initially, it is important to communicate to all stakeholders the justifications for pediatric contrast US, including (1) its comparable or better diagnostic results relative to other modalities; (2) its reduction in procedural sedation or anesthesia by avoiding MRI or CT; (3) its reduction or elimination of radiation exposure by not having to perform fluoroscopy or CT; (4) the higher safety profile of US contrast agents (UCA) compared to other contrast agents; (5) the improved exam comfort and ease inherent to US, leading to better patient and family experience, including bedside US exams for children who cannot be transported; (6) the need for another diagnostic option in light of increasing demand by parents and providers; and (7) its status as an approved and reimbursable exam. It is necessary to have an UCA incorporated into the pharmacy formulary noting that only SonoVue/Lumason is currently approved for pediatric use. In the United States this UCA is approved for intravenous administration for cardiac and liver imaging and for vesicoureteric reflux detection with intravesical application. In Europe and China it is only approved for the intravesical use in children. All other applications are off-label. The US scanner needs to be equipped with contrast-specific software. The UCA has to be prepared just before the exam and it is important to strictly follow the steps as outlined in the packaging inserts in order to prevent premature destruction of the microbubbles. The initial training in contrast US is best focused on the frontline staff actually performing the US studies; these might be sonographers, pediatric or interventional radiologists, or trainees. It is important from the outset to educate the referring physicians about contrast US. It is helpful to participate in existing contrast US courses, particularly those with hands-on components.

Balloon occlusion as an adjunctive technique during sclerotherapy of Puig's classified advanced venous malformations.

OBJECTIVE: Puig types 2 through 4 venous malformations (VMs) are challenging to treat with sclerotherapy given their robust systemic outflow. Endovenous balloon occlusion offers a means of temporarily occluding systemic venous outflow to allow for more complete sclerotherapy. This study reviews our experience of implementing this technique in patients with Puig advanced (types 2 through 4) VMs. METHODS: An IRB approved review of treated venous malformations from 2013-2016 revealed 10 patients fitting inclusion criteria. Patient demographics, pre-procedural imaging, intra-procedural technical parameters, and post-procedural follow-up outcomes were recorded. All patients underwent temporary balloon occlusion of a systemic or major draining vein during sclerotherapy. Embolic agents included n-butyl cyanoacrylate glue, sodium tetradecyl sulfate foam, and coils. Standard 5 French angioplasty balloons ranged from 4 to 8 mm diameter and 2 to 8 cm length depending on vessel requiring occlusion. All patients underwent minimum 3-year follow-up questionnaire administration re-assessing resolution of lesion symptomology and post-procedural quality of life (QoL) measures. RESULTS: Of the 10 VMs treated, 2 were Type 2, 6 were Type 3, and 2 were Type 4. More than one sclerotherapy session was required in 7/10 patients (mean: 2, range: 1-4). Most common sites of VM systemic drainage included subclavian, popliteal, internal/external jugular, and basilic veins. All patients had no indication for further sclerotherapy following adjunctive balloon occlusion. No non-target embolization or immediate post-procedural complications occurred. Follow-up questionnaires (mean interval: 3 years 6 months, range: 3 years-3 years 11 months) confirmed the persistence of embolization effects, improved QoL, and no additional sclerotherapy sessions for all patients in the cohort. CONCLUSIONS: Endovenous balloon occlusion as an adjunct to sclerotherapy can be considered when treating patients with types 2-4 venous malformations. This technique lowers the risk of non-target systemic venous embolization, allowing for operator-driven deeper intralesional sclerosant penetration and subsequently maintained treatment efficacy.

MRI for Response Assessment of Extensive Lymphatic Malformations in Children Treated With Sirolimus.

BACKGROUND. Extensive lymphatic malformations (LMs) may cause substantial morbidity. The mammalian target of rapamycin (mTOR) inhibitor sirolimus shows promise for treating vascular anomalies, although response assessment is not standardized. OBJECTIVE. The purpose of this study was to retrospectively characterize changes seen on MRI of children with extensive LMs treated with sirolimus. METHODS. Twenty-five children treated with sirolimus for extensive LMs were included. Baseline MRI was defined as the MRI examination performed closest to therapy initiation; follow-up MRI was defined as the most recent MRI examination performed while the patient was receiving therapy. Two pediatric radiologists independently determined MRI lesion volume by tracing lesion contours on all slices (normalized to patient body surface area expressed in square meters) and determined signal by placing an ROI on the dominant portion of the lesions (normalized to CSF signal) on baseline and follow-up T2-weighted MRI sequences. Interreader agreement was determined, and values were averaged for further analysis. Volume and signal changes were compared with patient, lesion, and treatment characteristics. RESULTS. The mean (± SD) interval between initiation of sirolimus treatment and follow-up MRI was 22.1 ± 13.8 months. The mean lesion volume index on baseline and follow-up MRI was 728 ± 970 and 345 ± 501 mL/m2, respectively (p < .001). Ninety-two percent of children showed a decrease in lesion volume index that was greater than 10% (mean volume change, -46.4% ± 28.2%). Volume change was inversely correlated with age (r = -0.466; p = .02). The mean volume change was -64.7% ± 25.4% in children younger than 2 years old versus -32.0% ± 21.6% in children 2 years old or older (p = .008). The mean volume change was -58.1% ± 24.0% for craniocervical lesions versus -35.5% ± 28.2% for lesions involving the trunk and/or extremities (p = .03). Mean lesion signal ratio on baseline and follow-up MRI was 0.81 ± 0.29 and 0.59 ± 0.26, respectively (p < .001). Mean signal ratio change was -23.8% ± 22.7%. Volume and signal changes were moderately correlated (r = 0.469; p = .02). Volume and signal changes were not associated with sex, lesion subtype, serum concentration of sirolimus, or the interval between sirolimus initiation and follow-up MRI (p > .05). Interreader agreement for volume index change was excellent (intraclass correlation coefficient, 0.983), and that for signal ratio change was moderate to good (intraclass correlation coefficient, 0.764). CONCLUSION. Sirolimus treatment of extensive LMs in children is associated with significant reductions in volume and signal on T2-weighted MRI. The decrease in volume is greater in younger children and craniocervical lesions. CLINICAL IMPACT. The results may facilitate development of standardized MRI-based criteria for assessing the response of vascular malformations to pharmacotherapy.

Postpyloric Balloon Occlusion to Increase Technical Success during Pediatric Percutaneous Gastrostomy/Gastrojejunostomy Tube Placement.

Gastric distension through insufflation is a key step in creating a safe percutaneous window during gastrostomy/gastrojejunostomy (G/GJ) placement; however, poor or incomplete gastric distention can occur, despite the use of glucagon, and lead to rapid egress of air from the stomach into the duodenum. This report describes the adjunctive technique using postpyloric balloon occlusion in 29 patients to maximize gastric insufflation during G/GJ tube placement after failure of conventional methods. Balloon occlusion was successful in salvaging 23 of 29 (79.3%) of G/GJ tube placements without any complications.

Deep Learning Measurement of Leg Length Discrepancy in Children Based on Radiographs.

Background Radiographic measurement of leg length discrepancy (LLD) is time consuming yet cognitively simple for pediatric radiologists. Purpose To compare deep learning (DL) measurements of LLD in pediatric patients to measurements performed by radiologists. Materials and Methods For this HIPAA-compliant retrospective study, radiographs obtained to evaluate LLD in children between January and August 2018 were identified. LLD was automatically measured by means of image segmentation followed by leg length calculation. On training data, a DL model was trained to segment femurs and tibias on radiographs. The validation set was used to select the optimized model. On testing data, leg lengths were calculated from segmentation masks and compared with measurements from the radiology report. Statistical analysis was performed by using a paired Wilcoxon signed-rank test to compare DL calculations and radiology reports. In addition, the measurement time was manually assessed by a pediatric radiologist and automatically assessed by the DL model on a randomly chosen group of 26 cases; the values were compared with the paired Wilcoxon signed-rank test. Results Radiographs obtained to evaluate LLD in 179 children (mean age ± standard deviation, 12 years ± 3; age range, 5-19 years; 89 boys and 90 girls) were evaluated. Radiographs were randomly divided into training, validation, and testing sets and consisted of studies from 70, 32, and 77 patients, respectively. In the training and validation sets, the DL model showed a high spatial overlap between manual and automatic segmentation masks of pediatric legs (Dice similarity coefficient, 0.94). For the testing set, the correlation between radiology reports and DL-calculated lengths of separated femurs and tibias (r = 0.99; mean absolute error [MAE], 0.45 cm), full pediatric leg lengths (r = 0.99; MAE, 0.45 cm), and full LLD (r = 0.92; MAE, 0.51 cm) was high (P < .001 for all correlations). Calculation time for the DL method per radiograph was faster than the mean time for radiologist manual calculation (1 second vs 96 seconds ± 7, respectively; P < .001). Conclusion A deep learning algorithm measured pediatric leg lengths with high spatial overlap compared with manual measurement at a rate 96 times faster than that of subspecialty-trained pediatric radiologists. © RSNA, 2020 See also the editorial by van Rijn and De Luca in this issue.

Association of intracranial arteriovenous malformation embolization with more rapid rate of perfusion in the peri-nidal region on color-coded quantitative digital subtraction angiography.

BACKGROUND: Hemodynamic alterations post-embolization of intracranial arteriovenous malformations (AVMs) may cause delayed edema/hemorrhage in brain parenchyma adjacent to the lesion. OBJECTIVE: To quantify and compare cerebral perfusion changes in the peri-AVM territory pre- and post-embolization using color-coded quantitative digital subtraction angiography (q-DSA). METHODS: Pediatric intracranial AVM embolization procedures performed over a 5 year period were included. DSA images of all patients were retrospectively assessed using syngo iFlow. Regions of interest (ROI) were selected on anteroposterior and lateral q-DSA views: three in the peri-AVM region; two in parenchyma distant from the AVM. Time-to-peak (TTP) contrast enhancement of ROIs and ∆TTP (TTP at the selected ROI minus TTP at either the ipsilateral internal carotid/vertebral artery) were measured. RESULT: 19 pediatric patients with 19 AVMs (9 males/10 females, mean age 12 years) underwent intracranial AVM embolization: 15/19 AVMs were supplied by the anterior circulation and 4/19 by the posterior circulation. Blood flow was significantly slower post-embolization in the draining vein (19/19) (p<0.01), and the venous sinus outflow (17/19) (p<0.01), by mean difference of 2.01±1.31 s and 1.74±2.04 s. There was significantly increased peri-AVM parenchymal perfusion post-embolization (∆TTP=2.20±0.48 s) compared with pre-embolization (∆TTP=2.52±0.42 s), by an average ∆TTP of 0.33±0.53 s (p=0.014). In contrast, there was no perfusion difference (∆TTP=0.03±0.20 s, p=0.8) between pre- and post-embolization in the distant parenchyma. The size of the AVM was not correlated with change in peri-nidal parenchymal perfusion (r=-0.136, p=0.579). CONCLUSION: This study demonstrates more rapid perfusion in the peri-nidal brain parenchyma post-embolization of the AVM, which supports the theory that increased perfusion in normal tissue surrounding the AVM after embolization may underlie some post-procedural complications.

A Low-Cost, Durable and Re-Usable Bladder Phantom: Teaching Intravesical Ultrasound Contrast Administration.

Contrast-enhanced voiding urosonography (ceVUS) is a radiation-free and highly sensitive examination for detecting vesicoureteral reflux and imaging the urethra in children. This examination is performed with ultrasound and intravesical administration of a gas-filled microbubble US contrast agent. The U.S. Food and Drug Administration recently approved the use of a US contrast agent for ceVUS in children. Because of the growing interest among physicians and US technologists in using ceVUS in children, a urinary bladder phantom was developed to teach intravesical ultrasound contrast administration to perform ceVUS procedures. Described here are the preparation and utility of a low-cost, durable and re-usable phantom that simulates the administration, distribution and effects of different US parameters on US contrast agent appearance in the bladder during ceVUS in children.

Pediatric Percutaneous Nephrostomy: A Multicenter Experience.

PURPOSE: To analyze technique, outcomes, and complications of a large series of pediatric percutaneous nephrostomy (PCN) procedures performed at 4 tertiary pediatric centers. MATERIALS AND METHODS: Retrospective multicenter study of PCNs performed during an 11-year period. Six hundred seventy-five PCNs were performed on 441 patients (median age: 4 y, range: 1 d-18 y, median weight: 17 kg, range: 0.7-112 kg); 31% were younger than 1 year. The most frequent indications for PCN procedures included hydronephrosis (57%), calculus (14%), and infection (12%). Forty-five percent of patients had severe and 32% had moderate hydronephrosis. RESULTS: Technical success was 99% (n = 668); 7 failures occurred from lost access, during tract dilatation (n = 5) and during staghorn calculi without dilatation (n = 2). General anesthesia was used in 73% of procedures. Combined ultrasound and fluoroscopy was used in 98% of procedures. Of the 668 procedures, 561 (84%) were primary nephrostomy insertions, and 107 (16%) were a variety of exchanges (secondary catheter insertions). Twenty-four of 675 (4%) were transplanted kidneys. Access sites included lower (47%), mid (28%), and upper (12%) poles and pelvis (11%). Catheters were predominantly 7-8 French (n = 352). The mean catheter dwell time was 25 days (0-220 d). Total primary catheter days were 14,482, with an additional 2,241 days after secondary procedures. Follow-up in 653/668 (98%) procedures documented elective removal (79%) and salvage procedures (21%), which included wire exchange (8.7%), nephroureteral stent/catheter conversion (8.8%), and tube upsizing (3.5%). Periprocedural complications occurred in 30/668 (4.5%) procedures: 1 major (0.1%) self-limiting hematuria requiring transfusion and 29 (4.4%) minor complications. CONCLUSIONS: PCN is safe and successful in children of all ages, with few major complications. PCN in children is associated with specific technical challenges and requires ongoing management tailored to the very young to achieve good outcomes.

Prospective evaluation of MR overlay on real-time fluoroscopy for percutaneous extremity biopsies of bone lesions visible on MRI but not on CT in children in the interventional radiology suite.

Magnetic resonance imaging (MRI) often provides better visualization of bone marrow abnormalities than computed tomography (CT) or fluoroscopy, but bone biopsies are usually performed using conventional CT or, more recently, C-arm CT guidance. Biopsies of bone lesions solely visible on MRI are often challenging to localize and require the operator to review the MRI on a separate console to correlate with MRI anatomical landmarks during the biopsy. The MR overlay technique facilitates such biopsies in the angiographic suite by allowing the pre-procedural 3-D MRI to be overlaid on intraprocedural 2-D fluoroscopy. This study describes our initial experience with the MR overlay technique in the angiography suite during pediatric percutaneous extremity bone biopsies of lesions visible on MRI but not on CT or fluoroscopy and demonstrates its utility in relevant clinical cases.

Contrast-enhanced voiding urosonography (ceVUS) with the intravesical administration of the ultrasound contrast agent Optison™ for vesicoureteral reflux detection in children: a prospective clinical trial.

BACKGROUND: Contrast-enhanced voiding urosonography (ceVUS) is widely used outside the United States to diagnose vesicoureteral reflux (VUR) in children and is highly sensitive while avoiding exposure to ionizing radiation. At the onset of this study, two ultrasound (US) contrast agents were available in the United States. Pediatric safety data for intravenous administration was published for one, Optison™. OBJECTIVE: This study aimed to evaluate the diagnostic performance and safety of ceVUS using Optison™ and compare its diagnostic efficacy with voiding cystourethrogram (VCUG) for VUR detection and grading in children. MATERIALS AND METHODS: The United States Food and Drug Administration and institutional Investigational New Drug authorizations were obtained to conduct a prospective comparative study of ceVUS with Optison™ and VCUG. CeVUS was performed with intravesical administration of 0.2% Optison™/normal saline solution. A standard VCUG followed. Safety assessment included physical examination, and heart rate, pulse oximetry and adverse reactions monitoring before, during and immediately after the examinations. A follow-up questionnaire was completed by telephone 48-h after the studies. RESULTS: Sixty-two pelviureteric units were studied in 30 patients with a mean age of 3.5 years (range: 0.1-17 years) including 21 girls and 9 boys. No severe adverse events occurred. All patients had normal heart rate and blood oxygenation saturation prior to, during and after the studies. At the 48-h follow-up, one patient (3.3%) reported transient dysuria. Taking the VCUG as the reference standard, ceVUS had a sensitivity of 91.7% (95%; confidence interval [CI]: 61.5%-99.8%) and specificity of 98% (95%; CI: 89.4%-99.9%). The concordance between ceVUS and VCUG for VUR detection and grading was 84.3% and 81.8%, respectively. VUR grades were discrepant in 4/11 refluxing pelviureteric units, with VCUG upgrading VUR in 2. CONCLUSION: Detection of VUR with Optison™ ceVUS was comparable to VCUG without exposure to ionizing radiation. CeVUS with Optison™ is a well-tolerated diagnostic procedure with a favorable safety profile.

Reduced-dose C-arm computed tomography applications at a pediatric institution.

BACKGROUND: Reduced-dose C-arm computed tomography (CT) uses flat-panel detectors to acquire real-time 3-D images in the interventional radiology suite to assist with anatomical localization and procedure planning. OBJECTIVE: To describe dose-reduction techniques for C-arm CT at a pediatric institution and to provide guidance for implementation. MATERIALS AND METHODS: We conducted a 5-year retrospective study on procedures using an institution-specific reduced-dose protocol: 5 or 8 s Dyna Rotation, 248/396 projection images/acquisition and 0.1-0.17 µGy/projection dose at the detector with 0.3/0.6/0.9-mm copper (Cu) filtration. We categorized cases by procedure type and average patient age and calculated C-arm CT and total dose area product (DAP). RESULTS: Two hundred twenty-two C-arm CT-guided procedures were performed with a dose-reduction protocol. The most common procedures were temporomandibular and sacroiliac joint injections (48.6%) and sclerotherapy (34.2%). C-arm CT was utilized in cases of difficult percutaneous access in less common applications such as cecostomy and gastrostomy placement, foreign body retrieval and thoracentesis. C-arm CT accounted for between 9.9% and 80.7% of the total procedural DAP. CONCLUSION: Dose-reducing techniques can preserve image quality for intervention while reducing radiation exposure to the child. This technology has multiple applications within pediatric interventional radiology and can be considered as an adjunctive imaging tool in a variety of procedures, particularly when percutaneous access is challenging despite routine fluoroscopic or ultrasound guidance.

Real-time fluoroscopic needle guidance in the interventional radiology suite using navigational software for percutaneous bone biopsies in children.

BACKGROUND: Navigational software provides real-time fluoroscopic needle guidance for percutaneous procedures in the Interventional Radiology (IR) suite. OBJECTIVE: We describe our experience with navigational software for pediatric percutaneous bone biopsies in the IR suite and compare technical success, diagnostic accuracy, radiation dose and procedure time with that of CT-guided biopsies. MATERIALS AND METHODS: Pediatric bone biopsies performed using navigational software (Syngo iGuide, Siemens Healthcare) from 2011 to 2016 were prospectively included and anatomically matched CT-guided bone biopsies from 2008 to 2016 were retrospectively reviewed with institutional review board approval. C-arm CT protocols used for navigational software-assisted cases included institution-developed low-dose (0.1/0.17 µGy/projection), regular-dose (0.36 µGy/projection), or a combination of low-dose/regular-dose protocols. Estimated effective radiation dose and procedure times were compared between software-assisted and CT-guided biopsies. RESULTS: Twenty-six patients (15 male; mean age: 10 years) underwent software-assisted biopsies (15 pelvic, 7 lumbar and 4 lower extremity) and 33 patients (13 male; mean age: 9 years) underwent CT-guided biopsies (22 pelvic, 7 lumbar and 4 lower extremity). Both modality biopsies resulted in a 100% technical success rate. Twenty-five of 26 (96%) software-assisted and 29/33 (88%) CT-guided biopsies were diagnostic. Overall, the effective radiation dose was significantly lower in software-assisted than CT-guided cases (3.0±3.4 vs. 6.6±7.7 mSv, P=0.02). The effective dose difference was most dramatic in software-assisted cases using low-dose C-arm CT (1.2±1.8 vs. 6.6±7.7 mSv, P=0.001) or combined low-dose/regular-dose C-arm CT (1.9±2.4 vs. 6.6±7.7 mSv, P=0.04), whereas effective dose was comparable in software-assisted cases using regular-dose C-arm CT (6.0±3.5 vs. 6.6±7.7 mSv, P=0.7). Mean procedure time was significantly lower for software-assisted cases (91±54 vs. 141±68 min, P=0.005). CONCLUSION: In our experience, navigational software technology in the IR suite is a promising alternative to CT guidance for pediatric bone biopsies providing comparable technical success and diagnostic accuracy with lower radiation dose and procedure time, in addition to providing real-time fluoroscopic needle guidance.

Early experience with X-ray magnetic resonance fusion for low-flow vascular malformations in the pediatric interventional radiology suite.

This technical innovation describes our experience using an X-ray magnetic resonance fusion (XMRF) software program to overlay 3-D MR images on real-time fluoroscopic images during sclerotherapy procedures for vascular malformations at a large pediatric institution. Five cases have been selected to illustrate the application and various clinical utilities of XMRF during sclerotherapy procedures as well as the technical limitations of this technique. The cases demonstrate how to use XMRF in the interventional suite to derive additional information to improve therapeutic confidence with regards to the extent of lesion filling and to guide clinical management in terms of intraprocedural interventional measures.

An investigation of motion correction algorithms for pediatric spinal cord DTI in healthy subjects and patients with spinal cord injury.

Patient and physiological motion can cause artifacts in DTI of the spinal cord which can impact image quality and diffusion indices. The purpose of this investigation was to determine a reliable motion correction method for pediatric spinal cord DTI and show effects of motion correction on DTI parameters in healthy subjects and patients with spinal cord injury. Ten healthy subjects and ten subjects with spinal cord injury were scanned using a 3T scanner. Images were acquired with an inner field-of-view DTI sequence covering cervical spine levels C1 to C7. Images were corrected for motion using two types of transformation (rigid and affine) and three cost functions. Corrected images and transformations were examined qualitatively and quantitatively using in-house developed code. Fractional anisotropy (FA) and mean diffusivity (MD) indices were calculated and tested for statistical significance pre- and post- motion correction. Images corrected using rigid methods showed improvements in image quality, while affine methods frequently showed residual distortions in corrected images. Blinded evaluation of pre and post correction images showed significant improvement in cord homogeneity and edge conspicuity in corrected images (p<0.0001). The average FA changes were statistically significant (p<0.0001) in the spinal cord injury group, while healthy subjects showed less FA change and were not significant. In both healthy subjects and subjects with spinal cord injury, quantitative and qualitative analysis showed the rigid scaled-least-squares registration technique to be the most reliable and effective in improving image quality.