Browsing by Author "Kralik, Stephen F."
Now showing 1 - 10 of 12
Results Per Page
Sort Options
Item children: differentiation using diffusion-weighted magnetic resonance imaging(Elsevier, 2017) Kralik, Stephen F.; Haider, Kathryn M.; Lobo, Remy R.; Supakul, Nucharin; Calloni, Sonia F.; Soares, Bruno P.; Radiology and Imaging Sciences, School of MedicinePurpose To evaluate differences in magnetic resonance imaging (MRI) appearance between infantile hemangiomas and rhabdomyosarcomas of the orbit in pediatric patients using diffusion-weighted imaging. Methods A multicenter retrospective review of MRIs of pediatric patients with infantile hemangiomas and rhabdomyosarcomas of the orbit was performed. MRI examinations from a total of 21 patients with infantile hemangiomas and 12 patients with rhabdomyosarcomas of the orbit were independently reviewed by two subspecialty board-certified neuroradiologists masked to the diagnosis. A freehand region of interest was placed in the mass to obtain the mean apparent diffusion coefficient (ADC) value of the mass as well as within the medulla to obtain a ratio of the ADC mass to the medulla. A t test was used to compare mean ADC and ADC ratios between the two groups. Receiver operating characteristic analysis was performed to determine ADC value and ADC ratio thresholds for differentiation of infantile hemangioma and rhabdomyosarcoma. Results There was a statistically significant difference in the mean ADC value of infantile hemangiomas compared to rhabdomyosarcomas (1527 × 10−6 mm2/s vs 782 × 10−6 mm2/s; P = 0.0001) and the ADC ratio of the lesion to the medulla (1.77 vs 0.92; P = 0.0001). An ADC threshold of <1159 × 10−6 mm2/sec and an ADC ratio of <1.38 differentiated rhabdomyosarcoma from infantile hemangioma (sensitivity 100% and 100%; specificity 100% and 100%) with area under the curve of 1.0 and 1.0, respectively. Conclusions In conjunction with conventional MRI sequences, ADC values obtained from diffusion-weighted MRI are useful to differentiate orbital infantile hemangiomas from rhabdomyosarcomas in pediatric patients.Item Comparison of multi-shot and single shot echo-planar diffusion tensor techniques for the optic pathway in patients with neurofibromatosis type 1(Springer, 2019-04) Ho, Chang Y.; Deardorff, Rachael; Kralik, Stephen F.; West, John D.; Wu, Yu-Chien; Shih, Chie-Schin; Radiology and Imaging Sciences, School of MedicinePurpose Diffusion tensor imaging (DTI) may be helpful in assessing optic pathway integrity as a marker for treatment in neurofibromatosis type 1 (NF1) patients with optic gliomas (OG). However, susceptibility artifacts are common in typical single-shot echo planar imaging (ssDTI). A readout-segmented multi-shot EPI technique (rsDTI) was utilized to minimize susceptibility distortions of the skull base and improve quantitative metrics. Methods Healthy controls, children with NF1 without OG, and NF1 with OG ± visual symptoms were included. All subjects were scanned with both rsDTI and ssDTI sequences sequentially. Diffusion metrics and deterministic fiber tracking were calculated. Tract count, volume, and length were also compared by a two-factor mixed ANOVA. Results Five healthy controls, 7 NF1 children without OG, and 12 NF1 children with OG were imaged. Six OG patients had visual symptoms. Four subjects had no detectable optic pathway fibers on ssDTI due to susceptibility, for which rsDTI was able to delineate. Tract count (p < 0.001), tract volume (p < 0.001), and FA (P < 0.001) were significantly higher for rsDTI versus ssDTI for all subjects. MD (p < 0.001) and RD (p < 0.001) were significantly lower for rsDTI vs ssDTI. Finally, MD, AD, and RD had a significantly lower difference in NF1 children with visual symptoms compared to NF1 children without visual symptoms only on ssDTI scans. Conclusion DTI with readout-segmented multi-shot EPI technique can better visualize the optic pathway and allow more confident measurements of anisotropy in NF1 patients. This is shown by a significant increase in FA, tract count, and volume with rsDTI versus ssDTI.Item Contrast Leakage Patterns from Dynamic Susceptibility Contrast Perfusion MRI in the Grading of Primary Pediatric Brain Tumors(2016) Ho, Chang Y.; Cardinal, Jeremy S.; Kamer, Aaron P.; Lin, Chen; Kralik, Stephen F.; Department of Radiology and Imaging Sciences, IU School of MedicineBACKGROUND AND PURPOSE: The pattern of contrast leakage from DSC tissue signal intensity time curves have shown utility in distinguishing adult brain neoplasms, but has limited description in the literature for pediatric brain tumors. The purpose of this study is to evaluate the utility of grading pediatric brain tumors with this technique. MATERIALS AND METHODS: A retrospective review of tissue signal-intensity time curves from 63 pediatric brain tumors with preoperative DSC perfusion MR imaging was performed independently by 2 neuroradiologists. Tissue signal-intensity time curves were generated from ROIs placed in the highest perceived tumor relative CBV. The postbolus portion of the curve was independently classified as returning to baseline, continuing above baseline (T1-dominant contrast leakage), or failing to return to baseline (T2*-dominant contrast leakage). Interobserver agreement of curve classification was evaluated by using the Cohen κ. A consensus classification of curve type was obtained in discrepant cases, and the consensus classification was compared with tumor histology and World Health Organization grade. RESULTS: Tissue signal-intensity time curve classification concordance was 0.69 (95% CI, 0.54–0.84) overall and 0.79 (95% CI, 0.59–0.91) for a T1-dominant contrast leakage pattern. Twenty-five of 25 tumors with consensus T1-dominant contrast leakage were low-grade (positive predictive value, 1.0; 95% CI, 0.83–1.00). By comparison, tumors with consensus T2*-dominant contrast leakage or return to baseline were predominantly high-grade (10/15 and 15/23, respectively) with a high negative predictive value (1.0; 95% CI, 0.83–1.0). For pilomyxoid or pilocytic astrocytomas, a T1-dominant leak demonstrated high sensitivity (0.91; 95% CI, 0.70–0.98) and specificity (0.90, 95% CI, 0.75–0.97). CONCLUSIONS: There was good interobserver agreement in the classification of DSC perfusion tissue signal-intensity time curves for pediatric brain tumors, particularly for T1-dominant leakage. Among patients with pediatric brain tumors, a T1-dominant leakage pattern is highly specific for a low-grade tumor and demonstrates high sensitivity and specificity for pilocytic or pilomyxoid astrocytomas.Item Differentiation of pilocytic and pilomyxoid astrocytomas using dynamic susceptibility contrast perfusion and diffusion weighted imaging(Springer, 2020-10) Ho, Chang Y.; Supakul, Nucharin; Patel, Parth U.; Seit, Vetana; Groswald, Michael; Cardinal, Jeremy; Lin, Chen; Kralik, Stephen F.; Radiology and Imaging Sciences, School of MedicinePurpose Pilocytic (PA) and pilomyxoid astrocytomas (PMA) are related low-grade tumors which occur predominantly in children. PMAs have a predilection for a supratentorial location in younger children with worse outcomes. However, the two have similar imaging characteristics. Quantitative MR sequences such as dynamic susceptibility contrast (DSC) perfusion and diffusion (DWI) were assessed for significant differences between the two tumor types and locations. Methods A retrospective search for MRI with DSC and DWI on pathology-proven cases of PMA and PA in children was performed. Tumors were manually segmented on anatomic images registered to rCBV, K2, and ADC maps. Tumors were categorized as PA or PMA, with subclassification of supratentorial and infratentorial locations. Mean values were obtained for tumor groups and locations compared with Student’s t test for significant differences with post hoc correction for multiple comparisons. ROC analysis for significant t test values was performed. Histogram evaluation was also performed. Results A total of 49 patients met inclusion criteria. This included 30 patients with infratentorial PA, 8 with supratentorial PA, 6 with supratentorial PMA, and 5 with infratentorial PMA. Mean analysis showed significantly increased rCBV for infratentorial PMA (2.39 ± 1.1) vs PA (1.39 ± 0.16, p = 0.0006). ROC analysis for infratentorial PA vs PMA yielded AUC = 0.87 (p < 0.001). Histogram analysis also demonstrated a higher ADC peak location for PMA (1.8 ± 0.2) vs PA (1.56 ± 0.28). Conclusion PMA has a significantly higher rCBV than PA in the infratentorial space. DSC perfusion and diffusion MR imaging may be helpful to distinguish between the two tumor types in this location.Item Diffusion, Perfusion, and Histopathologic Characteristics of Desmoplastic Infantile Ganglioglioma.(EduRad Publishing, 2016-07) Ho, Chang Y.; Gener, Melissa; Bonnin, Jose; Kralik, Stephen F.; Department of Radiology and Imaging Sciences, IU School of MedicineWe present a case series of a rare tumor, the desmoplastic infantile ganglioglioma (DIG) with MRI diffusion and perfusion imaging quantification as well as histopathologic characterization. Four cases with pathologically-proven DIG had diffusion weighted imaging (DWI) and two of the four had dynamic susceptibility contrast imaging. All four tumors demonstrate DWI findings compatible with low-grade pediatric tumors. For the two cases with perfusion imaging, a higher relative cerebral blood volume was associated with higher proliferation index on histopathology for one of the cases. Our results are discussed in conjunction with a literature review.Item Image segmentation of plexiform neurofibromas from a deep neural network using multiple b-value diffusion data(Nature Publishing Group, 2020-10-20) Ho, Chang Y.; Kindler, John M.; Persohn, Scott; Kralik, Stephen F.; Robertson, Kent A.; Territo, Paul R.; Radiology and Imaging Sciences, School of MedicineWe assessed the accuracy of semi-automated tumor volume maps of plexiform neurofibroma (PN) generated by a deep neural network, compared to manual segmentation using diffusion weighted imaging (DWI) data. NF1 Patients were recruited from a phase II clinical trial for the treatment of PN. Multiple b-value DWI was imaged over the largest PN. All DWI datasets were registered and intensity normalized prior to segmentation with a multi-spectral neural network classifier (MSNN). Manual volumes of PN were performed on 3D-T2 images registered to diffusion images and compared to MSNN volumes with the Sørensen-Dice coefficient. Intravoxel incoherent motion (IVIM) parameters were calculated from resulting volumes. 35 MRI scans were included from 14 subjects. Sørensen-Dice coefficient between the semi-automated and manual segmentation was 0.77 ± 0.016. Perfusion fraction (f) was significantly higher for tumor versus normal tissue (0.47 ± 0.42 vs. 0.30 ± 0.22, p = 0.02), similarly, true diffusion (D) was significantly higher for PN tumor versus normal (0.0018 ± 0.0003 vs. 0.0012 ± 0.0002, p < 0.0001). By contrast, the pseudodiffusion coefficient (D*) was significantly lower for PN tumor versus normal (0.024 ± 0.01 vs. 0.031 ± 0.005, p < 0.0001). Volumes generated by a neural network from multiple diffusion data on PNs demonstrated good correlation with manual volumes. IVIM analysis of multiple b-value diffusion data demonstrates significant differences between PN and normal tissue.Item Intracranial chordoma presenting as acute hemorrhage in a child: Case report and literature review(Wolters Kluwer, 2015-04-20) Moore, Kenneth A.; Bohnstedt, Bradley N.; Shah, Sanket U.; Abdulkader, Marwah M.; Bonnin, Jose M.; Ackerman, Laurie L.; Shaikh, Kashif; Kralik, Stephen F.; Shah, Mitesh V.; Department of Neurological Surgery, IU School of MedicineBACKGROUND: Chordomas are rare, slow-growing malignant neoplasms derived from remnants of the embryological notochord. Pediatric cases comprise only 5% of all chordomas, but more than half of the reported pediatric chordomas are intracranial. For patients of all ages, intracranial chordomas typically present with symptoms such as headaches and progressive neurological deficits occurring over several weeks to many years as they compress or invade local structures. There are only reports of these tumors presenting acutely with intracranial hemorrhage in adult patients. CASE DESCRIPTION: A 10-year-old boy presented with acute onset of headache, emesis, and diplopia. Head computed tomography and magnetic resonance imaging of brain were suspicious for a hemorrhagic mass located in the left petroclival region, compressing the ventral pons. The mass was surgically resected and demonstrated acute intratumoral hemorrhage. Pathologic examination was consistent with chordoma. CONCLUSION: There are few previous reports of petroclival chordomas causing acute intracranial hemorrhage. To the authors' knowledge, this is the first case of a petroclival chordoma presenting as acute intracranial hemorrhage in a pediatric patient. Although uncommon, it is important to consider chordoma when evaluating a patient of any age presenting with a hemorrhagic lesion of the clivus.Item Magnetic resonance imaging findings in children with spasmus nutans(Elsevier, 2017-04) Bowen, Meredith; Peragallo, Jason; Kralik, Stephen F.; Poretti, Andrea; Huisman, Thierry A. G. M.; Soares, Bruno P.; Department of Radiology and Imaging Sciences, IU School of MedicineBackground Spasmus nutans (SN) is a rare pediatric ophthalmologic syndrome characterized by nystagmus, head bobbing, and abnormal head positioning. Historically, SN has been associated with underlying optic pathway gliomas (OPG); however, evidence of this association is based primarily on a small number of isolated case reports. Prior retrospective analyses have found the rate of OPG to be <2%, but these studies only intermittently used neuroimaging with computed tomography, which has limited sensitivity for detection of small lesions in the optic pathway. The purpose of this study was to investigate the association of SN with intracranial abnormalities, particularly OPG, using magnetic resonance imaging of the brain and orbits. Methods Neuroradiology databases at three institutions spanning January 2010 to May 2016 were queried for examinations ordered for evaluation of SN; MRI examinations of the brain and/or orbits were included and evaluated for OPG and other structural abnormalities. Medical records were reviewed to confirm a diagnosis of SN, presence of other underlying neurological disease, or preexisting diagnoses. Results A total of 40 patients with eligible MRI examinations were identified. None had optic nerve pathway gliomas. Two children had optic nerve hypoplasia; no other patients had optic pathway abnormalities. None had intracranial or orbital masses. MRI examinations were normal in 25 patients. Conclusions This series represents the largest collection of MRI examinations for SN in the literature to date and shows no association between OPG and SN. In children presenting with SN but no other findings suggesting OPG or neurological abnormalities, neuroimaging may not be required.Item Radiation Induced Cerebral Microbleeds in Pediatric Patients with Brain Tumors Treated with Proton Radiotherapy(Elsevier, 2018) Kralik, Stephen F.; Mereniuk, Todd R.; Grignon, Laurent; Shih, Chie-Schin; Ho, Chang Y.; Finke, Whitney; Coleman, Peter W.; Watson, Gordon A.; Buchsbaum, Jeffrey; Radiology and Imaging Sciences, School of MedicinePurpose Proton beam radiotherapy (PBT) has been increasingly utilized to treat pediatric brain tumors, however, limited information exists regarding radiation induced cerebral microbleeds (CMBs) among these patients. The purpose was to evaluate the incidence, risk factors, and imaging appearance of CMBs in pediatric patients with brain tumors treated with PBT. Methods A retrospective study was performed on 100 pediatric patients with primary brain tumors treated with PBT. CMBs were diagnosed by examining serial MRIs including susceptibility-weighted imaging. Radiation therapy plans were analyzed to determine doses to individual CMBs. Clinical records were used to determine risk factors associated with the development of CMBs in these patients. Results The mean age at time of PBT was 8.1 years. The median follow-up duration was 57 months. The median time to development of CMBs was 8 months (mean 11 months; range 3-28 months). The percentage of patients with CMBs was 43%, 66%, 80%, 81%, 83%, and 81% at 1-year, 2-years, 3-years, 4-year, 5-years, and greater than 5 years from completion of proton radiotherapy. The majority (87%) of CMBs were found in areas of brain exposed to ≥ 30 Gy. Risk factors included maximum radiotherapy dose (P=0.001), percentage and volume of brain exposed to ≥ 30 Gy (P=0.0004; P=0.0005), and patient age at time of PBT (P=0.0004). Chemotherapy was not a significant risk factor (P=0.35). No CMBs required surgical intervention. Conclusion CMBs develop in a high percentage of pediatric patients with brain tumors treated with proton radiotherapy within the first few years following treatment. Significant risk factors for development of CMBs include younger age at time of PBT, higher maximum radiotherapy dose, and higher percentage and volume of brain exposed to ≥ 30 Gy. These findings demonstrate similarities with CMBs that develop in pediatric brain tumor patients treated with photon radiotherapy.Item Radiation-Induced Large Vessel Cerebral Vasculopathy in Pediatric Patients with Brain Tumors Treated with Proton Radiotherapy(Elsevier, 2017) Kralik, Stephen F.; Shih, Chie-schin; Ho, Chang Y.; Finke, Whitney; Buchsbaum, Jeffrey; Watson, Gordon A.; Department of Radiology and Imaging Sciences, School of MedicinePurpose The purpose of this research is to evaluate the incidence, time to development, imaging patterns, risk factors, and clinical significance of large vessel cerebral vasculopathy in pediatric patients with brain tumors treated with proton radiotherapy. Materials and Methods A retrospective study was performed on 75 consecutive pediatric patients with primary brain tumors treated with proton radiotherapy. Radiation-induced large vessel cerebral vasculopathy (RLVCV) was defined as intracranial large vessel arterial stenosis or occlusion confirmed on MRA, CTA, and/or catheter angiography within an anatomic region with previous exposure to proton beam therapy and not present prior to radiotherapy. Clinical records were used to determine the incidence, timing, radiation dose to the large vessels, and clinical significance associated with the development of large vessel vasculopathy in these patients. Results RLVCV was present in 5/75 (6.7%) of patients and included tumor pathologies of craniopharyngioma (2), ATRT (1), medulloblastoma (1), and anaplastic astrocytoma (1). Median time from completion of radiotherapy to development was 1.5 years (mean 3.0 years; range 1.0-7.5 years). Neither mean age at time of radiotherapy (5.1 years) nor mean radiotherapy dose to the large vessels (54.5 Gy) were statistically significant risk factors. Four of the five patients with RLVCV presented with acute stroke, and demonstrated MRI evidence of acute infarcts in the expected vascular distributions. Angiography studies demonstrated collateral vessel formation in only two of the patients with RLVCV. No patients demonstrated acute hemorrhage or aneurysm. Two patients were treated with pial synangiomatosis surgery. Conclusion RLVCV can occur in pediatric patients with brain tumors treated with proton radiotherapy. Further studies are necessary to determine potential risk factors for large vessel vasculopathy with proton radiotherapy in comparison with conventional photon radiotherapy.