A case report of spinal toxocariasis with extensive tumor-like involvement.

BACKGROUND: Toxocariasis is a common parasitic infection worldwide. Although it can present as several clinical syndromes, neurological manifestation is rare. Only a few reports are available on spinal cord involvement of toxocariasis. We report a case that presented with gait disturbance due to progressive lower limb spasticity. The patient had had visceral toxocariasis infection 8 years before. A spine magnetic resonance image (MRI) showed syringomyelia along the entire thoracic cord with small nodular enhancing lesions in the mid-portion of the syrinx, which led to the suspicion of ependymoma. Surgical mass removal was performed. However, histopathological examination of the mass did not show any malignant cells; instead, there were numerous axonal retraction balls with an eosinophilic granular body-like appearance. The serum antibody titer against toxocariasis was borderline high. Taken together, these observations led to a diagnosis of Toxocara infection, and the patient was treated with albendazole. CONCLUSION: To the best of our knowledge, this is the first case report of tumor-like spinal toxocariasis involving extensive lesions. A solid enhancing mass with accompanied syrinx and hemorrhage might be a Toxocara infection. It can easily be diagnosed with serologic tests and simply be treated with oral albendazole if suspected.

Evaluation of frequency-selective non-linear blending technique on brain CT in postoperative children with Moyamoya disease.

OBJECTIVE: To evaluate whether a frequency-selective non-linear blending (BC) technique can improve tissue contrast and infarct detection on non-enhanced brain CT (NECT) in postoperative Moyamoya (MMD) patients. MATERIALS AND METHODS: From January 2010 to December 2017, 33 children (13boys and 20girls; mean age 9.1±3.4 years) with MMD postoperatively underwent NECT followed by diffusion MRI. We compared the contrast-to-noise ratio (CNR) between gray matter (GM) and white matter (WM) in NECT and BC images and the CNR between the infarct lesion and adjacent normal-appearing brain in NECT and BC images using a paired t-test. We assessed image noise, GM-WM differentiation, artifacts, and overall quality using a Wilcoxon signed rank test. A McNemar two-tailed test was conducted to compare the diagnostic accuracy of infarct detection. RESULTS: The CNR between GM and WM and the CNR of the infarct was better in BC images than in NECT images (3.9±1.0 vs. 1.8±0.6, P<0.001 and 3.6±0.3 vs. 1.9±0.2, P<0.001), with no difference in overall image quality observed. The sensitivity and specificity of infarct detection were 55.0% and 76.9% using NECT, and 70.0% and 69.2% using BC technique. The diagnostic accuracy of NECT and BC technique was 63.6% (21/33) and 69.7% (23/33), respectively. CONCLUSION: This study showed that the BC technique improved CNR and maintained image quality. This technique may also be used to identify ischemic brain changes in postoperative MMD patients by improving the CNR of the infarct lesion.

Autonomic Dysfunction is Associated with Increased Cardiometabolic Risk in Patients with Childhood-Onset Craniopharyngioma.

Patients with craniopharyngioma are susceptible to autonomic dysfunction as a result of hypothalamic damage. We evaluated indices of heart rate variability (HRV) in patients with childhood-onset craniopharyngioma to investigate autonomic function and its relationship with components of the metabolic syndrome (MetS). This cross-sectional, case-only study included 53 patients (10-30 years of age). We measured the standard deviation of all normal R-R intervals (SDNN) and total power indicating overall HRV, the root-mean square of the difference of successive R-R intervals (RMSSD) and high frequency indicating parasympathetic modulation, and low frequency. These indices were compared according to the presence of the MetS. During the mean 10.8 years of follow-up, 25% of patients were diagnosed with the MetS. Patients with the MetS showed significantly lower levels of SDNN (29.0 vs. 40.6 ms), total power (416.1 vs. 1129.6 ms2), RMSSD (20.1 vs. 34.5 ms), high frequency (94.7 vs. 338.5 ms2), and low frequency (94.5 vs. 289.4 ms2) than those without (p <0.05, for all). Individual components of the MetS including insulin resistance, serum triglycerides levels, and systolic blood pressure were inversely associated with SDNN, total power, RMSSD and high frequency. Higher overall variability and parasympathetic modulation were related to decreased odds ratios for having the MetS (OR 0.91, p=0.029 for SDNN; OR 0.91, p=0.032 for total power). In conclusion, autonomic dysfunction, as evidenced by reduced HRV indices, is associated with increased cardiometabolic risk in patients with childhood-onset craniopharyngioma.

Application of T1-weighted BLADE sequence to abdominal magnetic resonance imaging of young children: a comparison with turbo spin echo sequence.

BACKGROUND: The image quality of abdominal magnetic resonance imaging (MRI) in children who cannot hold their breath has been severely impaired by motion artifacts. PURPOSE: To evaluate the usefulness of T1-weighted (T1W) BLADE MRI for axial abdominal imaging in children who cannot hold their breath. MATERIAL AND METHODS: Two different BLADE sequences, with and without an inversion recovery (IR-BLADE), were compared to conventional turbo-spin echo (TSE) with a high number of excitations in 18 consecutive patients who cannot hold their breath. Overall image quality, motion artifact, radial artifact, hepatic vessel sharpness, renal corticomedullary differentiation, and lesion conspicuity were retrospectively assessed by two radiologists, using 4- or 5-point scoring systems. Signal variations of each sequence were measured for a quantitative comparison. The acquisition times of the three sequences were compared. RESULTS: IR-BLADE and BLADE showed significantly improved overall image quality and reduced motion artifact compared with TSE. IR-BLADE showed significantly better hepatic vessel sharpness and corticomedullary differentiation compared to both BLADE and TSE. Radial artifacts were only observed on IR-BLADE and BLADE. In nine patients with lesions, there were no significant differences in lesion conspicuity among three sequences. Compared to TSE, both IR-BLADE and BLADE showed decreased signal variations in the liver and muscle, and an increased signal variation through air. The mean acquisition times for IR-BLADE, BLADE, and TSE were comparable. CONCLUSION: Compared to the TSE sequence, T1W IR-BLADE for pediatric abdominal MRI resulted in improved image quality, tissue contrast with a diminished respiratory motion artifact, and a comparable acquisition time.

Diagnostic Role of Renal Doppler Ultrasound and Plasma Renin Activity as Screening Tools for Renovascular Hypertension in Children.

OBJECTIVES: The diagnostic role of an ultrasound (US) and plasma renin activity (PRA) combination is unknown, despite the usefulness of Doppler US as a screening tool for renovascular hypertension (RVHT). The purpose of this study was to evaluate the diagnostic usefulness of US for RVHT in children stratified according to PRA. METHODS: We identified 336 children who underwent renal Doppler US examinations for hypertension and divided them into a high-renin group (n = 177) and a normal-renin group (n = 159) based on PRA and stratified them by age. The Doppler US findings were retrospectively reviewed, and computed tomographic angiography (CTA) for the same children was used as the reference standard. RESULTS: In the high-renin group, 36 patients had positive Doppler US findings that were confirmed by CTA in 32 cases. The sensitivity and specificity values for Doppler US in the high-renin group were 84.2% and 93.6%, respectively. In the normal-renin group, 10 patients had positive Doppler US findings; these positive findings were confirmed by CTA in 9 cases. The sensitivity and specificity values for US in the normal-renin group were 100.0% and 100.0%. There were anatomic variations (n = 3) and segmental artery stenosis (n = 2) among the cases with false-negative US findings, which were confirmed by CTA. CONCLUSIONS: If patients have high PRA, a Doppler US examination should be performed with caution to avoid false-negative detection. If patients have normal PRA, renal Doppler US might be adequate for diagnosis of RVHT to avoid unnecessary CTA.

Gallbladder wall oedema and ascites are independent predictors of progression to hepatic veno-occlusive disease for children with hematopoietic stem cell transplantation.

OBJECTIVES: To evaluate the predictive value of ultrasonography in children with clinically suspicious hepatic veno-occlusive disease (VOD) after hematopoietic stem cell transplantation (HSCT). METHODS: Among 216 children who underwent HSCT, 70 also underwent colour Doppler ultrasonography. Of these, 59 had only one sign/symptom, which did not fulfil the diagnostic criteria (clinical suspicion of VOD) at that time. VOD was confirmed in 20 patients (VOD group), while 39 had other conditions (non-VOD group). The following findings were reviewed and compared between groups: left portal vein (peak velocity, direction), left hepatic artery (peak-systolic/end-diastolic velocities, resistive index), middle hepatic vein (peak velocity, phasicity), hepatomegaly, splenomegaly, gallbladder wall thickness, and ascites. RESULTS: The VOD group showed significantly higher reversed flow in portal vein (P = 0.011), peak systolic velocity of left hepatic artery (P = 0.028), monophasicity of middle hepatic vein (P = 0.015), hepatomegaly (P = 0.001), gallbladder wall thickness (P < 0.001), and ascites (P < 0.001). Multivariate regression revealed that gallbladder wall thickness and ascites (odds ratio = 35.370, 56.393) were associated with VOD. CONCLUSIONS: The presence of reversed flow in portal vein, increased peak systolic velocity of hepatic artery, monophasicity of hepatic vein, hepatomegaly, gallbladder wall thickness, and ascites were significantly associated with progression to VOD in children with clinically suspicious VOD after HSCT. KEY POINTS: • Ultrasonography with Doppler can help predict progression to VOD. • Gallbladder wall oedema and ascites are the independent predictors of progression to VOD.

Three-Dimensional Radial VIBE Sequence for Contrast-Enhanced Brain Imaging: An Alternative for Reducing Motion Artifacts in Restless Children.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of radially sampled 3D fat-suppressed T1-weighted gradient-echo sequences (radial volumetric interpolated breath-hold examination [radial VIBE]) for contrast-enhanced brain MRI of children through comparison with a magnetization-prepared rapid-acquisition gradient-echo (MP-RAGE) sequence. MATERIALS AND METHODS: Sixty-five consecutive contrast-enhanced brain MRI examinations performed with axial MP-RAGE and radial VIBE sequences were included. For quantitative analysis, coefficients of variation of gray matter and white matter and CSF and relative contrast between tissue types (gray matter and white matter, gray matter and CSF, and white matter and CSF) for each sequence were calculated. For qualitative assessment, motion, pulsation artifacts, overall image quality, and lesion conspicuity were retrospectively scored on a 5-point scale. Quantitative and qualitative subgroup analyses were performed for patients with serious motion artifacts. RESULTS: Images obtained with the radial VIBE sequence had fewer motion and pulsation artifacts than those obtained with the MP-RAGE sequence (MP-RAGE vs radial VIBE motion score, 3.57 ± 1.00 vs 4.52 ± 0.51; pulsation score, 3.57 ± 0.60 vs 4.91 ± 0.21; all p < 0.001). Among 25 images with serious motion artifacts, radial VIBE images had significantly higher scores for all qualitative parameters, including overall image quality, than did MP-RAGE images (overall image quality for MP-RAGE vs radial VIBE, 2.63 ± 0.82 vs 3.42 ± 0.55, p < 0.001). CONCLUSION: The study showed that a radial fat-suppressed T1-weighted gradient-echo sequence is a viable alternative to conventional cartesian acquisition for contrast-enhanced brain imaging of restless children.

Comparison of DWI Methods in the Pediatric Brain: PROPELLER Turbo Spin-Echo Imaging Versus Readout-Segmented Echo-Planar Imaging Versus Single-Shot Echo-Planar Imaging.

OBJECTIVE: The purpose of this study is to compare DWI for pediatric brain evaluation using single-shot echo-planar imaging (EPI), periodically rotated overlapping parallel lines with enhanced reconstruction (Blade), and readout-segmented EPI (Resolve). MATERIALS AND METHODS: Blade, Resolve, and single-shot EPI were performed for 27 pediatric patients (median age, 9 years), and three datasets were independently reviewed by two radiologists. Qualitative analyses were performed for perceptive coarseness, image distortion, susceptibility-related changes, motion artifacts, and lesion conspicuity using a 5-point Likert scale. Quantitative analyses were conducted for spatial distortion and signal uniformity of each sequence. RESULTS: Mean scores were 2.13, 3.17, and 3.76 for perceptive coarseness; 4.85, 3.96, and 2.19 for image distortion; 4.76, 3.96, and 2.30 for susceptibility-related change; 4.96, 3.83, and 4.69 for motion artifacts; and 2.71, 3.75, and 1.92 for lesion conspicuity, for Blade, Resolve, and single-shot EPI, respectively. Blade and Resolve showed better quality than did single-shot EPI for image distortion, susceptibility-related changes, and lesion conspicuity. Blade showed less image distortion, fewer susceptibility-related changes, and fewer motion artifacts than did Resolve, whereas lesion conspicuity was better with Resolve. Blade showed increased signal variation compared with Resolve and single-shot EPI (coefficients of variation were 0.10, 0.08, and 0.05 for lateral ventricle; 0.13, 0.09, and 0.05 for centrum semiovale; and 0.16, 0.09, and 0.06 for pons in Blade, Resolve, and single-shot EPI, respectively). CONCLUSION: DWI with Resolve or Blade yields better quality regarding distortion, susceptibility-related changes, and lesion conspicuity, compared with single-shot EPI. Blade is less susceptible to motion artifacts than is Resolve, whereas Resolve yields less noise and better lesion conspicuity than does Blade.

Benign extracerebral fluid collection complicated by subdural hematoma and fluid collection: clinical characteristics and management.

INTRODUCTION: Benign extracerebral fluid collection (bECFC) can be complicated by subdural hematoma (SDH) or subdural fluid collection (SDFC). The etiology, natural history, and management strategy for SDH/SDFC in bECFC are not fully understood. We retrospectively reviewed the cases of bECFC patients complicated with SDH/SDFC and tried (1) to confirm the fact that bECFC children are vulnerable to SDH/SDFC, (2) to investigate the clinical significance of 'trauma history' witnessed by a caregiver, and (3) to determine optimal management for them. METHOD: Among 213 bECFC patients identified from January 2000 to August 2015, 20 patients (male:female = 14:6; median age, 6.5 months; range 1-16 months) complicated by SDH/SDFC documented with brain imaging were evaluated for their clinical manifestations, radiologic features, and management outcomes. The median follow-up period was 9.5 months. They were divided into two groups (traumatic group versus non-traumatic group) according to whether objective radiologic evidence of head injury was present or not, and the two groups were analyzed for any clinical differences between them. We also evaluated the clinical significance of witnessed traumatic events by caregivers as an additional independent variable in the analysis. RESULTS: The incidence of SDH/SDFC in bECFC patients was 9.4% (20/213) in our data. In a comparative analysis, the traumatic group is more likely to have 'acute' stage SDH, whereas the non-traumatic group is more likely to have 'chronic' stage SDH. The trauma history witnessed by caregivers did not show clinical significance in the data analysis when included as an independent variable. The prognosis of SDH/SDFC in bECFC patients was favorable without surgery in most of patients regardless of whether the patient has evidence of head trauma or not. CONCLUSION: Benign ECFC is vulnerable to SDH/SDFC development. For the bECFC patients complicated by SDH/SDFC, the trauma history witnessed by a caregiver did not show any clinical significance. A 'wait and watch' strategy is sufficient for the management of SDH/SDFC in bECFC patients.

Unenhanced 320-row multidetector computed tomography of the brain in children: comparison of image quality and radiation dose among wide-volume, one-shot volume, and helical scan modes.

BACKGROUND: The 320-row multidetector computed tomography (CT) scanner has multiple scan modes, including volumetric modes. OBJECTIVE: To compare the image quality and radiation dose of 320-row CT in three acquisition modes - helical, one-shot volume, and wide-volume scan - at pediatric brain imaging. MATERIALS AND METHODS: Fifty-seven children underwent unenhanced brain CT using one of three scan modes (helical scan, n=21; one-shot volume scan, n=17; wide-volume scan, n=19). For qualitative analysis, two reviewers evaluated overall image quality and image noise using a 5-point grading system. For quantitative analysis, signal-to-noise ratio, image noise and posterior fossa artifact index were calculated. To measure the radiation dose, adjusted CT dose index per unit volume (CTDIadj) and dose length product (DLP) were compared. RESULTS: Qualitatively, the wide-volume scan showed significantly less image noise than the helical scan (P=0.009), and less streak artifact than the one-shot volume scan (P=0.001). The helical mode showed significantly lower signal-to-noise ratio, with a higher image noise level compared with the one-shot volume and wide-volume modes (all P<0.05). The CTDIadj and DLP were significantly lower in the one-shot volume and wide-volume modes compared with those in the helical scan mode (all P<0.05). CONCLUSION: For pediatric unenhanced brain CT, both the wide-volume and one-shot volume scans reduced radiation dose compared to the helical scan mode, while the wide-volume scan mode showed fewer streak artifacts in the skull vertex and posterior fossa than the one-shot volume scan.

Radiologic evaluation of pulmonary injury following carmustine- and cyclophosphamide-based preparative regimen for autologous peripheral blood stem cell transplantation in children.

BACKGROUND: Toxicity of carmustine and cyclophosphamide can cause pulmonary injury after hematopoietic stem cell transplantation. OBJECTIVE: To evaluate the radiologic findings of pulmonary injuries following carmustine- and cyclophosphamide-based preparative regimens in children. MATERIALS AND METHODS: From 2010 to 2014, 35 children received carmustine- and cyclophosphamide-based preparative regimens. Fourteen of 35 children presented with symptoms and radiologic abnormalities. Eight of 14 children had no evidence of infection, cardiogenic edema, or other explainable causes. We retrospectively analyzed their chest radiographs and CT scans for ground-glass opacity, consolidation, septal thickening and pleural effusion. RESULTS: Major chest radiographic findings were bilateral diffuse ground-glass opacity (n=8) and septal thickening (n=7). CT findings were multifocal patchy (n=4) or inhomogeneously diffuse (n=4) ground-glass opacity, multifocal consolidations (n=7) and septal thickening (n=7). All of these lesions at CT were bilateral, but showed lower lobe predominance in 88, 100, and 63%, respectively. There was no central/peripheral or anterior/posterior predilection. Six children had small pleural effusions, which were bilateral in five children. CONCLUSION: Bilateral ground-glass opacity with or without consolidation, septal thickening and pleural effusion were common radiologic findings in pulmonary injury following carmustine- and cyclophosphamide-based preparative regimens.

Advanced virtual monochromatic reconstruction of dual-energy unenhanced brain computed tomography in children: comparison of image quality against standard mono-energetic images and conventional polychromatic computed tomography.

BACKGROUND: Advanced virtual monochromatic reconstruction from dual-energy brain CT has not been evaluated in children. OBJECTIVE: To determine the most effective advanced virtual monochromatic imaging energy level for maximizing pediatric brain parenchymal image quality in dual-energy unenhanced brain CT and to compare this technique with conventional monochromatic reconstruction and polychromatic scanning. MATERIALS AND METHODS: Using both conventional (Mono) and advanced monochromatic reconstruction (Mono+) techniques, we retrospectively reconstructed 13 virtual monochromatic imaging energy levels from 40 keV to 100 keV in 5-keV increments from dual-source, dual-energy unenhanced brain CT scans obtained in 23 children. We analyzed gray and white matter noise ratios, signal-to-noise ratios and contrast-to-noise ratio, and posterior fossa artifact. We chose the optimal mono-energetic levels and compared them with conventional CT. RESULTS: For Mono+maximum optima were observed at 60 keV, and minimum posterior fossa artifact at 70 keV. For Mono, optima were at 65-70 keV, with minimum posterior fossa artifact at 75 keV. Mono+ was superior to Mono and to polychromatic CT for image-quality measures. Subjective analysis rated Mono+superior to other image sets. CONCLUSION: Optimal virtual monochromatic imaging using Mono+ algorithm demonstrated better image quality for gray-white matter differentiation and reduction of the artifact in the posterior fossa.

Image quality and radiation dose of brain computed tomography in children: effects of decreasing tube voltage from 120 kVp to 80 kVp.

BACKGROUND: Computed tomography (CT) has generated public concern associated with radiation exposure, especially for children. Lowering the tube voltage is one strategy to reduce radiation dose. OBJECTIVE: To assess the image quality and radiation dose of non-enhanced brain CT scans acquired at 80 kilo-voltage peak (kVp) compared to those at 120 kVp in children. MATERIALS AND METHODS: Thirty children who had undergone both 80- and 120-kVp non-enhanced brain CT were enrolled. For quantitative analysis, the mean attenuation of white and gray matter, attenuation difference, noise, signal-to-noise ratio, contrast-to-noise ratio and posterior fossa artifact index were measured. For qualitative analysis, noise, gray-white matter differentiation, artifact and overall image quality were scored. Radiation doses were evaluated by CT dose index, dose-length product and effective dose. RESULTS: The mean attenuations of gray and white matter and contrast-to-noise ratio were significantly increased at 80 kVp, while parameters related to image noise, i.e. noise, signal-to-noise ratio and posterior fossa artifact index were higher at 80 kVp than at 120 kVp. In qualitative analysis, 80-kVp images showed improved gray-white differentiation but more artifacts compared to 120-kVp images. Subjective image noise and overall image quality scores were similar between the two scans. Radiation dose parameters were significantly lower at 80 kVp than at 120 kVp. CONCLUSION: In pediatric non-enhanced brain CT scans, a decrease in tube voltage from 120 kVp to 80 kVp resulted in improved gray-white matter contrast, comparable image quality and decreased radiation dose.

Image quality at synthetic brain magnetic resonance imaging in children.

BACKGROUND: The clinical application of the multi-echo, multi-delay technique of synthetic magnetic resonance imaging (MRI) generates multiple sequences in a single acquisition but has mainly been used in adults. OBJECTIVE: To evaluate the image quality of synthetic brain MR in children compared with that of conventional images. MATERIALS AND METHODS: Twenty-nine children (median age: 6 years, range: 0-16 years) underwent synthetic and conventional imaging. Synthetic (T2-weighted, T1-weighted and fluid-attenuated inversion recovery [FLAIR]) images with settings matching those of the conventional images were generated. The overall image quality, gray/white matter differentiation, lesion conspicuity and image degradations were rated on a 5-point scale. The relative contrasts were assessed quantitatively and acquisition times for the two imaging techniques were compared. RESULTS: Synthetic images were inferior due to more pronounced image degradations; however, there were no significant differences for T1- and T2-weighted images in children <2 years old. The quality of T1- and T2-weighted images were within the diagnostically acceptable range. FLAIR images showed greatly reduced quality. Gray/white matter differentiation was comparable or better in synthetic T1- and T2-weighted images, but poorer in FLAIR images. There was no effect on lesion conspicuity. Synthetic images had equal or greater relative contrast. Acquisition time was approximately two-thirds of that for conventional sequences. CONCLUSION: Synthetic T1- and T2-weighted images were diagnostically acceptable, but synthetic FLAIR images were not. Lesion conspicuity and gray/white matter differentiation were comparable to conventional MRI.

Comparison of Image Quality and Radiation Dose between High-Pitch Mode and Low-Pitch Mode Spiral Chest CT in Small Uncooperative Children: The Effect of Respiratory Rate.

OBJECTIVES: To compare image quality and radiation dose between high-pitch mode (HPM) and low-pitch mode (LPM) CT in young children. MATERIALS AND METHODS: Forty-seven children (mean age 35.6 months; range, 0-126 months) underwent 49 CT examinations in HPM or LPM and were divided into high or low respiratory rate (RR) groups. A qualitative image quality was compared between the two modes. The volume CT dose index (CTDIvol) and dose-length product (DLP) were evaluated from the dose reports, and effective doses were assessed using a paediatric phantom. RESULTS: Image quality was generally better for HPM than LPM (diagnostic acceptance score, 4.00 vs. 3.46, P = 0.004); the difference was more prominent in the high RR group (4.00 vs. 3.22, P = 0.001). However, there was no significant difference in the low RR group. The mean DLP value was higher in HPM than LPM (29.48 mGy · cm vs. 23.46 mGy · cm, P = 0.022), while CTDIvol was not significantly different. The total effective radiation dose was 26 % higher in HPM than LPM (1.82 mSv vs. 1.44 mSv). CONCLUSIONS: LPM can be considered for paediatric lung evaluation in young children with low RRs to reduce radiation dose while maintaining favourable image quality. KEY POINTS: • Radiation exposure is higher on high-pitch "Flash spiral mode" than on low-pitch "X-CARE mode". • "Flash spiral mode" generally showed better image quality than "X-CARE mode". • Difference in image quality was more prominent in the high RR group. • There was no difference in image quality in the low RR group. • "X-CARE mode" should be considered in a limited population with low RRs.

Free-Breathing Radial 3D Fat-Suppressed T1-Weighted Gradient-Echo Sequence for Contrast-Enhanced Pediatric Spinal Imaging: Comparison With T1-Weighted Turbo Spin-Echo Sequence.

OBJECTIVE: The purpose of this study was to compare free-breathing radially sampled 3D T1-weighted gradient-echo acquisitions (radial volumetric interpolated breath-hold examination [VIBE]) with a T1-weighted turbo spin-echo (TSE) sequence for contrast-enhanced spinal imaging of children with CNS tumors. MATERIALS AND METHODS: Twenty-eight consecutively registered children with CNS tumors underwent evaluation of leptomeningeal seeding with 1.5-T MRI that included both radial VIBE and T1-weighted TSE sequences. For qualitative analysis, overall image quality; presence of motion, CSF flow, and radial artifacts; and lesion conspicuity were retrospectively assessed with scoring systems. The signal-intensity uniformity of each sequence was evaluated for quantitative comparison. The acquisition times for each sequence were compared. RESULTS: Images obtained with the radial VIBE sequence had a higher overall image quality score than did T1-weighted TSE images (3.61 ± 0.73 vs 2.80 ± 0.69, p < 0.001) and lower motion artifact (0.82 ± 0.43 vs 1.29 ± 0.56, p = 0.001) and CSF flow artifact (0 vs 1.68 ± 0.67, p < 0.001) scores. Radial artifacts were found only on radial VIBE images (1.36 ± 0.31 vs 0, p < 0.001). In 13 patients with spinal seeding nodules, radial VIBE images showed greater lesion conspicuity than did T1-weighted TSE images (4.23 ± 0.52 vs 2.47 ± 0.57, p = 0.005). Radial VIBE images had diminished signal-intensity variation compared with T1-weighted TSE images in air, spine, and muscle (p < 0.01). The mean acquisition times were not significantly different between the two sequences (p = 0.117). CONCLUSION: For pediatric spinal imaging, radial VIBE images had better image quality and lesion conspicuity and fewer CSF and respiratory motion artifacts than did T1-weighted TSE images in a similar acquisition time.

Knowledge-based iterative model reconstruction: comparative image quality and radiation dose with a pediatric computed tomography phantom.

BACKGROUND: CT of pediatric phantoms can provide useful guidance to the optimization of knowledge-based iterative reconstruction CT. OBJECTIVE: To compare radiation dose and image quality of CT images obtained at different radiation doses reconstructed with knowledge-based iterative reconstruction, hybrid iterative reconstruction and filtered back-projection. MATERIALS AND METHODS: We scanned a 5-year anthropomorphic phantom at seven levels of radiation. We then reconstructed CT data with knowledge-based iterative reconstruction (iterative model reconstruction [IMR] levels 1, 2 and 3; Philips Healthcare, Andover, MA), hybrid iterative reconstruction (iDose(4), levels 3 and 7; Philips Healthcare, Andover, MA) and filtered back-projection. The noise, signal-to-noise ratio and contrast-to-noise ratio were calculated. We evaluated low-contrast resolutions and detectability by low-contrast targets and subjective and objective spatial resolutions by the line pairs and wire. RESULTS: With radiation at 100 peak kVp and 100 mAs (3.64 mSv), the relative doses ranged from 5% (0.19 mSv) to 150% (5.46 mSv). Lower noise and higher signal-to-noise, contrast-to-noise and objective spatial resolution were generally achieved in ascending order of filtered back-projection, iDose(4) levels 3 and 7, and IMR levels 1, 2 and 3, at all radiation dose levels. Compared with filtered back-projection at 100% dose, similar noise levels were obtained on IMR level 2 images at 24% dose and iDose(4) level 3 images at 50% dose, respectively. Regarding low-contrast resolution, low-contrast detectability and objective spatial resolution, IMR level 2 images at 24% dose showed comparable image quality with filtered back-projection at 100% dose. Subjective spatial resolution was not greatly affected by reconstruction algorithm. CONCLUSION: Reduced-dose IMR obtained at 0.92 mSv (24%) showed similar image quality to routine-dose filtered back-projection obtained at 3.64 mSv (100%), and half-dose iDose(4) obtained at 1.81 mSv.

Early imaging findings in germ cell tumors arising from the basal ganglia.

BACKGROUND: It is difficult to diagnosis early stage germ cell tumors originating in the basal ganglia, but early recognition is important for better outcome. OBJECTIVE: To evaluate serial MR images of basal ganglia germ cell tumors, with emphasis on the features of early stage tumors. MATERIALS AND METHODS: We retrospectively reviewed serial MR images of 15 tumors in 14 children and young adults. We categorized MR images of the tumors as follows: type I, ill-defined patchy lesions (<3 cm) without cyst; type II, small mass lesions (<3 cm) with cyst; and type III, large lesions (≥3 cm) with cyst. We also assessed temporal changes of the MR images. RESULTS: On the initial images, 8 of 11 (73%) type I tumors progressed to types II or III, and 3 of 4 (75%) type II tumors progressed to type III. The remaining 4 tumors did not change in type. All type II tumors (5/5, 100%) that changed from type I had a few tiny cysts. Intratumoral hemorrhage was observed even in the type I tumor. Ipsilateral hemiatrophy was observed in most of the tumors (13/15, 87%) on initial MR images. As tumors grew, cystic changes, intratumoral hemorrhage, and ipsilateral hemiatrophy became more apparent. CONCLUSION: Early stage basal ganglia germ cell tumors appear as ill-defined small patchy hyperintense lesions without cysts on T2-weighted images, are frequently associated with ipsilateral hemiatrophy, and sometimes show microhemorrhage. Tumors develop tiny cysts at a relatively early stage.

Pediatric Chest CT: Wide-Volume and Helical Scan Modes in 320-MDCT.

OBJECTIVE: The purpose of this study was to compare wide-volume and helical pediatric 320-MDCT of the chest with respect to radiation dose and image quality. MATERIALS AND METHODS: From November 2012 to September 2013, 59 wide-volume and 47 helical pediatric chest 320-MDCT images were obtained. The same tube potential and effective tube current-time product were applied in the two groups according to patient weight (group A, < 10 kg, n = 18; group B, 10-19.9 kg, n = 60; group C, 20-39.9 kg, n = 28). To compensate for overranging, adjusted CT dose index (CTDI) was calculated by dividing dose-length product (DLP) by the scan ranges imaged. Adjusted CTDI, DLP, overall image quality, motion artifact, noise, and scan ranges were compared by Mann-Whitney U test or t test. RESULTS: The adjusted CTDI was significantly lower in the group who underwent wide-volume CT than in the group who underwent helical CT (weight group A, p < 0.001; group B, p < 0.001; group C, p = 0.003). The DLP was lower in the wide-volume group than in the helical CT group in weight groups A (p < 0.001) and B (p < 0.001) but not in group C (p = 0.162). All CT scans were of diagnostic quality, and there was no significant difference between the wide-volume and helical CT groups (p = 0.318). The motion artifact score was significantly higher in the wide-volume group than in the helical CT group in groups B (p < 0.001) and C (p = 0.010) but not in group A (p = 0.931). The noise was significantly lower in the wide-volume group than in the helical CT group (p < 0.001). CONCLUSION: In pediatric chest CT, use of wide-volume CT can decrease radiation exposure while preserving image quality. It is associated with less noise than helical CT but may be subject to more motion artifact.