Role of diffusion-weighted imaging in differentiating benign and malignant pediatric abdominal tumors

Background

Solid malignant tumors are more highly cellular than benign lesions and hence have a restricted diffusion of water molecules.

Objective

To evaluate whether diffusion-weighted MR imaging (DWI) can differentiate between benign and malignant pediatric abdominal tumors.

Materials and methods

We retrospectively analyzed DWI scans of 68 consecutive children with 39 benign and 34 malignant abdominal masses. To calculate the apparent diffusion coefficient (ADC) maps and ADC values, we used 1.5-T sequences at TR/TE/b-value of 5,250–7,500/54–64/b?=?0, 500 and 3-T sequences at 3,500–4,000/66–73/b?=?0, 500, 800. ADC values were compared between benign and malignant and between data derived at 1.5 tesla (T) and at 3 tesla magnetic field strength, using the Mann-Whitney-Wilcoxon test, ANOVA and a receiver operating curve (ROC) analysis.

Results

There was no significant difference in ADC values obtained at 1.5 T and 3 T (P?=?0.962). Mean ADC values (× 10^?3?mm²/s) were 1.07 for solid malignant tumors, 1.6 for solid benign tumors, 2.9 for necrotic portions of malignant tumors and 3.1 for cystic benign lesions. The differences between malignant and benign solid tumors were statistically significant (P?=?0.000025). ROC analysis revealed an optimal cut-off ADC value for differentiating malignant and benign solid tumors as 1.29 with excellent inter-observer reliability (alpha score 0.88).

Conclusion

DWI scans and ADC values can contribute to distinguishing between benign and malignant pediatric abdominal tumors.     

MRI features of atypical teratoid/rhabdoid tumors in children

Background

Atypical teratoid/rhabdoid tumors (AT/RTs) are rare, highly malignant tumors of the central nervous system, usually occurring in young children.

Objective

To investigate the MRI features of AT/RT, with special emphasis on diffusion-weighted imaging (DWI) and MR spectroscopy (MRS).

Materials and methods

MRI findings of 11 children with AT/RT were reviewed retrospectively, including DWI in 9 AT/RT children and MRS in 6 children.

Results

The neoplasms were infratentorial in 4 children and supratentorial in 5 children, both infra- and supratentorial in 1 child and multifocal in 1 child. AT/RT produced heterogeneous signal intensity from peripheral cysts in 7/11 (63%) and hemorrhage in 7/11 (63%). All lesions showed contrast enhancement of varying degrees. Seven (63%) had peritumoral edema. Nine (82%) were hyperintense on DWI with a mean ± SD ADC of 0.60 ± 0.13 × 10^?3?mm² s^?1. Six lesions (55%) exhibited elevated levels of choline and decreased NAA, and three had lipid peaks.

Conclusions

A childhood intracranial tumor with off-midline location, peripheral cystic components, hemorrhage, low ADC, and lipid peaks on MRS suggests AT/RT to be considered a differential diagnosis.     

Diffusion-weighted MRI of abscess formations in children and young adults

Background

Diffusion-weighted MRI (DWI) is helpful for detection of brain abscess and pelvic abscess in adults. In the present study, we evaluated the diagnostic performance of DWI in children and young adults with abdominal and soft tissue abscess formations.

Methods

Seventeen patients (11 females, aged 13 ± 6 years) with suspected abdominal or soft-tissue abscess underwent routine MRI including free-breathing DWI and contrast-enhanced T1w imaging. Seventeen random age-matched patients with non-purulent abdominal fluid collections served as controls. Mean apparent diffusion coefficent (ADC) was measured for abscess, muscle, liver, spleen and kidney tissue as well as for cerebrospinal fluid, urine and free abdominal fluid.

Results

All fluid collections were identified on diffusion-weighted images. Thirteen of 14 confirmed abscess formations showed an ADC < 1.0 × 10^?3 mm²/s with a mean value of 0.80 ± 0.38 mm²/s. One tuberculous softtissue abscess had a higher ADC of 1.85 × 10^?3 mm²/s. Ring enhancement on T1w imaging was seen in three nonpurulent fluid collections. There were no false-positive findings in the control group.

Conclusions

Diffusion-weighted MRI is highly sensitive for abscess and may add specificity to contrast-enhanced T1w imaging of ring-enhancing fluid collections. DWI with free-breathing rapid image acquisition and without the need of intravenous contrast application constitutes a particularly useful choice in pediatric imaging.     

Can diffusion-weighted imaging distinguish between benign and malignant pediatric liver tumors?

Background

There are limited data on utility of diffusion-weighted imaging (DWI) in the evaluation of pediatric liver lesions.

Objective

To determine whether qualitative and quantitative DWI can be used to differentiate benign and malignant pediatric liver lesions.

Materials and methods

We retrospectively reviewed MRIs in children with focal liver lesions to qualitatively evaluate lesions noting diffusion restriction, T2 shine-through, increased diffusion, hypointensity on DWI and apparent diffusion coefficient (ADC) maps, and intermediate signal on both, and to measure ADC values. Pathology confirmation or a combination of clinical, laboratory and imaging features, and follow-up was used to determine final diagnosis.

Results

We included 112 focal hepatic lesions in 89 children (median age 11.5 years, 51 female), of which 92 lesions were benign and 20 malignant. Interobserver agreement was almost perfect for both qualitative (kappa 0.8735) and quantitative (intraclass correlation coefficient [ICC] 0.96) diffusion assessment. All malignant lesions showed diffusion restriction. Most benign lesions other than abscesses were not restricted. There was significant association of qualitative restriction with malignancy and non-restriction with benignancy (Fisher exact test P<0.0001). Mean normalized ADC values of malignant lesions (1.23x10^?3 mm²/s) were lower than benign lesions (1.62x10^?3 mm²/s; Student’s t-test, P<0.015). However, there was significant overlap of ADC between benign and malignant lesions, with wide range for each diagnosis. Receiver operating characteristic (ROC) analysis revealed an area under the curve (AUC) of 0.63 for predicting malignancy using an ADC cut-off value of ≤1.20x10^?3 mm²/s, yielding a sensitivity of 78% and a specificity of 54% for differentiating malignant from benign lesions.

Conclusion

Qualitative diffusion restriction in pediatric liver lesions is a good predictor of malignancy and can help to differentiate between benign and malignant lesions, in conjunction with conventional MR sequences. Even though malignant lesions demonstrated significantly lower ADC values than benign lesions, the use of quantitative diffusion remains limited in its utility for distinguishing them because of the significant overlap and wide ranges of ADC values.

     

Magnetic resonance imaging in children with sickle cell disease—detecting alterations in the apparent diffusion coefficient in hips with avascular necrosis

Background

Avascular necrosis (AVN) is a common morbidity in children with sickle cell disease (SCD) that leads to pain and joint immobility. However, the diagnosis is often uncertain or delayed.

Objective

To examine the ability of apparent diffusion coefficient (ADC) measurements on diffusion-weighted imaging to detect AVN in children with SCD.

Materials and methods

ADC values were calculated at the hips of normal children (n?=?19) and children with SCD who were either asymptomatic with no known previous hip disease (n?=?13) or presented for the first time with clinical symptoms of hip pathology (n?=?12). ADC values were compared for differences among groups with and without AVN using non-parametric statistical methods.

Results

The ADC values were elevated in the hips of children with AVN (median ADC?=?1.57?×?10^?3?mm²/s [95% confidence interval?=?0.86–2.10]) and differed significantly in pairwise comparisons (all P?Conclusion Children with sickle cell disease have elevated apparent diffusion coefficient values in their affected hips on initial diagnosis of avascular necrosis.     

Small-bowel MRI in children and young adults with Crohn disease: retrospective head-to-head comparison of contrast-enhanced and diffusion-weighted MRI

Background

Small-bowel MRI based on contrast-enhanced T1-weighted sequences has been challenged by diffusion-weighted imaging (DWI) for detection of inflammatory bowel lesions and complications in patients with Crohn disease.

Objective

To evaluate free-breathing DWI, as compared to contrast-enhanced MRI, in children, adolescents and young adults with Crohn disease.

Materials and methods

This retrospective study included 33 children and young adults with Crohn disease ages 17?±?3 years (mean ± standard deviation) and 27 matched controls who underwent small-bowel MRI with contrast-enhanced T1-weighted sequences and DWI at 1.5 T. The detectability of Crohn manifestations was determined. Concurrent colonoscopy as reference was available in two-thirds of the children with Crohn disease.

Results

DWI and contrast-enhanced MRI correctly identified 32 and 31 patients, respectively. All 22 small-bowel lesions and all Crohn complications were detected. False-positive findings (two on DWI, one on contrast-enhanced MRI), compared to colonoscopy, were a result of large-bowel lumen collapse. Inflammatory wall thickening was comparable on DWI and contrast-enhanced MRI. DWI was superior to contrast-enhanced MRI for detection of lesions in 27% of the assessed bowel segments and equal to contrast-enhanced MRI in 71% of segments.

Conclusion

DWI facilitates fast, accurate and comprehensive workup in Crohn disease without the need for intravenous administration of contrast medium. Contrast-enhanced MRI is superior in terms of spatial resolution and multiplanar acquisition.     

MRI diffusion-weighted imaging (DWI) in pediatric small bowel Crohn disease: correlation with MRI findings of active bowel wall inflammation

Background

Restricted diffusion on diffusion-weighted imaging (DWI) sequences during magnetic resonance enterography (MRE) has been shown in segments of bowel affected by Crohn disease. However, the exact meaning of this finding, particularly within the pediatric Crohn disease population, is poorly understood.

Objective

The purpose of this study was to determine the significance of bowel wall restricted diffusion in children with small bowel Crohn disease by correlating apparent diffusion coefficient (ADC) values with other MRI markers of disease activity.

Materials and methods

A retrospective review of pediatric patients (≤ 18 years of age) with Crohn disease terminal ileitis who underwent MRE with DWI at our institution between May 1, 2009 and May 31, 2011 was undertaken. All of the children had either biopsy-proven Crohn disease terminal ileitis or clinically diagnosed Crohn disease, including terminal ileal involvement by imaging. The mean minimum ADC value within the wall of the terminal ileum was determined for each examination. ADC values were tested for correlation/association with other MRI findings to determine whether a relationship exists between bowel wall restricted diffusion and disease activity.

Results

Forty-six MRE examinations with DWI in children with terminal ileitis were identified (23 girls and 23 boys; mean age, 14.3 years). There was significant negative correlation or association between bowel wall minimum ADC value and established MRI markers of disease activity, including degree of bowel wall thickening (R?=?(?)0.43; P?=?0.003), striated pattern of arterial enhancement (P?=?0.01), degree of arterial enhancement (P?=?0.01), degree of delayed enhancement (P?=?0.045), amount of mesenteric inflammatory changes (P?<?0.0001) and presence of a stricture (P?=?0.02). ADC values were not significantly associated with bowel wall T2-weighted signal intensity, length of disease involvement or mesenteric fibrofatty proliferation.

Conclusion

Increasing bowel wall restricted diffusion (lower ADC values) is associated with multiple MRI findings that are traditionally associated with active inflammation in pediatric small bowel Crohn disease.     

Serial diffusion-weighted MRI correlates with clinical course and treatment response in children with intracranial pus collections

Background Accurate assessment of treatment response in children with intracranial pus collections is vital to guide appropriate therapy and reduce morbidity and mortality. Objective To correlate serial MR-measurable changes in diffusion-weighted imaging (DWI) with clinical response to treatment. Materials and methods We retrospectively reviewed clinical notes, conventional MR sequences and DWI in eight children with intracranial pus collections. Trace DWI signal intensity and apparent diffusion coefficient (ADC) values were compared at three time points: at initial diagnosis (eight children, 13 collections), at follow-up during continued clinical infection (three children, sp collections), and at follow-up when clinical infection had resolved (seven children, 12 collections). Results At initial diagnosis all patients were septic and collections showed restricted diffusion (mean ADC 0.61±0.15×10⁻³mm²/s). Patients with persistent clinical sepsis at follow-up DWI had collections with persistent low ADC values (0.66±0.21×10⁻³mm²/s), significantly (P<0.001) below normal cortical gray matter values. Successful resolution of the infection was associated with a significant rise in ADC values (1.57±0.57×10⁻³mm²/s, P<0.01) compared both to patients with signs of continued sepsis and to normal gray matter values. Conclusion Persistent restricted diffusion in pus collections correlates with continued sepsis. Treatment response is associated with clinical resolution of sepsis and ADC value elevation significantly above normal gray matter values. Presented at ESPR 2005, Dublin, Ireland     

The Gini coefficient: a methodological pilot study to assess fetal brain development employing postmortem diffusion MRI

Background

Diffusion-weighted imaging (DWI) is important in the assessment of fetal brain development. However, it is clinically challenging and time-consuming to prepare neuromorphological examinations to assess real brain age and to detect abnormalities.

Objective

To demonstrate that the Gini coefficient can be a simple, intuitive parameter for modelling fetal brain development.

Materials and methods

Postmortem fetal specimens(n?=?28) were evaluated by diffusion-weighted imaging (DWI) on a 3-T MRI scanner using 60 directions, 0.7-mm isotropic voxels and b-values of 0, 150, 1,600 s/mm². Constrained spherical deconvolution (CSD) was used as the local diffusion model. Fractional anisotropy (FA), apparent diffusion coefficient (ADC) and complexity (CX) maps were generated. CX was defined as a novel diffusion metric. On the basis of those three parameters, the Gini coefficient was calculated.

Results

Study of fetal brain development in postmortem specimens was feasible using DWI. The Gini coefficient could be calculated for the combination of the three diffusion parameters. This multidimensional Gini coefficient correlated well with age (Adjusted R²?=?0.59) between the ages of 17 and 26 gestational weeks.

Conclusions

We propose a new method that uses an economics concept, the Gini coefficient, to describe the whole brain with one simple and intuitive measure, which can be used to assess the brain’s developmental state.     

Massive splenic infarction in children with sickle cell anemia and the role of splenectomy

Background

Massive splenic infarction (MSI) is a very rare condition. Few reports of splenic infarction of various etiologies including hematological and non-hematological causes have been published. On the other hand, MSI in patients with sickle cell anemia (SCA) is extremely rare. This report describes our experience with 15 children with SCA and MSI outlining aspects of presentation, diagnosis and management.

Patients and methods

The records of all children with MSI were retrospectively reviewed for age at diagnosis, sex, clinical features, precipitating factors, investigations, management and outcome.

Results

15 children (11 M: 4 F) with SCA were treated for MSI. Their mean age was 10.9 years (6–17 years). All presented with severe left upper quadrant abdominal pain. In nine, this was associated with nausea and vomiting. Three were febrile and all had a tender splenomegaly. Their mean hemoglobin was 8.2 g/dl (5.7–11.3 g/dl), mean WBC was 10.97 × 10³ mm^?3 (3.6 × 10³–22.3 × 10³ mm^?3) and mean platelet count was 263.3 × 10³ mm^?3 (40 × 10³–660 × 10³ mm^?3). In seven, there was a precipitating cause including high altitude in two, acute chest syndrome in two, septicemia in two and severe vasooclusive crisis in one. Abdominal ultrasound and CT scan confirmed the diagnosis of MSI which involved more than half of the spleen in 12 and whole spleen in 3. All were treated with IV fluids, analgesia and blood transfusion where appropriate. Eleven had splenectomy because of persistent abdominal pain, three developed splenic abscess and underwent splenectomy and one settled on conservative treatment. Histology confirmed the diagnosis of splenic infarction in 11 and infarction with abscess in the remaining 3.

Conclusion

MSI is extremely rare in children with SCA. It can develop spontaneously or precipitated by other factors namely high altitude, acute chest syndrome and severe stress. Most reported cases of splenic infarction are small in size, focal and can be treated conservatively. MSI, on the other hand, may necessitate splenectomy for persistent symptoms or in case of complications, such as abscess formation.     

Age-related apparent diffusion coefficients of lumbar vertebrae in healthy children at 1.5 T

Background

Diffusion-weighted magnetic resonance imaging with apparent diffusion coefficient (ADC) calculation is important for detecting bone marrow pathologies.

Objective

To investigate age-related differences of lumbar vertebral body ADC to establish normal values for healthy children.

Materials and methods

Forty-nine healthy children without any history of oncological or hematological diseases (10.2±4.7 years, range: 0–20 years) were included in this retrospective study. All magnetic resonance imaging (MRI) examinations were performed at 1.5 T and with similar scan parameters. The diffusion-weighted sequences were performed with b values of 50, 400 and 800 s/mm². ADC values were measured by placing regions of interest at three different levels within each lumbar vertebral body (L1 to L5). ADC values were analyzed for different age groups (0–2 years, 3–6 years, 7–11 years, 12–14 years, 15–20 years), for each vertebral and intravertebral level.

Results

The mean ADC of the whole study group was 0.60±0.09?×?10^?3 mm²/s. Children between the ages of 12 and 14 years had significantly higher ADC compared to the other age groups (P≤0.0003). ADC values were significantly higher in the 1st lumbar vertebral body compared to the other levels of the lumbar spine (P<0.005) with the exception of L5, and in the upper third of the vertebral bodies compared to the middle or lower thirds (P≤0.003).

Conclusion

The age-, vertebral- and intravertebral level-dependent differences in ADC suggest a varying composition and cellularity in different age groups and in different locations.

     

Ultrasound-guided core needle biopsy in diagnosis of abdominal and pelvic neoplasm in pediatric patients

Background

Ultrasound-guided core needle biopsy of abdominal and pelvic masses in adults has gained tremendous popularity. However, the application of the same treatment in children is not as popular because of apprehensions regarding inadequate tissues for the biopsy and accidental puncture of vital organs.

Methods

Data of the application of ultrasound-guided core needle biopsy in 105 pediatric patients with clinically or ultrasound-diagnosed abdominopelvic masses were reviewed. Diagnostic procedures were conducted in our institution from May 2011 to May 2013.

Results

The biopsies were conducted on 86 malignant lesions and 19 benign lesions. 86 malignant tumors comprised neuroblastomas (30 cases), hepatoblastomas (15 cases), nephroblastomas (11 cases), and primitive neuroectodermal tumors/malignant small round cells (6 cases). Among malignant tumor cases, only a pelvic primitive neuroectodermal tumor did not receive a pathological diagnosis. Therefore, the biopsy accuracy was 98.8 % in malignant tumor. However, the biopsies for one neuroblastomas and one malignant small round cell tumor were inadequate for cytogenetic analysis. Therefore, 96.5 % of the malignant tumor patients received complete diagnosis via biopsy. 19 benign tumors comprised mature teratoma (10 cases), hemangioendothelioma (3 cases), paraganglioma (2 cases), and infection (2 cases). The diagnostic accuracy for benign neoplasm was 100 %. Five patients experienced postoperative complications, including pain (2 patients), bleeding from the biopsy site (2 patients), and wound infection (1 patient).

Conclusion

Ultrasound-guided core needle biopsy is an efficient, minimally invasive, accurate, and safe diagnostic method that can be applied in the management of abdominal or pelvic mass of pediatric patients.     

Intravoxel incoherent motion magnetic resonance imaging of the knee joint in children with juvenile idiopathic arthritis

Background

MRI of synovitis relies on use of a gadolinium-based contrast agent. Diffusion-weighted MRI (DWI) visualises thickened synovium but is of limited use in the presence of joint effusion.

Objective

To investigate the feasibility and diagnostic accuracy of diffusion-weighted MRI with intravoxel incoherent motion (IVIM) for diagnosing synovitis in the knee joint of children with juvenile idiopathic arthritis.

Materials and methods

Twelve consecutive children with confirmed or suspected juvenile idiopathic arthritis (10 girls, median age 11 years) underwent MRI with contrast-enhanced T1-weighted imaging and DWI at 1.5 T. Read-out segmented multi-shot DWI was acquired at b values of 0 s/mm², 200 s/mm², 400 s/mm² and 800 s/mm². We calculated the IVIM parameters perfusion fraction (f) and tissue diffusion coefficient (D). Diffusion-weighted images at b=800 s/mm², f parameter maps and post-contrast T1-weighted images were retrospectively assessed by two independent readers for synovitis using the Juvenile Arthritis MRI Scoring system.

Results

Seven (58%) children showed synovial hypertrophy on contrast-enhanced imaging. Diagnostic ratings for synovitis on DWI and on f maps were fully consistent with contrast-enhanced imaging, the diagnostic reference. Two children had equivocal low-confidence assessments on DWI. Median f was 6.7±2.0% for synovitis, 2.1±1.2% for effusion, 5.0±1.0% for muscle and 10.6±5.7% for popliteal lymph nodes. Diagnostic confidence was higher based on f maps in three (25%) children and lower in one child (8%), as compared to DWI.

Conclusion

DWI with IVIM reliably visualises synovitis of the knee joint. Perfusion fraction maps differentiate thickened synovium from joint effusion and hence increase diagnostic confidence.

     

Prognostic value of diffusion-weighted imaging summation scores or apparent diffusion coefficient maps in newborns with hypoxic-ischemic encephalopathy

Background

The diagnostic and prognostic assessment of newborn infants with hypoxic-ischemic encephalopathy (HIE) comprises, among other tools, diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps.

Objective

To compare the ability of DWI and ADC maps in newborns with HIE to predict the neurodevelopmental outcome at 2 years of age.

Materials and methods

Thirty-four term newborns with HIE admitted to the Neonatal Intensive Care Unit of Modena University Hospital from 2004 to 2008 were consecutively enrolled in the study. All newborns received EEG, conventional MRI and DWI within the first week of life. DWI was analyzed by means of summation (S) score and regional ADC measurements. Neurodevelopmental outcome was assessed with a standard 1–4 scale and the Griffiths Mental Developmental Scales - Revised (GMDS-R).

Results

When the outcome was evaluated with a standard 1–4 scale, the DWI S scores showed very high area under the curve (AUC) (0.89) whereas regional ADC measurements in specific subregions had relatively modest predictive value. The lentiform nucleus was the region with the highest AUC (0.78). When GMDS-R were considered, DWI S scores were good to excellent predictors for some GMDS-R subscales. The predictive value of ADC measurements was both region- and subscale-specific. In particular, ADC measurements in some regions (basal ganglia, white matter or rolandic cortex) were excellent predictors for specific GMDS-R with AUCs up to 0.93.

Conclusions

DWI S scores showed the highest prognostic value for the neurological outcome at 2 years of age. Regional ADC measurements in specific subregions proved to be highly prognostic for specific neurodevelopmental outcomes.     

How specific is the MRI appearance of supratentorial atypical teratoid rhabdoid tumors?

Background

Supratentorial atypical teratoid rhabdoid tumor (ATRT) in many cases has a distinctive appearance on post-gadolinium MRI.

Objective

We sought to determine whether this is a unique appearance allowing ATRT to be distinguished accurately from other types of pediatric supratentorial tumors.

Materials and methods

Retrospective review of all available preoperative MRI of pediatric supratentorial tumors at two tertiary children’s hospitals, and systematic literature review of case series and reports describing the MRI imaging appearances of supratentorial ATRT.

Results

We had 61 supratentorial tumors, including 32 gliomas, 6 ATRT, 8 ependymomas, 6 gangliogliomas, 2 pilomyxoid astrocytomas, 3 primitive neuro-ectodermal tumors, 2 choroid plexus papillomas, and 2 meningiomas. ATRT presented in significantly younger patients than astrocytomas (mean age 2.6 years vs. 9.9 years, P?<?0.05). The visual pattern of a thick, wavy (irregular) heterogeneously enhancing wall around a cystic center was seen in 5/6 (83%) ATRTs and only 3/55 (5.4%) other tumors (P?<?0.0001), for specificity of 95%, sensitivity of 83%, positive predictive value of 63% and a negative predictive value of 95%.

Conclusion

A supratentorial tumor with a thick, wavy (irregular) heterogeneously enhancing wall surrounding a central cystic region is suggestive of ATRT in the appropriate clinical setting, especially in a child of preschool age.     

Differentiation between high and low grade tumours in paediatric patients by using apparent diffusion coefficients

ObjectiveThis study was performed to confirm the hypothesis that pre-operative apparent diffusion coefficient (ADC) can be used to distinguish between “low grade” and “high grade” tumours in paediatric patients.Material and methodsADC values were retrospectively evaluated in thirty-six paediatric brain tumours. Twenty-one children with low grade brain tumours (12 WHO I astrocytomas, 1 giant cell tumour, 1 pilomyxoid astrocytoma, 4 WHO II astrocytomas, 2 craniopharyngiomas and 1 ganglioglioma) and 15 children with high grade brain tumours (6 medulloblastomas, 3 WHO III ependymomas, 1 PNET, 1 malignant rhabdoid tumour, 1 malignant germ cell tumour, 1 WHO III astrocytoma, 1 WHO IV astrocytoma, 1 rhabdomyosarcoma metastasis) were included in this study. Minimum and mean ADC values were compared between low grade and high grade tumours and cut-off values were evaluated.ResultsThe cut-off values to differentiate low and high grade paediatric brain tumours were 0.7 × 10⁻³ mm²/s and 1.0 × 10⁻³ mm²/s for minimum ADC and average ADC values respectively. All but one high grade infratentorial ependymoma showed significantly lower ADC values than low grade brain tumours in children.ConclusionCombining the information obtained from conventional MR imaging with the ADC values may increase the accuracy of pre-operative differentiation between low grade and high grade paediatric tumours. Cut-off values can help to discern low from high grade tumours. However, it has to be considered that there is a substantial overlap between tumour types previously described in the literature.     

Solid tumors in Turkish children: a multicenter study

Background

This paper presents a detailed incidence study on childhood solid tumors comprising a histopathology-based documentation of benign and malignant lesions.

Methods

The Ankara Pediatric Pathology Working Group collected databases of pediatric solid tumors from six pediatric reference centers in order to analyze the incidence, distribution and some epidemiologic characteristics of the tumors and to establish a multicenter database for further studies. A five-year retrospective archive search was carried out. Excluding epithelial tumors of the skin, leukemia, lymphoreticular system neoplasias, metastatic tumors, and hamartomas, 1362 solid tumors in 1358 patients were classified according to age, sex, localization, histopathology and clinical behavior.

Results

The male/female ratio was 0.9; 14.8% (201) of the patients belonged to 0-1 year age group, 20.7% (281) to 2–4 years, 25.9% (352) to 5–10 years, 22.2% (301) to 11–14 years, and 16.4% (223) to 15-18 years. Among all tumors, 708 (52.0%) were malignant, 645 (47.4%) benign tumors, 2 (0.1%) borderline tumors, and 2 (0.1%) unknown behavioral tumors. Malignant tumors were found in 50.2% (357) of female patients and in 54.0% (349) of male patients. A balanced distribution between benign and malignant entities among children under 18 years was observed. Comparison between the age groups revealed malignant cases outnumbered benign cases under 4 years of age while benign tumor numbers increased after 10 years of age. The most common entities in the malignant group were of sympathetic nervous system origin, while soft tissue tumors far outnumbered the others in the benign group.

Conclusions

We conclude that the cancer patterns of children in the Ankara region mostly resemble with those of the western population. This study provides useful information on the diagnosis of solid tumors in children and highlights variations in cancer incidence in different age groups.     

Effective dose estimation for pediatric upper gastrointestinal examinations using an anthropomorphic phantom set and metal oxide semiconductor field-effect transistor (MOSFET) technology

Background

There is a need for updated radiation dose estimates in pediatric fluoroscopy given the routine use of new dose-saving technologies and increased radiation safety awareness in pediatric imaging.

Objective

To estimate effective doses for standardized pediatric upper gastrointestinal (UGI) examinations at our institute using direct dose measurement, as well as provide dose-area product (DAP) to effective dose conversion factors to be used for the estimation of UGI effective doses for boys and girls up to 10 years of age at other centers.

Materials and methods

Metal oxide semiconductor field-effect transistor (MOSFET) dosimeters were placed within four anthropomorphic phantoms representing children ≤10 years of age and exposed to mock UGI examinations using exposures much greater than used clinically to minimize measurement error. Measured effective dose was calculated using ICRP 103 weights and scaled to our institution’s standardized clinical UGI (3.6-min fluoroscopy, four spot exposures and four examination beam projections) as determined from patient logs. Results were compared to Monte Carlo simulations and related to fluoroscope-displayed DAP.

Results

Measured effective doses for standardized pediatric UGI examinations in our institute ranged from 0.35 to 0.79 mSv in girls and were 3–8% lower for boys. Simulation-derived and measured effective doses were in agreement (percentage differences <19%, T?>?0.18). DAP-to-effective dose conversion factors ranged from 6.5?×10^?4?mSv per Gy-cm² to 4.3?×?10^?3?mSv per Gy-cm² for girls and were similarly lower for boys.

Conclusion

Using modern fluoroscopy equipment, the effective dose associated with the UGI examination in children ≤10 years at our institute is <?1 mSv. Estimations of effective dose associated with pediatric UGI examinations can be made for children up to the age of 10 using the DAP-normalized conversion factors provided in this study. These estimates can be further refined to reflect individual hospital examination protocols through the use of direct organ dose measurement using MOSFETs, which were shown to agree with Monte Carlo simulated doses.     

Intestinal lesions in pediatric Crohn disease: comparative detectability among pulse sequences at MR enterography

Background

Variable sequences can be used in MR enterography, and no consensus exists for the best protocol in children with Crohn disease.

Objective

To compare the lesion detectability of various MR enterography sequences and to correlate the findings of these sequences with the Pediatric Crohn’s Disease Activity Index (PCDAI) in children with Crohn disease.

Materials and methods

Children with clinically or pathologically confirmed Crohn disease underwent MR enterography, including a single-shot fast spin-echo (SSFSE) sequence, motility imaging (coronal 2-D balanced fast field echo), diffusion-weighted imaging (DWI), and dynamic contrast enhancement imaging (including arterial, portal and delayed phases). The lesion detectability of each sequence was graded 0–2 for each involved bowel segment. The lesion detectability and PCDAI result on different sequences were compared using the weighted least squares method and Student’s t-test, respectively.

Results

Fifteen children (11 boys, 4 girls, mean age 13.7?±?1.4 years) with a total of 41 lesions were included in this study. All lesions detected in more than two sequences were visible on the single-shot fast spin-echo (SSFSE) sequence. The relative lesion detection rate was 78.1% on motility imaging, 90.2% on DWI, and 92.7% on arterial, 95.1% on portal and 95.1% on delayed phase imaging. Compared to the SSFSE sequence, motility imaging (P?<?0.001) and DWI (P?=?0.039) demonstrated lower detectability. The mean PCDAI result in the detected lesions was statistically higher only on dynamic enhancement imaging (P?<?0.001).

Conclusion

All MR enterography sequences were found to have relatively high lesion detectability in children with Crohn disease, while motility imaging showed the lowest lesion detectability. Lesions detected on dynamic enhancement imaging showed a higher PCDAI result, which suggests that this sequence is specific for active inflammation.     

Systematic review of ablation techniques for the treatment of malignant or aggressive benign lesions in children

Background

Ablation techniques are widely used for solid malignant tumors in adults. There is no large series assessing the effectiveness of local ablative therapies in the treatment of malignant or aggressive benign lesions in children.

Objective

To review the existing evidence on the techniques and results of ablation for pediatric solid malignant or aggressive benign tumors.

Materials and methods

We searched MEDLINE for papers published between 1995 and 2012 that reported outcomes of radiofrequency, microwave and cryoablation, interstitial laser therapy, irreversible electroporation and percutaneous ethanol injection for patients younger than 18 years old. Data collection included factors related to the patient, tumor biology, ablation technique and cancer-specific endpoints. Additional series of predominantly adults including data on patients younger than 18 years old were also identified.

Results

We identified 28 patients treated by ablation in 29 regions: 5 patients undergoing ablation for liver lesions, 9 patients for lung metastases, 11 patients for bone and/or soft tissue and 4 patients for kidney or pancreas. The ablation was performed to treat primary tumors, local recurrences and metastases. The histology of the tumors was osteosarcoma in 6 patients, Wilms tumor in 3, rhabdomyosarcoma in 3, hepatoblastoma in 3, desmoid tumor in 3, adrenocortical carcinoma in 2 and a single case each of leiomyosarcoma, Ewing sarcoma, paraganglioma, solid-pseudopapillary neoplasm, sacrococcygeal teratoma, hepatic adenoma, juxtaglomerular cell tumor and plantar fibromatosis. Eighteen of the patients (64%) experienced a complication, but only 6 (21%) of these needed treatment other than supportive care.

Conclusions

Although ablative techniques are feasible and promising treatments for certain pediatric tumors, large multicenter prospective trials will be needed to establish efficacy.