[Diagnostic Imaging for Physical Abuse in Children]. / ì‹ ì²´ì  학대를 받은 아동의 ì§„ë‹¨ì  영상.

Physical abuse is a significant cause of morbidity and mortality in the pediatric population. Young children, particularly in the first year of life, are most vulnerable to physical abuse. To evaluate suspected physical abuse, radiologists play a vital role by detecting radiological findings suggestive of physical abuse and differentiating them from other pathologies. This review focuses on radiologic findings, including those for fractures, abusive head trauma, spinal injury, and thoracoabdominal injury, commonly discovered in physically abused children, with special emphasis on biomechanical forces that produce injuries.

Triple rule-out computed tomography for risk stratification of patients with acute chest pain.

AIMS: Clinical evidence supporting triple rule-out computed tomography (TRO-CT) for rapid screening of cardiovascular disease is limited. We investigated the clinical value of TRO-CT in patients with acute chest pain. METHODS: We retrospectively enrolled 1024 patients who visited the emergency department (ED) with acute chest pain and underwent TRO-CT using a 128-slice CT system. TRO-CT was classified as "positive" if it revealed clinically significant cardiovascular disease including obstructive coronary artery disease, pulmonary thromboembolism, or acute aortic syndrome. The clinical endpoint was occurrence of a major adverse cardiovascular event (MACE) within 30 days, defined by a composite of all cause death, myocardial infarction, revascularization, major cardiovascular surgery, or thrombolytic therapy. Clinical risk scores for acute chest pain including TIMI, GRACE, Diamond-Forrester, and HEART were determined and compared to the TRO-CT findings. RESULTS: TRO-CT revealed clinically significant cardiovascular disease in 239 patients (23.3%). MACE occurred in 119 patients (49.8%) with positive TRO-CT and in 7 patients (0.9%) with negative TRO-CT (p < 0.001). Sensitivity, specificity, positive predictive value, and negative predictive value of TRO-CT was 95%, 88%, 54%, and 99%, respectively. TRO-CT was a better discriminator between patients with vs. without events as compared to clinical risk scores (c-statistics = 0.91 versus 0.64 to 0.71; integrated discrimination improvement = 0.31 to 0.37; p < 0.001 for all comparisons). Patients with a negative TRO-CT showed shorter ED stay times and admission rates compared to patients with positive TRO-CT, irrespective of clinical risk scores (p < 0.001 for all comparisons). CONCLUSION: Triple rule-out CT has high predictive performance for 30-day MACE and permits rapid triage and low admission rates irrespective of clinical risk scores.

Radiation Doses of Various CT Protocols: a Multicenter Longitudinal Observation Study.

Emerging concerns regarding the hazard from medical radiation including CT examinations has been suggested. The purpose of this study was to observe the longitudinal changes of CT radiation doses of various CT protocols and to estimate the long-term efforts of supervising radiologists to reduce medical radiation. Radiation dose data from 11 representative CT protocols were collected from 12 hospitals. Attending radiologists had collected CT radiation dose data in two time points, 2007 and 2010. They collected the volume CT dose index (CTDIvol) of each phase, number of phases, dose length product (DLP) of each phase, and types of scanned CT machines. From the collected data, total DLP and effective dose (ED) were calculated. CTDIvol, total DLP, and ED of 2007 and 2010 were compared according to CT protocols, CT machine type, and hospital. During the three years, CTDIvol had significantly decreased, except for dynamic CT of the liver. Total DLP and ED were significantly decreased in all 11 protocols. The decrement was more evident in newer CT scanners. However, there was substantial variability of changes of ED during the three years according to hospitals. Although there was variability according to protocols, machines, and hospital, CT radiation doses were decreased during the 3 years. This study showed the effects of decreased CT radiation dose by efforts of radiologists and medical society.

Devastating metabolic brain disorders of newborns and young infants.

Metabolic disorders of the brain that manifest in the neonatal or early infantile period are usually associated with acute and severe illness and are thus referred to as devastating metabolic disorders. Most of these disorders may be classified as organic acid disorders, amino acid metabolism disorders, primary lactic acidosis, or fatty acid oxidation disorders. Each disorder has distinctive clinical, biochemical, and radiologic features. Early diagnosis is important both for prompt treatment to prevent death or serious sequelae and for genetic counseling. However, diagnosis is often challenging because many findings overlap and may mimic those of more common neonatal conditions, such as hypoxic-ischemic encephalopathy and infection. Ultrasonography (US) may be an initial screening method for the neonatal brain, and magnetic resonance (MR) imaging is the modality of choice for evaluating metabolic brain disorders. Although nonspecific imaging findings are common in early-onset metabolic disorders, characteristic patterns of brain involvement have been described for several disorders. In addition, diffusion-weighted images may be used to characterize edema during an acute episode of encephalopathy, and MR spectroscopy depicts changes in metabolites that may help diagnose metabolic disorders and assess response to treatment. Imaging findings, including those of advanced MR imaging techniques, must be closely reviewed. If one of these rare disorders is suspected, the appropriate biochemical test or analysis of the specific gene should be performed to confirm the diagnosis.

Clinical and imaging features of focal nodular hyperplasia in children.

OBJECTIVE: The purpose of this article is to review the clinical and imaging features of focal nodular hyperplasia (FNH) developed in children. MATERIALS AND METHODS: At a single institution, pediatric patients who underwent imaging studies and who had pathologically proven FNH were studied. Clinical characteristics, including presenting symptoms and signs and the presence of underlying disease, were reviewed from the medical records. Imaging features of FNHs, including the number, size, ultrasound echogenicity and vascularity, CT attenuation, MRI signal intensity and enhancement pattern, and the presence of a central scar, were evaluated. RESULTS: Twenty-five patients (11 boys and 14 girls; median age, 8.6 years) were found to have a solitary (n = 23) or multiple (n = 2) FNH lesions with a mean size of 4.9 cm (range, 1-10 cm). Multiple lesions were associated with small size of the lesions and history of malignancy treated by chemotherapy. Most patients were asymptomatic (n = 22). Biliary atresia was the most common underlying disease (n = 5). On ultrasound, FNHs most commonly appeared to be isoechoic and hypervascular. On dynamic CT and MRI, strong enhancement on the arterial phase and becoming isoattenuated or of isointense signal intensity on the portal or delayed phase was common. A central scar was usually noted in large lesions in about half the cases. CONCLUSION: Pediatric FNH is uncommon and usually is found incidentally in otherwise healthy children. However, it may occur in children who have underlying diseases, including biliary atresia. In addition, it can be encountered during surveillance of childhood cancer survivors with less common imaging features, including lack of a central scar and multiplicity.

Sporadic meningioangiomatosis: imaging findings with histopathologic correlations in seven patients.

INTRODUCTION: Meningioangiomatosis (MA) is a rare benign cerebral lesion. We aimed to evaluate the CT and MR features of sporadic MA, with a focus on the correlation between imaging and histopathologic findings. METHODS: CT (n = 7) and MR (n = 8) images of eight patients (6 men and 2 women; mean age, 12.8 years; range, 4-22 years) with pathologically proven MA were retrospectively reviewed. After dividing the MA lesions according to their distribution into cortical and subcortical white matter components, the morphologic characteristics were analyzed and correlated with histopathologic findings in seven patients. RESULTS: CT and MR images showed cortical (n = 4, 50%) and subcortical white matter (n = 7, 88%) components of MA. All four cortical components revealed hyperattenuation on CT scan and T1 isointensity/T2 hypointensity on MR images, whereas subcortical white matter components showed hypoattenuation on CT scan and T1 hypointensity/T2 hyperintensity on MR images. Two cortical components (25%) demonstrated enhancement and one subcortical white matter component demonstrated cystic change. Seven cases were available for imaging-histopathologic correlation. In all seven cases, the cortex was involved by MA and six patients (86%) showed subcortical white matter involvement by MA. There were excellent correlations between the imaging and histopathologic findings in subcortical white matter components, and the accuracy was 100% (seven of seven); whereas there were poor correlations in cortical components, and the accuracy was 43% (three of seven). CONCLUSIONS: The cerebral cortex and subcortical white matter were concomitantly involved by MA. Subcortical white matter components of MA were more apparent than cortical components on CT and MR imaging.

Dynamic MRI findings and clinical features of benign hypervascular hepatic nodules in childhood-cancer survivors.

OBJECTIVE: The purpose of this study is to investigate the dynamic MRI findings and clinical features of benign hypervascular hepatic nodules in childhood-cancer survivors. MATERIALS AND METHODS: We reviewed dynamic MRI findings and clinical features in 15 patients who had been treated for childhood malignant solid tumors and in whom hypervascular hepatic nodules were later found on surveillance imaging by either CT or ultrasound (or both). The benign nature of the lesion was based on histologic examination or clinical and radiologic follow-up (or both). RESULTS: Time between initial diagnosis of malignancy and detection of the hepatic nodule ranged from 4.5 to 13.5 years with the majority of the malignancies being neuroblastoma treated by high-dose chemotherapy and hematopoietic stem cell transplantation. A total of 43 nodules were detected, often multiple and small. Most of the lesions were isointense or slightly hyperintense on T2-weighted imaging and isointense or slightly hypointense on T1-weighted imaging. All nodules had intense enhancement on the arterial phase and were isointense or slightly hyperintense on the delayed phase. A central scar was seen in four. Additionally, hepatic hemosiderosis was noted in four patients, in whom all the lesions were hyperintense on both T1- and T2-weighted imaging. CONCLUSION: Benign hypervascular hepatic nodules in survivors of childhood malignancy occur years after high-dose chemotherapy and hematopoietic stem cell transplantation. Dynamic MRI findings including intense arterial enhancement and absence of washout in the delayed phase are of great value in the differential diagnosis of these hepatic nodules.

Currarino syndrome: variable imaging features in three siblings with HLXB9 gene mutation.

Currarino syndrome (CS) is characterized by the triad of partial sacral defect, anorectal malformation, and presacral mass and has been recently reported to be associated with mutations in the HLXB9 gene, which have been suggested to be the genetic background of CS. Phenotypic expression of the HLXB9 gene mutation in a CS family varies from an incomplete to a complete triad. We present variable clinical and imaging features of CS in three siblings with genetically identified HLXB9 mutation. Clinical presentation, management and outcome were also reviewed, and we suggest that magnetic resonance imaging should be used as a screening tool in the members of a CS family with genetic mutation in order to avoid morbidity and mortality from an undiagnosed presacral mass.

Aspergillus galactomannan antigen assay and invasive aspergillosis in pediatric cancer patients and hematopoietic stem cell transplant recipients.

BACKGROUND: Invasive aspergillosis (IA) is a major cause of morbidity and mortality in immunocompromised children. We investigated the usefulness of an Aspergillus galactomannan (GM) antigen assay as a diagnostic tool for IA in pediatric cancer patients and hematopoietic cell transplantation (HCT) recipients. PROCEDURE: The GM antigen assay results were analyzed in 749 blood samples from 99 patients. A GM index (GMI) greater than or equal to 0.5 on at least two separate occasions was considered positive. A review of the clinical data was performed for subjects with proven or probable IA. RESULTS: Twenty-one of 23 patients with proven or probable IA had positive GM antigen test results (91.3% sensitivity, 95% CI 71.9-98.9; 81.7% specificity, 95% CI 69.6-90.5; P < 0.0001). The false-positive rate was 18.3%. Being younger than 3 years of age, having a solid tumor, and receiving HCT within 4 weeks of the test were statistically significant factors for causing false-positive results (P < 0.05). Among the 23 patients with IA (six proven, 17 probable), 16 (69.6%) had hematological malignancies, five (22.7%) had solid tumors, and two (8.7%) had primary immunodeficiency. Nineteen patients (82.6%) received HCT. The most common clinical site of IA was the lungs (91.3%), and consolidation was the most frequent finding in chest CT scans (36.8%). The mortality at 12 weeks was 43.5%. CONCLUSIONS: Having a positive GM assay at least twice is useful in diagnosing IA in pediatric patients with cancer and HCT recipients.

Can preoperative MR imaging predict optic nerve invasion of retinoblastoma?

PURPOSE: To evaluate the accuracy of pre-operative MRI for the detection of optic nerve invasion in retinoblastoma. MATERIALS AND METHODS: Institutional review board approval and informed consent were waived for this retrospective study. A total of 41 patients were included. Inclusion criteria were histologically proven retinoblastoma, availability of diagnostic-quality preoperative MR images acquired during the 4 weeks before surgery, unilateral retinoblastoma, and normal-sized optic nerve. Two radiologists retrospectively reviewed the MR images independently. Five imaging findings (diffuse mild optic nerve enhancement, focal strong optic nerve enhancement, optic sheath enhancement, tumor location, and tumor size) were evaluated against optic nerve invasion of retinoblastoma. The predictive performance of all MR imaging findings for optic nerve invasion was also evaluated by the receiver operating characteristic curve analysis. RESULTS: Optic nerve invasion was histopathologically confirmed in 24% of study population (10/41). The differences in diffuse mild enhancement, focal strong enhancement, optic sheath enhancement, and tumor location between patients with optic nerve invasion and patients without optic nerve invasion were not significant. Tumor sizes were 16.1mm (SD: 2.2mm) and 14.9 mm (SD: 3.6mm) in patients with and without optic nerve involvement, respectively (P=0.444). P-Values from binary logistic regression indicated that all five imaging findings were not significant predictors of tumor invasion of optic nerve. The AUC values of all MR imaging findings for the prediction of optic nerve invasion were 0.689 (95% confidence interval: 0.499-0.879) and 0.653 (95% confidence interval: 0.445-0.861) for observer 1 and observer 2, respectively. CONCLUSION: Findings of MRI in patients with normal-sized optic nerves have limited usefulness in preoperatively predicting the presence of optic nerve invasion in retinoblastoma.

Hypervascular hepatic nodules in childhood cancer survivors: clinical and imaging features.

AIM: The aim was to review the clinical and imaging features of hypervascular hepatic nodule (HHN) in childhood cancer survivors. MATERIALS AND METHODS: We retrospectively reviewed 11 pediatric patients (female:male, 7:4; age range, 4.0-12.3 years) who had HHNs detected by surveillance computed tomography (CT) after treatment of a malignant solid tumor and subsequently followed by serial imaging without evidence of recurrent malignancy. The lesions were analyzed in terms of number, size, location, CT and ultrasonographic (US) features, and changes in background liver. In addition, clinical features were investigated along with follow-up changes of HHNs by imaging monitoring. RESULTS: Time between initial diagnosis of malignancy and HHN occurrence ranged from 3.2 to 8.5 years (median, 5.8 years). Ten patients had received high-dose chemotherapy and autologous stem cell transplantation for advanced neuroblastoma. A total of 22 nodules were detected, being multiple in six patients and measuring 0.5-3.0 cm in size. At sequential postcontrast CT, nodules demonstrated moderate to strong enhancement during the earlier phase and were isoattenuated during the later phase. On US, they appeared as hypo- or isoechoic lesions. During follow-up, 11 nodules (50%) regressed, 6 (27%) progressed, and 5 (23%) remained stable. Additional HHNs were noted in four patients during follow-up. CONCLUSION: Childhood cancer survivors are at risk of developing HHNs, which are often multiple and small, years after completing chemotherapy. They are nonaggressive and tend to have a benign course, making conservative management reasonable.

Neurodevelopmental outcomes in preterm infants: comparison of infants with and without diffuse excessive high signal intensity on MR images at near-term-equivalent age.

PURPOSE: To compare the neurodevelopmental outcomes between preterm infants with diffuse excessive high signal intensity (DEHSI) and those without DEHSI on magnetic resonance (MR) images, in association with other white matter lesions. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board, and requirement to obtain informed consent was waived. High-risk preterm infants (n = 126) who underwent screening brain MR imaging at near-term-equivalent age were classified into two groups according to the presence of DEHSI. Bayley Scales of Infant Development-II, presence of cerebral palsy, and neurosensory impairment between 18 and 24 months of age were compared between the two groups. The associations of MR findings of other white matter lesions (cystic encephalomalacia, punctate lesions, loss of volume, ventricular dilatation, and delayed myelination) and subsequent outcomes were also analyzed. Outcome data were evaluated by using exact logistic regression analyses and Fisher exact test. RESULTS: DEHSI was present in 75% (95 of 126) of infants. Subsequent neurodevelopmental outcomes did not differ significantly between the two groups. Severe motor delay and cerebral palsy were more common in infants with both DEHSI and other white matter lesions as compared with infants with normal white matter (P = .001 and P < .001, respectively). Among other white matter lesions, cystic encephalomalacia (odds ratio, 19.6; 95% confidence interval: 1.3, 333.3) and punctate lesions (odds ratio, 90.9; 95% confidence interval: 6.4, 1000) were significant predictors of cerebral palsy. CONCLUSION: Although the incidence of DEHSI was high (75%) in preterm infants at near-term-equivalent age MR imaging, DEHSI was not predictive of following adverse outcomes. Cystic encephalomalacia and punctate lesions were more significant predictors of cerebral palsy.

Diffusion and perfusion characteristics of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episode) in thirteen patients.

OBJECTIVE: We analyzed the diffusion and perfusion characteristics of acute MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episode) lesions in a large series to investigate the controversial changes of the apparent diffusion coefficient (ADC) that were reported in prior studies. MATERIALS AND METHODS: We analyzed 44 newly appearing lesions during 28 stroke-like episodes in 13 patients with MELAS. We performed a visual assessment of the MR images including the ADC and perfusion maps, comparison of the ADC between the normal and abnormal areas, comparison of % ADC between the 44 MELAS lesions and the 30 acute ischemic infarcts. In addition, the patterns of evolution on follow-up MR images were analyzed. RESULTS: Decreased, increased, and normal ADCs were noted in 16 (36%), 16 (36%), and 12 (27%) lesions, respectively. The mean % ADC was 102 ± 40.9% in the MELAS and 64 ± 17.8% in the acute vascular infarcts (p < 0.001), while perfusion imaging demonstrated hyper-perfusion in six acute MELAS lesions. On follow-up images, resolution, progression, and tissue loss were noted in 10, 4, and 17 lesions, respectively. CONCLUSION: The cytotoxic edema gradually evolves following an acute stroke-like episode in patients with MELAS, and this may overlap with hyper-perfusion and vasogenic edema. The edematous swelling may be reversible or it may evolve to encephalomalacia, suggesting irreversible damage.

Comparison of clinico-radiological features between congenital cystic neuroblastoma and neonatal adrenal hemorrhagic pseudocyst.

OBJECTIVE: To evaluate the radiological and clinical findings of congenital cystic neuroblastomas as compared with those of the cystic presentation of neonatal adrenal hemorrhage. MATERIALS AND METHODS: We analyzed the US (n = 52), CT (n = 24), and MR (n = 4) images as well as the medical records of 28 patients harboring congenital cystic neuroblastomas (n = 16) and neonatal adrenal hemorrhagic pseudocysts (n = 14). The history of prenatal detection, location, size, presence of outer wall enhancement, internal septations, solid portion, calcification, turbidity, vascular flow on a Doppler examination, and evolution patterns were compared in two groups of cystic lesions, by Fischer's exact test. RESULTS: All (100%) neuroblastomas and three (21%) of the 14 hemorrhagic pseudocysts were detected prenatally. Both groups of cystic lesions occurred more frequently on the right side; 11 of 16 (69%) for neuroblastomas and 11 of 14 (79%) for hemorrhagic pseudocysts. The size, presence of solid portion, septum, enhancement, and turbidity did not differ significantly (p > 0.05) between the two groups of cystic lesions. However, tiny calcifications (n = 3) and vascular flow on color Doppler US (n = 3) were noted in only neuroblastomas. The cystic neuroblastomas became complex solid and cystic masses, and did not disappear for up to 90 days in the three following cases, whereas 11 of the 14 (79%) hemorrhagic pseudocysts disappeared completely and the three remaining (27%) evolved to calcifications only. CONCLUSION: Although the imaging findings of two groups of cystic lesions were similar, prenatal detection, the presence of calcification on initial images, vascularity on color Doppler US, and evolution to a more complex mass may all favor neuroblastomas.

Imaging characteristics of pilomyxoid astrocytomas in comparison with pilocytic astrocytomas.

PURPOSE: Pilomyxoid astrocytoma (PMA) is a recently described astrocytic tumor that has been previously diagnosed as pilocytic astrocytoma (PA). The purpose of this study was to describe the imaging features of PMAs in comparison with PAs. MATERIALS AND METHODS: We retrospectively reviewed CT/MR images and medical records of 10 patients with PMA and 38 patients with PA. The mean ages of patients with PMA and PA were 10 and 15 years, respectively. Imaging features including location, composition, enhancement pattern, presence of calcification, hemorrhage, and leptomeningeal dissemination were compared in patients with two tumor types. RESULTS: Six PMAs (60%) occurred at the suprasellar area and the cerebellum was the most common (45%) site of PA. Solid component was dominant in eight PMAs (80%) and in 19 PAs (50%). All of the PMAs containing solid mass (n=8) included non-enhancing portion while 12/37 (32%) PAs included non-enhancing solid portion (p<0.05). Leptomeningeal dissemination was noted in five PMAs (50%) and one PA (3%) (p<0.05). Other imaging findings were not significantly different. CONCLUSION: A younger age, more frequent occurrence at the suprasellar area, mainly solid mass containing non-enhancing portion, and more frequent leptomeningeal dissemination are helpful differential features of PMAs as compared to PAs.

Partially unroofed coronary sinus: MDCT and MRI findings.

OBJECTIVE: The purpose of this study was to analyze the MDCT and MRI findings in patients with unroofed coronary sinus syndrome. MATERIALS AND METHODS: This retrospective study included 11 patients with unroofed coronary sinus syndrome (10 adults, one child) without persistent left superior vena cava and one adult with communication of the left atrium and coronary sinus via an anomalous vein (unroofed coronary sinus variant). Four patients underwent contrast-enhanced ECG-gated MDCT; six, MRI; and two patients, both CT and MRI. We also measured the coronary sinus on the CT scans of 28 adults with normal cardiac anatomy and 10 adults with persistent left superior vena cava and compared the measurements with those in the patients with unroofed coronary sinus syndrome. Seven patients underwent surgical treatment of unroofed coronary sinus syndrome. RESULTS: At echocardiography, unroofed coronary sinus syndrome was not clearly discriminated from atrial septal defect in two patients and was not suspected in three patients. CT and MRI showed that 11 patients had a defect in which the coronary sinus communicated with the left atrium and that the other patient had atresia of the coronary sinus orifice with an anomalous vein connecting the coronary sinus and left atrium. In patients with unroofed coronary sinus syndrome, the mean standardized diameter of the coronary sinus according to the patient's body surface area was 15 ± 4 mm/m², similar to that of the control group with persistent left superior vena cava (15 ± 6 mm/m²; p = 0.97) and significantly greater than that of the group with normal cardiac anatomy (7 ± 2 mm/m²; p < 0.0001). CONCLUSION: CT and MRI facilitate definite diagnosis of unroofed coronary sinus syndrome.

Posttransplantation lymphoproliferative disorder in children: manifestations in hematopoietic cell recipients in comparison with liver recipients.

PURPOSE: To compare the clinical and imaging features of posttransplantation lymphoproliferative disorder (PTLD) in pediatric patients who underwent hematopoietic cell transplantation with those in pediatric patients who underwent liver transplantation. MATERIALS AND METHODS: This study was approved by the institutional review board, and the requirement to obtain informed consent was waived. The authors retrospectively reviewed the medical records and images of 552 hematopoietic cell transplant recipients and 195 liver transplant recipients. PTLD was histopathologically confirmed in 17 of the patients who underwent hematopoietic cell transplantation and 27 of the patients who underwent liver transplantation. The overall frequency, clinical course, histopathologic type, and imaging findings of PTLD were compared between the two patient groups by using the Fisher exact test. RESULTS: The overall frequency of PTLD was 3% (17 of 552 patients) after hematopoietic cell transplantation (12% [nine of 75 patients] after umbilical cord blood transplantation) and 14% (27 of 194 patients) after liver transplantation. PTLD occurred within 6 months of transplantation in 14 of the 17 hematopoietic cell recipients (82%) and 11 of the 27 liver recipients (41%) (P = .012). Histopathologic examination revealed monomorphic disease in 11 of the 17 hematopoietic cell recipients (65%) and eight of the 27 liver recipients (30%) (P = .031). The abdomen was the most common site of involvement in both groups. Extraabdominal PTLD developed in 12 of the 17 hematopoietic cell recipients (71%) and five of the 27 liver recipients (19%) (P = .002). Although 15 of the 17 patients with hematopoietic cell transplantation-related PTLD (88%) exhibited responses after treatment, the overall mortality rate was 35% (six of 17 patients). All 27 patients with PTLD after liver transplantation improved after treatment and remain alive. CONCLUSION: PTLD after umbilical cord blood transplantation occurred as frequently as liver transplantation-related PTLD. Compared with liver transplantation-related PTLD, PTLD after hematopoietic cell transplantation is characterized by an earlier onset, a higher proportion of malignant monomorphic disease, and a worse outcome.

Multimodality Imaging of Pediatric Parotid Gland Lesions

Although diseases of the parotid gland are relatively uncommon in children, a variety of benign and malignant lesions may occur and the use of imaging is essential for accurate diagnosis and treatment. Ultrasonography (US) is the initial imaging modality utilized for suspected parotid lesions, and its use may suggest a correct diagnosis in an adequate clinical setting. The use of computed tomography (CT) and magnetic resonance imaging (MRI) are useful for the assessment of large and atypical lesions. These modalities also allow the ability to image the deep parotid lobe and to better define the nature of a lesion. CT is the preferred imaging modality for inflammatory processes, including suspected sialolithiasis, abscesses and salivary duct obstructions, whereas MRI is usually used to evaluate tumors due to excellent anatomic resolution and a lack of ionizing radiation exposure, especially in children. This report describes the imaging findings of various parotid gland lesions in children. Familiarity with these findings will aid in lesion characterization and should facilitate optimal clinical management.

Serial CT findings of Paragonimus infested dogs and the Micro-CT findings of the worm cysts.

OBJECTIVE: To investigate the serial CT findings of Paragonimus westermani infected dogs and the microscopic structures of the worm cysts using Micro-CT. MATERIALS AND METHODS: This study was approved by the committee on animal research at our institution. Fifteen dogs infected with P. westermani underwent serial contrast-enhanced CT scans at pre-infection, after 10 days of infection, and monthly thereafter until six months for determining the radiologic-pathologic correlation. Three dogs (one dog each time) were sacrificed at 1, 3 and 6 months, respectively. After fixation of the lungs, both multi-detector CT and Micro-CT were performed for examining the worm cysts. RESULTS: The initial findings were pleural effusion and/or subpleural ground-glass opacities or linear opacities at day 10. At day 30, subpleural and peribronchial nodules appeared with hydropneumothorax and abdominal or chest wall air bubbles. Cavitary change and bronchial dilatation began to be seen on CT scan at day 30 and this was mostly seen together with mediastinal lymphadenopathy at day 60. Thereafter, subpleural ground-glass opacities and nodules with or without cavitary changes were persistently observed until day 180. After cavitary change of the nodules, the migratory features of the subpleural or peribronchial nodules were seen on all the serial CT scans. Micro-CT showed that the cyst wall contained dilated interconnected tubular structures, which had communications with the cavity and the adjacent distal bronchus. CONCLUSION: The CT findings of paragonimiasis depend on the migratory stage of the worms. The worm cyst can have numerous interconnected tubular channels within its own wall and these channels have connections with the cavity and the adjacent distal bronchus.

Hepatic radiofrequency ablation using multiple probes: ex vivo and in vivo comparative studies of monopolar versus multipolar modes.

OBJECTIVE: We wanted to compare the efficiency of multipolar radiofrequency ablation (RFA) using three perfused-cooled electrodes with multiple overlapping and simultaneous monopolar techniques for creating an ablation zone in ex vivo bovine livers and in in vivo porcine livers. MATERIALS AND METHODS: In the ex vivo experiments, we used a 200 W generator (Valleylab, CC-3 model) and three perfused-cooled electrodes or internally cooled electrodes to create 30 coagulation zones by performing consecutive monopolar RFA (group A, n = 10), simultaneous monopolar RFA (group B, n = 10) or multipolar RFA (group C, n = 10) in explanted bovine livers. In the consecutive mode, three ablation spheres were created by sequentially applying 150 watts radiofrequency (RF) energy to the internally cooled electrodes for 12 minutes each for a total of 36 minutes. In the simultaneous monopolar and multipolar modes, RF energy was concurrently applied to the three perfused-cooled electrodes for 20 minutes at 150 watt with instillation of 6% hypertonic saline at 2 mL/min. During RFA, we measured the temperatures of the treated area at its center. The changes in impedance, the current and liver temperature during RFA, as well as the dimensions of the thermal ablation zones, were compared among the three groups. In the in vivo experiments, three coagulations were created by performing multipolar RFA in a pig via laparotomy with using same parameter as the ex vivo study. RESULTS: In the ex vivo experiments, the impedance was gradually decreased during the RFA in groups B and C, but in group A, the impedance was increased during RFA and this induced activation by the pulsed RF technique. In groups A, B and C, the mean final-temperature values were 80+/-10 degrees C, 69+/-18 degrees C and 79+/-12 degrees C, respectively (p < 0.05). The multipolar mode created a larger volume of ablation than did the other modes: 37.6+/-4.0 cm3 (group A); 44.9+/-12.7 cm3 (group B); and 78.9+/-6.9 cm3 (group C) (p < 0.05). In the in vivo experiment, the pig well tolerated the RFA procedure and no major complications occurred during the 4 days of the follow-up period. The mean volume of coagulations produced by multipolar RFA in the pig liver was 60.5+/-17.9 cm3. CONCLUSION: For the multiple probe RFA, the multipolar mode with hypertonic saline instillation was more efficient in generating larger areas of thermal ablation than either the consecutive or simultaneous monopolar modes.