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Congenital absence of the portal vein (CAPV) is a rare malformation in which intestinal and splenic venous flow bypasses the liver and drains directly into the systemic circulation via a congenital portosystemic shunt. We describe two cases of CAPV presenting as pulmonary hypertension that were initially suspected as primary pulmonary hypertension. However, subsequent ultrasonography and CT detected the absence of a portal vein and the presence of a portosystemic shunt. Pulmonary hypertension is a recognized complication of liver disease and portal hypertension. However, these two cases illustrate that CAPV may result in pulmonary hypertension without liver disease or portal hypertension.

Purpose: We reviewed the distribution of lesion and the characteristics of the MR findings of acute disseminated encephalomyelitis (ADEM) in children. We evaluated the differences in the imaging findings and the clinical outcomes between the patients with deep gray matter involvement and the patients without deep gray matter involvement. Materials and Methods: We retrospectively reviewed the 62 MR examinations of 21 patients who were discharged with the clinical diagnosis of ADEM. The patients were aged from 13 months to 12 years old (mean age: 4.5 years). Follow-up MR examinations were done one to 5 times (mean: 3 times) for 2 weeks to 4 years (mean: 3 months) after the initial examination. We compared the signal intensity on T2WI, the enhancement and residue on the MR images and the clinical outcomes between the patients with deep gray matter involvement and the patients without deep gray matter involvement. Results: A total of 21 patients had white matter abnormalities on their initial MR. Fifteen patients (71%) had foci of increased signal intensity on T2WI in the deep gray matter: thalamus (n=15), globus pallidus (n=14) and putamen (n=10). On the followup images, all patients showed decreased signal intensity and enhancement of their lesion. We could not find the significant differences in signal intensity, enhancement and residue on the MRIs and also the clinical outcomes between the patients with deep gray matter involvement and the patients without deep gray matter involvement (

Metanephric adenoma is a rare tumor of the kidney that has been reported mostly in adults. Despite its rarity, metanephric adenoma should be included in any differential diagnosis of solid renal masses in children, especially because of its benign nature and benign clinical course allowing for nephron sparing surgery. We report a case of metanephric adenoma, presented as a solid renal mass in a 14-month-old boy, and discuss the histologic basis of the imaging features of this entity.

Purpose: The purpose of this study was to analyze the enhancement pattern of the spinal cord for patients with medulloblastoma, and to correlate the enhancement pattern with cerebrospinal fluid (CSF) tumor seeding. Materials and Methods: We retrospectively reviewed 84 MR images, including the initial and follow-up studies after chemotherapy or radiation therapy, of 25 patients with medulloblastoma who were aged from 2 to 13 years. We analyzed the spinal leptomeningeal enhancement pattern on the MR images. The leptomeningeal enhancement patterns were categorized into three types: Type I, fine or discontinuous linear enhancement, and type II, continuous linear or nodular enhancement, and type III, intradural mass formation. We correlated the enhancement pattern on MRI with the results of CSF cytology at the initial and follow - up examinations after treatment. Results: Of total 25 patients, type I enhancement was observed for 14 patients. Twelve patients were negative on the initial CSF cytology and 2 patients were positive. On the follow-up MR studies, 14 patients showed no change or only a slight decrease of enhancement, and all were negative on the follow-up CSF cytology. Type II enhancement patterns were observed in seven patients, and all of them were positive on the initial CSF cytology. On follow-up MR study, one patient revealed an increased enhancement with the positive result on the follow-up CSF cytology, and six patients had decreased enhancement on the follow-up MR studies with negative conversion on the follow-up CSF cytology. Type III enhancement patterns were observed in four patients and all of them were positive on the initial CSF cytology. All four patients with intradural mass formations revealed progression of the lesions on follow-up MR studies, and all of them were positive on the follow-up CSF cytology. Conclusion: Type II and III enhancement patterns always represented CSF seeding and a type I enhancement pattern had a low probability of metastasis.

Purpose: To assess the high-resolution CT (HRCT) findings of small airway abnormalities after mycoplasma pneumonia and correlate them with the findings of chest radiography performed during the acute and follow-up phases of the condition. Materials and Methods: We retrospectively evaluated HRCT and chest radiographic findings of 18 patients with clinical diagnosis of small airway disease after mycoplasma pneumonia (M:F=8:10, mean age: 8.3 years, mean time interval after the initial infection; 26 months). We evaluated the lung parenchymal and bronchial abnormalities on HRCT (n=18). In addition, presence of air-trapping was assessed on expiratory scans (n=13). The findings of HRCT were correlated with those of chest radiography performed during the acute phase of initial infection (n=15) and at the time of CT examination (n=18), respectively. Results: HRCT revealed lung parenchymal abnormalities in 13 patients (72%). A mosaic pattern of lung attenuation was noted in ten patients (10/18, 56%), and air-trapping on expiratory scans was observed in nine (9/13, 69%). In nine of 14 (64%) with negative findings at follow-up chest radiography, one or both of the above parenchymal abnormalities was observed at HRCT. In four patients (27%), parenchymal abnormalities were seen at HRCT in areas considered normal at acute-phase chest radiography. Bronchiectasis or ateclectasis was observed in eight (44%) and four (22%) patients, respectively, at HRCT. The CT features of Swyer-James syndrome such as a unilateral hyperlucent lung with reduced lung volume and attenuated vessels were noted in two patients (11%). Conclusion: HRCT can clearly demonstrate lung parenchymal and bronchial abnormalities of small airway disease after mycoplasma pneumonia in children.

Purpose: Endoscopic incision of ureterocele is considered a simple and safe method for decompression of uri-nary tract obstruction above ureterocele. The purpose of this study was to evaluate the radiological findings af-ter endoscopic incision of ureterocele.Materials and Methods: We retrospectively reviewed the radiological findings [ultrasonography (US), intra-venous urography, and voiding cystourethrography(VCU)] in 16 patients with ureterocele who underwent endoscopic incision (mean age at surgery, 15 months; M: F=3:13; 18 ureteroceles). According to the postoperative results, treatment was classified as successful when urinary tract obstruction improved without additional treatment, partially successful when medical treatment was still required, and second operation when addi-tional surgical treatment was required.Results: Postoperative US (n=10) showed that in all patients, urinary tract obstruction was relieved: the kid-ney parenchyma was thicker and the ureterocele was smaller. Intravenous urography (n=8), demonstrated that in all patients, urinary tract obstruction and the excretory function of the kidney had improved. Postoperative VCU indicated that in 92% of patients (12 of 13), endoscopic incision of the ureterocele led to vesicoureteral reflux(VUR). Of these twelve, seven (58%) showed VUR of more than grade 3, while newly developed VUR was seen in five of eight patients (63%) who had preoperative VCU. Surgery was successful in four patients (25%), partially successful in three (19%), and a second operation-on account of recurrent urinary tract infection and VUR of more than grade 3 during the follow-up period-was required by nine (56%).Conclusion: Although endoscopic incision of a ureterocele is a useful way of relieving urinary tract obstruction, an ensuing complication may be VUR. Postoperative US and intravenous urography should be used to evaluate parenchymal change in the kidney and improvement of urinary tract obstruction, while to assess the extent of VUR during the follow-up period, postoperative VCU is required.

Purpose: To evaluate the MR findings of a development of bony bridge within tunnels drilled across growth plates after injury in immature rabbits, and to correlate the MR and pathological findings. Materials and Methods: In 19 young rabbits, a growth-plate injury model was constructed in the distal femur by longitudinal drilling with a 5-mm drill. Coronal scans with T1-weighted, T2-weighted fast spin-echo, gradient echo, and gadolinium enhanced T1-weighted sequences were obtained immediately, and at 1, 2, 3, and 4 weeks, and 3, 6 months, postoperatively. Each group underwent pathologic examination, and the signal inten-sity, shape, and enhancement pattern of the drill holes were assessed. All results were correlated with pathologic findings. Results: During the early period, the signal intensity of the defect site varied due to hemorrhage and inflammatory reaction in the lesion, becoming isointense to that of metaphyseal marrow on all sequences during the late period (3 and 6 months). Pathologically, it corresponded to replacement of the osseous bridge with fatty marrow. The new bone formation shown by pathologic examination to be present in the periphery of the defect during the first week corresponded to the vertical dark rim seen on MR images. It appeared during that week and became more distinct, thickening gradually until the fourth week. Enhancement was absent or faint on follow-up immediately after surgery, inhomogenous and seen in half the rabbits at week 1, and maximal and homogenous at weeks 2 and 3. In had decreased by week 4, and was absent at months 3 and 6. These findings corresponded to the changes in transphyseal vascularity across the drill hole revealed by pathologic examination. Conclusion: The contrast enhancement demonstrated by defective growth plate may indicate the develop-ment of vascularity throughout the plate, a phenomenon which precedes the formation of a bony bridge after trauma.

Purpose :To determine by means of MR imaging the ischemic status of parenchymal lesions in moyamoya disease. Materials and Methods : Ninety-two MR images in 50 children with moyamoya disease were retrospectively reviewed. Ischemic parenchymal lesions were categorized according to the signal intensities of cortex and subcortical white matter. We also analyzed enhancement patterns, time sequential changes in the lesions, and the Prognosis for each patient, according to lesion type. Results : Among one hundred and seventeen parenchymal abnormalities, 89 gyral lesions were seen in 43 children (86 %), predominantly in the frontal area (33.1%). Cortical parenchymal lesions were categorized as either type I - intermediate to high signal intensity (SI) on both T2 weighted (T2WI) and proton density images(PDI), and associated with low SI of the subcortical white matter; type II - high SI on T2WI and PDI, without low SI of the subcortical white matter; or type III - high SI on T2WI and iso SI on PDI. Thirty-three lesions were type I, ten were type II, and 43 were type III. Time sequential changes from type I to type II, and then to type III, were observed. The prognoses of patients with a type-I lesion were better than those of patients whose lesions were type II or III. Conclusion : Type I lesions presented with abnormal low signal intensity in the subcortical white matter, as seen on T2W1 images. This was the characteristic and earliest finding of ischemic parenchymal lesions in moyamoya disease; sequential MR images showed that type-I lesions progressed to type II or III.

Purpose : The Purposes of this article are to illustrate the typical imaging features of eight patients with this syndrome and to discuss the advantage of each imaging modality with a concise review of literatures.Materials and Methods: We retrospectively reviewed plain skull radiographs(6). computd tomographic(CT) scans(8), magnetic resonnance(MR ) images(4)and cerebral angiograms(3) of eight patients with Sturge-Weber syndrome. We analyzed the radiographic finding of Sturge -Weber syndrome and compared the findings of CT, MR and angiography.Results : Plain radiographs showed characteristic gyriform calcifications(3)after 2 years of age. CT scans excellently demonstrated cortical calcifications(5),prominently enhancing choroid plexi(5) and dilated periventricular veins(2) . MR revealed dilated deep cerebral veins as tubular or spot- like signal void structures at periventricular areas(3) and showed stripes of cortical enhancement after gadolinium infection(2). Angiography showed dilated tortuous medullary and deep cerebral veins(3) as the collateral pathways of blood shunting. MR was superior to CT in the detection of parenchymal atrophy. venous abnormalities and the extent of angiomatous involvement. Angiography showed enlarged deep cerebral or medullary veins better than MR imaging.Conclusion : We think that each imaging modality including CT, MR or angiography has unique advantages in the diagnosis of this syndrome but MR will be used frequently because of its superior ability for the detection of atrophy, vascular abnormalities and direct visualization of leptomeningeal angiomatosis with contrast enhancement .