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Vascular injury is increasingly recognized as an important cause of mortality and morbidity in children (29 days to 18 years of age). Since vascular brain injury in children appears to be less common than in adults, the index of suspicion for vascular brain injury is usually lower. In this review article, we describe frequent and rare conditions underlying pediatric stroke including cardioembolic, viral, autoimmune, post-traumatic, and genetic etiologies. Furthermore, we provide a neuroimaging correlate for clinical mimics of pediatric stroke. This review highlights the role of multimodal noninvasive neuroimaging in the early diagnosis of pediatric stroke, providing a problem-solving approach to the differential diagnosis for the neuroradiologist, emergency room physician, and neurologist.

Background and Purpose: Iterative reconstruction techniques facilitate CT dose reduction; though to our knowledge, no group has explored using iterative reconstruction with pediatric head CT. Our purpose was to perform a feasibility study to assess the use of ASIR in a small group of pediatric patients undergoing head CT., Materials and Methods: An Alderson-Rando head phantom was scanned at decreasing 10% mA intervals relative to our standard protocol, and each study was then reconstructed at 10% ASIR intervals. An intracranial region of interest was consistently placed to estimate noise. Our ventriculoperitoneal shunt CT protocol was subsequently modified, and patients were scanned at 20% ASIR with approximately 20% mA reductions. ASIR studies were anonymously compared with older non-ASIR studies from the same patients by 2 attending pediatric neuroradiologists for diagnostic utility, sharpness, noise, and artifacts., Results: The phantom study demonstrated similar noise at 100% mA/0% ASIR (3.9) and 80% mA/20% ASIR (3.7). Twelve pediatric patients were scanned at reduced dose at 20% ASIR. The average CTDI(vol) and DLP values of the 20% ASIR studies were 22.4 mGy and 338.4 mGy-cm, and for the non-ASIR studies, they were 28.8 mGy and 444.5 mGy-cm, representing statistically significant decreases in the CTDI(vol) (22.1%, P = .00007) and DLP (23.9%, P = .0005) values. There were no significant differences between the ASIR studies and non-ASIR studies with respect to diagnostic acceptability, sharpness, noise, or artifacts., Conclusions: Our findings suggest that 20% ASIR can provide approximately 22% dose reduction in pediatric head CT without affecting image quality.

Objective: Wernicke's encephalopathy is an acute neurological syndrome resulting from thiamine (vitamin B1) deficiency. Early recognition is important because timely thiamine supplementation can reverse the clinical features of the disease. The aim of this article is to provide an update on the typical and atypical neuroimaging findings of the acute phase of the disease., Conclusion: Wernicke's encephalopathy is characterized by a quite distinct pattern of MR alterations, which include symmetrical alterations in the thalami, mamillary bodies, tectal plate, and periaqueductal area, but atypical alterations may also been seen. A thorough knowledge of the neuroimaging findings of Wernicke's encephalopathy will assist in arriving at an early diagnosis, thus reducing the morbidity and mortality associated with this disease.

Peliosis hepatis is an uncommon benign disorder characterized by blood-filled cavities within the liver. We describe the sonographic, computed tomographic, and magnetic resonance appearance of a patient affected by peliosis hepatis with pseudotumoral and hemorrhagic evolution and direct demonstration of the ectatic vascular components.

This article reviews the CT imaging features of the most frequent mesenchymal tumors of the pancreas and stresses important distinctive patterns that may help distinguish specific entities. Various neoplasms (lymphangioma, lipoma, teratoma, pancreatoblastoma, schwannoma, neurofibroma, lymphoma, and sarcoma) are reviewed, with key differential points (structure, fatty and water densities, calcification, pattern of contrast enhancement, vascularization, and necrotic or regressive changes) emphasized. In addition, epithelial tumors are considered in the differential diagnosis.

We report a case of pseudotumoral involvement of the breast in Erdheim-Chester disease. CT shows an enlargement of both breasts with inhomogeneous structure, microcalcifications, and foci of fatty density.

Purpose: To describe CT findings of calcified renal metastases focusing on differential diagnosis problems., Material and Methods: We retrospectively reviewed abdominal CT scans of 8000 patients with tumor, performed from 1984 to 1998. Among the 58 renal metastases, 9 showed a calcific component. We evaluated the location, morphostructural pattern, histology of the primary lesion, the synchronous or metachronous character and the type of treatment. All the lesions were pathologically proved., Results: The primary histotype of the 9 metastases was as follows: 4 mucin-producing adenocarcinomas of the large bowel, 1 gastric mucinous adenocarcinoma, 1 chondrosarcoma, 1 osteosarcoma, 1 melanoma, 1 papillary thyroid carcinoma. In all the cases the renal metastasis was unilateral and unifocal. Granular multiple calcifications were demonstrated within the metastases of mucin-producing adenocarcinoma of the large bowel (3), within the metastasis of chondrosarcoma (1) and of melanoma (1). Diffuse "star-like" calcifications were demonstrated in renal metastases of mucin-producing adenocarcinoma of the large bowel and of gastric mucinous adenocarcinoma (1). Peripheral "egg-shell" calcifications were demonstrated in renal metastasis from papillary thyroid carcinoma (1). Completely calcified monofocal calcification was demonstrated in renal metastasis from osteosarcoma (1)., Discussion and Conclusions: Calcified renal metastases are rare lesions related to specific oncotypes. The differential diagnosis (carcinoma with calcifications, osteosarcoma, chondrosarcoma, nephrocalcinosis, granulomatosis, hydatidosis etc.) is particularly difficult because of the aspecificity of the morphostructural pattern. Diagnosis is based on a history of specific oncotypes (papillary and mucin-secreting carcinomas, osteosarcoma and chondrosarcoma), but in most cases it requires pathologic confirmation.

Purpose: Gastric stromal tumors are an ill-defined group of lesions arising from muscle wall cells and characterized by extremely variable biological patterns. Thanks to modern immunohistochemical and ultrastructural techniques, four main classes of these lesions have been identified, namely: 1) tumors with differentiation toward smooth muscle cells; 2) tumors with differentiation toward neural elements; 3) tumors with dual differentiation toward both cell types; 4) tumors lacking differentiation toward either cell type. We investigated the yield of CT in diagnosing and characterizing gastric stromal tumors., Material and Methods: We retrospectively reviewed the CT findings of 38 patients (15 men and 23 women; mean age 51 years) with pathologically proven gastric stromal tumors, namely 31 of myoid origin, 4 of neural origin, 2 with both muscle and neural differentiation, 1 lacking differentiation with either cell type. Morphological (size, margins, growth pattern, enlarged lymph nodes, metastases) and structural (density, calcifications, necrosis, cystic changes, enhancement patterns) parameters were evaluated and compared with histopathologic diagnosis., Results: The myoid tumors involved gastric fundus in 9/13 and 5/7 benign lesions and lesions with variable biological patterns, respectively, while the malignant tumors exhibited diffuse involvement in 7/11 of cases. Eleven of 13 benign lesions had regular shape and a diameter +/- 5 cm, while 5/7 intermediate tumors and 7/11 malignant ones were 6-10 cm and over 10 cm (1/7 and 3/11, respectively). Tumor growth was intramural (6/13) or mixed (5/13) in the benign lesions, mainly exophytic in the malignant ones, and finally variable (2/7 intramural, 3/7 exophytic and 2/7 mixed) in the tumors with intermediate patterns. Calcifications were identified only in 3 benign lesions. Structure was homogeneous in 11/13 of the benign lesions with regular contrast enhancement (10/12), heterogeneous due to necrotic areas in nearly all (10/11) or most (5/7) malignant and intermediate forms, respectively. Enlarged lymph nodes (4/11) or synchronous metastases (7/11) were found in the malignant lesions. Our two schwannomas had a pseudocystic structure with regular peripheral contrast enhancement; the neurofibroma was characterized by multiple, markedly hypodense and hypovascular lesions. Both the malignant neurogen form and the two tumors with dual differentiation showed a diffuse, aspecific and infiltrating pattern. The lesion without differentiation had a "benign" shape and structure even though it developed metastases two years after radical surgery., Conclusions: Despite the lack of specificity of CT patterns of gastric stromal tumors, these parameters are useful in differentiating benign from overtly malignant forms. The definition "gastric stromal tumor with benign, variable, or malignant macroscopic appearance" should be used in the radiologic report.

Purpose: Computed tomography (CT) and, more recently, ultrasound (US), have proved excellent tools for quantifying adipose tissue distribution. Body fat distribution is an important factor in the treatment of obesity and its complications. We investigated the correlation between CT and US measurements in pediatric obesity., Material and Methods: Forty obese children and adolescents aged 4.1-14.8 years were submitted to CT and US. Intra-abdominal, subcutaneous and total body fat were calculated (in cm2), with the CT image analysis software. The rectus muscle-spine and rectus muscle-aorta distances, as indicative of visceral fat thickness, were measured on US images with(out) compression. The distance between skin-fat and fat-rectus muscle interfaces was measured as subcutaneous fat thickness. We also compared US-CT findings with other morphometric variables--i.e., patient's (ideal) body weight and skin fold measures., Results: At US, the rectus muscle-aorta and rectus muscle-spine distances ranged 2.4-7.5 cm (mean: 4.47 cm) and 3.6-8.9 cm (mean: 5.79 cm), respectively. The skin-rectus muscle distance ranged 1.2-7.5 cm (mean: 3.14 cm). A statistically significant correlation was found between the CT measurement of visceral fat and the aorta-rectus muscle and rectus muscle-spine distances (r = 0.80 and 0.74, respectively). The US measurements of subcutaneous fat were correlated with CT subcutaneous fat area (r = 0.82). No correlation was found between overweight, as calculated by body mass index, and CT or US fat., Conclusion: Our findings indicate that US is as useful as CT in evaluating body fat distribution in pediatric obesity.

In 1995, as a result of the observation of Rhabdoid elements among the other components of a Teratoid/Rhabdoid tumor (TRT), a new nomenclature was introduced, Atypical Teratoid/Rhabdoid Tumor (ATRT) of infancy and childhood. We report the clinical history and radiological findings in a child affected by central nervous system (CNS) ATRT.

Purpose: To report the CT patterns of pancreatic mesenchymal lesions and to investigate the capabilities and limitations of this technique in terms of characterization., Material and Methods: We selected the CT examinations of 23 patients from all CT examinations of the pancreas performed from 1986 to 1998. The patients were 10 to 85 years old and all lesions but two (1 lipoma and 1 lymphoma) had pathologic confirmation. Two lymphangiomas, 2 lipomas, 4 Schwannomas (SCH), 1 plexiform neurofibroma, 1 cystic teratoma, 1 pancreatoblastoma, 9 non-Hodgkin's lymphomas (NHL), 1 undifferentiated sarcoma and 2 leiomyosarcomas were diagnosed., Results: Lipomas had typically homogeneous negative HU values, and NHL a homogeneous hypodense pattern with mild contrast enhancement, with no necrosis or calcifications in both diffuse and nodular forms; SCH had variable appearance, with water/slightly negative HU numbers or highly enhanced patterns with a central necrotic core depending on the main Antoni A or B histology. Lymphangiomas appeared as complex cysts, with thin and regular or calcified walls and intracystic septa, while the plexiform neurofibroma had near-water homogeneous density with mild contrast enhancement and an infiltrating growth pattern. Our teratoma had multiple calcifications, mucinous and lipid components. The pancreatoblastoma, sarcomas, and leiomyosarcomas exhibited no specific findings., Conclusions: In selected cases, CT can provide virtually diagnostic information (lipoma and teratoma), or at least highly suggestive findings (NHL, plexiform neurofibroma, lymphangioma). Moreover, knowledge of the variable morphostructural patterns of mesenchymal histotypes (SCH, sarcoma etc.) permits to include them in the differential diagnosis of pancreatic masses.