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Purpose: Spontaneous dissection of the carotid and vertebral arteries represents a rare pathology. Its pathogenesis, probably multi-factorial, can be related to neck trauma and to a genetic basis, extensively demonstrated in the cases of association with type IV fibromuscular dysplasia, Ehlers-Danlos syndrome, Marfan's syndrome, pseudoxanthoma elasticum and osteogenesis imperfecta. Onset symptoms include neck, facial pain and diffuse headache. Cranial nerve palsy has been also described. The aim of this study was to evaluate MR angiography and MR findings in a population of patients with carotid and vertebral artery dissections., Materials and Methods: We reviewed the MR angiography and MR exams of 15 patients (10 males, 5 females, average age 42.0, age range 30-55) with carotid and/or vertebral artery dissection; the serial MR follow-up studies were also examined., Results: Twelve internal carotid arteries (ICA) showed the presence of an irregular stenosis; three of these showed complete occlusion. In two patients both ICA were involved. Six vertebral arteries (VA) showed irregular stenosis (only one patient suffered from both CI and VA dissection); in one case there was also a pseudoaneurysm of the VA. Follow-up studies showed vessel lumen re-opening in 5/11 ICA (one patient underwent vascular stent positioning) and in 3/6 VA., Conclusions: The present study confirms the usefulness of MR angiography and MR in the diagnosis and follow-up of patients with carotid and vertebral artery dissection.

Purpose: To evaluate a patient population affected by Neurofibromatosis type 1 (NF1) with special reference to optic pathway gliomas., Material and Methods: A total of 419 NF1 patients (222 men, 197 women) were retrospectively evaluated to show incidence, biological behaviour, neuroradiological and clinical presentation of optic pathway gliomas. Central Nervous System MR and ophthalmologic evaluations were reviewed., Results: Thirty-two patients out of 419 (7.6%) showed the presence of optic pathway gliomas. Of these, 28 (87.2%) patients showed tumoral involvement of the optic chiasma. The right intracranial optic nerve was involved in 15 patients (46.8%), the left intracranial optic nerve in 18 (56.2%), the right extracranial optic nerve in 11 (34.3%), the left extracranial optic nerve in 10 (31.2%) and the right and left optic tracts in 6 (18.7%) patients. Geniculate body and optic radiation were not involved by tumour diffusion. Visual acuity testing was positive in 26/32 (81.2%), the fundus oculi in 11/32 (34.3%) patients and the visual field evaluation in 12/32 (37.5%) patients., Conclusions: In this study we showed an high correlation between optic pathway tumours and ophthalmologic abnormalities confirming the usefulness of an integrated clinical-neuroradiological approach in patients affected by NF1. We also described the biological behaviour of these tumours in our NF1 patient population.

Purpose: To investigate the relationship between Magnetic Resonance (MR) findings and the presence of isolated growth hormone deficiency (IGHD) or multiple pituitary hormone deficiency (MPHD)., Material and Methods: 39 children, 27 boys and 12 girls (mean age 9.6 years) were enrolled. The growth hormone deficiency and MPHD were defined by standard laboratory methods. MR scans of the hypothalamo-hypophyseal tract were carried out on all patients before the therapy. Perinatal histories were reviewed., Results: The pituitary anterior lobe was considered small in 13/39 (33%). Twenty-six of 39 (66%) patients did not show any abnormalities of the hypothalamohypophyseal tract. An ectopic neurohypophysis was found in 8/39 patients (20%). Only 2 patients among those with an ectopic neurohypophysis showed a small anterior pituitary lobe. Thirty-three of 39 (84.6%) patients showed IGHD while 6/39 (15.4%) patients showed MPHD. Twenty-eight of 39 (71%) patients had a severe deficiency while 11/39 (28%) patients had a moderate deficiency., Conclusion: Our study confirms the usefulness of MRI in the diagnostic and therapeutic approach to short stature in children; in fact 48% of patients in our series showed MR findings reasonably related to hormonal deficiency.

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.

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.

Purpose: To analyze the extracerebral manifestations of type 1 neurofibromatosis (NF-1), with special reference to peripheral nerve tumors., Material and Methods: The findings of 376 NF-1 patients (194 men and 182 women; age range: 0.1-48 years, mean: 8.1) were retrospectively reviewed. The patients had been submitted to abdominopelvic and superficial US and, in case of abnormal US findings or in the presence of symptoms, to CT and/or MRI. In addition, we considered 5 more patients (2 men and 3 women; age range: 50-72 years, mean: 64.4) with incomplete forms of NF-1 diagnosed after the finding of nerve sheath tumors. Biopsy (12 cases), surgery (10 cases), or clinical-instrumental follow-up were the study criteria., Results: In the first group of patients we identified 91 cutaneous, 222 subcutaneous, 11 pendulous and 25 internal neurofibromas. Plexiform neurofibromas were found in the neck (1 case), chest (6 cases), abdomen (16), pelvis (8). We also found 1 benign and 1 malignant Schwannomas, 2 nerve sheath fibrosarcomas, 1 dopamine-producing sympatoma and 1 spermacytoma. As for the second group of patients, we had 2 Schwannomas, 1 pulmonary neurofibroma, and 2 multiple plexiform neurofibromas. The neurofibromas exhibited homogeneous US hypoechogenicity or slight echogenicity, with little contrast enhancement at CT. MR showed peripheral hyperintensity and central hypointensity on T2-weighted sequences and marked contrast enhancement after gadolinium, sometimes with mostly central uptake. The plexiform neurofibromas, which are typical of NF-1, had poorly-defined or infiltrating margins, with similar findings to the previous ones but sometimes with less homogeneous patterns at both US and CT. The Schwannomas, which are a less common finding in NF-1, exhibited different features at MRI and CT, namely pseudo-liquid or solid-inhomogeneous patterns with irregular and inhomogeneous contrast enhancement relative to the Antoni A/B tumor component. In the malignant lesions we observed infiltrating patterns, with irregular and inhomogeneous contrast enhancement, arranged asymmetrically relative to the contralateral lesion., Conclusions: Extra-axial neoplasms are a frequent finding in NF-1. Despite the extremely variable appearances of some lesions (particularly Schwannomas), the typical plexiform neurofibroma exhibits characteristic patterns. The diagnosis of malignancy often requires bioptic confirmation.