Oğuzhan Özdemir

Mesenteric involvement in neurofibromatosis type 1: CT and MRI findings in two cases

We report computerized tomographic and magnetic resonance imaging findings of neurofibromatosis type 1 with mesenteric involvement in two patients. The first patient was a 13-year-old female with a panmesenteric plexiform neurofibroma with segmental involvement of the bowel wall; she had a 3-year history of abdominal pain. The second patient was a 60-year-old female who presented with malignant transformation of multiple mesenteric neurofibromas 4 months after primary operation.

Intra-axial epidermoid cysts of the brainstem.

An 18-year-old male with one year history of cervical pain was admitted to our hospital without any significant neurological deficit. CT revealed a hypodense, non-enhancing mass in the center of the pons. On T1-weighted images, we noted that the extraaxial and central intra-axial parts of the mass were hyperintense compared to the brain parenchyma. The peripheral portion of the lesion was hypointense (figure 1a). On T2-weighted images the lesion was predominantly hyperintense with minimal central hypointensity (figure 1b). The peripheral rim of the lesion was slightly more hyperintense corresponding to the hypointensity of T1 images that represented the trapped cerebrospinal fluid (CSF). The mass was predominanty intra-axial with slight extension to the prepontine cistern. No enhancement was seen after paramagnetic contrast administration. Both diffusion-weighted imaging (DWI) and fluid-attenuated inversion-recovery (FLAIR) images demonstrated a hyperintense mass in the pons, thus differentiating the lesion from an arachnoid cyst. The lesion was excised and the histopathological diagnosis was epidermoid tumor. Brainstem epidermoids are rare, and to our knowledge less than 20 cases have been reported in the literature to date [2, 5]. Epidermoid cysts occur due to aberration of epithelial rests or sequestration of ectodermal elements at an early developmental stage, between the 3th and 5th weeks of gastation. There are two supposed mechanisms about the occurence of these tumors in a midline position within intraparenchymal and extra-axial, respectively: 1. proliferation of multipotential embryonic cells, and 2. lateral displacement of primitive ectodermal remnants along the developing otic vesicles or neurovascular structures. Our case most probably fits to the second hypothesis by insinuating of the cyst from prepontine region into the pons [1]. Most epidermoid cysts show a distinctive MR imaging appearance consisting of an irregularly shaped lesion having slightly higher signal intensity than CSF on T1, T2 and proton density-weighted images, with a characteristic marbled inner pattern on T1-weighted images [7, 9]. In a study of literature review [6], MR features of 10 patients with intraparenchymal epidermoid cysts were summarized as follows: 7 (70%) were low intensity on T1 and high intensity on T2, 2 (20%) were high intensity on T1 and low intensity on T2, and 1 (10%) was low intensity on T1 without data on T2 weighted spin echo images. To our knowledge of the literature, our case is unique in being largely hyperintense on both T1and T2-weighted images. This is probably the result of abundant cholesterol crystals and fatty components. Various MR imaging sequences have been proposed for the diagnosis of epidermoid cysts including DWI and FLAIR. When epidermoid cysts show a CSF-like signal on conventional spin-echo images, differentiation from an arachnoid cyst can be done using DW imaging, as these lesions have restricted diffusion with lower apparent diffusion coefficient values [3, 8, 10]. FLAIR has been shown to be extremely helpful in making the discrimination between arachnoid cyst, which contains CSF, and epidermoids, which do not and therefore hyperintense on FLAIR [4].

Multi‐Slice Computed Tomography Urography After Diuretic Injection in Children with Urinary Tract Dilatation

Purpose: To evaluate the potential use of multi‐slice computed tomography urography (MSCTU) after diuretic injection in children with urinary tract dilatation. Material and Methods: MSCTU was performed in 19 patients (11 boys, 8 girls, mean age 5.4 years) with suspicion of urinary tract obstruction and dilatation. Furosemide, 1 mg/kg, was injected 3 min before contrast material administration and followed by a bolus of 30 ml of physiologic saline solution immediately after application of contrast material. Excretory‐phase images were obtained through the abdomen and pelvis beginning 10 min after initiation of the injection of contrast material. Maximum intensity projection (MIP) and volume rendering (VR) images were post‐processed to obtain urographic views. Results: MSCTU revealed pathology in 16 of 19 patients, while 3 patients had normal findings. Ureteropelvic obstruction was found in 4 patients, obstructive megaureter in 8. Both ureteropelvic obstruction and obstructive megaureter were disclosed in 1 patient, partial ureteral duplication in 1 patient, and both complete ureteral duplication and ureterocele in 2 patients. In all patients, MIP and VR images could satisfactorily show the pathologies of the urinary tract. The estimated effective average doses of MSCTU were higher than IVU. Conclusion: Preliminary results of furosemide‐enhanced MSCTU demonstrated consistently dilated urinary tracts, obstruction levels, and underlying pathologies better than US and IVU.