Computed tomography and magnetic resonance imaging of hydatid disease: A pictorial review of uncommon imaging presentations.

Hydatid disease (HD), also known as echinococcal disease or echinococcosis, is a worldwide zoonosis with a wide geographic distribution. It can be found in almost all parts of the body and usually remains silent for a long period of time. Clinical history can be varied based on the location, size, host immune response, and complications. The most common imaging modalities used for diagnosis and further evaluations of HD are ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI). Although conventional radiography may be the first used tool, rarely can lead to a definite judgment. Clinical indications and cyst location may alter the choice of imaging. MRI and CT would be useful when the involved area is inaccessible for ultrasound or surgical treatment is required. CT is particularly valuable for osseous organ involvements and the presence of calcifications in the cyst and also demonstrates the size, number, and local complications. MRI can differentiate HD from neoplasms in cases with an unusual appearance on imaging. Moreover, it is preferable in biliary or neural involvements. Besides, more detailed images of MRI and CT could help to resolve the diagnostic uncertainty. Imaging is the main stem for HD diagnosis. Brain, orbit, muscle, bone, and vascular structures are less commonly involved areas. Familiarity with typical clinical presentation, CT scan and MR imaging findings of HD in this sites facilitate the radiologic diagnosis and guiding appropriate treatment.

Factors affecting dural sinus density in non-contrast computed tomography of brain.

The possibility of changing the intracranial vasculature computed tomography (CT) attenuation under the influence of variable factors is a long-held unestablished belief. The purpose of this study is to evaluate factors affecting dural sinus density in non-contrast computed tomography of the brain. Patients presented with acute neurologic symptoms to the emergency department were candidates to be enrolled in this study. A region of interest (ROI) measuring 1-2-mm2 recorder (base on sinus size) used to measure the attenuation of each sinus in Hounsfield Unit (HU) and then mean density calculated. CBC, BUN and Cr were extracted from patients' records. Chi-square test, correlation analyze, independent sample unpaired student t-test and one-way ANOVA test and Multivariate logistic regression were used. Positive significant correlation (0.48) was found between the hematocrit level (HCT) and average attenuation in the four sinus segments (P value < 0.0001) and between the HCT and basilar artery attenuation (P value < 0.0001). There was no significant correlation between the age and average attenuation. There was a significant and negative correlation between the BUN/Cr and average attenuation. Using a multivariate analysis on a large sample volume, we conclude that Hgb and HCT are the only factors that have a significant correlation with average sinus attenuation. This correlation is relatively stronger for Hgb in comparison to HCT.

Improvement of distension and mural visualization of bowel loops using neutral oral contrasts in abdominal computed tomography.

AIM: To assess and compare the image quality of 4% sorbitol and diluted iodine 2% (positive oral contrast agent) in abdomino-pelvic multi-detector computed tomography. METHODS: Two-hundred patients, referred to the Radiology Department of a central educational hospital for multi-detector row abdominal-pelvic computed tomography, were randomly divided into two groups: the first group received 1500 mL of 4% sorbitol solution as a neutral contrast agent, while in the second group 1500 mL of meglumin solution as a positive contrast agent was administered in a one-way randomized prospective study. The results were independently reviewed by two radiologists. Luminal distension and mural thickness and mucosal enhancement were compared between the two groups. Statistical analysis of the results was performed by Statistical Package for the Social Sciences software version 16 and the Mann-Whitney test at a confidence level of 95%. RESULTS: Use of neutral oral contrast agent significantly improved visualization of the small bowel wall thickness and mural appearance in comparison with administration of positive contrast agent (P < 0.01). In patients who received sorbitol, the small bowel showed better distention compared with those who received iodine solution as a positive contrast agent (P < 0.05). CONCLUSION: The results of the study demonstrated that oral administration of sorbitol solution allows better luminal distention and visualization of mural features than iodine solution as a positive contrast agent.

Temporal Bone Measurements; A Comparison Between Rendered Spiral CT and Surgery.

BACKGROUND: Accurate radiological assessment of the anatomical features of the temporal bone is crucial to prevent damage to vital elements in this area during surgery. Knowing the approximate location of specific temporal bone related landmarks in advance is very important for planning surgery. OBJECTIVES: This study compared findings from computed tomography images with those observed directly during ear surgery. PATIENTS AND METHODS: Patients with various pathologies of the ear who needed surgery were referred to an imaging center for a spiral CT scan of the temporal bone. The following parameters were measured by a radiologist and also later recorded by the surgeon during surgery: 1) The distance between the postero-superior border of the outer ear canal and the sigmoid sinus; 2) The distance between the dome of the lateral semicircular canal and the mastoid cortex; and 3) The distance between the external surface of the incus and the mastoid cortex. RESULTS: Twenty cases were included. In the three measurements performed in this study, only the first parameter (distance between the canal and the sigmoid sinus) was significantly different between the direct measurement made during surgery and that obtained from CT scans. There was no significant difference in the measurements of the distance between the dome of the lateral semicircular canal and the bone cortex, and the distance between the external surface of the incus and the surface of the bone cortex. CONCLUSIONS: Our study shows in terms of figures that measurements of features of the temporal bone made from spiral CT scan images and those directly obtained during surgery are similar to an adequate extent.

Radiological features of osteoid osteoma: pictorial review.

Osteoid osteoma is a benign bone tumor of undetermined etiology, composed of a central zone named nidus which is an atypical bone completely enclosed within a wellvascularized stroma and a peripheral sclerotic reaction zone. There are three types of radiographic features: cortical, medullary and subperiosteal. Forty-four patients with osteoid osteoma were studied retrospectively. In plain films, 35 patients presented as the cortical type, six cases were located in the medullary zone and three had subperiosteal osteoid osteoma. In all the cases, the nidus was visualized on computed tomography (CT) scan. The nidus was visible in four out of five patients who had also undergone magnetic resonance imaging (MRI). Double-density sign, seen on radionuclide bone scans was positive in all patients. MRI is more sensitive in the diagnosis of bone marrow and soft tissue abnormalities adjacent to the lesion, and in the nidus that is located closer to the medullary zone. On the other hand, CT is more specific when it comes to detecting the lesion's nidus.