Computerized radiology : official journal of the Computerized Tomography Society最新文献

A case of pulmonary endometriosis in a woman with catamenial hemoptysis is reported. This diagnosis was established by cessation of the hemoptysis following hormonal treatment. Computed tomography appears to be the method of choice for a correct intrapulmonary localization of this disease.

CT has demonstrated its usefulness in the evaluation of the known solitary pulmonic nodule, however its application to the solitary nonpulmonic nodule has not been emphasized. Three cases illustrate the applicability of CT in localization of a nodule. The importance of obtaining bone windows in these cases is stressed. When comparison plain films and routine techniques are unsatisfactory, CT is valuable in providing a noninvasive means of diagnosis and patient reassurance.

Renal angiomyolipomas are rare benign tumors readily identified by computed tomography due to their high fat content. When they attain giant proportions other fatty neoplasms, specifically liposarcomas, cannot be excluded based on the radiographic findings. A case in which a notch defect in the lateral border of the kidney was the single most important clue as to the intrarenal origin of the mass and led to the correct pre-operative diagnosis is presented.

Records of 902 patients with possible abdominal abscess were reviewed and of these 198 had abscesses on at least one occasion imaged either with ultrasound (US) or computed tomography (CT). There were 235 episodes of either one or simultaneous multiple abscesses. Sensitivities of CT and US were analyzed according to anatomic site. The nature of errors made was tabulated. CT was significantly more sensitive than US for the detection of abdominal abscess. Causes of CT and US error in abscess detection are discussed, and recommendations regarding choice of exam and means of improving performance are made.

The diagnosis of herniation of the left ventricle through a pericardial window was made using MRI. This is a rare type of herniation because it presented 6 years after a pericardial window was made for pericarditis. Herniation of the heart through congenital, traumatic and post surgical pericardial defects are discussed.

Denervated muscles due to lumbar radiculopathy, peroneal axonal neuropathy and hypoglossal neuropathy were studied with magnetic resonance imaging (MRI). Denervated muscle was clearly distinguished from normal muscle by its higher intensity signal. Comparison of the resulting signal intensity of the muscle using various imaging parameters suggests an alteration in water macromolecular binding. These preliminary findings indicate that MRI may be useful in the noninvasive in vivo diagnosis and study of the effects of denervation on muscle.

Twenty-six cases of porencephalic cysts were analyzed. The cysts were multiple in 26.9% and were associated with subarachnoid cysts in 11.5%. The main presentations were seizures, cerebral palsy and mental retardation. The unifocal cysts were mainly in the frontoparietal region, suggesting a congenital aetiology. Multiple cysts were noted in the basal ganglia region. A case of multiloculated cysts, of unknown aetiology, is noted. The aetiology of multifocal porencephaly and a diagnostic method of differentiating congenital from acquired porencephaly are discussed.

A case of malignant fibrous histiocytoma of the lung is reported in pediatric patient-uncommon location as well as age group.

The cylindrical design of most head coils utilized with current magnetic resonance (MR) imaging units and the necessity of close approximation of the coil to the head to maximize signal-to-noise ratio precludes flexion or extension of the head to any significant degree during imaging of the brain. For this reason, the canthomeatal line is approximately parallel to the standard transverse magnetic axis. Standard computed tomography (CT) scans in the transverse plane are usually obtained at an approximately 25° angle to Reid's baseline (RBL). This leads to projection differences in viewing and comparing standard transverse MR and CT studies. High convexity lesions which may present anteriorly on a given CT section may present posteriorly on an MR section which appears to be at a comparable level on first inspection. Secondly, one or more transverse MR sections usually display a portion of the occipital lobes behind the cerebellar hemispheres. The region of the tentorium and straight sinus can occasionally give rise to a vermiform appearance (the “AVM artifact”). Thirty patients were studied with MR at a 20–30° angulation to RBL without any loss of image quality and with excellent visualization of the posterior fossa. The effect of transverse axis change on lesion position was demonstrated in five high convexity lesions and by utilizing fixed brain specimens. While clearly MR can accurately localize lesions utilizing orthogonal multiplanar techniques, it is suggested that investigators and clinicians currently performing MR studies of the brain consider potential advantages of electronic angulation techniques for comparative clinical studies and certain research applications.

The display of computerized tomographic (CT) data requires data compression because of the limited shades of grey which the eye can differentiate. This may lead to information loss which can be minimized by a more efficient utilization of the available levels of grey than that afforded by conventional linear windows. Automated histogram equalization for grey level assignment has not been satisfactory because of the underlying assumption that the information content at any given CT level is proportional to the number of pixels at that level. For four different anatomic regions; the lumber spine, abdomen, brain and chest, an empiric graph of the clinical information content vs CT levels was integrated to yield the shape of a graph assigning shades of grey vs CT level i.e. a non-linear window. This non-linear window curve was utilized in the same manner as the linear window, namely the window center and width were under the direct control of the observer through the window center and width knobs. Each non-linear window was implemented on images of its anatomic region and interactively optimized on the screen till a maximal display of information was obtained. These optimal non-linear windows compared favorably with linear windows in most cases. This method provides the means to display more information on a CT image with no extra processing time, additional equipment or special training.