Normal nasal cavity and paranasal sinuses in brown lemurs Eulemur fulvus: computed tomography and cross-sectional anatomy

Background Far less is known about the normal anatomy of the nasal cavity of Eulemur fulvus; no computed tomography (CT) scan has ever been published. Methods Relevant CT scans were taken in the transverse, dorsal and longitudinal planes. These scans were compared with anatomical sections of heads. Results Computed tomography scans revealed almost all nasal structures, but cannot differentiate between the various layers of the nasal mucosa. Results show a double‐scroll arrangement of the ventral nasal concha. The dorsal nasal concha protrudes into the maxillary sinus, but no protrusion into the frontal sinus was observed. The ethmoturbinate I is completely closed back on itself and rostrally voluminous. Conclusions This work shows that at a clinical level, the integrity of the different turbinates can easily be appreciated from a simple CT scan. It will assist clinicians to evaluate pathological conditions that affect the nasal region.     

Transposition of target information from the magnetic resonance and computed tomography scan images to conventional X-ray stereotactic space

A technique to apply reconstructed X-ray computed tomography (CT) and magnetic resonance imaging (MRI) for target determination in stereotactic Bragg peak proton beam therapy of intracranial lesions was developed. Twenty-one benign intracranial tumors and vascular abnormalities were managed using this technique. Clinical features of these lesions, as well as targeting problems associated with the MRI and CT image interpretation, are presented.     

Detection of bone erosions in rheumatoid arthritis wrist joints with magnetic resonance imaging, computed tomography and radiography

Background

The objectives of the present study were, with multidetector computed tomography (CT) as the reference method, to determine the performance of magnetic resonance imaging (MRI) and radiography for the detection of bone erosions in rheumatoid arthritis wrist bones, and to test whether measuring volumes of erosions on CT and MRI is reproducible and correlated to semiquantitative assessments (scores) of erosions on CT, MRI and radiography.

Methods

Seventeen patients with rheumatoid arthritis and four healthy control individuals underwent CT, MRI and radiography of one wrist, performed on the same day. CT was performed on a Philips Mx8000IDT unit (voxel size 0.4 mm × 0.4 mm × 1 mm) and MRI was performed on a Philips Panorama 0.6T unit (voxel size 0.4 mm × 0.4 mm × 0.4 mm). Images were evaluated separately for erosions in all wrist bones and were scored according to the principles of the Outcome Measures in Rheumatology Rheumatoid Arthritis MRI Scoring System (CT and MRI) and the Sharp/van der Heijde (radiographs) scoring methods. Measurements of erosion volumes of all erosions were performed twice with a 1-week interval.

Results

With CT as the reference method, the overall sensitivity, specificity and accuracy (concordance) of MRI for detecting erosions were 61%, 93% and 77%, respectively, while the respective values were 24%, 99% and 63% for radiography. The intramodality agreements when measuring erosion volumes were high for both CT and MRI (Spearman correlation coefficients 0.92 and 0.90 (both P < 0.01), respectively). Correlations between volumes and scores of individual erosions were 0.96 for CT and 0.99 for MRI, while they were 0.83 (CT) and 0.80 (MRI) for persons' total erosion volume and total score (all P < 0.01).

Conclusion

With CT as the reference method, MRI showed moderate sensitivity and good specificity and accuracy for detection of erosions in rheumatoid arthritis and healthy wrist bones, while radiography showed very low sensitivity. The tested volumetric method was highly reproducible and correlated to scores of erosions.     

Artifacts in magnetic resonance imaging and computed tomography caused by dental materials

Background

Artifacts caused by dental restorations, such as dental crowns, dental fillings and orthodontic appliances, are a common problem in MRI and CT scans of the head and neck. The aim of this in-vitro study was to identify and evaluate the artifacts produced by different dental restoration materials in CT and MRI images.

Methods

Test samples of 44 materials (Metal and Non-Metal) commonly used in dental restorations were fabricated and embedded with reference specimens in gelatin moulds. MRI imaging of 1.5T and CT scan were performed on the samples and evaluated in two dimensions. Artifact size and distortions were measured using a digital image analysis software.

Results

In MRI, 13 out of 44 materials produced artifacts, while in CT 41 out of 44 materials showed artifacts. Artifacts produced in both MRI and CT images were categorized according to the size of the artifact.

Significance

Metal based restoration materials had strong influence on CT and less artifacts in MRI images. Rare earth elements such as Ytterbium trifluoride found in composites caused artifacts in both MRI and CT. Recognizing these findings would help dental materials manufacturers and developers to produce materials which can cause less artifacts in MRI and CT images.     

Potentialities of temporal bone computed tomography in the identification of causes of hypoacusis of postinflammatory genesis

Temporal bone computed tomography (CT) was used to examine 64 patients with impaired hearing due to inflammatory diseases of the middle year. In 21 patients, the pathological process was bilateral. A total of 85 series of temporal bone CT scans were analyzed. The patients' age ranged from 2 to 66 years. CT verified adhesive otitis media in 62 cases, otosclerosis in 7, local malformation of the auditory ossicles and/or the labyrinthine fenestrae in 11. No CT changes were revealed in 5 cases. The CT symptoms of adhesive otitis media were identified. These included soft tissue bands and/or soft tissue-density portions that fix the auditory ossicles or block the niches of the labyrinthine fenestrae (31 temporal bones); sclerosis or ossification of the ligaments and tendons of the middle ear (7 temporal bones); calcification foci in the tympanic cavity (9 cases); osteosclerotic changes in the epitympanus (2 cases); cicatricial changes in the tympanic membrane (24 cases); destructive changes in the auditory ossicles (19 temporal bones). There has been evidence that CT may be used for the differential diagnosis of adhesive otitis media from otosclerosis and congenital malformations of the structures of the middle ear.     

Computed tomography and magnetic resonance imaging in the diagnosis of accessory nasal sinuses, upper jaw and nasal cavity tumors

Radiation studies, including computed tomography (CT) and magnetic resonance imaging (MRI), revealed that these techniques can accurately determine the site of a tumor, the borders of its spread to the adjacent anatomic structures. They also revealed the features of CT in detecting osseous structural destruction and the advantage of MRI in visualizing the soft tissue component of a neoplasm and in distinguishing the degree of contrast of tumor tissue and concurrent secondary inflammation. The accuracy of CT and MRI for small tumors is 45-80 and 29% higher than that of X-ray study and traditional tomography, respectively. The potentialities of all radiation diagnostic techniques for over 3.0-cm tumors are equal.     

Imaging of interstitial cryotherapy--an in vitro comparison of ultrasound, computed tomography, and magnetic resonance imaging.

RATIONALE AND OBJECTIVES: To evaluate the imaging capabilities of ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) in monitoring interstitial cryotherapy and to compare them with visual control. METHODS: An experimental MR-compatible, vacuum-insulated and liquid nitrogen-cooled cryoprobe was inserted under in vitro conditions into a porcine liver, which was kept at a temperature of 37 +/- 1 degrees C, in a water bath with continuous stirring. The freezing procedure was controlled macroscopically, by US (Toshiba Sonolayer, 7.5-MHz linear array transducer), by CT (Siemens Somatom Plus, slice thickness 2-8 mm, 165-210 mA at 120 kV), and by MRI (Philips Gyroscan ACS-NT, FFE TR/TE/FA = 15/5.4/25 degrees, T1-SE 550/20, T2-TSE 1800/100) after the iceball reached its maximum size. RESULTS: The maximum iceball diameter around the probe tip was 12.0 mm by visual control, 12.4 mm by US, 12.7 mm by CT, and within 12.8 mm by spin echo sequences and 11 mm by gradient echo sequence. Due to the nearly signal-free appearance of the frozen tissue on MR images, the ice/tissue contrast on T1-weighted and gradient echo images was superior to T2-weighted images and CT images. Sonographically, the ice formation appeared as a hyperechoic sickle with nearly complete acoustic shadowing. CONCLUSION: Due to the better ice/tissue contrast, T1-weighted or gradient echo MR images were superior to CT and US in monitoring interstitial cryotherapy. Gradient echo sequences generally underestimated the ice diameter by 15%.     

Proton magnetic resonance spectroscopy in patients with solitary and sporadic temporal lobe epileptic seizures

Proton magnetic resonance spectroscopy (¹H MRS) is an optional diagnostic method for potential epilepsy surgery candidates. The aim of this study was to determine the credibility of ¹H MRS examination in a group of patients suffering from solitary and sporadic epileptic seizures generated in temporal lobe. We recorded a 100% sensitivity of ¹H MRS in a group of ten patients in terms of detection of a pathological process in the temporal lobe. ¹H MRS also enabled determination of lateralization of the pathological process in three patients with bilateral epileptiform abnormalities on electroencephalography. Based on these results we suggest new perspectives on ¹H MRS as a part of standard diagnostic algorithm for solitary and sporadic temporal lobe epileptic seizures, particularly in cases with normal electroencephalography and magnetic resonance imaging findings.     

Diagnostic possibilities of contrast magnetic resonance tomography

The practice of examinations of more than 400 patients in the diagnostic center of CRIRR showed a high diagnostic efficiency of contrast MRA, especially in stenoses, occlusions, pathologic bends of the brachiocephalic vessels; aneurysms and stenoses of the abdominal and thoracic aorta, stenoses and occlusions of visceral branches of the abdominal aorta, iliac arteries including condition of vessels after surgical correction. Valuable facts have been obtained in vasorenal hypertension caused by stenoses, occlusions, extravasal compressions, additional arteries, and in the portal system (thrombosis of the main trunk and branches of the portal vein, signs of portal hypertension).     

Nasal cavities and paranasal sinuses in newborns and children]

The paranasal or accessory nasal sinuses begin their development as evaginations of the mucosa during the 3rd and 4th fetal months, but undergo their major expansion after birth according to the development of the facial cranium and the teeth. While in the newborn the sphenoidal and frontal sinuses are still only predispositioned, the ethmoidal labyrinth and particularly the maxillary sinus are of appreciable size. In the 4-year-old the frontal and sphenoidal sinuses are already developed and in the 12-year-old the paranasal sinuses reach their final form and a size equivalent to the adult.     

Magnetic resonance tomography, computed tomography and ultrasonic diagnosis of hemangiomas of the liver

The paper is concerned with the potentialities of modern radiation methods in the diagnosis of liver hemangiomas. USI, CT, angiography and MR-tomography (MRT) were used for investigation of 64 patients with liver hemangiomas. The diagnostic potentialities and the role of each of the above methods in the diagnostic algorithm in liver hemangiomas were studied. The results of the investigation have shown that MRT possesses a higher informative value than USI and CT in the diagnosis of liver hemangiomas and can even replace angiography in the verification of diagnosis.     

Preoperative computed tomography of temporal bones and its use in selecting patients with sensorineural deafness for cochlear implantation

Cochlear implantation (CI) involves the insertion of electrode systems in the inner ear in order to restore hearing in patients with sensorineural deafness. Positive CI results are closely related with careful selection of candidates. Preoperative computed tomography (CT) and its results are decisive in this selection. Temporal bone CT was made in 40 patients aged 1 to 57 years who had sensorineural deafness. The following changes were detected: malformations of the inner ear, the inner auditory canal, meningititis-induced cochlear obliteration, post-traumatic temporal bone changes, local auditory ossicle malformation, inflammatory middle ear changes, the high position of the jugular vein bulb, and its diverticula. Temporal bone CT plays an important role in selecting candidates for CI and circumvents potential difficulties and complications at CI.     

Data distributions in magnetic resonance images: A review

Many image processing methods applied to magnetic resonance (MR) images directly or indirectly rely on prior knowledge of the statistical data distribution that characterizes the MR data. Also, data distributions are key in many parameter estimation problems and strongly relate to the accuracy and precision with which parameters can be estimated. This review paper provides an overview of the various distributions that occur when dealing with MR data, considering both single-coil and multiple-coil acquisition systems. The paper also summarizes how knowledge of the MR data distributions can be used to construct optimal parameter estimators and answers the question as to what precision may be achieved ultimately from a particular MR image.