Search

High resolution CT (HR-CT) scanning of the temporal bone was performed in three patients with a fully expressed mandibulofacial dysostosis for preoperative assessment of temporal bone abnormalities. The external auditory canal was absent in five of six ears. Scans revealed a dysplastic middle ear cleft with dysplastic and partly dislocated ossicles. The ossicles were absent in two temporal bones. In no patient was the mastoid bone pneumatised. The inner ear was affected in only one patient in whom a shortening of the lateral semicircular canal could be found bilaterally. The role of HR-CT of the temporal bone as a preoperative diagnostic tool for the assessment of abnormalities of surgical import is discussed.

High-resolution CT of the petrous bone was carried out in 259 patients with clinically diagnosed abnormalities of the inner ear; in some the lesions were bilateral. In 62 patients (approximately 20%), the scans showed findings which related to the signs and symptoms. Patients with hearing loss and vestibular neuronitis showed no abnormalities. Amongst the remaining patients, the most common findings were acoustic neuromas (17 cases), cochlear otospongiosis (14 cases), malformations (13 cases) and tumours or cholesteatomas of the labyrinth (13 cases) as well as single rare isolated lesions.

The CT and conventional radiological findings in 30 patients with space-occupying lesions of the pelvic bones were compared. 73% of the tumours diagnosed by CT were shown by conventional means and in 71% their extent was correctly estimated. Lesions at the ilio-sacral junction are not demonstrated as well by conventional methods as those near the hip joint. The lesions most frequently missed by conventional radiography lie in the dorsal part of the ilium and in the lateral mass of the sacrum.

Eleven patients with known malignant tumours of the outer ear and three patients with otitis externa maligna were examined by high resolution CT. CT provided accurate information concerning soft tissue infiltration into the parotid or subtemporal tissues, and of the bony destruction in the mastoid, meatus and tympanic cavity. Absolute differentiation between a malignant tumour and otitis cisterna maligna is not possible, not even by high resolution CT.

Beside demonstrating morphological changes, CT enables one to make quantitative measurements of the spinal canal (sagittal diameter, transverse diameter, area of the spinal canal, width of the lateral recess and symmetry of the articular joints). A reduction of the transverse diameter of the spinal canal or asymmetry of the articular joints is associated with an increased and earlier incidence of back pain. In addition, patients with asymmetrical vertebral joints showed more frequent and earlier development of disc prolapse.

The diagnostic scope of CT has been demonstrated for malignant tumours of the oesophagus (41 patients) and tumours of the stomach (18 patients). Of importance is the demonstration of circumferential spread of tumours of the oesophagus, the early demonstration of mediastinal lymph node metastases and the demonstration of infradiaphragmatic lymph node involvement from tumours of the middle and lower thirds of the oesophagus. In the presence of tumours of the stomach, it is possible to demonstrate infiltration of neighbouring organs (pancreas, spleen, hilum of liver) and haematogenous or lymphatic spread.

Contrast injection for angio-CT shows kinetic changes in patients with portal hypertension due to cirrhosis of the liver when compared with normals. Contrast-duration diagrams show a higher aortic peak, low contrast and delayed contrast maximum in the liver and portal vein in patients with liver cirrhosis and portal hypertension. On these criteria it is possible to distinguish patients with cirrhosis (n = 18) from normals (n = 16).

Twenty-one patients with congenital deformities of the petrous bones were examined by high resolution computed tomography. This allows an accurate description of the extent of the malformation in all parts of the cochlear and vestibular organs; only localised changes in the auditory ossicles, such as fixation of the stapes and changes in the soft tissue portions of the labyrinth, cannot be shown. Improved demonstration of soft tissues while using less radiation makes high resolution CT preferable to conventional polytomography. It is also easier to perform and provides axial projections which are essential for the elucidation of malformations of the middle and inner ear.

The CT findings in 80 patients with confirmed portal hypertension due to intrahepatic block were analysed retrospectively. The findings included ascites, hypo-dense areas in the liver, nodular or irregular liver contour, the inability to define intrahepatic portal vessels with narrow window settings, the so-called "kissing" sign and evidence of hepato-fugal collaterals and thickening of the wall of the oesophagus. Electronic measurements of various organs (liver, spleen) and vessel diameters (portal vein, superior mesenteric vein) provide parameters which permit classification of patients into the cirrhotic group, as compared with a control group. The statistical significance of this classification was checked by the Kolmogoroff-Smirnoff test.

The diagnostic value of sonography and CT was studied in 259 patients. In the diagnosis of solid tumours, CT is superior to sonography, whereas ultrasound is more useful in the investigation of cystic lesions. In estimating the extent of intrahepatic tumours, the falciform ligament is more useful than a line from the cava to the gall bladder, both for CT and ultrasound, although in this case CT shows the extent of tumours more accurately. 3.7% of the ultrasound and 2.3% of the CT examinations were of limited value because of unavoidable technical problems.

The findings of conventional radiography were compared with the results of computer tomography in 91 patients with histologically confirmed lesions of the thoracic wall. In 22 (24%) CT gave no additional information. In 67 (74%), CT supplied additional information or narrowed the differential diagnosis. Particularly important on computer tomography was the enhancement brought about by intravenous contrast medium in malignant tumours of the thorax or thoracic wall. CT should be used in preference to conventional tomography in the investigation of lesions of the thoracic wall.

The computer tomographic appearances of very rare sarcomas of the liver have been demonstrated in five cases (four haemangiosarcomas, one spindle-cell sarcoma). On the plain scan, all the tumours appeared less dense than the liver parenchyma, but in haemangiosarcomas there was a marked increase in density after the infection of contrast up to an isodense level. During angio-CT, densities equal to intrahepatic vessels were observed. There was only a slight increase in density of the spindle cell sarcoma after contrast injection. The CT appearances have been compared with the pathological and anatomical structure of the tumour.

High resolution computer tomographic examinations of the petrous bones were performed on 19 patients with confirmed peripheral facial nerve paralysis. High resolution CT provides accurate information regarding the extent, and usually regarding the type, of pathological process; this can be accurately localised with a view to possible surgical treatment. The examination also differentiates this from idiopathic paresis, which showed no radiological changes. Destruction of the petrous bone, without facial nerve symptoms, makes early suitable treatment mandatory.

Computed tomography of the heart represents an expansion of the non invasive roentgenological diagnosis of cardiac lesions 1. by the representation of the heart in a horizontal sectional image, free from overlapping effects, with the resulting additional anatomical information; 2. by the visualization of all chambers of the heart in a single examination; 3. by the direct demonstration of the ventricular septum and ventricular myocardium; 4. using ECG-gated cardio-CT, by the non invasive assessment of ventricular wall motion; 5. by the non invasive demonstration of coronary bypass perfusion.

A method for calibrating the radius of rotating, harmonic sensing coils is proposed that allows relaxing constraints on alignment and field errors of the reference quadrupole magnet. Radius calibration considering roll angle misalignment between the measurement bench, the magnet, and the motor-drive unit is studied first. We then study the calibration error when a harmonic field error of higher order is present in the calibration magnet. This also yields a calibration whena sextupole magnet is used, for example, when an insitu calibration is required. The proposed calibration method has been validated by simulations with the