Biomedical subjects
Publications and source records attributed to R R Mawhinney.
We conclude that the CT scout film is a more accurate and reproducible method for FAA measurement. The cost difference is minimal and might be expected to lessen as overheads are reduced for the CT scanner.
Forty-one patients with 45 pelvic mass lesions were assessed by magnetic resonance imaging (MRI). All lesions were initially considered to be benign ovarian masses with this diagnosis confirmed in 36 lesions. The characteristics on MRI are analysed and features useful in predicting histological type identified. Our results indicate that a high, though not absolute, level of diagnostic specificity should be obtainable in identification of ovarian pathology.
A prospective randomised trial was performed to examine the value of ureteric compression in intravenous urography. Calyceal distension improved during the urogram in 68% of kidneys when compression was used, in contrast to an improvement of 43% in patients not receiving compression. In both heavy patients and those with a large girth a trend towards improved distension was shown but was significant only in the former group.
Thirty-two patients suspected by Computed Tomography (CT) of having a meningioma were additionally imaged by Magnetic Resonance. Of these, seven patients had an eventual diagnosis other than meningioma. This represents a positive value of 76% for the diagnosis of meningioma by CT. Magnetic resonance imaging (MRI) improved positive predictive value to 86%. A diagnosis other than meningioma was made by MRI with greatest confidence when tumour signal intensity was either much greater or much less than that of grey matter. Comparison of Inversion Recovery (IR) and spin echo (SE) sequences showed IR to be superior for demonstration of supratentorial meningiomas. SE images were superior to IR in demonstrating calcification. MRI was of value in showing anatomical relationships, due to its multiplanar capacity and in demonstrating vessel patency. CT was generally superior in defining meningiomas and in demonstrating calcification.
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A variety of extra-axial lesions occurring at the cerebello-pontine angle was examined by magnetic resonance imaging (MRI). Differences in spin sequence characteristics were found between neurilemmomas and meningiomas, with neurilemmomas exhibiting a greater increase in T2 than meningiomas. The T1 images were of less value in differentiating between neurilemmomas and meningiomas but were of value in the diagnosis of vascular lesions, due to the decreased T1 of blood clot. The T1 images were also of value in the assessment of tumour size and in the diagnosis of an epidermoid cyst. Extension of tumour into the internal auditory meatus was seen on MRI with acoustic neuromas and with one other lesion. The transverse perspective was of greatest value in lesion assessment. The coronal perspective was useful in certain situations but the sagittal perspective was of minimal clinical value.
Forty-nine patients with a space occupying lesion in the cerebellopontine angle cistern were examined by computed tomography (CT), magnetic imaging (MRI) and, where appropriate, conventional neuroradiologic techniques. The presence of an intracanalicular extension and a high signal on T2 weighted sequences were typical of acoustic neuroma and allowed separation from meningioma. Contrast enhancement with gadolinium DTPA was particularly valuable in recurrent acoustic neuroma. Typically epidermoids had long T1 and T2 values. Sequences which highlight flow allow vascular lesions to be identified without the use of contrast media. In separating the several pathologies MRI was superior to CT and also gave information on tissue composition in acoustic neuroma.
A study was made of 15 patients with rheumatoid involvement of the neck in whom neurologic symptoms were of sufficient severity that operative intervention was being planned. Magnetic resonance imaging (MRI) was performed in all patients and compared with conventional radiography, conventional tomography, myelography and computed tomography (CT) assisted myelography. MRI clearly demonstrated any deformity or compression of the cord and was able to show the effects of flexion and extension of the neck. It is concluded that MRI could replace myelography for defining cord compression. If details of atlanto-axial alignment and bony outline of the spinal canal are required then CT will provide the appropriate images.