Imaging techniques.
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Biomedical subjects
Publications and source records attributed to G R Cherryman.
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White matter lesions and T1 changes were identified using NMR and then compared between groups of patients suffering from dementia of the Alzheimer type (DAT), Multiple infarct dementia (MID) and normal controls. All DAT and MID patients were also imaged with a gamma camera using 123Iodo-n-isopropyl-amphetamine, a radiopharmaceutical whose uptake in the brain follows the regional blood flow. While NMR was not able to differentiate between DAT and MID, 19 out of 21 DAT patients compared to four out of 18 MID patients showed bilateral parietal lesions on IMP scans.
Patients with chronic schizophrenia were examined by nuclear magnetic resonance imaging of the brain. Subgroups of the syndrome with high positive or high negative symptom scores and ventricular dilatation were compared with each other and with normal controls in respect of regional spin lattice relaxation time (T1) changes. Significant differences were not observed between the schizophrenic subgroups and controls but there were significant differences between the subgroups themselves. The presence of tardive dyskinesia was associated with increased T1 of the basal ganglia. The significance of these results is discussed in relation to findings using other techniques.
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To compare the specificity of T1 measurement for the diagnosis of prostatic carcinoma in vivo, two groups of patients with clinically enlarged prostate glands have been imaged. One group comprising 25 patients was imaged at 1.7 MHz the other comprising 51 patients at 3.4 MHz. T1 measurements together with the gross anatomical appearances of the prostate gland were observed and compared with the clinical and histologic diagnoses. At 1.7 MHz it was found that the T1 measurement of carcinoma of the prostate and benign hypertrophy of the prostate fell into two distinct ranges with no overlap between the two conditions. Three false-positive diagnoses of carcinoma were made in patients with prostatitis where the T1 values fell in the upper part of the carcinoma range. T1 measurement in the group studied at 3.4 MHz demonstrated no specific value for either condition and diagnosis of malignancy had to be made from the morphologic appearances of the gland. Morphologically benign hypertrophy appeared homogeneous while carcinoma appeared heterogeneous with small areas of increased T1 in the malignant part of the gland.
In addition to being a non-ionising method of imaging, nuclear magnetic resonance has the ability to demonstrate the body organ using different radio pulse sequences in order to highlight different tissues. Neuroblastomas are best demonstrated using proton spin lattice relaxation time (T1) weighted images such as inversion recovery or calculated T1, rather than proton density. The ability to produce sections in the sagittal and coronal as well as the axial plane allows for accurate tumour localisation and management planning. The appearances of primary neuroblastoma and metastatic spread to bone are described in three cases of neuroblastoma.
The nuclear magnetic resonance images obtained in a case of adrenoleukodystrophy are presented. The areas of demyelination are clearly seen. The T1 values of the affected areas are not specific and coincide with those previously recorded in the lesions of multiple sclerosis or cerebrovascular disease. A diagnosis of adrenoleukodystrophy should be considered in younger male patients presenting with behavioural disturbances, especially when these are associated with abnormalities of vision or gait. There may be no clinical evidence of the associated adrenocortical insufficiency.
The significantly different signals from the various structures within the orbit suggest that NMR tomography will prove to be a valuable method for the diagnosis of both ocular and orbital disease. The resolution of the technique is initially illustrated by the demonstration of the signal patterns from the normal globe and orbit. The characteristic features of some pathological conditions, including vitreous haemorrhage and retinal detachment, are then shown. The value and limitations of the technique in differentiating conditions such as choroidal haemorrhage from malignant melanoma, and intra-orbital lymphoma from pseudo-tumour, are illustrated and discussed. The absence of artefact from bone, synthetic lens implants and non-ferromagnetic metallic foreign bodies is stressed.
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The thoracic spines of a group of 48 oncology patients were examined with high field (1.5 T) magnetic resonance (MR) imaging. Sagittal T1-weighted sections were obtained in all patients. Even using this single sequence an unexpectedly high prevalence of thoracic disk herniation (14.5%) was demonstrated. Thoracic disk herniation shown by MR may not be related to the patients' symptoms.
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Forty-four patients with small cell carcinoma of the bronchus underwent CT and MR studies of the brain to detect cerebral metastases. All patients were studied with contrast-enhanced CT scans, short (T1-weighted) and long (T2-weighted), spin-echo (SE) and FLASH 90 degrees MR sequences. Gd-DTPA enhanced SE-T1 and FLASH 90 degrees sequences were also obtained. A quantitative comparison of the results was carried out to assess the sensitivity of the different techniques in the detection of brain metastases according to lesion diameter. Metastases were identified in 19/44 patients (43%). All techniques detected the lesions greater than 2 cm; of the metastases less than 2 cm, 63/124 (51%) were detected only by Gd-DTPA SE-T1 and FLASH sequences and 11 more (9%) only by Gd-DTPA SE-T1 scans. All the lesions identified on enhanced CT scans or on T2-weighted images were easily detected by Gd-DTPA scans. CT sensitivity was higher than that of pre-contrast SE-T1 and FLASH studies and only slightly lower than that of T2-weighted images. As for lesions less than 2 cm, Gd-DTPA T1-weighted sequences had the highest detection rate (124 lesions) versus Gd-DTPA FLASH 90 degrees scans (113 lesions) and precontrast T1-weighted scans (45 lesions). When comparing Gd-DTPA SE-T1 and FLASH 90 degrees sequences in the detection of lesions less than 1 cm, we observed that the latter missed 9% of metastases, mainly due to a high rate of magnetic susceptibility artifacts and to lower contrast resolution. Therefore, Gd-DTPA SE-T1 images still remain the most accurate technique in the assessment of cerebral metastases.
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