Proton magnetic resonance spectroscopy of basal ganglia in chronic fatigue syndrome.

Fatigue is a common symptom of neurological diseases that affect basal ganglia function. We used proton magnetic resonance spectroscopy ((1)H MRS) to study the metabolic functions of the basal ganglia in chronic fatigue syndrome (CFS) to test the hypothesis that fatigue in CFS may have a neurogenic component. (1)H MRS of left basal ganglia was carried out in eight non-psychiatric patients with CFS and their results were compared to age- and sex-matched healthy asymptomatic healthy controls. A highly significant increase in the spectra from choline-containing compounds was seen in the CFS patient group (p < 0.001). In the absence of regional structural or inflammatory pathology, increased choline resonance in CFS may be an indicator of higher cell membrane turnover due to gliosis or altered intramembrane signalling.

Solid localization marker for MR imaging.

A solid, stable material that can be easily cut into unique, identifiable shapes was compared with other localization markers used in magnetic resonance imaging to determine relaxation characteristics and chemical shift. The solid marker and the conventional oil-based markers caused substantial chemical shift artifacts and so should never be used when high levels of spatial accuracy are necessary, such as in stereotaxy. Although it had the lowest T2 of all the substances tested, the solid marker was useful in identifying structures when different coils, sequences, and fields of view were used.

Acute subdural haematoma in the conscious patient: outcome with initial non-operative management.

We have retrospectively reviewed 23 conscious patients, in whom a CT scan diagnosis of acute subdural haematoma was made, and in whom craniotomy for evacuation was not initially performed. These highly selected patients represent 3% of 837 patients with acute subdural haematoma, presenting over a five year, eight month period to the Institute of Neurological Sciences, in Glasgow (1986-1991). Patients with any other associated intracranial abnormalities, such as cerebral contusions, as shown on CT, were excluded from this report. All patients were followed by serial CT scanning, and neurological assessments. Cerebral atrophy was present in over half of the sample. In 17 of our patients, the acute subdural haematoma resolved spontaneously, without evidence of damage to the underlying brain, as shown by CT or neurological findings. Six subsequently required burr hole drainage of a hypodense liquid subdural haematoma. In each of these patients, haematoma thickness was greater than 10 mm. Haematoma volume was significantly larger (53 +/- 6 ml versus 32 +/- 2 ml) in the group who came to operation. The mean delay between injury and operation in this group was 15 days. We conclude that certain conscious patients with small acute subdural haematomas, without mass effect on CT, may be safely managed conservatively.

Multi-modality image combination: five techniques for simultaneous MR-SPECT display.

Increasingly, images are being acquired of the same patient using two or more diagnostic imaging modalities. If one such modality is MRI then a data set showing essentially anatomical information is produced. If the second is SPECT using HMPAO then a data set showing cerebral perfusion is also produced. The ability to conjoin such anatomical and functional data is an important goal in radiology. In this technical report five display strategies are investigated as a means of conveying simultaneously to the radiologist all the information from two such data sets. Illustrative examples are given for each display technique. Preliminary observations are made regarding comprehensibility, information loss and efficiency in conveying all the information simultaneously, for all five techniques.

The use of in vitro magnetic resonance tissue studies to optimise pulse sequences in the imaging of intracranial haemorrhage.

The choice of appropriate MR pulse sequences to highlight a particular pathology to best advantage is not always straightforward. In this study of intracranial haemorrhage, tissue relaxation times measured in vitro were entered into a computer program which calculated the signal intensity of each tissue (brain, blood, CSF, and bloody CSF) for all possible echo (TE) and repeat (TR) times. Analysis of graph plots of the results enabled the selection of pulse sequences which gave optimal separation of the signal intensities of intracranial haemorrhage from those of normal intracranial contents. The sequences thus chosen were used successfully in the imaging of patients with intracranial haemorrhage.

Quantification of cord deformation and dynamics during flexion and extension of the cervical spine using MR imaging.

The magnetic resonance (MR) cine display of flexion and extension (F/E) manoeuvres in the cervical spine has proved useful in the evaluation of cord compression due to bone and joint instability, spondylosis, and multiple tumours. It has advantages over X-ray F/E and CT myelography in that it is noninvasive and produces images with high soft tissue contrast. The MR F/E technique does have its limitations, however, in that each structure in the images has a degree of independent movement and rotation that can make visual interpretation difficult. It also does not address the problem of assessing the relative significance of each lesion where numerous lesions may be present, for example, in compression due to spondylosis, rheumatoid arthritis, or neurofibromatosis. In this paper a novel technique is described that produces quantitative indices of cord deformation and dynamics during MR F/E. A computer program automatically calculates a series of contiguous profiles perpendicular to the cord throughout its length and for each image in the manoeuvre. Orthogonal polynomial curve fitting techniques are used to fit these profiles and extract statistical parameters that are quantitative indices of deformation and dynamics. The four main parameters calculated are kurtosis as an index of bilateral cord compression, skewness as an index of unilateral or asymmetric contact pressure, angulation as a measure of cord deformation about a lesion, and anteroposterior cord width as a direct measure of indentation and attenuation. Illustrative examples of results from normal volunteers and patients suffering from cervical myelopathy are presented. The technique may prove particularly useful to the spinal surgeon in assessing the relative significance of individual lesions and may also be a powerful research tool in the study of cord biomechanics in the living body.

Strontium-89 therapy: strontium kinetics and dosimetry in two patients treated for metastasising osteosarcoma.

We report a study of strontium kinetics in two patients who received 89Sr therapy for disseminated osteogenic sarcoma, together with estimates of absorbed dose to the principal metastases and to bone marrow. In neither patient did tumour uptake of strontium have a significant effect on whole-body retention. In one patient, whole-body strontium kinetics agreed closely with the ICRP standard model, while in the second, retention was extremely prolonged, probably due to hypertrophic osteoarthropathy. Strontium-85 scintigraphy, surface counting and high-resolution whole-body profiles agreed in showing that in both patients tumour turnover of strontium was very rapid, with a biological half-life of only a few days. Absorbed dose to tumour was found to be comparable in magnitude to the mean bone-marrow dose. We have no reason to believe that 89Sr therapy was of clinical benefit to either patient.

Accuracy of stereotaxic localisation using MRI and CT.

The accuracy of stereotaxic coordinates determined using the Leksell apparatus with CT and MRI was investigated using an Agar filled head phantom. Both imaging techniques were found to produce an accuracy of better than 2 mm with the exception of the Z coordinate as measured by CT (2.3 mm). This latter error is greater because of the 3 mm slice width used. Direct coronal views were used to determine Z more accurately using MRI. The measurement procedures are described and it is shown that the Leksell system of using orthogonal coordinates enables the scaling of images, which is particularly necessary with MRI, to be done easily.

A quantitative index of ventricular and extraventricular intracranial CSF volumes using MR imaging.

A new technique is described that utilises a novel magnetic resonance pulse sequence to produce a quantitative index both for ventricular and, for the first time, extraventricular intracranial CSF volumes. The pulse sequence is a combination of a null-point inversion recovery sequence with an extended spin-echo read (echo time = 400 ms), which produces a contrast of CSF to white or grey matter of approximately 120:1. A series of experiments are performed on phantoms representing CSF filled ventricles and sulci over a wide range of volume values, and it is found that the standard deviation of differences between true and estimated values is 3.9% for ventricles, 4.6% for total cranial CSF, and 7.9% for CSF within the sulci. Normal volunteer reproducibility studies revealed corresponding standard deviations of less than 5.5%. Using the technique to produce absolute estimates of CSF volumes in normal subjects and patients produced results in good agreement with previously published necropsy studies. The technique has wide neurological and neurosurgical applicability particularly in terms of differential diagnosis and as an objective monitor of therapy or progression in conditions such as hydrocephalus, atrophy, and benign intracranial hypertension.

Potential of SeHCAT retention as an indicator of terminal ileal involvement in inflammatory bowel disease.

The absorption of 75Se-23-selena-25-homotaurocholate (SeHCAT) was compared with vitamin-B12 absorption and conventional radiography in 44 patients with inflammatory bowel disease. The retention of SeHCAT was normal in 11 patients with ulcerative colitis but was abnormally low in 9 patients with terminal-ileal resection, 9 out of 14 patients with small-bowel Crohn's disease and in 2 out of 10 patients with Crohn's colitis. The 5 patients with small-bowel Crohn's disease and normal retention had either inactive disease or no radiological evidence of terminal ileal involvement. Measurements of the absorption of vitamin B12 did not discriminate between these groups, and there was very poor correlation between B12 and SeHCAT absorption (r = 0.506, P less than 0.05). There was extremely good correlation of SeHCAT retention measured using a wholebody counter with that measured using an uncollimated gamma camera (r = 0.96, P less than 0.001). The results suggest that SeHCAT retention may prove complementary to conventional methods of assessing small-bowel disease in patients with inflammatory bowel disease. As measurement by gamma camera is feasible, this test can be used in most departments of nuclear medicine.

A comparison between the use of a shadow shield whole body counter and an uncollimated gamma camera ain the assessment of the seven-day retention of SeHCAT.

We have compared the 7-day retention of the radioisotope bile salt analogue SeHCAT (75Se-23-selena-25-homotaurocholate), by whole body counting and by uncollimated gamma camera measurement, in phantoms and in 25 patients with inflammatory bowel disease. The results correlate with a linear correlation coefficient of 0.96. An uncollimated gamma camera can be used to assess bile acid malabsorption when a whole body radioactivity monitor is not available.

New approach to the localisation of phaeochromocytoma: imaging with iodine-131-meta-iodobenzylguanidine.

Thirty eight patients with known or suspected phaeochromocytoma were studied by radioisotope imaging after intravenous administration of iodine-131-meta- iodobenzylguanidine (131I- mIBG ), a radiopharmaceutical which has affinity for chromaffin tumours. Seventeen positive results (including one false positive) and 21 negative results (including two false negatives) were obtained. Clinical accuracy was 92%. Urinary noradrenaline concentrations were raised in all patients with confirmed phaeochromocytoma. These findings show that 131I- mIBG is of value in localising and assessing the extent of chromaffin tumours.

Poor sensitivity of multiple-gated blood-pool imaging in diagnosing left ventricular aneurysms.

A study was carried out to determine the accuracy of multiple-gated blood-pool imaging in diagnosing left ventricular aneurysm. Fifteen patients with an aneurysm and 17 with left ventricular hypokinesia were studied by contrast ventriculography and multiple-gated blood-pool imaging. The results of blood-pool imaging were examined blind by five independent observers, the results of contrast ventriculography being used as the standard. The mean sensitivity of the procedure was 56%, the specificity 61%, and diagnostic accuracy 59%. These results indicate that contrast ventriculography remains the best method for diagnosing left ventricular aneurysms. Moreover, ventriculography provides additional information-for example, on wall thickness-not provided by multiple-gated blood-pool imaging.

Assessment of progression of secondary bone lesions following cancer of the breast or prostate using serial radionuclide imaging.

A serial study on 32 patients with bone metastases following cancer of the breast or prostate was performed over three years. Up to ten sets of images (average of four) per patient were obtained during this period using 99Tcm methylene diphosphonate as the radiopharmaceutical. Ninety-three paired serial images of individual lesions were qualitatively assessed for change by three physicians in nuclear medicine and the results were compared with the quantitative results from computer analysis. The reproducibility of the quantitative approach was determined by the analysis of 20 paired lesions by three physicists. It was found that quantitative changes in uptake of less than 20% between images were generally not detected by the medical observers; a change of 41% had only a 95% probability of being identified as change by the physicians. Although much more reproducible in determining changes in individual lesions, the quantitative approach was found to be inferior to the qualitative assessment of overall change in the majority of cases which involve multiple lesions. The basic assumption that uptake varies proportionally with progression of the bone lesion is discussed an is considered in some instances to be untenable. The conclusion is drawn that the determination of progression from changes of uptake in longstanding lesions is uncertain and is subsidiary in importance to the detection of new lesions.