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Biomedical subjects

A K Dixon

Publications and source records attributed to A K Dixon.

At least 19 recordsLinked to original sources
PubMed1992

Degenerative disc disease in the lumbar spine: another cause for focally reduced activity on marrow scintigraphy.

A patient is presented in whom a focal reduction in marrow activity in the lumbar spine on both leucocyte and nanocolloid marrow scintigraphy was subsequently shown to be due to fatty infiltration of marrow in association with disc degeneration. Degenerative disease in the lumbar spine has not been previously described as a cause of abnormal bone marrow distribution by such means and needs to distinguished from a more serious pathology, such as malignant infiltration and vertebral infection, which it may mimic. In a retrospective review of 33 nanocolloid bone marrow and 117 leucocyte scintigrams, 8 showed a degree of reduced marrow activity in the lumbar spine consistent with that caused by degenerative changes.

Adult↗
PubMed1992

Bleomycin lung: the effect of different chemotherapeutic regimens.

A review of hard-copy computed tomography (CT) images of patients who had undergone chemotherapy for testicular teratoma revealed that the incidence of lung toxicity appeared to be lower in those who had received bleomycin by slow infusion [EBCi (3) regimen, etoposide/bleomycin/cisplatin] rather than by intravenous bolus [PVB regimen, cisplatin/vinblastine/bleomycin; BEP (5) regimen, bleomycin/etoposide/cisplatin]. This difference reached statistical significance only for PVB vs EBCi (3) (t = 2.63, P less than 0.01). Nevertheless, in view of continuing reports of mortality resulting from bleomycin-induced pulmonary fibrosis in patients receiving the drug by i.v. bolus, further exploration of these results is clearly justified.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Spiral versus conventional CT in soft tissue diagnosis.

Spiral volumetric computed tomography (SVCT) has been predicted to improve vascular and organ enhancement with little effect on image quality. To see if this was the case, we studied 100 patients referred for computed tomography where we would normally have performed dynamic incremental computed tomography (DICT). Patients were randomly allocated to undergo either standard DICT or SVCT. The resulting images were analysed for overall quality, the degree of contrast medium enhancement and the extent of artefacts associated with the technique. No statistically significant difference in overall image quality between SVCT and DICT was found, apart from images of the hepatic parenchyma where the quality was significantly worse on SVCT (P < 0.05) due to the low mA permissible. Contrast enhancement was better with SVCT, although only for the thorax (P < 0.01) and the group taken as a whole (P < 0.01) did this improvement reach statistical significance. There was no statistically significant difference between the extent of artefacts observed in the two techniques. As expected, all acquisition times were shorter using SVCT. The benefits of SVCT have been well described and include the absolute contiguity of the reconstructed images and the ability to obtain many images at peak contrast enhancement. We have confirmed the latter effect. We are now also satisfied that there is no appreciable loss of overall image quality except where large volumes of solid tissue are being examined (e.g. liver).

Algorithms↗
PubMed1992

CT-guided drainage of pelvic abscesses: the peranal transrectal approach.

Five patients with deep pelvic abscesses underwent computed tomography (CT)-guided catheter drainage using a transrectal approach. The use of an outer removable plastic sheath over the catheter to facilitate positioning and prevent inadvertent damage to the mucosal wall is described. This new approach using CT guidance is discussed and the alternative routes reviewed.

Abscess↗
PubMed1992

Clinico-radiological meetings: are they worthwhile?

The proceedings of 22 clinico-radiological meetings were analysed in order to assess some aspects of their benefits and cost. The mean duration of each meeting was 30.4 min. On average, the clinical and radiological details of eight patients were discussed at each meeting. The mean number of changes in the leading diagnosis was 1.6 per meeting, and a mean of 1.9 management decisions were made. A mean of 1.6 further radiological tests were recommended, offset by a mean of 0.7 scheduled investigations which were deemed no longer necessary. The cost of the salaries of the staff attending each meeting amounted to 73.82 pounds. Thus the cost of a revised leading diagnosis was calculated at 46.14 pounds whilst that of a management decision came to 38.85 pounds. The assumed educational benefits of these meetings and inevitable lost opportunity costs were not analysed.

Cost-Benefit Analysis↗
PubMed1992

Computed tomography in blunt abdominal trauma: an analysis of clinical management and radiological findings.

We have retrospectively assessed the computed tomography (CT) findings in 92 patients suffering severe blunt abdominal trauma. Surgical findings and clinical follow-up were correlated with the CT findings. In nine patients CT was first used after emergency surgery and provided baseline data which was useful for further management. In two patients CT did not demonstrate small hepatic lacerations seen during previous surgery. No deaths were recorded. In 16 patients surgery followed CT within 24 h; there was good correlation between the CT and operative findings in 10 patients. However, CT failed to detect significant solid organ injury in five patients and was misleading (false positive) in another patient. There were two deaths amongst these 16 patients. Sixty-seven haemodynamically stable patients were initially managed non-operatively. Fifteen of these 67 patients had normal CT examinations; only one had subsequent laparotomy (for reasons unconnected with the trauma) where no injury was detected; there were no deaths. Of the 52 patients with an abnormal CT examination, 43 were successfully managed non-operatively. There were three deaths, including one where an injury missed at CT contributed to the demise of the patient. After an initial trial of non-operative management, the remaining six patients went to surgery where there was good concordance with the CT findings except for one missed renal injury. Active non-operative management of blunt abdominal trauma is widely accepted in haemodynamically stable patients and this report shows how CT supports this policy of surgical restraint in such cases. However, on review CT missed 13 injuries in nine patients overall; stricter attention to technique and better equipment may lead to improved results in the future.

Abdominal Injuries↗
PubMed1992

Computed tomography in abdominal trauma: an audit of usage and image quality.

The use and quality of computed tomography (CT) in the evaluation of blunt abdominal trauma has been assessed by a retrospective review of 122 patients referred in the first 8 years following the installation of CT of the body. The referral patterns were analysed, and the quality of the images was assessed, with particular reference to unsatisfactory (unacceptable or poor) images. Referrals increased over the 8 years following installation. A large proportion of these examinations were performed outside normal working hours (58/122, 48%). In 64 out of 122 (52%) of examinations the images were considered of unsatisfactory quality with inadequate use of intravenous contrast medium cited as the most common cause for unsatisfactory examinations. Image quality did not improve with time. Image quality was unsatisfactory in a larger proportion of those examinations performed outside normal working hours (35/58, 60%) than those during the routine working day (29/64, 45%), although this difference did not reach statistical significance (0.1 greater than p greater than 0.05). Fewer unsatisfactory examinations were produced by a system dedicated to body CT (31/74, 42%) than by a neuroradiological system (33/48, 69%) (p less than 0.01). The proportion of unsatisfactory abdominal examinations was lower when the CT study concentrated on the abdomen (26/65, 40%) than when multiple regions (head, chest, abdomen, etc.) were examined (38/57, 67%) (p less than 0.01). This audit revealed many unsatisfactory examinations. In order to complete the audit loop we have addressed many of the contributory factors. A new CT system now provides images of high quality and is used for all abdominal work. Guidelines, which describe an optimized technique, have been issued to radiographers and radiologists. In particular, we have emphasized that there is no place for a poorly supervised "quick look" at the abdomen following a cranial or thoracic study.

Abdominal Injuries↗
PubMed1992

Successful treatment of bone marrow failure in Gaucher's disease with low-dose modified glucocerebrosidase.

We report the beneficial effects of enzyme replacement therapy with mannose-terminated human glucocerebrosidase ('Ceredase') in a patient suffering from transfusion-dependent bone marrow failure due to Gaucher's disease. Treatment with low-dose enzyme infusions, given twice weekly, rapidly reversed the haematopoietic failure and incapacitating skeletal disease. It appears likely that prior splenectomy favourably influenced the response to this therapy.

Bone Marrow Diseases↗
PubMed1991

Colour perfusion imaging: a new application of computed tomography.

We describe a new application for imaging with computed tomography (CT) in which a quantifiable map of tissue perfusion is created and displayed by means of a colour scale. A rapid sequence of images is acquired without table movement immediately after a bolus intravenous injection of radiographic contrast medium. The rate of enhancement in each pixel within the chosen slice can then be used to determine perfusion. The technique provides a quantifiable display of regional perfusion combined with the high spatial resolution afforded by CT.

Color↗
PubMed1991

Magnetic resonance imaging of the head and spine: effective for the clinician or the patient?

OBJECTIVES: To test how the results of magnetic resonance imaging influence clinicians' diagnoses and management plans for patients with cranial and spinal problems and to assess changes in the quality of life of these patients. DESIGN: Survey of patients undergoing cranial and spinal magnetic resonance imaging with questionnaires about diagnoses and intended management plans before and after imaging and quality of life questionnaires at the time of imaging and again four months later. SETTING: Regional magnetic resonance imaging and spectroscopy unit. SUBJECTS: 100 consecutive patients referred for cranial imaging in early 1989; 100 similar patients referred for spinal imaging. MAIN OUTCOME MEASURES: Changes in clinicians' leading diagnoses after magnetic resonance imaging and their confidence in these diagnoses; changes in intended management plans; assessment of the contribution to the future management of the patient; changes in patients' quality of life. RESULTS: Magnetic resonance imaging altered the clinicians' leading diagnoses in 35 of 169 (21%) cases. The clinicians became more confident about their leading diagnoses in 90 of 167 (54%). There was a change in management plan in 113 of 182 (62%). The clinicians considered that magnetic resonance imaging made an important contribution to management in 119 of 162 (73%) patients. Overall, the patients' quality of life was unchanged at the four month assessment. CONCLUSIONS: Magnetic resonance imaging of patients with cranial and spinal problems influences clinicians' diagnoses and management plans, but the quality of life of these patients remains unchanged.

Adolescent↗
PubMed1991

Surgical restraint in the management of liver trauma.

Previous experience in Cambridge in the management of liver trauma has led to the evolution of a protocol for surgical intervention to secure control of haemorrhage from the injured liver. We report 80 cases of liver trauma including 12 who were initially managed non-operatively; three of these subsequently required operation. Of the 80, all but five suffered blunt abdominal trauma. Perihepatic packing was used to manage 29 patients, of whom 21 were initially treated elsewhere before being transferred to Cambridge. Six of these required a hemihepatectomy at subsequent exploration. Of the 39 patients who underwent urgent laparotomy and definitive surgery, 11 (28 per cent) died; only three out of 29 (10 per cent) died after initial packing. Only one death from hepatic complications occurred after packing and subsequent transfer.

Hemorrhage↗
PubMed1991

Localized in vivo proton spectroscopy of the human kidney.

In vivo 1H spectroscopy using the STEAM sequence for localization has been applied to the human kidney in normal volunteers and subjects with successful renal transplants. We show that, within the resolution of our measurements, trimethylamines are present in the spectra from some of the subjects and absent from others. The prominent peak seen at 5.8 ppm in the spectrum is identified as that from urea and not lipid, as previously suggested.

Humans↗
PubMed1991

Magnetic resonance imaging: when is one sequence sufficient?

We have studied 100 patients undergoing magnetic resonance imaging (MRI) in eight well-defined clinical problems. The relative values of the clinical details and the initial imaging sequence in reaching the final MR diagnoses were assessed. For each patient, two radiologists independently predicted the likely radiological findings from the clinical details. They then assessed the radiological appearances shown by the initial imaging sequence (which was chosen according to the clinical problem). Lastly, they made a final interpretation using all the available information. Prediction of likely radiological abnormalities from the clinical details proved unreliable. However, the radiological assessment of the initial imaging sequence was reliable for clinical problems related to the pituitary fossa, posterior fossa, internal auditory meatus and for suspected multiple sclerosis. In these patient groups additional sequences might be reserved for those with equivocal findings. Conversely, assessment of the initial imaging sequence proved unreliable compared with the full radiological assessment for clinical problems in the lumbar spine, the axilla and the knee. This study has led us to reduce the number of sequences performed for some clinical problems, with a commensurate increase in the throughput of patients.

Clinical Competence↗
PubMed1991

Measurement of regional left ventricular function using labelled magnetic resonance imaging.

A technique for assessing regional left ventricular function using magnetic resonance imaging is described. Spatial modulation of magnetization (SPAMM) is effected immediately before images are obtained at various intervals during the cardiac cycle using a modified field echo even rephasing technique (FEER). By performing such modulation in two planes, a grid pattern of labelling can be produced across the image. On the resulting labelled short axis images of the left ventricle, the systolic increase in thickness (thickening) and decrease in length (shortening) of different regions of myocardium can then be measured. The findings in five normal volunteers are presented. Radial shortening was twice as great in the endocardium (mean 20.4%, standard deviation (SD) 5.7) than in the epicardium (mean 10.2%, SD 5.5) and appears to offer more promise as a marker of regional function than simple thickening (mean 9.8%, SD 13.6).

Adult↗
PubMed1990

Bone density distribution within the femoral head and neck. An examination by high-resolution computed tomography.

The upper portions of three cadaveric femora were examined by high-resolution computed tomography. Analysis of the resulting images provided both quantitative and spatial distributions of bone density within the femoral head and neck. The information obtained provides new insights into aspects of proximal femoral architecture for both normal and osteoporotic bone. The study also points the way towards a clinical technique for measuring the material properties of proximal femoral bone.

Absorptiometry, Photon↗
PubMed1990

Axillary fibrosis or recurrent tumour. An MRI study in breast cancer.

Magnetic resonance imaging was performed in 35 patients with breast carcinoma in an attempt to elucidate the cause for arm oedema or neurological symptoms. In each patient the clinician was asked to predict at the outset whether tumour recurrence or radiation fibrosis was more likely on clinical grounds. MRI demonstrated features compatible with fibrosis in 21 and tumour recurrence in 10; the MRI findings were equivocal in four patients. The range of these appearances is described and demonstrated. The MRI findings were at gross variance with the clinical opinion in 10 patients, upgrading eight patients to tumour recurrence and downgrading two to radiation fibrosis. Although histological confirmation is only available in three patients, corroborative evidence (that is repeat MRI, clinical follow up) is presented which suggests that the MRI interpretation was correct in the remaining patients. MRI can provide a working diagnosis in these patients; this allows a more rational approach to treatment than a diagnosis based on clinical examination alone.

Adult↗
PubMed1990

Problems in the management of testicular seminoma associated with a horseshoe kidney.

Four patients with seminoma of the testis and coexisting horseshoe kidney are presented. Three patients had stage one disease, which would conventionally be managed by abdominal nodal irradiation. However, because of the risk of radiation nephritis, a surveillance policy was adopted with regular computed tomography (CT). Two of these three patients have relapsed and are disease free after chemotherapy. The fourth patient had Stage IIC disease which initially responded to combined radiotherapy and chemotherapy. This patient's disease relapsed and he died despite further treatment. Because of the altered retroperitoneal anatomy, CT interpretation must be made with special care.

Adult↗