Biomedical subjects
M N Maisey
Publications and source records attributed to M N Maisey.
Magnetic resonance imaging of hearts with atrioventricular valve atresia or double inlet ventricle.
OBJECTIVE: To investigate the effectiveness and limitations of magnetic resonance imaging in defining cardiac anatomy in patients with double inlet ventricle or atrioventricular valve atresia. DESIGN: Magnetic resonance images were reviewed retrospectively without reference to other morphological data. SETTING: A tertiary referral centre for paediatric cardiology. PATIENTS: 18 patients (aged 8 days to 27 years) with a suspected univentricular atrioventricular connection. METHODS: Imaging by a 1.5 T whole body magnetic resonance system with imaging planes adjusted to individual patient anatomy to best define the cardiac morphology. A complete sequential diagnosis obtained from an independent interpretation of the images was compared with the diagnosis obtained from cross sectional echocardiography and angiocardiography. RESULTS: There was substantial accord between the diagnosis from magnetic resonance alone and that from other methods. In the six instances where there was not accord the magnetic resonance diagnosis was considered to be correct in two cases and incorrect in three cases. In the remaining case no consensus could be reached. In eight patients magnetic resonance imaging provided anatomical information additional to that from other methods. The strengths of magnetic resonance were in imaging the pulmonary arteries and their abnormalities and identifying juxtaposed atrial appendanges but there were some deficiencies in identifying Blalock-Taussig shunts. CONCLUSION: Magnetic resonance imaging provided detailed information about all aspects of cardiac morphology in patients with a suspected diagnosis of univentricular atrioventricular connection. Often it provided additional information to echocardiography. Its use in selected patients should give valuable complementary information.
Modern imaging methods in oncology.
Modern imaging methods are very important in the management of patients with cancer and of their disease. It is vital that clinicians treating them understand the relevance of different imaging techniques for specific applications, so that the best choice can be made to aid diagnosis and monitor response to treatment. This review briefly covers the development and principles of the diverse imaging methods available, from the discovery of x-rays by Röntgen in 1895 to the recent techniques of magnetic resonance and positron emission tomography. The authors endeavour to point out the strengths and weaknesses of each method, using clinical examples where appropriate. Finally, future developments are discussed. It is hoped that this review will aid clinicians diagnosing and treating cancer patients to choose the most suitable imaging method for their patients from among the vast array available.
Gallium-67 scanning in pyrexia of unknown origin.
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Cold pressor test in detection of coronary heart-disease and cardiomyopathy using technetium-99m gated blood-pool imaging.
50 normotensive subjects (22 controls with no cardiac disease, 24 patients with coronary heart-disease, and 4 with early cardiomyopathy) were investigated with gated cardiac blood-pool scintigraphy before and during cold pressor stimulation. The controls had no change or a significant rise (p less than 0.005) in left ventricular ejection fraction and preserved normal myocardial-wall motion, whereas patients with coronary-artery disease or cardiomyopathy had a significant fall (p less than 0.001) in left ventricular ejection fraction and many developed abnormal regional wall motion despite the absence of angina pectoris. Cold pressor gated cardiac blood-pool studies were more sensitive than single-lead exercise electrocardiography (p = 0.03) in the detection of patients with severe coronary-artery disease without previous myocardial infarction.
Serum thyroglobulin concentrations and whole-body radioiodine scan in follow-up of differentiated thyroid cancer after thyroid ablation.
Measurement of serum thyroglobulin (Tg) concentrations and whole-body radioiodine scan were performed simultaneously during follow-up of 32 patients with differentiated thyroid cancer who had undergone thyroid ablation by operation and radioiodine. Almost all patients in whom serum Tg was undetectable had normal scans. Concentrations exceeding 50 ng/ml were invariably associated with residual or metastatic tumour uptake in the scan. Out of 21 observations of detectable values below 50 ng/ml, 14 were in patients whose scans showed subclinical or sub-radiological tumour uptake and seven in patients with normal scans. The sensitivity of serum Tg as a tumour marker compared favourably to that of the whole-body scan. A scan is unnecessary when serum Tg is undetectable, but in patients with detectable serum Tg concentrations, particularly if these are below 50 ng/ml, a scan is important to assess and localise tumour uptake of iodine before advising treatmet with iodine-131.
Stress lesions of the lower leg and foot.
Technetium 99 methylene diphosphonate scans were performed on 32 patients with suspected stress fractures. Twenty-six patients had abnormal scans, 13 had abnormal X-rays and on these only nine had either fresh periosteal new bone and/or a fracture line. A logical approach of the use of X-ray and radionuclide techniques in patient management is suggested.
Standard dose 131I therapy for hyperthyroidism caused by autonomously functioning thyroid nodules.
Thirty-one patients with hyperthyroidism shown on scintigram to have autonomously functioning thyroid nodules were treated with a standard dose of 15 milliocuries (mCi) of 131I. Of thirty patients who have been followed up for a least 6 months to over 3 years, all but one patient were euthyroid after a single dose. Repeat scintigram and Thyrotropin Releasing Hormone (TRH) test after therapy confirmed that twenty-five patients were cured of the disease. Only one patient developed hypothyroidism. This simplified standard dose regimen of radioiodine is effective in the treatment of hyperthyroidism caused by autonomously functioning nodules and is not complicated by the high incidence of hypothyroidism that is observed following radioiodine therapy of Graves' disease.
Posterior intrathoracic goitre as a cause of thyrotoxicosis.
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Serial quantitative imaging with 99Tcm-DTPA in pediatric renal transplantation.
Three hundred and fifty-eight renal imaging studies with quantitation of renal perfusion were performed following injection of 99Tcm-DTPA in 22 children aged 6--15 years with renal transplants. In 58 of 62 scans performed at the onset of a rejection episode, renal perfusion was decreased. This was the only feature of rejection in 6 episodes, in 5 of which the patient was oliguric due to post-operative acute tubular necrosis. In 4 episodes perfusion fell, but antirejection treatment was not given as a repeat scan was normal. On 18 occasions the plasma creatinine concentration (Pc) rose, but the scan was unchanged; no treatment was given and repeat Pc was normal. Three patients had a ureteric obstruction and 2 patients a lymphocoele detected from the images. There was no morbidity. Sequential renal scintigraphy was valuable in the early diagnosis of rejection and in the avoidance of unnecessary therapy.
Quantitative lacrimal scintillography.
In a study of 100 asymptomatic lacrimal systems, we have found that quantitative lacrimal scintillography provided a sensitive and reproduceable test of canalicular function. This technique, at the present time, appears to have no role in the clinical evaluation of tear passage through the nasolacrimal duct to the nose. A revision of the currently accepted theory of lacrimal drainage is proposed. Lacrimal drainage is best approached as a bimodel system. The first part, from conjunctiva to lacrimal sac, is dependent upon the "lacrimal pump." The second part, by which tears drain from the sac to the inferior meatus of the nose at basal tearflow levels, is dependent on gravity and the resistance of the nasolacrimal duct.
Hypothyroidism in children with cystinosis.
Eight children with cystinosis (3 with renal transplants, 2 on maintenance haemodialysis, 2 with chronic renal failure, and one with normal renal function) were studied for evidence of hypothyroidism, and compared with a control group of children with chronic renal failure due to other causes. Abnormal thyroid function was present in all the cystinotic patients: thyroxine (T4) low in 1, free thyroxine index (FTI) low in 2, thyroid-stimulating hormone (TSH) raised in 6; all had a supranormal TSH response to thyrotrophin-releasing hormone (TRH) stimulation, indicating impaired thyroid reserve compared with patients in the control group who had a depressed or normal TSH response. Increased growth velocity with thyroid supplementation occurred in only 2 patients, and the onset of puberty may have contributed to this improvement. Hypothyroidism is a common finding in cystinosis, and it is suggested that thyroxine treatment be started when the TSH concentration becomes raised.
Use of 99Tcm-DMSA as a static renal imaging agent.
The use of 99Tcm-labelled DMSA as a static renal imaging agent has been analyzed semi-quantitatively in 366 patients. Study with this agent proved to be of most value in patients with equivocal space-occupying lesions of the kidney, provided useful information in various destructive diseases of the kidney when used for determining divided renal function but was of little value in chronic renal failure. In 33 patients, the uptake of 99Tcm-DMSA at 3 h as a measure of divided renal function was compared with the uptake of 99Tcm-DTPA from 30 to 150 sec following injection and was found to correlate well. In a series of 7 dogs with induced unilateral renal impairment, divided function determined with 99Tcm-DMSA was found to correlate well with results obtained using 51Cr-EDTA.
Statements of the M.R.C. isotope panel.
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The appearances of renal transplant lymphocoeles during dynamic renal scintigraphy.
Eight patients are described in whom transplant lymphocoeles were drained. All had 99Tcm-DTPA dynamic renal scintigrams performed pre-operatively; five showed features of obstruction. Photon deficient areas on the scintigrams and bladder deformities were of particular value in detecting lymphocoeles.