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Magnetic resonance imaging of the adrenal
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CLINICAL RADIOLOGY
RADIONUCLIDE IMAGING WITH mlBG D. ACKERY
Southampton General Hospital, Southampton Radioiodinated [I]m-iodobenzyl guanidine (mIBG) has been found to be both sensitive and specific for the localisation of phaeochromocytoma since it was first used in man at Michigan in 1981. Following slow intravenous administration, this radiopharmaceutical follows a noradrenaline pathway in the body and shows concentration in a number of normal tissues. Anterior and posterior gamma camera imaging is carried out over a period of up to 3 days using iodine-131 or iodine-123 labelling of mlBG. Phaeochromocytorna usually shows intense uptake above the normal background pattern. The functional radionuclide images given with mlBG complement those of computed tomography (or other radiological techniques) for the diagnosis and management of phaeochromocytoma. The investigation is indicated for those patients with clinical and biochemical evidence of raised catecholamine output, and the results are particularly valuable for extra-adrenal, multifocal and malignant forms of the turnout. mlBG imaging also has a place in the management of neuroblastoma and carcinoid tumours, High level activity is used for treating both these tumours and malignant phaeochromocytoma.
W H I C H H Y P E R T H Y R O I D P A T I E N T S S H O U L D BE S C A N N E D AND W H Y ?
to the head. Late complications were not encountered in 26 other acromegalic patients treated over the past 25 years or in 130 patients treated in conjunction with Professor Lindsay Symon.
MAGNETIC RESONANCE IMAGING OF THE ADRENAL G. M. BYDDER
Royal Postgraduate Medical School, London Magnetic resonance imaging (MRI) of the abdomen has now been in use for over 7 years. While progress has been slower than in the central nervous system some interesting results are now appearing. Adrenal tumours of greater than 1 cm can be visualised and measurements of signal intensity with T2 weighted sequences seem of value in discriminating between non-hyperfunctioning adenomas, adenomas and metastases. While other conditions such as hyperplasia, cysts and carcinoma can be demonstrated, assessment of the functional state of turnouts appears the most useful single application to date. Carcinomas and neuroblastomas can be staged and coronal and sagittal imaging is useful in this context.
SURGICAL MANAGEMENT OF PITUITARY TUMOURS LINDSAY SYMON
Institute of Neurology, London WCIN 3BG
I. FOGELMAN
Guy's Hospital, London Hyperthyroidism is usually caused by Graves' disease, and a thyroid scan will seldom provide additional diagnostic information in such cases whe n a diffuse goitre is present. However, the thyroid may not be palpable in 1 to 3% of cases. When single or multiple thyroid nodules are palpated, a thyroid scan is crucial in establishing an accurate diagnosis as it is not otherwise possible to differentiate between Plummer's disease and Graves' disease developing in a multinodular gland. Rarely, a dominant non-functioning nodule will be present in Graves' disease, which has a reported increased incidence of malignancy. If thyrotoxic patients are to be treated with radioiodine, thyroid imaging with tracer quantification can replace a 24 h iodine-131 uptake measurement. This has the advantages that the patients are required to attend only once, and the gland size can be measured. In addition, visual confirmation of tracer uptake of the thyroid is obtained and patients with thyroiditis will not receive inappropriate therapy.
Up until 10 to 15 years ago the majority of operations carried out for pituitary tumour were occasioned by visual failure. In certain specialised centres associated with endocrinologists, a small number of patients with Cushing's syndrome and a rather larger number of patients with acromegaly would proceed to surgery, but in a majority of standard neurosurgical units, operations for acromegaly or for Cushing's syndrome would occasion less than 10% of the pituitary work. The realisation that somewhere around 70% of so-called inactive adenomas may secrete prolactin and the recognition of the syndrome of galactorrhoea and of amenorrhoea as having a central pituitary cause has changed the spectrum of pituitary surgery. Surgery for pituitary turnouts, therefore, has now evolved into two portions. Surgery for visual failure, and surgery for endocrinopathy. In one case we may be dealing with very large pituitary masses, and in the other, lesions which declare themselves early and confined to the pituitary gland itself, may be very small, The latter lesions are best dealt with by the trans-sphenoidal route. The management of the larger ones remains unsettled. "Experience with radical suprasellar surgery in over 300 large pituitary lesions is detailed.
R A D I O T H E R A P Y IN T E A M A P P R O A C H T O MANAGEMENT
OF ENDOCRINE DISEASE C. D. COLLINS
PITUITARY A D E N O M A S - P O S T - T R E A T M E N T APPEARANCES
St Thomas' Hospital, London
The National Hospital, London WC1N 3BG
Pituitary tumours encountered in endocrine disease are mainly slow growing and so are relatively radio-insensitive. Radiotherapy is therefore not the primary treatment of choice, especially if the presenting symptom is impaired vision. It is mainly used post-operatively to reduce or delay local recurrence in cases of chromophobe adenomas, or to help reduce still further the abnormal hormone level in those tumours that are contributing to the endocrine disease. Treatment is not started until the patient has made a full and stable post-operative recovery. It is planned individually and the target volume treated is kept as small as possible depending on the operative and radiological findings. A three-field technique is employed, with the patient immobilised in a plastic shell, to give a uniform dosage with full isodosimetry, taking care to avoid excessive dose to the optical pathways, brain stem and temporal lobes. A dose of 3600 cGy given in 12 fractions over approximately 4 weeks, that is 300 cGy per fraction or a TDF of 68. There are few immediate side-effects apart from some patients experiencing slight nausea, which is accentuated if they are currently taking bromocriptine, and a temporary loss of hair in all patients at the site of the portal of entry of the radiation beam. Regrowth of the hair occurs within 2 to 3 months. Late side-effects have been encountered with varying degrees of hypopituitarism, and one acromegalic patient who received our present dosage schedule subsequently became blind after a severe blow
Normal early post-surgical appearances
B. E. KENDALL
Haemorrhagic exudate, hyperintense on CT and giving high signal on T1 weighted MRI, is present along the approach to the pituitary. Air in the sella may stay for prolonged periods if a floor defect remains open. Exudate within the tumour bed only gradually absorbs during 3 months after surgery and should not be misinterpreted as residual tumour. Muscle, fat or clot occluding the surgical defect may induce tissue reaction with enhancement. Foreign material may persist as an unenhancing hyperdensity for years. The size of the sella reduces and the walls reconstitute. If the adenoma alone is removed, the pituitary may appear normal. If the adenoma cavity is filled with fluid, gelfoam, muscle or fat, this may remain as a low density, gradually decreasing in volume. Removal of the pituitary or large adenomas may allow intrasellar herniation of the chiasmatic cistern, outlining the infundibulum; the optic chiasm may be drawn into the sella and distorted.
Pituitary post-surgical complications 1. Haematoma: a symptomatic perisellar mass larger than the preoperative tumour should be considered significant. 2. Visible bleeding or carotico-cavernous fistuala: aneurysms are not infrequent in association with pituitary tumours; also, medially placed arteries may be damaged. 3. Cerebral infarction: may result from arterial damage.
CLINICAL RADIOLOGY
RADIONUCLIDE IMAGING WITH mlBG D. ACKERY
Southampton General Hospital, Southampton Radioiodinated [I]m-iodobenzyl guanidine (mIBG) has been found to be both sensitive and specific for the localisation of phaeochromocytoma since it was first used in man at Michigan in 1981. Following slow intravenous administration, this radiopharmaceutical follows a noradrenaline pathway in the body and shows concentration in a number of normal tissues. Anterior and posterior gamma camera imaging is carried out over a period of up to 3 days using iodine-131 or iodine-123 labelling of mlBG. Phaeochromocytorna usually shows intense uptake above the normal background pattern. The functional radionuclide images given with mlBG complement those of computed tomography (or other radiological techniques) for the diagnosis and management of phaeochromocytoma. The investigation is indicated for those patients with clinical and biochemical evidence of raised catecholamine output, and the results are particularly valuable for extra-adrenal, multifocal and malignant forms of the turnout. mlBG imaging also has a place in the management of neuroblastoma and carcinoid tumours, High level activity is used for treating both these tumours and malignant phaeochromocytoma.
W H I C H H Y P E R T H Y R O I D P A T I E N T S S H O U L D BE S C A N N E D AND W H Y ?
to the head. Late complications were not encountered in 26 other acromegalic patients treated over the past 25 years or in 130 patients treated in conjunction with Professor Lindsay Symon.
MAGNETIC RESONANCE IMAGING OF THE ADRENAL G. M. BYDDER
Royal Postgraduate Medical School, London Magnetic resonance imaging (MRI) of the abdomen has now been in use for over 7 years. While progress has been slower than in the central nervous system some interesting results are now appearing. Adrenal tumours of greater than 1 cm can be visualised and measurements of signal intensity with T2 weighted sequences seem of value in discriminating between non-hyperfunctioning adenomas, adenomas and metastases. While other conditions such as hyperplasia, cysts and carcinoma can be demonstrated, assessment of the functional state of turnouts appears the most useful single application to date. Carcinomas and neuroblastomas can be staged and coronal and sagittal imaging is useful in this context.
SURGICAL MANAGEMENT OF PITUITARY TUMOURS LINDSAY SYMON
Institute of Neurology, London WCIN 3BG
I. FOGELMAN
Guy's Hospital, London Hyperthyroidism is usually caused by Graves' disease, and a thyroid scan will seldom provide additional diagnostic information in such cases whe n a diffuse goitre is present. However, the thyroid may not be palpable in 1 to 3% of cases. When single or multiple thyroid nodules are palpated, a thyroid scan is crucial in establishing an accurate diagnosis as it is not otherwise possible to differentiate between Plummer's disease and Graves' disease developing in a multinodular gland. Rarely, a dominant non-functioning nodule will be present in Graves' disease, which has a reported increased incidence of malignancy. If thyrotoxic patients are to be treated with radioiodine, thyroid imaging with tracer quantification can replace a 24 h iodine-131 uptake measurement. This has the advantages that the patients are required to attend only once, and the gland size can be measured. In addition, visual confirmation of tracer uptake of the thyroid is obtained and patients with thyroiditis will not receive inappropriate therapy.
Up until 10 to 15 years ago the majority of operations carried out for pituitary tumour were occasioned by visual failure. In certain specialised centres associated with endocrinologists, a small number of patients with Cushing's syndrome and a rather larger number of patients with acromegaly would proceed to surgery, but in a majority of standard neurosurgical units, operations for acromegaly or for Cushing's syndrome would occasion less than 10% of the pituitary work. The realisation that somewhere around 70% of so-called inactive adenomas may secrete prolactin and the recognition of the syndrome of galactorrhoea and of amenorrhoea as having a central pituitary cause has changed the spectrum of pituitary surgery. Surgery for pituitary turnouts, therefore, has now evolved into two portions. Surgery for visual failure, and surgery for endocrinopathy. In one case we may be dealing with very large pituitary masses, and in the other, lesions which declare themselves early and confined to the pituitary gland itself, may be very small, The latter lesions are best dealt with by the trans-sphenoidal route. The management of the larger ones remains unsettled. "Experience with radical suprasellar surgery in over 300 large pituitary lesions is detailed.
R A D I O T H E R A P Y IN T E A M A P P R O A C H T O MANAGEMENT
OF ENDOCRINE DISEASE C. D. COLLINS
PITUITARY A D E N O M A S - P O S T - T R E A T M E N T APPEARANCES
St Thomas' Hospital, London
The National Hospital, London WC1N 3BG
Pituitary tumours encountered in endocrine disease are mainly slow growing and so are relatively radio-insensitive. Radiotherapy is therefore not the primary treatment of choice, especially if the presenting symptom is impaired vision. It is mainly used post-operatively to reduce or delay local recurrence in cases of chromophobe adenomas, or to help reduce still further the abnormal hormone level in those tumours that are contributing to the endocrine disease. Treatment is not started until the patient has made a full and stable post-operative recovery. It is planned individually and the target volume treated is kept as small as possible depending on the operative and radiological findings. A three-field technique is employed, with the patient immobilised in a plastic shell, to give a uniform dosage with full isodosimetry, taking care to avoid excessive dose to the optical pathways, brain stem and temporal lobes. A dose of 3600 cGy given in 12 fractions over approximately 4 weeks, that is 300 cGy per fraction or a TDF of 68. There are few immediate side-effects apart from some patients experiencing slight nausea, which is accentuated if they are currently taking bromocriptine, and a temporary loss of hair in all patients at the site of the portal of entry of the radiation beam. Regrowth of the hair occurs within 2 to 3 months. Late side-effects have been encountered with varying degrees of hypopituitarism, and one acromegalic patient who received our present dosage schedule subsequently became blind after a severe blow
Normal early post-surgical appearances
B. E. KENDALL
Haemorrhagic exudate, hyperintense on CT and giving high signal on T1 weighted MRI, is present along the approach to the pituitary. Air in the sella may stay for prolonged periods if a floor defect remains open. Exudate within the tumour bed only gradually absorbs during 3 months after surgery and should not be misinterpreted as residual tumour. Muscle, fat or clot occluding the surgical defect may induce tissue reaction with enhancement. Foreign material may persist as an unenhancing hyperdensity for years. The size of the sella reduces and the walls reconstitute. If the adenoma alone is removed, the pituitary may appear normal. If the adenoma cavity is filled with fluid, gelfoam, muscle or fat, this may remain as a low density, gradually decreasing in volume. Removal of the pituitary or large adenomas may allow intrasellar herniation of the chiasmatic cistern, outlining the infundibulum; the optic chiasm may be drawn into the sella and distorted.
Pituitary post-surgical complications 1. Haematoma: a symptomatic perisellar mass larger than the preoperative tumour should be considered significant. 2. Visible bleeding or carotico-cavernous fistuala: aneurysms are not infrequent in association with pituitary tumours; also, medially placed arteries may be damaged. 3. Cerebral infarction: may result from arterial damage.