Somatostatin receptor scintigraphy in the follow-up of patients with differentiated thyroid cancer

The aim of this study was to compare the results of somatostatin receptor scintigraphy (SRS) and of radioiodine scintigraphy in patients with metastatic differentiated thyroid carcinoma during L-thyroxine suppression therapy and after withdrawal. Twenty-five patients were studied: 16 patients had papillary cancer and 12 of them had metastatic disease; 9 patients had follicular cancer and 7 of these had known metastases. In 7 patients SRS was performed during thyroxine withdrawal, in 12 during thyroxine therapy within 9 months from radioiodine scintigraphy, in 6 others both during suppression therapy and after withdrawal. SRS was positive in 18 of 25 (72%) patients. It demonstrated lesions in 11 of 13 (85%) patients after thyroxine withdrawal and in 12 of 18 (67%) patients during thyroxine suppression. In 6 patients in whom a direct comparison was made before and after withdrawal, essentially the same information was obtained. Six of 8 (75%) patients with lesions that did not concentrate radioiodine showed uptake of labeled octreotide in these lesions. In 5 of 17 (29%) patients whose tumors concentrated radioiodine, no uptake was found during SRS.

CONCLUSIONS

1) in patients with metastatic differentiated thyroid carcinoma, tumor sites can be visualized using SRS; 2) there is no need to withdraw patients from suppression therapy in order to perform SRS; 3) in some patients whose lesions do concentrate labeled octreotide but not radioiodine, the use of somatostatin analogues labeled with (111)In or [90Y] can provide new therapeutic options.

[177Lu-DOTA(0),Tyr3] octreotate for somatostatin receptor-targeted radionuclide therapy

Receptor-targeted scintigraphy using radiolabeled somatostatin analogs such as octreotate is being used with great success to demonstrate the in vivo presence of somatostatin receptors on various tumors. A new and promising application for these analogs is radionuclide therapy. Radionuclides suitable for this application include the Auger electron-emitter (111)In and the beta-emitters (90)Y (high energy) and (177)Lu (low energy). We investigated [DOTA(0),Tyr(3)]octreotate, labeled with the lanthanide (177)Lu, in biodistribution and radionuclide therapy experiments using male Lewis rats bearing the somatostatin receptor-positive rat CA20948 pancreatic tumor. Biodistribution studies in Lewis rats showed the highest uptake in the rat pancreatic CA20948 tumor and sst(2)-positive organs, which include the adrenals, pituitary and pancreas, of [(177)Lu-DOTA(0),Tyr(3)]octreotate in comparison with (88)Y- and (111)In-labeled analogs. Kidney uptake of [(177)Lu-DOTA(0),Tyr(3)]octreotate could be reduced by approximately 40% by co-injection of 400 mg/kg D-lysine. In radionuclide therapy studies, a 100% cure rate was achieved in the groups of rats bearing small (< or =1 cm(2)) CA20948 tumors after 2 doses of 277.5 MBq or after a single dose of 555 MBq [(177)Lu-DOTA(0),Tyr(3)]octreotate. A cure rate of 75% was achieved after a single administration of 277.5 MBq. In rats bearing larger (> or =1 cm(2)) tumors, 40% and 50% cure rates were achieved in the groups that received 1 or 2 277.5 MBq injections of [(177)Lu-DOTA(0),Tyr(3)]octreotate, respectively. After therapy with [(177)Lu-DOTA(0),Tyr(3)]octreotide in rats bearing small tumors, these data were 40% cure after 1 injection with 277.5 MBq and 60% cure after 2 repeated injections. In conclusion, [(177)Lu-DOTA(0),Tyr(3)]octreotate has demonstrated excellent results in radionuclide therapy studies in rats, especially in animals bearing smaller tumors. This candidate molecule shows great promise for radionuclide therapy in patients with sst(2)-expressing tumors.

Somatostatin receptor scintigraphy useful in stage I-II Hodgkin's disease: more extended disease identified

Somatostatin receptor (SS-R) scintigraphy successfully shows primary cancers and metastases in patients with a variety of SS-R-positive tumours. In vitro studies have shown that SS-Rs are present in lymph nodes from patients with Hodgkin's disease (HD). We performed a prospective study in 126 newly diagnosed patients with HD and compared the results of SS-R scintigraphy with conventional staging procedures, i.e. physical examination, computerized tomography (CT) scanning and other imaging techniques. We report positive scintigraphy in all patients. The lesion-related sensitivity was 94% and varied from 98% for supradiaphragmatic lesions to 67% for infradiaphragmatic lesions. In comparison with CT scanning and ultrasonography, SS-R scintigraphy provided superior results for the detection of Hodgkin's localizations above the diaphragm. In the intra-abdominal region, the CT scan was more sensitive than the SS-R scan. A false-positive scan was rarely seen. In stages I and II supradiaphragmatic HD patients, SS-R scintigraphy detected more advanced disease in 18% (15 out of 83) of patients, resulting in an upstaging to stage III or IV, thus directly influencing patient management. Our data would support the validity of SS-R scanning as a powerful imaging technique for the staging of patients with HD.

[(123)I]metaiodobenzylguanidine and [(111)In]octreotide uptake in begnign and malignant pheochromocytomas

Selecting the appropriate approach for resection and follow-up of pheochromocytomas (PCCs) is highly dependent upon reliable localization and exclusion of multifocal, bilateral, or metastatic disease. Metaiodobenzylguanidine (MIBG) scintigraphy was developed for functional localization of catecholamine-secreting tissues. Somatostatin receptor imaging (SRI) has a high sensitivity for localizing head and neck paragangliomas, but studies of intraabdominal PCCs are rare. In this study we review our experience of [(123)I]MIBG and SRI, performed since 1983 and 1989, respectively, in the work-up of primary and recurrent PCCs. Scintigraphic results were correlated with catecholamine secretion, size and site, malignancy, associated tumor syndromes, and morphological features. [(123)I]MIBG scans were performed in a total of 75 patients, in 70 cases before resection of primary PCCs and in 5 cases because of recurrent disease. Ninety-one PCCs were resected. The overall detection rates were 83.3% and 89.8% for PCCs larger than 1.0 cm. Multifocal disease was detected in 4 patients with [(123)I]MIBG. [(123)I]MIBG uptake correlated with greater size of PCC (r = 0.33; P = 0.008) and greater concentration of plasma epinephrine (r = 0.32; P = 0.006). [(123)I]MIBG-negative PCCs (n = 14) had significantly (P = 0.01) smaller diameters than [(123I)]MIBG-positive tumors. Furthermore, [(123)I]MIBG uptake was significantly higher in unilateral (P = 0.02), benign (P = 0.02), sporadic (P = 0.02), intraadrenal (P = 0.02), and capsular invasive (P = 0.03) PCCs than in bilateral, malignant, MEN2A/2B-related, extraadrenal, and noninvasive PCCs, respectively. The detection rate of SRI was only 25% (8 of 32) for primary benign PCCs. In 14 patients metastases occurred, which were effectively visualized with [(123)I]MIBG in 8 of 14 cases. SRI was able to detect metastases in 7 of 8 cases, including 3 [(123)I]MIBG-negative metastatic cases. In addition, [(123)I]MIBG and SRI detected 2 recurrences. In conclusion, [(123)I]MIBG uptake is correlated with the size, epinephrine production, and site of PCCs. Its role in bilateral and MEN2A/2B-related PCCs seems limited. In cases of recurrent elevation of catecholamines, localization of metastases and/or recurrence should be attempted with [(123)I]MIBG scintigraphy. In suspicious metastatic PCCs, SRI might be considered to supplement [(123)I]MIBG scintigraphy.

Somatostatin receptor scintigraphy in the initial staging of low-grade non-Hodgkin's lymphomas

In this prospective study, somatostatin receptor (SS-R) scintigraphy was compared with conventional staging procedures for the initial staging of patients with low-grade non-Hodgkin's lymphoma (NHL).

METHODS

Fifty consecutive untreated patients with low-grade NHL underwent SS-R scintigraphy as part of their initial staging. Planar images were obtained 24 and 48 h after intravenous injection of 220 MBq (111)In-pentetreotide. SPECT images of the upper abdomen were obtained from all patients. SS-R scans were evaluated blindly without knowledge of the results of the conventional staging methods. SS-R scintigraphy findings were compared with the results of physical and radiologic examinations.

RESULTS

SS-R scintigraphy findings were positive in 42 of 50 patients (84%). In 10 patients (20%), the SS-R scan revealed new lesions that had not been revealed by conventional staging procedures. These 10 patients were all upgraded to a higher stage. Consequently, the treatment plan would have been altered in 5 patients (10%). However, in 19 patients (38%), lesions apparent after conventional staging methods were missed by SS-R scintigraphy. The sensitivity of SS-R scintigraphy varied from 62% for supradiaphragmatic lesions to 44% for infradiaphragmatic lesions. The specificity of SS-R scintigraphy was high (98%-100%). In comparison with CT scanning and sonography, SS-R scintigraphy is inferior for the visualization of NHL lesions in the thorax and abdomen.

CONCLUSION

Although SS-R scintigraphy findings are positive in a large proportion of patients with low-grade NHL, in most patients only part of the lesions can be visualized. Because of the limited sensitivity, we recommend SS-R scintigraphy for initial staging of patients with low-grade NHL only in selected conditions and not for the general work-up.

Somatostatin receptor imaging, therapy and new strategies in patients with neuroendocrine tumours

BACKGROUND

Somatostatin receptors have been found on a variety of neuroendocrine tumours, such as carcinoids and paragangliomas, as well as on most pancreatic endocrine and breast tumours. Somatostatin receptor scintigraphy with a radionuclide-labelled somatostatin analogue, [111Indium- diethylenetriaminopenta-acetic acid]octreotide, is a sensitive and specific technique for visualizing in vivo the presence of somatostatin receptors on various tumours.

METHODS

Material was identified from previous review articles, references cited in original papers and a Medline search of the literature. Additional material was obtained from recently published abstracts of meetings.

RESULTS AND CONCLUSION

Somatostatin receptor imaging of neuroendocrine tumours is essential in the diagnostic evaluation of most of these tumours. The expression of somatostatin receptors in vivo not only predicts the outcome of somatostatin analogue treatment but also opens the possibility of new therapeutic strategies. Because better information about spread of the disease can be obtained, more justifiable options for therapy can be proposed.

Controlled introduction of the sentinel node biopsy in breast cancer in a multi-centre setting: the role of a coordinator for quality control

AIMS

It is proposed that sentinel node biopsy should replace axillary lymph-node dissection. We analysed the role of a coordinator in the introduction of the sentinel node biopsy in breast cancer in a multi-centre setting to assure standardization and quality control.

METHODS

We included 232 operable breast cancer patients. Part of the procedure was an ultrasound examination of the axilla with fine needle aspiration cytology. The sentinel node was identified with 99m-Technetium and Patent Blue.

RESULTS

The results of the procedure, sensitivity and false negativity, were the same for the three participating hospitals. We think this is mostly due to the coordinator who supplied information about the technique, pitfalls and results to all teams.

CONCLUSIONS

Our experience regarding the organization aspects of introducing the sentinel node procedure in a multi-centre setting now serves as a model in organizing its application in a much wider number of hospitals.

Peptide receptor imaging and therapy

This article reviews the results of somatostatin receptor imaging (SRI) in patients with somatostatin receptor-positive neuroendocrine tumors, such as pituitary tumors, endocrine pancreatic tumors, carcinoids, gastrinomas, and paragangliomas, or other diseases in which somatostatin receptors may also be expressed, like sarcoidosis and autoimmune diseases. [(111)In-DTPA0]octreotide is a radiopharmaceutical that has great potential for helping visualize whether somatostatin receptor-positive tumors have recurred. The overall sensitivity of SRI to localize neuroendocrine tumors is high. In several neuroendocrine tumor types, inclusion of SRI in the localization or staging procedure may be very rewarding in terms of cost effectiveness, patient management, or quality of life. The value of SRI in patients with other tumors, such as breast cancer or malignant lymphomas, or in patients with granulomatous diseases has to be established. The application of radiolabeled peptides may be clinically useful in another way: after the injection of [(111)In-DTPA0]octreotide, surgeons can detect tumor localizations by a probe that is used during the operation. This may be of particular value if small tumors with a high receptor density are present (e.g., gastrinomas). As the success of peptide receptor scintigraphy for tumor visualization became clear, the next logical step was to try to label these peptides with radionuclides emitting alpha or beta particles, or Auger or conversion electrons, and to perform radiotherapy with these radiolabeled peptides. The results of the described studies with 90Y- and (111)In-labeled octreotide show that peptide receptor radionuclide therapy using radionuclides with appropriate particle ranges may become a new treatment modality. One might consider the use of radiolabeled somatostatin analogs first in an adjuvant setting after surgery of somatostatin receptor-positive tumors to eradicate occult metastases and second for cancer treatment at a later stage.

Bone mineral density, body composition, and height in long-term survivors of acute lymphoblastic leukemia in childhood

BACKGROUND

Childhood leukemia has increasing numbers of survivors, so more emphasis is being placed on long-term effects. The ALL-6 protocol of the Dutch Childhood Leukemia Study Group involved high-dose dexamethasone and methotrexate and no cranial irradiation. Therefore, we studied the long-term effects on bone mineral density (BMD), body composition, and growth in survivors of non-high-risk ALL treated with the ALL-6 protocol.

PROCEDURE

Twenty-three subjects (12.2-25.4 years) participated in this cross-sectional study. Mean follow-up was 9.6 years (range 7.9-11.4 years). BMD of lumbar spine (LS) and total body (TB) and body composition were measured by dual energy X-ray absorptiometry; results are expressed as standard deviation scores (SDS). Bone mineral apparent density (BMAD(LS)) was calculated to correct for bone size. A questionnaire was administered to determine physical activity, calcium intake, and medical history.

RESULTS

Mean SDS for BMD(LS), BMD(TB), and BMAD(LS) were normal. None of the subjects had BMD below -2 SDS; one subject had BMAD(LS) below -2 SDS. Mean SDS for lean body mass, percentage fat, and height were not significantly different from zero. Calcium intake correlated positively with BMD. Nine subjects reported traumatic fractures (eight during or shortly after therapy).

CONCLUSIONS

Ten years after ALL-6 treatment, no long-term side effects on height, BMD, or body composition were found in this small group of patients, despite high-dose dexamethasone and methotrexate. This study suggests that ALL treatment without cranial irradiation might not be associated with long-term side effects on growth and BMD.

Cholecystokinin receptor imaging using an octapeptide DTPA-CCK analogue in patients with medullary thyroid carcinoma

Cholecystokinin (CCK)-B receptors have been demonstrated on a high percentage of medullary thyroid carcinomas (MTC) in vitro. After encouraging results both in vitro and in animal studies, we studied the efficacy of an octapeptide [111In-DTPA]-CCK analogue in seven patients with MTC. In four of five patients in whom serum calcitonin levels were monitored, a significant rise was found following the injection, indicating retained biological activity of the radiopeptide. In all patients there was visualization of the CCK-B receptor-positive stomach. In one of two patients with known MTC lesions, some of the lesions were visualized; in addition some lesions were visualized in one of the five other patients who had elevated serum tumour markers but negative localizing studies. Radioactivity in the presumed tumour sites was still present at 48 h p.i. The uptake in the presumed tumour sites and stomach was low. Background radioactivity dropped rapidly owing to urinary excretion. After 1 h, breakdown products of the labelled analogue predominated both in urine and in serum, and virtually no intact peptide was present.

IN CONCLUSION

(1) the CCK-B receptor-positive gastric mucosa and presumed MTC lesions could be visualized in patients using an octapeptide [111In-DTPA]-CCK analogue that is probably internalized, proving the feasibility of CCK-B receptor imaging in vivo; (2) there was a relatively low uptake of the CCK analogue in the strongly CCK receptor positive stomach, and rapid degradation of the peptide in serum.

Accuracy of exercise stress technetium 99m sestamibi SPECT imaging in the evaluation of the extent and location of coronary artery disease in patients with an earlier myocardial infarction

BACKGROUND

This study assessed the accuracy of exercise methoxy isobutyl isonitrile (MIBI) single photon emission computed tomography (SPECT) in the evaluation of the extent of coronary artery disease (CAD) in patients with an earlier myocardial infarction.

METHODS AND RESULTS

We studied 135 patients (mean age, 57+/-10 years; 115 men) at a mean of 4.1 years (median, 1 year) after myocardial infarction with symptom-limited bicycle exercise stress and rest MIBI SPECT imaging. Coronary angiography was performed within 3 months. Significant CAD was defined as a stenosis of 50% or larger in luminal diameter in 1 or more major coronary arteries. Myocardial perfusion defects (fixed, reversible, or both) were detected in 107 of the 113 patients with significant CAD and in 10 of the 22 patients without significant CAD (sensitivity, 95%; CI, 91 to 99; specificity, 55%; CI, 46 to 63, and accuracy, 88%; CI, 82 to 94). The specificity rate increased to 73% (CI, 65 to 80) by using only reversible perfusion defects as a means of predicting CAD. Reversible perfusion abnormalities were more frequent in patients with multivessel CAD than in patients with single-vessel CAD (51 of 64 [80%] vs. 27 of 49 [55%], P<.01). Myocardial perfusion abnormalities in 2 vascular regions, which is suggestive of multivessel CAD, were detected in 35 of the 64 patients with and in 9 of the 71 patients without multivessel CAD (sensitivity for detecting CAD in more than one vascular region, 55%; CI, 46 to 63, specificity, 87%; CI, 81 to 93, and accuracy, 72%; CI, 64 to 80). The sensitivity rates for the diagnosis of left anterior descending coronary artery, left circumflex, and right coronary artery based on any defect were 80%, 70%, and 63%, respectively. The corresponding specificity rates were 70%, 76%, and 73%, respectively.

CONCLUSIONS

Exercise MIBI SPECT imaging is an accurate method for the diagnosis and localization of CAD in patients with an earlier myocardial infarction. The technique provides a high specificity and moderate sensitivity for the diagnosis of multivessel CAD on the basis of myocardial perfusion abnormalities in more than 1 vascular region.

Evaluation of a radiolabelled cyclic DTPA-RGD analogue for tumour imaging and radionuclide therapy

Tumours depend on sufficient blood supply for their growth. They are able to promote new blood vessel formation (neoangiogenesis) via angiogenic factors. Inhibition of this process results in tumour involution or necrosis. RGD (Arg-Gly-Asp) peptides are described to antagonise neoangiogenesis, e.g., by binding to alpha(v)beta(3) receptors on blood vessels. In order to visualise neoangiogenesis in tumours in vitro and in vivo, we introduced and tested an RGD analogue [c(Arg-Gly-Asp-D-Tyr-Lys)], coupled to the chelator diethyleletriamepentaacetic acid (DTPA). This analogue can be radiolabelled with both (111)In and (125)I. In autoradiography and immunohistochemistry studies, the (125)I-labelled analogue appeared to bind specifically and with high affinity to alpha(v)beta(3) receptors on neovascular blood vessel sections of different major human cancers, like prostate and breast cancer, which express these receptors. This radioiodinated radiopharmaceutical also bound to and internalised in human carcinoid Bon cells and rat pancreatic CA20948 tumour cells. Internalisation was receptor-specific and appeared to be time and temperature dependent. In vivo in rats, we investigated administration of different peptide amounts (0.1, 0.5, and 100 microg). The best amount of the radiolabelled analogue to be administered to rats appeared to be 0.1 microg/rat, as uptake decreased with increasing peptide amount. We also found receptor-specific accumulation of the (111)In-labelled analogue in the transplantable pancreatic tumour CA20948. The introduction of the DTPA group in this peptide resulted in renal clearance of the radiopharmaceutical, in contrast to the non-DTPA-conjugated compound that is cleared predominantly via the liver. (111)In emits Auger and conversion electrons besides gamma radiation, therefore, this radiopharmaceutical is suitable not only for tumour scintigraphy but also has potential for radionuclide therapy of major human cancers as well. Moreover, after coupling to the chelator DOTA, the analogue could be radiolabelled in a stable way with beta-emitters, e.g., (90)Y and (177)Lu, enlarging its potential. Int. J. Cancer (Radiat. Oncol. Invest.) 90, 186-198 (2000).

Tc-99m sestamibi before and during treatment in a patient with sarcoidosis and persistent hyperparathyroidism

PURPOSE

Tc-99m sestamibi (MIBI) uptake in pulmonary sarcoidosis has been reported, but it has never been studied before and during treatment with glucocorticoids.

METHODS

The authors performed MIBI scintigraphy and somatostatin receptor scintigraphy in a patient with sarcoidosis of the mediastinum, lungs, and liver and who had persistent hyperparathyroidism after unsuccessful neck exploration.

RESULTS

Somatostatin receptor scintigraphy showed high mediastinal and pulmonary uptake in a pattern characteristic of sarcoidosis. Sustained MIBI uptake occurred in the same, although smaller, region. After the diagnosis was confirmed by liver biopsy, the patient was treated with glucocorticoids. Repeated MIBI scintigraphy showed that the uptake in the mediastinum had clearly decreased.

CONCLUSIONS

This decrease of MIBI uptake in the mediastinal lymph nodes with therapy may imply that MIBI can be used to assess the response to treatment in sarcoidosis. Perhaps a relation exists between MIBI uptake at the moment of diagnosis and prognosis. Further studies in more patients are needed to evaluate the role of MIBI in the management of sarcoidosis.

Accuracy of dobutamine tetrofosmin myocardial perfusion imaging for the noninvasive diagnosis of transplant coronary artery stenosis

BACKGROUND

Exercise stress myocardial perfusion scintigraphy has been used for the diagnosis of transplant coronary artery stenosis (TCAS) in cardiac allograft recipients. However, the role of pharmacologic stress myocardial perfusion imaging has not been evaluated. Aim of the study is to assess the accuracy of dobutamine stress 99m technetium tetrofosmin myocardial perfusion imaging for the diagnosis of TCAS in heart transplant recipients.

PATIENTS AND METHODS

We studied 50 patients (age 56 +/- 8 year, 45 men) at a mean of 6.4 +/- 2.8 years after cardiac transplant with dobutamine (up to 40 ìg/kg/min) stress 99m technetium tetrofosmin SPECT. Resting images were acquired 24 hours after the stress study. Significant TCAS was defined as > or =50% luminal diameter stenosis by coronary angiography.

RESULTS

Significant TCAS was detected in 30 patients (60%). Myocardial perfusion abnormalities (reversible and/or fixed defects) were detected in 27 of the 30 patients with and in 9 of the 20 patients without significant TCAS (sensitivity = 90%, CI 82-98, specificity = 55% CI 41-69, positive predictive value = 75%, CI 63-87, negative predictive value = 79%, CI 67-90 and accuracy = 76%, CI 64-88). Patients with multivessel TCAS had a larger stress perfusion defect score (5.6 +/- 3.1 vs 3.2 +/- 2.4, p < 0.05) compared to patients with single vessel TCAS. Among patients with abnormal perfusion who had no significant TCAS, 2 had lesions <50%, 2 had luminal irregularities and 5 had no abnormalities at angiography. Therefore specificity was 62% (8/13) in patients without any detectable angiographic abnormalities.

CONCLUSIONS

Dobutamine stress tetrofosmin myocardial perfusion imaging is a highly sensitive method for the detection of TCAS in recipients of cardiac allografts. The high negative predictive value of the test indicates that patients who demonstrate normal perfusion by this method may be excluded from further invasive studies.

Safety, hemodynamic profile, and feasibility of dobutamine stress technetium myocardial perfusion single-photon emission CT imaging for evaluation of coronary artery disease in the elderly

OBJECTIVES

Cardiovascular disease is the leading cause of morbidity and mortality in the elderly. The evaluation of coronary artery disease by exercise stress testing is frequently limited by the patient's inability to exercise. Although pharmacologic stress testing with dobutamine is an alternative, the safety of dobutamine myocardial perfusion scintigraphy in the elderly has not been previously studied.

PATIENTS AND METHODS

We studied the safety and feasibility of dobutamine (up to 40 microg/kg/min)-atropine (up to 1 mg) stress myocardial perfusion scintigraphy using technetium single-photon emission CT imaging in 227 patients > or = 70 years old (mean +/- SD age, 75 +/- 4 years). A control group of 227 patients < 70 years old (mean age, 55 +/- 11 years; matched for gender, prevalence of previous infarction, beta-blocker therapy, and severity of resting perfusion abnormalities) was studied to assess age-related differences in the safety and the hemodynamic response. A feasible test was defined as the achievement of the target heart rate and/or an ischemic end point (angina, ST-segment depression, or reversible perfusion abnormalities).

RESULTS

No myocardial infarction or death occurred during the test. The target heart rate was achieved more frequently in the elderly patients (87% vs 79%; p < 0.05). The elderly patients had a higher prevalence of supraventricular tachycardia (7% vs 1%; p < 0.005) and premature ventricular contraction (74% vs 32%; p < 0.005) during the test, as compared to the younger patients. There was a trend to a higher prevalence of ventricular tachycardia (5% vs 2%) and atrial fibrillation (3% vs 0.4%) in the elderly patients. Arrhythmias were terminated spontaneously by termination of dobutamine infusion or by administration of metoprolol. Independent predictors of supraventricular tachyarrhythmias and ventricular tachycardia were older age (p < 0.001; chi(2), 9.8) and myocardial perfusion defect score at rest (p < 0.01; chi(2), 6.8) respectively, by using a multivariate analysis of clinical and stress test variables. Elderly patients had a higher prevalence of systolic BP drop > 20 mm Hg during the test (37% vs 12%; p < 0.05). The test was terminated due to hypotension in 2% of the elderly patients and in 1% of the control group. Age was the most powerful predictor of hypotension (p < 0.005; chi(2), 10.3). The test was considered feasible in 216 elderly patients (95%) and in 209 patients of the control group (92%).

CONCLUSION

Dobutamine-atropine stress myocardial perfusion scintigraphy is a highly feasible method for the evaluation of coronary artery disease in the elderly. Elderly patients have a higher risk for developing hypotension and supraventricular tachyarrhythmias during a dobutamine stress test. However, dobutamine-induced hypotension is often asymptomatic and rarely necessitates the termination of the test.

Changes in renal tri-iodothyronine and thyroxine handling during fasting

OBJECTIVE

Liver handling of thyroid hormones (TH) has been known to alter significantly during fasting. This study investigates whether renal handling of TH is also changed during fasting.

METHODS

We measured urinary excretion rates and clearances of free tri-iodothyronine (T(3)) and free thyroxine (T(4)) in healthy subjects prior to and on the third day of fasting.

RESULTS

During fasting, both mean T(3) and T(4) urinary excretion decreased significantly to a mean value of 42% of control. Also, total and free (F) serum T(3) concentrations declined significantly, but serum T(4) did not change. Both FT(3) and FT(4) clearance decreased significantly during fasting (62% and 42% of control). The fasting-induced decrease in uric acid clearance correlated well with the decrease in FT(3) clearance (r=0.94; P<0.001). Serum concentrations of non-esterified fatty acids (NEFA) were significantly elevated during fasting.

CONCLUSIONS

The findings cannot be fully explained by the fasting-induced decrease in serum T(3), and are in accordance with inhibition of uptake of T(3) and T(4) at the basolateral membrane of the tubular cell. This inhibition may be caused by a decreased energy state of the tubular cell and by other factors such as ketoacidosis and/or increased NEFA concentrations during fasting.

The role of radioactive somatostatin and its analogues in the control of tumor growth

Peptide receptor scintigraphy with the radioactive somatostatin analogue [111In-DTPA-D-Phe1]octreotide is a sensitive and specific technique to show in vivo the presence and abundance of somatostatin receptors on various tumors. With this technique primary tumors and metastases of neuroendocrine cancers as well as of many other cancer types can be localized. This technique is currently used to assess the possibility of peptide receptor radionuclide therapy with repeated administration of high doses of [111In-DTPA-D-Phe1]octreotide. 111In emits Auger and conversion electrons, having a tissue penetration of 0.02-10 microns and 200-500 microns, respectively. Thirty end-stage patients with mostly neuroendocrine progressing tumors were treated with [111In-DTPA-D-Phe1]octreotide, up to a maximal cumulative patient dose of about 74 GBq, in a phase-I trial. There were no major clinical side effects after up to 2 years of treatment, except that in a few patients a transient decline in platelet counts and lymphocyte subsets occurred. Promising beneficial effects on clinical symptoms, hormone production, and tumor proliferation were found. Of the 21 patients who received a cumulative dose of more than 20 GBq, eight showed stabilization of disease and six others a reduction in tumor size. There is a tendency towards better results in patients whose tumors have a higher accumulation of the radioligand. Peptide receptor radionuclide therapy is also feasible with 111In as the radionuclide. Theoretically, depending on the homogeneity of distribution of tumor cells expressing peptide receptors and the size of the tumor, beta-emitting radionuclides, e.g., 90Y, labeled to DOTA-chelated peptides may be more effective than 111In for peptide receptor radionuclide therapy. The first peptide receptor radionuclide therapy trials with [90Y-DOTA-Tyr3]octreotide started recently.

Preclinical and initial clinical evaluation of 111In-labeled nonsulfated CCK8 analog: a peptide for CCK-B receptor-targeted scintigraphy and radionuclide therapy

The presence of cholecystokinin (CCK)-B (gastrin) receptors has been shown in more than 90% of medullary thyroid cancers (MTCs) and in a high percentage of small cell lung cancers, stromal ovarium cancers and several other tumor types.

METHODS

The aim of this study was to evaluate in vitro and in vivo whether 111In-labeled CCK-B receptor-specific CCK8 analog [D-Asp26,Nle28,31]CCK26-33 (D-Asp-Tyr-Nle-Gly-Trp-Nle-Asp-Phe-NH2) is suitable for CCK-B receptor scintigraphy based on the finding that unlabeled nonsulfated diethylenetriamine pentaacidic acid [DTPA0]CCK8 and tetraazacyclododecanetetraacetic acid [DOTA0]CCK8 analogs show high and specific binding for CCK-B receptors in human tumors. Fifty percent inhibitory concentrations were in the low nanomolar range.

RESULTS

In vitro, [111In-DOTA0]CCK8 showed specific internalization in CCK-B receptor-positive rat pancreatic tumor cells AR42J. Internalization of the analog appeared to be time and temperature dependent and receptor specific. From the data obtained with [111In-DOTA0]CCK8 and (125I)I-gastrin, the latter being a specific ligand for the CCK-B receptor, the rat pancreatic cell line CA20948 also appeared to be CCK-B receptor positive. This provides an in vitro and in vivo rat tumor model because this cell line can be grown to solid tumors in Lewis rats. In vivo biodistribution experiments in CA20948 tumor-bearing Lewis rats showed rapid clearance of [111In-DOTA0]CCK8, and specific uptake was found in the CCK-B receptor-expressing stomach and tumor. Furthermore, comparing [111In-DOTA0]CCK8 with the radioiodinated nonsulfated CCK10 analog (D-Tyr-Gly-Asp-Tyr-Nle-Gly-Trp-Nle-Asp-Phe-NH2), both ligands having high affinity for the CCK-B receptor, tumor-to-blood ratios were significantly higher for [111In-DOTA0]CCK8 than for 125I-CCK10, analogous to the findings with radioiodinated and 111In-labeled octreotide. The study in humans with [111In-DTPA0]CCK8 showed receptor-specific uptake in the CCK-B receptor-positive stomach and in metastases in the neck region up to 48 h after injection.

CONCLUSION

[111In-DOTA0]CCK8 is most promising for scintigraphy and, after coupling to therapeutic radionuclides, for radionuclide therapy of human CCK-B receptor-positive tumors such as MTC and small cell lung cancer.

Therapy of neuroendocrine tumors with radiolabeled somatostatin-analogues

Peptide receptor scintigraphy with the radioactive somatostatin-analogue [111In-DTPA0]octreotide (DTPA = diethylenetriaminepentaacetic acid) is a sensitive and specific technique to show in vivo the presence and abundance of somatostatin receptors on various tumors. With this technique primary tumors and metastases of neuroendocrine cancers as well as of many other cancer types can be localised. A new application is the use of peptide receptor radionuclide therapy, administrating high doses of 111In- or 90Y-labeled octreotide-analogues. PRECLINICAL: We investigated the radiotherapeutic effect of 90Y- and 111In-labeled [DOTA0,Tyr3]octreotide (DOTA = tetraazacyclododecanetetraacetic acid) or [111In-DTPA0]octreotide in Lewis rats bearing the somatostatin receptor-positive rat pancreatic tumor CA20948 in A) the flank or B) in the liver.

PATIENTS

Thirty end-stage patients with mostly neuroendocrine progressing tumors were treated with [111In-DTPA0]octreotide, up to a maximal cumulative patient dose of about 74 GBq, in a phase 1 trial. PRECLINICAL RESULTS: A) Flank model: at least two 111MBq injections of [111In-DOTA0,Tyr3]octreotide were needed to reach tumor response, in 40% of the animals complete tumor remission was found after a follow-up period of 10 months. One or two injections of [90Y-DOTA0,Tyr3] octreotide yielded transient stable disease. B) Liver model: we found that peptide receptor radionuclide therapy is only effective if somatostatin receptors are present on the tumors, and is therefore receptor-mediated. High radioactive doses of 370 MBq [111In-DTPA0]octreotide or 93 MBq [90Y-DOTA0,Tyr3]octreotide can inhibit the growth of somatostatin receptor-positive metastases.

CLINICAL RESULTS

There were no major clinical side effects after up to 2 years treatment, except that a transient decline in platelet counts and lymphocyte subsets can occur. Promising beneficial effects on clinical symptoms, hormone production and tumor proliferation were found. Of the 21 patients with progressive disease at baseline and who received a cumulative dose of more than 20 GBq [111In-DTPA0]octreotide, 8 patients showed stabilisation of disease and 6 other patients a reduction in size of tumors. There is a tendency towards better results in patients whose tumors have a higher accumulation of the radioligand.

CONCLUSION

Radionuclide therapy with octreotide-derivatives is feasible, both with 111In and 90Y as radionuclides.

Pre-clinical evaluation of [(111)In-DTPA-Pro(1), Tyr(4)]bombesin, a new radioligand for bombesin-receptor scintigraphy

Bombesin (BN) is a 14-amino-acid neuropeptide with a high affinity for the gastrin-releasing peptide receptor. This receptor has been found to be expressed in a variety of tumours, including lung, breast, prostate and pancreas. A newly synthesized BN analogue, [DTPA-Pro(1),Tyr(4)]BN, was shown to be a high-affinity BN-receptor (BNR) agonist, stimulating prolactin secretion from 7315b cells with an IC(50) of 8 nM. The (111)In-labelled analogue was found to bind with high affinity to rat BNR in vitro and in vivo. The radioligand is internalized by BNR-expressing cells, in contrast to DTPA-conjugated BN antagonists. Therefore, we further studied the biodistribution of i.v. injected [(111)In-DTPA-Pro(1),Tyr(4)]BN in rats. High and specific uptake was found in tissues of the gastrointestinal tract, notably pancreas. Uptake of radioactivity was blocked by pre- or co-injection of 100 microgram [Tyr(4)]BN, but not when this was administered 30 min after the radioligand. This suggests BNR-mediated internalization of the radioligand within 30 min. The percentage injected dose (ID) taken up by BNR-positive tissues was a bell-shaped function of the amount (0.01-0.1 microgram) of injected ligand. Next to the pancreas, highest uptake was observed in the kidneys, which was not blocked by excess [Tyr(4)]BN. Dynamic gamma camera studies showed rapid clearance of radioactivity from the blood compartment. Urinary excretion amounted to about 35% ID after 1 hr and to 70% ID after 24 hr, with a total body retention of 10% ID. Specific uptake was found in the BNR-positive CA20948 pancreas tumour and CC531 colon carcinoma in tumour-bearing rats. The CA20948 tumour, inoculated in the hindleg, was also visualized scintigraphically. [(111)In-DTPA-Pro(1), Tyr(4)]BN appears to be a promising radioligand for scintigraphy of BNR-expressing tumours.

Bone mineral density in children with acute lymphoblastic leukaemia

Bone mineral density (BMD) may be negatively affected by the disease or its treatment in patients with acute lymphoblastic leukaemia (ALL). Therefore, we evaluated lumbar spine and total body BMD and bone metabolism in children with ALL at diagnosis, during treatment with chemotherapy and 1 year after completion of treatment. 32 children (21 boys and 11 girls) participated in the study. 14 children started the study at diagnosis and 18 during or after the treatment period. Lumbar spine and total body BMD were measured with dual energy X-ray absorptiometry, and expressed as standard deviation scores (SDS). Blood samples were obtained to assess bone metabolism. 3 of 14 children had low lumbar spine BMD (< -2 S.D.) at diagnosis. All children had normal total body BMD. Markers of bone turnover were depressed. Total body BMD SDS decreased significantly during the first year of treatment (P < 0.001). Lumbar spine BMD SDS did not change significantly. Parameters of bone turnover increased to normal during the treatment period. Parathyroid hormone had increased significantly after 1 year (P < 0.05). Mineral homeostasis was disturbed in some patients during treatment. 4 of 9 patients had low total body BMD and 1 patient low lumbar spine BMD one year after completion of treatment. All patients had normal biochemical results at that time. In conclusion, lumbar spine BMD and bone turnover were decreased in some patients at diagnosis. Total body BMD decreased significantly during treatment and was low in 4 of the 9 patients 1 year after completion of the treatment.

Scintigraphy and radionuclide therapy with [indium-111-labelled-diethyl triamine penta-acetic acid-D-Phe1]-octreotide

Peptide receptor scintigraphy with [111In-DTPA-D-Phe1]-octreotide is a sensitive and specific technique to show in vivo the presence and abundance of somatostatin receptors on various tumours. With this technique primary tumours and metastases of neuroendocrine cancers as well as of many other cancer types can be localised. This technique is currently used to assess the possibility of peptide receptor radionuclide therapy with repeated administrations of high doses of [111In-DTPA-D-Phe1]-octreotide. 111In emits Auger and conversion electrons having a tissue penetration of 0.02 to 10 microns and 200 to 500 microns, respectively. Twenty end-stage patients, mostly with neuroendocrine progressing tumours, were treated with [111In-DTPA-D-Phe1]-octreotide, up to a maximal cumulative patient dose of about 74 GBq, in a phase I trial. Results showed there were no major clinical side-effects after up to 2 years treatment, except that in a few patients a transient decline in platelet counts and lymphocyte subsets occurred. Promising beneficial effects on clinical symptoms, hormone production and tumour proliferation were found. Of the 16 patients who received a cumulative dose of more than 20 GBq, 5 patients showed stabilisation of disease and 5 other patients a reduction in size of tumours. There is a tendency towards better results in patients whose tumours have a higher accumulation of the radioligand. In conclusion, peptide receptor radionuclide therapy is feasible, also with 111In as radionuclide. Theoretically, depending on the homogeneity of distribution of tumour cells expressing peptide receptors, beta-emitting radionuclides, e.g. 90Y, labelled to DOTA-chelated peptides may be more effective than 111In for peptide receptor radionuclide therapy. The first peptide receptor radionuclide therapy trials with [90Y-DOTA-Tyr3]-octreotide started recently.