[en] Technetium-99m-HM-PAO [(^99mTc]HM-PAO) leukocyte and indium-111-oxine (111In-oxine) leukocyte scanning were carried out simultaneously in 41 patients at 4 hr and 24 hr after reinjection to determine whether the 4-hr ^99mTc scan could replace the 24-hr ¹¹¹In scan for detecting intraabdominal sepsis. Abdominal infection was confirmed in 12 cases. The 4-hr ⁹⁹Tc-leukocyte scan, the 4-hr ¹¹¹In-leukocyte scan, and the 24-hr ¹¹¹In-leukocyte scan yielded a sensitivity of 100%, 67%, and 100%, respectively, and a specificity of 62%, 90%, and 86%, respectively. The 24-hr ^99mTc-leukocyte scan also produced a sensitivity of 100%, but it was falsely positive in all 29 cases without infection due to physiologic bowel uptake. False-positive 4-hr ^99mTc-leukocyte scans were also produced by physiologic bowel uptake in seven cases all of whom had true-negative 4-hr and 24-hr ¹¹¹In-leukocyte scans. Because of the high incidence of false-positive 4-hr [^99mTc]HM-PAO leukocyte scans, it was concluded that they could not replace 24-hr ¹¹¹In-leukocyte scans for detecting intraabdominal sepsis, and that serial ^99mTc leukocyte scans starting earlier than 4 hr after reinjection must be evaluated

[en] This study was designed to examine the possible use of ¹²³I-labelled methylene blue as a parathyroid imaging agent. Five patients were studied, all of whom had parathyroid adenomas which were successfully localized preoperatively with ²⁰¹Tl and ⁹⁹Tc^m-sestamibi, and which were subsequently proven at surgery. The ¹²³I-labelled methylene blue localized only one of these adenomas, was negative in two and had equivocal uptake in the remaining two patients. It is therefore concluded that compared to other radionuclide methods for localizing parathyroid adenomas this agent is unsatisfactory. (author)

[en] Recommendations for restricting the exposure to radiation of members of the public coming into contact with thyrotoxic patients treated with ¹³¹I are currently based on the activity retained by the patient, and not on the doses likely to be received by such individuals. In order to examine whether these current recommendations restrict these doses to less than the current annual limit of 5 mSv, and to identify the implications of a reduction in this limit to 1 mSv, measurements were made of the dose rates at distances of 0.1, 0.5 and 1.0 m from 60 patients just before they left the nuclear medicine department. These measurements were repeated 1, 3, 6, 8 and 10 days after administration for 30 patients, and the radioactivity in samples of saliva taken on each of these days and secreted in sweat over the first 24 h were also measured. Doses were estimated for administered activities of approximately 200-600 MBq, assuming appropriate values for the times and distances spent near other individuals while travelling, at work, at home and near to young children considered in three age groups. Periods of restriction were derived which would reduce these doses to 5 or 1 mSv. (Author)

[en] Short communication

[en] A modified chloramine-T method was used to label a pharmaceutical form of salmon calcitonin (SCT) with iodine-123. Labelling can be performed within 5 min including purification, resulting in >95% radiochemical purity and 70% yield. Digestion analysis shows labelling with two iodine atoms on the tyrosine residue. A Chinese hamster ovary cell-based assay showed that the receptor binding and activation were not impaired by the labelling. Biodistribution in mice was similar to that of commercially available mono-iodinated ¹²⁵I-labelled SCT, kidney being the principal target organ. Evaluation in three patients previously diagnosed as having Paget's disease (injected with 37 MBq [¹²³I]diiodotyrosyl²²-SCT, containing less than 4 IU hormone, imaged dynamically up to 0.5 h and at intervals up to 24 h) shows early uptake in liver, kidney and sites of known Paget's disease but not in normal bone, and later uptake in thyroid and stomach. Blood clearance was fitted to a biexponential with half-lives of 3.4-7.4 min and 3-34 h. Radiation dosimetry was estimated using MIRDOSE 3. The highest doses (mean mGy/MBq) were to thyroid (6.8 x 10^-1) and kidney (6.0 x 10^-2), with a whole-body dose 3.0 x 10^-2. High performance liquid chromatography analysis revealed that urinary radioactivity was mostly in the form of iodide and diiodotyrosine within minutes of injection, indicating rapid in vivo breakdown.(orig. /MG) (orig.)

[en] Rhenium-188 dimercaptosuccinic acid complex [¹⁸⁸Re(V)DMSA], a potential therapeutic analogue of the tumour imaging agent ^99mTc(V)DMSA, is selectively taken up in bone metastases in patients with prostate cancer. It would be helpful in planning palliative radionuclide therapy if ^99mTc(V)DMSA could be used to predict tumour and kidney retention of ¹⁸⁸Re(V)DMSA. The aim of this study was to determine the correlation between tumour-to-normal tissue ratios and kidney-to-soft tissue ratios of ^99mTc(V)DMSA and ¹⁸⁸Re(V)DMSA. This would determine whether a scan with ^99mTc(V)DMSA, could be used to identify patients for whom ¹⁸⁸Re(V)DMSA treatment would be contra-indicated, and enable prediction of relative kidney and tumour radiation absorbed dose in ¹⁸⁸Re(V)DMSA treatment. Ten patients with prostate carcinoma were recruited following observation of disseminated bone metastases on a recent ^99mTc-hydroxydiphosphonate bone scan. Whole-body planar scans were obtained at ca. 4 h and 24 h after hydration and injection of 600 MBq ^99mTc(V)DMSA, and a week later, at similar times after hydration and injection of 370 MBq ¹⁸⁸Re(V)DMSA. A triple-energy window (TEW) scatter correction was applied to the ¹⁸⁸Re scans. Counts per pixel were determined in regions of interest drawn over metastatic sites, kidneys and normal soft tissue. Tumour-to-soft tissue ratios were significantly lower (by a factor of approximately 0.8 after the TEW was applied) on ¹⁸⁸Re scans than on ^99mTc scans, but the two were highly linearly correlated both in all individual patients and in tumours pooled from all patients together both at 4 h and at 24 h. Kidney-to-soft tissue ratios were similarly correlated and were lower for ¹⁸⁸Re than for ^99mTc by a similar factor. Both tumour- and kidney-to-soft tissue ratios increased between 4 and 24 h but the latter increased more. In conclusion, only minor differences were seen between ^99mTc and ¹⁸⁸Re scans, and kidney-to-background ratios on ¹⁸⁸Re scans were not higher than on ^99mTc scans. These differences are insufficient to infer that they are due to a real difference in biodistribution, and they may be due only to different physical imaging characteristics. Thus ^99mTc(V)DMSA scans are predictive of ¹⁸⁸Re(V)DMSA biodistribution and could be used to estimate tumour and renal dosimetry and assess suitability of patients for ¹⁸⁸Re(V)DMSA treatment. (orig.)

[en] The management of 38 consecutive patients with differentiated thyroid carcinoma in the period 1991-1996, who each received at least one therapy dose of iodine-131, was reviewed, looking in particular at those in whom anterior mediastinal uptake was demonstrated on scans taken 3 and 7 days post-therapy. Such activity was noted in ten patients. On the basis of clinical follow-up, thyroglobulin measurement and radiological and other scintigraphic imaging, in nine of the ten patients the anterior mediastinal activity was attributed to physiological thymic uptake. Of those nine, all were under 50 years of age; seven were considered disease free, one had residual disease in the neck and one had distant metastases. Physiological uptake by the thymus was more prominent on the 7-day scans and in patients with low tumour volumes. For appropriate patient management it is essential to recognise that physiological uptake of ¹³¹I by the thymus in patients under 50 years of age is a potential cause of false-positive therapy scans. (orig.)

[en] A patient with recurrent medullary thyroid cancer in the neck in whom previous surgery for recurrence had been undertaken with only partial success had the diseased tissue localized preoperatively by indium-111 pentetreotide. Scanning with technetium-99m V dimercaptosuccinic acid and iodine-123 metaiodobenzylguanidine failed to localize the tumor. Utilization of a nuclear surgical probe after preoperative ¹¹¹In pentetreotide allowed accurate surgical localization of the tumour tissue. (orig.)

[en] The aim of this study was to develop the kit-based synthesis of the agent on a therapeutic scale, to assess its stability in vivo, and to obtain preliminary biodistribution and dosimetry estimates, prior to evaluation of its potential as a targeted radiotherapy agent. The organ distribution of ¹⁸⁸Re in mice was determined 2 h after injection of 3 MBq ¹⁸⁸Re(V)DMSA prepared from eluate from a ¹⁸⁸W/¹⁸⁸Re generator. Three patients with cancer of the prostate and three with cancer of the bronchus, all with bone metastases, were given 370 MBq ¹⁸⁸Re(V)DMSA and imaged at 3 h and 24 h using the 155-keV γ-photon (15%). Blood and urine samples were collected to determine clearance and to analyse the speciation of ¹⁸⁸Re. Organ residence times were estimated from the scans, and used to estimate radiation doses using MIRDOSE 3. In mice, ¹⁸⁸Re(V)DMSA was selective for bone and kidney. In patients, it showed selectivity for bone metastases (particularly those from prostate carcinoma) and kidney, but uptake in normal bone was not significantly greater than in surrounding soft tissues. Of the normal tissues the kidneys received the highest radiation dose (0.5-1.3 mGy/MBq). The images were strongly reminiscent of ^99mTc(V)DMSA scans in similar patients. High-performance liquid chromatography analysis of blood and urine showed no evidence of ¹⁸⁸Re in any chemical form other than ¹⁸⁸Re(V)DMSA up to 24 h. In conclusion, ¹⁸⁸Re(V)DMSA and its ¹⁸⁶Re analogue warrant further clinical assessment as generator/kit-derived agents for treatment of painful bone metastases. These agents should also be assessed in medullary thyroid carcinoma and other soft tissue tumours which have been shown to accumulate ^99mTc(V)DMSA.(orig./MG) (orig.)

[en] Patients who receive radioiodine (iodine-131) treatment for hyperthyroidism (195-800 MBq) emit radiation and represent a potential hazard to other individuals. Critical groups amongst the public are fellow travellers on the patient's journey home from hospital and members of the patient's family, particularly young children. The dose which members of the public are allowed to receive as a result of a patient's treatment has been reduced in Europe following recently revised recommendations from ICRP. The annual public dose limit is 1 mSv, though adult members of the patient's family are allowed to receive higher doses, with the proviso that a limit of 5 mSv should not be exceeded over 5 years. Unless the doses received during out-patient administration of radioiodine can be demonstrated to comply with these new limits, hospitalisation of patients will be necessary. The radiation doses received by family members (35 adults and 87 children) of patients treated with radioiodine at five UK hospitals were measured using thermoluminescent dosimeters mounted in wrist bands. Families were given advice (according to current practice) from their treatment centre about limiting close contact with the patient for a period of time after treatment. Doses measured over 3-6 weeks were adjusted to give an estimate of values which might have been expected if the dosimeters had been worn indefinitely. Thirty-five passengers accompanying patients home after treatment also recorded the dose received during the journey using electronic (digital) personal dosimeters. For the ''adjusted'' doses to infinity, 97% of adults complied with a 5-mSv dose limit (range:0.2-5.8 mSv) and 89% of children with a 1-mSv limit (range: 0.2-7.2 mSv). However 6 of 17 children aged 3 years or less had an adjusted dose which exceeded this 1 mSv limit. The dose received by adults during travel was small in comparison with the total dose received. The median travel dose was 0.03 mSv for 1 h travel (range: 2 μSv-0.52 mSv for 1 h of travel time). These data suggest that hyperthyroid patients can continue to be treated with radioiodine on an out-patient basis, if given appropriate radiation protection advice. However, particular consideration needs to be given to children aged 3 years or younger. Admission to hospital is not warranted on radiation protection grounds. (orig.)