[en] A practical guide has been composed for all persons involved in the preparation and use of radiopharmaceuticals on methods used in quality assurance and their applications. These methods include the calibration of ionization chamber assay calibrators, the determination of radionuclide purity, radiochemical purity and chemical purity, particle size analysis and the measurement of pH. Quality assurance procedures are described for products not described in Compendial Monographs, or where the monograph exists, additional useful information is provided; such radiopharmaceuticals include technetium, indium-labelled and iodine-labelled products. (U.K.)

[en] Full text: The psychomotor stimulant methylphenidate (MP) and several derivatives have demonstrated high affinity binding to a site on the dopamine transporter (DAT). Here we report the pharmacological evaluation of 3-[¹²³I]iodomethylphenidate (^l23MP) and 3-[⁷⁶Br]bromomethyl phenidate (⁷⁶BrMP) as potential SPET and PET tracers for the study of the DAT. Racemic ¹²³IIMP and ⁷⁶BrMP were synthesized from the corresponding 3-tributylstannyl methylphenidate using Na¹²³I or NH₄⁷⁶Br in the presence of chloramine-T. In vivo biodistribution of the active enantiomers of ¹²³IMP in rats indicated a striatum (STR) to cerebellum (CB) ratio of 2.4 at 30 min p.i. Pretreatment of the rats with MP, WIN 35,428 and GBR 12909 reduced the STR/CB ratio to unity. Similarly, in vivo biodistribution of ⁷⁶BrMP in rats also indicated high uptake in the striatum with a STR/CB ratio of 5.5 at 120 min p.i. Administration of ¹²³IMP and ⁷⁶BrMP in primates and examination by SPET and PET indicated a high accumulation of radioactivity in the striatum with rapid washout in other non-dopaminergic tissue. These results indicate that the active enantiomers of ¹²³IMP and of ⁷⁶BrMP have the potential for further development as SPET and PET tracers for the study of neurodegenerative diseases such as Parkinson's disease

[en] Full text: Osteopenia/osteoporosis and fractures have been shown to occur with anorexia nervosa (AN). This study evaluated adolescent females diagnosed with AN less than 12 months previously to determine the presence of any significant bone mass reduction at this early stage of diagnosis and to evaluate the correlation between total body (TB) and lumbar spine (LS) bone mineral densities (BMD) and bone mineral content (BMC), and nutritional indices (body weight, body mass index (BMI), lean mass, fat mass and percentage fat). The subjects were 22 adolescent females aged 12-17 years (mean= 14.3 years) diagnosed with AN less than 12 months earlier (range 2.5-11 months; mean = 6.7 months). They had bone density measurements of the TB and LS using a Lunar DPX-L densitometer. Comparison was made with values of age-matched controls in the Lunar normative database. Although there was a tendency towards low TB and LS bone mass, these changes were not statistically significant. Bivariate analyses showed significant correlation between TB BMD and lean mass (P < 0.001) and weight (P < 0.001) and between TB BMC and lean mass (P < 0.001) and weight (P < 0.01). There was similar significant correlation between LS BMD and lean mass (P < 0.01) and weight (P<0.01), and between LS BMC and lean mass (P < 0.01) and weight (P < 0.01). With stepwise regression analysis, only lean mass remained significantly correlated with TB BMD and BMC and LS BMD and BMC. There was no longer any significant correlation with weight. In this study, the weight percentile was found to be correlated highly with the LS BMD Z-score (P < 0.01). Therefore, during adolescence, the lean mass in particular, but also body weight, are good indicators of bone densities. Adolescent females do not appear to show bone mass reduction in the early stages of diagnosis of anorexia nervosa. This suggests early intervention may preserve bone gain and attainment of normal peak bone mass

[en] Full text: Autologous ⁹⁹Tc^m-leukocyte scanning has been performed in patients for the detection of inflammation, osteomyelitis, query of abscess, infection, fever of unknown origin and cellulitis using gamma camera imaging, in our department at The Royal Melbourne Hospital. Our aim was to demonstrate the effectiveness of the test for an accurate and early diagnosis of the above mentioned diseases. 316 patients were studied (1988-98). Autologous leukocytes were radiolabelled using the manufacturer's instructions (Radpharm). Labelling efficiency >95%. Scans were performed 0.5 and 2-3 h after intravenous administration. The sensitivity of the scan for osteomyelitis was 92%, for abscess 80% and for inflammation 89%. The specificity for osteomyelitis was 90%, for abscess 86% and for inflammation 100%. Results relating to cellulitis and fever of unknown origin have yet to be collated and these will be presented at the conference. In conclusion, the availability, low cost and minimally invasive method of labelling, make the use of ⁹⁹Tc^m-colloid-labelled autologous leukocytes easy and interesting for scintigraphy, especially because no cell separation is involved. During the period of 10 years, no patients suffered any major or minor side-effects from this agent

[en] Full text: Accurate attenuation correction in the thorax mandates transmission measurement. Fan beam based transmission systems are most common on triple-headed gamma cameras due to geometric restrictions. However, the reduced field of view of a fan beam geometry can result in truncation of transmission data in at least some projections. Truncation produces a hot rim artefact in the reconstructed attenuation coefficient maps, decreasing the accuracy of attenuation correction. Four methods for extrapolation of truncated projections were implemented and compared: (1) a second-order polynomial function using a patient edge constraint; (2) a second-order polynomial using patient edge constraint and total from the least truncated projection; (3) an ellipsoid function using a patient edge constraint only; and (4) an ellipsoid using patient edge constraint and μ total from the least truncated projection. Truncation-free transmission data were acquired of a human thorax phantom (Data Spectrum) using a PET scanner with rotating rod sources. From the reconstructed μ maps, SPET emission data and truncated transmission data were simulated. SPET data that were processed with the truncated and the truncation-corrected μ maps were compared with SPET data reconstructed with the non-truncated μ maps. The effect of truncation and truncation-corrected transmission data on transmission-dependent scatter correction (TDSC) was also investigated. In the heart, truncation introduced an error of 7.9% into the SPET data when compared to the non-truncated data, which was reduced to 3.1%, 6.2%, 4.6% and 4.8% for methods 1-4 respectively. No significant difference (P > 0.5) in accuracy between the four methods tested was observed

[en] Full text: Morphometric X-ray absorptiometry (MXA) using DXA is potentially a useful clinical tool which may provide additional vertebral fracture information with low radiation exposure. While morphometric analysis is semi-automated, operator intervention is crucial for the accurate positioning of the six data points quantifying the vertebral heights at the anterior, middle and posterior positions. Our study evaluated intra-operator reproducibility of MXA in an elderly patient population and assessed the effect of training and experience on vertebral height precision. Ten patients, with a mean lumbar T score of - 2.07, were studied. Images were processed by a trained operator who had initially only limited morphometric experience. The analysis of the data files were repeated at 2 and 6 weeks, during which time the operator had obtained further experience and training. The intra-operator precision of vertebral height measurements was calculated using the three separate combinations of paired analyses, and expressed as the coefficient of variation. This study confirms the importance of adequate training and attention to detail in MXA analysis. The data indicate that the precision of MXA is adequate for its use in the diagnosis of vertebral fractures, based on a 20% deformity criteria. Use of MXA for monitoring would require approximately an 8% change in vertebral heights to achieve statistical significance

[en] Full text: Measurement of right ventricular (RV) ejection fraction (EF) can provide important clinical information but is difficult to obtain. Although potentially accurate, first-pass imaging is technically difficult. More usually, RVEF is estimated from planar equilibrium gated heart pool scans (GHPS). These EFs are known to be highly unreliable because of substantial overlap between the RV and the right atrium. We have developed an alternative means for measuring RVEF from equilibrium GHPS, using SPET instead of planar studies. Gated SPET images were acquired (16 bins, 180 deg rotation, 64 stops) and reconstructed into short-axis views. A single region of interest (ROI) was drawn to exclude the left ventricle from the short-axis slices, which were then reprojected to produce horizontal long-axis images. A ROI was drawn around the RV on the end diastolic (ED) long-axis image. Time-activity curves (TACs) were generated from successive rows of pixels in the ED ROI, starting at the basal end. Each TAC was checked for the presence of increased activity at end systole (ES). When two consecutive TACs showed no sign of increased activity at ES, that row was considered to mark the valve plane. Another ROI was then drawn on the ES image and EF was calculated as usual. A group of 18 patients were injected with 900 MBq of ⁹⁹Tc^m and both planar (45 deg LAO, 32 bins) and SPET GHPS were acquired. SPET EFs were easily generated and reasonably consistent (mean standard deviation was ± 5, over 6 repeats). RVEFs from the two techniques show a broad general agreement (slope = 0.5, CC = 0.5). The next step is to compare SPET RVEF with a more accurate technique, such as first-pass, and with clinical outcome

[en] Full text: Interesting images and cases are collected and collated by most nuclear medicine practitioners throughout the world. Changing imaging technology has altered the way in which images may be presented and are reported, with less reliance on 'hard copy' for both reporting and archiving purposes. Digital image generation and storage is rapidly replacing film in both radiological and nuclear medicine practice. A personal computer database based interesting case filing system is described and demonstrated. The digital image storage format allows instant access to both case information (e.g. history and examination, scan report or teaching point) and the relevant images. The database design allows rapid selection of cases and images appropriate to a particular diagnosis, scan type, age or other search criteria. Correlative X-ray, CT, MRI and ultrasound images can also be stored and accessed. The application is in use at The New Children's Hospital as an aid to postgraduate medical education, with new cases being regularly added to the database

[en] Full text: A Design Guideline for ¹³¹I Therapy Facilities (1996) has been developed for the NSW Hospital and University Radiation Safety Officers Group (HURSOG) with recommendations on isolation rooms and delay tanks for storing waste water from the patient toilets. Shielding design for an isolation room is based on a methodology widely used in radiology and radiotherapy. The transmission factor (K) to achieve a dose limit of 20 μSv per week beyond a barrier is calculated for a specified number of ¹³¹I patients per week, average administered activity, and distance (source to recipient on further side of barrier). Default values are recommended for the workload, ¹³¹I dose rate and occupancy factors in the surrounding areas if not known. From the calculated value of K, the barrier thickness in lead or masonry can be obtained from tabulated attenuation data. Delay tanks are designed as a pair, alternately filling and holding waste water until the ¹³¹I activity discharged to the sewer complies with a limit of 20 ALI (i.e. 18 MBq) per week recommended by the National Health and Medical Research Council and acceptable to local water authorities. The Guideline has been used to design shielding for two isolation beds which were relocated to a ward with plasterboard walls. The two nearest adjacent beds were at a distance of 3.5 m. Due to space constraints, lead panels up to 25 mm thick were used for shielding rather than 30 cm thick concrete walls. A 14-week radiation survey of surrounding areas with TLD dosimeters during treatment of 33 patients per room, with an average administered activity of 5.1 GBq, showed doses at the four adjacent beds were below the design limit of 80 μSv per week for an occupancy factor of 0.25 conservatively based on length-of-stay bed data for the ward. Delay tanks installed at another hospital and sized according to the Guideline at 7 m³ per bed fill to 70-80% of capacity during a 3-month fill/3-month decay cycle

[en] Full text: A male patient aged 27 years was injected with 1000 MBq of ⁹⁹Tc^m-MDP. The patient was an active man indulging in contact sport. He presented with lower back and pelvic pain. Spot pictures were made of the pelvis, lumbar spine and femurs. Unexpected active radionuclide uptake in the muscles was seen. In the delayed static images, there was focal accumulation of tracer uptake in the muscles overlying the mid-shaft of the left femur consistent with myositis ossificans. Myositis ossificans is a benign ossifying process that is generally solitary and well circumscribed. It is most commonly found in the muscles but it may occur in other connective tissues, especially tendons and subcutaneous fat. This was presumably associated with chronic muscular injuries contracted during sports activity