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Evaluation of severe functional gastrointestinal motility disorders requires an investigation of the entire gastrointestinal tract. This should be possible with a single radionuclide imaging study. The purpose of this study was (1) to define normal values of small-bowel transit in men and women and (2) to assess a possible difference between gender or test meal, since it has been shown that women have slower gastric emptying than men, and gastric emptying of solids is slower than liquids. A standard gastric-emptying test for a solid (technetium-99m sulphur colloid, 230 Kcal) and liquid (indium-111 DTPA water) test meal was performed in 12 healthy male and 12 healthy female volunteers. After 135 min, the volunteer was placed in the supine position for static imaging of the abdomen every 15 min for 6 h. Decay and crossover-corrected geometric mean gastric-emptying data were fit to a modified power exponential function to determine the 10% stomach emptying time for solids and liquids separately. An ROI was drawn around the caecum and ascending colon to determine the arrival time of at least 10% of the solid and liquid test meal. Ten percent small-bowel transit time (10% SBTT) and orocaecal transit time (OCTT) were calculated. The OCTT for males and females, respectively for solids and liquids, are 294.6 +/- 18.8; 301.3 +/- 24.5; 294.6 +/- 18.8 and 301.3 +/- 24.5 min. The 10% SBTT for males and females, respectively for solids and liquids, are 280.3 +/- 18.4; 280.6 +/- 24.0; 288.2 +/- 18.9 and 297.4 +/- 24.4 (mean +/- SEM) min. We observed a simultaneous transfer of solids and liquids from the terminal ileum to caecum (correlation coefficient 0.90). There is no statistically significant difference in SBTT between gender or solids and liquids. In contrast to the gastric-emptying time, the SBTT of solids and liquids were not significantly different nor was a gender difference found. Determination of the OCTT seems to be the simplest and most accurate approach to measure SBTT. Since ileocaecal transfer occurs as a bolus phenomenon, a 111In-labelled test meal can also be used for the determination of colon transit in a single imaging study protocol.

There is increasing evidence of gender-related differences in gastric emptying. The purpose of this study was first, to confirm the difference in gastric emptying for both solid and liquid test meals between healthy men and women, and secondly, to investigate the origin of this difference by studying regional gastric emptying and antral motility. A standard gastric emptying test with additional compartmental (proximal and distal) evaluation and dynamic imaging of the antrum was performed in 20 healthy women studied during the first 10 days of the menstrual cycle, and in 31 healthy age-matched men. In concordance with previous reports, women had a longer half-emptying time for solids as compared to men (86. 2+/-5.1 vs 52.2+/-2.9 min, P<0.05). In our observations this seemed to be related to a significantly prolonged lag phase and a significant decrease in terminal slope. Dynamical antral scintigraphy did not show a significant difference. The distribution of the test meal within the stomach (proximal vs distal) showed more early proximal retention in women as compared to men. The terminal slope of the distal stomach was significantly lower in women. We did not observe a significant difference in gastric emptying of the liquid test meal between men and women. Gastric emptying of solids is significantly slower in healthy women as compared to men. These findings emphasise the importance of using different normal values for clinical and research purposes in gastric emptying scintigraphy in men and women. The difference could not be explained by antral motility alone. Increased proximal retention and a lower terminal emptying rate in women are observations to be further investigated.

Positron emission tomography (PET) with 18F-fluoride was utilized to determine the regional blood flow to the femoral head in early osteonecrosis. Five patients with a history of unilateral hip trauma and a normal contralateral side were selected. Skeletal flow and fluoride uptake in the abnormal and normal hips were compared directly, and the relation between bone blood flow and final outcome, i.e., surgical replacement or conservative treatment, was evaluated. In this pilot study, a flow ratio of at least 2 between the abnormal and normal femoral head was necessary to predict a successful outcome with a conservative regimen. A minimum flow of 0.04 ml/min/ml was measured in one patient whose affected femoral head healed conservatively. Our preliminary study indicates that this type of highly technical investigation appears feasible in clinical practice and permits prediction of the outcome depending upon regional skeletal flow measurements in vivo.

This paper summarizes a communication presented at the Second International Conference of Nuclear Cardiology, held in Cannes on 23-26 April 1995. The general evolution of nuclear medicine in Europe is examined within the context of European Union Directives, and the role of the Union of European Medical Specialists/Section of Nuclear Medicine is discussed. Thereafter consideration is given to the technical aspects of cardiovascular nuclear medicine procedures, and the situation with respect to such procedures in European countries is examined. In most European countries, nuclear medicine is a recognized specialty, while "nuclear cardiology" does not exist in its own right. In general, only nuclear medicine specialists have the responsibility for radionuclide studies, and most cardiovascular studies are performed under the direct responsibility of a licensed nuclear medicine specialist.

Recently, we have shown that tetrapeptides can be efficiently labelled with technetium-99m by direct labelling at alkaline pH. Tetrapeptides can be considered derivatives of mercaptoacetyltriglycine (MAG3) in which the mercaptoacetyl moiety is replaced by an amino acid residue. In view of the interesting biological properties of some C-methyl substituted derivatives of 99mTc-MAG3, we have now synthesised and evaluated the complexes of 99mTc with tetrapeptides containing three glycyl (G) moieties and one D- or L-alanyl (A) moiety. In mice, 99mTc-L-GAGG, 99mTc-D-GGAG and 99mTc-L-GGAG showed a rapid and high renal excretion, comparable to that of 99mTc-MAG3. Renal handling was somewhat reduced for isomers d and l of 99mTc-AGGG and 99mTc-D-GAGG and markedly inferior for 99mTc-L-GGGA and 99mTc-D-GGGA. In the baboon, 99mTc-L-AGGG, 99mTc-D-AGGG and 99mTc-L-GAGG showed a comparable or even higher 1-h plasma clearance than 99mTc-MAG3. 99mTc-D-GAGG, 99mTc-L-GGAG and 99mTc-D-GGAG were characterised by a lower plasma clearance and the clearance of 99mTc-L-GGGA and 99mTc-D-GGGA was remarkably low. The three 99mTc-labelled tetrapeptides with the highest plasma clearance in a baboon were compared with 99mTc-MAG3 in a human volunteer. 99mTc-L-AGGG and 99mTc-L-GAGG had a roughly similar plasma clearance as 99mTc-MAG3. The clearance of 99mTc-D-AGGG was significantly lower and liver uptake was clearly visible with this compound. Left kidney renograms of 99mTc-L-AGGG and 99mTc-D-AGGG indicated moderate kidney accumulation. On the other hand, the renogram obtained after injection of 99mTc-L-GAGG had an excellent shape and the maximum kidney concentration was slightly higher than for 99mTc-MAG3. These results show the importance of the position of the methyl substituent on the 99mTc-tetrapeptide with respect to its biological behaviour.

In patients with chronic coronary artery disease, follow-up measurements of myocardial blood flow, metabolism and function were correlated with histology. In 41 patients with chronic coronary artery disease and a severely stenosed left anterior descending coronary artery, a positron emission tomographic (PET) flow/metabolism study and nuclear angiography were performed immediately before and 3 months after bypass surgery. Biopsies were taken from the left ventricular anterior wall at the time of surgery. Control biopsies were taken from donor hearts for cardiac transplantation and from hearts of patients with a defect of the atrial septum. A significant improvement of flow (P<0.01) and regional contractile function (P<0.01) was observed in the mismatch group. Glucose utilization was significantly lower (P<0.001) as compared to preoperative values. The group with preserved flow and the PET match group revealed no significant changes in flow, metabolism or function. Control biopsies revealed significantly less myolytic cells as compared to biopsies taken from both match and mismatch groups (P<0.01) and less fibrosis as compared to biopsies taken from the match group (P<0.01). Postoperatively, linear relationships were found between flow and both % fibrosis (r = 0.71, P<0.001) and regional anterior ejection fraction (r = 0.7, P<0.001). Only mismatch areas revealed significant recovery of both flow and function after revascularization with a disappearance of enhanced glucose uptake. The better linear correlation between flow and % fibrosis after surgery as compared to preoperatively was probably due to improvement of flow values in the mismatch group.

To investigate the rate of metabolism of nitrogen-13 labelled ammonia (13NH3) in different conditions, we have determined the relative amount of unchanged 13NH3 in the blood of dogs, volunteers and transplant patients at different times following injection. In dogs, the determinations were made under basal conditions, during adenosine administration and after coronary occlusion. The results show that adenosine administration increases the metabolic rate whereas coronary occlusion does not affect 13NH3 metabolism. For both human volunteers and transplant patients the metabolic rate of 13NH3 was assessed under basal conditions and during adenosine administration. 13NH3 metabolism proceeds faster in transplant patients than in volunteers under both conditions. Adenosine administration causes a faster 13NH3 turnover in volunteers but not in transplant patients. Application of individual metabolite correction resulted in a 16% decrease in the calculated blood flow compared to uncorrected values. A smaller difference (5%) was observed between correction with mean metabolite values and individually acquired metabolite values.

In this study a new method for assessment of perfusion defects (PDs) derived from myocardial perfusion tomograms was evaluated in patients treated with thrombolytic therapy. Using global constraints and dynamic programming, a model-based delineation algorithm defined myocardial borders, the basal plane and absolute and relative PD size in 49 thallium-201 chloride (201TL CL) and 60 technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) tomograms. Tomographic (single-photon emission tomography: SPET) and planar quantification of PDs was compared to enzymatic infarct size as well as to global (LVEF) and regional ventricular function (RWM) obtained by contrast angiography. The algorithm delineated the myocardium and the valve plane in most cases, even when large PDs were present. Manual correction of the automatic delineation of the basal plane was necessary in less than 20% of the studies. Using 201Tl Cl, LVEF correlated better with tomographic PD (r = -0.67) than with planar PD (r = -0.54). Comparing planar to tomographic imaging using 99mTc-MIBI, a higher correlation with enzymatic infarct size (r = 0.73 vs 0.57) and with global ventricular function (r = 0.64 vs -0.52) was found when tomographic techniques were used. No close correlation between PD and RWM was found. The beneficial effect of thrombolysis was shown by a significant difference of PD in patients with open versus occluded infarct-related vessels. It can be concluded that this new automated algorithm for quantification of SPET perfusion defect size provides a useful tool in evaluating thrombolytic therapy.

Animal studies have indicated that technetium-99m L,L-ethylenedicysteine (99mTc-L,L-EC) may be a promising tracer agent for renal function studies. We have performed a paired study with 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) and 99mTc-L,L-EC in six male volunteers. In both cases, iodine-131-labelled o-iodohippurate was co-injected as an internal biological standard. The analog images between 0 and 30 min p.i. were of identical diagnostic value for both tracer agents. The two renograms were similar in all volunteers. The mean 1-h plasma clearance for 99mTc-MAG3 and 99mTc-L,L-EC was significantly different, respectively 382.9 +/- 17.1 ml/min per 1.73 m2 versus 460.2 +/- 47.7 ml/min per 1.73 m2 (P < 0.003). The urinary excretion after 30 min p.i. was 69.4% +/- 5.6% of the injected dose for 99mTc-MAG3 versus 66.5% +/- 2.5% for 99mTc-L,L-EC (P > 0.05) and after 60 min p.i. respectively 83.1% +/- 3.9% versus 79.8% +/- 4.3% (P > 0.05). 99mTc-L,L-EC has a very low plasma protein binding (31% +/- 6.8%) as compared to 99mTc-MAG3 (88% +/- 5.2%) and a larger volume of distribution. Although the exact mechanism responsible for the high plasma clearance of 99mTc-L,L-EC is not yet fully known, we conclude that this new agent merits further clinical evaluation in patients to establish its value as a renal radiopharmaceutical.

In this study we have compared the characteristics of six labelling kits for the preparation of technetium-99m labelled human serum albumin (99mTc-HSA) and evaluated the usefulness of the various 99mTc-HSA preparations as blood pool tracer agents. The amount of the principal ingredients, i.e. HSA and stannous ions, varies largely between the studied kits and this is probably a reason for the observed differences in the labelling rate. Analysis of the reaction mixtures after labelling of the respective kits with 99mTc showed in each preparation the presence of four to five radioactive components in variable relative amounts. The retention time of the main component on size-exclusion high-performance liquid chromatography (SEC-HPLC) was identical for all preparations. Biodistribution of the HPLC-isolated fractions was studied in mice. The components with the shortest and longest retention times on HPLC show poor retention in the plasma. The three intermediate fractions, including the principal peak, are initially retained relatively well in the blood (60%-70% of the injected dose after 10 min), but clearly to a lower degree than iodine-125 labelled HSA. Moreover, they diffuse out of the vascular compartment at a much higher rate than 125I-HSA. The biological behaviour of the main component of the various preparations was clearly different, despite the identical retention time on SEC-HPLC. Study of the total preparations in mice and a rabbit showed that two of them are cleared rapidly from the blood and cannot be considered valuable blood pool tracers. Diffusion of the other preparations out of the blood is slower but also considerable and compromises their use for ventriculography.

Technetium-99m labelled red blood cells (99mTc-RBCs) are far superior to 99mTc-labelled human serum albumin (99mTc-HSA) for radionuclide ventriculography, but their labelling is more complex, time consuming and risk bearing (in vitro labelling) or suffers from interference by some medications (in vivo labelling). We have now modified HSA by the introduction of mercapto groups with the purpose of preparing stable and practical 99mTc-mercaptoalbumin with long retention in the vascular system, that could replace 99mTc-RBCs. HSA was incubated with N-succinimidyl S-acetylthioacetate (SATA) or N-succinimidyl 2,3-di(S-acetylthio) propionate (SATP) to introduce a chain containing one or two protected sulfhydryl groups on some of the lysine amino groups. After purification by size-exclusion chromatography (SEC), the mercapto groups were deprotected by incubation at alkaline pH or by treatment with hydroxylamine. The reaction products were used with or without SEC purification for direct or exchange labelling experiments with 99mTc at neutral pH. SEC-HPLC was used to determine labelling yields and to isolate pure 99mTc-mercaptoalbumin. Stable 99mTc-mercaptoalbumin complexes could be formed in 90%-95% yield after coupling albumin with SATA or SATP in all molar ratios used followed by deacetylation in one of the mentioned conditions. The most favourable results were obtained after reaction of SATA or SATP with HSA in a 25:1 ratio and deprotection with NH2OH. The stability of the resulting 99mTc-mercaptoacetyl-albumin (99mTc-MA-HSA) and 99mTc-dimercaptopropionyl-albumin (99mTc-DMP-HSA) and their retention in vivo in plasma of mice and rabbits are clearly higher than that of conventional 99mTc-HSA preparations. 99mTc-DMP-HSA approaches the behaviour of 125I-HSA quite well in both animal species. A preliminary study with 99mTc-DMP-HSA in a volunteer showed a retention in the vascular compartment almost identical to that of 99mTc-RBCs and clearly higher than that of a common 99mTc-HSA preparation. The results indicate that these 99mTc-mercaptoalbumins and especially 99mTc-DMP-HSA are very promising as a practical alternative to 99mTc-RBCs.

During a study of C-methyl derivatives of technetium-99m mercaptoacetyltriglycine (99mTc-MAG3) it was found that the isomer of 99mTc-mercaptoacetylglycyl-D-alanylglycine (99m-TC-MAGAG-DA) is superior to 99mTc-MAG3 with regard to its renal excretion characteristics in both mice and the baboon. We have now compared the renal handling of 99mTc-MAGAG-DA and 99mTc-MAG3 in 6 healthy volunteers in a paired study. Renograms of 99mTc-MAGAG-DA show a shorter time to renal maximum and a lower residual renal activity at 30 min post-injection (p.i.). The urinary excretion of 99mTc-MAGAG-DA is higher at both 30 and 60 min p.i. The plasma concentration of 99mTc-MAGAG-DA is lower than that of 99mTc-MAG3 at each moment up to 60 min p.i., and the plasma clearance is accordingly higher. It is concluded that 99mTc-MAGAG-DA is excreted more efficiently than 99mTc-MAG3, but the preparation of 99mTc-MAGAG-DA requires a HPLC purification step, and this limits its practical clinical usefulness.

Serum vitamin D metabolites and urinary calcium excretion; parameters of bone formation (serum alkaline phosphatase, serum osteocalcin); parameters of bone resorption (24 hour hydroxyprolinuria, 2 hour fasting urinary hydroxyproline/creatinine ratio); and parameters of cortical and trabecular bone density, parathyroid hormone (iPTH, COOH terminal assay), and serum minerals (calcium, phosphorus) were followed serially in 55 young adults (21 women and 34 men) from December 1985 until January 1987 at four different times during the year. The effect of a low-dose cyclooxygenase inhibitor (piroxicam 5 mg daily) on the same parameters of bone density and bone turnover when given from December until May, was also evaluated in this study. At the end of the treatment period parameters of bone turnover and bone density were comparable between placebo and piroxicam-treated groups. Therefore, the results of all subjects were pooled in order to investigate seasonal variation. In both sexes, seasonal variation was found not only for 250HD3 but also for 1,25(OH)2D3, serum calcium and phosphorus, urinary calcium excretion, and for bone density at the lumbar spine. Parameters of bone formation (serum osteocalcin and alkaline phosphatase), bone resorption (24 hour urinary hydroxyprolinuria and fasting urinary hydroxyproline/creatinine ratio) and PTH were influenced by this seasonal variation. We conclude that in young adults, a significant seasonal variation occurs, with low winter and high summer values, for serum 25 and 1,25(OH)2D3 for urinary calcium apparently without important influence on parameters of bone turnover or parathyroid activity and for lumbar spine density. Treatment with a low-dose cyclooxygenase inhibitor was without influence on the observed changes.

Varicocele is the most frequent cause of male subfertility. Several invasive and noninvasive techniques can be used to visualize scrotal phlebectasies. In this study sequential scintigraphy after intravenous injection of 99mTc-albumin was compared with tele-thermography. The normal and pathological images are described. The more obvious the clinical condition, the more lesions were revealed by scintigraphy (29.6% in subfertile men suspected of having variococele; 76.9% in patients with first degree varicocele; and 100% in Grades II and III cases). In 55 cases (of a total of 76 cases explored by radioisotopic techniques), the comparison of the thermographic results with the scintigraphy results suggests that scrotal scintigraphy is less sensitive. However, there are more false positive thermographies expressed as a discordance with clinical examination, which indicates higher specificity of scintigraphy. In conclusion scrotal scintigraphy cannot be considered as the screening procedure of first choice for varicocele, but it can give complementary information, especially when thermographic results are at variance with the clinical examination.

We have studied the influence of granulocyte labelling with commercially available 111In-oxine, tropolone (trop) or home made 111In-Mercapto pyridine (Merc) prepared by the method of Thakur (1985) on the cell structure by electron microscopy and on the cell function by enzymatic tests, random migration, chemotaxis, phagocytosis and bactericidal activity. The granulocytes were labelled with 400 microCi 111In-oxine in saline or 111In-trop or Merc in plasma. The effect of the chelating agents with and without addition of the tracer was studied (n = 4) with varying concentrations: 5-10 micrograms/ml oxine, 10-160 micrograms/ml trop and 1-4 micrograms/ml Merc. Chemotaxis and random migration were not affected by 111In-trop and clearly suppressed by 111In-oxine and Merc; the other tests were normal. The cell structure was disturbed by Merc. The labelling efficiency was excellent with oxine (90%), acceptable with trop (30%-80%) and poor with Merc (10%-25%). Without 111In, chemotaxis and random migration were normal up to a concentration of 80 micrograms/ml trop, 8.5 micrograms/ml oxine and 1 microgram/ml Merc. With addition of 111In, chemotaxis and random migration were unaffected up to 80 micrograms/ml by trop and markedly suppressed by Merc and oxine. It is concluded that labelling with 111In-trop assures intact cells.

In order to evaluate the diagnostic contribution of brain SPECT imaging with 99mTc-HMPAO in cerebrovascular disease, we examined 92 stroke cases (144 lesions), 2 hematoma cases and 30 cases with transient neurologic symptoms. Abnormal tracer distribution is visible as zones of either hypoactivity or hyperactivity (border zone hyperemia or luxury perfusion). Remote vascularization changes could also be found (crossed cerebellar diaschisis or ipsilateral cortical perfusion reduction in thalamic or capsula interna lesions). Both X-ray CT and blood flow SPECT have comparable sensitivity in the exploration of cerebral infarction, with detection in, respectively, 89.5% and 87.5% of the lesions. False negative scintitomographic images are frequently recorded in small lacunar infarcts within the basal ganglia and white matter (capsula interna). Some early infarcts and asymmetry of brain perfusion in patients with transient neurologic symptoms are frequently not detected by CT. An additional advantage of blood flow SPECT is its ability to visualize remote blood flow changes and the changing pattern of vascularization of ischemic lesions and their surrounding areas including hyperemia.

Two cases of mediastinal localization of parathyroid adenoma are presented, in which technetium-thallium subtraction scintigraphy yielded a positive result. Both patients had already undergone a negative surgical neck exploration. We suggest that, in case of negative subtraction scintigraphy and negative surgical exploration in proven primary hyperparathyroidism, subtraction scintigraphy should be repeated with emphasis on the superior mediastinum, and in all cases, the use of a non-zoom, large field of few procedure is recommended for technetium-thallium subtraction scintigraphy.

The quantification of organ volumes from SPECT images suffers from two major problems: image segmentation and imperfect system transfer function. Image segmentation defines the borders of an organ and allows volume measurements by counting the voxels inside this contour in all slices containing parts of this organ. A review of the literature, showed that several investigators use a fixed threshold (FT) to determine the organ pixels. It is our aim to demonstrate that the threshold has to be adapted to every single case because its value is dependent upon several factors, such as size and contrast. Therefore a threshold selection algorithm, based on the gray level histogram (GLH), is evaluated. It is nearly impossible to calculate and eliminate errors induced by the complex system response function. A correction method based on linear regression is proposed. By minimizing the relative error (sigma), a linear correlation (Y = AX + B) between the true volume (Y) and the measured volume (X) is established for three fixed thresholds (30%, 40%, 50%) and for the GLH method. The methods are evaluated on a series of nineteen phantoms with a volume range between 9.8 and 202.5 ml. The relative error is minimal for the GLH method. The whole procedure is semi-automated and virtually operator independent.

Liver scintigraphy demonstrated areas of increased radiocolloid uptake in three cases with obstruction of the superior vena cava and extensive collateral circulation through the veins of the thoracic wall. The pattern of the hyperactive zones is indicative of predominant vascularization of the liver via the umbilical vein, with high colloid particle deposition in the quadrate lobe and adjacent part of the right lobe. These liver regions vascularized by the first intrahepatic branches of the umbilical vein as demonstrated by postmortem angiography, probably extract a great portion of the tracer dose, resulting in localized hyperactivity. An identical liver scan image was, however, found in a fourth case without evident superior vena cava syndrome. In this patient, presenting with a bronchus carcinoma with paratracheal metastatic lymph nodes, there is no explanation metastatic lymph nodes, there is no explanation (collateral circulation without vena cava obstruction?) for the abnormal tracer distribution within the liver.

All of the packing inside the metal transport cylinder of some sodium iodide (131I) therapy capsules, especially the filling material surrounding the lead container, was found to be contaminated with 131mXe, a daughter radionuclide of 131I. Therefore, users should open the containers only under a well-ventilated hood.

Bedside myocardial scintigraphy was performed on 149 patients admitted to the Coronary Care Unit (CCU), after IV injection of 74 MBq 201Tl, using a mobile gamma camera (Dynamo). The study was displayed on Polaroïd pictures, without any image treatment, and read by two independent readers. Clinical history, findings, and final diagnosis were assessed by an independent clinician. The following conclusions were reached: 1) The sensitivity of the study for the detection of a recent myocardial infarction (MI) was 0.84 with a specificity of 0.87. 2) There was a good correlation between scintigraphic and ECG localization. 3) No firm correlation was found between scintigraphic and enzymatic estimates of infarct size. 4) Abnormal visualization of the right ventricle was probably associated with more extensive infarction.

Over the past 5 years, we have encountered 6 cases of diffuse pulmonary uptake of 99m-Tc bone-scanning agents (incidence, 0.04%). To assess the significance of this phenomenon, we reviewed all of the cases reported since 1974 (Including our series, a total of 32 cases). Three groups can be discerned, the first consisting of 24 patients without radiological calcifications in the lungs and with hypercalcemia of different origins (mostly hyperparathyroidism). Of the eight autopsies performed in this group, seven revealed extensive calcifications in alveolar walls and lung vessels; the other autopsy showed no calcification at all and only bronchopneumonic lesions. The second group consists of 6 patients in chronic dialysis. The last group consists of 2 patients having diffuse pulmonary alveolar microlithiasis with extensive radiologic calcifications. The mechanism of lung uptake of 99m-Tc bone-imaging agents is probably the same as that of bone uptake (chemisorption on hydroxyapatite crystals), although other uptake mechanisms have also been discussed. Bone scintigraphy can be useful in the detection of early pulmonary calcifications, which have been associated with impaired pulmonary function and, due to their size, are generally not detected by X-ray.

The uptake of 99mTc in the small joints of the hand has been compared to various other mesures of inflammation in 22 patients with rheumatoid arthritis. The 99mTc uptake in the finger joints can reflect both disease activity at a given time and change in activity over a period of time. The place of Tc uptake amongst other measures of inflammation, from the point of view of the 'relative efficiency' of the assessment method, is rather inferior. In evaluating the effect of antiphlogistic drugs on local inflammation, techneticum uptake may, however, prove more discriminating than grip-strength or the number of painful joints, since the latter measures depend largely on the degree of destruction.

A method for multiparametric quantitative cerebral angioscintigraphy is described. For the evaluation of the symmetry of hemispherical bolus transit the following parameters were used: the cumulative L/R hemispheric ratios expressed in arctangent values and the sequential hemispheric activity difference. Both the sensitivity and specificity of this technique for detection of proven stenosis of carotid or cerebral arteries (25 cases) were 80%, in comparison with 60% for computerized axial tomography. A few clinical examples illustrate the diagnostic utility of quantitative cerebral angioscintigraphy. The value of the different quantitative parameters is discussed and compared with other similar studies. With regard to the complementary role of computerized axial tomography and serial cerebral scintigraphy the results of other authors were confirmed. Considering the broad field of application for dynamic brain scintigraphy and the fact that both sensitivity and specificity of this exploration are comparable to, or even better than, CT, it is our opinion that isotopic exploration remains a reliable detection method for cerebrovascular disease.