Effective dose equivalent from radiopharmaceuticals

Tc-99m Ethylenedicysteine and Tc-99m Dimercaptosuccinic Acid Scintigraphy-Comparison of the Two for Detection of Scarring and Differential Cortical Function

Context:

The differential cortical function obtained by Tc-99m EC is comparable to that of Tc-99m DMSA. However, identification of scars on Tc-99m EC images needs to be studied.

Aims:

The aim of the study is to evaluate role of Tc-99m EC for detection of scarring and differential cortical function by comparing with Tc-99m DMSA.

Settings and Design:

Prospective observational study of recurrent UTI; minimum 6 weeks after acute episode; when urine examination is negative for pus cells.

Materials and Methods:

Forty-seven children with normal positioned kidneys underwent Tc-99m EC and DMSA scintigraphy. The DRF and cortical phase images of both studies in the same image matrix size were evaluated by two independent observers for scarring; Tc-99m DMSA was considered as the gold standard.

Statistical analysis used:

MS Excel 2007 and GraphPad Instat V3.1 and ROC analysis.

Results:

There was no significant difference in the detection of scarring using two studies with Cohen's kappa coefficient (κ) 0.932. The sensitivity and specificity of Tc-99m EC for detection of scarring was 98.75% and 99.15%, respectively. There was good agreement between the differential cortical function calculated using two studies.

Conclusions:

The summed Tc-99m EC images with an acceptable high image contrast allow detection of cortical scarring in patients with normal kidney positions. It is an excellent single-modality comprehensive investigational agent for renal parenchymal defects, function, and excretion evaluation with the added advantages of lower cost, convenience, and low radiation exposure to the child.

Technetium-99m-N,N-ethylenedicysteine and Tc-99m DMSA scintigraphy in the evaluation of renal parenchymal abnormalities in children

Technetium-99m dimercaptosuccinic acid (Tc-99m DMSA) as a static renal agent is currently the most frequently used agent in the detection of renal scarring, and allows accurate calculation of differential renal function (DRF). But this agent has some disadvantages such as relatively higher radiation dose and time consumption.

METHODS

The purpose of this study was to evaluate the potential of summed image that obtained from parenchymal phase of the dynamic technetium-99m-N,N-ethylenedicysteine (Tc-99m EC) scintigraphy in the detection of renal parenchymal defects and in the estimation of DRF, and to compare the results of this method with those of Tc-99m DMSA scintigraphy. The uptake ratios of the kidney to body background were also calculated for these two methods. Twenty-nine children with various renal disorders underwent both static Tc-99m DMSA and dynamic Tc-99m EC scintigraphy. The cortical analysis of Tc-99m EC scintigraphy was performed on the summed image obtained from dynamic images using the time interval between the first 45-120 sec.

RESULTS

There was a very close correlation between these two methods with respect to DRF (r = 0.99). In the detection of renal parenchymal lesions, scintigraphy with Tc-99m DMSA detected more lesions, and the sensitivity and specificity of the summed Tc-99m EC images were calculated as 92.6% and 100%, respectively. In addition, the ratios of mean uptake values for Tc-99m DMSA and Tc-99m EC images were 7.59 +/- 2.17 and 2.95 +/- 0.91, respectively. This ratio of Tc-99m EC seems to be acceptable and allows good delineation of the kidneys. But, the main disadvantages of the summed Tc-99m EC images in comparison with static Tc-99m DMSA images are the use of only posterior projection that may be an important drawback in patients with abnormal kidney positions, lower image counts and higher pixel size because of dynamic acquisition.

CONCLUSION

These results show that summed Tc-99m EC images with an acceptable high image contrast provide an accurate DRF calculation in patients without abnormal kidney positions and allow the detection of most renal parenchymal abnormalities. However, Tc-99m DMSA scintigraphy remains the gold standard method because of its well known advantages.

Radiation doses to patients undergoing scoliosis radiography

In this study we computed the radiation doses associated with scoliosis radiography and investigated how these radiation doses are influenced by the weight of the patient. We recorded the radiographic technique factors of 61 consecutive patients (46 females and 15 males) undergoing scoliosis radiography. A wedge-shaped aluminium filter attenuated the X-ray beam in the "chest region" relative to the "abdomen region". X-ray tube air kerma output factors (microGy mAs-1) and half value layers (HVLs) were determined experimentally for the "chest region" and "abdomen region". The energy imparted to each patient was computed from the air kerma area product, X-ray beam HVL and measured patient thickness. Values of patient effective dose were obtained using effective dose-to-energy conversion factors for specified radiographic projections, taking into account each patient's weight. The median patient age was 17 years, and the median patient weight was 53 kg. Entrance skin air kerma values in the "chest region" were approximately a factor of four lower than those in the "abdomen region". The air kerma values increased by a factor of two when the patient weight increased from 30 kg to 70 kg. Approximately 80% of the total energy imparted to a patient undergoing a scoliosis examination was in the "abdomen region", with the remaining 20% imparted to the "chest region". Energy imparted increased with patient weight, and was approximately 3 mJ for a 30 kg patient and approximately 8 mJ for a 70 kg adult patient. Effective doses showed little correlation with patient weight, with an average-sized patient (50 kg) receiving an effective dose of approximately 140 microSv. Patients undergoing scoliosis radiography receive effective doses that are low in comparison with other types of radiographic examination.

The value of additional carpal box radiographs in suspected scaphoid fracture

RATIONALE AND OBJECTIVES

Carpal Box (CB) radiographs, transverse and longitudinal, produce elongated and magnified views of the carpus. These radiographs can be used after carpal injury, in addition to conventional scaphoid x-rays. In this study, the use of CB radiographs was evaluated in patients with possible scaphoid fracture.

METHODS

Seventy-one consecutive patients who presented at the First Aid department from May 1994 to May 1995 were included. All patients were examined for scaphoid fracture after a fall on the out-stretched hand. If a scaphoid fracture was seen on the scaphoid x-rays, patients were immobilized. If the x-rays remained negative or dubious for fracture, additional transverse and longitudinal CB radiographs were obtained. If CB radiographs remained negative or inconclusive, patients were referred for three-phase bone scintigraphy. The results of independent and masked judgment by three different observers were used for an inter- and intraobserver analysis.

RESULTS

Twenty of 71 patients initially showed a scaphoid fracture on the conventional scaphoid x-rays, 41 were negative, and 10 inconclusive. All 41 negative patients remained negative on CB radiograph; however, the bone scintigraphy was positive for scaphoid fracture in 11 patients and in 9 patients a hot spot elsewhere in the carpus was found. Of the 10 patients with inconclusive x-rays, 2 showed a clear fracture of the scaphoid on CB radiograph, 5 were negative, and 3 remained inconclusive. The agreement between observers, calculated in kappa values, was highest in CB radiographs.

CONCLUSIONS

In the diagnosis of scaphoid fracture, Carpal Box radiography is of limited value in patients with clinically suspected scaphoid fracture. In two of 10 patients with initial dubious scaphoid x-ray, bone scintigraphy can be avoided. Furthermore, the reliability of the interpretation of the radiographs is increased by additional Carpal Box radiography.

Magnetic resonance imaging versus bone scintigraphy in suspected scaphoid fracture

Magnetic resonance imaging (MRI) has become increasingly useful in the evaluation of musculoskeletal problems, including those of the wrist. In patients with a wrist injury, MRI is used mainly to assess vascularity of scaphoid non-union. However, the use of MRI in patients in the acute phase following carpal injury is not common. Three-phase bone scintigraphy is routinely performed from at least 72 h after injury in patients with suspected scaphoid fracture and negative initial radiographs. We evaluated MRI in this patient group. The bone scan was used as the reference method. Nineteen patients were included. Bone scintigraphy was performed in all 19 patients, but MRI could be obtained in only 16 (in three patients, MRI was stopped owing to claustrophobia). In five patients, MRI confirmed a scintigraphically suspected scaphoid fracture. In one patient, a perilunar luxation, without a fracture, was seen on MRI, while bone scintigraphy showed a hot spot in the region of the lunate bone, suspected for fracture. This was confirmed by surgery. In two patients, a hot spot in the scaphoid region was suspected for scaphoid fracture, and immobilization and employed for a period of 12 weeks. MRI was negative in both cases; in one of them a scaphoid fracture was retrospectively proven on the initial X-ray series. In another two patients, a hot spot in the region of MCP I was found with a negative MRI. In both, the therapy was adjusted. In the remaining six patients, both modalities were negative. We conclude that in the diagnostic management of patients with suspected scaphoid fracture and negative initial radiographs, the use of MRI may be promising, but is not superior to three-phase bone scintigraphy.

D2-receptor imaging with [123I]IBZM and single photon emission tomography in psychiatry: a survey of current status

D2-dopamine receptors can be visualized in the human brain in vivo by Single Photon Emission Tomography (SPECT) and the radiolabeled benzamide [123I]IBZM. The present paper reviews the current status of this type of functional brain imaging with respect to basic methodological aspects, data analysis and quantification. The results from published clinical studies in different psychiatric patient populations and normal controls with [123I]IBZM are reviewed. [123I]IBZM-SPECT is a powerful tool for the investigation of D2-dopamine receptor status in psychiatric disorders, different types of drug treatment as well as therapeutic and side effects of pharmacologic agents. However, there still is a need for standardized imaging times and image-processing procedures. Advantages and disadvantages of SPECT with special regard to Positron Emission Tomography (PET) are also discussed.

Normal fasting volume and postprandial emptying of the denervated donor gallbladder in liver transplant recipients

BACKGROUND/AIMS

Truncal vagotomy causes gallbladder dilatation and possibly cholelithiasis. During liver transplantation, when the gallbladder is transplanted with the donor liver, the gallbladder and liver are extrinsically denervated. The aim of this study was to determine whether extrinsic denervation affects gallbladder volume and postprandial emptying.

METHODS

To evaluate fasting gallbladder volume, 26 transplant recipients underwent ultrasonography. Twenty-eight normal volunteers were controls. To evaluate postprandial contractility, seven transplant recipients underwent radionuclide gallbladder-emptying studies. Gastric emptying and cholecystokinin release were simultaneously determined after a fatty meal to exclude a difference in gallbladder stimulus. Sixteen normal volunteers were controls.

RESULTS

There were no differences in fasting gallbladder volume or postprandial contractility, gastric emptying, and cholecystokinin release between transplant patients and controls. Median fasting and postprandial gallbladder volumes for the transplant recipients (95% confidence) were 16 mL (12-34 mL) and 3 mL (0-8 mL), respectively, and for controls were 18 mL (13-21 mL; P = 0.73) and 3 mL (1-6 mL; P = 0.97), respectively.

CONCLUSIONS

These data do not show gallbladder dilatation or impaired postprandial gallbladder contraction in the extrinsically denervated gallbladder. This finding suggests that gallbladder dilatation may be caused by the unopposed activity of the sympathetic system after truncal vagotomy.

Radioisotopic labels for blood cell survival studies: a review

The different methods of labeling blood cells, in particular erythrocytes and platelets, for survival studies are reviewed. Besides the technical information about these procedures, attention is also paid to the indications of blood cell survival studies, the effective dose equivalent involved and the interpretation of the resulting data. In the final section the possibilities created by dual-labeling procedures are discussed.

Radiation doses obtained from 99mTc-labelled human milk fat globule monoclonal antibodies

Human milk fat globule (HMFG) monoclonal antibodies labelled with 123I and 111In are used for the diagnosis of ovarian and breast cancer. Methods have been developed to label HMFG with 99mTc and this study reports on the subsequent radiation dose delivered. The 99mTc HMFG1 distribution was obtained in 5 normal female baboons up to 71 h after administration. The liver, kidneys, bladder and whole body were identified as source organs and total absorbed doses for the target organs were 0.054 (kidneys), 0.013 (liver), 0.140 (bladder), 0.010 (ovaria), 0.004 (bone marrow), 0.002 (thyroid), 0.003 (heart wall), 0.017 (uterus) and 0.005 mGy/MBq (whole body). The effective dose was 0.014 mSv/MBq.

Effective dose from radiopharmaceuticals

The effective dose, as defined by the International Commission on Radiological Protection (ICRP 1991), provides a possibility of expressing the radiation risk to patients undergoing different radiodiagnostic procedures by means of a single figure. This has been obtained by introducing organ or tissue weighting factors reflecting the radiation sensitivity of the organs. Such weighting factors were first published by the ICRP in publication 26 (1977), and have now been revised in publication 60 (1991). The effective dose for almost all radiopharmaceuticals in clinical use has been recalculated using the new weighting factors from ICRP 60 (1991) and compared with results from former calculations. A slight decrease in the numerical value for the effective dose has been observed, on average 11%. However, this does not correspond to a decrease in the estimated risk from the irradiation, since this has been re-evaluated and found to be higher than earlier believed (NAS 1990; ICRP 1991).

Scintigraphy in the clinical evaluation of disorders of mineral and skeletal metabolism in renal failure

In patients with renal bone disease skeletal and extra-skeletal abnormalities can be visualised using conventional bone scintigraphy. Some of these abnormalities are associated with characteristic scintigraphic appearances, which are reviewed in detail, and the possible mechanisms involved are discussed. Specific imaging with iodine 123 serum amyloid P component and iodine 131 beta 2-microglobulin is also discussed in the diagnosis of beta 2-microglobulin amyloidosis specific to patients on dialysis. In the light of available evidence, it appears that bone scintigraphy plays, so far, a limited role in the clinical evaluation of skeletal and extra-skeletal abnormalities in chronic renal failure. The potential role of bone scintigraphy in identifying patients with aluminium-related bone disease needs to be investigated further, and in this respect special attention must be given to the problem of high soft-tissue activity associated with impaired renal function. Timing haemodialysis sessions before scintigraphic imaging deserves wider recognition as it reduces high soft-tissue activity, thereby allowing bone uptake to be assessed more accurately. Specific imaging of amyloidosis resulting from beta 2-microglobulin deposition is a promising technique, but the relative value of the two proposed radiopharmaceuticals needs further clarification.

Athletes' pseudoanaemia

To characterize the so-called pseudoanaemia of endurance-trained athletes, the plasma volume (PV), red cell volume (RCV) and total blood volume (TBV) of 12 male and 12 female athletes and 5 male and 5 female nonexercising controls were measured using 125I-labelled human serum albumin and 51Cr-labelled erythrocytes. The mean PV of the male athletes (52.8 ml.kg-1) was 37.5% higher than that of the controls (38.4 ml.kg-1), while the 18.1% increase measured in the female runners (51.5 ml.kg-1) over the controls (43.6 ml.kg-1) was a novel observation. Although the RCV was significantly greater (34.7%) in male athletes (32.6 ml.kg-1 vs 24.2 ml.kg-1 in the controls), a similar elevation (3.6%) was not found in the female athletes (25.9 ml.kg-1) compared to the sedentary women (22.8 ml.kg-1). This could have been due to iron-limited erythropoiesis because the RCV of the female athletes defined as clinically anaemic was markedly lower that of the nonanaemic women (P less than 0.05). The elevated plasma protein mass and concentration measured in the athletes partly accounted for their expanded PV. It was concluded that the decreased blood haemoglobin levels reported in the endurance athletes was largely a dilutional effect.

Increased volume and decreased emptying of the gallbladder in large (morbidly obese, tall normal, and muscular normal) people

Impaired gallbladder emptying has been suggested as a possible factor in the pathogenesis of gallstones. Obese people have an increased incidence of gallstones, but there is no evidence of this in nonobese large people. This study was undertaken to determine if abnormal gallbladder motility is present in obese people. Fasting gallbladder volumes were determined using real-time ultrasound in 18 morbidly obese subjects whose weights were in a steady state [45 kg (100 lb) over ideal weight or twice expected weight for age and height; 9 males, 9 females], 18 age- and sex-matched volunteers of average size, and 18 nonobese large normal males (9 tall, 9 muscular). Gallbladder emptying studies with 99mtechnetium-diisopropyliminodiacetic acid were performed using 200 ml of 10% cream as a stimulus. The small-volume liquid fatty meal contained 113indium-diethylenetriaminepentaacetic acid to control for differences in gastric emptying in obesity. The gallbladder emptying rate in large people, both obese and nonobese, was less than that in normals of average size (p = 0.05). Fasting gallbladder volumes in large people were: obese, 41 ml (37-66 ml) (median; 95% confidence limits); nonobese large normal, 40 ml (27-43 ml). These values were greater than in normals of average size [17 ml (14-21 ml) (p = 0.03)]. Postprandial gallbladder volumes were also greater in large people: obese, 15 ml (8-23 ml); nonobese large normal, 20 ml (13-23 ml) compared with 2 ml (1-5 ml) in normals of average size (p less than 0.05). There were no differences between obese and nonobese large people. There were no differences in gastric emptying rates or in cholecystokinin, gastrin, motilin, and secretin release between obese and normal subjects. Gallbladder volume is crudely proportional to body size. Although fasting and postprandial volumes are greater in obesity, this is also present in nonobese, relatively size-matched controls. These data do not support a role for impaired gallbladder emptying in gallstone formation in obese patients whose weights are in a steady state.

Age and sex specific population doses (SED (somatic effective dose equivalent) and GSD (genetically significant dose equivalent)) due to nuclear medicine procedures in The Netherlands

Age- and sex-specific data were obtained concerning nuclear medicine procedures performed in The Netherlands in 1984. The average annual per capita procedure frequency amounted to 0.011. Using recent organ dose data for a large number of common radiopharmaceuticals (ICRP, Publ. 52/53, 1987) the somatic effective dose equivalent (SED) and the genetically significant dose equivalent (GSD) were calculated. The collective SED yielded 575 person-Sv per annum. The annual per capita SED was 40 microSv. The Genetically Significant Dose turned out to be approximately 3.2 microSv per person per year.

Myocardial scintigraphy with 201thallium in pediatric cardiology: a review of 52 cases

We report our experience of myocardial scintigraphy with 201thallium (201Tl) in 52 children, aged 4 days to 18 years, in which 80 studies were made primarily to demonstrate or exclude impaired myocardial perfusion. For analysis, the patients were divided into the following eight groups: group I, coronary artery malformations (five patients); group II, Kawasaki's syndrome (six patients); group III, arterial switch operation (seven patients); group IV, dilated cardiomyopathy (18 patients); group V, hypertrophic cardiomyopathy (four patients); group VI, myocardial dysfunction after surgery for congenital heart disease (five patients); group VII, pulmonary atresia (three patients); and group VIII, miscellaneous (four patients). Myocardial scintigraphy was performed with a planar or tomographic technique at rest or after exercise (four patients). Isotope-uptake defects, indicating impaired myocardial perfusion, were present in 14 patients, including small infants. Defects were seen in all groups except those with hypertrophic cardiomyopathy and pulmonary atresia. The absence of such defects in several of the patients with Kawasaki's syndrome was particularly valuable as it made coronary angiography unnecessary. In the other groups of patients myocardial scintigraphy was a valuable adjunct to other investigations.

Estimates of the effective dose equivalent, HE, in positron emission tomography studies

The effective dose equivalent, HE, can be used as a standard radiation dose parameter in all imaging modalities that use ionizing radiation, including positron emission tomography (PET). A simplified method for evaluating approximate HE values for the positron emitters carbon 11, nitrogen 13, oxygen 15 and fluorine 18 is presented. HE values for a range of PET studies have been computed based on biodistribution data available in the scientific literature. Low-dose PET studies include a bolus administration of 1030 MBq CO15O (HE = 1 mSv) and 74 MBq [18F]-L dopa (HE = 1.3 mSv). High-dose PET studies include a 1-h (steady-state) inhalation of a total of 9250 MBq C15OO (HE = 9.4 mSv). The mean HE value of 13 diverse PET studies was computed to be 4.5 mSv.

Radiation doses and detriment from chest x-ray examinations

Radiation dose distributions for chest x-ray examinations have been measured in a Rando phantom for three views (AP, PA and lateral) as a function of kVp. On the basis of these data, the relationship between the surface dose, energy imparted and the effective dose equivalent have been determined. The mean energy imparted in a typical chest examination (PA + lateral views at 100 kVp) is 1.7 mJ and the corresponding value of the effective dose equivalent, HE, is 42 muSv. The measured radiation doses associated with chest x-rays were compared with the predictions of Monte Carlo calculations. The average difference between Monte Carlo and measured data for the HE was only about 16%. Demographic features (age/sex) of patients undergoing chest x-rays were investigated, and a population irradiation factor (PIF) introduced to estimate the radiation detriment to this population. The probability of expressed radiation-induced detriment to the patient population from chest x-ray examinations was computed to be about one half of that expected for a normal adult (working) population receiving the same dose. The radiation risk associated with chest x-ray examinations for this population was estimated to be less than 0.3 fatal cancers plus serious genetic disorders in the first two generations per million patient examinations.

The use of the effective dose equivalent, HE, for 99mTc labelled radiopharmaceuticals

Using the concept of effective dose equivalent, HE, it is shown that a knowledge of the detailed biodistribution data in most organs and tissues taking up 99mTc labelled radiopharmaceuticals is unnecessary for the calculation of radiation risk. Reasonably precise dosimetry (+/- 25%) can be obtained from urine excretion data alone providing there is no significant uptake within the gonads or the thyroid. Special attention should only be paid to absorbed dose measurements in red bone marrow, skin, lungs, gonads and thyroid, with the greatest attention directed toward the retention and dosimetric aspects of radioactivity in the latter two organs. An example HE calculation for 99mTc labelled d,1-HMPAO is presented to illustrate the importance of these specific five organs to radiation risk.

Renal parenchymal damage on DMSA-scintigraphy in pelviureteric obstruction

During a 1.5 year period 21 children were investigated with 99-m-technetium dimercaptosuccinic acid (DMSA) before operation for hydronephrosis due to pelviureteric obstruction. The age at investigation was 0.2-11.5 years. Fourty-two kidneys were examined. Hydronephrosis existed on the right side in 8 cases, left side in 9 and bilateral in 4 cases. Seventeen kidneys had no obstruction. The scintigraphy was interpreted as normal in 19 kidneys. Decreased isotope uptake was found in 23 kidneys and localized to the upper pole area in 19 kidneys, middle-lateral part in 7, lower pole area in 15 and the middle-medial part in 12 kidneys. There were no predominance for any part of the kidney to be affected by parenchymal damage. In 8 children investigated before the age of 1 year, 4 of 10 hydronephrotic kidneys revealed normal DMSA scintigram. DMSA scintigraphy delineates functioning renal parenchyma. DMSA scintigraphy delineates functioning renal parenchyma. It can be recommended as a routine method for evaluation of the renal parenchyma before surgery and for follow up studies in all ages of childhood.

Daily serial evaluation of left ventricular function with equilibrium radionuclide ventriculography following thrombolysis during acute myocardial infarction

The changes in ventricular function after reperfusion by coronary thrombolysis are important when deciding about further definitive treatment necessary to ensure long-term vessel patency. The purpose of this study was to evaluate the early changes in left ventricular function after reperfusion. Left ventricular function was serially evaluated for 10 days in a group of 18 patients receiving intracoronary thrombolytic therapy for an acute myocardial infarction. Comparison of the global ventricular function in the successfully and unsuccessfully reperfused groups of patients showed significantly better function in the successful group than the unsuccessful group after the first day, which was maintained for the entire study period. Global and regional ventricular function in the successfully reperfused patients showed significant early improvement during the initial 72 h with maintenance of this improvement for the study period of 10 days. In the patients in whom reperfusion was unsuccessful, regional ventricular function showed no change, while the global function declined from day 5 to day 8 of the study period. This study then confirms the significant improvement in ventricular function after successful reperfusion. The time course pattern of the change in ventricular function indicates that the most significant improvement occurs within the first 72 h after reperfusion. These changes are similar to those previously reported in experimental animals.

Radionuclide tests for the assessment of intestinal permeability

14C labelled-D-mannitol and aquo (ethylene-diaminetriacetoacetic acid) 51chromium (III) (51Cr EDTA) have been evaluated as markers of intestinal permeability in twenty-four healthy control subjects, sixteen patients with recently diagnosed coeliac disease and twenty subjects with coeliac disease in remission on a gluten-free diet. The percentage excretion of 14C mannitol in urine collected for 6 h was significantly less in patients with coeliac disease (mean 6.7%) than controls (mean 13.5%). Conversely the excretion of 51Cr EDTA was significantly greater in patients with coeliac disease (mean 1.23%) compared with controls (mean 0.28%). The mean ratio of the percentage excretion of 51Cr to the percentage excretion of 14C was 0.29 in patients with untreated coeliac disease compared with 0.023 for healthy control subjects (P less than 0.001). Patients with untreated coeliac disease were clearly separated from control subjects by use of the 51Cr EDTA: 14C mannitol ratio but not by the excretion of independent markers.

Evaluation of renal parenchyma in children by DMSA scintigraphy, X-ray computed tomography and intravenous urography

The demonstration of diminished or scarred renal parenchyma in children is often the decisive factor in determining the future management of children with urinary tract malformations. Renal scintigraphy using technetium 99m-labelled dimercaptosuccinic acid (DMSA), computed tomography (CT) and intravenous urography (IU) were used to evaluate the renal parenchyma prior to ureter re-implantation in a series of 13 children. Their ages ranged from 5 months to 3 years 8 months. The indication for operation was ureteric reflux in 8 children and distal ureteric stenosis in 5. CT was performed on a Toshiba TCT-80 scanner. Renal scintigraphy was performed 3 hours after intravenous injection of DMSA. Compared with IU, DMSA imaging gave more information about the renal parenchyma in 6 children, gave equal information in 6 and less in 1. Compared with CT, DMSA imaging gave more information in 2 children, was equally informative in 8 and less so in 3. Accordingly, DMSA imaging was judged to be more sensitive than IU and as sensitive as CT. DMSA imaging can be used both for the initial evaluation and for follow-up assessment of renal parenchymal damage.

Specificity of indium-111 granulocyte scanning and fecal excretion measurement in inflammatory bowel disease--an autoradiographic study

The validity of 111In granulocyte scanning and fecal excretion measurement, as a reflection of loss of cells into the gastrointestinal tract, was studied using an autoradiographic technique in 11 patients in whom 111In granulocyte scan and colonoscopy were carried out simultaneously. 111In granulocytes were injected 1.5-4 hr prior to colonoscopy, and intraluminal fluid, mucosal brushings, and colonic biopsies were collected during the colonoscopy. In two patients with no histological evidence of inflammatory bowel disease, and four patients with clinically and histologically inactive inflammatory bowel disease, no 111Indium was detected in fluid, brushing, or biopsies. In five patients with active disease, 85% of the 111In activity in colonic fluid was precipitated by low-speed centrifugation. Autoradiography confirmed that the label remained attached to whole granulocytes in colonic fluid and mucosal brushings. Studies on biopsies, at intervals up to 4 1/2 hr following labeled granulocyte injection, demonstrated labeled polymorphonuclear neutrophils (PMNs) on the inflamed epithelial surface, with occasional cells in crypt abscesses by 110 min. We conclude that the techniques of 111In granulocyte scanning and fecal counting in patients with IBD are specifically measuring cell loss; labeled PMNs are capable of migrating through the gastrointestinal mucosa, in active disease, within 2 hr of administration.

A comparison of the economics of xenon 127, xenon 133 and krypton 81m for routine ventilation imaging of the lungs

We have compared the cost of providing routine lung ventilation scintigraphy using 127Xe with other radioactive gases in 100 patients. The physical properties of 127Xe permit a logical imaging sequence where a ventilation study is only carried out if indicated by perfusion scintigraphy which is performed first. With 133Xe, all patients must be ventilated prospectively, or a preselection carried out based on radiographic appearances at the time of imaging. This results in a greater number of ventilation studies than with 127Xe. Despite the greater cost per study of 127Xe, the overall cost of providing a routine diagnostic service with this gas is no more than that of using 133Xe in selected patients. The cost of ventilating all patients prospectively with 133Xe is considerably greater than using 127Xe only when indicated by abnormal perfusion images. If ventilation imaging is to be available at all times, either isotope of xenon costs very much less than 81Krm. We conclude that 127Xe is the radiopharmaceutical of choice for routine lung ventilation scintigraphy.