Radiation exposure in stent-grafting of abdominal aortic aneurysms.

In recent years, endovascular stent-grafting of abdominal aortic aneurysms has become more and more common. The radiation dose associated with these procedures is not well documented however. The aim of the present study was to estimate the radiation exposure and to simulate the effects of a switch from C-arm radiographic equipment to a dedicated angiographic suite. Dose-area product (DAP) was recorded for 24 aortic stent-grafting procedures. Based on these data, entrance surface dose (ESD) and effective dose were calculated. A simulation of doses at various settings was also performed using a humanoid Alderson phantom. The image quality was evaluated with a CDRAD contrast-detail phantom. The mean DAP was 72.3 Gy cm(2) at 28 min fluoroscopy time with a mean ESD of 0.39 Gy and a mean effective dose of 10.5 mSv. If the procedures had been performed in an angiographic suite, all dose values would be much higher with a mean ESD of 2.9 Gy with 16 patients exceeding 2 Gy, which is considered to be a threshold for possible skin injury. The image quality for fluoroscopy was superior for the C-arm whilst the angiographic unit gave better acquisition images. Using a C-arm unit resulted in doses similar to percutaneous coronary intervention (PCI). If the same patients had been treated using dedicated angiographic equipment, the risk of skin injury would be much higher. It is thus important to be aware of the dose output of the equipment that is used.

Dose-image optimisation in digital radiology with a direct digital detector: an example applied to pelvic examinations.

In diagnostic radiology increasing attention has been focused on dose reduction while maintaining a clinically good image quality. With the use of digital detectors balancing dose vs image quality is done differently than in film-screen radiography, since dose and image brightness are uncoupled in digital imaging. In this study a new direct digital detector (flat-panel detector) was used in a dose-image optimisation of a simulated pelvic examination. X-ray images were taken with a direct digital detector (DDD), of the pelvic of a phantom using varying tube current (varying stochastic noise). The entrance surface dose was measured for each image. These images were scored by two radiologists according to EU guidelines. A dose comparison was made with an older PCR system (storage phosphor plates). With decreasing tube current the noise in the images increased and the image with the lowest dose and still acceptable image quality was identified. The results showed that the entrance surface dose using the DDD decreased from 1.4 mGy (PCR value) to 0.48 mGy (DDD standard settings). Through the optimisation the dose could be further decreased to 0.24 mGy while still maintaining an acceptable image quality. A substantial dose reduction was obtained with this new direct digital detector. This simple but efficient optimisation approach is easily applicable to other examinations and both DDD and storage phosphor plate detectors.

Image quality vs. radiation dose for a flat-panel amorphous silicon detector: a phantom study.

The aim of this study was to investigate the image quality for a flat-panel amorphous silicon detector at various radiation dose settings and to compare the results with storage phosphor plates and a screen-film system. A CDRAD 2.0 contrast-detail phantom was imaged with a flat-panel detector (Philips Medical Systems, Eindhoven, The Netherlands) at three different dose levels with settings for intravenous urography. The same phantom was imaged with storage phosphor plates at a simulated system speed of 200 and a screen-film system with a system speed of 160. Entrance surface doses were recorded for all images. At each setting, three images were read by four independent observers. The flat-panel detector had equal image quality at less than half the radiation dose compared with storage phosphor plates. The difference was even larger when compared with film with the flat-panel detector having equal image quality at approximately one-fifth the dose. The flat-panel detector has a very favourable combination of image quality vs radiation dose compared with storage phosphor plates and screen film.

Nationwide standardisation and evaluation of scintigraphic gastric emptying: reference values and comparisons between subgroups in a multicentre trial.

By means of a standardised procedure, reference values for scintigraphic gastric emptying were established. The influence of gender, age, menstrual cycle, body mass index (BMI) and smoking habits was also evaluated. Eight centres recruited 20 healthy subjects each. The meal consisted of a technetium-99m labelled omelet (1,300 kJ) and of 150 ml unlabelled soft drink. Geometric means of frontal and dorsal acquisitions were utilised in a linear fit model for determination of the linear emptying rate, and by using the intercepts of the regression line with the 90% and 50% levels, the lag phase and half-emptying time, respectively, were defined. All individuals showed an initial lag phase and subsequent linear emptying. Because of a longer lag phase and a slower linear emptying rate, premenopausal women had a slower gastric emptying than postmenopausal women and men of all ages. The gastric emptying rate increased with age in the women, mainly due to a shortened lag phase, while the emptying rate remained almost unchanged with age in the males. There were no significant differences in results between the centres. The menstrual cycle, BMI and smoking habits did not affect emptying. In conclusion, the fact that the results showed a slower gastric emptying rate in younger women compared with older women and men indicates that it is necessary to use separate reference values for fertile females.

[Examination of gastric emptying with gamma camera. Clinically useful, uniform method now established]. / Undersökning av ventrikeltömning med gammakamera. Kliniskt användbar, enhetlig metod nu fastställd.

Although more than 30 years have passed since the introduction of scintigraphic testing of gastric emptying there has been no well-defined standard. Eight Swedish hospitals have established a nationally standardized method for scintigraphic testing of gastric emptying of solids. 160 healthy subjects participated. The meal consisted of a 99mTc-labeled omelet (1300 kJ) and 150 ml unlabeled soft drink (290 kJ). There were no differences in calculated variables between the centers. Premenopausal women showed slower emptying than postmenopausals and men of any age, making separate reference values for younger women necessary.

Hypoglycaemia increases the gastric emptying rate in patients with type 1 diabetes mellitus.

The effect of insulin-induced hypoglycaemia on the gastric emptying rate was studied in eight patients with Type 1 diabetes mellitus of short duration (1-5 years). Gastric emptying was studied using a scintigraphic technique. All patients were studied twice, both during euglycaemia and insulin-induced hypoglycaemia. The blood glucose concentration was adjusted with an insulin-glucose clamp technique. All patients were examined in a standardized way, undergoing the first examination during euglycaemia, with a blood glucose concentration of 4-7 mmol l-1, and the second during hypoglycaemia, with a mean blood glucose concentration of 1.9 +/- 0.3 mmol l-1 at the time of starting the gastric emptying study. During hypoglycaemia both the liquid and the solid gastric emptying rates were significantly increased compared to the rate during euglycaemia. The time to empty 50% of the radioactivity from the stomach for liquid was 48.5 +/- 9.8 min during euglycaemia, compared to 27.6 +/- 20.2 min during hypoglycaemia, p < 0.001. The time to empty 50% of the radioactivity from the stomach for solid food was 48.7 +/- 10.3 min and 23.2 +/- 15.9 min, respectively, p < 0.001. In conclusion, it appears that insulin-induced hypoglycaemia increases the gastric emptying rate in patients with Type 1 diabetes mellitus.

Clinical evaluation with long-term follow-up of flutamide and estramustine as initial treatment of metastatic carcinoma of the prostate.

Thirty patients with metastatic cancers but with no serious cardiovascular (CV) conditions were randomly assigned to receive treatment either with flutamide (250 mg x 3) (F) or with estramustine (280 mg x 2) (E). Clinical examination, bone scan, laboratory measurements were performed before randomization and at regular intervals thereafter. During an observation period of between 1 and 2.5 years, F was discontinued in one case (7%) because of icterus, and E in three cases (20%) because of CV complications. Of the remaining 14 F-treated patients, 13 responded initially. Eleven of them relapsed, and five died of cancer. In the corresponding group of 12 E-treated patients, there were 11 primary responders. Of these, only two relapsed and died, as did the only nonresponder. The difference between the two groups with regard to relapse is significant (p less than 0.01), but not with regard to mortality. In the present material, there was an initial favorable response to F without signs of CV complications and with maintained libido in most cases. However, due to the significantly increased risk for relapse compared with E, F cannot be recommended as single therapy except in cases where estrogens are contraindicated or when interference with libido and potency is unacceptable.

Gastric emptying rate after gastric bypass and gastroplasty.

Fifty-seven morbidly obese patients were randomized into two surgical treatment groups, gastric bypass (n = 29) and gastroplasty (n = 28). Studies of the gastric emptying with radionuclide-labelled food were performed preoperatively (12 patients) and postoperatively at 2 months (28 patients) and 12 months (49 patients). Pouch emptying after gastric bypass was slower at 2 months than at 12 months. After gastroplasty the emptying rate was the same at 2 and 12 months and the same as that of gastric bypass at 12 months. A statistically significant correlation between stoma diameter and emptying rate was seen 1 year after gastroplasty but not after gastric bypass. No correlation between emptying rate and weight loss was shown in either group. Differences in the mechanisms of action between these two methods are apparent and are discussed.

Clinical evaluation of flutamide and estramustine as initial treatment of metastatic carcinoma of prostate.

The efficacy and side effects of flutamide were compared with estramustine in patients with advanced prostatic carcinoma. Thirty patients with metastatic cancers but with no serious cardiovascular (CV) conditions were randomly assigned to receive treatment either with flutamide (250 mg X 3) or with estramustine (280 mg X 2). Clinical examination, bone scan, laboratory measurements, including coagulation studies were performed prior to randomization, every three months during year one, and at six-month intervals thereafter. The two groups were comparable with respect to age and tumor characteristics. However, more patients presented with skeletal pain among those later treated with flutamide. During an observation period of between one and two and one-half years, flutamide was discontinued in 1 case (7%) because of icterus, and estramustine in 3 cases (20%) because of CV complications. Of the remaining 14 flutamide-treated patients, 13 responded initially. Eleven of them relapsed, and 5 died of cancer. In the corresponding group of 12 estramustine-treated patients, there were 11 primary responders. Of these, only 2 relapsed and died as did the only nonresponder. The difference between the two groups with regard to relapse is significant (P less than 0.01), but not with regard to mortality. All estramustine-treated patients lost their libido, whereas only 20 per cent of the patients treated with flutamide did so. In the present limited material there was an initial favorable response to flutamide without signs of CV complications and with maintained libido in most cases. However, due to significantly increased risk for relapse compared with estramustine, flutamide cannot be recommended as single therapy except in cases where estrogens are contraindicated or when interference with libido and potency is unacceptable.

Serial bone scanning in the evaluation of stage and clinical course in carcinoma of the prostate.

Bone scanning with 99mTc-EHDP or 99mTc-MDP was compared with skeletal X-ray survey, determination of acid phosphatase levels and clinical symptoms in a consecutive series of 176 patients with prostatic carcinoma. Skeletal metastases were present in 24%. In these metastatic cases 27% had negative radiographics at the time of initial diagnosis, 29% had normal serum acid phosphatase values and 74% had symptoms other than skeletal, which dominated the clinical picture. When bone scanning was negative for metastases such lesions were never detected in the radiographs. Hence, bone scanning was sufficient for the initial diagnosis of skeletal metastases in 55% of cases. When scans were judged as equivocal or positive an X-ray survey should be done. The variations in count density in metastatic disease were followed by visual assessment of serial bone scans. A densitometric method for quantification of the variations was developed as an aid in the evaluation. Serial bone scanning using a quantitative method appears to offer a readily available objective index of early therapeutic response for use in general clinical practice as well as in controlled therapeutic trails.

The value of whole body bone scan in the pre-operative assessment in carcinoma of the breast.

In 126 patients with primary breast cancer a patient moving whole body bone scan was performed when they first presented. None of the patients in stage I had an evidence of skeletal metastases. Two patients (3%) of 62 in stage II and 4 patients (17%) in stage III had evidence of skeletal metastases. It appears that whole body scanning is the most accurate, sensitive and convenient method of detecting osseous metastases and of staging breast cancer. This investigation should be carried out pre-operatively. Detection of early asymptomatic bony metastases will provide a better planning of treatment with rational approach.