Radiology in the Nordic Countries.

NEMT, Nordic Evaluation of Medical Technology, conducted a study in 1988-89 on the use and diffusion of diagnostic radiology technologies in Denmark, Finland, Iceland, Norway and Sweden, i.e. the Nordic Countries. The study analysed the responses to a questionnaire sent to all Nordic radiology departments. Our findings show a variation from about 500 to nearly 900 radiology examinations per 1000 inhabitants among the Nordic Countries. Some of the differences are explained by unique structural factors of the health care system in each country, even if they all provide comparable public health services. Other differences are explained by variations in medical practice, accessibility to new imaging modalities, and replacement policies. This paper summarizes the results of the study.

Digital radiography of the spine, large bones and joints using stimulable phosphor. Early clinical experience.

The value of digital radiography in musculoskeletal disorders was investigated by assessing its ability to depict anatomic structures and common radiologic features as compared with the conventional film-screen combination. The digital image that was frequency modified was superior to conventional films in delineating soft tissue structures and for areas with large attenuation differences. The conventional film-screen system was superior in depicting small anatomic structures and in identifying the zone close to prostheses. This was explained by the high spatial resolution of the conventional film system and the disturbing halo effect around the prosthesis seen with digital images. The halo effect is an overshoot caused by the unsharp masking operator, which was in this series not changed for individual examinations. The exposure (radiation dose) could be reduced to 50 per cent using the digital system, without any loss of information.

Digital urography using stimulable phosphor. An experimental study in the rabbit.

In a urographic experimental study in six rabbits conventional film-screen images were compared with digitized images. Two digitized images were examined, one simulating the conventional film-screen combination, and one frequency modified. The nephrographic and excretory phases of four different doses of contrast medium (iohexol, 350 mg I/ml) were investigated in each rabbit (4, 2, 1, and 0.5 ml/kg body weight). No differences were found between the different doses of contrast medium for the two imaging systems. With digitized images the exposure (radiation dose) could be decreased to 12.5 per cent of the conventional film-screen combination without any loss of information.

Digital radiography using laser stimulated luminescence for evaluation of urinary calcifications.

One hundred consecutive patients were investigated with both a conventional film-screen combination and digital radiography using a laser stimulated luminescence technique in order to evaluate differences in detecting urinary tract stones. All patients were referred either for follow-up of previously known stones or for symptoms. The images were reviewed by two radiologists who had the single clinical information that the patients might have urinary stones. Following review, the two techniques were compared and a consensus was obtained. One hundred and eighteen stones were found in 41 patients without any statistical differences in sensitivity between the two imaging systems.

Hepatic ultrasonography in the terminally ill patient.

In 53 patients comparison was made between findings at autopsy and findings at ultrasound (US) examination performed shortly before death as the only morphologic diagnostic procedure of the liver during the patient's last year. US was found to be highly accurate. The non-invasiveness and the possibility of examining the patient in bed make US examination in experienced hands the ideal initial diagnostic procedure, especially in terminally ill patients.

Postmortem examination of the blood supply and vascular pattern of small liver metastases in man.

Thirteen human cadavers with liver metastases were examined. Microfil was injected into the portal vein and hepatic artery. The liver metastases were examined under dissecting microscope, and their vascular supply and patterns were registered. It was found that most metastases had both arterial and portal supply even if the arterial supply dominated. Extensive filling of tumor vessels was observed in both lobes in one liver in which the portal vein of one lobe and the hepatic artery of the other was injected (i.e., the same kind of metastases could be filled from either the hepatic artery or the portal vein). It is suggested that the findings could be of great importance in planning treatment of patients with liver metastases.

Microvasculature architecture of small liver metastases in man. A correlation between microfil vascular preparations and histologic sections.

The hepatic artery and the portal vein of 12 human cadaver livers with metastases of various sizes and origins were injected with Microfil. The microvascular appearances of the metastases were studied in order to receive an explanation to findings at angiography and contrast enhanced computed tomography. Histologic examinations were also performed of Microfil-injected specimens.

Occlusion of renal arterial tumor supply with absolute ethanol. Experience with 20 cases.

Absolute ethanol was used for renal ablation in 20 patients with carcinoma of the kidney. The procedure was followed by nephrectomy in 6 patients without metastases, all of whom are alive without evidence of recurrence 4 to 20 months after treatment. Fourteen patients with metastatic or locally advanced disease were embolized to palliate pain or hematuria without subsequent nephrectomy. Of these only 2 are alive, 4 and 18 months following the procedure. The technique for ethanol embolization is described and the use of occluding balloon catheters is recommended. No complications were encountered and the 'postembolization syndrome' was less marked as compared with a previous material of equal size where other methods of renal artery occlusion were employed. Microscopic examination in 10 of the infarcted kidneys showed extensive tumor necroses, sometimes with no evidence of viable tumor cells at all. Natural killer cell activity was determined before and 48 hours after renal artery occlusion in 7 patients, showing somewhat increased activity in 4. It is concluded that absolute ethanol is a safe, effective and easily administered agent for the infarction of renal tumors.

Lateral displacement of the right kidney by the ascending colon.

A case of lateral displacement of the lower pole of the right kidney caused by an interposing ascending colon is presented. An interposition of this kind is rare and does not cause any gastrointestinal symptoms but is of differential diagnostic importance. In this case computed tomography was a simple noninvasive procedure for correct diagnosis.

Selection of intravascular contrast media in clinical radiology.

From previous experimental investigations and from the present clinical experience in more than 2000 examinations it is clear that the adverse reactions of Omnipaque are markedly less when compared with those of conventional contrast media for intravascular use. Similar observations have been made for other low osmolar contrast media. These new media should therefore replace the conventional media for intravascular use. The economical consequences are discussed.

Desensitisation as a means of preventing untoward reactions to ionic contrast media.

Patients with a previous history of anaphylactic reactions to ionic iodinated contrast media were desensitised before a second radiologic examination was performed. The tolerance to the contrast medium was raised by repeated intravenous injections in increasing doses and concentrations. No serious side effects were noted when the examinations with contrast medium was repeated within a few days after the desensitisation. The positive effect of the desensitisation may depend on a successive consumption of complement proteins, probably responsible for the allergic reactions. Therefore, the available amount of complement for some days may be too low for the occurrence of a complement reaction.

Angiography in pancreatic disease reevaluated. A prospective and blind evaluation.

Eighty-six consecutive pancreatic angiographies were reviewed prospectively. Ater more than one year 79 of them were "blindly" and independently reviewed by three radiologists. The results concerning accuracy, value three radiologists. The results concerning accuracy, value of superselective technique at malignancy and prediction of extirpability at malignancy were compared. The accuracy was similar, i.e. at malignancy 92 and 86 per cent (mean), respectively, as the prediction of extirpability 88 and 80 per cent (mean), respectively. The value of superselective technique differed considerably, 55 and 14 per cent (mean), respectively, and this is discussed. Pancreatic angiography in relation to CT, ultrasound and ERCP is discussed and considered to be of value late in the diagnostic program.

Abdominal angiography after intra-arterial injection of vasopressin.

Vasopressin administered as a bolus immediately before selective visceral angiography increased the information obtained in hepatic and pancreatic disease. The drug may be helpful in differentiating between inflammatory and malignant lesions in the intestines.