COMPUTERISED AXIAL TOMOGRAPHY: EQUIPMENTS AND USE IN THE ACBC. INSTRUCTIONS ON THE APPROPRIATE USE OF CAT

INTRODUCTION

Today, together with magnetic resonance imaging, computerised axial tomography (CAT) is one of the so-called "high technology" imaging diagnosis procedures.

Over the last ten years there has be en an increase in the number of CAT units in health centres in the Autonomous Community of the Basque Country (ACBC). The first CAT unit was installed in 1978 and currently there are 25 units in operation.

Osatek/Tecnología Sanitaria de Euskadi/s.a. And the Health Department have carried out an analysis of the availability and current use of CAT systems in centres included within the Basque health service network. Likewise, recommendations have been drawn up regarding the use and appropriate prescription of the diagnostic tests made with CAT, based on the best scientific evidence available.

AIMS OF THE STUDY

  1. Determine the characteristics and use of existing CAT apparatus and equipment in the Basque health service.
  2. Summarise data relating to surveys carried out to analyse the reliability of CAT exploration in the diagnosis and treatment of different pathologies.
  3. Draft recommendations on the use of this image technology in accordance with its suitability. These recommendations are classified in three categories.

MATERIAL AND METHODS

Information on the characteristics of CAT units, by means of a questionnaire sent to all public and private health centres that have CAT units in this community.

Information on the use of TAC equipment between 1996 and 1999.

Systematic review of the scientific literature on this subject by selecting surveys, clinical practice guidelines and standards concerning the recommendations for use of CAT units, published in medical and scientific reviews of proven quality.

RESULTS

Currently, there are a total of 25 units operating in the ACBC of which 60% are installed in Osakidetza/SVS hospitals. The average age of the CAT units presently in use is six years.

In 1999, the number of CAT units in the ACBC was 11.9 CAT units per million inhabitants, a figure which is a little under the average according to data available from neighbouring countries.

The distribution of equipment according to the three provinces that form the Basque Country is 17.8 in Gipuzkoa (48%), 10.6 in Araba and 0.8 in Bizkaia. In Gipuzkoa, there is the same number of apparatus in public and health centres. On the other hand, in Bizkaia and Araba, two thirds of the apparatus are installed in public health centres.

In 1996, more than 92,000 explorations were made with CAT units in all 24 health centres existing in this community.

In 1998, and taking into consideration only those centres on which we have up-to-date information, the increase with regard to 1997 was 8% in public centres and 18% in private ones. The 22% increase in activity of Cruces Hospital should be highlighted.

The percentage of activity corresponding to private centres is maintained at about 20% throughout the period under study, except in the case of Araba which represents about 6% of the total activity.

When we analyse the number of explorations for every 100 inhabitants, variations can be seen between the three Historic Territories. Thus, in 1996, 40 explorations/1000 inhabitants were made in Araba, compared to more than 67 and 33 in Bizkaia and Gipuzkoa respectively. 1997 shows the aforementioned increase, having made a total of 48 explorations for every 10000 inhabitants in Araba, more than 70 in Bizkaia and more than 33 in Gipuzkoa. During 1998 and 1999, the number of explorations in Araba was similar (48 and 51/1000 inhabitants) while in Bizkaia this increased to more than 90 in 1998 and more than 86 in 1999.

89.5% of explorations are made in hospitalised patients, 20% in ambulatory patients and 10.5% of requests come from Medical-Surgical Emergency Services.

More than 43% of the explorations performed correspond to brain/cranium explorations, only 14.6% to the abdomen, 11% cover more than one area, such as the thorax, abdomen and/or pelvis. The thorax represents 7% and explorations of the vertebral column represent 6%.

According to afea, neurologists and neurosurgeons are responsible for 14% of the requests. Oncologists represent 12.5% of the total number of explorations.

CONCLUSIONS

  1. The number of CAT units per million inhabitants in operation in the ACBC coincides within the values for countries with a similar socio-economic level.
    With regard to distribution, we observe that almost half of the CAT units installed in the ACBC are in Gipuzkoa, whose population represents only a third of the total for the Basque Country. In this province, there are a high number of CAT units in the private sector.
    The average age of units in operation is around six years, but six of those belong to the public sector and tour of the units installed in private centres have been in operation for almost ten years or more.
  2. With regard to sources of information concerning the activities performed by CAT units, it should be pointed out that:
  3. With regard to the scientific evidence on the effectiveness of CAT explorations, we should point out that the scientific literature on the subject provides only a few surveys that assess the final impact on the health of patients subjected to a CAT or other kind of exploration. In addition to the lack of sound scientific evidence there is also the problem of not knowing to what extent the results of existing surveys can be extrapolated to our environment. In some cases, CAT explorations may not lead to a diagnosis different from other diagnostic techniques, but its aspects, the overall information relating to a process, information on the treatment, development or the associated pathology, may vary quantitatively or qualitatively. Moreover, CAT explorations reduce the diagnosis time and may cause a modification of the decision prior to treatment in 50% of cases.
  4. With regard to instructions on the appropriate use of CAT, this is a technique chosen for the diagnosis of lesions of bone structures, without forgetting its role prior to convencional radiographic exploration.
    There is certain evidence of the usefulness of computerised tomography as a diagnostic proof of cerebral traumatism and in cases of suspected intracranial haemorrhage.
    Likewise, in thoracic and abdominal pathology, scientific evidence suggests that CAT explorations are used almost always as a complementary technique.