Effectiveness of Gatekeepers in Determining the Appropriate Use of Brain MRI/MRA Tests

Table 1

Criteria for defining the case group and control group.

		Diagnostic names of medical care information system (major complaints in undergoing tests)	Diagnostic names obtained from the results of radiogram interpretations
Case group (𝑛=156)	Criteria of case 1	(i) Headaches; (ii) Dizziness; (iii) Staggering; (iv) Fainting; (v) Temporary consciousness disorder; (vi) Hyposthenia, palsy, dysmobility; (vii) Peripheral nerve symptoms; (viii) Brain tumors, possible brain tumors; (ix) Cerebrovascular damage, possible cerebrovascular damage	Patients who were diagnosed as having brain tumors in the results of interpretations of radiograms of head MRI tests.
	Criteria of case 2		Patients who had clinically significant cerebrovascular damage (stenosis and cerebral stroke) identified in the results of interpretations of radiograms of head MRA or MRI tests^Note 1,2.
Control group; (𝑛=721)	Criteria of control	Applying to any of the above names (more than one item can be selected)	Patients who did not show clinically significant abnormalities upon head MRI or head MRA tests.

Note 1: definition of clinically significant cerebrovascular stenosis.
Stenosis in 50% of the internal carotid artery, common carotid artery, forebrain/midbrain/hindbrain artery, vertebral artery, and basilar artery.
Note 2: definition of clinically significant cerebral stroke.
(i) Findings of brain infarction on images that clearly explain symptoms in the medical records.
(ii) Findings of brain infarction in diffusion MRI.
(iii) Findings of brain hemorrhaging determined to be within four weeks after onset.