SPIRAL CT ANGIOGRAPHY OF MIDDLE CEREBRAL- ARTERY STENOSES

Introduction: Transcranial Doppler ultrasonography (TCD) and magnetic resonance angiography (MRA) are well-established techniques for ascert aining intracranial obstructive artery disease. The short examination time required for additional helical CT angiography (CTA) allows quick management of emergency patients already undergoing native CT. Howeve r, today the ability of CTA to detect stenoses of the middle cerebral artery (MCA) has not been proven. To analyse the value of CTA in the c lassification of atherosclerotic disease 23 MCA stenoses confirmed by TCD and MRA were investigated. Methods: CTA was performed on a Hispeed advantage scanner (GE) using a bolus injection of 70 ml KM and 40 mi NaCl with a Row rate of 2.5 ml/s, a thickness of 1 mm, a pitch of 1.5 and a 1 mm increment. CTA was presented as maximum intensity projectio n (MIP) and as multi-projection volume reconstruction (MPVR). A three- step classification of stenosis was compared with the results of TCD a nd MRA. Results: Good opacification of the MCA was achieved in MI and M2 segments in all patients. Classification of stenosis by CTA agreed with MRA and TCD in 14 cases: 7 stenoses were assigned to a lower clas sification by CTA. Two low-grade stenoses could not be proven by CTA, Although MIP and MPVR yield the same result in stenosis classification MPVR showed a sharper image quality. In contrast to MRA, veins were h ighly opacified in CTA, Artery and vein were sometimes superimposed, w hich had to be avoided by changing the projection angle. Conclusion: M edium- and high-grade MCA stenoses can be demonstrated by CTA quickly and reliably. Compared to MRA and TCD, CTA provides lower grading of s tenosis.