The Yield of Computerized Tomography, Perfusion Computerized Tomography and Diffusion-Weighted Magnetic Resonance Image in Patients Presenting with Transient Ischemic Attack and Acute Ischaemic Stroke

Background: A transient ischaemic attack (TIA) or acute ischaemic stroke (AIS) with transient symptoms can presage a debilitating acute ischaemic stroke and some stroke mimics can have undesired consequences if not diagnosed and treated promptly. The use of computerized tomography (CT), perfusion computerised tomography (P-CT) and diffusion weighted magnetic resonance imaging (DW-MRI) is critical in facilitating early diagnosis and subsequent management of patients with acute focal neurological dysfunctions. Aim: This study investigated the yield of computerised tomography (CT), Perfusion-CT(P-CT), and Diffusion weighted-MRI(DW-MRI) scans in patients Diagnosed with TIA and AIS. Methodology: This is a retrospective cohort study of 162 cases of TIA (55%) and acute ischaemic stroke (AIS), who presented to Goulburn Valley Hospital in Shepparton from January to December 2021. Microsoft EXCEL software was used for statistical analysis. The chi-square test with Yates' correction was used to compare propositions, and a p-value of < 0.05 is considered statistically significant. Results: The male to female ratio was 1.5 to 1, with a mean age of 74 years. The initial CT brain was normal in all 89 TIA patients, while 69.8% of the 63 AIS patients had infarct. 95% of AIS (n=41) patients had perfusion abnormalities on P-CT compared to only 17% of TIA patients (n=71) (P<0.00001). Similarly, 94% of AIS (n=35) compared to 18% of TIA (n=55) patients had diffusion weighted abnormality on DW-MRI (p<0.00001).13.5% of the TIA case(n=5) and 100% of the AIS(n=5) with normal CT and P-CT had diffusion abnormality on DW-MRI. Among the 4 TIA cases that had DW-MRI after normal CT and positive P-CT only 20% (n=1) showed diffusion abnormality. On CT carotid and cerebral angiograms, 49% of TIA (n=37) compared to 76% of AIS (n=55) patients had significant stenosis of over 50% (p<0.01). Conclusion: Normal initial CT brain is a valuable initial test for differentiating TIA from AIS in patients with acute focal neurologic dysfunctions. The addition of P-CT and DW-MRI imaging demonstrated abnormalities in most of those with AIS when compared with those with TIA. Although a small percentage of those with TIA had abnormalities on P-CT and DW-MRI these two modalities add value to investigation of TIA. Therefore, the use of P-CT and DW-MRI are pertinent when the initial CT brain is normal as they are more sensitive in demonstrating abnormalities than plain CT.