Purpose: To demonstrate the discrepancy of cerebral blood flow volume (BFV) estimation with 2D phase-contrast (2D PC) MRA guided with 3D time-of-flight (3D TOF) MR localization by using an "internal" standard. Materials and methods: 20 groups of the common (CCA), internal (ICA), and external (ECA) carotid arteries in 10 healthy subjects were examined with 2D PC MRA guided by 3D TOF MR angiograms. The sum BFV of the internal and external carotid arteries was then compared with the ipsilateral common carotid artery flow. An accurate technique would demonstrate no difference. The difference was therefore a measure of accuracy of the method. Results: 3D TOF MRA localization is presented to allow the determination of a slice orientation to improve the accuracy of 2D PC MRA in estimate the BFV. By using the combined protocols, there was better correlation in BFV estimate between the sum of ICA+ECA with the ipsilateral CCA (R 2 = 0.729, P = 0.000). The inconsistency (mean SD) was found to be 6.95 5.95% for estimate the BFV in ICA+ECA and ipsilateral CCA. The main inconsistency was contributed to the ECA and its branches. Conclusions: Guided with 3D TOF MRA localization, 2D PC MRA is more accurate in the determination of blood flow volume in the carotid arteries.
Purpose: The hyperintense appearance of the middle cerebral artery (HMCA) sign consists of a thickened MCA stem with a blurred intense signal on contrast enhanced T1-weighted magnetic resonance imaging (T1W MRI). In this article, we define it and determine its incidence, diagnostic value, and reliability by comparison with magnetic resonance angiography and digital subtraction angiography. Materials and Methods: Non-contrast CT and immediately subsequent MRI were performed on 30 consecutive patients with acute ischemic stroke within 6 hours after symptom onset. All patients underwent at least one follow-up MRI or non-contrast CT within 2-7 days. Initial studies were analyzed for HMCA sign on post-Gd T1WI. Vascular findings on both MRI and CT were compared with findings at MRA and DSA. Results: Eleven patients were developed subsequent HT at follow-up studies. The HMCA sign on MRI was found in 6 hemorrhagic patients (P =0.00), and all of them had M1 occlusion on angiography. None of the patients in nonhemorrhagic group had HMCA sign on MRI. Conclusion: HMCA sign on post-Gd T1WI is highly specific and moderately sensitive indicator of acute thrombus with M1 MCA segment, as validated by angiography. Additionally, HMCA sign may be a useful marker of subsequent HT in acute ischemic stroke.
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