Publishing type：Research paper (scientific journal)   Publisher：Ovid Technologies (Wolters Kluwer Health)  

Abstract

BACKGROUND

The hemodynamic changes after superficial temporal artery (STA) to middle cerebral artery (MCA) bypass surgery are unclear.

OBJECTIVE

To clarify the hemodynamics by comparing flow parameters obtained by 4-dimensional (4D) flow magnetic resonance imaging (MRI) and intraoperative MCA pressure measurement.

METHODS

We recruited 23 patients who underwent STA-MCA bypass surgery for internal carotid artery (ICA) or MCA stenosis. We monitored intraoperative MCA, STA, and radial artery (RA) pressure. All patients underwent 4D flow MRI preoperatively and 3 wk after surgery to quantify the blood flow volume (BFV) of the ipsilateral ICA (BFV_iICA), contralateral ICA (BFV_cICA), basilar artery (BFV_BA), ipsilateral STA (BFV_iSTA), and contralateral STA (BFV_cSTA). The sum of intracranial BFV was defined as BFV_total. We compared BFV parameters and intraoperative pressure.

RESULTS

BFV_iSTA significantly increased after surgery (P < .001). BFV_iICA and BFV_BA significantly decreased after surgery (BFV_iICA P = .005; BFV_BA P = .02). No significant difference was observed between BFV_cICA before and after surgery. As a result, BFV_total postoperatively increased by 6.8%; however, no significant difference was observed. Flow direction at M1 changed from antegrade to unclear after surgery in 5 patients. Intraoperative MCA pressure and MCA/RA pressure ratio significantly increased after surgery (P < .001). We found a stronger positive correlation between MCA pressure increase ratio and BFV_total increase ratio in patients with lower pre-MCA pressure (r = 0.907, P < .001).

CONCLUSION

The visual and quantitative assessment of 4D flow MRI revealed that intracranial blood flow changes complementarily after STA-MCA bypass surgery. 4D flow MRI may detect the improvement of cerebral perfusion pressure.

DOI： 10.1093/neuros/nyab305

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Other Link： https://journals.lww.com/10.1093/neuros/nyab305

Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

Aim

Attenuation correction using zero-echo time (ZTE) – magnetic resonance imaging (MRI) (ZTE-MRAC) has become one of the standard methods for brain-positron emission tomography (PET) on commercial PET/MR scanners. Although the accuracy of the net tracer-uptake quantification based on ZTE-MRAC has been validated, that of the diagnosis for dementia has not yet been clarified, especially in terms of automated statistical analysis. The aim of this study was to clarify the impact of ZTE-MRAC on the diagnosis of Alzheimer’s disease (AD) by performing simulation study.

Methods

We recruited 27 subjects, who underwent both PET/computed tomography (CT) and PET/MR (GE SIGNA) examinations. Additionally, we extracted 107 subjects from the Alzheimer Disease Neuroimaging Initiative (ADNI) dataset. From the PET raw data acquired on PET/MR, three FDG-PET series were generated, using two vendor-provided MRAC methods (ZTE and Atlas) and CT-based AC. Following spatial normalization to Montreal Neurological Institute (MNI) space, we calculated each patient’s specific error maps, which correspond to the difference between the PET image corrected using the CTAC method and the PET images corrected using the MRAC methods. To simulate PET maps as if ADNI data had been corrected using MRAC methods, we multiplied each of these 27 error maps with each of the 107 ADNI cases in MNI space. To evaluate the probability of AD in each resulting image, we calculated a cumulative t-value using a fully automated method which had been validated not only in the original ADNI dataset but several multi-center studies. In the method, PET score = 1 is the 95% prediction limit of AD. PET score and diagnostic accuracy for the discrimination of AD were evaluated in simulated images using the original ADNI dataset as reference.

Results

Positron emission tomography score was slightly underestimated both in ZTE and Atlas group compared with reference CTAC (−0.0796 ± 0.0938 vs. −0.0784 ± 0.1724). The absolute error of PET score was lower in ZTE than Atlas group (0.098 ± 0.075 vs. 0.145 ± 0.122, p < 0.001). A higher correlation to the original PET score was observed in ZTE vs. Atlas group (R²: 0.982 vs. 0.961). The accuracy for the discrimination of AD patients from normal control was maintained in ZTE and Atlas compared to CTAC (ZTE vs. Atlas. vs. original; 82.5% vs. 82.1% vs. 83.2% (CI 81.8–84.5%), respectively).

Conclusion

For FDG-PET images on PET/MR, attenuation correction using ZTE-MRI had superior accuracy to an atlas-based method in classification for dementia. ZTE maintains the diagnostic accuracy for AD.

DOI： 10.3389/fnins.2020.569706

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Publishing type：Research paper (scientific journal)  

DOI： 10.1148/rg.2020200177

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1007/s00234-020-02464-2

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Other Link： https://link.springer.com/article/10.1007/s00234-020-02464-2/fulltext.html

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: There is increasing evidence that a proportion of patients with cardiac sarcoidosis (CS) have atrial arrhythmias (AA). Although 18F-fluorodeoxy-glucose (FDG) uptake in the ventricle on positron emission tomography/computed tomography (PET/CT) is well studied, FDG uptake in the atrium has not been elucidated in detail. OBJECTIVES: To evaluate FDG uptake in the atrium and its relationship with AA in patients with CS. METHODS: We retrospectively investigated 62 CS patients. All patients underwent echocardiography and PET/CT. Serum angiotensin converting enzyme (ACE) and soluble IL-2 receptor (sIL-2R) levels, plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) concentrations were also evaluated. ECG, Holter monitoring and device interrogations were used to detect AA. RESULTS: Of the studied population, 25 patients (40.3%) had AA, of which 2 patients had atrial tachycardia (AT) and 23 patients had atrial fibrillation (AF). Eighteen patients with AA had atrial FDG uptake on PET/CT, whereas 14 patients without AA had atrial FDG uptake (72.0% vs 37.8%, P = 0.017). Multivariate analysis revealed a significant association between AA and age (odds ratio [OR]: 1.15; 95% confidence interval [CI]: 1.01-1.31, P = 0.040), atrial FDG uptake (odds ratio [OR]: 7.23; 95% confidence interval [CI]: 1.91-27.36, P = 0.004), and left atrial diameter (OR: 1.08; 95% CI: 1.01-1.16, P = 0.027). Meanwhile, gender, serum ACE and BNP levels, and left ventricular ejection fraction were not associated with AA. CONCLUSIONS: Atrial FDG uptake was common in patients with CS and strongly associated with AA.

DOI： 10.1016/j.ijcard.2020.04.041

PubMed

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Language：Japanese   Publisher：(一社)日本磁気共鳴医学会  

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Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2020&ichushi_jid=J02090&link_issn=&doc_id=20200319090009&doc_link_id=10.2463%2Fjjmrm.2019-1700&url=https%3A%2F%2Fdoi.org%2F10.2463%2Fjjmrm.2019-1700&type=J-STAGE&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00007_3.gif

Language：English   Publisher：(公社)日本医学放射線学会  

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Publishing type：Research paper (scientific journal)   Publisher：Ovid Technologies (Wolters Kluwer Health)  

Abstract

BACKGROUND

The hemodynamic changes that occur after high-flow (extracranial–intracranial) EC-IC bypass surgery with internal carotid artery (ICA) ligation are not well known.

OBJECTIVE

To assess blood flow changes after high-flow EC-IC bypass with ICA ligation by time-resolved 3-dimensional phase-contrast (4D Flow) magnetic resonance imaging (MRI).

METHODS

We enrolled 11 patients who underwent high-flow EC-IC bypass. 4D Flow MRI was performed before and after surgery to quantify the blood flow volume (BFV) of the ipsilateral ICA (BFV_iICA), bypass artery (BFV_bypass), contralateral ICA (BFV_cICA), and basilar artery (BFV_BA). Subsequently, we calculated the total BFV (BFV_total = BFV_iICA + BFV_cICA + BFV_BA [before surgery], BFV_cICA + BFV_BA + BFV_bypass [after surgery]). The BFV changes after bypass was statistically analyzed.

RESULTS

BFV_bypass was slightly lower than BFV_iICA, but the difference was not statistically significant (3.84 ± 0.94 vs 4.42 ± 1.38 mL/s). The BFV_cICA and BFV_BA significantly increased after bypass surgery (BFV_cICA 5.89 ± 1.44 vs 7.22 ± 1.37 mL/s [P = .0018], BFV_BA 3.06 ± 0.41 vs 4.12 ± 0.38 mL/s [P < .001]). The BFV_total significantly increased after surgery (13.37 ± 2.58 vs 15.18 ± 1.77 mL/s [P = .015]). There was no evidence of hyperperfusion syndrome in any cases.

CONCLUSION

After high-flow EC-IC bypass with permanent ICA ligation, the bypass artery could partially compensate for the loss of BFV of the sacrificed ICA. The increased flow of the contralateral ICA and BA supply collateral blood flow. Clinically irrelevant hyperperfusion was observed.

DOI： 10.1093/neuros/nyy192

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