Improved cerebral blood flow and hippocampal blood flow in stroke-free patients after catheter ablation of atrial fibrillation.

INTRODUCTION: Atrial fibrillation (AF) is a risk factor for reduced cerebral blood flow (CBF) and cognitive dysfunction, even in stroke-free patients. We aimed to test the hypothesis that CBF and hippocampal blood flow (HBF), measured with arterial spin labeling magnetic resonance imaging (MRI), improve after catheter ablation of AF to achieve sinus rhythm (SR). METHODS: A total of 84 stroke-free patients (63.1 ± 9.1 years; paroxysmal AF, n = 50; non-paroxysmal AF, n = 34) undergoing AF catheter ablation were included. MRI studies were done before, 3 months, and 12 months after the procedure with CBF and HBF measurements. RESULTS: Baseline CBF and HBF values in 50 paroxysmal AF patients were used as controls. Baseline CBF was higher in patients with paroxysmal AF than with non-paroxysmal AF (100 ± 32% vs. 86 ± 28%, p = .04). Patients with non-paroxysmal AF had increased CBF 3 months after AF ablation (86 ± 28% to 99 ± 34%, p = .03). Differences in CBF and HBF were greater in the group with AF restored to SR (p < .01). Both CBF and HBF levels at 12 months were unchanged from the 3 months level. Successful rhythm control by catheter ablation was an independent predictor of an increase in CBF > 17.5%. The Mini-Mental State Examination score improved after ablation (p = .02). CONCLUSION: SR restoration with catheter ablation was associated with improved CBF and HBF at 3 months, maintenance of blood flow, and improved cognitive function at 12 months.

Effect of cerebrospinal fluid area mask correction on 123I-FP-CIT SPECT images in idiopathic normal pressure hydrocephalus.

BACKGROUND: Cerebrospinal fluid (CSF) area mask correction reduces the influence of low [123I]-N-fluoropropyl-2b-carbomethoxy-3b-(4-iodophenyl) nortropane (123I-FP-CIT) accumulation in the volume of interest (VOI) by CSF area dilatation on the specific binding ratio (SBR) calculated using the Southampton method. We assessed the effect of CSF area mask correction on the SBR for idiopathic normal pressure hydrocephalus (iNPH) characterized by CSF area dilatation. METHODS: We enrolled 25 patients with iNPH who were assessed using 123I-FP-CIT single-photon emission computed tomography (SPECT) before shunt surgery or the tap test. The SBRs with and without CSF area mask correction were calculated, and changes in quantitative values were verified. Additionally, the number of voxels in the striatal and background (BG) VOI before and after CSF area mask correction were extracted. The number of voxels after correction was subtracted from that before correction, and the volume removed by the CSF area mask correction was calculated. The volumes removed from each VOI were compared to verify their effect on SBR. RESULTS: The images of 20 and 5 patients with SBRs that were decreased and increased, respectively, by CSF area mask correction showed that the volumes removed from the BG region VOI were higher and lower, respectively than those in the striatal region. CONCLUSIONS: The SBR before and after CSF area mask correction was associated with the ratio of the volume removed from the striatal and BG VOIs, and the SBR was high or low according to the ratio. The results suggest that CSF area mask correction is effective in patients with iNPH. TRIAL REGISTRATION: This study was registered in the UMIN Clinical Trials Registry (UMIN-CTR) as UMIN study ID: UMIN000044826. 11/07/2021.

Comparison of the decreases in regional cerebral blood flow in the posterior cingulate cortex, precuneus, and parietal lobe between suspected non-Alzheimer's disease pathophysiology and Alzheimer's disease.

BACKGROUND: Suspected non-Alzheimer's disease pathophysiology (SNAP) shows Alzheimer's disease (AD)-like neurodegeneration; however, amyloid ß, which is a biological marker in AD, remains within normal levels. Since the effectiveness of anti-dementia drugs for AD on SNAP is unknown, it is important to distinguish between patients with SNAP and AD. We aimed to compare decreases in regional cerebral blood flow (rCBF) of the posterior cingulate cortex (PCC), precuneus, and parietal lobe critical to AD between SNAP and AD groups using the easy Z-score imaging system in single-photon emission computed tomography (eZIS-SPECT). METHODS: We retrospectively analysed eZIS-SPECT data of 13 SNAP and 24 AD patients. The three indicators (severity, extent, and ratio) that distinguished AD patients from healthy controls in previous studies were automatically calculated and were compared between the SNAP and AD groups. Receiver operating characteristic curve analysis and the area under the curve (AUC) were used to evaluate the diagnostic performance of the three indicators of eZIS in discriminating between the two groups. RESULTS: The mean values of severity, extent, and ratio were significantly lower in the SNAP group than in the AD group (P = 0.024, P = 0.044, and P = 0.045, respectively). The AUC values for severity, extent, and ratio were 0.668, 0.683, and 0.692, respectively. CONCLUSIONS: The present study suggests that SNAP shows milder reduction of rCBF in the PCC, precuneus, and parietal lobe as compared to AD. However, it may be difficult to distinguish between SNAP and AD with the degrees of decrease in rCBF in these regions.

Quantification of myocardial blood flow and myocardial flow reserve by 13N-NH3 PET/CT is not significantly affected by pixel size.

PURPOSE: Myocardial blood flow (MBF) and myocardial flow reserve (MFR) are measurable by 13N-NH3 positron emission tomography (PET). MFR, which is the ratio of MBF under adenosine stress to MBF at rest, is prognostically valuable. The ASNC imaging guidelines/SNMMI procedure standards recommend using 2-3 mm pixels, and pixel size does differ between institutions. We sought to evaluate the effects of pixel sizes on the quantitative values calculated from 13N-NH3 PET images. METHODS: Thirty consecutive patients with ischemic heart disease who underwent 13N-NH3 PET were retrospectively enrolled. Dynamic images were quantified using PMOD's cardiac PET analysis tool (pixel sizes: 3.18, 2.03, and 1.59 mm). MBF under adenosine stress, MBF at rest, and MFR for the right coronary artery (RCA) region, left anterior descending artery region, and left circumflex coronary artery branch region innervation regions were calculated at each pixel size and compared. RESULTS: Quantitative values did not significantly differ according to pixel size in any of the regions. However, MFR values for the RCA fluctuated the most. Ischemic and non-ischemic regions remained visually discernible in qualitative images, with no variation in quantitative values, regardless of pixel size. CONCLUSIONS: Quantitative values were not significantly affected by pixel sizes within the recommended range of 2-3 mm. Values for the RCA region may have been overestimated, but this was true for all pixel sizes.

A Headrest Made of Extruded Polystyrene Reduces the Influence of Attenuation Correction on Human Brain SPECT Images.

Previous reports suggest that a headrest made of carbon significantly influences cerebral blood flow in the anterior and posterior regions by image reconstruction and attenuation correction (AC). The present study aimed to develop a headrest that reduces the influence of the AC process on human brain SPECT. Methods: To validate the performance of a headrest made of extruded polystyrene (XPS), 10 healthy controls and 43 patients with cerebrovascular disease underwent 99mTc-ethyl cysteinate dimer SPECT using a carbon headrest and an XPS headrest. We evaluated the anterior-to-posterior and middle-to-posterior ratio of the brain regions in filtered backprojection (FBP) Chang AC, ordered-subset expectation maximization (OSEM) Chang AC, and OSEM CT-based AC. Results: The anterior-to-posterior ratio was significantly higher with the carbon headrest than with the XPS headrest in FBP Chang AC and OSEM Chang AC (P < 0.001). There was no significant difference between the materials in OSEM CT-based AC. The middle-to-posterior ratio did not differ to a statistically significant extent in any correction process. Conclusion: Acquisition of brain SPECT images with an XPS headrest and processing by the FBP or OSEM Chang AC method enables the influence of the headrest to be reduced, especially in anterior and posterior brain regions.

Syntactic Impairment Associated with Hypoperfusion in the Left Middle and Inferior Frontal Gyri after Right Cerebellar Hemorrhage.

Cerebellar injuries can cause syntax impairments. Cortical dysfunction due to cerebello-cerebral diaschisis is assumed to play a role in this phenomenon. Functional magnetic resonance imaging studies have repeatedly shown the activation of Broca's area in response to syntactic tasks. However, there have been no reports of selective syntax impairment and hypoperfusion restricted to this area after cerebellar injury. We herein report a patient with right cerebellar hemorrhage that led to marked syntax impairment along with severe hypoperfusion confined to the Brodmann area (BA) 45 (anterior part of Broca's area) and BA46.

Dopamine Transporter Imaging for Frontotemporal Lobar Degeneration With Motor Neuron Disease.

Introduction: Frontotemporal lobar degeneration (FTLD) is a clinical syndrome with pathological heterogeneity, including Pick's disease and trans-activating response region (TAR) DNA-binding protein with a molecular mass of 43 kDa (TDP-43) proteinopathy (FTLD-TDP). A previous study reported abnormal findings on dopamine transporter (DAT) imaging in 30% of patients with frontotemporal dementia (FTD) in FTLD. However, the previous study did not consider the pathological heterogeneity of FTD regarding the pathomechanism leading to abnormal DAT findings. Recently, abnormal DAT findings were reported in two patients with FTLD with motor neuron disease (MND), of which FTLD-TDP type B was the most common pathological presentation. This study investigated the DAT findings of patients with a final diagnosis of FTLD-MND to determine the frequency of occurrence of DAT abnormalities in FTLD-MND. Methods: Twenty patients with FTLD who underwent DAT single photon emission computed tomography (DAT-SPECT) were screened, and six patients with a final diagnosis of FTLD-MND were ultimately included. The patients' DAT-SPECT findings were analyzed visually and quantitatively. Neuronal loss and astrogliosis in brain regions (substantia nigra, caudate, and putamen) that could possibly affect DAT findings were evaluated in the three pathologically confirmed cases. Result: All six patients with FTLD-MND showed abnormal visual DAT-SPECT findings. In addition, in a quantitative assessment, the specific binding ratio in the striatum calculated by the Southampton method was below the lower limit of the 95% prediction interval of the healthy controls by age in all the present cases. Interestingly, three of the six patients showed abnormal findings on DAT-SPECT more than half a year before the onset of MND. Neuronal loss and astrogliosis in brain regions that may affect DAT findings were observed in three pathologically confirmed cases. Conclusion: Dopamine transporter single photon emission computed tomography revealed abnormal findings in patients with FTLD-MND, which may manifest even before the onset of MND symptoms. We believe that the possibility of future development of MND should be considered if DAT-SPECT shows abnormal findings in FTLD.

Comparing Medial Temporal Atrophy Between Early-Onset Semantic Dementia and Early-Onset Alzheimer's Disease Using Voxel-Based Morphometry: A Multicenter MRI Study.

BACKGROUND: Early-onset Semantic dementia (EOSD) and early-onset Alzheimer's disease (EOAD) are often difficult to clinically differentiate in the early stages of the diseases because of the overlaps of clinical symptoms such as language symptoms. We compared the degree of atrophy in medial temporal structures between the two types of dementia using the voxel-based specific regional analysis system for Alzheimer's disease (VSRAD). METHODS: The participants included 29 (age: 61.7±4.5 years) and 39 (age: 60.2±4.9 years) patients with EOSD and EOAD, respectively. The degree of atrophy in medial temporal structures was quantified using the VSRAD for magnetic resonance imaging data. Receiver operating characteristic (ROC) analysis was performed to distinguish patients with EOSD and EOAD using the mean Z score (Z-score) in bilateral medial temporal structures and the absolute value (laterality score) of the laterality of Z-score (| right-left |) for indicating the degree of asymmetrical atrophy in medial temporal structures. RESULTS: The EOSD group had significantly higher Z and laterality scores than the EOAD group (Zscores: mean ± standard deviation: 3.74±1.05 vs. 1.56±0.81, respectively; P<0.001; laterality score: mean ± standard deviation: 2.35±1.23 vs. 0.68±0.51, respectively; P<0.001). In ROC analysis, the sensitivity and specificity to differentiate EOSD from EOAD by a Z-score of 2.29 were 97% and 85%, respectively and by the laterality score of 1.05 were 93% and 85%, respectively. CONCLUSION: EOSD leads to more severe and asymmetrical atrophy in medial temporal structures than EOAD. The VSRAD may be useful to distinguish between these dementias that have several clinically similar symptoms.

Influence of a Headrest on Reconstruction and Attenuation Correction of Human Brain SPECT Images.

Previous reports suggest that a headrest significantly influences anterior and posterior cerebral blood flow. The present study aimed to clarify the influence of a headrest on reconstruction and attenuation correction (AC) of brain SPECT images. Methods: We evaluated the influence on cerebral blood flow in the anterior region (brain segments A + B), middle region (segments D + F), and posterior region (segment G) of the brain using filtered backprojection-AC based on the method of Chang (FBP-ChangAC), ordered-subset expectation maximization-ChangAC (OSEM-ChangAC), OSEM CT-based AC (OSEM-CTAC), and OSEM with no attenuation correction (OSEM-NoAC) with and without a headrest. The subjects were 17 healthy volunteers who underwent 99mTc-ECD SPECT. We compared the A + B/G and the D + F/G ratios of 99mTc-ECD SPECT images in each group. Results: For FBP-ChangAC, OSEM-ChangAC, and OSEM-NoAC, there were significant differences in A + B/G ratio between images obtained with a headrest and those obtained without. On the other hand, for OSEM-CTAC, there were no significant differences in A + B/G ratio regardless of whether a headrest was used. For FBP-ChangAC and OSEM-NoAC, there were significant differences in D + F/G ratio between images with a headrest and those without. For OSEM-CTAC and OSEM-ChangAC, there were no significant differences in D + F/G ratio regardless of whether a headrest was used. Conclusion: The influence of a headrest on image reconstruction and AC should be considered if FBP-ChangAC, OSEM-ChangAC, or OSEM-NoAC is used but not if OSEM-CTAC is used.

Comparison of Alzheimer's disease patients and healthy controls in the easy Z-score imaging system with differential image reconstruction methods using SPECT/CT: verification using normal database of our institution.

OBJECTIVE: The easy Z-score imaging system (eZIS) analysis is used for the diagnosis of dementia by cerebral blood flow on single photon emission computed tomography (SPECT). Differences in the acquisition and reconstruction conditions in SPECT may affect the eZIS analysis results. The present study aimed to construct our institutional normal database (NDB) and Alzheimer's disease (AD)-specific volumes of interest (VOIs) in eZIS analysis, and to compare the differential diagnostic ability between healthy controls (HC) and patients with AD in the image reconstruction filtered back projection (FBP) and ordered subset expectation maximization (OSEM) methods. METHODS: An NDB was constructed at our institution from 30 healthy individual using the FBP and OSEM reconstruction methods. We divided 51 HC and 51 AD patients into two groups, one for AD disease-specific VOI construction (HC, AD) and the other for NDB verification (HC, AD); image reconstruction was performed using FBP and OSEM. The areas of reduced blood flow in AD patients were compared with those of HC using the two types of image reconstruction methods. We used AD disease-specific VOI and NDB from each reconstruction method in eZIS analysis and compared the differential diagnostic ability for HC and AD with the different reconstruction methods. RESULTS: Comparing the areas of reduced blood flow in AD patients using the different image reconstruction methods, OSEM showed decreased blood flow in the medial region of the temporal lobes compared to FBP. Comparing the differential diagnostic ability for HC and AD using eZIS, the Severity, Extent, and Ratio showed higher values in the analysis performed using OSEM image reconstruction compared to FBP. CONCLUSION: With the 99mTc-ECD SPECT, the eZIS analysis equipped with our institutional AD-specific VOI and NDB using OSEM image reconstruction could distinguish HC from AD better than eZIS analysis using FBP image reconstruction. This study is registered in UMIN Clinical Trials Registry (UMIN-CTR) as UMIN study ID: UMIN000042362.

Controlled delivery of bFGF to recipient bed enhances the vascularization and viability of an ischemic skin flap.

Therapeutic angiogenesis is a promising approach to treat ischemic skin flaps. We delivered basic fibroblast growth factor (bFGF) to the recipient bed of a rat dorsal skin flap by a drug delivery system with acidic gelatin hydrogel microspheres (AGHMs), and assessed augmentation of neovascularization and flap viability. An axial skin flap was elevated on the back of male Sprague-Dawley rats, and bFGF solution or bFGF-impregnated AGHMs were injected into the recipient bed. The dose of bFGF in the bFGF solution was set to 15 (Sol-15 group), 50 (Sol-50 group), or 150 mug (Sol-150 group). Correspondingly, 2 mg AGHMs were impregnated with 15 (AGHM-15 group), 50 (AGHM-50 group), or 150 mug (AGHM-150 group) bFGF. Other groups of animals received phosphate-buffered saline (Sol-Cont group) or phosphate-buffered saline-impregnated AGHMs (AGHM-Cont group) as controls. Seven days later, analyses of the area of necrosis, microangiographic findings, and histological findings in the flap were carried out. The area of necrosis in the AGHM-150 group was significantly smaller than that in the other groups. Microangiographic and histological analyses showed that neovascularization of the ischemic skin flap significantly increased in the AGHM-150 group as compared with the Sol-150 group and the AGHM-Cont group. These findings suggest that continuous delivery of bFGF to the recipient bed by bFGF-impregnated AGHMs enhances the viability of an ischemic skin flap.