Self-calibration of C-arm imaging system using interventional instruments during an intracranial biplane angiography.

PURPOSE: To create an accurate 3D reconstruction of the vascular trees, it is necessary to know the exact geometrical parameters of the angiographic imaging system. Many previous studies used vascular structures to estimate the system's exact geometry. However, utilizing interventional devices and their relative features may be less challenging, as they are unique in different views. We present a semi-automatic self-calibration approach considering the markers attached to the interventional instruments to estimate the accurate geometry of a biplane X-ray angiography system for neuroradiologic use. METHODS: A novel approach is proposed to detect and segment the markers using machine learning classification, a combination of support vector machine and boosted tree. Then, these markers are considered as reference points to optimize the acquisition geometry iteratively. RESULTS: The method is evaluated on four clinical datasets and three pairs of phantom angiograms. The mean and standard deviation of backprojection error for the catheter or guidewire before and after self-calibration are [Formula: see text] mm and [Formula: see text] mm, respectively. The mean and standard deviation of the 3D root-mean-square error (RMSE) for some markers in the phantom reduced from [Formula: see text] to [Formula: see text] mm. CONCLUSION: A semi-automatic approach to estimate the accurate geometry of the C-arm system was presented. Results show the reduction in the 2D backprojection error as well as the 3D RMSE after using our proposed self-calibration technique. This approach is essential for 3D reconstruction of the vascular trees or post-processing techniques of angiography systems that rely on accurate geometry parameters.

Multimodal assessment of regional gray matter integrity in early relapsing-remitting multiple sclerosis patients with normal cognition: a voxel-based structural and perfusion approach.

OBJECTIVE: There is increasing evidence that gray matter (GM) impairment is strongly associated with clinical performance decline. We aim to perform a voxelwise analysis between regional GM (rGM) perfusion and structural abnormalities in early relapsing-remitting multiple sclerosis patients with normal cognition (RRMS-IC) and explore clinical correlate of early rGM abnormalities. METHODS AND MATERIALS: We studied 14 early RRMS-IC patients and 14 healthy age- and sex-matched controls. Brain perfusion single photon emission computed tomography (SPECT), structural MRI, and a comprehensive neuropsychological examination were acquired from all participants. Neuropsychological tests include expanded disability status scale, minimal mental status examination, short physical performance battery, Wechsler memory scale, and quick smell test. Voxel-based morphometry was used for analyzing SPECT and T1-MR images to identify rGM hypoperfusion and atrophy, respectively (RRMS-IC vs controls (group analysis), and also, each patient vs controls (individual analysis)) (p < 0.001). Then, anatomical location of impaired regions was acquired by automated anatomical labeling software. RESULTS: There was no significant difference in total GM volume between RRMS-IC and healthy controls, however, rGM atrophy and hypoperfusion were detected. Individual analysis revealed more rGM impairment compared with group analysis. rGM hypoperfusion was more extensive rather than rGM atrophy in RRMS-IC. There was no spatial association between rGM atrophy and rGM hypoperfusion (p > 0.05). rGM abnormalities correlated with several relevant minimal clinical deficits. CONCLUSION: Lack of spatial correlation between rGM atrophy and hypoperfusion might suggest that independent mechanisms might underlie atrophy and hypoperfusion. Perfusion SPECT may provide supplementary information along with MRI. ADVANCES IN KNOWLEDGE: Association between rGM atrophy and rGM hypoperfusion and their clinical significance in early RRMS-IC is not well described yet. Our study showed that there is spatial dissociation between rGM atrophy and rGM hypoperfusion, suggesting that different mechanisms might underlie these pathologies.

Association of regional cerebral perfusion impairment with gait and balance performance in dizzy patients using brain perfusion SPECT: Voxel-based analysis of a pilot sample.

OBJECTIVES: The purpose of this study was to investigate regional cerebral blood flow (rCBF) reduction in patients with dizziness and perfusion-related clinical impairment using brain perfusion single photon emission tomography (SPECT). METHODS: Thirty-four patients with subjective dizziness and 13 age- and sex-matched healthy controls were studied. Dizziness-related impairments were assessed using the Dizziness Handicap Inventory (DHI) and Short Physical Performance Battery (SPPB). Brain perfusion SPECT scan was acquired from all participants. The carotid intima-media thickness (CIMT) was also measured. Brain perfusion data were qualitatively interpreted in all cases. Voxel-wise analysis was also conducted in 11 patients compared to healthy controls. RESULTS: Thirty-four patients (mean age=53.8±13.4 years, m/f: 19/15) and 13 age- and sex-matched controls (mean age=51.5±13.1, m/f: 7/6) were included. The dizziness severity was mild in 58.8% (n=20), moderate in 26.5% (n=9), and severe in 14.7% (n=5). Qualitative interpretation of SPECT images showed normal scans in 4 (11.2%) patients and abnormal scans in 30 (88.2%) patients. Patients with dizziness showed a significantly decreased brain perfusion in the precuneus, cuneus, occipital lobe (superior and inferior parts), frontal lobe (inferior and middle parts), temporal lobe, parietal lobe (inferior and superior parts), cerebellum, insula, and putamen nucleus. Based on both qualitative SPECT interpretation and voxel-wise analysis, perfusion defect had a significant association with the total SPPB score and the scores of two sub-domains (p<0.05), but not with the DHI (p>0.05) score. CONCLUSION: The perfusion- and atherosclerosis-related impairments of gait and balance were largely independent of subjective dizziness and dizziness severity. Moreover, this study provided support for contribution of perfusion impairment to the disturbance of gait and balance in older populations along with other pathologic processes.

Brain perfusion imaging with voxel-based analysis in secondary progressive multiple sclerosis patients with a moderate to severe stage of disease: a boon for the workforce.

BACKGROUND: The present study was carried out to evaluate cerebral perfusion in multiple sclerosis (MS) patients with a moderate to severe stage of disease. Some patients underwent hyperbaric oxygen therapy (HBOT) and brain perfusion between before and after that was compared. METHODS: We retrospectively reviewed 25 secondary progressive (SP)-MS patients from the hospital database. Neurological disability evaluated by Expanded Disability Status Scale Score (EDSS). Brain perfusion was performed by (99 m) Tc-labeled bicisate (ECD) brain SPECT and the data were compared using statistical parametric mapping (SPM). In total, 16 patients underwent HBOT. Before HBOT and at the end of 20 sessions of oxygen treatment, 99mTc-ECD brain perfusion single photon emission computed tomography (SPECT) was performed again then the results were evaluated and compared. Brain perfusion was performed by (99 m) Tc-labeled bicisate (ECD) brain SPECT and the data were compared using statistical parametric mapping (SPM). RESULTS: A total of 25 SP-MS patients, 14 females (56 %) and 11 males (44 %) with a mean age of 38.92 ± 11.28 years included in the study. The mean disease duration was 8.70 ± 5.30 years. Of the 25 patients, 2 (8 %) had a normal SPECT and 23 (92 %) had abnormal brain perfusion SPECT studies. The study showed a significant association between severity of perfusion impairment with disease duration and also with EDSS (P <0.05). There was a significant improvement in pre- and post-treatment perfusion scans (P <0.05), but this did not demonstrate a significant improvement in the clinical subjective and objective evaluation of patients (P >0.05). CONCLUSIONS: This study depicted decreased cerebral perfusion in SP-MS patients with a moderate to severe disability score and its association with clinical parameters. Because of its accessibility, rather low price, practical ease, and being objective quantitative information, brain perfusion SPECT can be complementing to other diagnostic modalities such as MRI and clinical examinations in disease surveillance and monitoring. The literature on this important issue is extremely scarce, and follow up studies are required to assess these preliminary results.

Regional Cerebral Blood-Flow with 99mTc-ECD Brain Perfusion SPECT in Landau-Kleffner Syndrome: Report of Two Cases.

Landau-Kleffner syndrome (LKS) is a rare childhood disorder characterized by acquired aphasia and epilepsy. 99mTc-ECD SPECT imaging was performed in two right-handed children with LKS. A relative decrease in perfusion was found in the left frontal-temporal cortices of both patients as well as in the left and right parietal cortices of one patient with aphasia, without clinical epilepsy. The degree of regional cerebral perfusion impairment did not correlate with the severity of the clinical and EEG abnormalities, but the area of hypoperfusion was compatible with the speech area of the brain. Overall, although asymmetrical temporoparietal perfusion appears as a common finding in LKS, SPECT findings in LKS alone cannot elucidate the pathogenic features of the disorder in the brain. Here, we present two cases of LKS in which we investigated SPECT perfusion scans.