Wall Shear Stress Associated with Stroke Occurrence and Mechanisms in Middle Cerebral Artery Atherosclerosis / 대한뇌졸중학회지

Background@#and Purpose Various mechanisms are involved in the etiology of stroke caused by atherosclerosis of the middle cerebral artery (MCA). Here, we compared differences in plaque nature and hemodynamic parameters according to stroke mechanism in patients with MCA atherosclerosis. @*Methods@#Consecutive patients with asymptomatic and symptomatic MCA atherosclerosis (≥50% stenosis) were enrolled. MCA plaque characteristics (location and plaque enhancement) and wall shear stress (WSS) were measured using high-resolution vessel wall and four-dimensional flow magnetic resonance imaging, respectively, at five points (initial, upstream, minimal lumen, downstream, and terminal). These parameters were compared between patients with asymptomatic and symptomatic MCA atherosclerosis with infarctions of different mechanisms (artery-to-artery embolism vs. local branch occlusion). @*Results@#In total, 110 patients (46 asymptomatic, 32 artery-to-artery embolisms, and 32 local branch occlusions) were investigated. Plaques were evenly distributed in the MCA of patients with asymptomatic MCA atherosclerosis, more commonly observed in the distal MCA of patients with artery-to-artery embolism, and in the middle MCA of patients with local branch occlusion. Maximum WSS and plaque enhancement were more prominent in the minimum lumen area of patients with asymptomatic MCA atherosclerosis or those with local branch occlusion, and were more prominent in the upstream area in those with artery-to-artery embolism. The elevated variability in the maximum WSS was related to stroke caused by artery-to-artery embolism. @*Conclusion@#Stroke caused by artery-to-artery embolism was related to plaque enhancement and the highest maximum WSS at the upstream point of the plaque, and was associated with elevated variability of maximum WSS.

Effective End-to-End Deep Learning Process in Medical Imaging Using Independent Task Learning:Application for Diagnosis of Maxillary Sinusitis

Purpose@#This study aimed to propose an effective end-to-end process in medical imaging using an independent task learning (ITL) algorithm and to evaluate its performance in maxillary sinusitis applications. @*Materials and Methods@#For the internal dataset, 2122 Waters’ view X-ray images, which included 1376 normal and 746 sinusitis images, were divided into training (n=1824) and test (n=298) datasets. For external validation, 700 images, including 379 normal and 321 sinusitis images, from three different institutions were evaluated. To develop the automatic diagnosis system algorithm, four processing steps were performed: 1) preprocessing for ITL, 2) facial patch detection, 3) maxillary sinusitis detection, and 4) a localization report with the sinusitis detector. @*Results@#The accuracy of facial patch detection, which was the first step in the end-to-end algorithm, was 100%, 100%, 99.5%, and 97.5% for the internal set and external validation sets #1, #2, and #3, respectively. The accuracy and area under the receiver operating characteristic curve (AUC) of maxillary sinusitis detection were 88.93% (0.89), 91.67% (0.90), 90.45% (0.86), and 85.13% (0.85) for the internal set and external validation sets #1, #2, and #3, respectively. The accuracy and AUC of the fully automatic sinusitis diagnosis system, including site localization, were 79.87% (0.80), 84.67% (0.82), 83.92% (0.82), and 73.85% (0.74) for the internal set and external validation sets #1, #2, and #3, respectively. @*Conclusion@#ITL application for maxillary sinusitis showed reasonable performance in internal and external validation tests, compared with applications used in previous studies.

Intractable Headache Related to Intraventricular Glioblastoma: A Case Report and Literature Review

Although various neoplasms may develop in the ventricular system, glioblastomas are rare. An 80-year-old woman visited our hospital with intractable headache related to a right ventricular large mass, which exhibited heterogeneous enhancement involving the body, trigone, and occipital horn of the right lateral ventricle on MRI. The mass was diagnosed as glioblastoma multiforme on surgical pathology. Herein, the authors present a case and review the existing literature with regarding to incidence, pathophysiology, prognostic factors, imaging and pathologic findings of intraventricular glioblastoma multiforme.

Ethnic Differences in Intracranial Artery Tortuosity: A Possible Reason for Different Locations of Cerebral Atherosclerosis / 대한뇌졸중학회지

No abstract available.

Can Treatment of Patent Ductus Arteriosus with Ibuprofen Compared to Supportive Management Affect Regional Brain Volume in Very Low Birth Weight Infants? A Pilot Study

PURPOSE: This study aimed to compare cerebral hemispheric volumes between pharmacologic treatment and supportive management of patent ductus arteriosus (PDA). METHODS: The study was conducted retrospectively. The subjects of period 1 group were very low birth weight infants whose PDA were treated with pharmacologic closure. Period 2 group were treated with supportive management. Regional brain volumes measured using magnetic resonance imaging were compared between the two groups. RESULTS: total of 12 infants were included. Their median gestational age was 27⁺⁶ (range: 24⁺¹–31⁺¹) weeks and birth weight was 1,065 g (range: 690–1,380). Between the two groups, there was no difference in Apgar score, incidence of bronchopulmonary dysplasia, necrotizing enterocolitis, and culture proven sepsis. The regional brain volumes such as gray matter (Period 1 group, 76,833 mm³ [55,759–100,388] vs. Period 2 group, 79,870 mm³ [59,957–113,018], P=0.59), white matter (82,993 mm³ [63,130–121,311] vs. 92,576 mm³ [77,200–104,506], P=0.18), cerebrospinal fluid (17,167 mm³ [9,279–22,760] vs. 14,348 mm³ [7,018–27,604], P=0.94), basal ganglia (2,065 mm³ [1,697–2,482] vs. 2,306 mm³ [2,065–3,009], P=0.18), and cerebellum (18,374 mm³ [14,843–24,657] vs. 18,096 mm³ [16,134–23,627], P=0.94) were not different between the two groups. CONCLUSION: Regional brain volumes were not different between pharmacological and conservative treatment in infants with PDA. Further wellcontrolled studies are required to evaluate the advantages or disadvantages of supportive management without pharmacologic treatment of PDA.

Estimation of T2* Relaxation Times for the Glandular Tissue and Fat of Breast at 3T MRI System

PURPOSE: T2* relaxation time which includes susceptibility information represents unique feature of tissue. The objective of this study was to investigate T2* relaxation times of the normal glandular tissue and fat of breast using a 3T MRI system. MATERIALS AND METHODS: Seven-echo MR Images were acquired from 52 female subjects (age 49 +/- 12 years; range, 25 to 75) using a three-dimensional (3D) gradient-echo sequence. Echo times were between 2.28 ms to 25.72 ms in 3.91 ms steps. Voxel-based T2* relaxation times and R2* relaxation rate maps were calculated by using the linear curve fitting for each subject. The 3D regions-of-interest (ROI) of the normal glandular tissue and fat were drawn on the longest echo-time image to obtain T2* and R2* values. Mean values of those parameters were calculated over all subjects. RESULTS: The 3D ROI sizes were 4818 +/- 4679 voxels and 1455 +/- 785 voxels for the normal glandular tissue and fat, respectively. The mean T2* values were 22.40 +/- 5.61 ms and 36.36 +/- 8.77 ms for normal glandular tissue and fat, respectively. The mean R2* values were 0.0524 +/- 0.0134/ms and 0.0297 +/- 0.0069/ms for the normal glandular tissue and fat, respectively. CONCLUSION: T2* and R2* values were measured from human breast tissues. T2* of the normal glandular tissue was shorter than that of fat. Measurement of T2* relaxation time could be important to understand susceptibility effects in the breast cancer and the normal tissue.

Correlation of the Speed of Enhancement of Hepatic Hemangiomas with Intravoxel Incoherent Motion MR Imaging

PURPOSE: To evaluate the relationship between the speed of enhancement of hepatic hemangiomas on gadolinium-enhanced MRI and ADC values by using various parameters, including the D, f, D* and ADC(fit) on intravoxel incoherent motion (IVIM) MR Imaging. MATERIALS AND METHODS: The institutional review board approved this retrospective study. A total of 47 hepatic hemangiomas from 39 patients were included (20 men and 19 women). The hemangiomas were classified into three types according to the enhancement speed of the hepatic hemangiomas on gadolinium-enhanced dynamic T1-weighted images: rapid (Type A), intermediate (Type B), and slow (Type C) enhancement. The D, f, D* and ADC(fit) values were calculated using IVIM MR imaging. The diffusion/perfusion parameters and ADC values were compared among the three types of hemangiomas. RESULTS: Both the ADC(fit) and D values of type C were significantly lower than those of type A (P = 0.0022, P = 0.0085). However, for the f and D*, there were no significant differences among the three types. On DWI with all b values (50, 200, 500 and 800 sec/mm2), the ADC values of type C were significantly lower than those of the type A (P < 0.012). For b values with 800 sec/mm2, the ADC800 values of the type C hemangiomas were significantly lower than those of type B (P = 0.0021). We found a negative correlation between hepatic hemangioma enhancement type and ADC50 (rho= -0.357, P = 0.014), ADC200 (rho= -0.537, P = 0.0001), ADC500 (rho= -0.614, P = 0.0001), and ADC800(rho= -0.607, P = 0.0001). Therefore, four ADC values of ADC50, ADC200, ADC500, and ADC800 were decreased with decreasing enhancement speed. CONCLUSION: Hepatic hemangiomas had variable ADCs according to the type of enhancement, and the reduced ADCs in slowly enhancing hemangiomas may be related to the reduced pure molecular diffusion (D).

Simulations of Perfusion Signals of Pulsed Arterial Spin Labeling MRI

PURPOSE: A pulsed arterial spin labeling (PASL) signal usually depends on several parameters. The objective of this study was to determine the optimal parameters using simulation for perfusion signals of PASL magnetic resonance imaging (MRI). MATERIALS AND METHODS: Perfusion signals, DeltaM/M(0b), derived from the Bloch equation were evaluated in regard to the four most important parameters in PASL MRI: the tissue-to-blood coefficient (lambda), the longitudinal relaxation time of blood (T(1b)), the arterial transit delay from the application of tag (deltat), and the magnetic field strength (B0). The simulation was conducted with Mathematica software. RESULTS: First, perfusion signals differed depending on the value of lambda in brain tissue. The maximum signal, DeltaM/M(0b) = 0.390, was obtained at an inversion time (TI) = 1.53 sec for gray matter on 3T MRI. Second, perfusion signals were reduced with increasing deltat. The maximum signal, DeltaM/M0b = 0.526, was obtained at TI = 2.1 sec for deltat = 0.5 sec. Finally, perfusion signals increased with increasing B0. The maximum signal, DeltaM = 1.15, was obtained at TI = 1.52 sec for 3T MRI. CONCLUSION: We reported that the optimized TI values were obtained to provide the highest PASL signals. It is very important that optimized TI values be used to obtain high-quality perfusion signals using PASL MRI.