We investigate the potentials and limitations of computational fluid dynamics (CFD) analysis of patient specific models from 3D angiographies. There are many technical problems in acquisition of proper vascular models, in pre-processing for making 2D surface and 3D volume meshes and also in post-processing steps for display the CFD analysis. We hope that our study could serves as a technical reference to validating other tools and CFD results.
Angiography ; Arteries ; Carotid Arteries ; Hemodynamics ; Humans ; Hydrodynamics

PURPOSE: Computational flow dynamic (CFD) study has not been widely applied in intracranial artery stenosis due to requirement of high resolution in identifying the small intracranial artery. We described a process in CFD study applied to symptomatic severe intracranial (M1) stenosis before and after stenting. MATERIALS AND METHODS: Reconstructed 3D angiography in STL format was transferred to Magics (Materialise NV, Leuven, Belgium) for smoothing of vessel surface and trimming of branch vessels and to HyperMesh (Altair Engineering Inc., Auckland, New Zealand) for generating tetra volume mesh from triangular surface-meshed 3D angiogram. Computational analysis of blood flow in the blood vessels was performed using the commercial finite element software ADINA Ver 8.5 (ADINA R & D, Inc., Lebanon, MA). The distribution of wall shear stress (WSS), peak velocity and pressure in a patient was analyzed before and after intracranial stenting. RESULTS: Computer simulation of wall shear stress, flow velocity and wall pressure before and after stenting could be demonstrated three dimensionally by video mode according to flow vs. time dimension. Such flow model was well correlated with angiographic finding related to maximum degree of stenosis. Change of WSS, peak velocity and pressure at the severe stenosis was demonstrated before and after stenting. There was no WSS after stenting in case without residual stenosis. CONCLUSION: Our study revealed that CFD analysis before and after intracranial stenting was feasible despite of limited vessel wall dimension and could reveal change of WSS as well as flow velocity and wall pressure.
Angiography ; Arteries ; Atherosclerosis ; Blood Vessels ; Cerebral Arteries ; Characidae ; Computer Simulation ; Constriction, Pathologic ; Glycosaminoglycans ; Humans ; Lebanon ; Magic ; Stents

PURPOSE: Image-based computational models with fluid-structure interaction (FSI) can be used to perform plaque mechanical analysis in intracranial artery stenosis. We described a process in FSI study applied to symptomatic severe intracranial (M1) stenosis before and after stenting. MATERIALS AND METHODS: Reconstructed 3D angiography in STL format was transferred to Magics for smoothing of vessel surface and trimming of branch vessels and to HyperMesh for generating tetra volume mesh from triangular surface-meshed 3D angiogram. Computational analysis of blood flow in the blood vessels was performed using the commercial finite element software ADINA Ver 8.5. The distribution of wall shear stress (WSS), peak velocity and pressure was analyzed before and after intracranial stenting. RESULTS: The wall shear stress distributions from Computational fluid dynamics (CFD) simulation with rigid wall assumption as well as FSI simulation before and after stenting could be compared. The difference of WSS between rigid wall and compliant wall model both in pre- and post-stent case is only minor except at the stenosis region. These WSS values were greatly reduced after stenting to 15~20 Pa at systole and 3~5 Pa at end-diastole in CFD simulation, which are similar in FSI simulations. CONCLUSION: Our study revealed that FSI simulation before and after intracranial stenting was feasible despite of limited vessel wall dimension and could reveal change of WSS as well as flow velocity and wall pressure.
Angiography ; Arteries ; Atherosclerosis ; Blood Vessels ; Cerebral Arteries ; Characidae ; Constriction, Pathologic ; Glycosaminoglycans ; Hydrodynamics ; Magic ; Stents ; Systole

In this report, we present a case of a patient with Philadelphia chromosome-positive (Ph+) B-cell acute lymphoblastic leukemia after renal transplantation. The patient, a 65-year-old man, had received a kidney transplantation 20 years prior to diagnosis with Ph+ precursor B-cell ALL. Because he was refractory to intensive chemotherapy and had refused to receive additional intensive chemotherapy, he was treated with imatinib and dexamethasone. While this patient experienced a complete hematologic and cytogenetic response, he did not show a complete molecular remission. Eighty days after imatinib combination therapy, the patient relapsed and died from intracerebral hemorrhage.
Aged ; B-Lymphocytes ; Benzamides ; Cerebral Hemorrhage ; Cytogenetics ; Dexamethasone ; Humans ; Kidney Transplantation ; Philadelphia ; Philadelphia Chromosome ; Piperazines ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; Precursor Cells, B-Lymphoid ; Pyrimidines ; Imatinib Mesylate

Background/Aims: We investigated the real-world effectiveness and safety of ustekinumab (UST) as induction treatment for Koreans with Crohn’s disease (CD). Methods: CD patients who started UST were prospectively enrolled from 4 hospitals in Korea. All enrolled patients received intravenous UST infusion at week 0 and subcutaneous UST injection at week 8. Clinical outcomes were assessed using Crohn’s Disease Activity Index (CDAI) scores at weeks 8 and 20 among patients with active disease (CDAI ≥150) at baseline. Clinical remission was defined as a CDAI <150, and clinical response was defined as a reduction in CDAI ≥70 points from baseline. Safety and factors associated with clinical remission at week 20 were also analyzed. Results: Sixty-five patients were enrolled between January 2019 and December 2020. Among 49 patients with active disease at baseline (CDAI ≥150), clinical remission and clinical response at week 8 were achieved in 26 (53.1%) and 30 (61.2%) patients, respectively. At week 20, 27 (55.1%) and 35 (71.4%) patients achieved clinical remission and clinical response, respectively. Twenty-seven patients (41.5%) experienced adverse events, with serious adverse events in 3 patients (4.6%). One patient (1.5%) stopped UST therapy due to poor response. Underweight (body mass index <18.5 kg/m2) (odds ratio [OR], 0.085; 95% confidence interval [CI], 0.014–0.498; P=0.006) and elevated C-reactive protein at baseline (OR, 0.133; 95% CI, 0.022–0.823; P=0.030) were inversely associated with clinical remission at week 20. Conclusions UST was effective and well-tolerated as induction therapy for Korean patients with CD.

The computational fluid dynamics methods for the limited flow rate and the small dimensions of an intracranial artery stenosis may help demonstrate the stroke mechanism in intracranial atherosclerosis. We have modeled the high wall shear stress (WSS) in a severe M1 stenosis. The high WSS in the systolic phase of the cardiac cycle was well-correlated with a thick fibrous cap atheroma with enhancement, as was determined using high-resolution plaque imaging techniques in a severe stenosis of the middle cerebral artery.
Blood Flow Velocity ; *Cerebral Angiography ; Cerebrovascular Circulation ; Computational Biology ; Humans ; Image Interpretation, Computer-Assisted ; Imaging, Three-Dimensional ; Intracranial Arteriosclerosis/*diagnosis ; *Magnetic Resonance Angiography ; Shear Strength ; Software ; Systole

PURPOSE: Computational fluid dynamics (CFD) applications for atherosclerotic carotid stenosis have not been widely used due to limited resolution in the severely stenotic lumen as well as small flow dimension in the stenotic channel. MATERIALS AND METHODS: CT data in DICOM format was transformed into 3 dimensional (3D) CFD model of carotid bifurcation. For computational analysis of blood flow in stenosis, commercial finite element software (ADINA Ver. 8.5) was used. The blood flow was assumed to be laminar, viscous, Newtonian, and incompressible. The distribution of wall shear stress (WSS), peak velocity and pressure across the average systolic and diastolic blood pressures permitted construction of a contour map of the velocity in each cardiac cycle. RESULTS: Computer simulation of WSS, flow velocity and wall pressure could be demonstrated three dimensionally according to flow vs. time dimension. Such flow model was correlated with angiographic finding related to maximum degree of stenosis associated with ulceration. Combination of WSS map and catheter angiogram indicated that the highest WSS corresponded to the most severely stenotic segment at systolic phase, whereas ulceration, which is the weakest point of the plaque, appeared at the downstream side of the carotid bulb stenosis. CONCLUSION: Our preliminary study revealed that 3D CFD analysis in carotid stenosis was feasible from CT angiography source image and could reveal WSS, flow velocity and wall pressure in the severe carotid bulb stenosis with ulceration. Further CFD analysis is warranted to apply such hemodynamic information to the atherosclerotic lesion in the more practical way.
Angiography ; Carotid Arteries ; Carotid Stenosis ; Catheters ; Computer Simulation ; Constriction, Pathologic ; Hemodynamics ; Hydrodynamics ; Ulcer