醫用磁振造影讀書會

103年6月9號(星期一)讀書會心得

 Topic I : Aortic regurgitation

1.          The clinical presentation of AR is determined by the acuity of presentation, severity of regurgitation, aortic and left ventricular compliance, and LV end diastolic volume.

2.          AR results from abnormalities of the aortic leaf lets or their supporting structures, aortic root annulus, or both.

3.          It is important to note that chronic AR by itself may lead to progressive aortic root dilatation over time.

4.          Progressive LV dilation and systolic hypertension increase LV wall stress. As this occurs, there is a phase during which LV ejection fraction is still normal, but early myocardial dysfunction develops that is largely masked by increased preload. Peak elastance on the LV pressure volume relationship is decreased at this stage.

5.          Color Doppler echocardiography. Color flow jets are composed of three distinct segments. These are the proximal isovelocity surface area (PISA). Comparison of ratio of the width of the AR jet to the width of the LV outflow tract (LVOT) in the parasternal long axis view is one semiquantatitive measure of AR severity. ( < 25%: mild AR; > 65%: severe AR)

6.          Careful attention to accurate assessment of LV dilatation and systolic function, size of the ascending aorta and aortic root, and etiology of AR, plus accurate quantification of the severity of AR, are imperative to the successful management of patients with this condition.

Question: How the artifact formed in figure 28-20?

 

 Topic II : Atrioventricular, Intraventricular, and  Interventricular Dyssynchrony

1.     Dyssynchrony:  heart failure, LVEF↓ ,conduction delay  
2.     when to conduct the Cardiac resynchronization therapy (CRT)? 
3.     Electrical dyssynchrony  ex. Left bundle branch block (LBBB) or RBBB 
4.     Mechanical dyssynchrony: disruption of myocardial collagen regional wall motion abnormality

            => force of contraction↓,   mitral regurgitation↓,   postsystole contraction

5.       Imaging techniques and identification of dyssynchrony

           - Echocardiography - M mode, strain imaging, TDI

           - MRI - tagged MRI, velocity-encoded MRI


張孟筑 / 2014-06-22

103年5月26號(星期一)讀書會心得

Topic I : Pulmonary and tricuspid disease

1.      Introduction

To the right ventricle, tricuspid valve is inflow valve and pulmonary valve is outflow valve. Tend to be more affected to congenital disease of the heart. TTE (transthoracic echocardiography), TEE (transesophageal echocardiography), 3D echocardiography, MRI.

2.      Normal tricuspid valve anatomy and physiology

Three leaflets (anterior, septal, posterior). Tricuspid valve annulus is slightly apically displaced. (Can help distinguish from mitral valve in many complex congenital diseases where situs is uncertain.) Gerbode defect.

3.      Normal pulmonary valve anatomy and physiology

Pulmonary valve is a semilunar valve and has three cusp.

4.      Imaging of the normal valves

Doppler echocardiography can be used to determine the presence of regurgitation or stenosis. Pulmonic valves are technically difficult to visualize. Mild tricuspid regurgitation (TR) is present in approximately 70% of normal adults. More severe TR may result from leaflet abnormalities or from dilatation of the annulus. Congenital conditions: Ebstein anomaly, rheumatic(風濕性) disease. Tricuspid stenosis (TS) is more prevalent in areas with a high incidence of rheumatic fever. TS is more common in women. Pulmonary regurgitation (PR) is rare. Significant pulmonary stenosis (PS) usually presents in infancy or childhood, given the predominance of congenital PS. Several studies have demonstrated that PS does not progress in 75% of patients with congenital PS. (symptom may resolve by adulthood)

Topic II : Pathophysiology

1.   Tricuspid regurgitation

       -收縮期間血流回流到左心房          -造成左心房及肺動脈壓力上       -導致 right-sided heart failure

       -可分為  (a) primary/intrinsic valve pathology :  Congenital anomalies, less common

                        i. Ebstein’s anomaly:     分級: degree of displacement, TR,    RA dilation and dysfunction

                              ii. connective-tissue disease   (MFS, osteogenesis imperfect.. )

                     (b) secondary of functional : due to RV hypertension, dilation and dysfunction
    2.    Tricuspid stenosis
             -三尖瓣口面積↓             - Pressure: RA-RV > 2mmHg   when exercise,  ↑  
             -RA dilation , jugular venous distension (頸動脈擴張)
   3.   Pulmonic regurgitation
         - Congenital : bicuspid or quadricuspid pulmonary valve
         - 後天因素:

                (a) rTOF : surgical repair       (b) balloon dilation of pulmonary stenosis

                (c) Pulmonary hypertension→  dilation of pulmonary artery & valve annular  →PR

   4.   Diagnostic evaluation

     - evaluation of RV function : wall thickness, shape, ventricular cavity size  and contractile   function
     -Estimation of pulmonic regurgitation severity

         (a) Echo : 有困難  ∵ its anterior position and complex shape

         (b) 3D echo: 看型態

         (c) unclear imaging: 看功能

         (d) MRI: quantify regurgitation volume, RV volume, ejection fraction

              Ps. 若逆流太嚴重或範圍太大,TDI無法看 ∵ brisk and laminar regurgitant flow.

              此時用CMRMPAratio of forward and reversed flow來做follow up

         

 


張孟筑 / 2014-06-02

103年3月24號(星期一)讀書會心得

 時間: 103年3月24日 星期一 18:00-20:00

 地點: 醫環館 R412

 導讀人: 彭旭霞老師

 成員: 王弘軒,吳晨華,周子鈺,陳品蓁,陳毅,張孟筑

 

內容:

I. Quantitative 2D and 3D phase contrast MRI

 reporter : 陳品蓁

Abstract: The limited spatiotemporal resolution and signal-to-noise (SNR) restricts the analysis of 3D PC-MRI CINE. Authors proposed a method that combines B-spline interpolation and Green’s theory to provide optimal quantification of aortic blood flow and vessel wall parameters. Several formula were showed in the article, which gives valuable information for evaluating second hemodynamic parameters. In particular, derivation of computational fluid dynamics (CFD) models with realistic boundary conditions for flow analysis was the important concept overall. For me, it’s necessary to understand as much as possible. Only when realize how data exported after algorithms, the states we made will be reasonable.

Q1: What scale is the difference between the resolution of 2D and 3D PC-MRI CINE?

A1: 2D-CINE-PC has higher spatiotemporal resolution (~1.4x1.4 mm^2, TR= 24.4 ms),

      where 3D-CINE-PC has lower spatiotemporal resolution (~2.8x1.6x3 mm^3, TR= 48.6 ms).

Q2: How to get the flow parameters such as area, flow rate, peak flow?

A2: PC-MRI CINE with velocity encoding data was the fundamental idea for flow analysis. Thus, all second hemodynamic parameters  

       will be calculated from the velocity data set.

 

II. Noninvasive Estimation of PA pressure, Flow, and Resistance With CMR imaging

reporter: 張孟筑

Abstract: 臨床上定義PAH之標準為: mean pulmonary artery pressure>25mm Hg,通常採用right heart catheterization(RHC)侵入式導管的方式來獲得cardiac output (CO), pulmonary capillary wedge pressure(PCWP), 並計算出 pulmonary vascular resistance(PVR)。本篇對69個被懷疑有PAH病狀之病人進行RHCCMR imaging,以期建立利用非侵入式的方法來得到以上參數。其對SSFPfour-chamber short axis進行分析,最後得到:

       -    CMR-predicted mPAP = –4.6 + (interventricular septal angle × 0.23) + (VMI × 16.3) 

       -    CMR-derived PCWP = 6.43 + LA volume index × 0.22

 

利用RHCMRI兩方式得到之結果的R square =0.75。希望未來能利用以上放式對rTOF患者進行肺動脈壓力之評估

 

Q&A:

Q1: interventricular septal angle 如何得到?

A2: short axismiddle-slice @early-diastole時,取 insertion point兩點與mid-point of septum得到角alpha

      而insertion point兩點與mid-point of LV free wall得到角betaSeptal angle ratio=alpha/beta

 

Q2 : 承上,為何要於early-diastole選擇那兩個角度?

A2 : 經比較整個cardiac cycle後,發現於early-diastole時,septum有最大  的位移,且normal controlpatients有最大之差

       異,因此選擇此時 間點。


張孟筑 / 2014-04-21
103年6月9號(星期一)讀書會心得 2014-06-22 103年5月26號(星期一)讀書會心得 2014-06-02 103年3月24號(星期一)讀書會心得 2014-04-21


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