財團法人新光吳火獅紀念醫院 放射診斷科 Wai-Yip Law

Multidetector CT (MDCT) 在心臟血管方面的運用

coronary artery lumen

Plaques

LV function

LV perfusion

Left posterior aortic sinus

Left main artery (LM) -- 1- 2 cm

Left anterior descending (LAD)

1. Septal branches

2. Diagonal branches

Left circumflex artery (LCx)

1. Marginal branches

Intermedial artery

Left posterior aortic sinus

Left main artery (LM) -- 1- 2 cmcoronary

anatomy

Left circumflex artery (LCx)

1. Marginal branches

Intermedial artery Anterior aortic sinsus

Right coronary artery (RCA)

1. Marginal branches

Left anterior descending (LAD)

1. Septal branches

2. Diagonal branches

coronary anatomy

Right dominant (80%)

Left dominant()

Balanced type

1. Crux

2. Posterior descending artery (PDA)

3. Posterior lateral branch (PL)

coronary anatomy

1

2

3

4 PDA

5

PL

67

89

10

11

12

13 1415

Seg. Vessel

010203040506070809101112131415

RCARCARCAPDALMLADLADLADD1D2CxMoCXMOPL

Ca-X

coronary artery atheroma

MSCT freatures of plaques (Modified AHA calcification)

Modified AHA

Calcified nodules

Fibrocalcified plaque

Fibreous cap atheroma

Thin fibrous cap atheroma

Trombus

DensityMDCT

>150 High High/Low

50-100 intermediate

20-50 low

<20 very low

Pictrure

coronary artery atheroma

Coronary calcification• The need to detect coronary atherosclerosis early in its cours

e has been well recognized by cardiologists for decades.• The presence and amount of coronary artery calcium have b

een suggested as a means to assess patients at risk of adverse coronary events.

• The presence of coronary calcium is always indicative of the presence of coronary atherosclerosis.

• Agatston et al. developed a calcium scoring algorithm that is now widely used in research and clinical practice.

• The calcium score is derived from the product of the area of calcification(mm2) and a factor determined by the maximal X-ray density within this area. (calcification should be at least 1 mm2 and the X-ray density should exceed the threshold of 130HU)

冠狀動脈鈣化評分

冠狀動脈鈣化

右冠狀動脈 左主幹 左迴旋枝 左前降枝 總合

Agatston

Volume (mm³)

Mass (mg)

Area of plaque × weighting factor

= Lesion score

∑ Lesion scores = Vessels score

∑ Vessels scores = Total calcium score (Agatston Score)

” 冠狀動脈鈣化評分” (the Agatston Calcium Score) 之說明

鈣化評分

粥狀硬化斑塊承載量Plaque burden

有意義冠狀血管阻塞的可能性Significant CAD

心血管之風險

CV risk

0 無動脈粥狀硬化斑塊 可能性極低 ( < 5% ) 極低

1-10極輕度的動脈粥狀硬化斑塊 可能性極低 ( < 10% ) 低

11-100輕微的動脈粥狀硬化斑塊

具輕微或極輕度冠狀動脈狹窄的可能性 中等

101-400中等的動脈粥狀硬化斑塊

高度有冠狀動脈狹窄存在的可能性 中高等

＞ 400高量的動脈粥狀硬化斑塊

極有可能有冠狀動脈狹窄的存在 高等

鈣化分數越高心血管疾病發生機率越高

How to use the calcium score?

• CT calcium quantification can be used for the assessment of long-term risk and primary prevention of future adverse coronary events.

• Calcium scoring should not be performed as a ‘stand-alone’ test but should be integrated into risk assessment with well recognized risk factors.

Risk factors: 1, Sex. 2, Age. 3, Family history. 4, Blood lipids. 5, Smoking. 6, Diabetes. 7, Blood pressure. 8, Weight.

冠狀動脈鈣化性別

百分比

年紀<40 40-

4445-49

50-54

55-59

60-64

65-69

70-74

>74

男 25 0 0 0 1 4 13 32 64 166

50 1 1 3 15 48 113 180 310 473

75 3 9 36 103 215 410 566 892 1071

90 14 59 154 332 554 994 1299 1774 1982

n 3504

4238 4940 4825 3472 2288 1209 540 235

女 25 0 0 0 0 0 0 1 3 0

50 0 0 0 0 1 3 24 52 75

75 1 1 2 5 23 57 145 210 241

90 3 4 22 55 121 193 410 631 709

n 641 1024 1634 2184 1835 1334 731 438 174According to Hoff JA et .al JACC 2003;41;1008-12

Intermediate(1)Calcium score < 80 Lower risk(2)Calcium score > 80 Higher risk

Level description Low risk

0-1 risk factor

Intermediate

2 risk factor

High risk

>3 risk factor

Risk of event within 10 yrs

<10% 10-20% >20%

Estimated prevalence adults

35% 40% 25%

Ca. test useful No Yes No

Electrical Activation of the Heart

ECG-Triggering/GatingECG-Triggering/Gating

600 ms600 ms

Absolute Time

400 ms400 ms

Absolute Reverse

60% RR60% RR

% RR Interval

“3D” Image Data

R R R R

DelayR

econ

Rec

on

Rec

on

Rec

on

Continuous

Spiral Scan & Feed

z -

Pos

itio

n

Time

Retrospective ECG Gating

加圖

Challenges in MSCT coronary imaging

• size of coronary arteries are small

• LCA = 4.4 mm

• LAD = 3.6 mm distally = 0.8 mm

• CX = 3.4 mm distally = 1.5 mm

• RCA = 3.0 mm distally = 1.0 mm

• movement of mid RCA up to 45 mm/sec

small vessel

64 dectector array

Flat Panel

16 dectector array

small vessel

4s 16s 64s

Rotation 0.5 0.42/0.37 0.33

Temp resolution 0.25 0.21 0.165

Spatial resolution 1.0 0.75 0.35

Data per rotation 4 16 64

Scan time >40s 20s 14s

Vascular

Enhancement

Rate

4-slice 16-slice 64-slice

120 ml 100 ml 80 ml

3 ml/sec 4 ml/sec 5 ml/sec

Volume

Concentration > 350mg/ml

Antecubital access

Patient SelectionPatient Selection

Small coronary arteries

Fast heart rate >75 bpm

Persistent irregular heart rhythm

Respiratory impairment and related motion artifacts

Diffuse and calcified coronary atherosclerosis

Coronary stents

Metal objects

Renal dysfunction and contrast medium allergy

motion artifacts

60 NTG Diastolic

60-80 Beta-blocker

80 Systolic

β- blocking agent

- Metoprolol (Beloc ®) 100 mg 1h prior to exam. p.o.

- Propranolol(Dociton ®) 80 mg 1h prior to exam. p.o.

- i.v. Metoprolol 5 mg @1mg/min i.v.

check heart rate @ 5 minutes

repeat @ 5 mg (15 mg max.)

NTG

Patient education 1. Breath holding

2. CM burning sensation

64 dectector array : >9 sec (12)

16 dectector array : >15 sec (20)

coronary anomaly

1%

coronary

anomaly

bridge

Absent right coronary

Left Anterior Descending stenosis

coronary artery lumen

Proximal LAD stenosis

coronary artery lumen

CABG

CABG

RL

CABG

(Blooming)

Volume averaging

Contrast material

StentsCalcium

Bean hardening

(Streak artifacts)

stents

Contrast material

Pacemaker wires

Prosthetic valve

Surgical clips

Calcium

Effective energy is shifted to higher value as the X-rays pass through an object

Sternal wires

Resolution

Furture

small vessel(spatial resolution)

motion artifacts(temporal resolution)

Calcium/stent

obstruction estimation

Radiation exposure

Thanks for you attention!