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Dept. of Radiology
Tongji Hospital, Huazhong University
of Science & Technology,
Wuhan, CHINA
Liang Wang, MD, PhD
Professor, attending radiologist
Justification of the use of CT for
individual health assessment of
asymptomatic people: the Chinese
experience
Knowing asymptomatic is important:
a condition that it fails to show noticeable
symptoms
may develop symptoms later and require watch
and wait or early treatment, e.g. cancer
may resolve itself or become benign
Be alert to possible problems
unknowingly spread the infection to others
Precautionary steps must be taken
Background
Excerpt from Wikipedia
Certain CT procedures for IHA of asymptomatic
people are justified in certain circumstances in
some countries
The proportion of CT exams as source of radiation
is increasing
Technologic advance is profoundly changing our
understanding of the use of CT for IHA of
asymptomatic people
Background
Objectives
to summarize and analyze the utilization of CT for
IHA of asymptomatic people in China
Keypoints:
Feasibility and necessity of CT for IHA of asymptomatic
people in China
Rational use of CT for IHA of asymptomatic people in
China
Current application status of CT for IHA of asymptomatic
people in China
Chinese data:
Usage of CT has increased dramatically over the
last two decades in Chinese hospitals
More than10,000 CT scanners in Chinese
hospitals
Rural community hospitals may have one or more
CT scanners
CT scanners per million Chinese population is 8.6
1.Feasibility and necessity of CT for IHA of
asymptomatic people in China
State-of-the-art imaging modalities in one Top
10 Hospital in China
Tongji University Hospital
Chinese data:
a hospital’s medical statistics
2010:
Out-patients: 2.90 million
In-patients: 86,000
Operations: 42, 000
Certain CT procedures for IHA of asymptomatic
people are justified inChina
The price of a CT exam is cheap in China, e.g.15-
32 € per plain CT head exam
Among medical diagnostic modalities, CT
contributes the most man-made radiation in China
Technology advances are profoundly reducing CT
dose, e.g. coronary CT angiography
Feasibility and necessity of CT for IHA of
asymptomatic people in China
Chest :Coronary CT angiography (CTA)
Patients with myocardial infarction or sudden
cardiac death may be asymptomatic in China
CTA is used as an IHA tool for detecting
coronary artery disease of asymptomatic people
in China, e.g. low dose CTA was used to
evaluate coronary stenosis, and characteristics
of a plaque, especially vulnerable plaque, in
asymptomatic people
2.Rational use of CT for IHA of
asymptomatic people in China
Chest : Coronal CTA
Li, et al published a CTA IHA study in 584
asymptomatic people to assess the prevalence
of noncalcified coronary plaques
38.4% had non-calcified plaques
Conclusions: Hypercholesterolemia and diabetes
mellitus are high risk factors for the prevalence of
noncalcified plaques for asymptomatic people
Rational use of CT for IHA of
asymptomatic people in China
Academic Radiology, Vol 19, No 5, May
2012
Chest : Coronal CTA
Li, et al published a CTA IHA study in 584
asymptomatic people to assess the prevalence
of noncalcified coronary plaques
38.4% had non-calcified plaques
Conclusions: Hypercholesterolemia and diabetes
mellitus are high risk factors for the prevalence of
noncalcified plaques for asymptomatic people
Rational use of CT for IHA of
asymptomatic people in China
Academic Radiology, Vol 19, No 5, May
2012
Chest: Coronal CTA
Dual source CT (DSCT) with adaptive sequence is
currently considered to be the most effective tool to
reduce radiation dose of CTA in China
Xu, et al, published a DSCT IHA study to evaluate
coronary artery stenosis in early diabetes or
prediabetes asymptomatic myocardial ischemia.
Diabetes Care 2013;36(6):1687-94
Rational use of CT for IHA of
asymptomatic people in China
Chest: Coronal CTA
Lv, et al. demonstrated volume CT dose index
(CTDIvol) produced by prospective ECG gating CTA
was about a quarter of the value with retrospective
ECG gating CTA in their study
Rational use of CT for IHA of
asymptomatic people in China
Indications for Coronal CTA as an IHA tool for
asymptomatic people in China
Rational use of CT for IHA of
asymptomatic people in China
men
elderly over the age of 40
family history of premature
coronary heart disease,
smoking (current smoking
> 10 cigarettes / day)
high blood pressure
high cholesterol
severe obesity
(overweight> 30%)
history of cerebral
vascular or peripheral
vascular occlusion
Chest :lung
Most IHAs focus on the detection of early-stage
lung cancer and lung damage of asymptomatic
smokes with CT in China
Rational use of CT for IHA of
asymptomatic people in China
Chest :lung
Wang, et al.published a low dose CT IHA study in the
population > 40 years old.In 500 cases, there were 6
cases of lung cancer
tube voltage 120-140kV
tube current 10-30mA for 50 kg body weight, 20-30mA for
60 kg body weight, 30mA for > 80 kg body weight
image quality could meet diagnostic requirements,
radiation dose has decreased by 75-90%
Rational use of CT for IHA of
asymptomatic people in China
Chest :lung
Li, et al. published an IHA study of low-dose lung
HRCT (tube voltage 120kV, tube current 40 mAs)
to investigate the lung damage of asymptomatic
smokers and non-smokers
found that the incidence of lung emphysema, air
trapping and pulmonary parenchyma
micronodule were significantly increased in
smokers than non-smokers
Rational use of CT for IHA of
asymptomatic people in China
Chinese guidelines on lung cancer IHA with low
dose CT
Age of 40 years or above
high-risk groups:
smokers and passive smokers,
family history of cancer
occupational dust or radiation exposure history
regular contact with cooking oil fumes (COF)
Rational use of CT for IHA of
asymptomatic people in China
Head
Head CT is used as an IHA tool for
detecting intracranial lesions, skull
lesions and other head diseases of
asymptomatic people in China
Rational use of CT for IHA of
asymptomatic people in China
Head
Wang, et al published a head CT IHA study of 21,358
asymptomatic people
demonstrated asymptomatic cerebral infarction (ACI)
prevalence was 3.84%, followed by sinusitis,
encephalomalacia, intracranial tumors and skull bone
tumors
ACI is low before the age of 40
ACI rise after the age of 40 years old
Rational use of CT for IHA of
asymptomatic people in China
Head
Ding, et al, published a head study with low dose
CTA (tube voltage 80kV, tube current 150 mAs) to
investigate intracranial aneurysms (ICA)
Effective radiation dose was reduced by 69.73%
no significant differences in sensitivity, specificity and
accuracy for the detection of ICAs
Rational use of CT for IHA of asymptomatic
people in China
Indications for low-dose head CT as a IHA tool
for asymptomatic people in China
Rational use of CT for IHA of
asymptomatic people in China
40-49 years old with
high blood pressure
Diabetes
Smoking
Alcoholism
family history of stroke and
intracranial arterial
stenosis
over 50 years old
routine annual low-dose
CT IHA for head
diseases
less than 40 years old
not recommended for
routine CT to avoid
ionizing radiation
Head: Nasopharynx
Globally, 80% of patients with nasopharyngeal
carcinoma (NPC) are in China
Early NPCs are mostly asymptomatic but can
be detected by IHA with CT
Rational use of CT for IHA of
asymptomatic people in China
Head: Nasopharynx
Chen, et al, published a study with low dose
skull base CT ( a decrease in tube current
from 200 mAs to 70 mAs)
ocular radiation was reduced (from
145.38mGy to 50.34 mGy)
image quality is not significantly sacrificed
Rational use of CT for IHA of
asymptomatic people in China
Indications for low-dose CT as a NPC IHA tool
for asymptomatic people in China
Rational use of CT for IHA of
asymptomatic people in China
Liver in the southern provinces of China
Aged 30 to 59 years
Family history of NPC
regular contact with cooking oil fumes (COF),
carcinogenic chemicals
Tobacco and alcohol use
Abdomen and pelvis
Early neoplasms of abdomen and pelvic, such as
HCCs, are mostly asymptomatic but can be
detected by IHA with CT
High tube current is usually used in routine
abdominal and pelvic CT to obtain high image
quality, which leads to a high radiation dose to the
patient
Simply reducing tube current leads to an increase in
image noise
Rational use of CT for IHA of asymptomatic
people in China
Abdomen and pelvis:liver
Xu, et al, used iDOSE enhanced CT iterative
reconstruction technique to obtain high-quality
images at lower dose levels
effective dose (ED) was reduced by 49.71%
Rational use of CT for IHA of asymptomatic
people in China
Indications for low-dose liver CT as an IHA
tool for asymptomatic people in China
HCC Risk Factors & High Risk Populations
Rational use of CT for IHA of
asymptomatic people in China
Hepatitis B
Infection
Hepatitis C
Infection
Alcohol
Aflatoxin B1
Drugs, medications, chemicals,
such as vinyl chloride
Hemochromatosis
Cirrhosis
Abdomen and pelvis:Pancrease
Hu, et al, published a pancrease study with
low dose GE lightspeed VCT (abdominal
circumference/current: < 90cm/60-80mA; 90-
110cm/70-90mA; 110cm/90-100mA)
to obtain high-quality imaging at lower
radiation dose
Rational use of CT for IHA of
asymptomatic people in China
Abdomen and pelvis:kidney
Mu, et al, published a RCC IHA with CT (tube
voltage 120kV, tube current 100 mAs)
obtained satisfactory perfusion images
effective radiation dose was 8.95mSv
Rational use of CT for IHA of
asymptomatic people in China
Indications for low-dose kidney CT as an IHA
tool for asymptomatic people in China
RCC Risk Factors & High Risk Populations
Rational use of CT for IHA of
asymptomatic people in China
Over 40 years old
Smoking
Obesity
At other professional such
as oil, leather, asbestos,
other industries
Family history of RCC
Abdomen and pelvis:kidney
Zhu, et al, published a urinary calculi study
with low dose CT (tube voltage 120kV, tube
current 50 mAs)
obtained high quality images to detect urinary
stone
Rational use of CT for IHA of
asymptomatic people in China
Abdomen and pelvis:Bladder
Chen, et al, published a study with low dose
bladder CT (tube voltage 120kV, tube current
40 mAs) after inflating bladder
obtained satisfactory images to detect urinary
lesions
Rational use of CT for IHA of
asymptomatic people in China
Indications for low-dose CT as bladder cancer
IHA tool for asymptomatic people in China
Bladder Cancer Risk Factors & High Risk
Populations:
Rational use of CT for IHA of
asymptomatic people in China
family history of bladder cancer
smokers
contact with carcinogenic chemicals
Abdomen and pelvis:Colorectum
Chen, et al, published a colorectal cancer
IHA study with low dose CT (tube current 50
mAs) after inflating colorectum
obtained satisfactory images
sensitivity, specificity, and accuracy were
96.5%, 62.5%, 89.2%, respectively
Rational use of CT for IHA of
asymptomatic people in China
Indications for low-dose CT as a colorectal
cancer IHA for asymptomatic people in China
Rational use of CT for IHA of
asymptomatic people in China
positive
immunoassay fecal
occult blood test
first-degree relatives
with colorectal
cancer
history of cancer
history of intestinal
polyps
have both or more of the following:
chronic diarrhea
chronic constipation
bloody stool
mucus containing stool
psychiatric injury
history of chronic appendicitis
Bone
Feng, et al, published a lumbar disc
herniation (LDH)IHA with CT in
asymptomatic air force fighter jet pilots
LDH accounted for 27%
Rational use of CT for IHA of
asymptomatic people in China
Bone
Zheng, et al, used iterative reconstruction
technique in 256-slice lumbar spine CT to
obtain high-quality imaging at lower radiation
dose
Rational use of CT for IHA of
asymptomatic people in China
3.Current application status of CT for IHA
of asymptomatic people in China
Certain CT procedures for IHA of asymptomatic
people are justified inChina
CT for IHA of asymptomatic people is being
performed in China
CT examinations for IHA of asymptomatic people
mainly reimbursed by employers in China
Multidisciplinary research efforts is profoundly
changing our understanding of the use of CT for IHA
of asymptomatic people in China