high density contrast agent

low density contrast agent

direct

indirect

Fast imaging speed, high detection efficiency, low radiation dose

ChestDR

Abdominal DR

BoneDR

breast cancer screening

Guided needle biopsy of breast cancer lesions

Diagnosis and treatment of vascular diseases

Treatment of neoplastic diseases

Heart disease treatment

Grayscale represents the density of tissues and lesions and reflects the X-ray absorption coefficient

Lung tissue containing gas absorbs less X-rays and appears as a dark shadow on CT, that is, low density.

Soft tissues such as muscles absorb moderate doses, gray shadows

Bone tissue absorbs a lot of X-rays, causing white shadows

Water is 1 ct: 0HU

Cortex 2 ct: 1000HU

Air 0 ct:-1000HU

Window level

window width

partial volume effect

Spinal cord inferior to MRI

Small lesions in the gastrointestinal mucosa are inferior to X-ray gastrointestinal tract imaging

Difficulty distinguishing between tumors and non-tumors

Difficult to distinguish between benign and malignant

Difficult to determine tumor pathological type

Short T1 shows high signal

Long T1 shows low signal

Long T2 shows high signal

Short T2 shows low signal

Commonly used contrast agents are paramagnetic chelates containing gadolinium (ga) Gd.

Shorten the T1 value, increase the signal intensity of the lesion on the T1WI image, and improve the contrast.

motion artifacts

Magnetic field unevenness artifact

Magnetic susceptibility artifact

respiratory system

Small lesions of gastrointestinal mucosa

nephrogenic systemic fibrosis

Gadolinium deposition in the brain

Forever forehead seam

grown ups

Child

MRI abdominal aorta pulsatility artifact in the lateral segment of the left lobe of the liver - round-like abnormal signal shadow

Comprehensive, orderly and systematic observation

When reading a chest X-ray: observe the chest wall, lungs, hilus, mediastinum, heart, and great blood vessels in sequence from outside to inside.

Observe the lungs: from the lung apex to the lung base, from the lung hilum to the lung periphery

Combined with examination purpose and clinical requirements

different imaging techniques

different time

Symmetrical parts of the same image

Origin of lesion

Lesion type

Lesion aggressiveness

Lesion growth characteristics

Lesion histological type

Helps in qualitative diagnosis

For disease diagnosis

Often due to the lack of specificity of abnormal lesions, the same abnormal manifestations appear in different diseases.

The same disease may have different abnormal manifestations due to different stages of development or different types.

Unable to detect lesions

Improper timing of inspection

Unable to make qualitative diagnosis

positive diagnosis

negative diagnosis

Possible diagnosis