December 8, 2022

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Lung cancer: It is necessary to do PET-MRI examination except PET-CT?

PET-MRI, which is more “powerful” than PET-CT, is it necessary for lung cancer patients?

Lung cancer: It is necessary to do PET-MRI examination except PET-CT? The names of the two examinations are similar, but PET-MRI examinations may not be well understood by many people.

PET-CT is one of the artifacts of lung cancer examination. The guidelines also recommend PET-CT as one of the examinations for the diagnosis of lung cancer and the observation of imaging staging.

However, a patient friend asked a while ago: Where can I get a PET-MRI examination? Is this examination clearer than PET-CT? Can I diagnose my lung nodules for benign and malignant?

The names of the two examinations are similar, but PET-MRI examinations may not be well understood by many people.

PET-MRI examination is a new technology that combines the molecular imaging function of PET (positron emission computed tomography) with the excellent soft tissue contrast function of MRI (magnetic resonance imaging). Another way of writing is PET-MRI. That is, it combines the above two functions, and these two functions can complement each other.

Therefore, compared with other methods, PET-MRI has high sensitivity and good accuracy, and has the value of early detection and early diagnosis for many diseases (especially tumors and the most common heart and brain diseases).

In many countries, PET is also regarded as the best means of physical examination, and regular PET-MRI examinations can find some early asymptomatic patients.

1. What are the advantages of PET-MRI examination?

The difference between PET-MRI and PET-CT is that MRI and CT, that is, magnetic resonance and CT that we often compare.

First of all, the parameters and high tissue resolution of magnetic resonance imaging are several times higher than that of CT, and the contrast of soft tissue is also higher than that of CT, which means that the picture is clearer; MRI can also provide bleeding, distribution, perfusion, local biochemical, metabolic status, Information such as oxygen consumption provides more supplementary information for PET metabolism imaging.

Therefore, PET-MRI can detect soft tissue lesions more effectively and earlier.

Secondly, MRI can show the heart cavity, myocardium, pericardium and other small structures in the heart without angiography. It can be said that PET-MRI can find out whether there are dangerous tiny lesions in the whole body in one inspection.

Furthermore, MRI has great advantages in tumor diagnosis, cardiovascular disease assessment, and neurological disease diagnosis.

Finally, because magnetic resonance does not have radiation, it is of greater value to patients such as children and adolescents than CT and MRI.

2. What are the shortcomings of PET-MRI examination?

The first thing that discourages many people is the price of PET-MRI. Due to the high price of the equipment, there are currently few medical institutions purchasing the equipment in the country, making this inspection expensive, nearly 20,000, which is one of the reasons why it is niche.

Secondly, PET-MRI has not been widely used, and its diagnosis has not been proved to be correct; besides, PET and MRI systems may affect each other, and further observation and improvement are needed.

Furthermore, if a person has a metal or a pacemaker installed in the body, this test cannot be done.

Finally, the magnetic resonance in the PET-MRI examination is the same as ordinary magnetic resonance, and it is difficult to have a better image of the gastrointestinal tract, lungs and other hollow organs and moving organs.

Therefore, the diagnosis of lung nodules is mainly based on CT!

3. What kind of help can ordinary MRI examinations bring to patients with lung cancer?

Many medical experts have made different recommendations for MRI examination and PET-CT examination:

(1) MRI examination is not recommended for routine diagnosis of lung cancer, but lung cancer patients may need it in the following situations:

Judging the chest wall or mediastinum invasion, showing the relationship between superior lung tumors and brachial plexus nerves and blood vessels, especially suitable for judging brain and vertebral body metastases;

Enhanced brain MRI can be used as a routine examination before lung cancer surgery or initial stage of treatment;

MRI has high sensitivity and specificity for vertebral body and bone metastasis, and can be selected according to clinical needs.

(2) PET-CT examination is one of the best methods for the diagnosis of lung cancer, staging and re-staging, radiotherapy target area delineation, and evaluation of efficacy and prognosis. It is also one of the inspection methods recommended by the guidelines.

However, PET-CT has relatively poor sensitivity to brain and meningeal metastases. If the patient needs to rule out brain metastasis, it is recommended to combine with brain enhancement MRI to improve the diagnosis rate. Of course, chest enhanced CT, abdominal enhanced CT or B-mode ultrasound (including supraclavicular lymph nodes), head enhanced CT or MRI, and whole body bone scan can also be performed according to the specific situation.

4. Summary:

PET-MRI examination has great advantages in tumor diagnosis, cardiovascular disease assessment, and neurological disease diagnosis, but it is not very helpful in the diagnosis of lung nodules in patients with lung cancer, and it is more expensive.

For staged diagnosis of lung cancer patients, PET-CT and brain-enhanced MRI can be performed for those with conditions.

(source:internet, reference only)


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