HRCT is a great diagnostic tool in the modern era of technology, through this blog we will discuss the uses, procedures and possible risks of HRCT scan.
High-resolution computed tomography is known as HRCT, it is also called HRCT chest or HRCT of lungs. This diagnostic imaging technique forms thin-slice chest images that are obtained and processed in a high-frequency reconstruction algorithm. The HRCT scan images are used to diagnose various diseases occuring in the chest region such as cystic lung disease. HRCT scan uses x-rays to produce scan images. These x-rays are emitted out of the scanner source on your chest. The x rays hit your body and are reflected on the collecting plate. The signals are then sent to the computer for further evaluation and processing. The computer i turn stores the information and displays it.
Why is HRCT Done?
HRCT scan is considered as the choice of diagnostic tool to check and evaluate various lung abnormalities with unexplained chest symptoms. Some are mentioned below-
- Emphysema
- Bronchiolitis obliterans which may be a sign of graft rejection
- Non specific interstitial pneumonitis
- Desquamative interstitial pneumonitis
- To help plan biopsy procedures
- Lymphangitis carcinomatosa
- Lymphangioleiomyomatosis
- Sarcoidosis
- To check lung complications due to long term drug and immunosuppressive treatment
- To diagnose COVID-19
- Lymphatic spread of carcinoma
- Coal worker’s pneumoconiosis
- Lymphoid interstitial pneumonitis
- Tuberculosis
- Bronchopneumonia
- Endobronchial spread of tumour
- Hematogenous metastasis and diffuse sarcoidosis.
What to Prepare Before HRCT Scan?
- HRCT scan is typically a non invasive and pain-free diagnostic test.
- The HRCT scan does not use any contrast media for the test conduction.
- You can continue eating and drinking as usual, in certain cases it is recommended not to eat which is usually guided by your healthcare provider.
- You are asked to change your clothes to hospital gown for the scanning.
- You should bring doctors prescription along
- You are not allowed to wear any jewellery during the procedure, it's better to leave them at home.
- If you have had a scan for the same area, you should bring them along.
What Happens During the HRCT Scan Procedure?
- You will be asked to lie on a scan table
- The scan table slides into the donut shaped scanner
- The scanner operates while producing loud thumping and clicking sounds.
- You are given headphones or earplugs for noise cancellation, you can always request your investigator to play songs.
- Once the scan is done the scanning table slides out of the scanner.
- The scan procedure usually takes about half hour depending on preparation
- If you feel any king of discomfort during the scan, there is intercom facility through which you can talk to your technologist.
How Do You Feel During the HRCT Scan?
- The HRCT test is specifically a painless and non-invasive procedure. You usually don't feel anything during the test
- The HRCT scan machine produces loud thumping and banging noises while scanning, which might feel uncomfortable. Although you can ask for earplugs or headphones and request your technologist to play a music of your choice or a white nose for noise cancellation
- The scan table is hard which might be uncomfortable to some people. However if you feel very uncomfortable, you can ask for a pillow and bedsheet.
What Happens After the HRCT Scan?
- You can continue your chores as usual unless otherwise instructed
- Your scan reports are generated and made available to you within 1 2 days after the scan.
- You can drink and eat as normal
What Are the Risks Associated to HRCT Scan?
- For any radiation based scan to be done, the technologists are taught to follow the “ALARA” principle (i.e. as low as reasonably possible) which ensures keeping the safety of the workplace and you in terms of radiation exposure.
- The radiations used are kept under safety limits.
- The radiation can cause potential DNA damage. This DNA damage can cause cancer by initiating carcinogenic growth of cells.
- The risk of developing cancer from one scan is significantly low, although the cumulative effect of multiple scans has led to adverse effects in the long term.
- If you are pregnant, you should avoid getting the scan. The foetus is more susceptible to radiation, which can cause developmental disorders and thereby hampering the quality of life later.
- For children the radiation exposure should be avoided as children are more susceptible to radiation.
Conclusion
HRCT scan is an advanced diagnostic tool that can help in diagnosis and evaluation of various health problems. The cost of HRCT scan depends upon various factors like the availability of a HRCT machine in the centre, the location of the diagnostic centre, and others. Diagnosing the condition stands utmost important, and diagnosing a disease early in its course has more value and improved prognosis as well.
Frequently Asked Questions
Can HRCT detect TB?
High resolution computed tomography is considered to be a more sensitive test than other traditional chest x-rays. This test can be used for the diagnosis of any exudative lesion of the chest like pulmonary TB, etc.
What is the cost of HRCT?
The cost for HRCT can vary according to different diagnostic centres, area and its availability. It usually varies between 5000-10000 INR
Is HRCT harmful for humans?
The HRCT scans are usually performed under safety protocols. The dose of radiation that you will be exposed to is too low to cause any potential damage or side effects in one time. Although evidence of developing carcinogenic growth of cells on multiple long term radiation exposure.
What is better CT or HRCT?
The CT scan usually takes pictures and creates 3-5 mm slices while a HRCT scan can make smaller slices i.e. 1mm. The smaller the slices size, the greater the resolution. Therefore the HRCT scans are relatively more accurate and better in resolution than a normal CT scan.
How much time does HRCT scan take?
The HRCT scan in particular takes only upto 10 minutes but the waiting period, the preparation and documentation might constitute a little longer.
How accurate are the HCT scans?
For a HRCT test, negative predictive value (NPV) and positive predictive values (PPV) along with its sensitivity, specificity and diagnostic accuracy are 93.94%, 66.7%, 90.00%, 77.50% and 81.67%. Which renders the HRCT test an effective and precise test.
Does the HRCT use contrast dye?
The intravenous radioactive contrast dye is not used in the HRCT test. The HRCT is used to examine soft tissue i.e. lung. Because the lungs have a very high contrast inherently, the need for additional contrast is eliminated.
Which scan is used for TB detection?
Conventional chest x-rays are the most used diagnostic method for TB. although the other high resolution imaging techniques are also helpful like, PET-CT scan, MRI scan, CT scan, and HRCT scan.
