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Lacrymal (Tear Duct) Study or

Dacroscintigraphy Study

Procedure:

  • You have been referred for a Tear Duct study in which imaging is done of your eyes.

  • A tear duct study is very sensitive in showing blockages within the nasolachrymal system. It also is very useful in determining the location of this blockage within this system.

  • The test involves placing a drop of “tracer” into each eye.

  • The tracer we use is called 99mTc-Pertechnetate (99m-Technetium Pertechnetate).

  • There are rarely any side effects with this tracer.

  • Initial images are done of your face whilst sitting infront of a Gamma Camera (1). This takes 25 minutes.

  • At the end of this 25 minutes, you are allowed to dab any tears that may have been produced.

  • We then take some Delayed images but for only 5 minutes.

  • Often, we require imaging your nasolachrymal system in 3D 'after' the Delayed images. This is called SPECT/CT (2) imaging.

  • With SPECT/CT imaging, the same Gamma Camera simply rotates around your head, taking images all the time. This takes 15 minutes.

  • You receive a slight radiation dose by having a Tear Duct study with SPECT/CT ~ up to 0.95 times your yearly background radiation (3).

 

Patient Preparation:

  • If you are pregnant, trying to fall pregnant or breast-feeding, you must inform our staff.

  • All eyewear must be removed prior the test - this includes contact lenses.

  • If you have had prior imaging e.g. PET, Nuclear Scan, CT, MRI, X-Ray, Ultrasound, etc... please bring these with you.

  • Please also bring your referral and any blood results that you may have had done.

  • There is no preparation for a Tear Duct study i.e. eat and drink as normal.

  • If you are on any medications, please take these as normal.

  • Wear comfortable clothing and minimise the amount of metal jewellery you have on (all metal objects will need to be removed prior to imaging).

  • Important Note: You cannot have this test if you have had a PET or Nuclear Scan within 24 hours prior to this test. If you have had Iodine-131 therapy, allow 4-weeks before having this test. Please ring to discuss booking options.​

 

Breast-Feeding Mothers: Once you have been given the tracer, you need to stop breast-feeding for 24-hours. During this time, you need to express and discard your breast milk as often as required. You will need to bottle-feed your child during this period.

 

(1) A Gamma Camera is a device that detects gamma-rays (gamma-rays are very similar to x-rays) and does not emit any radiation.

(2) SPECT/CT imaging (Single Photon Emission Computer Tomography / Computer Tomography). CT does emit radiation

(3) We all receive a yearly background radiation dose ~ 2.4mSv. Tear Duct Study with SPECT/CT ~ 2.3mSv (0.14mSv/eye+2mSv CT) = 0.95 times yearly background dose.

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