Professor Alex Pitman from Lake Imaging , at St John of God Hospital in Ballarat, graced us with his presence in Hamilton last night, and provided us with an engaging and informative outline of PET scanning.
PET stands for Positron Emission Tomography. This mode of whole-body scanning is very useful in cancer medicine, having a role in the diagnosis and staging of a wide ranger of tumours. For our purposes, it is an indispensable part of the management of almost all lung cancer.
How does PET scanning work? Now I am no expert in this field. However…. a PET scan is a nuclear-medicine test. It involves the injection of a ‘tracer’ into the patient. In Australia, this tracer is universally F-18 fluoro deoxy glucose, or FDG. Essentially this is F-18 fluorine attached onto a glucose molecule. FDG tracks around the body in the same way as glucose; ie, it is taken up by organs to be metabolized. Tumours take up lots of glucose, but metabolize it pretty poorly – so FDG tracer hangs around in them. The F-18 fluorine bit of FDG is radioactive, and emits positrons, which collide with and annihilate electrons, releasing photons. After the contrast injection, and a bit of a rest, a patient goes throught the PET scanner. The photons are detected by the PET scanner, allowing mapping of the tumour (and the body in general). A PET scan is combined with a CT scan, which allows better visual localization of the tumour within the body.
When do we use it?
1. PET scanning is used in combination with CT scanning and anatomical biopsy for the evaluation of solitary pulmonary nodules. If a nodule is too difficult to biopsy without considerable risk to the patient, a PET scan is a useful way of ‘ruling in’ a malignant diagnosis. In Australia, if a nodule is ‘hot’ on PET scan then there is over 90% likelihood of it being a cancer. (In other countries, fungal infections and TB in particular also often turn up and are hot on PET scan. I have seen a patient with a fungal infection in Australia also undergo surgery because a lesion was ‘hot’ on PET scan, so we need to be a bit careful).
PET stands for Positron Emission Tomography. This mode of whole-body scanning is very useful in cancer medicine, having a role in the diagnosis and staging of a wide ranger of tumours. For our purposes, it is an indispensable part of the management of almost all lung cancer.
How does PET scanning work? Now I am no expert in this field. However…. a PET scan is a nuclear-medicine test. It involves the injection of a ‘tracer’ into the patient. In Australia, this tracer is universally F-18 fluoro deoxy glucose, or FDG. Essentially this is F-18 fluorine attached onto a glucose molecule. FDG tracks around the body in the same way as glucose; ie, it is taken up by organs to be metabolized. Tumours take up lots of glucose, but metabolize it pretty poorly – so FDG tracer hangs around in them. The F-18 fluorine bit of FDG is radioactive, and emits positrons, which collide with and annihilate electrons, releasing photons. After the contrast injection, and a bit of a rest, a patient goes throught the PET scanner. The photons are detected by the PET scanner, allowing mapping of the tumour (and the body in general). A PET scan is combined with a CT scan, which allows better visual localization of the tumour within the body.
When do we use it?
1. PET scanning is used in combination with CT scanning and anatomical biopsy for the evaluation of solitary pulmonary nodules. If a nodule is too difficult to biopsy without considerable risk to the patient, a PET scan is a useful way of ‘ruling in’ a malignant diagnosis. In Australia, if a nodule is ‘hot’ on PET scan then there is over 90% likelihood of it being a cancer. (In other countries, fungal infections and TB in particular also often turn up and are hot on PET scan. I have seen a patient with a fungal infection in Australia also undergo surgery because a lesion was ‘hot’ on PET scan, so we need to be a bit careful).
http://regionalmedicine.blogspot.com/2010/02/pet-scanning-in-lung-cancer-and-in.html
No comments:
Post a Comment