Takayasu Arteritis and PET/CT

Takayasu arteritis is one of the indications that we perform an F18 FDG PET/CT scan on, primarily as a research protocol.  This is one of those research studies that we do not do very frequently but once in awhile they pop up on our list.  

What is interesting about this condition, besides the name, is that this is a rare condition that causes vasculitis in the large vessels, such as the aorta and it's branches.  

The history of Takayasu arteritis is pretty interesting as well.  Originally this vascular disease was reported by Dr. Mikito Takayasu, an ophthalmologist in 1908 at the 12th Annual Meeting of the Japan Opthalmology Society. It basically came about with the appearance of "coronary anastomosis" in the eyegrounds and arteriovenous anastomosis around the papila of a 21 year old woman that Dr. Takayasu was examining.  Further investigation lead others to report "pulselessness" in their patients which is another clinical feature.  The radial, brachial and carotid pulses are absent in these patients as the result of the ischemic cerebrovascular circulation.  There's more, but if you click on the link at the start of this paragraph, you can read the rest.

So here is what it looks like in PET:

Fig. 1  FDG PET imaging of a patient with Takayasu arteritis.  Abnormal increased activity are identified along the brachiocephalic and proximal right and left common carotid arteries.

Fig. 2  A fused image denoting the areas of uptake with anatomical features.

Fig. 3  Sagittal fused image with uptake through the common carotid artery.

The preparation for the Takayasu arteritis scans are fairly similar to the other oncological preps that we do in the department except for the fact that we scan with the arms down, we wait for a 90 minute uptake (since the appearance of the inflamed arteries are very subtle thus maximizing the uptake time is essential) and we use an ideal body weight (IBW) calculation.  The cut off glucose measurement is around 11.0mmol/l.  This is slightly higher than the normal cut off of 9.8mmol/l for the rest of our scans.  Imaging is taken from the base of the skull to mid thigh, but 4 minutes per bed for the PET as oppose to the 3 minutes per bed with most of our oncological studies.

As you can see in Fig. 1, there is abnormal increased activity identified along the brachiocephalic and proximal right and left common carotid arteries.  There is also increased activity in the descending aorta at the L2-L3 vertebra, which I did not capture on my screen shots.  PET/CT would probably not be the first choice in terms of imaging with a suspected case of Takayasu arteritis, the more likely options would be CT angiography or MRI to examine the nature of the large vessels.