Sarcoid versus Scleroderma

I always get mixed up when it comes to sarcoids and sclerodermas when written on a requisition.  Currently we perform imaging on these patients to help the clinicians to determine the extent of their patient's disease, but I still get confused as to the nature of the disease and their processes.  So this portion of the blog is partly to help me and anyone out there that are in the same position.  I have tried to put this into a chart format, but it doesn't translate well into the blog.

Sarcoid:
This is an inflammatory disease that can potentially affect multiple organs within the body.  It most often starts within the lungs or lymph nodes, but it does not limit it self to these areas.  The inflammation (sarcoidosis) is not necessarily caused by an autoimmune response, since this is not an autoimmune disease, but the cause of this inflammation is uncertain.  The most distinguishing feature about sarcoids is that they deposit granulomas (microscopic lumps of inflammation).  They sometimes clear up on their own or they can become fibrotic if they remain in the body if they do not heal.

The most famous entertainer to die from sarcoidosis was Bernie Mac.  His condition was primarily localized to his lungs, but sarcoids, like I mentioned before can affect any organ.  Here at our facility we image and follow these patients when they become part of the CADRE study.  CADRE represents the Cardiac FDG-PET Registry Study.  As part of the cardiac program, we look at the extent of their disease via a whole body PET/CT, which we append to their Tc-99m myocardial perfusion studies.  Along with the whole body PET/CT, we will perform a quick FDG viability study of their heart while in the department.  Most of these patients have their cardiac workup prior to coming to PET.  Approximately 25% of all sarcoids involve the heart, and about 13-25% of all sarcoids deaths are related to cardiac insufficiencies such as heart failure, ventricular tachyarythmia or conduction disturbances.

Fig. 1  Extensive uptake of FDG within the thorax, liver, spleen and both kidneys, correlating with the patients known sarcoidosis.

We also perform gallium-67 whole body imaging to localize the areas of inflammation, in particular the lungs.  But quite honestly, we do not perform these routinely, and having said that, I don't think I have ever seen one that was positive.

UPDATE January 2, 2012:  I will take back that last comment about not seeing a positive gallium scan for sarcoidosis.  The image below was taken 48 hours post Ga-67 injection.  A whole body gallium scan was performed and there was uptake within the lungs consistent with sarcoidosis.

Fig. 2  Uptake in the hilum and the lungs, consistent with sarcoidosis

Scleroderma:
This is the result of inflammation in connective tissue featuring the formation of scar tissue (fibrosis) in the skin and organs of the body.  Scleroderma is an autoimmune disease, as the result of an overactive immune system.  They have specific antibody markers such as ANA, anticentromere or antitopoismerase in their blood stream which suggests autoimmunity.

We perform gallium imaging for scleroderma, but rarely.  I have not come across this condition with regards to the patient's history for PET/CT imaging.... yet.

I do not have any images to show from our facility and there isn't much on the web either.

I-131 Uptake in Teratoma

Fig 1 WBI scan performed 10 days post 125mCi treatment of I-131 therapy for thyroid Ca.

A whole body iodine scan was performed 10 days post I-131 therapy for a patient who was diagnosed with thyroid cancer.  For the most part the scan seems relatively normal, with residual activity within the thyroid bed and salivary glands.  The liver is within normal limits.  However in the lower left hemipelvis, there appears to be an increased I-131 avidity.  Of course to investigate this further we performed a SPECT/CT.

Above is the MIP for the SPECT (doesn't look like much), but when fused with the CT, the following is presented.

Fig. 2  Sagittal section of the I-131 activity.  The fat containing mass measures approximately 

5.8 x 3.3 cm.

Fig. 3  Coronal section, noting the uptake in the lower left hemipelvis.

The I-131 fat containing lesion within the left pelvis is in keeping with a left ovarian teratoma.  These are also know as an ovarian dermoids.  Most dermoids/teratomas are benign, and they contain a mix bag of mature and immature tissue such as skin, hair, thyroid tissue, sweat glands, blood, cartilage and even teeth!  Generally the appearance of fat within the teratoma along with an irregular component of coarse calcifications help to distinguish these entities when imaging with CT and MRI.  The gross anatomy is quite interesting to look at, since they are varied in nature with respect to their appearance and construction.

PET Melanoma

Needless to say this patient presented to our department with late stage melanoma.  A new lung nodule had presented itself on the right lung from a chest x-ray and a PET/CT study was ordered and performed according to departmental protocol.

The patient has had extensive surgery to remove the melanoma from the lower back, along with excision of lymph nodes.  The patient also had a previous bout Bowen's disease over the right breast with further metastasis to the left axillary nodes.  Upon follow up with the medical oncologist, post surgery, a chest x-ray was performed and it noted a right solitary lung nodule.  

The PET/CT was performed and the following images demonstrate extensive and diffuse metabolically active metastatic adenopathy, as well as skeletal, pulmonary, liver, splenic and small bowel metastases.

Fig. 1  Multiple foci of metabolic activity of F18-FDG

Fig. 2  Sagittal fused image of the patient, noting multiple F18 FDG uptake in the spine

At our facility for indications of single pulmonary nodule (SPN) or for non small cell carcinoma (NSCLC) we normally scan from the top of the head to mid thigh.  If they have had a previous MRI of the head to determine brain metastases, then we will scan from the base of the skull to mid thigh.  However in this case, the patient has had a previous history of melanoma, we decided to scan from the top of the head to their feet.  This is our normal protocol with regards to melanoma patients.  Basically we performed our melanoma protocol on the patient referred for a lung indication.  

Generally it takes about 30-35 minutes to scan from the top of the head to their feet depending on the height of the patient.  Considering that our PET/CT is an old Seimens Biograph with a 2 slice CT, it does take up a bit of time with respect to the CT acquisition.  In addition to this, we do not have the the time of flight (ToF) capabilities to decrease our acquisition times of our PET.   However, we are replacing our Biograph with a new machine, since the 2 slice Biograph has come to the end of life for servicing.  Anyone interested in a PET/CT unit for training or for a back up?

Normal Uptake on WBI

Fig. 1  Whole body iodine, 10 days post administration of a therapeutic dose of I-131.

Whole body iodine (WBI) imaging was performed on a patient who was administered 3.7GBq of I-131 ten days prior for papillary carcinoma.  A total thyroidectomy was also performed as part of the treatment process earlier in the year.

For the most part the thyroid bed was unremarkable as well as the rest of the image, except for a focal uptake in the right upper quadrant.  Generally the technologists are fairly cautious at our facility, since a metastatic survey was being performed, a SPECT/CT of the area was also included in the study.

Fig. 2 Coronal section of the SPECT/CT, noting the uptake within the liver.  Most likely being gallbladder uptake of the I-131.

Fig. 3  Transaxial CT used in conjuction with the SPECT to localise the I-131 uptake.

Fig. 4  Fused transaxial SPECT/CT, confirming the uptake of the radioactive iodine is inside  the gallbladder.

Why is this interesting?  Well for one thing, this is something that we do not normally see on our WBI images.  Normally we see diffuse liver uptake in this area,  but it is not totally uncommon to visualise the gallbladder.  This is well documented in the literature and the article does discuss some possibilities of what can potentially cause this normal uptake.  Conditions such as cholecystitis, hypokinetic gallbladder function due to stones or an abnormal gallbladder morphology are just some of the potential reasons.  Most often an ultrasound is ordered to confirm or correlate if there are any underlying issues that may be involved with the gallbladder.

Bottomline, gallbladder uptake is normal.  It is not commonly seen, but from a technical perspective we would rather be "safe than sorry" by performing extra imaging such as a SPECT/CT.  Iodine is not the best isotopes to image with and with high energy collimators, it would have been tough to identify based on static images.

Therasphere Part Deux

Our first patient, who has a long standing history of hepatocellular carcinoma (HCC), was excluded as a surgical candidate to remove the tumour in the right lobe of the liver because the patient suffers from portal hypertension and low platelets.  The alternative consideration was for transcatheter arterial chemoembolization (TACE) to treat the tumour,  however somehow this patient ended up in the trial study of Yittrium-90 Theraspheres at our facility (click on link for further reading)

A mesenteric angiography and embolization was performed as the first step of the selective internal radiation therapy.  The reasoning is to ensure the blood flow localizes into the tumour site while sparing normal healthy sites when the Y-90 is delivered.   The mircocatheters where inserted through the right femoral artery and threaded to the right hepatic and left hepatic arteries for the arteriography.  The right gastric artery, which arose from proximal left hepatic artery, was embolized with vortex coils.  Furthermore the gastroduodenal artery was emoblized as well, leaving patent the common hepatic artery, the left and right hepatic arteries.

Fig. 1  Infusion of contrast through the right hepatic artery.  Note the embolization coils below.

Fig. 2  Infusion of contrast through the right hepatic artery, outlining the tumour in the right lobe.

Fig. 3  The right lobe tumour is now fully visualized, with limited shunting.  However there is still extraneous vascularity.  Thus the lung shut fraction is calculated to quantitate the amount.

After the embolization process, Tc-99m MAA was injected through the microcatheter for the lung shunt study.  After the injection, the patient was stabilzed for transport to Nuclear Medicine, and the following images were taken.

Fig. 4  Anterior and posterior images were taken to determine any major shunting of blood to the lungs or stomach.

Fig.  5  Regions of interest were drawn over the lungs and liver and a geometric mean was calculated to determine the lung shunt fraction (LSF).

Lung shunt fraction was calculated to be 3.0%.  There is no cut off with regards to the LSF value to be excluded from the treatment.  However it is the discretion of the interventional radiologist who will be administering the Y-90 to determine the patient's inclusion within the treatment study.

Two weeks after the initial angiography and embolization, the Y-90 theraspheres were adminstered.  Based on the size and volume of the tumour which the interventional radiologist calculated prior to the administration, we wanted to give approximately 2.5Gbq of Y-90 to deliver 120Gy to the tumour site.

Nordion which supplies the theraspheres, has an excel worksheet to help with the ordering of the Y-90 dose to ensure the proper calibration of the actual dose.
In the end, the amount that we calculated (approximation) of the dose delivered to the tumour site was about 2.49GBq, based on a 1.7% residual activity remaining in the Y-90 administration vial.  Overall the tumour received 120.7Gy with the lungs receiving approximately 3.73Gy, based on the LSF value.

Having worked through our first patient it is important to address the fact that most Nuclear Medicine technologists are accustomed to working with radioactive materials.  However the interventional radiology (IR) technologists and some IR doctors do not.  The dose rate is quite high with respect to the Y-90 vial.... but we normally do not tell them how high it really is.  Thus it is a good idea that you get them on board with respect to working with radioactive materials and how to handle these materials without causing too much of a mess.  The reason why, is that they are most likely going to set up the Y-90 administration set, since they have much more experience than Nuclear Medicine technologists in a sterile field.  Plus it will be the IR doctors (at least at our site), that will be injecting the Y-90.

Fig. 6  An unassembled administration set.  Everything is performed in a sterile field.  I will endeavour to update this image, once everything is connected together, when our next patient arrives.  Which should be in 2 weeks time.