Image fusion, lung cancer, AMIDE

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In the old days before PET/CT, we did manly image fusion. We got separate dicom data from modalities thousands of miles apart and we tortured each voxel until they fit together as the fused image. It was fun. Now everything is done for you with PET/CT and excellent software like MIM. But every once and a while there is a rogue study. You get a stand alone PET scan from some outside site and a CT from somewhere else. What do you do?

Amide courtesy of Andy Loening at Sourceforge (amide.sourceforge.net) is a great open source software package for image fusion. It is available for Win32, Linux and MAC OSX (with some tweaking with x11 and fink). It is intuitive and robust. If you read PET from a standalone scanner or want to fuse PET/CT data to another (contrast enhanced?) CT or MRI this is an excellent option. Above is an example of a study from a standalone PET fused to a contrast enhanced CT from a different institution. There is a mass in the left hilum obstructing an upper lobe bronchus and causing post obstructive pneumonia. Fusion was performed with Amide.

This has me thinking that we should be performing fusion SPECT more often. We don't have a hybrid SPECT /CT camera and I doubt we will for some time, but Amide is an easy tool to use and won't add that much time for complex cases.

PET / CT Recurrent Laryngeal Carcinoma

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PET / CT has a greater sensitivity and specificity for detection of regional metastatic adenopathy for head and neck tumors than contrast enhanced CT. More importantly PET changes the course of management in patients with head and neck Ca in 33% of the cases where it is performed. It is also more sensitive and specific than CT for detection of local recurrence. There may be a role for PET in evaluating response to therapy for head and neck tumors but this is still developing. Remember many areas of normal FDG uptake are found in the head and neck including: Palatine, faucil and retropharyngeal tonsilar tissue, parotid, sub lingual and submandibular glands, strap muscles and the vocal cords.

Follicular Cell Lymphoma of the Duodenum

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This is a volume rendered PET/CT. Follicular cell extranodal lymphoma is rare in the duodenum where MALT would be more common. Follicular cell NHL is the most common indolent lymphoma and patients may go for years with no need of treatment. These tumors bear a chromasomal translocation which activates the bcl 2 gene. This protein blocks apoptosis aiding in cellular proliferation. Remember to be a cancer you not only have to proliferate, you have to circumvent cell death.

UCSF Womens Imaging Conference-Post Menopausal Bleeding and US

This slide from a lecture by Dr Ruth Goldstein is an elloquent summary of her talk on ultrasound and post menopausal bleeding. We don't know what endometrial thickness threshold to use in post menopausal women who are not bleeding but >99% will be normal with a thickness less than 8mm.

UCSF Womens Imaging Conference

Just returned from the UCSF Womens Imaging conference. Overall I would rate the meeting an 8/10. I will post one key concept from each of the 5 days of the conference over the next several entries.

Klippel Trenaunay Syndrome

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Clinical triad of port wine nevus (hemangioma), lower extremity swelling and varicose veins. A congenital malformation of vascular and lymphatic structures usually in the lower extremities. Pateints develope lower extremity enlargement. May develope large lymphangiomas and hemangiomas.

Image A and D: Coronal and axial T2 fat supressed MRI of lower extremities in a 14m old male infant. Note the large perineal lymphatic mass extending upinto the pelvis. Also near the knees there are other vascular / lymphatic malformations.

Image B: Image fusion of contrast MRA with conventional T2 MRI in volume rendering. You can now see the full exrtent of the vascular / lymphatic malformations in 3D with ther relationship to the arteries. Note the limited visualization of lower extremity arteries in the left calf. Patients with KT syndrome can have arterial abnormalities including atresias in the lower extremities.

Image D: Fusion of MR venogram with T2 coronal images in volume rendering. Tee entire deep venous system has been replaced by extensive collaterals. The large lateral venous channels in the thighs are called Trenaunay veins.

Hangmans fracture 3D VR CT

Classic imaging findings for a Hangmans fracture of C2. The fractures plane extends from the posterior body of C2 into the posterior arch, in ths case through the pedicles. The fracture is unstable but often there is no initial cord injury since the fracture actually widens the canal. This fracture occurs with forced flexion, like that which occurs when the knot of a hangmans noose forces the chin up (hence the name).