The elusive gallbladder

30 minute of the hepatobiliary study, pre-CCK administration. The question was raised if this was the gallbladder or distended duct.  An additional image was obtained in the LAO view to further determine if this was the gallbladder..

After review of the LAO view (5 minute acquisition time) it was decided that this looked like the gallbladder, so the CCK study could begin.

Using the same position as the previous LAO image, the computer was set-up for CCK infusion and  acquisition. As the study was started it was noted that the gallbladder appeared.

In review the structure that was originally thought to be the gallbladder was most likely distended common bile duct.

Thanks to Larisa Levran

PET scan mis-alignment

This patient was scheduled for a PETCT with Diagnostic CT of the chest. The patient was positioned on the scanner, the tomogram was acquired followed by the whole body CT scan. Contrast was injected and the diagnostic CT of the chest was acquired. Even though the patient had used the rest room prior to the scan, she indicated she had to go again.

When the patient was repositioned on the scan table, a new topogram and whole body scan were entered into the original set-up (Siemens Biography 16, we copied and pasted the newer acquisition into the original acquisition page).

A new topogram and CT whole body were re-acquired followed by the whole body PET scan. The computer preformed the attenuation corrected image, with the above results, showing lack of data in the right half of the brain.

Review of the uncorrected data reveal that the data was good (below), which did not give any indication as to why right portion of the brain should be lacking in counts.

The study was re-processed manually using the second whole body CT data with the corrected results shown below. The image demonstrates complete uptake by the brain when compared with the first image.

The automatic processing selected the data from the first whole body CT acquired and not the second scan acquired prior to the PET scan. The differences in patient position from the first CT scan to the second CT scan is evident in the first set of PET processed data..

Iterative reconstruction v filtered backprojection

Iterative reconstruction (IR) is the primary method of reconstruction of SPECT data. However there are some drawbacks to using this process.

IR utilizes the collected data and breaks it down into pixels and then treat each pixel value as an unknown. Using an algorithm values can be assigned to each pixel, permitting the emission and detection data to be accurately modeled.

Noise acquired during the SPECT acquisition, in the absence of attenuation correction, is constant across the reconstructed field. This eliminates streaking artifact in the image and provides a visually superior image to filtered back projection (FB) processing.

The above image of a bone whole body spect, processed with iterative reconstruction shows a large photopenic area where the femurs should be. Using IR the pixel values of a low count area may be treated as background or noise in comparison to the adjoining pixels...

Filtered backprojection, takes the acquired data and fills in the spaces between the projections (azimuths) to create a completed 360-degree image. Although this completes the image it does create blurring, to which filters can be applied for an improved appearance. Unlike IR processing, FB does contain noise and background activity..

Recprocessing the acquired data with filtered back projection shows a complete if not more favorable image. Note the noise or "rays" of activity surrounding the scan, especially around the bladder activity...

References:
1. Image reconstruction - a tutorial, G.L. Zeng, Computerized Medical Imaging and Graphics 2001
2. An introduction to iterative reconstruction, B Hutton
3. Filtering in SPECT image reconstruction, M. Lyra and A. Ploussi, International Journal of Biomedical Imaging,  April 2011

Dilated Common Bile Duct

When blockages can occur in the  bile ducts, they can become dilated. These blockages can be associated with gall stones or cholangiocarcinomas. Dilated ducts are also common in patients following cholecystecomy, which may increase in size over time. However this is usually of no significance by itself, unless there are other findings such as pancreatitis or elevated liver functions.

The non-contrast CT images above demonstrated an incidental finding of dilated common bile duct (yellow outline) in a female with a history of cholecystectomy. Hepatobiliary scan requested to determine duct patency.

4 mCi Tc Choletec was administered intravenously and imaging was completed in the anterior projection for 1 hour. The images demonstrate normal  passage of the Tc Choletec through the common bile duct and into the small intestine, demonstrating no blockage in the common bile duct.

Reference image - Gallbladder (green) liver (orange) kidneys (light blue) aorta (red) inferior vena cava (blue)

Reference: Are dilating bile ducts a cause for concern?  ML Wilkinson, Gut 1999;45:637-638

Empathy: The Human Connection to Patient Care

Saw this as part of a patient care presentation at work. A great video, from the Cleveland Clinic, to attempt understand everything that evolves around us each day at work and in life in general...

Non-osseous abnormalities on bone imaging

I have always found non-osseous uptake of skeletal imaging agents to be of interest. In 2003 the Journal of Nuclear Medicine Technology published an excellent article on non-osseous abnormalities. During my years of teaching, students have brought in many examples which I wish to share...

In the area of altered biodistribution, whether due to faulty preparation or pharmaceutical interference:

Free technetium due to the presence of air in the container during preparation will lead to increased uptake of unbound technetium in the stomach, gastrointestinal tract, thyroid and salivary glands...

It was noted in the article that drug interaction with diphosphonates used in treatment of osteoporosis can lead to decreased skeletal uptake.

Male on hemodialysis, with a complaint of back pain. Findings include decreased skeletal uptake of the radiopharmaceutical. The patient medical history includes administration of PhosLo (calcium acetate tablets) 3-times a day with meals indicated for patients with hyperphosphatemia. The retention of phosphates in patients with renal insufficiency plays a role in causing secondary hyperparathyroidism. This scan was compared to another patient scanned with radiopharmaceutical from the same bath to verify this was not associated with poor radiopharmaceutical preparation. Due to the patient's condition his attending physician would not take him off the PhosLo for a repeat scan...

Uptake related to the urinary system, is the most common finding of non-osseous uptake. Findings include: dilated, obstructed ureters, hydronephrosis, renal cysts:

80-y female, history of melanoma, complains of back pain. Findings include a mild right side hydronephrosis, with a dilated ureter noted in the pelvis...

91-y female, fell 3 days prior to scan, complains of left hip pain. Findings include marked hydronephrosis of both kidneys with dilatation of both ureters. Possible obstructive uropathy near the urinary bladder...

25-y male, with history of right renal abscess. Skeletal imaging was ordered for a complaint of right side flank pain to rule out osteomyelitis. Findings include a photon deficient 4cm area in the upper pole of the right kidney consistent with a cysts, tumor or abscess...

38-y female with a history of right lung carcinoma. Findings include poorly defined uptake at the areas superior to both kidneys, suggestive of metastatic disease in the adrenal glands...

Soft tissue uptake may be found in various areas due to soft tissue calcification, which may point to specific pathology:

51-y female with a history of breast cancer. Findings include mild diffuse uptake in the liver, of uncertain clinical significance. The likelihood of interference of additional imaging procedures was reviewed. The patient did not have a prior liver scan, which would have been performed by calculation on Sunday when the department was closed for routine imaging. Gallium-67 for soft tissue imaging would present with considerable background activity. The pattern of uptake is not suggestive of hepatic metastatic disease, but may suggest necrosis or microcalcification...

Elderly female fell out of bed onto her left side, complains of left hip pain. Findings include increased cardiac uptake as well as uptake in several left ribs suggestive of cardiac contusion and rib fractures related to trauma...

76-y male with a history of right nephrectomy, on hemodialysis, complains of low back pain. Findings include cardiac uptake related to calcification of the pericardium, which was seen on a recent CT of the chest. This may be an indication of metastatic calcification, which can be seen in secondary parathyroid hyperplasia...

46-y male with a recent finding of multiple myeloma. Findings include intense uptake in the region of the myocardium, most likely secondary to calcified pericarditis, however diffuse myocardial infarction may also have this appearance...

Female with documented history of hypercalcemia. Findings include diffuse uptake of the the radiopharmaceutical in both lungs. This pattern of uptake has been implicated with hypercalcemia and related to metastatic calcification...

Thanks to Heny Shah, Dolores Ambrosy, Corrine Zenkel, 

WB Skeletal Imaging - motion artifact

Whole body bone scan obtained 2 hours following the intravenous injection of Tc99m MDP.

Older cameras used to perform whole body images by scanning at the right side of the body head-to-toe, moving the table and scanning the left side of the body toe-to-head. This often produced a zipper line done the middle of the body where the images were joined. If the patient moved or the camera and table were not properly aligned the images could result in separation of the images or mis-registration.

Newer systems have the ability for single-pass imaging, which eliminates the zipper and mis-registration problems. The single-pass technique although does not always allow for inclusion of the patients arms in the field of view.

On this particular image the patient noticeably moved their head from right to left resulting in the alien feature of a twin lobed cranium.

The practice of this institution was to perform a whole body posterior image with spot shots of the anterior skull chest, abdomen, and pelvis. 

Although this is older technology, newer camera do not require a double pass for the whole body image, I have always enjoyed the "alien" presence in this image..