GNYCSNM Atlantic City 2013!!

Bone Scan - Post Reclast Therapy

Reclast is marketed by Novartis, was was approved by the FDA for treatment of Paget's Disease in 2007. Administered by infusion, the main ingredient, zoledronioc acid, is also marketed by Novartis as Zometa for use in the treatment of skeletal fractures in patients with cancers such as multiple myeloma and prostate. It has also been used to treat osteoporosis. For the treatment of Paget's patients recieve a single dose, annually. Results of studies for Reclast were published in the Sep 1, 2005 issue of the New England Journal of Medicine.

The cause of Paget's Disease is unknown. The disease causes an abnormal breakdown of bone tissue, followed by abnormal bone formation. The new bone is enlarged but weaker. The disease often effects the bones of the arms, collarbones, legs, pelvis, spine and skull.

2011

2013

The above patient studies were obtained at 3 hours following the injection of 25 mCi Tc MDP. Whole body bone scans with post void images of the pelvis were obtained. The study from 2013 demonstrates marked decreased activity in the right hemipelvis, following Reclast therapy, as compared to the study from 2011. 

Sentinel Node Imaging

Sentinel Node imaging was introduced it served as a means to reduce the number of lymph nodes excised during surgery, thereby reducing the morbidity rate in women undergoing the procedure. The concept is to establish the path that cancerous cells may take along the lymphatic channels, allowing for metastic cells to travel to other organs.

Debate has often been raised as to whether there is a need for imaging or not. Surgeons have requested patients receive the injection and go right to surgery...

The proceeding example demonstrates a reason to image the patient, which is first and foremost to ensure the injection is good and the materials is traveling through the lymphatic channels. But secondary to determine where the radiopharmaceutical is traveling.

This patient presents with right breast cancer, pre-lumpectomy and lymph node dissection. The patient was positioned in a right oblique position and injected with 500 uCi Tc99m sulfa colloid with Lidocaine by subcutaneous injection to the right of the nipple. When the patient was placed under the camera it was noted that there were lymphatic tracks above and below the injection site.

On the next image a lead blocker was placed over the injection site and imaging was continued at 2 minute intervals.

Although the physician was confident in the location of the sentinel node in the right axilla, he wanted confirmation that the lower track was not going to a lymph node but as altered due to the patient's previous surgery in the lower portion of the right breast. The patient was placed in the right lateral position and the right axillary node is easily identified and the lower track appears to remain in the breast tissue. No lead placed over injection site.

To further define the activity in the right breast, the patient was placed in an oblique position with a wedge under the left shoulder and imaged from the right posterior oblique position. This view allows the breast to move away from the patient's torso to further show the activity below the injection site (blue dot at site of lead blocker) is confirmed to be in the breast tissue.

As the radiologist put it, this became an exercise in obliques to best find the view that would confirm the activity was indeed in the breast and not traveling to a lymph node.

Whole Body Bone SPECT

Recently we starting looking at whole body bone spect imaging for metastatic evaluation. Metastatic disease in the vertebral bodies can be difficult to detect on planar whole body imaging, and an abnormal finding does not always mean metastatic disease. It is also difficult to detect small abnormalities in the thoracic vertebrae.1 

In order to acquire a whole body bone spect in an acceptable time frame, the time per bed has to be reduced. Studies were performed and determined that a bone spect can be acquired in as little as 5 minutes and still be acceptable as compared to planar imaging.2

Filtered back projection - the most commonly used method of image reconstruction. the back projection assigns values in the projection to all points along the line of acquisition through the image plane from which it is acquired. This can create an star artifact  consisting of radial lines at the edge of the object, to which a filter is then applied to reduce this artifact.3

Iterative reconstruction - is a more computer intensive program, which uses the original projections and models of the acquisition to predict areconstruction. The predicted projections are used to modify the recontstruction. In the OSEM method the projection data are ordered into subsets. The advantage of this is an increase in computer processing speed.3

Iterative reconstruction has proven to be superior to count poor data, which would create excessive noise from the radial lines when filtered back projection is applied. Our data was acquired at 6 secs per view, 64 views for a 12 minute acquisition time, compared to our standard SPECT acquisition time of 40 minutes.

When the initial study was reviewed it was noted that some problems existed. The first bed (patient head) looked good but the rest of the body offered excessive background noise, especially around the bladder. It was discovered that the iterative reconstruction was applied to the first bed, while filtered back projection had been applied to the remainder of the study.

Whole body coronal slices processed with filtered back projection

After re-processing the data with iterative reconstruction applied to all of the beds we noted another problem. The right half of the skeleton has a brighter, crisper look. It was then discovered that the data selector for processing was for 180 degrees. 

Reprocessed coronal slices with iterative reconstruction, but 180 degree processing

We adjusted the processing protocol to used the 360 degree method and re-processed the data again. This time the study came out with excellent results. (I never knew the system could process half a study?!)

Processing page, applying 5 separate acquisitions into one study

References:

1 - Do short-time SPECT images of bone scintigraphy improve the diagnostic value in the evaluation of solitary lesions in the thoracic spine in patients with extra-skeletal malignancies? 

Kobayashi, et al. Annals of Nuclear Medcine vol 19 No 7, p557-566, 2005.

2 - What is the optimal minimum whole body bone SPECT scan duration that can replace planar scintigraphy? 

Mawlawi, et al, The Journal of Nuclear Medicine vol 48 supplement 2, p120, 2007.

3 - Nuclear Medicine and PET/CT, technology and Techniques.

Christian and Watersum-Rich, Mosby Elevier

Stress Fracture - Shin Splints

A stress fracture is an overuse injury, one of the most common injuries in sports, especially the weight bearing bones of the lower extremities.

MRI has surpassed skeletal scintigraphy showing equal sensitivity, but a higher specificity, while providing improved anatomical detail.  However, there is still reason for obtaining a three phase bone scan for lower extremity trauma when MRI may be inconclusive or for patients who can not handle the MRI scan.

Often a physician will request a 3 phase bone scan for lower leg pain to determine if the pain in a patient's lower extremity is either a stress fracture or trauma, or shin splints (medial tibial stress syndrome).

A stress fracture often occurs as the result of an increasing amount or intensity of pressure during an activity more rapidly than the bone structure can manage. They may also be caused by impact (rapid change in surface hardness), improper equipment (poor foot support in a shoe) and increased physical stress.1

The stress fracture is  a small crack in the bone without displacement. The associated symptom is pain, which subsides with rest.

Delayed skeletal images of a young jogger complaining of lower extremity pain while running. Top images show lateral and medial images, white the lower images show anterior and posterior images of the lower extremities. all views demonstrate a focal area of uptake in the left tibia, consistent with a stress fracture. The area correlated with the patient's focus of pain.

On a 3 phase bone scan the dynamic flow with have increased uptake at the site of injury. The second phase (blood pool, soft tissue) will also have increased uptake associated with edema around the injured site.

The 3rd phase (skeletal image) will again demonstrate increased focal uptake at the site associated with the patient's pain.

The dynamic images and soft tissue phase (not shown) demonstrated no abnormal uptake or early osseous localization.

Anterior delayed image - young female athlete complaining of lower extremity pain for 6 months. MRI was inconclusive for stress fracture, but positive for a stress injury.

Right lateral and left medial image demonstrates linear uptake along the tibial shaft consistent with 

shin splints. No evidence of fracture.

The shin splint is an inflammation of the muscle, tendons and bone tissue around the tibia, usually along the inner border of the tibia where the muscle attaches to the bone. Shin splints may be the result of improper footwear, increase in workload on the lower extremities, changes in surface conditions. All the same causes as a possible stress fracture.

The patient complaint is pain, which may be associated with mild swelling, which subsides with rest.

On a 3 phase bone scan their may be some activity associated with edema on the flow or soft tissue phases. However the delayed skeletal image will not have a focal point of activity, but increased uptake seen along the tibia.

An advantage of utilizing the bone scan over MRI is the ability to image the whole body following injection. Keep in mind that patients complaining of lower extremity pain may have associated hip pain.

Abnormal I-131 case study

Examination: Whole Body Iodine Scan

Clinical Information: 79 year old female with prior history of thyroid cancer

Following thyrogen stimulation performed according to standard protocol. 4.10 mCi I-131 was administered to the patient orally. At 48 hours after radiopharmaceutical administration, anterior and posterior whole body images were acquired along with with anterior and posterior images of the head, neck, thorax, abdomen, and pelvis.

The study demonstrates increased activity in the mediastinum and the two foci of increased activity in the right abdomen. Mediastinal activity appears abnormal and is most concerning for recurrent disease. Activity in the abdomen may be physiologic. For these regions, a chest, abdomen and pelvic CT is advised for fursther investigation.

The calculated uptake at the level of the thyroid bed is 0.4%. No focal site of abnormal increased activity is seen at this level on the acquired images.

IMPRESSION:

Abnormal whole body iodine scan with increased activity in the mediastinum that is most concerning for recurrent disease. Additional sites of uptake are noted in the right abdomen but this may be physiologic. CT scan of the chest, abdomen, and pelvis is advised for further investigation.

END IMPRESSION

Abnormal Parathyroid Scan

FINAL REPORT:

Examination: Nuclear Medicine parathyroid study

Clinical Indication: 79 year old female with hyperparathyroidism

Technique: After the intravenous administration of 24.2 mCi of Technetium 99m labeled sestamibi. Anterior planar imaging over the neck and upper chest was performed at 15 minutes and at three hous. SPECT imaging was also performed.

Findings: Physiologic distribution of radiotracer is seen. There is a focus of activity within the mid pole of the right thyroid consistent with parathyroid adenoma.

Impression:

Parathyroid adenoma at the mid pole of the right thyroid

END IMPRESSION