Nuc Med Clinical Pearls: The Case of Redistributed Tc-99m Sestamibi

Nuclear Pharmacists at Jubilant Radiopharma frequently receive calls from customers seeking guidance on a variety of clinical scenarios or answers to questions that arise while performing their daily work. Thanks to our Pharmacists’ specialized knowledge and expertise, they are often able to offer solutions that save the customer time and money. Dr. Christopher W. Stanton, pharmacy manager of Jubilant Radiopharma – Greater New York Pharmacy, describes the below clinical scenario involving a redistributed Tc-99m Sestamibi dose that the team helped a customer resolve.

Scenario

A customer called the pharmacy to report an altered biodistribution of Tc-99m Sestamibi, which appeared in the patient’s eye socket. Our nuclear medicine customer wondered what this could mean. He sought advice as to whether the altered biodistribution could impact safety, scan interpretation and diagnostic imaging accuracy, and asked whether something else could be going on.

Solution

Recognizing that this anomaly could be significant, the pharmacy team’s first step was to confirm whether or not altered biodistribution had actually occurred. As Tc-99m sestamibi has been shown to accumulate in several primary malignant tumors and in distant metastases, it was possible that the technologist had unintentionally detected a retinoblastoma. 

As part of our due diligence, other Jubilant Radiopharma customers who had received doses from the same lot were called to determine if they had also noticed any altered biodistribution. In addition, radiochemical quality controls were re-performed to ensure there were no signals to product performance. When nothing out of normal limits was detected, the customer was advised to wipe the patient’s eyelid and monitor hands for signs of contamination. Again, no contamination was found. 

Results

Through process of elimination, we were able to rule out environmental reasons for the altered biodistribution and, thereby, educate our nuclear medicine colleagues on possible causes of a non-cardiac image from a Tc-99m Sestamibi dose. Through this investigative process, which signaled a valid dose response rather than a handling error, pharmacy team members potentially helped with early detection of an unknown tumor in a patient. 

Clinical Pearls

In addition to tumor imaging^1,2, Tc-99m Sestamibi has been found to be a cost-effective means to help detect drug-resistance^3,5,6 in tumors. A Journal of Nuclear Medicine article⁴ provides a valuable review of the multiple benefits of Sestamibi in cancer detection. In this article, Mohan and Miles conclude that 99mTc-Sestamibi can not only accurately predict which patients with lung cancer will respond to chemotherapy, but also that it is a cost-effective means to ascertain this important treatment information. 

References 

1. AKTOLUN, CUMALI M.D., M.Sc.; BAYHAN, HIKMET M.D.; OZTURK, EMEL M.D. Better visualization of retinoblastoma metastases with Tc-99m sestamibi versus Tl-201. Clinical Nuclear Medicine. May 1995; Volume 20, Issue 5 
2. Kowalsky RJ, Falen SW, eds. Radiopharmaceuticals in Nuclear Pharmacy and Nuclear Medicine, 3rd ed. Washington, D.C.: American Pharmacists Association; 2011.
3. Nishiyama Y, Yamamoto Y, Satoh K, et al. Comparative study of Tc-99m MIBI and Tl-201 SPECT in predicting chemotherapeutic response in non-small-cell lung cancer. Clin Nucl Med. 2000;25:364-369
4. Mohan H, Miles K. Cost-Effectiveness of 99mTc-Sestamibi in Predicting Response to Chemotherapy in Patients with Lung Cancer: Systematic Review and Meta-Analysis. J Nucl Med. 2009;50:376-381  
5. Yuksel M, Cermik TF, Karlikaya C, et al. Monitoring the chemotherapeutic response in primary lung cancer using 99mTc-MIBI SPET. Eur J Nucl Med. 2001;28:799-806
6. Kao CH, Hsieh JF, Tsai SC, Ho YJ, Lee JK. Quickly predicting chemotherapy response to paclitaxel-based therapy in non-small cell lung cancer by early technetium-99m methoxyisobutylisonitrile chest single-photon-emission computer tomography. Clin Cancer Res. 2000;6:820-824