Nuclear Medicine/Molecular Imaging E-Lert

… is a service of Radiology Today. The article selections and comments are provided under the direction of C. Richard Goldfarb, MD, attending radiologist at New York Radiology Associates, PC, attending radiology chief in the division of nuclear medicine at Beth Israel Medical Center in New York City, and an associate professor of nuclear medicine at Albert Einstein College of Medicine in Bronx, NY.

1. Ekaterina Dadachova, Arturo Casadevall. Radioimmunotherapy of Infectious Diseases. Seminars in Nuclear Medicine 2009. 39(2);146-153.

An overview of antibody-labeled radiopharmaceutical agents and their potential use in localizing and treating infection.

Comment: In recent years, antibiotic therapy has been hampered by increased microbial resistance while the occurrence of infections is on the rise with new bugs afflicting those with reduced immunity. This exciting essay describes novel nuclear prescriptions for combating infectious disease similar to the use of radioimmunotherapy in oncology.

2. Selin Carkaci, Homer A. Macapinlac et al. Retrospective Study of 18F-FDG PET/CT in the Diagnosis of Inflammatory Breast Cancer: Preliminary Data. JNM 2009. 50(2); 231-238.

A small study of breast cancer staging by PET/CT shows promising results due to improved locoregional and distant metastasis detection.

Comment: Inflammatory breast cancer is aggressive and bears substantially poorer prognosis than other types with a mean 5 year survival rate of less than 40%. The 20% likelihood of distant metastases in IBC at first diagnosis in itself warrants the use of multiple investigations, including—and perhaps especially, FDG-PET/CT in initial staging.

3. Sheng-Pin Changlai, Pai-Jung Chang, et al. Biodistribution and Dosimetry of 131I in Thyroidectomy Patients Using Semiquantitative γ-Camera Imaging. Cancer Biotherapy & Radiopharmaceuticals 2008. 23(6): 759-766.

A preliminary study discusses the biodistribution of I-131 after remnant ablation of thyroid cancer, and finds that the highest absorbed doses occurred in the stomach, gastrointestinal tract, and heart wall.

Comment: Most published estimates of whole body and organ specific I-131 exposure are based on patients with intact thyroids. The increasing use of I-131 in ablative or adjuvant therapy after thyroidectomy warrants more accurate estimates of doses to organs at risk of acute adverse effects and/or late sequelae including secondary malignancy.

4. Ling-Fa Li, Shui-Hong Zhou, et al. Clinical Significance of FDG Single-Photon Emission Computed Tomography: Computed Tomography in the Diagnosis of Head and Neck Cancers and Study of Its Mechanism. Cancer Biotherapy & Radiopharmaceuticals 2008. 23(6): 701-714.

Glut-1 and Glut-3 expression has been suggested to be correlated with FDG uptake, and this study examines both the capability of FDG-SPECT/CT to diagnose and localize head and neck cancer, as well as the correlation between Glut-1 and Glut-3 with FDG uptake.

Comment: FDG PET/CT is routinely used in the evaluation of head and neck cancers but scarce data is available for FDG SPECT/CT. The growing popularity and availability of SPECT/CT warrants comparative studies such as this one that confirms its additive value compared to anatomic imaging alone. The reduced cost of SPECT vs. PET equipment facilitates its availability not only in poorer countries but also in smaller centers where SPECT is routinely used.

5. Egesta Lopci, Roberta Burnelli, et al.18F-FDG PET in Pediatric Lymphomas: A Comparison with Conventional Imaging. Cancer Biotherapy & Radiopharmaceuticals 2008. 23(6): 681-690.

An examination of the suitability of FDG PET to detect lymphoma determines a high specificity and sensitivity, but does note false-positives in 10% of patients.

Comment: FDG-PET is well established in the management of adult lymphoma. But children are not simply “little adults” which is why Pediatrics is its own specialty. Lymphoma in particular behaves differently in children with fortunately a better overall prognosis. Not fortunately, though, the chemotherapy for children is tough for them to handle. This optimistic report suggests that FDG may enhance our ability to assess the need for, and response to, potentially toxic and/or ineffective treatment. Also earlier detection of recurrence and more accurate initial staging substantially improves prognosis.

6. Zakavi, Seyed Rasoul; Mousavi, Zohreh, et al. Comparison of four different protocols of I-131 therapy for treating single toxic thyroid nodule. Nuclear Medicine Communications 2009. 30(2); 169-175.

A prospective study of 97 patients treated for toxic thyroid adenoma finds that a high-dose protocol of I-131 is preferable for elderly patients, while younger patients should have a calculated dose of radioiodine.

Comment: Due to the very high recurrence rate in autonomous toxic nodule following antithyroid drug therapy—and even following surgical excision, I-131 is clearly the treatment of choice. The problem has been that no consensus exists regarding the optimal dosing. Most give higher doses than for diffuse toxic goiter but without precision and more by hunch than by conviction. This prospective study is encouraging in that it confirms the hunch and increases the precision of I-131 treatment of toxic nodule.

7. Chen, Dan Yuna, Jing, Jin, et al. Comparison of the long-term efficacy of low dose 131I versus antithyroid drugs in the treatment of hyperthyroidism. Nuclear Medicine Communications 2009. 30(2); 160-168.

A long-term study pits low dose I-131 against antithyroid drug therapy in the treatment of hyperthyroidism, and finds that I-131 has a higher long-term remission rate than ATD.

Comment: I strongly recommend a read of this paper. If its results are transferable to a non-Chinese population, then the authors’ rigorous dose calculation method is worth emulating. And that method is described in simple, clear terms that make it quite feasible to all.

8. Félix-Nicolas Roy, Sylvain Beaulieu, et al. Impact of Intravenous Insulin on 18F-FDG PET in Diabetic Cancer Patients. JNM 2009. 50(2); 178-183.

Intravenous administration approximately 1 hour before FDG injection reduced hyperglycemia in diabetic patients, with acceptable biodistribution of the radiopharmaceutical in three quarters of the patients in this study.

Comment: Hyperglycemia is assumed to lower the sensitivity of FDG-PET.
Guidelines call for blood glucose to be no higher than 126 mg/dL when FDG is injected. In diabetic patients—based on scarce research data—the practice is to administer insulin in order to reduce the hyperglycemia but there is some concern that insulin itself would alter biodistribution of FDG and reduce tumor uptake. This paper provides support for the use of insulin to reduce hyperglycemia prior to FDG injection and offers pointers on how to identify a suboptimal study.

9. Eric Laffon, Anne-Laure Cazeau, et al. The Effect of Renal Failure on 18F-FDG Uptake: A Theoretic Assessment. Journal of Nuclear Medicine Technology 2008. 36(4); 200-202.

The imaging protocol this study proposes for patients with arbitrary renal failure includes delayed image acquisition and reduced injected tracer.

Comment: Kidney function is a major concern in the CT contrast world where renal failure is a contraindication and iodinated contrast is unfortunately an occasional cause of renal dysfunction. Scintigraphy studies are no threat to the kidneys but altered renal function threatens accurate interpretation and can expose staff and patients to greater radiation exposure. This clever study offers a possible solution.

10. Suvranu Ganguli, Marc Camacho, et al. Preparing First-Year Radiology Residents and Assessing Their Readiness for On-Call Responsibilities: Results Over 5 Years. AJR 2009. 192;539-544.

A study demonstrates that upper level collegues out-performed first year residents in emergency radiology protocols.

Comment: Many medical centers are literally 2 different—almost unrecognizable—personalities; the after hours staff largely on the trainee level. These radiology trainees have come under increasing pressure for perfection in the current era of “night owl” teleradiology using attendings in other time zones or other countries.