SNM Annual Meeting: research highlights

Radioactive patch heals skin cancer
A radioactive skin patch that can safely and successfully treat basal cell carcinoma was described by Priyanka Gupta, a nuclear medicine technologist at All India Institute of Medical Sciences in New Delhi. The skin patch contains phosphorus-32, which emits beta radiation. Gupta and colleagues used the skin patch to treat eight patients with basal cell carcinoma on the face. They applied sealed patches to the cancer sites for three hours, and then reapplied them on two subsequent days. Three months after treatment, biopsies revealed no residual malignant cancer.

The treatment had few adverse effects and resulted in minimal scarring. Importantly, the radioactive patches exhibited no toxicity. The researchers note that the limited range of phosporous-32 prevents beta radiation from reaching the bone or underlying blood vessels. "It's exciting to think that this patch can deliver treatment on an outpatient basis, with little risk of the scarring or other complications that surgery or radiotherapy present," said Gupta. "This study opens a new dimension not only for treating skin malignancies, but also for nuclear medicine therapy in general."

• Scientific paper 158: Radionuclide therapy of basal cell carcinoma with phosphorus-32 skin patch.

New approach to prostate-cancer treatment
A Swiss-German research collaboration has come up with a new treatment for prostate cancer, in particular, cancer that has recurred after surgical resection. The study showed that an alpha-particle-emitting radiopeptide, tailored to bind with prostate tumour cells, can effectively treat prostate cancer in mice. The researchers compared two radiopeptides: ²¹³Bi-DOTA-PESIN, which emits alpha particles, and beta-emitting ¹⁷⁷Lu-DOTA-PESIN. The radiopeptides were administered to two groups of mice, while a third control group received no treatment.

At the maximum tolerated dose, the alpha-emitter was significantly more effective than the beta-emitter, tripling the survival rate of the mice that received that therapy. "Our study shows that this novel form of treatment has the potential to target and destroy cancer cells with minimal damage to surrounding healthy tissue," said lead author Damian Wild, from University Hospital Basel in Switzerland. "Eventually, this therapy could give hope to some of the hardest-to-treat prostate-cancer patients and could also be applied to other types of cancer."

• Scientific paper 38: An alpha-particle emitting radiopeptide (213Bi-DOTA-PESIN) for therapy of prostate cancer.

PET/MRI targets small-animal imaging
Japanese researchers have developed a PET/MRI system that can perform whole-body imaging of small animals. The team demonstrated simultaneous PET and 0.3T MR imaging of rats from head to abdomen, with the radionuclide ¹¹C-methionine used for PET imaging and Gadoxetate for contrast-enhanced MRI. The co-registered PET/MR images were of good quality, in spite of the short half-life of ¹¹C. The images showed excellent mapping of the liver and kidneys.

"This opens up exciting new opportunities in research, in terms of increased understanding of kinetics, biodistribution of radiopharmaceuticals and, eventually, disease characteristics and physiological processes," said Mitsuaki Tatsumi, associate professor of radiology at Osaka University Graduate School of Medicine and Medical Hospital, Osaka. "Next steps include imaging body tumours in rats or mice and developing PET/MRI systems that can image people."

• Scientific paper 7: Simultaneous C-11 methionine (MET) PET and contrast-enhanced (CE) MRI rat imaging with an integrated PET/MRI system.

PET enhances dementia diagnosis accuracy
A University of Michigan (Ann Arbor, MI) study has revealed that PET scans may improve the accuracy of early dementia diagnoses for more than one in four patients. The study identified 66 patients with mild dementia or mild cognitive impairment. Participants were evaluated via standard neurological testing and anatomic brain imaging, and then diagnosed with either Alzheimer's disease, frontotemporal dementia or dementia with Lewy bodies.

The patients then underwent PET scans for amyloid deposits and dopamine nerve integrity. PET imaging changed the initial diagnosis in more than 25% of cases. The PET images revealed important disease signals that the other examinations missed, such as amyloid plaque deposits (a common indicator of Alzheimer's) and damage to dopamine nerves in Lewy body dementia. The study will track the patients for two years to confirm the accuracy of their diagnoses.

• Scientific paper 251: PET neurochemical vs. clinical phenotypes in mild-early dementia.

Multimodal imaging aids lesion classification
Brookhaven National Laboratory (Upton, NY), working in collaboration with Stony Brook University, (Stony Brook, NY), is developing a dedicated breast PET/MRI scanner. Initial results from a prototype system revealed a fusion of detailed PET and MRI images that should allow more accurate classification of breast lesions. When completed, the system will comprise a modular 3D tomographic PET scanner inserted inside a dedicated breast MRI coil (from Aurora Technologies). The modularity will enable adjustment of the scanner diameter according to patient breast size.

The combined-modality scanner will use anatomical information from the MRI to enhance the resolution provided by PET. At the same time, the predictive power of PET in identifying tumour type should overcome MRI's traditionally high false-positive rates. Based on the positive preliminary results, the researchers expect to begin testing the system shortly with breast-cancer patients.

• Scientific paper 349: Initial results from the BNL dedicated simultaneous PET-MRI breast imaging system prototype.