SNM 2009 Meeting at Toronto, Canada

I attended the 56^th Annual meeting of Society of Nuclear Medicine (SNM) held from 13^th to 17^th June 2009 at Toronto, Canada. The conference venue was Metro Toronto Convention centre located in the downtown Toronto, just adjacent to Toronto’s Union station.

This was my first time to attend the SNM meeting and was quite awed at the enormity of the meeting organization, attendee’s number and breadth of research covered. The meeting was well organized into various sessions, with each sessions further divided into multiple tracks. Different aspects of research on nuclear medicine and molecular imaging were well covered with multiple sessions running parallel in same time. The number of attendees likely crossed more than 3000.

The first day began with categorical seminars on various topics delivered by experts in the respective fields. I attended few seminars in the morning session of “Critical evaluation of molecular imaging in Neuropsychiatry” where in current advances in schizophrenia imaging and gene effects on psychiatric disorders were discussed. Later I attended the “Molecular Imaging of Hypoxia biology” where in a good background and up-to-date information on tracers for hypoxia imaging in tumors was presented. The discussion following Prof. Fujibayashi’s presentation on Cu-ATSM PET for stem cell imaging was one of the highlight of the session.

The formal opening of the meeting was on next day with a plenary session of Henry N. Wagner Jr Lectureship presented by Dr. John F. Valliant. The presentation gave an overview of multidisciplinary imaging approach using various molecular imaging probes with a focus on breast cancer. The importance of dedicated organ/disease specific cameras such as for imaging breast cancer was mentioned. However, the PET probe mentioned was the FES which is now well established in clinic for breast cancer imaging. Recent interest in multimodal nanoparticle probes was discussed. Examples of SPECT-MRI probes such as ¹¹¹In-MEIO nanoparticles or SPECT-optical such as ⁹⁹Tc-chelate with optical tag or SPECT-ultrasound such as ⁹⁹Tc-chelate with microbubble were mentioned. He also stressed on the application of new chemical labeling strategies which can replace a radiolabeled prosthetic group with a fluorophore such as using single amino acid chelates (SAAC).

The next day’s Cassen lectureship was given by Dr. David Townsend, one of the key inventors of PET/CT scanner. He elaborated on the evolution of today’s PET/CT scanner. It was interesting to note a slide where in he mentioned that one of the first works on PET/CT came from a group in Gunma University in Japan as early as 1984. However, it was not publicized well. The prototype PET/CT machine was developed in 1998 and since then it has evolved rapidly in the PET world market. He also gave a brief overview of current status of PET-MRI machine.

My presentation on “Intratumoral distribution of Cu-ATSM and FDG in lung cancer” was scheduled on the same day in the afternoon session. The presentation was in a session that focused on Lung in Oncology-Clinical diagnosis track. During the discussion period, a question was asked about the absence of Cu-ATSM accumulation in any of the tumors. Although I was lacking sufficient clinical experience to answer that question, I replied that at least in our cohort of patients we did not come across any such case. The questioner further wanted to know if it is possible to make any cut-off value to distinguish the Cu-ATSM accumulation among pathohistologically different patients for which I replied that more patient studies are required.

I also attended many other oral and poster sessions that focused on cancer imaging and development of novel radiopharmaceuticals and had some enlightening discussions during meet-the-author sessions. Overall, the meeting offered me a good insight into the recent research trend in nuclear medicine and molecular imaging. I hope to attend the forthcoming meetings in future.

JSMI 2009 conference at Tokyo, Japan

I attended the 4^th Annual conference of Japanese Society for Molecular Imaging (JSMI) held on 14^th and 15^th May 2009 at Tokyo, Japan. The conference venue was National Science Center located in the heart of Tokyo city, a few minutes walk from Tokyo station.

This was my third time to attend the JSMI meeting. It was quite overwhelming to see increased interest among the medical research fraternity as I could come across people not only working in optical/nuclear medicine based molecular imaging but also physicians from diverse background such as neurology, oncology or cardiology.

The first day began with symposium sessions on Activatable probes and Small animal imaging. The kickoff lecture on Activatable probes was given by Dr. Urano of Tokyo University, who discussed the recent developments of his key pH activatable probe called “TokyoGreens”. Although the topic was familiar to me as he had given a seminar at BIRC in the past, it was worth knowing the recent updates on it. Specifically, the activatable fluorescence of intestinal epithelial cancer cells in vivo probed with TokyoGreens was quite interesting. A lecture from Dr. Tobita of Gunma University on using phosphorescence of Iridium complexes seemed to be an interesting strategy to image hypoxic tumors. The accumulation of Iridium complex called BTP could be visualized for tumor phosphorescence and compared with FDG-PET in various tumor models implanted in mice. Dr. Ozawa from University of Tokyo discussed about imaging protein-protein interactions based on reconstitution of split GFP and split luciferases attached to target proteins following activation by mRNA or drugs that can act on such proteins. In particular, cross complementation using different luciferase domains could be achieved for multispectral evaluation of in vitro studies. In addition, in vivo detection of smads protein interaction and caspase-3 activity were also evaluated. In the Small Animal Imaging session, Dr. Hasegawa lectured about induction of iron-binding ferritin heavy chains in mesothelioma that could be imaged by MRI and its application as a reporter gene for cancer gene therapy. A presentation was made by Dr. Ikawa on imaging of oxidative stress in Parkinson disease patients using ⁶²Cu-ATSM PET. The accumulation of ⁶²Cu-ATSM was well confined to striatum of PD patients, but varied with the progression of the disease.

The keynote lectures were given on the second day by Drs. Dean Sherry and Samuel Achilefu, both from USA. Dr. Sherry talked about the MR sensors of metabolism using lanthanide complexes as CEST and PARACEST agents. It was interesting to note that water exchange in Eu³⁺ based PARACEST systems is extraordinarily sensitive to the chemistry of the side chains. In vivo MRI was performed using different Eu³⁺ derivatives including polymeric PARACEST contrast agents for sensing glucose metabolism or to assess NADH activity. In addition, the potential of utilizing hyperpolarized ¹³C metabolites of lactate and pyruvate were discussed to image specific metabolic processes by MRI in prostate tumors and ischemic heart disease respectively. Dr. Achilefu lectured on utility of optical molecular probes for molecular imaging in tumors. He gave a brief overview of different optical imaging techniques based on flip-flopping contrast mechanisms. In particular, Fluorescent lifetime imaging probes which are pH sensitive and facilitate integrin binding were discussed in detail. Also molecular radionuclear-optical toggle based on a new MOMIA concept to monitor caspase-3 activity was mentioned. It included designing a new NIR fluorphore system that fluoresces differently under the influence of metallic chelates of Cu, Zn and Ni, which are formed as radioactive decay products of ⁶⁴Cu. This synchronization of radionuclide decay and fluorescence enhancements could be utilized for simultaneous evaluation of a biologic activity, in this case of Caspase-3, using PET-OI dual imaging systems. The use of such probes in combination with nanoparticles could push application of optical molecular imaging technologies to human clinical trials in near future.

My poster on intratumoral distribution of Cu-ATSM and FDG was scheduled for presentation on the second day of the meeting.  Some physicians including neurologists as well as PET researchers working on Cu tracers did stop-by and took a keen interest in discussion. Few questions were posed regarding the retention mechanism of the Cu-ATSM and the reasons for differential accumulation pattern in lung cancers.

Few other oral sessions and posters were also interesting but couldn’t comprehend completely due to language barrier. Overall, the 4^th JSMI meeting was a good learning experience and also provided opportunity to reunite with old friends and make new ones.