Tag Archives: nuclear imaging

Medicine Wellness Health

Prostate cancer: Identifying and destroying the tumour through nuclear medicine therapy

(Vienna, December 13, 2016) Prostate cancer patients who are resistant to hormone treatment used to have a poor prognosis. Until recently, the diagnostic and therapeutic possibilities had been limited, but now innovative developments in nuclear medicine imaging and therapy open up promising pathways. Novel substances used with PET/CT (positron-emission tomography combined with computed tomography) not only allow for better diagnosis but also offer treatment options where other therapies have failed. „This offers a glimpse of hope to patients who suffer from this particularly severe form of prostate cancer,“ says EANM expert Prof. Markus Luster.
Prostate cancer is the second most frequently diagnosed cancer in men and causes around 90.000 deaths per year in Europe. Up to every second patient who has his prostate surgically removed or has undergone radiation therapy suffers from relapse. In severe cases the level of testosterone upon which the tumour is dependent to a large extent has to be reduced drastically in order to fight the disease. This is usually done by hormone therapy. However, a considerable number of patients are or will become resistant to this kind of treatment (so called castration-resistant prostate cancer / CRPC). This means that in spite of therapy the tumour has not been destroyed definitively and in many cases is now affecting the lymph nodes or has even extended to the stage of often painful bone metastases. Prognosis of patients who progress to this stage is poor.

A common means to detect prostate cancer and assess the stage of the disease is the measurement of the level of prostate-specific antigen (PSA), which serves as a biomarker for the presence of cancer cells. However, in patients whose testosterone production has been suppressed medically PSA levels are often too low to be measured. This includes CRPC patients in whom this therapy has failed to eradicate or halt the tumour. Moreover, PSA measurement provides no information about the sites and the extent of the recurrent cancer. However, newly developed nuclear medicine methods have opened up promising diagnostic avenues that might more sensitively and accurately enlighten both patient and physician about the location and extent of disease. At the same time, this new approach also provides new therapeutic modalities which can improve the still poor prognosis of CRPC-patients in the future. The leading part is played by a protein called Prostate-Specific Membrane Antigen (PSMA). It is found abundantly on the surface of prostate cancer cells and its number appears to be increasing with the aggressiveness of the disease. This makes PSMA an ideal target for detecting cancer cells by nuclear imaging. The essential means to achieve this is the Ga-68-PSMA-ligand, a substrate that binds to PSMA – comparable to a key that fits into its lock – which is labelled with the radionuclide Gallium 68. This tracer has already been used successfully in a large number of PET/CT examinations: After the patient has been injected with Ga-68-PSMA-ligand the tracer is taken up by the cancer cells which are made visible for the examining physicians by the radiation. „The substance has proven to be highly sensitive and reliable in detecting carcinoma in lymph nodes as well as metastases in other body regions. Over the past decade or so other substances such as choline have been evaluated and applied but in terms of accuracy and diagnostic outcome Ga-68-PSMA is now state of the art,“ says Prof. Markus Luster.

As he points out PSMA is not only useful for diagnostic but also for treatment purposes: The PSMA-ligand can be labelled with another radionuclide called Lutetium-177 that is able to destroy the cancer cell from inside through radiation. „Several tests have demonstrated that Lu-177-PSMA-therapy can reduce tumour mass and alleviate pain. Patients who have no other treatment options left and whose cancer cells have been shown to take up PSMA-ligands are very likely to benefit from the diagnostic and therapeutic potential of PSMA imaging and therapy,“ says Prof. Markus Luster.
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Presseagentur für Medizinthemen

Kontakt
impressum health & science communication
Frank von Spee
Hohe Brücke 1
20459 Hamburg
040 31786410
vonspee@impressum.de
http://www.impressum.de

Medicine Wellness Health

Myocardial nuclear imaging: Minimizing the dose – preserving the diagnostic value

(Vienna, September 6, 2016) Cardiac scintigraphy plays an important role in the evaluation of patients with a suspicion or known coronary artery disease (angina pectoris, myocardial infarction), but submitted patients to higher levels of radiations in comparison to other imaging techniques. New detection systems (CZT cameras) have become available that offer to reduce dramatically the level of radiations associated to cardiac scintigraphy. „Using these new systems, we can provide cardiologists with critical information on the status of the vessels supplying blood within the heart and expose patients to only minimal levels of radiations ,“ says Dr.FabienHyafil, expert of the European Association of Nuclear Medicine (EANM).

Cardiovascular diseases (CVD) remain the first cause of death in Europe with five million casualties every year. When the arteries supplying blood to the heart muscle (coronary arteries) are narrowed or occluded, blood flow is impaired in the downstream cardiac regions of the heart causing angina pectoris or myocardial infarction. Cardiac scintigraphy is an imaging technique that allows for the assessment of the blood flow within the heart muscle during exercise and at rest. This procedure requires the injection of a small amount of a radiopharmaceutical in a vein that is then taken up by the cardiac muscle proportional to local blood flow. Hence, cardiac scintigraphy allows for the localization of areas in the heart with an insufficient blood supply. This information helps to identify patients at higher risk of presenting a myocardial infarction and who benefit the most from interventional procedures that restore normal blood flow to the heart (percutaneous coronary angioplasty or coronary by-pass interventions). Cardiac scintigraphy is a robust and accurate imaging technique for the evaluation of patients with coronary artery disease but exposes patients to higher level of radiations than other imaging techniques.
Decreasing radiation exposure of patients from medical imaging
Medical imaging techniques such as computed tomography (CT) or scintigraphy are based on the detection of X-rays passing through the body or gamma-rays emitted by radiopharmaceuticals accumulating in organs. These imaging techniques enable precise characterization of the heart anatomy and function but expose patients to radiations. Repeated exposure to radiations may damage living tissue by changing cell structure and altering DNA. The level of radiations associated with medical imaging is low and no significant increase in the risk of cancer in relation to medical imaging has been identified so far. Nevertheless, there is a raising concern that the levels of radiations received by patients throughout lifetime is growing, in particular as a consequence of repeated medical imaging procedures. In this context, efforts have been directed towards reducing the level of radiations associated with medical imaging.

Lower radiopharmaceutical doses – preserved high diagnostic performances
New detection systems called „CZT cameras“ have recently become available for cardiac scintigraphy and are installed in an increasing number of nuclear medicine departments across Europe. In the detectors used for these cameras, the conventional cumbersome sodium-iodide crystals used for the detection of gamma rays have been replaced by cadmium-zinc-telluride (CZT) semi-conductor crystals, that are much thinner and more flexible. New cameras dedicated to cardiac imaging have been designed taking advantage of the favorable properties of CZT-based detectors that offer a larger surface for signal detection and focused on the heart region. The efficacy of these CZT cameras for signal detection is improved by 4- to 7-fold in comparison to conventional systems and, hence, enables to decrease significantly the dose of radiopharmaceutical injected to patients for cardiac scintigraphy and their exposure to radiations. A French team1 recently demonstrated that patient exposure to radiations in relation to cardiac scintigraphy can be divided by 3 using CZT cameras. „CZT cameras represent an important breakthrough for the reduction of radiation exposure induced by medical imaging. Using these new systems, patients are now exposed to only very low levels of radiations for cardiac scintigraphy with a preserved high diagnostic yield of the test,“ says Dr.FabienHyafil.

Presseagentur für Medizinthemen

Kontakt
impressum health & science communication
Frank von Spee
Hohe Brücke 1
20459 Hamburg
040 31786410
vonspee@impressum.de
http://www.impressum.de