Charles Bankhead

Cardiologists impressed by the diagnostic power of PET/CT are beginning to recognize its clinical importance. In sites where the transition from PET to PET/CT has been made, rising cardiac PET imaging volumes have followed.

Molecular imaging will figure prominently in collaborations among public and private interests to modernize the drug development process and make new therapies available more quickly and at lower cost.

PET/CT imaging has evolved in the past five years from an undefined new technology to an invaluable instrument that provides critical information for clinical decision making.

CONTEXT: Proteases play a key role in cancer progression because of their involvement in the degradation of the extracellular matrix and basement membranes. In breast cancer, increased expression of cathepsin-B and other thiol proteases has been associated with increased aggressiveness and poor outcomes. Protease-sensing optical probes have been used in a variety of oncologic imaging applications. Dr. Christoph Bremer and colleagues at Massachusetts General Hospital and the University of Muenster in Germany examined the ability of a cathepsin-sensing fluorescent imaging probe to detect spontaneous breast cancer lesions.

The search for a more sensitive and specific diagnostic test for prostate cancer has led to the burgeoning field of proteomics, providing unprecedented opportunity to identify potential disease biomarkers. With support from the National Cancer Institute's Early Detection Research Network (EDRN), investigators have been examining and comparing protein patterns in the serum of prostate cancer patients and controls. The EDRN initiative makes use of surface-enhanced laser disorption ionization time-of-flight (SELDI-TOF) mass spectrometry.

CONTEXT: Dr. Joanne Kurtzberg, Dr. James M. Provenzale, and colleagues at Duke University prospectively evaluated diffusion-tensor MRI (DTI) anisotropy measurements of white matter regions in Krabbe disease patients treated with stem cell transplantation, a promising new therapeutic approach for a condition that previously had no cure. They compared anisotropy values in infants who underwent stem cell transplantation in the first month of life (before development of clinical signs of Krabbe disease) with those who had the procedure after development of clinical signs of the disease at approximately six months of age.

Although increased total choline (tCho) and phosphocholine (PC) are hallmarks of tumor cells, heterogeneous distribution of tCho is often detected in solid tumors. Kristine Glunde, Ph.D., Zaver Bhujwalla, Ph.D., and their colleagues at Johns Hopkins University Medical Center conducted studies involving combined MR spectroscopy and optical imaging to evaluate tumors derived from human prostate cancer cells stably transfected with green fluorescent protein (GFP) and expressing GFP under hypoxic conditions. The studies routinely revealed coarse colocalization between tCho maps obtained with MRS and hypoxic fluorescing regions detected with optical imaging. Subsequent studies produced evidence suggesting that hypoxia increases tCho, which might contribute to the heterogeneous distribution of tCho observed in vivo.

Cellular MRI is principally performed by labeling cells in culture with an intracellular contrast agent, transplanting the cells into a host, and tracking the migration with MRI. The approach poses potential problems, particularly with respect to stem cells. Cell culture cannot accurately reproduce the chemical and physical niche environment in which stem cells reside. Cell culture might alter the differentiation of stem cells into their natural fate. Eric M. Shapiro, Ph.D., and colleagues at the National Institutes of Health have developed a protocol that avoids the potential problems by means of in vivo labeling of stem cells. Because MRI can detect single-micron-sized particles, poor labeling efficiency does not pose a problem, enabling in vivo stem cell labeling and tracking.

Solving the mysteries of the hostile microenvironment of tumors serves as a research focal point in the laboratory of Robert Gillies, Ph.D., a professor of biochemistry and molecular physics and radiology at the University of Arizona.

Frustrated by the limitations of basic imaging research, Dr. Christopher Contag has literally found a solution glowing in the dark.