Ultrasound imaging and contrast agents: A safe alternative to MRI?

Abstract

Microbubble contrast media are used to enhance ultrasound images. Because ultrasound is a real-time investigation, contrast-enhanced ultrasound offers possibilities for perfusion imaging. This review is conducted to evaluate the safety of contrast-enhanced ultrasound and its possible role in medical imaging. The safety of diagnostic ultrasound is still an important field of research. The wanted and unwanted effects of ultrasound and microbubble contrast media as well as the effects of ultrasound on these microbubbles are described. Furthermore, some of the possible applications and indications of contrast-enhanced ultrasound will be discussed. The shared advantages of MRI and ultrasound are the use of non-ionizing radiation and non-nephrotoxic contrast media. From this review it can be concluded that, for certain indications, contrast enhanced ultrasound could be a safe alternative to MRI and a valuable addition to medical imaging.

Multimodality Molecular Imaging of Tumor Angiogenesis

“…2B). Western blotting of the tumor tissue lysate, immunofluorescence staining, and blocking studies with unlabeled VEGF 121 confirmed that the tumor uptake of 64 Cu-DOTA-VEGF 121 was VEGFR specific. That study demonstrated the dynamic nature of VEGFR expression during tumor progression, in that even in the same tumor model, levels of VEGFR expression were dramatically different at different sizes and stages.…”

“…1,4,7,10-Tetraazacyclododecane-N,N9,N$,N$9-tetraacetic acid (DOTA)-VEGF 121 exhibited nanomolar VEGFR-2-binding affinity (comparable to that of VEGF 121 ) in vitro. Small-animal PET imaging revealed rapid, specific, and prominent uptake of 64 Cu-DOTA-VEGF 121 (;15 %ID/g) in highly vascularized small U87MG tumors (high level of VEGFR-2 expression) but significantly lower and sporadic uptake (;3 %ID/g) in large U87MG tumors (low level of VEGFR-2 expression) (Fig. 2B).…”

“…Because of the wider availability of g-cameras and SPECT scanners in the past (30), VEGFR imaging was achieved with SPECT earlier than with PET. Several radioisotopes, such as 123 I, 111 In, 99m Tc, 64 Cu, and 89 Zr, have been used for either SPECT or PET applications.…”

“…We recently labeled VEGF 121 with 64 Cu for PET of VEGFR expression (48). 1,4,7,10-Tetraazacyclododecane-N,N9,N$,N$9-tetraacetic acid (DOTA)-VEGF 121 exhibited nanomolar VEGFR-2-binding affinity (comparable to that of VEGF 121 ) in vitro.…”

“…Before the initiation of treatment, small-animal PET imaging with 64 Cu-VEGF 121 /rGel was performed to evaluate the tumor-targeting efficacy and pharmacokinetics of the fusion protein and thereby determine the dose interval. (This type of study with a radiolabeled drug clearly demonstrates the power of molecular imaging, in that cancer patients can also be selected for molecular cancer therapy on the basis of pretreatment screening with a radiolabeled drug [analog].)…”