Journal Article

OsteoSense, Animals; Fluorescence; Fluorescent Dyes/*diagnostic use; Guinea Pigs; Lymph Node Excision/*methods; Male; Models, Animal; *Molecular Imaging; Retroperitoneal Space

OBJECTIVES: To propose that fluorescent molecular imaging has utility in specifically identifying the lymph nodes, thereby enabling more definitive lymph node visualization and dissection. Retroperitoneal lymph node dissection (RPLND) is an invasive procedure with significant morbidity. A minimally invasive approach would be of great clinical benefit but has been limited by the extensive perivascular dissection required to remove all lymphatic tissue. Directed lymph node visualization would allow a limited dissection, making a laparoscopic approach more feasible. METHODS: Ten male Hartley guinea pigs underwent nonsurvival RPLND, 5 with the protease activatable in vivo fluorescent molecular imaging agent, ProSense and 5 without image guidance (control). ProSense was administered 24 hours before surgery and detected 24 hours later using a photodynamic detector. In group 1, RPLND was first performed without molecular imaging followed by image-guided lymph node dissection for residual nodes. In group 2, the near infrared detector was used initially for lymph node excision followed by traditionally unassisted extraction of the residual lymph nodes. The lymph nodes were extracted, counted, and sent for histopathologic analysis. RESULTS: With the assistance of molecular imaging, no additional lymph nodes were identified after complete dissection, and all tissue identified by ProSense was confirmed by histopathologic analysis to be lymph nodes. Without molecular imaging, all lymph nodes were not identified, and in 2 instances, the tissue was incorrectly thought to be lymphatic tissue. CONCLUSIONS: Molecular image-guided RPLND is a promising technique to improve in vivo, live visualization and dissection of lymph nodes and has the potential for application in improving the diagnosis and treatment of other urologic malignancies.

Journal Article

Molecular imaging; Abdominal aortic aneurysm; Optical imaging; Pre-clinical; Endovascular imaging; Matrix metalloproteinase; in vivo imaging; MMPSense

Objectives: We present a method to quantify the inflammatory processes that drive abdominal aortic aneurysm (AAA) development that may help predict the rate of growth and thus guide medical and surgical management. We use an in vivo optical molecular imaging approach to quantify protease activity within the walls of AAAs in a rodent model.

Methods: AAAs were generated in mice by topical application of calcium chloride, followed by the administration of the MMP inhibitor doxycycline for 3 months. After this time period, an enzyme-activatable optical molecular imaging agent sensitive to MMP activity was administered, and MMP proteolytic activity was measured in vivo. Histology and in situ zymography were performed for validation. AAAs were also generated in rats, and MMP activity within the walls of the AAAs was also quantified endovascularly.

Results: A dose-dependent response of AAA growth rate to doxycycline administration was demonstrated, with high doses of the drug resulting in nearly complete suppression of aneurysm formation. There was a direct relationship between the rate of aneurysmal growth and measured MMP activity, with a linear best-fit well approximating the relationship. We additionally performed endovascular imaging of AAAs in rats and demonstrated a similar suppression of intramural MMP activity following doxycycline administration.

Conclusions: We present an in vivo evaluation of MMP activity within the walls of AAAs in rodents and show a direct, linear relationship between proteolytic activity and aneurysmal growth. We also illustrate that this functional imaging method can be performed endovascularly, demonstrating potential pre-clinical and clinical applications.

Journal Article

IntegriSense, Animals; Antigens, CD31/metabolism; Capillaries/metabolism; Diagnostic Imaging/*methods; Femoral Artery/surgery; Fluorescent Dyes/*diagnostic use/metabolism; Hindlimb/*blood supply/metabolism/pathology; Integrin alphaV/metabolism; Integrin alphaVbeta3/antagonists & inhibitors/metabolism; Ischemia/*pathology; Ligation; Male; Mice; Mice, Inbred Strains; Microscopy, Fluorescence; *Neovascularization, Physiologic; Plant Lectins/metabolism; Sensitivity and Specificity

Optical agents targeting alpha(v)beta(3) are potential tools to image the angiogenic response to limb ischemia. The left (L) femoral artery was ligated in 17 mice and sham surgery performed on the contralateral right (R) hindlimb. Seven days later, IntegriSense (2 nmol) was injected into 11 mice and 6 were probe controls. Six hours later, mice underwent optical imaging. Ratios of photon flux in the L/R limbs were calculated. Tissue was stained for alpha(v) , CD31, and lectin. The signal was increased in the ischemic limbs compared to contralateral legs and ratio of photon flux in L/R limb averaged 2.37. Control probe showed no hindlimb signal. IntegriSense colocalized with CD31 by dual fluorescent staining. Ratios for L/R hindlimbs correlated with quantitative lectin staining (r = 0.88, p = 0.003). Optical imaging can identify and quantify angiogenic response to hindlimb ischemia.

Journal Article

OsteoSense, Animals; Bone Neoplasms/radionuclide imaging/*secondary; Diagnostic Imaging/*methods; Forecasting; Optics and Photonics/*trends; Positron-Emission Tomography/methods; Tomography, Emission-Computed, Single-Photon/methods; X-Ray Microtomography/methods; X-Rays

Optical Imaging has evolved into one of the standard molecular imaging modalities used in pre-clinical cancer research. Bone research however, strongly depends on other imaging modalities such as SPECT, PET, x-ray and muCT. Each imaging modality has its own specific strengths and weaknesses concerning spatial resolution, sensitivity and the possibility to quantify the signal. An increasing number of bone specific optical imaging models and probes have been developed over the past years. This review gives an overview of optical imaging modalities, models and probes that can be used to study skeletal complications of cancer in small laboratory animals.

Journal Article

Inflammation; Calcification; Atherosclerosis; Molecular imaging; in vivo imaging; ProSense; OsteoSense

Optical molecular imaging represents an emerging method that can detect pathobiological processes in vivo at the cellular and molecular levels, offering a dynamic link between imaging and biology. This review discusses the impact of molecular imaging methods in atherosclerosis research and preventive medicine and focuses on the inflammation-dependent mechanisms of arterial calcification.