Characterization of normal and cancerous lymph nodes on indirect computed tomography lymphographic studies after interstitial injection of iodinated nanoparticles

Theranostic nanomedicine for cancer detection and treatment

Cancer is the second leading cause of death in the USA according to the American Cancer Society. In the past 5 years, “theranostic nanomedicine”, for both therapeutics and imaging, has shown to be “the right drug for the right patient at the right moment” to manage deadly cancers. This review article presents an overview of recent developments, mainly from the authors’ laboratories, along with potential medical applications for theranostic nanomedicine including basic concepts and critical properties. Finally, we outline the future research direction and possible challenges for theranostic nanomedicine research.

Imaging efficiency of an X-ray contrast agent-incorporated polymeric microparticle

Biocompatible polymeric encapsulants have been widely used as a delivery vehicle for a variety of drugs and imaging agents. In this study, X-ray contrast agent (iopamidol) is encapsulated into a polymeric microparticle (polyvinyl alcohol) as a particulate flow tracer in synchrotron X-ray imaging system. The physical properties of the designed microparticles are investigated and correlated with enhancement in the imaging efficiency by experimental observation and theoretical interpretation. The X-ray absorption ability of the designed microparticle is assessed by Beer-Lambert-Bouguer law. Particle size, either in dried state or in solvent, primarily dominates the X-ray absorption ability under the given condition, thus affecting imaging efficiency of the designed X-ray contrast flow tracers.

Emerging implications of nanotechnology on cancer diagnostics and therapeutics

Nanotechnology is multidisciplinary field that involves the design and engineering of objects <500 nanometers (nm) in size. The National Cancer Institute has recognized that nanotechnology offers an extraordinary, paradigm-changing opportunity to make significant advances in cancer diagnosis and treatment. In the last several decades, nanotechnology has been studied and developed primarily for use in novel drug-delivery systems (e.g. liposomes, gelatin nanoparticles, micelles). A recent explosion in engineering and technology has led to 1) the development of many new nanoscale platforms, including quantum dots, nanoshells, gold nanoparticles, paramagnetic nanoparticles, and carbon nanotubes, and 2) improvements in traditional, lipid-based nanoscale platforms. The emerging implications of these platforms for advances in cancer diagnostics and therapeutics form the basis of this review. A widespread understanding of these new technologies is important, because they currently are being integrated into the clinical practice of oncology.

Breast Sentinel Lymph Node Navigation With Three-Dimensional Interstitial Multidetector-Row Computed Tomographic Lymphography

OBJECTIVE

Three-dimensional multidetector-row computed tomographic lymphography (3D MDCT-LG) with interstitial injection of a widely available nonionic monometric contrast medium iopamidol was used for navigation of breast sentinel lymph node (SLN) biopsy.

METHODS

3D MDCT-LG was obtained after massage of the interstitially injection sites of a total of 4-5 mL undiluted iopamidol at periareolar and peritumoral areas in 68 consecutive patients with early-stage breast cancer, using a 4 detector-row CT scanner. Drainage lymphatic patterns and SLN anatomy were assessed on 3D MDCT-LG images. 3D MDCT-LG-navigated SLN biopsy with combined use of blue dye was followed by backup axillary lymph node dissection to evaluate accuracy of SLN biopsy.

RESULTS

The 3D MDCT-LG images clearly localized primary SLNs by visualizing the direct connection between these nodes and their afferent lymphatic vessels on detailed anatomy of the surrounding structures in all patients. Drainage lymphatic pathways on these images were classified into 4 patterns: single route/single SLN (39 cases, 57%), multiple routes/multiple SLNs (10 cases, 15%), single route/multiple SLNs (9 cases, 13%), and multiple routes/single SLN (10 cases, 15%). Under 3D MDCT-LG navigation, SLNs was found at the accurate location in all patients. With backup axillary lymph node dissection, metastasis was found in 14 (20%) patients, and 8 of these patients had metastasis only in the preoperatively identified SLNs. In other 5 positive patients, metastasis was found both in the SLN and non-SLNs. However, micrometastasis eventually was found only in non-SLN in an elderly patient. Overall, the sensitivity, false-negative rate, and accuracy of 3D CT-L-navigated SLN biopsy were 92% (13/14 patients), 7% (1/14 patients), and 98% (67/68 patients), respectively.

CONCLUSIONS

Topographic 3D interstitial MDCT-LG can be a widely available and reliable navigator for breast SLN biopsy.

Breast sentinel lymph node mapping at CT lymphography with iopamidol: preliminary experience

PURPOSE

To evaluate sentinel lymph node (SLN) mapping with interstitial computed tomographic (CT) lymphography with small volumes of iopamidol for direction of SLN biopsy in breast cancer.

MATERIALS AND METHODS

Thin-section transverse and three-dimensional CT images that included the breast and axilla were acquired at multi-detector row helical CT in 17 patients with operable breast cancer before subcutaneous injection of 2 mL of undiluted iopamidol into peritumoral and periareolar areas and 1-5 minutes after massage of injection sites. Location and size of SLNs were assessed at CT lymphography and were compared with SLNs at standard axillary lymph node dissection with blue dye staining.

RESULTS

CT lymphography allowed localization of SLNs in all patients by means of visualization of a direct connection between an SLN and its afferent lymphatic vessels draining from the injection sites. Afferent vessels were joined and drained into a single axillary SLN, except in four patients with two or three SLNs, including a parasternal one. SLNs did not enhance because of rerouting of lymph flow in four patients. At surgery, SLNs that were stained or not stained with blue dye were easily found with CT lymphographic guidance. Tumoral infiltration was not evident in any resected nodes, except for infiltration in one patient with micrometastasis in SLN alone and infiltration in four patients with massive metastasis in both SLN and distant nodes.

CONCLUSION

Because preoperative CT lymphography-guided SLN mapping provides SLN position with detailed lymphatic anatomy, it may be useful for the direction of breast SLN biopsy.

Interstitial CT lymphography-guided localization of breast sentinel lymph node: preliminary results

BACKGROUND

Accurate localization of the breast sentinel lymph node (SLN) can be challenging as a minimally invasive approach to the treatment of early-stage breast cancer. We tested the potential capability of interstitial computed tomographic lymphography (CT-LG) using a conventional contrast agent (iopamidol) for SLN mapping.

METHODS

In 14 female dogs, 0.5 and 1 mL of undiluted iopamidol was injected subcutaneously into the 2 skin areas overlying the mammary gland. Contiguous, 2 mm-thick multidetector helical CT images were obtained through the upper breast and axilla before, and for 60 minutes after, gentle massage at the injection site. Three-dimensional (3D) CT images were obtained from the postcontrast images showing the greatest SLN enhancement. This CT-LG with 2 mL of iopamidol was also evaluated in 5 human female volunteers.

RESULTS

The direct connection of SLN and lymphatic vessels draining from the injection sites in the animal models was clearly visualized, even with 0.5 mL of iopamidol. With this dose, the SLN attenuation was maximally enhanced, with a mean of 274 Hounsfield units (HU) on the first postcontrast images. The topographic 3D images provided the comprehensive anatomy of these lymphatic pathways. Of the 28 SLNs and 184 distant nodes visualized on CT images, all of the SLNs (100%) and 161 (87.5%) of the distant nodes could be resected at premortem and/or postmortem, with a good correlation in the locations and sizes with those on the CT images. The CT-LG effectively localized 5 SLNs with averaged maximum attenuation of 223 HU in the human volunteers, without any significant adverse effects.

CONCLUSION

Interstitial CT-LG using small volumes of iopamidol can sufficiently visualize breast lymphatic drainage and may have potential utility for breast SLN mapping.

Visualization of breast lymphatic pathways with an indirect computed tomography lymphography using a nonionic monometric contrast medium iopamidol: preliminary results

RATIONALE AND OBJECTIVES

The capability of an indirect computed tomographic lymphography (CT-LG) using a nonionic monometric contrast medium iopamidol for visualizing breast lymphatic pathways was preliminarily tested.

MATERIALS AND METHODS

In 10 female dogs, a total of 0.5 and 1 mL of undiluted iopamidol was injected subcutaneously into the skin areas overlying the both caudal mammary glands. Contiguous 2-mm-thick multidetector raw helical CT images were obtained through the upper thorax and axilla before and during 60 minutes after gentle massage at the injection sites, with reconstruction into three-dimensional (3D) postcontrast CT images. The first lymph node (1st LN) directly draining from the injection sites was marked under CT guidance, followed by pre- and postmortem examinations. This CT-LG with 2-mL iopamidol was also attempted in five human female volunteers.

RESULTS

Even with 0.5-mL iopamidol, the CT-LG clearly visualized the direct connection of the 1st LN and lymphatic vessels draining from the injection sites throughout the examination time in all the animals, with the maximum CT attenuation of 269 Hounsfield units (HU) +/- 137 in the 1st LN on the first postcontrast images. The topographic 3D images provided comprehensive anatomic outlines of these lymphatic pathways. Of the total of 20 opacified 1st LN and 110 distant nodes, all the 1st LN (100%) and 92 (83.6%) distant nodes could be resected at pre- or postmortem, with a good correlation with the CT images. The CT-LG also effectively localized the 1st LN with the maximum attenuation of 223 HU +/- 63 in the human volunteers, without any significant late adverse effects.

CONCLUSION

Indirect CT-LG with iopamidol may have excellent potential for visualizing breast lymphatic drainage and for preoperative localization of breast sentinel lymph nodes.

Nanoparticles in cancer therapy and diagnosis

Numerous investigations have shown that both tissue and cell distribution profiles of anticancer drugs can be controlled by their entrapment in submicronic colloidal systems (nanoparticles). The rationale behind this approach is to increase antitumor efficacy, while reducing systemic side-effects. This review provides an update of tumor targeting with conventional or long-circulating nanoparticles. The in vivo fate of these systems, after intravascular or tumoral administration, is discussed, as well as the mechanism involved in tumor regression. Nanoparticles are also of benefit for the selective delivery of oligonucleotides to tumor cells. Moreover, certain types of nanoparticles showed some interesting capacity to reverse MDR resistance, which is a major problem in chemotherapy. The first experiments, aiming to decorate nanoparticles with molecular ligand for 'active' targeting of cancerous cells, are also discussed here. The last part of this review focus on the application of nanoparticles in imaging for cancer diagnosis.

A surface-modified chylomicron remnant-like emulsion for percutaneous computed tomography lymphography: synthesis and preliminary imaging findings

RATIONALE AND OBJECTIVES

To assess a surface-modified emulsion as a percutaneous CT lymphographic agent in normal dogs.

METHODS

An iodinated chylomicron remnant-like microemulsion was formulated with a mean particle size of 91.3 nm and an iodine concentration of 91 mg I/mL. Contrast material (2 mL) was injected into the subcutaneous tissues of the metatarsus and metacarpus of six normal dogs to enhance popliteal and cervical lymph nodes, respectively. CT images were acquired at 0, 15, 30, 45, 60, 240, 480, and 1440 minutes.

RESULTS

Significant lymph node enhancement occurred in as little as 15 minutes after injection and persisted at least 8 hours. Node opacification was most pronounced at 1 to 4 hours postinjection and exceeded 200 HU in some nodes (precontrast attenuation = 45 HU). Marked enhancement of popliteal efferent lymphatics and of iliac and sacral node groups also occurred indicating distribution to second order nodes. Attenuation of enhanced nodes reverted to precontrast levels by 24 hours.

CONCLUSION

The new surface-modified, chylomicron remnant-like emulsion provided marked, selective enhancement of targeted lymph nodes after subcutaneous administration. Moreover, the formulation produced significant opacification of more distant node groups from a single injection.

Long-term effect of irradiation on lymph node uptake of interstitially delivered nanoparticulate contrast media

RATIONALE AND OBJECTIVES

To characterize the long-term effects of therapeutic doses of ionizing radiation on the uptake and distribution of percutaneously delivered particulate contrast media in normal lymph nodes.

METHODS

Two milliliters of an iodinated nanoparticle suspension (76 mg I/mL) was injected subcutaneously or submucosally into nine normal adult beagles. Region of interest analysis was used to estimate the volume, attenuation, and iodine concentration of opacified targeted lymph nodes and nonopacifled contralateral nodes on 24-hour postinjection CT images. All lymph nodes were then irradiated with 50 Gy in 25 fractions of 2 Gy/d. Contrast-enhanced quantitative CT was repeated 12 months after irradiation.

RESULTS

Contrast-enhanced nodes averaged 2.3+/-0.8 times the volume of nonenhanced contralateral nodes before irradiation. The mean attenuation of contrast-enhanced nodes increased to 305 to 380 Hounsfield units from a pre-enhancement value of approximately 25 Hounsfield units. Opacified node volumes after irradiation averaged 61% to 86% of preirradiation volumes but were generally not statistically different. Contrast uptake assessed by average attenuation and iodine concentration decreased significantly by an average of 17% to 22% after irradiation and was significantly less than preirradiation uptake. Qualitatively, irradiated nodes generally appeared smaller than nonirradiated nodes, but the distribution pattern of contrast media did not appear to be appreciably altered.

CONCLUSIONS

Lymph node irradiation resulted in only minimal decreases in contrast media uptake and node volume at 12 months. These effects presumably would not appreciably alter the potential clinical value of indirect lymphography for evaluating patients undergoing radiation therapy.

Time course of nodal enhancement with CT X-ray nanoparticle contrast agents: effect of particle size and chemical structure

RATIONALE AND OBJECTIVES

Levels of CT enhancement in rabbit lymph nodes were followed with time after subcutaneous injection of four iodinated, insoluble nanoparticle contrast agents to provide experimental support for the hypothesis that clearance of these agents is related to the chemical structure of the agent itself. The impact of particle size was also studied.

METHODS

Subcutaneous injections (2 x 0.25 mL) were made in the dorsum of rabbit paws with 15% suspensions of four nanoparticle contrast agents. Images were obtained at 4, 10, 24, 48, and 72 hours and 5, 7, and 14 days after injection. Average attenuation (in Hounsfield units [HU]), node volume, and total iodine uptake were estimated from the CT scans for each lymph node at each time point.

RESULTS

All the agents provided adequate enhancement of both the popliteal and axillary lymph nodes of the rabbit (ie, > delta100 HU). Lymph node volume appears to be related to the persistence of enhancement, with long-lived agents demonstrating the greatest increase in size. The rate of clearance from the lymph nodes is related to the structure of the agent.

CONCLUSIONS

Clearance of insoluble, iodinated nanoparticle contrast agents from lymph nodes can be modulated by changes in the structure of the agent itself. Using the same agent, smaller particles deliver material to the lymph nodes more quickly and clear more quickly.

Lymph node extraction of radiopaque nanoparticulates in the rabbit as measured in vivo with CT

RATIONALE AND OBJECTIVES

The purpose of this study was to estimate in vivo extraction of lymphographic material in the popliteal node of the rabbit.

MATERIALS AND METHODS

Serial quantitative computed tomography (CT) of target tissues in four legs of two rabbits was performed after subcutaneous injection of an improved lymphographic contrast agent. Massage was used as a lymphotrophic intervention.

RESULTS

At 15 minutes, the mean change in Hounsfield units measured 815 in the popliteal node, 219 in afferent lymphatic vessels, and 127 in efferent lymphatic vessels. The nodal extraction of nanoparticulates from the lymph was approximately 55%. Nodal massage allowed the amount of nanoparticulate remaining in sinusoidal lymph to be estimated.

CONCLUSION

Functional CT performed with timed studies, proper radiopaque materials, and physiologic interventions can depict in vivo lymphatic physiology under minimally invasive conditions.