Noninvasive Nodal Staging in Patients With Breast Cancer Using Gadofosveset-Enhanced Magnetic Resonance Imaging: A Feasibility Study

A non-invasive artificial intelligence model for identifying axillary pathological complete response to neoadjuvant chemotherapy in breast cancer: a secondary analysis to multicenter clinical trial

BACKGROUND

This study aims to develop a stacking model for accurately predicting axillary lymph node (ALN) response to neoadjuvant chemotherapy (NAC) using longitudinal MRI in breast cancer.

METHODS

We included patients with node-positive breast cancer who received NAC following surgery from January 2012 to June 2022. We collected MRIs before and after NAC, and extracted radiomics features from the tumour, peritumour, and ALN regions. The Mann-Whitney U test, least absolute shrinkage and selection operator, and Boruta algorithm were used to select features. We utilised machine learning techniques to develop three single-modality models and a stacking model for predicting ALN response to NAC.

RESULTS

This study consisted of a training cohort (n = 277), three external validation cohorts (n = 313, 164, and 318), and a prospective cohort (n = 81). Among the 1153 patients, 60.62% achieved ypN0. The stacking model achieved excellent AUCs of 0.926, 0.874, and 0.862 in the training, external validation, and prospective cohort, respectively. It also showed lower false-negative rates (FNRs) compared to radiologists, with rates of 14.40%, 20.85%, and 18.18% (radiologists: 40.80%, 50.49%, and 63.64%) in three cohorts. Additionally, there was a significant difference in disease-free survival between high-risk and low-risk groups (p < 0.05).

CONCLUSIONS

The stacking model can accurately predict ALN status after NAC in breast cancer, showing a lower false-negative rate than radiologists.

TRIAL REGISTRATION NUMBER

The clinical trial numbers were NCT03154749 and NCT04858529.

Axillary lymph node response to neoadjuvant systemic therapy with dedicated axillary hybrid 18F-FDG PET/MRI in clinically node-positive breast cancer patients: a pilot study

AIM

To investigate the diagnostic performance of dedicated axillary hybrid ¹⁸F-2-[¹⁸F]-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET)/magnetic resonance imaging (MRI) in detecting axillary pathological complete response (pCR) following neoadjuvant systemic therapy (NST) in clinically node-positive breast cancer patients.

MATERIALS AND METHODS

Ten prospectively included clinically node-positive breast cancer patients underwent dedicated axillary hybrid ¹⁸F-FDG PET/MRI after completing NST followed by axillary surgery. PET images were reviewed by a nuclear medicine physician and coronal T1-weighted and T2-weighted MRI images by a radiologist. All axillary lymph nodes visible on PET/MRI were matched with those removed during axillary surgery. Diagnostic performance parameters were calculated based on patient-by-patient and node-by-node validation with histopathology of the axillary surgical specimen as the reference standard.

RESULTS

Six patients achieved axillary pCR at final histopathology. A total of 84 surgically harvested axillary lymph nodes were matched with axillary lymph nodes depicted on PET/MRI. Histopathological examination of the matched axillary lymph nodes resulted in 10 lymph nodes with residual axillary disease of which eight contained macrometastases and two micrometastases. The patient-by-patient analysis yielded a sensitivity, specificity, positive predictive value, and negative predictive value of 25%, 100%, 100%, and 67%, respectively. The diagnostic performance parameters of the node-by-node analysis were 0%, 96%, 0%, and 88%, respectively. Excluding micrometastases from the node-by-node analysis increased the negative predictive value to 90%.

CONCLUSION

This pilot study suggests that the negative predictive value and sensitivity of dedicated axillary ¹⁸F-FDG PET/MRI are insufficiently accurate to detect axillary pCR or exclude residual axillary disease following NST in clinically node-positive breast cancer patients.

Added Value of MRI for Invasive Breast Cancer including the Entire Axilla for Evaluation of High-Level or Advanced Axillary Lymph Node Metastasis in the Post-ACOSOG Z0011 Trial Era

Background In the post-American College of Surgeons Oncology Group Z0011 trial era, radiologists have increasingly focused on excluding high-level or advanced axillary lymph node metastasis (ALNM) by using an additional MRI scan positioned higher than lower axillae; however, the value of these additional scans remains undetermined. Purpose To evaluate whether a standard MRI protocol is sufficient to exclude high-level or advanced ALNM in breast cancer or additional MRI of entire axilla is needed. Materials and Methods This retrospective study evaluated women with invasive breast cancer who underwent breast MRI from April 2015 to December 2016. Some underwent neoadjuvant chemotherapy (NAC) and others underwent upfront surgery. Standard (routine axial scans including the lower axillae) and combined (routine axial scans plus additional scans including the entire axilla) MRI protocols were compared for high-level or advanced ALNM detection. Clinical-pathologic characteristics were analyzed. Uni- and multivariable logistic regression was performed to identify predictors of high-level or advanced ALNM. Results A total of 435 women (mean age ± standard deviation, 52 years ± 11) were evaluated (65 in the NAC group, 370 in the non-NAC group). With the standard MRI protocol, predictors of high-level ALNM were peritumoral edema (odds ratio [OR], 12.3; 95% CI: 3.9, 39.4; P < .001) and positive axilla (OR, 5.9; 95% CI: 2.0, 15.2; P < .001). Only three of 289 women with negative axillae without peritumoral edema had high-level ALNM. Predictors of advanced ALNM were positive axillae (OR, 8.9; 95% CI: 3.7, 21.5; P < .001) and peritumoral edema (OR, 2.8; 95% CI: 1.1, 6.9; P = .03). Only six of 310 women who had negative axillae without peritumoral edema had advanced ALNM. Conclusion The performance of standard MRI was satisfactory in excluding high-level and advanced axillary lymph node metastasis in most patients with breast cancer. However, the presence of peritumoral edema or positive axillae in the MRI findings emphasizes the benefits of a combined MRI protocol. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Abe in this issue.

Dedicated Axillary MRI-Based Radiomics Analysis for the Prediction of Axillary Lymph Node Metastasis in Breast Cancer

Radiomics features may contribute to increased diagnostic performance of MRI in the prediction of axillary lymph node metastasis. The objective of the study was to predict preoperative axillary lymph node metastasis in breast cancer using clinical models and radiomics models based on T2-weighted (T2W) dedicated axillary MRI features with node-by-node analysis. From August 2012 until October 2014, all women who had undergone dedicated axillary 3.0T T2W MRI, followed by axillary surgery, were retrospectively identified, and available clinical data were collected. All axillary lymph nodes were manually delineated on the T2W MR images, and quantitative radiomics features were extracted from the delineated regions. Data were partitioned patient-wise to train 100 models using different splits for the training and validation cohorts to account for multiple lymph nodes per patient and class imbalance. Features were selected in the training cohorts using recursive feature elimination with repeated 5-fold cross-validation, followed by the development of random forest models. The performance of the models was assessed using the area under the curve (AUC). A total of 75 women (median age, 61 years; interquartile range, 51-68 years) with 511 axillary lymph nodes were included. On final pathology, 36 (7%) of the lymph nodes had metastasis. A total of 105 original radiomics features were extracted from the T2W MR images. Each cohort split resulted in a different number of lymph nodes in the training cohorts and a different set of selected features. Performance of the 100 clinical and radiomics models showed a wide range of AUC values between 0.41-0.74 and 0.48-0.89 in the training cohorts, respectively, and between 0.30-0.98 and 0.37-0.99 in the validation cohorts, respectively. With these results, it was not possible to obtain a final prediction model. Clinical characteristics and dedicated axillary MRI-based radiomics with node-by-node analysis did not contribute to the prediction of axillary lymph node metastasis in breast cancer based on data where variations in acquisition and reconstruction parameters were not addressed.

Diagnostic performance of standard breast MR imaging compared to dedicated axillary MR imaging in the evaluation of axillary lymph node

BACKGROUND

Breast magnetic resonance (MR) imaging does not usually assess axillary lymph nodes -using dedicated axillary sequence. The additional utility of dedicated axillary sequence is poorly understood. We evaluated the diagnostic performance of dedicated axillary imaging sequence for evaluation of axillary lymph node.

METHODS

In this retrospective study from January 2018 to March 2018, 750 consecutive women underwent breast MR imaging. 263 patients were excluded, due to neoadjuvant chemotherapy (n = 235), incomplete histopathological information (n = 14) and follow-up loss (n = 14), 487 women were included. Two radiologists scored lymph node on confidence level scale from 0 (definitely benign) to 4 (definitely malignant), -using standard MR and dedicated axillary imaging sequences. Diagnostic performance parameters were compared and calculated correlation coefficient of quantitative features (largest dimension, cortical thickness, and the ratio of cortical thickness to largest dimension of lymph node).

RESULTS

68 (14.0%) were node-positive and 419 (86.0%) were node-negative. The sensitivity, specificity, positive, negative predictive values and accuracy were respectively, 66.2, 93.3, 61.6, 94.4, and 89.5% for dedicated axillary sequence and 64.7, 94.0, 63.8, 94.3, 89.9% for standard MR sequence The dedicated axillary and standard sequences s did not exhibit significant differences in detection of positive lymph nodes (AUC, 0.794 for standard and 0.798 for dedicated axillary sequence, P = 0.825). The cortical thickness appeared to be the most discriminative quantitative measurement using both axillary (AUC, 0.846) and standard sequences (AUC, 0.823), with high correlation coefficient (0.947).

CONCLUSION

Evaluation of axillary nodal status using standard breast MR imaging is comparable to dedicated axillary MR imaging.

Heterogeneous Enhancement Pattern in DCE-MRI Reveals the Morphology of Normal Lymph Nodes: An Experimental Study

Purpose

To investigate the heterogeneous enhancement pattern in normal lymph nodes of healthy mice by different albumin-binding contrast agents.

Methods

The enhancement of normal lymph nodes was assessed in mice by dynamic contrast-enhanced MRI (DCE-MRI) after the administration of two contrast agents characterized by different albumin-binding properties: gadopentetate dimeglumine (Gd-DTPA) and gadobenate dimeglumine (Gd-BOPTA). To take into account potential heterogeneities of the contrast uptake in the lymph nodes, k-means cluster analysis was performed on DCE-MRI data. Cluster spatial distribution was visually assessed. Statistical comparison among clusters and contrast agents was performed on semiquantitative parameters (AUC, wash-in rate, and wash-out rate) and on the relative size of the segmented clusters.

Results

Cluster analysis of DCE-MRI data revealed at least two main clusters, localized in the outer portion and in the inner portion of each lymph node. With both contrast agents, AUC (p < 0.01) and wash-in (p < 0.05) rates were greater in the inner cluster, which also showed a steeper wash-out rate than the outer cluster (Gd-BOPTA, p < 0.01; Gd-DTPA, p=0.056). The size of the outer cluster was greater than that of the inner cluster by Gd-DTPA (p < 0.05) and Gd-BOPTA (p < 0.01). The enhancement pattern of Gd-DTPA was not significantly different from the enhancement pattern of Gd-BOPTA.

Conclusion

DCE-MRI in normal lymph nodes shows a characteristic heterogeneous pattern, discriminating the periphery and the central portion of the lymph nodes. Such a pattern deserves to be investigated as a diagnostic marker for lymph node staging.

The Changing World of Breast Cancer: A Radiologist's Perspective

Compared with other fields of medicine, there is hardly an area that has seen such fast development as the world of breast cancer. Indeed, the way we treat breast cancer has changed fundamentally over the past decades. Breast imaging has always been an integral part of this change, and it undergoes constant adjustment to new ways of thinking. This relates not only to the technical tools we use for diagnosing breast cancer but also to the way diagnostic information is used to guide treatment. There is a constant change of concepts for and attitudes toward breast cancer, and a constant flux of new ideas, new treatment approaches, and new insights into the molecular and biological behavior of this disease. Clinical breast radiologists and even more so, clinician scientists, interested in breast imaging need to keep abreast with this rapidly changing world. Diagnostic or treatment approaches that are considered useful today may be abandoned tomorrow. Approaches that seem irrelevant or far too extravagant today may prove clinically useful and adequate next year. Radiologists must constantly question what they do, and align their clinical aims and research objectives with the changing needs of contemporary breast oncology. Moreover, knowledge about the past helps better understand present debates and controversies. Accordingly, in this article, we provide an overview on the evolution of breast imaging and breast cancer treatment, describe current areas of research, and offer an outlook regarding the years to come.

Is sentinel lymph node biopsy a viable alternative to complete axillary dissection following neoadjuvant chemotherapy in women with node-positive breast cancer at diagnosis? An updated meta-analysis involving 3,398 patients

BACKGROUND

The use of sentinel lymph node biopsy (SLNB) following neoadjuvant chemotherapy (NAC) in patients presenting with clinically positive lymph nodes remains controversial.

METHODS

A computer-aided search of the literature regarding SLNB in clinically node-positive breast cancer treated with NAC was carried out to identify the false negative rate (FNR), sentinel lymph node identification rate (IR), and axillary pathological complete response (pCR).

RESULTS

Nineteen articles were used in the analysis yielding 3,398 patients. The pooled estimate of the FNR was 13% and that of the IR was 91%. The adjusted pCR rate was 47%. A trend toward significance was observed with only clinical stage N1 (cN1) disease whereby clinical stage N1 was associated with an increased pCR rate when compared to N2 or N3 disease (P = .06).

CONCLUSIONS

SLNB after NAC in biopsy-proven node-positive patients results in reasonably acceptable FNR and IR, making it a valid alternative management strategy to axillary dissection. More refined patient selection and optimal techniques can improve the FNR and IR in this patient population.

The Changing World of Breast Cancer: A Radiologist's Perspective

Compared with other fields of medicine, there is hardly an area that has seen such fast development as the world of breast cancer. Indeed, the way we treat breast cancer has changed fundamentally over the past decades. Breast imaging has always been an integral part of this change, and it undergoes constant adjustment to new ways of thinking. This relates not only to the technical tools we use for diagnosing breast cancer but also to the way diagnostic information is used to guide treatment. There is a constant change of concepts for and attitudes toward breast cancer, and a constant flux of new ideas, new treatment approaches, and new insights into the molecular and biological behavior of this disease. Clinical breast radiologists and even more so, clinician scientists, interested in breast imaging need to keep abreast with this rapidly changing world. Diagnostic or treatment approaches that are considered useful today may be abandoned tomorrow. Approaches that seem irrelevant or far too extravagant today may prove clinically useful and adequate next year. Radiologists must constantly question what they do, and align their clinical aims and research objectives with the changing needs of contemporary breast oncology. Moreover, knowledge about the past helps better understand present debates and controversies. Accordingly, in this article, we provide an overview on the evolution of breast imaging and breast cancer treatment, describe current areas of research, and offer an outlook regarding the years to come.

The Diagnostic Value of MR Imaging in Determining the Lymph Node Status of Patients with Non-Small Cell Lung Cancer: A Meta-Analysis

Purpose To summarize existing evidence of thoracic magnetic resonance (MR) imaging in determining the nodal status of non-small cell lung cancer (NSCLC) with the aim of elucidating its diagnostic value on a per-patient basis (eg, in treatment decision making) and a per-node basis (eg, in target volume delineation for radiation therapy), with results of cytologic and/or histologic examination as the reference standard. Materials and Methods A systematic literature search for original diagnostic studies was performed in PubMed, Web of Science, Embase, and MEDLINE. The methodologic quality of each study was evaluated by using the Quality Assessment of Diagnostic Accuracy Studies 2, or QUADAS-2, tool. Hierarchic summary receiver operating characteristic curves were generated to estimate the diagnostic performance of MR imaging. Subgroup analyses, expressed as relative diagnostic odds ratios (DORs) (rDORs), were performed to evaluate whether publication year, methodologic quality, and/or method of evaluation (qualitative [ie, lesion size and/or morphology] vs quantitative [eg, apparent diffusion coefficients in diffusion-weighted images]) affected diagnostic performance. Results Twelve of 2551 initially identified studies were included in this meta-analysis (1122 patients; 4302 lymph nodes). On a per-patient basis, the pooled estimates of MR imaging for sensitivity, specificity, and DOR were 0.87 (95% confidence interval [CI]: 0.78, 0.92), 0.88 (95% CI: 0.77, 0.94), and 48.1 (95% CI: 23.4, 98.9), respectively. On a per-node basis, the respective measures were 0.88 (95% CI: 0.78, 0.94), 0.95 (95% CI: 0.87, 0.98), and 129.5 (95% CI: 49.3, 340.0). Subgroup analyses suggested greater diagnostic performance of quantitative evaluation on both a per-patient and per-node basis (rDOR = 2.76 [95% CI: 0.83, 9.10], P = .09 and rDOR = 7.25 [95% CI: 1.75, 30.09], P = .01, respectively). Conclusion This meta-analysis demonstrated high diagnostic performance of MR imaging in staging hilar and mediastinal lymph nodes in NSCLC on both a per-patient and per-node basis. (©) RSNA, 2016 Online supplemental material is available for this article.

Management of the axilla after neoadjuvant chemotherapy for clinically node positive breast cancer: A nationwide survey study in The Netherlands

BACKGROUND

Axillary pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC) is achieved in a substantial part of clinically node positive breast cancer patients. Treatment of the axilla after NAC varies widely, and new techniques to spare patients from an axillary lymph node dissection (ALND) are being introduced.

METHODS

This Dutch nationwide survey regarding treatment of the initially clinically node positive axilla in patients receiving NAC was conducted amongst 148 surgical oncologists during November 2014-June 2015, to survey the diagnostic work-up, axillary mapping and willingness to omit ALND.

RESULTS

Axillary ultrasound was considered a standard procedure in the diagnostic work-up by 99% of participants. The majority of 70% of participants stated that ALND could possibly be omitted in node positive patients with a favourable response to NAC. A positive correlation was observed between the total amount of patients treated, versus patients receiving NAC (P < 0.01). A total of 93 respondents performed axillary response evaluation after NAC, using imaging (72%), excision of localized lymph nodes (56%) or sentinel node biopsy (SNB; 45%). Decision-making in omitting ALND was influenced by the presence of N2-3 disease, patient age and type of breast surgery. Multivariable analysis showed that clinicians who administered NAC more often, were more likely to omit ALND (P < 0.01).

DISCUSSION

The majority of surgeons are inclined to omit ALND in case of an axillary pCR. A large variety of techniques is being used to identify a pCR. The lack of consensus on this topic indicates the need for guidelines based on the best available evidence.

Simple bioconjugate chemistry serves great clinical advances: albumin as a versatile platform for diagnosis and precision therapy

Albumin is the most abundant circulating protein in plasma and has recently emerged as a versatile protein carrier for drug targeting and for improving the pharmacokinetic profile of peptide or protein based drugs. Three drug delivery technologies related to albumin have been developed, which include the coupling of low-molecular weight drugs to exogenous or endogenous albumin, conjugating bioactive proteins by albumin fusion technology (AFT), and encapsulation of drugs into albumin nanoparticles. This review article starts with a brief introduction of human serum albumin (HSA), and then summarizes the mainstream chemical strategies of developing HSA binding molecules for coupling with drug molecules. Moreover, we also concisely condense the recent progress of the most important clinical applications of HSA-binding platforms, and specify the current challenges that need to be met for a bright future of HSA-binding.

The diagnostic performance of sentinel lymph node biopsy in pathologically confirmed node positive breast cancer patients after neoadjuvant systemic therapy: A systematic review and meta-analysis

PURPOSE

To provide a systematic review and meta-analysis of studies investigating sentinel lymph node biopsy after neoadjuvant systemic therapy in pathologically confirmed node positive breast cancer patients.

METHODS

Pubmed and Embase databases were searched until June 19th, 2015. All abstracts were read and data extraction was performed by two independent readers. A random-effects model was used to pool the proportion for identification rate, false-negative rate (FNR) and axillary pCR with 95% confidence intervals. Subgroup analyses affirmed potential confounders for identification rate and FNR.

RESULTS

A total of 997 abstracts were identified and eventually eight studies were included. Pooled estimates were 92.3% (90.8-93.7%) for identification rate, 15.1% (12.7-17.6%) for FNR and 36.8% (34.2-39.5%) for axillary pCR. After subgroup analysis, FNR is significantly worse if one sentinel node was removed compared to two or more sentinel nodes (23.9% versus 10.4%, p = 0.026) and if studies contained clinically nodal stage 1-3, compared to studies with clinically nodal stage 1-2 patients (21.4 versus 13.1%, p = 0.049). Other factors, including single tracer mapping and the definition of axillary pCR, were not significantly different.

CONCLUSION

Based on current evidence it seems not justified to omit further axillary treatment in every clinically node positive breast cancer patients with a negative sentinel lymph node biopsy after neoadjuvant systemic therapy.

Current imaging of rectal cancer

Recent advances in rectal cancer surgery and treatment as well as new developments in magnetic resonance imaging (MRI) technique have led to extensive research in the field of preoperative imaging of rectal cancer and to an abundant literature. Pelvic MRI has indeed become an important part of the decision-making process for patients with rectal cancer. The aim of this article is to give current guidelines in terms of which imaging method to perform and also to review the role of imaging, with emphasis on MRI, not only for tumor primary staging but also for reevaluation of the tumor after neoadjuvant therapy, highlighting the role of new so-called "functional MR techniques". Future trends are also discussed.

Assessment of axillary lymph nodes in patients with breast cancer with diffusion-weighted MR imaging in combination with routine and dynamic contrast MR imaging

PURPOSE

To assess axillary lymph nodes in patients with breast cancer with diffusion-weighted MR imaging in combination with routine and dynamic contrast MR imaging.

MATERIALS AND METHODS

Prospective study was conducted on 65 enlarged axillary lymph nodes in 34 consecutive female patients (28-64 years: mean 51 years) with breast cancer. They underwent T2-weighted, dynamic contrast-enhanced and diffusion-weighted MR imaging of the breast and axilla using a single-shot echo-planar imaging with a b factor of 0500 and 1000 s/mm². Morphologic and quantitative parameters included ADC value of the axillary lymph node which was calculated and correlated with surgical findings.

RESULTS

The mean ADC value of metastatic axillary lymph nodes was 1.08 ± 0.21 × 10⁻³ mm²/s and of benign lymph nodes was 1.58 ± 0.14 × 10⁻³ mm²s. There was statistically difference in mean ADC values between metastatic and of benign axillary lymph nodes (P = 0.001). Metastatic nodes were associated with low ADC ≤ 1.3 (OR = 8.0), short axis/long axis (TS/LS) > 0.6 (OR = 7.0) and absent hilum (OR = 6.21). When ADC of 1.3 × 10⁻³ mm²/s was used as a threshold value for differentiating metastatic from benign axillary lymph nodes, the best result was obtained with an accuracy of 95.6%, sensitivity of 93%, specificity of 100%, positive predictive value of 100 %, negative predictive value of 87.5 % and area under the curve of 0.974. Multivariate model involving combined ADC value and TS/LS improved the diagnostic performance of MR imaging with AUC of 1.00.

CONCLUSION

We concluded that combination of diffusion-weighted MR imaging with morphological and dynamic MR imaging findings helps for differentiation of metastatic from benign axillary lymph nodes.

Tumor-induced alterations in lymph node lymph drainage identified by contrast-enhanced MRI

BACKGROUND

To use high resolution MRI lymphography to characterize altered tumor-draining lymph node (TDLN) lymph drainage in response to growth of aggressive tumors.

METHODS

Six mice bearing B16-F10 melanomas in one rear footpad were imaged by 3.0 Tesla (T) MRI before and after subcutaneous injection of Gadofosveset trisodium (Gd-FVT) contrast agent into both rear feet. Gd-FVT uptake into the left and right draining popliteal LNs was quantified and compared using Wilcoxon signed-rank test. Fluorescent dextran lymphography compared patterns of LN lymph drainage with the pattern of immunostained lymphatic sinuses by fluorescence microscopy.

RESULTS

TDLNs exhibited greater Gd-FVT uptake than contralateral uninvolved LNs, although this difference did not reach significance (P < 0.06). Foci of contrast agent consistently surrounded the medulla and cortex of TDLNs, while Gd-FVT preferentially accumulated in the cortex of contralateral LNs at 5 and 15 min after injection. Fluorescent dextran lymphography confirmed these distinct contrast agent uptake patterns, which correlated with lymphatic sinus growth in TDLNs.

CONCLUSION

3.0T MRI lymphography using Gd-FVT identified several distinctive alterations in the uptake of contrast agent into TDLNs, which could be useful to identify the correct TDLN, and to characterize TDLN lymphatic sinus growth that may predict metastatic potential.

Emerging lymphatic imaging technologies for mouse and man

The lymphatic circulatory system has diverse functions in lipid absorption, fluid homeostasis, and immune surveillance and responds dynamically when presented with infection, inflammation, altered hemodynamics, and cancer. Visualization of these dynamic processes in human disease and animal models of disease is key to understanding the contributory role of the lymphatic circulatory system in disease and to devising effective therapeutic strategies. Longitudinal, non-destructive, and repeated imaging is necessary to expand our understanding of disease progression and regression in basic science and clinical investigations. Herein we summarize recent advances in in vivo lymphatic imaging employing magnetic resonance, computed tomography, lymphoscintigraphy, and emerging optical techniques with respect to their contributory roles in both basic science and clinical research investigations.

Lymphatic system: a prospective area for advanced targeting of particulate drug carriers

INTRODUCTION

The lymphatic system has a critical role in the immune system's recognition and response to disease and it is an additional circulatory system throughout the entire body. Extensive multidisciplinary investigations have been carried out in the area of lymphatic delivery, and lymphatic targeting has attracted a lot of attention for providing preferential chemotherapy and improving bioavailability of drugs that undergo hepatic first-pass metabolism.

AREAS COVERED

This review focuses on progress in the field of lymphatic therapeutics and diagnosis. Moreover, the anatomy and physiology of the lymphatic system, particulate drug carriers and different physicochemical parameters of both modified and unmodified particulate drug carriers and their effect on lymphatic targeting are addressed.

EXPERT OPINION

Particulate drug carriers have encouraged lymphatic targeting, but there are still challenges in targeting drugs and bioactives to specific sites, maintaining desired action and crossing all the physiological barriers. Lymphatic therapy using drug-encapsulated lipid carriers, especially liposomes and solid lipid nanoparticles, emerges as a new technology to provide better penetration into the lymphatics where residual disease exists. Size is the most important criteria when designing nanocarriers for targeting lymphatic vessels as the transportation of these particles into lymphatic vessels is size dependent. By increasing our understanding of lymphatic transport and uptake, and the role of lymphatics in various diseases, we can design new therapeutics for effective disease control.