Report on the AAPM Grand Challenge on deep generative modeling for learning medical image statistics

Background

The findings of the 2023 AAPM Grand Challenge on Deep Generative Modeling for Learning Medical Image Statistics are reported in this Special Report.

Purpose

The goal of this challenge was to promote the development of deep generative models for medical imaging and to emphasize the need for their domain-relevant assessments via the analysis of relevant image statistics.

Methods

As part of this Grand Challenge, a common training dataset and an evaluation procedure was developed for benchmarking deep generative models for medical image synthesis. To create the training dataset, an established 3D virtual breast phantom was adapted. The resulting dataset comprised about 108,000 images of size 512×512. For the evaluation of submissions to the Challenge, an ensemble of 10,000 DGM-generated images from each submission was employed. The evaluation procedure consisted of two stages. In the first stage, a preliminary check for memorization and image quality (via the Fréchet Inception Distance (FID)) was performed. Submissions that passed the first stage were then evaluated for the reproducibility of image statistics corresponding to several feature families including texture, morphology, image moments, fractal statistics and skeleton statistics. A summary measure in this feature space was employed to rank the submissions. Additional analyses of submissions was performed to assess DGM performance specific to individual feature families, the four classes in the training data, and also to identify various artifacts.

Results

Fifty-eight submissions from 12 unique users were received for this Challenge. Out of these 12 submissions, 9 submissions passed the first stage of evaluation and were eligible for ranking. The top-ranked submission employed a conditional latent diffusion model, whereas the joint runners-up employed a generative adversarial network, followed by another network for image superresolution. In general, we observed that the overall ranking of the top 9 submissions according to our evaluation method (i) did not match the FID-based ranking, and (ii) differed with respect to individual feature families. Another important finding from our additional analyses was that different DGMs demonstrated similar kinds of artifacts.

Conclusions

This Grand Challenge highlighted the need for domain-specific evaluation to further DGM design as well as deployment. It also demonstrated that the specification of a DGM may differ depending on its intended use.

Investigating the robustness of a deep learning-based method for quantitative phase retrieval from propagation-based x-ray phase contrast measurements under laboratory conditions

Objective.Quantitative phase retrieval (QPR) in propagation-based x-ray phase contrast imaging of heterogeneous and structurally complicated objects is challenging under laboratory conditions due to partial spatial coherence and polychromaticity. A deep learning-based method (DLBM) provides a nonlinear approach to this problem while not being constrained by restrictive assumptions about object properties and beam coherence. The objective of this work is to assess a DLBM for its applicability under practical scenarios by evaluating its robustness and generalizability under typical experimental variations.Approach.Towards this end, an end-to-end DLBM was employed for QPR under laboratory conditions and its robustness was investigated across various system and object conditions. The robustness of the method was tested via varying propagation distances and its generalizability with respect to object structure and experimental data was also tested.Main results.Although the end-to-end DLBM was stable under the studied variations, its successful deployment was found to be affected by choices pertaining to data pre-processing, network training considerations and system modeling.Significance.To our knowledge, we demonstrated for the first time, the potential applicability of an end-to-end learning-based QPR method, trained on simulated data, to experimental propagation-based x-ray phase contrast measurements acquired under laboratory conditions with a commercial x-ray source and a conventional detector. We considered conditions of polychromaticity, partial spatial coherence, and high noise levels, typical to laboratory conditions. This work further explored the robustness of this method to practical variations in propagation distances and object structure with the goal of assessing its potential for experimental use. Such an exploration of any DLBM (irrespective of its network architecture) before practical deployment provides an understanding of its potential behavior under experimental settings.

A196 CROHN’S DISEASE PATIENT DERIVED MACROPHAGES ARE MORE SUSCEPTIBLE TO HYDROGEN PEROXIDE INDUCED CELL DEATH

Background

Crohn’s disease (CD) is characterized by intestinal inflammation due to the interplay between immunity, genetics, and environmental factors such as diet. Selenium (Se) deficiency is common in patients with CD due to malabsorption or high enteric losses. Selenium is used in the synthesis of selenoproteins that have antioxidant properties (e.g. glutathione peroxidases (GPx)) and are highly expressed in macrophages. However, how Se deficiency affects immune system function in patients with CD is unknown. We hypothesize that characterizing Se status, selenoprotein expression and subsequently macrophage function will advance knowledge of mucosal immunity and provide novel insight into CD.

Purpose

To determine if patients with active CD and healthy controls differ in Se dietary intake and status, oxidative stress, and macrophage cytotoxicity in response to oxidative stress.

Method

Blood was collected from healthy volunteers and patients diagnosed with ileal, ileocolonic or colonic CD (age ≥18 years, with mild or moderate endoscopic disease activity or fecal calprotectin ≥250 µg/g, and Harvey Bradshaw index <16, stable medications including biologics for at least 8-weeks prior to recruitment). Serum was analyzed for GPx activity, malondialdehyde (MDA) and C-reactive protein (CRP) concentrations. Monocytes were isolated by plastic adherence and treated with M-CSF (10 ng/ml, 7d) to derive macrophages. mRNA expression of GPx1, GPx4 and SelenoP was determined by qPCR. Lactate dehydrogenase release was measured in macrophages treated with 500 µM H₂O₂ for 2h.

Result(s)

Samples and/or dietary intake data were collected from 9 patients with CD (3 female, 6 male, mean age=36.8 years) and 13 controls (7 female, 6 male, mean age=27.7 years). Dietary Se intake did not differ between patients with CD and controls (126.1 ± 23.2 vs. 123.3 ± 19.8 µg/day). GPx activity was greater in the serum of patients with CD compared to controls (369 ± 49 vs. 169 ± 27 mU/mL, n=6-8, p<0.005). Patients with CD and controls did not differ in serum MDA concentration (7.80 ± 0.57 vs. 6.53 ± 1.1 µM). CRP levels correlated with serum MDA concentration in patients with CD (r=0.95, n=5, p<0.05) but not GPx activity. Macrophages from patients with CD (n=6) and controls (n=7) did not differ in expression of GPx1 and GPx4 mRNA, whereas SelenoP mRNA was ~200-fold lower in macrophages from patients with CD. Macrophages derived from patients with CD were more susceptible to H₂O₂-evoked cell death (10.3 ± 1.1 vs. 4.7 ± 0.7 % n=2-3 p<0.05).

Conclusion(s)

Despite adequate dietary Se intake our findings suggest altered Se metabolism in patients with active CD, with increases in serum GPx potentially indicative of the need for antioxidant activity to counter oxidative stress. The increased sensitivity of macrophages from patients with CD to H₂O₂ emphasizes the role of oxidative stress and redox balance in IBD. Defining how micronutrients, in this instance Se, impacts innate immunity may provide new approaches to the management of CD.

Disclosure of Interest

None Declared

Silk Fibroin Microparticle Scaffold for Use in Bone Void Filling: Safety and Efficacy Studies

Silk fibroin (SF) is a natural biocompatible protein polymer extracted from cocoons of silkworm Bombyx mori. SF can be processed into a variety of different forms and shapes that can be used as scaffolds to support bone regeneration. Three-dimensional (3D) SF scaffolds have shown promise in bone-void-filling applications. In in vitro studies, it has been demonstrated that a microparticle-based SF (M-RSF) scaffold promotes the differentiation of stem cells into an osteoblastic lineage. The expression of differentiation markers was also significantly higher for M-RSF scaffolds as compared to other SF scaffolds and commercial ceramic scaffolds. In this work, we have evaluated the in vitro and in vivo biocompatibility of M-RSF scaffolds as per the ISO 10993 guidelines in a Good Laboratory Practice (GLP)-certified facility. The cytotoxicity, immunogenicity, genotoxicity, systemic toxicity, and implantation studies confirmed that the M-RSF scaffold is biocompatible. Further, the performance of the M-RSF scaffold to support bone formation was evaluated in in vivo bone implantation studies in a rabbit model. Calcium sulfate (CaSO₄) scaffolds were chosen as reference material for this study as they are one of the preferred materials for bone-void-filling applications. M-RSF scaffold implantation sites showed a higher number of osteoblast and osteoclast cells as compared to CaSO₄ implantation sites indicating active bone remodeling. The number density of osteocytes was double for M-RSF scaffold implantation sites, and these M-RSF scaffold implantation sites were characterized by enhanced collagen deposition, pointing toward a finer quality of the new bone formed. Moreover, the M-RSF scaffold implantation sites had a negligible incidence of secondary fractures as compared to the CaSO₄ implantation sites (∼50% sites with secondary fracture), implying a reduction in postsurgical complications. Thus, the study demonstrates that the M-RSF scaffold is nontoxic for bone-void-filling applications and facilitates superior healing of fracture defects as compared to commercial calcium-based bone void fillers.

Silk fibroin and ceramic scaffolds: Comparative in vitro studies for bone regeneration

Synthetic bone void fillers based on calcium ceramics are used to fill cavities in the bone and promote bone regeneration. More recently, silk fibroin (SF), a protein polymer obtained from Bombyx mori silkworm, has emerged as a promising material in bone void filling. In this work, we have compared the safety and efficacy of two types of silk fibroin-based bone void fillers with currently used and commercially available ceramic bone void fillers (based on calcium sulphate, beta tricalcium phosphate, and beta tricalcium phosphate with hydroxyapatite). Further, we have also evaluated these two types of SF scaffolds, which have strikingly different structural attributes. The biocompatibility of these scaffolds was comparable as assessed by cytotoxicity assay, cellular adhesion assay, and immunogenic assay. Ability of the scaffolds to support differentiation of human mesenchymal stem cells (hMSCs) into an osteoblastic lineage was also evaluated in an in vitro differentiation experiment using reverse transcriptase polymerase chain reaction analysis. These results revealed that cells cultured on SF scaffolds exhibit higher expression of early to late markers such as Runx2, BMPs, collagen, osterix, osteopontin, and osteocalcin as compared with ceramic-based scaffolds. This observation was further validated by studying the expression of alkaline phosphatase and calcium deposition. We also show that scaffolds made from same material of SF, but characterized by very different pore architectures, have diverse outcome in stem cell differentiation.

Metasurface-enabled broadband beam splitters integrated with quarter-wave plate functionality

Conventional beam splitters and wave plates, while being essential components in diverse optical systems, require considerable space, especially when used in combination. Here, we designed and experimentally demonstrated metasurface-enabled efficient broadband beam splitters integrated with quarter-wave plate (QWP) functionality for simultaneous power splitting and circular-to-linear polarization conversion in the near-infrared range. By utilizing two different gap-plasmon meta-atoms, which function as QWPs performing efficient circular-to-linear polarization conversion and provide the phase difference of π between reflected linearly polarized beams, we designed a metasurface that completely suppress the specular reflection (zero-order diffraction) and second-order diffraction, while ensuring efficient and equal beam splitting of a circularly polarized wave into two reflected beams with predesigned directions and well-defined linear-polarization states in the wavelength range of 750-950 nm. The fabricated metasurface exhibits excellent performance of circular-to-linear conversion and power splitting, with efficient suppression of specular reflection (<1%) and splitting efficiencies above 50% for both right and left circularly polarized excitation at the design wavelength of λ = 850 nm. By enabling the combined functionalities of a conventional beam splitter and a QWP, our approach opens up new prospects for advanced research and applications targeting photonics integration and miniaturization.

Characterization of urethral fibrosis in a rabbit model: Potential roles of Wnt-β catenin pathway and epithelial to mesenchymal transition

AIM

To elucidate the precise cellular and molecular mechanisms that underlie urethral fibrogenesis.

METHODS

Endoluminal electrocautery injury (using Karl Storz 10 Fr. Pediatric urethroscope) was employed in male rabbits (n = 6) to create mucosal injury. Retrograde urethrogram (RUG) and endoluminal ultrasound techniques were used to assess severity and changes in luminal cross-sectional area. Six control rabbits were subjected to sham injury, in which the electrocautery was inserted but not powered. Urethral tissues were harvested 30 days postinjury and subjected to RNA sequencing and quantitative polymerase chain reaction (qPCR) to determine changes in gene expression. Histological, immunostaining, and Western blot studies were used to determine changes in protein expression of known markers of fibrosis (eg, collagen, Integrinαv, GIV/Girdin, transforming growth factor-β (TGF-β), and pSMAD1,2,3).

RESULTS

Trichrome staining confirmed increased connective tissue in urethral scar tissues. Immunostaining revealed a potential role for epithelial to mesenchymal cell transition (EMT) and positive labeling for all fibrotic markers (eg, collagen-1, Integrin αv, GIV/Girdin, transforming growth factor-β (TGF-β), and SMAD1,2,3). Western blot analysis confirmed increased protein levels of these fibrotic markers.

CONCLUSION

Our RNA sequencing and qPCR studies, in conjunction with our protein data, suggest that urethral mucosal fibrogenesis may be mediated by novel fibrogenic signaling pathways involving Wnt-β catenin, TGF-β, GIV/Girdin, and EMT which lead to increased collagen deposition. Therapeutic strategies targeting these pathways may be beneficial in attenuating fibrogenesis and stricture progression.

Direct Characterization of Near-Field Coupling in Gap Plasmon-Based Metasurfaces

Metasurfaces based on gap surface-plasmon resonators allow one to arbitrarily control the phase, amplitude, and polarization of reflected light with high efficiency. However, the performance of densely packed metasurfaces is reduced, often quite significantly, in comparison with simple analytical predictions. We argue that this reduction is mainly because of the near-field coupling between metasurface elements, which results in response from each element being different from the one anticipated by design simulations, which are commonly conducted for each individual element being placed in an artificial periodic arrangement. In order to study the influence of near-field coupling, we fabricate meta-elements of varying sizes arranged in quasi-periodic arrays so that the immediate environment of same size elements is different for those located in the middle and at the border of the arrays. We study the near-field using a phase-resolved scattering-type scanning near-field optical microscopy (s-SNOM) and conducting numerical simulations. By comparing the near-field maps from elements of the same size but different placements we evaluate the near-field coupling strength, which is found to be significant for large and densely packed elements. This technique is quite generic and can be used practically for any metasurface type in order to precisely measure the near-field response from each individual element and identify malfunctioning ones, providing feedback to their design and fabrication, thereby allowing one to improve the efficiency of the whole metasurface.

Establishment of an in ovo chick embryo yolk sac membrane (YSM) assay for pilot screening of potential angiogenic and anti-angiogenic agents

Angiogenesis, the process of new blood vessel formation from pre-existing vessels, is essential for growth and development. Development of drugs that can accelerate or decelerate angiogenesis in the context of various diseases requires appropriate preclinical screening. As angiogenesis involves complex cellular and molecular processes, in vivo studies are superior to in vitro investigations. Conventional in vitro, in vivo, and ex ovo models of angiogenesis are time consuming and tedious, and require sophisticated infrastructure for embryo culture. In the present study, we established an in ovo chick embryo yolk sac membrane (YSM) assay for angiogenesis and tested the angiogenic potential of arginine, conditioned medium (CM) from human adipose tissue and placenta-derived mesenchymal stem cells (ADMSCs-CM and PDMSCs-CM), avastin and vitamin C. The obtained results were confirmed with the routinely employed chick embryo Chorioallantoic Membrane (CAM) assay. Both assays revealed the pro-angiogenic nature of arginine, ADMSCs-CM, and PDMSCs-CM, and the anti-angiogenic effect of avastin and vitamin C. This novel in ovo YSM model is simple, reproducible, and highly economic in terms of the time frame and cost incurred. The proposed model is thus a suitable substitute to the CAM model for pilot screening of potential angiogenic and anti-angiogenic agents.

Matrix-entrapped cellular secretome rescues diabetes-induced EPC dysfunction and accelerates wound healing in diabetic mice

Cellular secretory products have infinite potential, which is only recently explored for research and therapeutic applications. The present study elaborated on the formation of a unique matrix-entrapped cellular secretome (MCS), a hydrogel-like secretome produced by bone marrow-derived mononuclear cells when cultured on a three-dimensional electrospun nanofiber matrix under specific conditions. These culture conditions support the growth of a mixed population predominantly comprising of endothelial precursor cells (EPCs), along with mesenchymal stromal cells and pericytes. Interestingly, such secretome is not formed in a pure culture of EPCs on the similarly formulated matrix, suggesting that a heterotypic cell-cell interaction is essential for the formation of MCS. In addition, the specific composition of the matrix was found to be a critical necessity for the formation of MCS. Furthermore, the application of the MCS as a substrate promotes the growth of EPCs in culture. It also rescues the diabetes-induced EPC dysfunction as assessed based on the parameters, such as viability, proliferation, colony formation, cellular adhesion, chemotactic migration, and tubule formation. MCS augments the levels of eNOS-specific mRNA (Nos3) and also promotes the restoration of the SDF1/CXCR4 axis in diabetic EPCs. Notably, a topical application of MCS on diabetic wounds leads to an accelerated wound closure. Thus, the current data showed that MCS forms an excellent cell-free biomaterial in the treatment of diabetic wounds and non-healing ulcers.

Bifunctional gap-plasmon metasurfaces for visible light: polarization-controlled unidirectional surface plasmon excitation and beam steering at normal incidence

Integration of multiple diversified functionalities into a single, planar and ultra-compact device has become an emerging research area with fascinating possibilities for realization of very dense integration and miniaturization in photonics that requires addressing formidable challenges, particularly for operation in the visible range. Here we design, fabricate and experimentally demonstrate bifunctional gap-plasmon metasurfaces for visible light, allowing for simultaneous polarization-controlled unidirectional surface plasmon polariton (SPP) excitation and beam steering at normal incidence. The designed bifunctional metasurfaces, consisting of anisotropic gap-plasmon resonator arrays, produce two different linear phase gradients along the same direction for respective linear polarizations of incident light, resulting in distinctly different functionalities realized by the same metasurface. The proof-of-concept fabricated metasurfaces exhibit efficient (>25% on average) unidirectional (extinction ratio >20 dB) SPP excitation within the wavelength range of 600-650 nm when illuminated with normally incident light polarized in the direction of the phase gradient. At the same time, broadband (580-700 nm) beam steering (30.6°-37.9°) is realized when normally incident light is polarized perpendicularly to the phase gradient direction. The bifunctional metasurfaces developed in this study can enable advanced research and applications related to other distinct functionalities for photonics integration.

Third-order gap plasmon based metasurfaces for visible light

Efficient control and manipulation of light using metasurfaces requires high fabrication accuracy that becomes progressively demanding when decreasing the operation wavelength. Considering gap surface plasmon (GSP) based metasurfaces, we demonstrate that the metasurfaces, which utilize the third-order GSP resonance and thereby involve relatively large nanobricks, can successfully be used for efficient polarization-controlled steering of visible light. The reflection amplitude and phase maps for a 450 nm period array of 50 nm thick nanobricks placed atop a 40 nm thick silica layer supported by an optically thick gold film are calculated for the operation wavelength of 633 nm. Exploiting the occurrence of the third-order GSP resonance for nanobricks having their lengths close to 300 nm, we design the phase-gradient metasurface, representing an array of (450 x 2250 nm²) supercells made of 5 nanobricks with different dimensions, to operate as a polarization beam splitter for linearly polarized light. The fabricated polarization beam splitter is characterized using a supercontinuum light source at the normal light incidence and found to exhibit a polarization contrast ratio of up to 40 dB near the design wavelength of 633 nm while showing better than 20 dB contrast in the range of 550 - 650 nm for both polarizations. The diffraction efficiency experimentally measured at normal incidence exceeds 10% (20% in simulations) at the design wavelength of 633 nm, with the performance for the TE polarization (electric field perpendicular to the plane of diffraction) being significantly better (experimentally > 20% and theoretically > 40%) than for the TM polarization. This difference becomes even more pronounced for the light incidence deviating from normal. Finally, we discuss possible improvements of the performance of polarization beam splitters based on third-order GSP resonance as well as other potential applications of the suggested approach.

Efficacy of C.E.R.A. in Routine Clinical Practice for Correction of Anaemia and Maintenance of the Haemoglobin Levels in CKD Patients not on Dialysis

INTRODUCTION

C.E.R.A. reported effective correction of anaemia and was well tolerated in International studies on CKD patients not on dialysis.

OBJECTIVE

The study aimed to describe the management of renal anaemia in CKD patients not on dialysis with C.E.R.A. in routine clinical practice in India.

METHODS

This was a prospective, single-arm, open-label, multi-centre, non-interventional, Phase IV study which followed 108 CKD Stage III-IV patients, not on dialysis with Hb < 10 g/dL for correction of anaemia with C.E.R.A.

RESULTS

Of the 108 patients with Hb < 10 g/dL at baseline, 83 (90.2%) patients achieved target Hb of 10-12 g/dL and the time taken to achieve correction of anaemia was 9.6 weeks ± 6.13 weeks in the Intent-to-treat population. Haemoglobin concentration increased from 8.59 ± 0.808 g/dL pre-therapy to 10.91 ± 0.634 g/dL post-therapy. The change in mean ± SD Hb value was 2.32 ± 0.174 g/dL. Maintenance of Hb levels within the target range of Hb 10 - 12 g/dL was observed in 78.2% of ITT and 80.8% of the PP population for mean duration of 16.69 weeks. Four patients (3.7%) experienced 5 AEs and 2 patients (1.9%) experienced 3 SAEs in the safety population. As per the treating physician none of the AEs or SAEs was considered related to study drug. There were no deaths reported.

CONCLUSIONS

This study demonstrated successful correction of anaemia in Indian patients with C.E.R.A. treatment as well as maintenance of Hb levels within the target range. C.E.R.A. was well tolerated with no new safety concerns specific to the Indian population. The less frequent up to monthly dosing schedule of C.E.R.A. may offer clinicians and patients a simplified regimen of anaemia management as compared to traditional frequently administered (thrice weekly to once weekly) ESAs.

A nano zinc oxide doped electrospun scaffold improves wound healing in a rodent model

Development of new and effective wound dressing materials continues to be an area of intense research in wound care management. ​Fabricated ZnO doped nanofibrous scaffold exhibited proficiency in EPCs enrichment and wound healing.

A comparison of diagnostic imaging modalities for colorectal liver metastases

AIMS

The aims of this study were to compare the diagnostic performance of CT scan, MR liver, PET-CT and intra-operative ultrasound (IOUS) for the detection of liver metastases against the histopathological findings, and to compare PET-CT with CT for the detection of distant disease in metastatic colorectal cancer patients eligible for surgical treatment.

METHODS

A prospective study was performed that measured concordance between the number and stage of metastatic lesions identified with various preoperative imaging modalities and histology of patients undergoing surgical treatment for CRLM.

RESULTS

Compared with histopathology, concordance for the number of metastatic liver lesions was moderate for CT scan (K = 0.477, 95% CI: 0.28-0.66), moderate for MR scan (K = 0.574, 95% CI: 0.39-0.75), good for FDG PET-CT (K = 0.703, 95% CI: 0.52-0.87) and very good for IOUS (K = 0.904, 95% CI: 0.81-0.99). Additional CRLM were identified intraoperatively in six patients (9.1%) with IOUS and in 7.5% of the cases surgical strategy was changed according to the new intraoperative findings. The diagnosis of intra abdominal lymph node metastatic disease was made with PET-CT only in nine patients (13.6%)

DISCUSSION

Our study supports the recent recommendations of the Oncosurg Multidisciplinary International Consensus regarding the importance of high quality CT and MR in the staging of CRLM but provides further evidence for the added value of PET-CT, especially in detecting extrahepatic intra-abdominal metastatic disease that may be amenable to potentially curative resection. Despite these advances in preoperative staging, there still remains a role for IOUS in detecting additional metastases at the time of surgery.

Measurement of fetal fat in utero in normal and diabetic pregnancies using magnetic resonance imaging

OBJECTIVES

To assess the reliability of magnetic resonance imaging (MRI) to measure fetal fat volume in utero, and to study fetal growth in women with and without diabetes in view of the increased prevalence of macrosomia in the former.

METHODS

We studied 26 pregnant women, 14 with pre-gestational diabetes and 12 non-diabetic controls. Fetal assessment took place at 24 weeks' gestation and again at 34 weeks by standard ultrasound biometry followed by MRI at 1.5 T. Fetal fat volume was determined from T1-weighted water-suppressed images using a semi-automated approach based on pixel intensity and taking into account partial volume effects. Fetal volume was also determined from the MRI images. Fetal weight was calculated using published fat and lean tissue densities.

RESULTS

There was little fetal fat at 24 weeks' gestation, but at 34 weeks the fetal fat content was considerably higher in the women with diabetes, with a mean fat content of 1090 ± 417 cm(3) compared with 541 ± 348 cm(3) in the controls (P = 0.006). Measurements of fetal fat volume showed low intra- and interobserver variability at 34 weeks, with intraclass correlation coefficients consistently above 0.99. Birth-weight centile correlated with fetal fat volume (R(2)  = 0.496, P < 0.001), percentage of fetal fat (R(2)  = 0.362, P = 0.008) and calculated fetal weight (R(2)  = 0.492, P < 0.001) at 34 weeks.

CONCLUSIONS

MRI appears to be a promising tool for the determination of fetal fat, body composition and weight in utero during the third trimester of pregnancy.

Enhanced growth of endothelial precursor cells on PCG-matrix facilitates accelerated, fibrosis-free, wound healing: a diabetic mouse model

Diabetes mellitus (DM)-induced endothelial progenitor cell (EPC) dysfunction causes impaired wound healing, which can be rescued by delivery of large numbers of 'normal' EPCs onto such wounds. The principal challenges herein are (a) the high number of EPCs required and (b) their sustained delivery onto the wounds. Most of the currently available scaffolds either serve as passive devices for cellular delivery or allow adherence and proliferation, but not both. This clearly indicates that matrices possessing both attributes are 'the need of the day' for efficient healing of diabetic wounds. Therefore, we developed a system that not only allows selective enrichment and expansion of EPCs, but also efficiently delivers them onto the wounds. Murine bone marrow-derived mononuclear cells (MNCs) were seeded onto a PolyCaprolactone-Gelatin (PCG) nano-fiber matrix that offers a combined advantage of strength, biocompatibility wettability; and cultured them in EGM2 to allow EPC growth. The efficacy of the PCG matrix in supporting the EPC growth and delivery was assessed by various in vitro parameters. Its efficacy in diabetic wound healing was assessed by a topical application of the PCG-EPCs onto diabetic wounds. The PCG matrix promoted a high-level attachment of EPCs and enhanced their growth, colony formation, and proliferation without compromising their viability as compared to Poly L-lactic acid (PLLA) and Vitronectin (VN), the matrix and non-matrix controls respectively. The PCG-matrix also allowed a sustained chemotactic migration of EPCs in vitro. The matrix-effected sustained delivery of EPCs onto the diabetic wounds resulted in an enhanced fibrosis-free wound healing as compared to the controls. Our data, thus, highlight the novel therapeutic potential of PCG-EPCs as a combined 'growth and delivery system' to achieve an accelerated fibrosis-free healing of dermal lesions, including diabetic wounds.

Rarer in a rare

Though moya moya disease is a disease of Asian origin, it is one of the very rare causes of stroke in India. It is a rare disease mainly characterized by progressive cerebrovascular episode due to the slowly progressive stenosis of supraclinoid segment of bilateral internal carotid arteries, the anterior and the middle cerebral arteries, and very rarely, posterior cerebral arteries. We hereby report a case of a young female who presented to us with the psychiatric complaints and refractory headache since her childhood. Therefore, we are reporting rarer (headache and neuropsychiatric) manifestations in the rare (moya moya) disease.

Influence of γ-radiation on the structure and function of soybean trypsin inhibitor

Soybean trypsin inhibitor (STI) is a known antinutrient and food allergen present in soybean. γ-Radiation has the potential to inactivate the TI protein. However, a systematic study on the influence of different moisture levels during γ radiation on structure and function of the molecule has not been reported. Pure STI was irradiated up to 200 kGy, in dry state, with 50% moisture and in aqueous solution. The radiation damage in molecular structure was assessed using, SDS-PAGE, size exclusion chromatography, fluorescence measurement, and circular dichroism, while functional damage was assessed by the TI assay. In aqueous solution, both the structure and function of TI were almost destroyed at the 10 kGy dose. While with 50% moisture and in dry state, the loss in functional and structural attributes was discernible only at 30 and 100 kGy, respectively. The TI activity was found to be unaffected in dry and soaked seeds of soybean as well as other legumes up to irradiation doses of 100 and 50 kGy, respectively.

P2-08-11: Correlation of Mammography, Ultrasound and MRI in Patients with Nipple Discharge

BACKGROUND: Breast cancer mainly originates in the epithelial lining of milk ducts or lobules. Once early pre-malignant or malignant changes occur in the ductal lining there is a long latent period before they manifest symptoms or are detected on imaging. Symptomatic nipple discharge (SND) is a common symptom noted in approximately 5% of patients. Although, usually benign it may be the earliest sign of cancer. The current standard evaluation of patients with nipple discharge includes clinical examination (CE), mammography (MMG) and ultrasound (US). Contrast enhanced MRI is considered the most sensitive imaging modality for the breast and reports suggest it may be of benefit in the evaluation of nipple discharge. We have combined MRI with standard evaluation in an ongoing prospective study to determine its utility in patients with SND.

PATIENTS AND METHODS: Between July 2004 and 31st May 2011, 75 women underwent surgery for SND. All were initially evaluated by CE, MMG and US following which a contrast enhanced breast MRI was requested. MRI was performed on a 1.5T MR unit using a dedicated breast coil. A STIR sequence in the coronal and sagittal planes along with an unenhanced fat-suppressed T1 W sequence was used to evaluate the ducts. The imaging findings were used to direct surgical excision. All specimens were oriented and evaluated by the pathologist by sectioning at 1 cm interval, from the ductal end to the periphery. The results of preoperative MMG, US and MRI findings were compared with pathology.

RESULTS: The incidence of cancer in this series was 29% and high risk lesions were noted in 43%. MMG and US were performed in 75 patients. MRI was requested in all 75 patients but could be performed in 64. MRI proved to be the most sensitive technique for detection of an abnormality in the breast (92%) compared to MMG 25%, and US 63%. MMG, US and MRI were suggestive of benign change in 64 (85%), 65 (87%) and 43 (67%) patients respectively, of which 14 (22%), 15 (23%) and 7 (16%) were malignant on pathology. MMG, US and MRI reported suspicious change in 11(15%), 10 (13%) and 21(33%) patients respectively of which 8 (73%), 7 (70%) and 9 (43%) patients had cancer on pathology. MRI had the highest sensitivity for malignancy (54%) compared to MMG (36%) and US (32%) but MRI had a low specificity (74%) (MMG 94%; US 94%). However, MRI had a high negative predictive value (86%) (MMG 78%; US 73%). Of the 22 patients with cancers, 12 were deemed to be normal on CE, MMG and US examination. Thus standard evaluation would have missed 54% of the cancers detected in this series.

CONCLUSIONS: Nipple discharge is associated with significant incidence of cancer and high risk changes. The majority of these are missed on standard evaluation (CE, MMG, US). MRI is the most sensitive method for the detection of an abnormality in these patients. It defines the location and extent of the abnormality and can guide surgical excision. However, MRI is unable to accurately differentiate malignant from benign lesions. Hence, excision of an identified abnormality and pathological evaluation remains essential.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-08-11.