Construction of an anthropopathic abdominal phantom for accuracy validation of deformable image registration

The use of fluorescence laparoscopy in the resection of splenic tissue replantation in the right lobe of the liver: A case report and literature review

BACKGROUND

Ectopic replantation and regeneration of splenic tissue fragments following splenic trauma or splenectomy is known as replantation of splenic tissue. It typically takes place in the abdominal cavity, however, splenic tissue replantation in the liver is extremely rare and difficult to diagnose. It is often misdiagnosed as a liver tumor and removed.

CASE PRESENTATION

We present the case of a patient with a history of traumatic splenectomy 15 years prior to the replantation of splenic tissue in the liver. A 4 cm mass in the liver was found during the most recent physical examination, and a computed tomography scan indicated the possibility of a malignant tumor. The tumor was then removed using fluorescence laparoscopy.

CONCLUSION

There is a possibility of intrahepatic replantation of splenic tissue in patients who have had a splenectomy in the past, have recently discovered an intrahepatic space-occupying lesion, and do not have any high-risk factors for liver cancer. Unnecessary surgery can be avoided if 99mTc-labeled red blood cells imaging using mass puncture or radionuclide examination provides a clear preoperative diagnosis. Globally, there are no reports of the use of fluorescence laparoscopy in resecting replanted splenic tissue in the liver. Specifically, in the current case, there was no indocyanine green uptake in the mass, and only a small amount was found in the normally functioning liver tissue surrounding the tumor.

A low-cost PVC-based dual-modality kidney phantom

Phantoms are invaluable tools broadly used for research and training purposes designed to mimic tissues and structures in the body. In this paper, polyvinyl chloride (PVC)-plasticizer and silicone rubbers were explored as economical materials to reliably create long-lasting, realistic kidney phantoms with contrast under both ultrasound (US) and X-ray imaging. The radiodensity properties of varying formulations of soft PVC-based gels were characterized to allow adjustable image intensity and contrast. Using this data, a phantom creation workflow was established which can be easily adapted to match radiodensity values of other organs and soft tissues in the body. Internal kidney structures such as the medulla and ureter were created using a two-part molding process to allow greater phantom customization. The kidney phantoms were imaged under US and X-ray scanners to compare the contrast enhancement of a PVC-based medulla versus a silicone-based medulla. Silicone was found to have higher attenuation than plastic under X-ray imaging, but poor quality under US imaging. PVC was found to exhibit good contrast under X-ray imaging and excellent performance for US imaging. Finally, the durability and shelf life of our PVC-based phantoms were observed to be vastly superior to that of common agar-based phantoms. The work presented here allows extended periods of usage and storage for each kidney phantom while simultaneously preserving anatomical detail, contrast under dual-modality imaging, and low cost of materials.

Amphiphilic phospholipid-iodinated polymer conjugates for bioimaging

Amphiphilic phospholipid-iodinated polymer conjugates were designed and synthesized as new macromolecular probes for a highly radiopaque and biocompatible imaging technology. Bioconjugation of PEG 2000-phospholipids and iodinated polyesters by click chemistry created amphiphilic moieties with hydrophobic polyesters and hydrophilic PEG units, which allowed their self-assemblies into vesicles or spiked vesicles. More importantly, the conjugates exhibited high radiopacity and biocompatibility in in vitro X-ray and cell viability measurements. This new type of bioimaging contrast agent with a Mn value of 11 289 g mol-1 was found to have a significant X-ray signal at 3.13 mg mL-1 of iodine equivalent than baseline and no cytotoxicity after 48 hours incubation of with HEK and 3T3 cells at 20 μM (20 picomoles) concentration of conjugates per well. The potential of adopting the described macromolecular probes for bioimaging was demonstrated, which could further promote the development of a field-friendly and highly sensitive bioimaging contrast agent for point-of-care diagnostic applications.

Control of Direct Written Ink Droplets Using Electrowetting

Here, we investigate the feasibility and effectiveness of electrowetting in the motion control of droplets of different liquids, which are widely used as inks in direct writing (DW)-based three-dimensional (3D) printing processes for various applications. To control the movement of DW ink droplets on dielectric substrates, the electrodes were embedded in the substrate. It is demonstrated that droplets of pure liquid inks, aqueous polymer solution inks, and carbon fiber suspension inks can be moved on multi-angled surfaces. Also, experimental results reveal that droplets of a commercial hydrogel, agar-agar, alginate, xanthan gum, and gum arabic can be moved by electrowetting. Droplets of sizes 200 μm-3 mm were manipulated and moved by the electric field on different dielectric substrates accurately and repeatedly. Effective electrowetting-based control and movement of droplets were observed on horizontal, vertical, and even inverted substrates. These findings imply the feasibility and potential application of electrowetting as a flexible, rapid, and new method for ink droplet control in 3D printing processes.

Characterizing mechanical and medical imaging properties of polyvinyl chloride-based tissue-mimicking materials

Polyvinyl chloride (PVC) is a commonly used tissue‐mimicking material (TMM) for phantom construction using 3D printing technology. PVC‐based TMMs consist of a mixture of PVC powder and dioctyl terephthalate as a softener. In order to allow the clinical use of a PVC‐based phantom use across CT and magnetic resonance imaging (MRI) imaging platforms, we evaluated the mechanical and physical imaging characteristics of ten PVC samples. The samples were made with different PVC‐softener ratios to optimize phantom bioequivalence with physiologic human tissue. Phantom imaging characteristics, including computed tomography (CT) number, MRI relaxation time, and mechanical properties (e.g., Poisson’s ratio and elastic modulus) were quantified. CT number varied over a range of approximately −10 to 110 HU. The relaxation times of the T1‐weighted and T2‐weighted images were 206.81 ± 17.50 and 20.22 ± 5.74 ms, respectively. Tensile testing was performed to evaluate mechanical properties on the three PVC samples that were closest to human tissue. The elastic moduli for these samples ranged 7.000–12.376 MPa, and Poisson’s ratios were 0.604–0.644. After physical and imaging characterization of the various PVC‐based phantoms, we successfully produced a bioequivalent phantom compatible with multimodal imaging platforms for machine calibration and image optimization/benchmarking. By combining PVC with 3D printing technologies, it is possible to construct imaging phantoms simulating human anatomies with tissue equivalency.

Head and Neck Cancer Adaptive Radiation Therapy (ART): Conceptual Considerations for the Informed Clinician

For nearly 2 decades, adaptive radiation therapy (ART) has been proposed as a method to account for changes in head and neck tumor and normal tissue to enhance therapeutic ratios. While technical advances in imaging, planning and delivery have allowed greater capacity for ART delivery, and a series of dosimetric explorations have consistently shown capacity for improvement, there remains a paucity of clinical trials demonstrating the utility of ART. Furthermore, while ad hoc implementation of head and neck ART is reported, systematic full-scale head and neck ART remains an as yet unreached reality. To some degree, this lack of scalability may be related to not only the complexity of ART, but also variability in the nomenclature and descriptions of what is encompassed by ART. Consequently, we present an overview of the history, current status, and recommendations for the future of ART, with an eye toward improving the clarity and description of head and neck ART for interested clinicians, noting practical considerations for implementation of an ART program or clinical trial. Process level considerations for ART are noted, reminding the reader that, paraphrasing the writer Elbert Hubbard, "Art is not a thing, it is a way."

3D-printed breast phantom for multi-purpose and multi-modality imaging

Background

Breast imaging technology plays an important role in breast cancer planning and treatment. Recently, three-dimensional (3D) printing technology has become a trending issue in phantom constructions for medical applications, with its advantages of being customizable and cost-efficient. However, there is no current practice in the field of multi-purpose breast phantom for quality control (QC) in multi-modalities imaging. The purpose of this study was to fabricate a multi-purpose breast phantom with tissue-equivalent materials via a 3D printing technique for QC in multi-modalities imaging.

Methods

We used polyvinyl chloride (PVC) based materials and a 3D printing technique to construct a breast phantom. The phantom incorporates structures imaged in the female breast such as microcalcifications, fiber lesions, and tumors with different sizes. Moreover, the phantom was used to assess the sensitivity of lesion detection, depth resolution, and detectability thresholds with different imaging modalities. Phantom tissue equivalent properties were determined using computed tomography (CT) attenuation [Hounsfield unit (HU)] and magnetic resonance imaging (MRI) relaxation times.

Results

The 3D-printed breast phantom had an average background value of 36.2 HU, which is close to that of glandular breast tissue (40 HU). T1 and T2 relaxation times had an average relaxation time of 206.81±17.50 and 20.22±5.74 ms, respectively. Mammographic imaging had improved detection of microcalcification compared with ultrasound and MRI with multiple sequences [T1WI, T2WI and short inversion time inversion recovery (STIR)]. Soft-tissue lesion detection and cylindrical tumor contrast were superior with mammography and MRI compared to ultrasound. Hemispherical tumor detection was similar regardless of the imaging modality used.

Conclusions

We developed a multi-purpose breast phantom using a 3D printing technique and determined its value for multi-modal breast imaging studies.

An automated A-value measurement tool for accurate cochlear duct length estimation

BACKGROUND

There has been renewed interest in the cochlear duct length (CDL) for preoperative cochlear implant electrode selection and postoperative generation of patient-specific frequency maps. The CDL can be estimated by measuring the A-value, which is defined as the length between the round window and the furthest point on the basal turn. Unfortunately, there is significant intra- and inter-observer variability when these measurements are made clinically. The objective of this study was to develop an automated A-value measurement algorithm to improve accuracy and eliminate observer variability.

METHOD

Clinical and micro-CT images of 20 cadaveric cochleae specimens were acquired. The micro-CT of one sample was chosen as the atlas, and A-value fiducials were placed onto that image. Image registration (rigid affine and non-rigid B-spline) was applied between the atlas and the 19 remaining clinical CT images. The registration transform was applied to the A-value fiducials, and the A-value was then automatically calculated for each specimen. High resolution micro-CT images of the same 19 specimens were used to measure the gold standard A-values for comparison against the manual and automated methods.

RESULTS

The registration algorithm had excellent qualitative overlap between the atlas and target images. The automated method eliminated the observer variability and the systematic underestimation by experts. Manual measurement of the A-value on clinical CT had a mean error of 9.5 ± 4.3% compared to micro-CT, and this improved to an error of 2.7 ± 2.1% using the automated algorithm. Both the automated and manual methods correlated significantly with the gold standard micro-CT A-values (r = 0.70, p < 0.01 and r = 0.69, p < 0.01, respectively).

CONCLUSION

An automated A-value measurement tool using atlas-based registration methods was successfully developed and validated. The automated method eliminated the observer variability and improved accuracy as compared to manual measurements by experts. This open-source tool has the potential to benefit cochlear implant recipients in the future.