RU2725075C2 - Three-dimensional modeling method for 3d printing when planning pancreatic resection in patients with tumor involvement - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: invention refers to medicine, radiation diagnostics and can be used for 3D modeling for 3D printing when planning resections of pancreas in patients with tumor involvement. It is followed by CT with intravenous bolus contrast enhancement of hepatopancreatibiliary zone by low-dose protocol to obtain phases of maximum density gradient in arteries and veins of portal system. Obtained CT images are loaded into Myrian program and anatomical segmentation of image is performed. In the first phase of contrast amplification, the arterial bed is separated, in the second phase – the portal system. 3D area of interest is created and an automatic "hepatic artery" protocol is used to isolate the arteries of the celiac-mesenterial system, as well as an automatic protocol for the portal vein "portal vein, solid filter" separation. Pancreas is separated into a phase of maximum gradient with surrounding healthy tissues. Further, the tumor is recovered using the three-dimensional interpolation method with delineation of the formation at several levels depending on the size and shape. Obtained areas of interest: arteries, veins, and tumor are displayed on one screen of three-dimensional rendering called "surface area of interest" by transportation of missing object from other phase of contrast amplification. Obtained virtual model is evaluated for presence of errors in the image by comparison with axial CT sections. Further, the obtained three-dimensional model is stored in segmentation format and loaded into the Materialize program to create a three-dimensional printing file STL-file. Obtained file is loaded into 3D print program FlashPrint and sent to 3D printer FlashForge Dreamer. On the obtained three-dimensional model, supporting structures which were created automatically in FlashPrint are deleted.EFFECT: method provides planning of pancreatic resections in patients with tumor involvement by printing a three-dimensional model of the region of interest.1 cl, 11 dwg, 1 ex

Description

The invention relates to medicine, radiation diagnostics and can be used as part of personalized medicine when planning surgical intervention in patients with tumor lesion of the pancreas.

Currently, one of the basic principles of modern surgical oncology is the implementation of functionally sparing and organ-preserving surgical interventions. In case of tumor damage to the pancreas, the radicality of the surgical intervention depends on resectability, one of the main issues of which is the involvement of vascular structures. Recently, tumors that were previously recognized as unresectable due to vascular invasion are susceptible to surgical treatment due to vascular reconstructions. In the case of this type of surgical intervention on the pancreas, the surgeon needs to provide the most informative and close to the classical anatomical aids data on the individual vessel structure of the celiac-mesenteric basin and their relationship with the tumor. The data of classical axial tomograms, multiplanar and curvilinear reconstructions, as well as volumetric rendering are inferior to the three-dimensional model printed by 3D printing.

The data obtained during the standard protocol of multiphase CT of the abdominal cavity do not have the necessary characteristics for the semi-automatic segmentation of the hepato-pancreatic-biliary zone, namely the highest density gradient of tissues (arteries and veins), since:

- there are no phases of maximum density of the contrast agent in the vessels, which complicates semi-automatic segmentation, leading to an increase in processing time;

- the attenuation coefficients of x-ray radiation of the contrasted blood in the lumens of arteries and veins with a standard scanning protocol with a voltage of 120 kV on the x-ray tube are lower than with a low dose protocol with a voltage of 100 kV, which complicates the modeling.

There are no world literature data on 3D printing of blood vessels of the celiac-mesenteric basin and pancreatic tumor. There are single publications only on the topic of virtual modeling of the hepatopancreatic-biliary zone with standard settings for the protocol of abdominal CT (Grenacher L., Thorn M., Knaebel HP., Vetter M., Hassenpflug P., Kraus T., Meinzer HP., Buchler MW, Kauffmann GW, Richter GM The role of 3-D imaging and computer-based postprocessing for surgery of the liver and pancreas. Rofo 2005; 177: 1219-1226; Klaub M, Schobinger M, Wolf I., Werner J. , Meinzer HP., Kauczor HU., Grenacher L. Value of three-dimensional reconstructions in pancreatic carcinoma using multidetector CT: Initial results. World J Gastroenterol 2009 December 14; 15 (46): 5827-5832). The advantage of this technique in comparison with virtual three-dimensional modeling is to obtain a “living model” of the area of future surgery in a 1: 1 scale.

The disadvantages include the additional time and financial costs of printing a virtual three-dimensional model.

The technical result of the claimed invention is to obtain CT images with the largest density gradient between structures for the fastest and most accurate segmentation to create a virtual model in STL format directed to 3D printing.

The specified technical result is achieved due to the fact that, as in the known method, CT is performed with an intravenous bolus contrast enhancement of the hepatopancreatobiliary zone according to the low-dose protocol to obtain phases of the highest density gradient in the arteries and veins of the portal system.

A feature of the proposed method is that the obtained CT images are loaded into the Myrian program and anatomical image segmentation is performed, the arterial bed is extracted in the first phase of contrast enhancement, the portal system is created in the second phase, a 3D area of interest is created and the hepatic artery automatic protocol is used to isolate arteries of the celiac arteries pool, as well as the automatic protocol for portal portal vein isolation “portal vein, solid filter”, pancreas formation is isolated in the phase of the greatest gradient with surrounding healthy tissues, then the tumor is isolated using three-dimensional interpolation with contouring of the formation at several levels depending from the size and shape, the obtained areas of interest: arteries, veins, and tumor are displayed on one screen of a three-dimensional rendering called “surface area of interest” by transporting the missing object from another phase of contrast enhancement, the resulting virtual model is assessed for errors in the image by comparing it with axial CT slices, then the resulting three-dimensional model is saved in a segmentation format and loaded into the Materialize program to create a three-dimensional print file. STL file, the resulting file is downloaded to the FlashPrint 3D printing program and sent to 3D Printer FlashForge Dreamer, on the obtained three-dimensional model, remove supporting structures that were created automatically in FlashPrint.

The method is illustrated by a detailed description, clinical example and illustrations, which depict:

FIG. 1 - loading CT scan into the Myrian program through the “Standard CT” protocol.

FIG. 2 - selection of the arterial phase of contrast enhancement.

FIG. 3 - adding a new region of interest to highlight arteries in the left window of the program in the graph field of interest, using the “hepatic artery” tool.

FIG. 4 - selection of the arteries of the celiac-arterial basin with the “area of interest” tool, and displaying the result in the lower right window (the surface area of interest is included in the upper tab on the left).

FIG. 5 - adding a new area of interest for highlighting the portal vein (in the left window of the program, in the column of interest, the tool "portal vein, solid filter" is selected).

FIG. 6 - transportation through the left window of the program (by right-clicking on the elements of the region of interest) data on the isolation of the portal vein in the arterial phase, as well as the selection of the pancreatic tumor in the arterial phase with the display of the elements of the virtual model together.

FIG. 7 - removal of excessively selected elements in a three-dimensional image using the “extrusion” tool in the “surface area of interest” mode.

FIG. 8 - series with segmentation data.

FIG. 9 - loading segmentation data into the Materialize program and then saving it in STL format.

FIG. 10 - result of printing an STL file on a 3D printer

The method is as follows.

On a CT scanner, a study is performed using a bolus tracking system. The voltage on the tube is set to 100 kV. The bolus tracking scan is set at the level of the thoracoabdominal aorta by highlighting the region of interest (ROI) on the axial tomogram. When the value of the attenuation coefficient (KO) of the x-ray radiation inside the ROI + 160HU is performed, the scanning is automatically started with a minimum delay of 5 seconds to obtain an early arterial phase. The portal phase is performed at 37 seconds from the start of the scan. The data obtained for each phase in the form of the first and second post-contrast series of axial tomograms are reconstructed with a reconstruction thickness of 0.625 mm using a hybrid reconstruction filter.

Next, CT images are loaded into the Myrian program, anatomical image segmentation is performed, the arterial bed is isolated in the first phase of contrast enhancement, and the portal system is in the second phase. For this, a 3D region of interest is created and the automatic protocol “hepatic artery” is used to isolate the arteries of the celiac arteries pool, as well as the automatic protocol “portal vein, solid filter” to isolate the portal vein. The formation of the pancreas is distinguished in the phase of the greatest gradient with the surrounding healthy tissues. The pancreatic tumor is isolated using the method of three-dimensional interpolation with contouring of the formation at several levels depending on the size and shape. The resulting areas of interest (arteries, veins, swelling) are displayed on a single three-dimensional rendering screen called “surface area of interest” by transporting the missing object from another phase of contrast enhancement. The resulting virtual model is evaluated for the presence of errors in the image by comparison with axial CT slices. Upon successful segmentation, the three-dimensional model is saved in the segmentation format, which is loaded into the Materialize program to create a three-dimensional print file (STL file). This file is loaded into the 3D printing program FlashPrint for sending to the 3D printer FlashForge Dreamer. After that start printing. Next, a three-dimensional model is analyzed for the presence of supporting structures, which are subsequently removed.

Our proposed method for three-dimensional reconstruction of the hepatopancreatic-biliary zone with subsequent 3D printing is based on performing a low-dose CT scan in the two-phase spiral scan mode to obtain early arterial and portal phases, post-processing image processing in the Myrian program (Intrasense, France), and creating a virtual three-dimensional model and STL file in Materialize, and, finally, sending the resulting file to a 3D printer via FlashPrint to a FlashForge Dreamer printer.

Clinical example.

Patient K., 67 years old, pancreatic head formation (adenocarcinoma), condition after chemotherapy, positive dynamics in the form of a decrease in the size of the formation. Prepared for surgery in the amount of pancreatoduodenal resection.

On a CT scanner (GE Optima 660 (128-row tomograph with a single row thickness of 0.4 mm), a study was performed using a bolus tracking system.

The voltage on the tube is set to 100 kV. The bolus tracking scan is set at the level of the thoracoabdominal aorta by highlighting the region of interest (ROI) on the axial tomogram. When the value of the attenuation coefficient (KO) of the x-ray radiation inside the ROI + 160HU is performed, the scanning is automatically started with a minimum delay of 5 seconds to obtain an early arterial phase. The portal phase is performed at 37 seconds from the start of the scan. The data obtained for each phase in the form of the first and second post-contrast series of axial tomograms are reconstructed with a reconstruction thickness of 0.625 mm using a hybrid reconstruction filter.

The resulting image was loaded into the Myrian program (Fig. 1) and anatomical image segmentation was performed; in the first phase of contrast enhancement, the arterial bed was isolated (Fig. 2, Fig. 3, Fig. 4), in the second phase, the portal system (Fig. 5) . To do this, create a 3D region of interest and use the automatic protocol “hepatic artery” (Fig. 3) to isolate the arteries of the celiac arteries pool, as well as the automatic protocol “portal vein, solid filter” (Fig. 3) to isolate the portal vein. The formation of the pancreas is distinguished in the phase of the greatest gradient with the surrounding healthy tissues using the “crowding out” tool. The pancreatic tumor was isolated using the method of three-dimensional interpolation with contouring of the formation at several levels depending on the size and shape. The obtained areas of interest (arteries, veins, swelling) are displayed on a single three-dimensional rendering screen called “surface area of interest” by transporting the missing object from another phase of contrast enhancement (Fig. 6, Fig. 7). The resulting virtual model is evaluated for the presence of errors in the image by comparison with axial CT slices. Upon successful segmentation, the three-dimensional model is saved in the segmentation format (Fig. 8), which is loaded into the Materialize program (Fig. 9) to create a three-dimensional print file (STL file). This file is loaded into the 3D printing program FlashPrint for sending to the 3D printer FlashForge Dreamer. After that start printing. Next, the three-dimensional model is analyzed for the presence of supporting structures, which are subsequently removed (Fig. 10, Fig. 11).

A three-dimensional model of a tumor of the pancreas and blood vessels can be used in abdominal surgery when planning surgical intervention to assess the location of the tumor and the possibility of its resection. It is of particular benefit when planning pancreatic resections in patients with rare variants of the vessel structure of the celiac-mesenteric basin, when the anatomical and topographic relationship of the tumor with the vessels can impede the course of the operation, affect the total time of its duration and, as a result, increase the time of anesthesiology, blood loss and etc. In addition, the 3D model has an indispensable advantage over two-dimensional images, virtual three-dimensional reconstructions and pathological preparations for the training of students, residents, as it clearly demonstrates the features of a particular anatomical structure.

Thus, the proposed technique has the following advantages: easy to perform; has a low radiation dose; does not require a lot of time for preparation and post-processor processing; allows to obtain data on the area of interest on a printed 3D model, scale 1: 1.

Claims (1)

A three-dimensional modeling method for 3D printing when planning pancreatic resections in patients with tumor lesions, including CT with an intravenous bolus contrast enhancement of the hepatopancreatobiliary zone using a low-dose protocol to obtain phases of the highest density gradient in the arteries and veins of the portal system, characterized in that the obtained CT images load into the Myrian program and produce anatomical image segmentation, in the first phase of contrast enhancement, the arterial bed is extracted, in the second phase - the portal system, a 3D area of interest is created and the automatic protocol “hepatic artery” is used to highlight the arteries of the celiac arteries pool, as well as the automatic protocol for highlighting veins “portal vein, solid filter”, pancreas formation is isolated in the phase of the greatest gradient with surrounding healthy tissues, then the tumor is isolated using the method of three-dimensional interpolation from the contour By the formation of education at several levels depending on the size and shape, the obtained areas of interest: arteries, veins, and tumor are displayed on a single three-dimensional rendering screen called “surface area of interest” by transporting the missing object from another phase of contrast enhancement, the resulting virtual model is evaluated on the presence of errors in the image by comparison with axial CT slices, then the resulting three-dimensional model is saved in a segmentation format and loaded into the Materialize program to create a three-dimensional print file, the STL file, the resulting file is downloaded to the FlashPrint 3D printing program and sent to the FlashForge Dreamer 3D printer, on the resulting three-dimensional model, supporting structures that were automatically created in FlashPrint are removed.

Images